morphine and Disease-Models--Animal

The article reviews advances in gastrointestinal aspects of cystic fibrosis (CF) published in the literature over the past year, and highlights new and interesting research.. Animal models can be used to understand the pathophysiology of gastrointestinal complications in CF. The CF mouse is useful for studying distal intestinal obstruction, dysmotility and dysbiosis, and the CF pig model has helped us better understand meconium ileus and pancreatic and hepatobiliary secretory problems. Studies in humans help elucidate the evolution of pancreatic insufficiency, how reflux may lead to lung disease, problems with intestinal dysmotility, mechanisms leading to pancreatitis and the increased prevalence of gastrointestinal cancer. Biomarkers are shedding light on CF-related liver disease. Rectal biopsies can help in diagnosis and in studying new drugs for CF.. Gastrointestinal complications of CF are likely to be seen with increasing frequency as patients with CF lead longer lives. CF animal models and modern research techniques are providing new insights into extrapulmonary complications. CF clinicians should be familiar with diagnosis and management of common gastrointestinal complications and should build bridges with specialists so that referrals can be made when needed.

Topics: Animals; Cystic Fibrosis; Digestive System Diseases; Disease Models, Animal; Dysbiosis; Gastrointestinal Diseases; Humans; Ileus; Intestinal Obstruction; Liver Diseases; Meconium; Mice; Pancreatic Diseases; Prognosis; Rectum; Swine

To use sheep and rat models and demonstrate that stressors activate fetal glucocorticoid (GC) system, corticotrophin-releasing factor (CRF) system and cholinergic neurotransmitter system (ChNS) leading to propulsive colonic motility and in utero meconium passage. Immunohistochemical studies (IHS) were performed to localize GC-Receptors, CRF-receptors and key molecules of ChNS in sheep fetal distal colon. CRF expression in placenta and enteric endocrine cells in fetal rat system were examined and the effects of acute hypoxia on in utero meconium passage was tested. IHS confirmed localization and gestation dependent changes in GC-Rs, CRF-Rs and cholinergic markers in sheep fetal colon. Rat placenta and enteric endocrine cells express CRF and gastrointestinal tract express CRF-Rs. Hypoxia is a potent inducer of meconium passage in term fetal rats. Stress is a risk factor for in utero meconium passage and laboratory animal models can be used to develop pharmacotherapy to prevent stress-induced in utero meconium passage.

Topics: Adrenocorticotropic Hormone; Animals; Disease Models, Animal; Gastrointestinal Motility; Glucocorticoids; Humans; Hypoxia; Meconium; Rats; Risk Factors; Sheep; Stress, Physiological

We synthesized derivatives of a natural alkaloid, conolidine, and evaluated these derivatives in the acetic acid-induced writhing test and formalin test in ddY mice after oral administration. As a result, we identified (5S)-6-methyl-1,3,4,5,6,8-hexahydro-7H-2,5-methano[1,5]diazonino[7,8-b]indol-7-one sulfate salt, 15a (DS54360155), with a unique and original bicyclic skeleton, as an analgesic more potent than conolidine. Moreover, 15a did not exhibit mu-opioid receptor agonist activity.

Topics: Analgesics; Animals; Disease Models, Animal; Humans; Mice; Receptors, Opioid, mu

Meconium aspiration syndrome (MAS) is a serious condition, which can be treated with exogenous surfactant and mechanical ventilation. However, meconium-induced inflammation, lung edema and oxidative damage may inactivate delivered surfactant and thereby reduce effectiveness of the therapy. As we presumed that addition of anti-inflammatory agent into the surfactant may alleviate inflammation and enhance efficiency of the therapy, this study was performed to evaluate effects of surfactant therapy enriched with budesonide versus surfactant-only therapy on markers of oxidative stress in experimental model of MAS. Meconium suspension (25 mg/ml, 4 ml/kg) was instilled into the trachea of young rabbits, whereas one group of animals received saline instead of meconium (C group, n = 6). In meconium-instilled animals, respiratory failure developed within 30 min. Then, meconium-instilled animals were divided into 3 groups according to therapy (n = 6 each): with surfactant therapy (M + S group), with surfactant + budesonide therapy (M + S + B), and without therapy (M group). Surfactant therapy consisted of two bronchoalveolar lavages (BAL) with diluted surfactant (Curosurf, 5 mg phospholipids/ml, 10 ml/kg) followed by undiluted surfactant (100 mg phospholipids/kg), which was in M + S + B group enriched with budesonide (Pulmicort, 0.5 mg/ml). Animals were oxygen-ventilated for additional 5 hours. At the end of experiment, blood sample was taken for differential white blood cell (WBC) count. After euthanizing animals, left lung was saline-lavaged and cell differential in BAL was determined. Oxidative damage, i.e. oxidation of lipids (thiobarbituric acid reactive substance (TBARS) and conjugated dienes) and proteins (dityrosine and lysine-lipoperoxidation products) was estimated in lung homogenate and isolated mitochondria. Total antioxidant capacity was evaluated in lung homogenate and plasma. Meconium instillation increased transmigration of neutrophils and production of free radicals compared to controls (P < 0.05). Surfactant therapy, but particularly combined surfactant + budesonide therapy reduced markers of oxidative stress versus untreated animals (P < 0.05). In conclusion, budesonide added into surfactant enhanced effect of therapy on oxidative damage of the lung.

Topics: Animals; Anti-Inflammatory Agents; Antioxidants; Bronchoalveolar Lavage Fluid; Budesonide; Disease Models, Animal; Female; Free Radicals; Inflammation; Lung; Lung Injury; Male; Meconium; Meconium Aspiration Syndrome; Neutrophils; Oxidative Stress; Pulmonary Edema; Pulmonary Surfactants; Rabbits; Trachea

Nine new grayanoids (1-9), together with 11 known compounds, were isolated from the roots of Rhododendron molle. The structures of the new compounds (1-9) were determined on the basis of spectroscopic analysis, including HRESIMS, and 1D and 2D NMR data. Compounds 4, 6, 12, and 14-20 showed significant antinociceptive activities in an acetic acid-induced writhing test. In particular, 14 and 15 were found to be more potent than morphine for both acute and inflammatory pain models and 100-fold more potent than gabapentin in a diabetic neuropathic pain model.

Topics: Amines; Analgesics; Animals; Cyclohexanecarboxylic Acids; Disease Models, Animal; Diterpenes; Drugs, Chinese Herbal; Female; Gabapentin; gamma-Aminobutyric Acid; Male; Mice; Molecular Structure; Morphine; Nuclear Magnetic Resonance, Biomolecular; Pain; Plant Roots; Rhododendron

Intestinal damage has been shown to occur when intra-amniotic meconium concentration exceeds threshold level. However, the mechanism of the meconium-induced intestinal damage is still unclear. Intestinal ischemia can cause intestinal damage in gastroschisis. This study was aimed to determine the effects of intra-amniotic meconium on the contractility of superior mesenteric artery (SMA).. Eighteen-day-old fertilized chick embryos (Gallus Domesticus) were extirpated and intestines were harvested. The SMA specimens were prepared as 4 mm segments in the organ bath with Krebs-Henseleit buffer. The isometric contraction responses of the SMA specimens were evaluated with norepinephrine, different meconium concentrations, and clear amniotic fluid. Maximum isometric contractions responses (MICR) of the SMA specimens were recorded with an amplifier system on a computer.. In the norepinephrine group, MICR was found as 2.92 ± 0.57 mN. While MICR of the 1/100 meconium group (highest meconium concentration) was found as 1.56 ± 0.40 mN, MICR of the clear amniotic fluid group was 0.41 ± 0.07 mN. The MICR of the norepinephrine group was significantly increased compared with the 1/100 meconium and clear amniotic fluid groups. MICR of the 1/100 meconium group was also found to be significantly increased compared with clear amniotic fluid group. No statistically significant difference was found among the meconium subgroups.. Intra-amniotic meconium in fetuses with gastroschisis might cause ischemic intestinal damage by reducing the intestinal blood flow. Further studies are needed to show the outcomes of the vasoactive effect of meconium on the SMA blood flow.

Topics: Animals; Chick Embryo; Disease Models, Animal; Gastroschisis; Humans; In Vitro Techniques; Intestines; Ischemia; Isometric Contraction; Meconium; Mesenteric Artery, Superior; Norepinephrine; Vasoconstriction; Vasoconstrictor Agents

Anti-inflammatory drugs are increasingly used for treatment of neonatal meconium aspiration syndrome (MAS), but their adverse effects are poorly known. Therefore, the aim of this study was to evaluate the effects of the antioxidant N-acetylcysteine on cardiovascular parameters in an animal model of MAS. Oxygen-ventilated rabbits were intratracheally instilled 4 mL/kg of meconium suspension (25 mg/mL) or saline. Thirty minutes later, meconium-instilled animals were given N-acetylcysteine (10 mg/kg, i.v.) or the same volume of saline. Changes in cardiovascular parameters (blood pressure, heart rate, and heart rate variability) were recorded over a 5-min course of solution administration, over 5 min after its end, and then hourly for 5 h. Oxidation markers (thiobarbituric acid-reactive substances (TBARS) and total antioxidant status) and aldosterone, as a non-specific marker of cardiovascular injury, were determined in plasma. Meconium instillation did not evoke any significant cardiovascular changes, but induced oxidative stress and elevated plasma aldosterone. N-acetylcysteine significantly reduced the mentioned markers of injury. However, its administration was associated with short-term increases in blood pressure and in several parameters of heart rate variability. Considering these effects of N-acetylcysteine, its intravenous administration in newborns with MAS should be carefully monitored.

Topics: Acetylcysteine; Acute Lung Injury; Aldosterone; Animals; Anti-Inflammatory Agents; Antioxidants; Blood Pressure; Disease Models, Animal; Heart Rate; Humans; Infant, Newborn; Injections, Intravenous; Intubation, Intratracheal; Lung; Meconium; Meconium Aspiration Syndrome; Oxidative Stress; Rabbits; Respiration, Artificial; Thiobarbituric Acid Reactive Substances

Meconium aspiration in newborns causes lung inflammation and injury, which may lead to meconium aspiration syndrome (MAS). In this study, the effect of the antioxidant N-acetylcysteine on respiratory and inflammatory parameters were studied in a model of MAS. Oxygen-ventilated rabbits were intratracheally given 4 mL/kg of meconium (25 mg/mL) or saline. Thirty minutes later, meconium-instilled animals were administered N-acetylcysteine (10 mg/kg; i.v.), or were left without treatment. The animals were oxygen-ventilated for additional 5 h. Ventilatory pressures, oxygenation, right-to-left pulmonary shunts, and leukocyte count were measured. At the end of experiment, trachea and lung were excised. The left lung was saline-lavaged and a total and differential count of cells in bronchoalveolar lavage fluid (BAL) was determined. Right lung tissue strips were used for detection of lung edema (expressed as wet/dry weight ratio) and peroxidation (expressed by thiobarbituric acid-reactive substances, TBARS). In lung and tracheal strips, airway reactivity to acetylcholine was measured. In addition, TBARS and total antioxidant status were determined in the plasma. Meconium instillation induced polymorphonuclear-derived inflammation and oxidative stress. N-acetylcysteine improved oxygenation, reduced lung edema, decreased polymorphonuclears in BAL fluid, and diminished peroxidation and meconium-induced airway hyperreactivity compared with untreated animals. In conclusion, N-acetylcysteine effectively improved lung functions in an animal model of MAS.

Topics: Acetylcysteine; Acute Lung Injury; Animals; Anti-Inflammatory Agents; Antioxidants; Bronchoalveolar Lavage Fluid; Disease Models, Animal; Humans; Infant, Newborn; Injections, Intravenous; Intubation, Intratracheal; Leukocyte Count; Lipid Peroxidation; Lung; Meconium; Meconium Aspiration Syndrome; Oxidative Stress; Pulmonary Edema; Rabbits; Respiration, Artificial; Thiobarbituric Acid Reactive Substances; Trachea

Since inflammation and oxidative stress are fundamental in the pathophysiology of neonatal meconium aspiration syndrome (MAS), various anti-inflammatory drugs have been used in experimental and clinical studies on MAS. This pilot study evaluated therapeutic potential of N-acetylcysteine in modulation of meconium-induced inflammation and oxidative lung injury. Oxygen-ventilated adult rabbits were intratracheally given 4 ml/kg of meconium (25 mg/ml) or saline (Sal, n = 6). Thirty minutes later, meconium-instilled animals were treated with intravenous N-acetylcysteine (10 mg/kg, Mec + NAC, n=6) or were non-treated (Mec, n = 6). All animals were oxygen-ventilated for additional 5 hours. Total and differential blood leukocyte counts were determined at baseline, and at 1, 3 and 5 h of the treatment. After sacrificing animals, left lung was saline-lavaged and total and differential cell counts in the bronchoalveolar lavage fluid were determined. Right lung was used for biochemical analyses and for estimation of wet-dry weight ratio. In lung tissue homogenate, thiobarbituric acid-reactive substances (TBARS), dityrosine, lysine-lipid peroxidation (LPO) products, and total antioxidant status (TAS) were detected. In isolated lung mitochondria, TBARS, dityrosine, lysine-LPO products, thiol group content, conjugated dienes, and activity of cytochrome c oxidase were estimated. To evaluate systemic effects of meconium instillation and NAC treatment, TBARS and TAS were determined also in plasma. To evaluate participation of eosinophils in the meconium-induced inflammation, eosinophil cationic protein (ECP) was detected in plasma and lung homogenate. Meconium instillation increased oxidation markers and ECP in the lung and decreased TAS (all P<0.05). NAC treatment reduced ECP and oxidation markers (all P<0.05, except of dityrosine in homogenate and conjugated dienes in mitochondria) and prevented a decrease in TAS (P<0.01) in lung homogenate compared to Mec group. In plasma, NAC decreased TBARS (P<0.001) and ECP, and increased TAS (both P<0.05) compared to Mec group. Concluding, N-acetylcysteine diminished meconium-induced inflammation and oxidative lung injury.

Topics: Acetylcysteine; Age Factors; Animals; Antioxidants; Biomarkers; Disease Models, Animal; Humans; Infant, Newborn; Inflammation Mediators; Leukocytes; Lipid Peroxidation; Lung; Lung Injury; Meconium; Meconium Aspiration Syndrome; Mitochondria; Oxidative Stress; Pneumonia; Pulmonary Edema; Rabbits; Thiobarbituric Acid Reactive Substances; Time Factors

Pain is the most common reason a patient sees a physician. Nevertheless, the use of typical painkillers is not completely effective in controlling all pain syndromes; therefore further attempts have been made to develop improved analgesic drugs. The present study was undertaken to evaluate the antinociceptive properties of physalins B (1), D (2), F (3), and G (4) isolated from Physalis angulata in inflammatory and centrally mediated pain tests in mice. Systemic pretreatment with 1-4 produced dose-related antinociceptive effects on the writhing and formalin tests, traditional screening tools for the assessment of analgesic drugs. On the other hand, only 3 inhibited inflammatory parameters such as hyperalgesia, edema, and local production of TNF-α following induction with complete Freund's adjuvant. Treatment with 1, 3, and 4 produced an antinociceptive effect on the tail flick test, suggesting a centrally mediated antinociception. Reinforcing this idea, 2-4 enhanced the mice latency reaction time during the hot plate test. Mice treated with physalins did not demonstrate motor performance alterations. These results suggest that 1-4 present antinociceptive properties associated with central, but not anti-inflammatory, events and indicate a new pharmacological property of physalins.

Topics: Analgesics; Animals; Anti-Inflammatory Agents; Disease Models, Animal; Edema; Freund's Adjuvant; Hyperalgesia; Male; Mice; Molecular Structure; Pain; Pain Measurement; Physalis; Secosteroids; Tumor Necrosis Factor-alpha

The concept of "ligand bias" at G protein coupled receptors has been introduced to describe ligands which preferentially stimulate one intracellular signaling pathway over another. There is growing interest in developing biased G protein coupled receptor ligands to yield safer, better tolerated, and more efficacious drugs. The classical μ opioid morphine elicited increased efficacy and duration of analgesic response with reduced side effects in β-arrestin-2 knockout mice compared to wild-type mice, suggesting that G protein biased μ opioid receptor agonists would be more efficacious with reduced adverse events. Here we describe our efforts to identify a potent, selective, and G protein biased μ opioid receptor agonist, TRV130 ((R)-30). This novel molecule demonstrated an improved therapeutic index (analgesia vs adverse effects) in rodent models and characteristics appropriate for clinical development. It is currently being evaluated in human clinical trials for the treatment of acute severe pain.

Topics: Acute Pain; Analgesics; Animals; Disease Models, Animal; Drug Discovery; GTP-Binding Proteins; HEK293 Cells; Humans; Mice; Models, Chemical; Molecular Structure; Rats; Receptors, Opioid, mu; Severity of Illness Index; Spiro Compounds; Structure-Activity Relationship; Thiophenes

Cystic fibrosis (CF) pigs develop disease with features remarkably similar to those in people with CF, including exocrine pancreatic destruction, focal biliary cirrhosis, micro-gallbladder, vas deferens loss, airway disease, and meconium ileus. Whereas meconium ileus occurs in 15% of babies with CF, the penetrance is 100% in newborn CF pigs. We hypothesized that transgenic expression of porcine CF transmembrane conductance regulator (pCFTR) cDNA under control of the intestinal fatty acid-binding protein (iFABP) promoter would alleviate the meconium ileus. We produced 5 CFTR-/-;TgFABP>pCFTR lines. In 3 lines, intestinal expression of CFTR at least partially restored CFTR-mediated anion transport and improved the intestinal phenotype. In contrast, these pigs still had pancreatic destruction, liver disease, and reduced weight gain, and within weeks of birth, they developed sinus and lung disease, the severity of which varied over time. These data indicate that expressing CFTR in intestine without pancreatic or hepatic correction is sufficient to rescue meconium ileus. Comparing CFTR expression in different lines revealed that approximately 20% of wild-type CFTR mRNA largely prevented meconium ileus. This model may be of value for understanding CF pathophysiology and testing new preventions and therapies.

Topics: Animals; Animals, Genetically Modified; Animals, Newborn; Cystic Fibrosis; Cystic Fibrosis Transmembrane Conductance Regulator; Disease Models, Animal; Fatty Acid-Binding Proteins; Female; Gene Expression; Humans; Ileum; Ileus; Infant, Newborn; Lung; Male; Meconium; Pancreas; Phenotype; Promoter Regions, Genetic; Radiography; Rats; Sus scrofa; Trachea

Meconium aspiration syndrome (MAS) remains a frequent cause of morbidity and mortality in term newborns. Our objective was to compare two modes of high-frequency ventilation, high-frequency oscillation (HFOV), and high-frequency percussive ventilation (HFPV) with conventional mechanical ventilation (CMV) in a piglet model of MAS.. Fifteen newborn piglets were anesthetized, paralyzed, and intubated. Following the instillation of a 3 ml/kg solution of meconium diluted to 30%, the piglets were randomized to one of three groups: high-frequency oscillation (HFOV; Sensormedics®), HFPV (Percussionaire®), or CMV (Siemens®). Animals were ventilated for 6 hr to maintain arterial blood gases within a normal range, that is, pH 7.35-7.45, PaO(2) 10-16 kPa, PaCO(2) 4-6.6 kPa. Arterial blood gas measurements, dynCrs and dynRrs, ventilator settings, and vital signs (heart rate, arterial blood pressure, transcutaneous pulse oxygen saturation, and temperature) were collected at 30, 60, 90, 120, 180, 240, 300, and 360 min after meconium instillation. Oxygenation index (OI) ([(fraction of inspired oxygen)(mean airway pressure)(100)]/PaO(2) ), mean airway pressure, dynamic lung function, secretions cleared and histological alterations were studied in all groups.. Mean airway pressure and OI were significantly lower in the CV and HFPV groups compared to the HFOV group (P < 0.05). There was no significant difference between groups regarding lung function, amount of secretions and histological alterations.. In our model of MAS in piglets, whilst effective gas exchange with a lower mean airway pressure was possible with both CMV and HFPV compared with HFOV there was no apparent difference in lung histology or secretions.

Topics: Animals; Blood Gas Analysis; Disease Models, Animal; High-Frequency Ventilation; Humans; Infant, Newborn; Lung; Meconium; Meconium Aspiration Syndrome; Random Allocation; Respiratory Function Tests; Swine; Treatment Outcome; Vital Signs

Inflammation, oxidation, lung edema, and other factors participate in surfactant dysfunction in meconium aspiration syndrome (MAS). Therefore, we hypothesized that anti-inflammatory treatment may reverse surfactant dysfunction in the MAS model. Oxygen-ventilated rabbits were given meconium intratracheally (25 mg/ml, 4 ml/kg; Mec) or saline (Sal). Thirty minutes later, meconium-instilled animals were treated by glucocorticoids budesonide (0.25 mg/kg, i.t.) and dexamethasone (0.5 mg/kg, i.v.), or phosphodiesterase inhibitors aminophylline (2 mg/kg, i.v.) and olprinone (0.2 mg/kg, i.v.), or the antioxidant N-acetylcysteine (10 mg/kg, i.v.). Healthy, non-ventilated animals served as controls (Con). At the end of experiments, left lung was lavaged and a differential leukocyte count in sediment was estimated. The supernatant of lavage fluid was adjusted to a concentration of 0.5 mg phospholipids/ml. Surfactant quality was evaluated by capillary surfactometer and expressed by initial pressure and the time of capillary patency. The right lung was used to determine lung edema by wet/dry (W/D) weight ratio. Total antioxidant status (TAS) in blood plasma was evaluated. W/D ratio increased and capillary patency time shortened significantly, whereas the initial pressure increased and TAS decreased insignificantly in Sal vs. Con groups. Meconium instillation potentiated edema formation and neutrophil influx into the lungs, reduced capillary patency and TAS, and decreased the surfactant quality compared with both Sal and Con groups (p > 0.05). Each of the anti-inflammatory agents reduced lung edema and neutrophil influx into the lung and partly reversed surfactant dysfunction in the MAS model, with a superior effect observed after glucocorticoids and the antioxidant N-acetylcysteine.

Topics: Acetylcysteine; Acute Lung Injury; Aminophylline; Animals; Anti-Inflammatory Agents; Antioxidants; Bronchoalveolar Lavage Fluid; Budesonide; Dexamethasone; Disease Models, Animal; Humans; Imidazoles; Infant, Newborn; Leukocyte Count; Lung; Meconium; Meconium Aspiration Syndrome; Neutrophils; Oxidative Stress; Phosphodiesterase Inhibitors; Pulmonary Edema; Pulmonary Surfactants; Pyridones; Rabbits

As inflammation plays an important role in the pathogenesis of neonatal meconium aspiration syndrome (MAS), anti-inflammatory agents including inhibitors of phosphodiesterases (PDE) are increasingly used in the treatment. To evaluate side effects of PDE inhibitors, this study analyzed changes in blood pressure, heart rate (HR) and heart rate variability (HRV) during and after intravenous aminophylline in the animal model of MAS. Oxygen-ventilated rabbits were given meconium intratracheally (25 mg/ml, 4 ml/kg) or saline. Thirty minutes later, the animals were treated by intravenous aminophylline (Syntophyllin, 2 mg/kg) or saline (sham-treated controls). A second dose of the treatment was given 2 h later. During (5 min) and immediately after (5 min) the treatment, and during 5 h after the treatment, mean blood pressure in the femoral artery (MAP), HR and HRV were evaluated. In meconium-instilled animals, increases in MABP, HR, and HRV were observed already 5 min after aminophylline administration, while in saline-instilled animals aminophylline increased HR and caused inconsistant changes in HRV parameters compared to sham-treated animals. Within 5 h after the treatment administration, MAP, HR, and HRV parameters gradually returned to the initial values. Concluding, intravenous aminophylline may lead to acute cardiovascular changes. Thus, if aminophylline is used for treatment of MAS, its possible cardiovascular effects should be considered, particularly in patients with cardiovascular instability.

Topics: Aminophylline; Animals; Blood Pressure; Bronchodilator Agents; Cardiovascular System; Disease Models, Animal; Heart Rate; Humans; Infant, Newborn; Lung; Meconium; Meconium Aspiration Syndrome; Phosphodiesterase Inhibitors; Rabbits

Since inflammation and oxidation play a key role in the pathophysiology of neonatal meconium aspiration syndrome, various anti-inflammatory drugs have been tested in the treatment. This study evaluated whether the phosphodiesterase (PDE) 3 inhibitor olprinone can alleviate meconium-induced inflammation and oxidative lung injury. Oxygen-ventilated rabbits intratracheally received 4 ml/kg of meconium (25 mg/ml) or saline. Thirty minutes after meconium/saline instillation, meconium-instilled animals were treated by intravenous olprinone (0.2 mg/kg) or were left without treatment. All animals were oxygen-ventilated for an additional 5 h. A bronchoalveolar lavage (BAL) of the left lungs was performed and differential leukocyte count in the sediment was estimated. The right lungs were used to determine lung edema by wet/dry weight ratio, as well as to detect oxidative damage to the lungs. In the lung tissue homogenate, total antioxidant status (TAS) was determined. In isolated lung mitochondria, the thiol group content, conjugated dienes, thiobarbituric acid-reactive substances (TBARS), dityrosine, lysine-lipid peroxidation products, and activity of cytochrome c oxidase (COX) were estimated. To evaluate the effects of meconium instillation and olprinone treatment on the systemic level, TBARS and TAS were determined in the blood plasma, as well. Meconium instillation increased the relative numbers of neutrophils and eosinophils in the BAL fluid, increased edema formation and concentrations of oxidation markers, and decreased TAS. Treatment with olprinone reduced the numbers of polymorphonuclears in the BAL fluid, decreased the formation of most oxidation markers in the lungs, reduced lung edema and prevented a decrease in TAS in the lung homogenate compared to non-treated animals. In the blood plasma, olprinone decreased TBARS and increased TAS compared to the non-treated group. Conclusion, the selective PDE3 inhibitor olprinone has shown potent antioxidative and anti-inflammatory effects in the meconium-induced oxidative lung injury.

Topics: Animals; Anti-Inflammatory Agents; Antioxidants; Bronchoalveolar Lavage Fluid; Disease Models, Animal; Edema; Humans; Imidazoles; Infant, Newborn; Inflammation; Leukocyte Count; Lung Injury; Meconium; Mitochondria; Oxidative Stress; Phosphodiesterase 3 Inhibitors; Pyridones; Rabbits

To examine the effects of pentoxifylline (PTX) on regional pulmonary and systemic inflammation after meconium aspiration, we studied 26 anesthetized and ventilated adult rats for 3 hours. Seventeen rats were instilled with human meconium (1.5 mL/kg, 65 mg/mL) intratracheally. After instillation of meconium, PTX (20 mg/kg, i.a.; n = 9) or saline (n = 8) was given to the subjects. Nine rats that were ventilated and not instilled with meconium served as sham group. Meconium instillation resulted in increased bronchoalveolar lavage (BAL) fluid tumor necrosis factor-α (TNF-α; P = 0.004 and P = 0.002, respectively), protein (P = 0.005 and P = 0.001, respectively) levels, and arterial oxygenation index (OI) in PTX and saline groups. PTX treatment prevented the increase of BAL fluid TNF-α, protein concentrations, and OI in the meconium-instilled lungs but had no statistically significant effect. These results indicate that meconium aspiration induces severe inflammation in the lung. PTX treatment affects the TNF-α production in the lungs and it may attenuate meconium-induced derangements.

Topics: Animals; Arteries; Bronchoalveolar Lavage Fluid; Disease Models, Animal; Humans; Infant, Newborn; Lung; Meconium; Meconium Aspiration Syndrome; Pentoxifylline; Pneumonia; Rats; Rats, Wistar; Tumor Necrosis Factor-alpha

Contact with amniotic fluid causes intestinal damage (ID) in fetuses with gastroschisis. Intraamniotic meconium has been shown to be responsible for ID, and ID has been shown to correlate with intraamniotic meconium concentrations. ID can be prevented by lowering the intraamniotic meconium concentration. A new method to lower intraamniotic meconium concentration might consist in the induction of fetal diuresis with intraamniotic diuretic injection. This hypothesis was tested in a rat model.. There were 4 experimental groups.. Rat fetuses without any manipulation. Fetuses were harvested by cesarean section for examination at E21.5 (Term). SHAM GROUP: On E18.5, the hind limb of the rat fetuses were exteriorized by hysterotomy and replaced in the uterus. GASTROSCHISIS GROUP: Gastroschisis was surgically created in rat fetuses on E18.5, under a dissection microscope (16×). GASTROSCHISIS+FUROSEMIDE GROUP: After surgical creation of gastroschisis on E18.5, intraamniotic furosemide (5 mg/kg) was administered to the fetuses on E20. All fetuses were harvested on E21.5.. There was no significant difference between intestinal serosal thicknesses of the control and sham groups. The serosal thickness was significantly higher in the gastroschisis group compared to the control group. In the gastroschisis+furosemide group, the intestinal serosal thickness was found significantly decreased compared with the gastroschisis group.. Intraamniotic furosemide injection caused a substantial decrease in ID encountered in gastroschisis. The induction of fetal diuresis with intraamniotic furosemide injection seems promising as a prenatal treatment modality.

Topics: Amnion; Animals; Disease Models, Animal; Diuresis; Diuretics; Fetal Therapies; Furosemide; Gastroschisis; Injections; Intestinal Diseases; Meconium; Rats; Rats, Sprague-Dawley

To discover analgesics for treating chronic pain 17 novel Schiff's bases, N,N'-(Z-allylidene-1,3-diyl)bisamino acid methyl esters were prepared from 1,1,3,3,-tetramethoxypropane and amino acid methyl esters. On tail-flick mouse model 20 micromol/kg of these Schiff's bases were orally administered, the analgesic action started 30 min after administration, reached the maximum 120 min after administration, and at 180 min this action was still observed. On a xylene-induced ear edema mouse model 20 micromol/kg of these Schiff's bases exhibited desirable anti-inflammation. Thus the present Schiff's bases are able to treat chronic pain from inflammation. The effect of the side chains of the amino acid residues of these Schiff's bases on the analgesic activity was explained with 3D QSAR.

Topics: Administration, Oral; Animals; Anti-Inflammatory Agents; Chronic Disease; Disease Models, Animal; Ear; Edema; Esters; Male; Mice; Mice, Inbred ICR; Models, Molecular; Molecular Structure; Pain; Quantitative Structure-Activity Relationship; Schiff Bases; Stereoisomerism; Xylenes

Lung disease causes most of the morbidity and mortality in cystic fibrosis (CF). Understanding the pathogenesis of this disease has been hindered, however, by the lack of an animal model with characteristic features of CF. To overcome this problem, we recently generated pigs with mutated CFTR genes. We now report that, within months of birth, CF pigs spontaneously developed hallmark features of CF lung disease, including airway inflammation, remodeling, mucus accumulation, and infection. Their lungs contained multiple bacterial species, suggesting that the lungs of CF pigs have a host defense defect against a wide spectrum of bacteria. In humans, the temporal and causal relations between inflammation and infection have remained uncertain. To investigate these processes, we studied newborn pigs. Their lungs showed no inflammation but were less often sterile than controls. Moreover, after introduction of bacteria into their lungs, pigs with CF failed to eradicate bacteria as effectively as wild-type pigs. These results suggest that impaired bacterial elimination is the pathogenic event that initiates a cascade of inflammation and pathology in CF lungs. Our finding that pigs with CF have a host defense defect against bacteria within hours of birth provides an opportunity to further investigate CF pathogenesis and to test therapeutic and preventive strategies that could be deployed before secondary consequences develop.

Topics: Animals; Animals, Newborn; Cystic Fibrosis; Disease Models, Animal; Ileus; Inflammation; Lung; Meconium; Mucus; Pancreatic Diseases; Radiography, Thoracic; Survival Analysis; Swine; Time Factors

To evaluate the impact of suction technique on the rate of meconium removal, oxygenation, and hemodynamics in an animal experimental model of meconium aspiration syndrome (MAS).. MAS was induced in ventilated rabbits using 3.5 ml/kg of 20% human meconium. Tracheal suction with either catheter suction (CS) or meconium aspirator (MA) was performed after meconium instillation. Percentage of meconium collection rate, PaO(2) trends for 2h after tracheal suction, and acute-phase SpO(2) trends were compared between CS and the other three groups, the tube was withdrawn while meconium was aspirated with an MA, then the trachea was reintubated 5, 10 or 15s after suctioning of meconium.. Percentage of meconium collection rate and PaO(2) showed no significant differences between groups. The MA group taking 15s for reintubation after meconium suctioning, showed a significantly lower acute-phase SpO(2) than the CS group (P<0.05). The time for SpO(2) to return to >or=90% was also longer in the MA group taking 15s for reintubation than in the CS group (P<0.05).. Intratracheal CS removed the same volume of meconium with less impact on desaturation compared with meconium aspiration in an animal model of MAS. Intratracheal CS may be benefit to remove meconium in non-vigorous infants with meconium-stained amniotic fluid at birth.

Topics: Animals; Blood Pressure; Catheterization; Catheters; Disease Models, Animal; Heart Rate; Humans; Infant, Newborn; Intubation, Intratracheal; Meconium; Meconium Aspiration Syndrome; Rabbits; Respiratory Function Tests; Respiratory Therapy; Suction; Trachea

We have investigated a series of phenolic diaryl amino piperidine delta opioid receptor agonists, establishing the importance of the phenol functional group and substitution on the piperdine nitrogen for delta agonist activity and selectivity versus the mu and kappa opioid receptors. This study uncovered compounds with improved agonist potency and selectivity compared to the standard, non-peptidic delta agonist SNC-80. In vivo anti-nociceptive activity of analog 8e in two rodent models is discussed, demonstrating the potential of delta agonists to provide a novel mechanism for pain relief.

Topics: Analgesics; Animals; Benzamides; Diphenylamine; Disease Models, Animal; Mice; Piperidines; Rats; Receptors, Opioid, delta; Structure-Activity Relationship

Cystic Fibrosis (CF) is a common autosomal recessive disease that affects multiple organs. The lack of an animal model with manifestations like those typically found in humans has slowed understanding of its pathogenesis. Therefore, because of the similarities between human and swine anatomy, biochemistry, physiology, size, and genetics, we chose to develop a porcine model of CF. We used homologous recombination in primary cultures of porcine fibroblasts to disrupt the CFTR gene and then used those cells as nuclear donors for somatic cell nuclear transfer. After crossing heterozygous pigs, we produced CFTR-/- pigs. The newborn CFTR null piglets manifested meconium ileus, pancreatic destruction, early focal biliary cirrhosis, and gall bladder abnormalities that were very similar to those observed in humans with CF. At birth, there were no abnormalities in the airway epithelium or submucosal glands and no evidence of inflammation, consistent with findings in the newborn human. We hope that this porcine model will help elucidate the pathogenesis of CF and thereby lead to the development of new mechanism-based therapies.

Topics: Animals; Animals, Genetically Modified; Animals, Newborn; Cystic Fibrosis; Cystic Fibrosis Transmembrane Conductance Regulator; Disease Models, Animal; Gallbladder Diseases; Gene Targeting; Humans; Ileus; Infant, Newborn; Liver Diseases; Meconium; Models, Biological; Mutation; Pancreatic Diseases; Phenotype; Respiratory System; Species Specificity; Swine

Fifteen different derivatives of an alpha- and beta-amyrin mixture were synthesized by acylation with appropriate anhydride or acid chlorides and oxidation in the presence of tert-butyl chromate or PCC. The molecular structures of the obtained compounds were confirmed by means of IR and (1)H NMR spectra. The compounds were screened for antinociceptive activity using the acetic acid pain model. The 3-O-acyl derivatives alpha- and beta-amyrin propionate 4, alpha- and beta-amyrin hexanoate 6, and alpha- and beta-amyrin octanoate 7 were found to be the most active compounds of the series. In addition, we also have found that alpha- and beta-amyrin octanoate 7 was able to reduce acetic acid-induced abdominal constriction when administered by oral route. Furthermore, this compound reduced the nociceptive response induced by intraplantar injection of formalin.

Topics: Analgesics; Animals; Disease Models, Animal; Mice; Molecular Structure; Oleanolic Acid; Pain; Structure-Activity Relationship; Triterpenes

Overdistension of the lungs is a cause of ventilator-induced lung injury. In meconium aspiration syndrome, irregular overdistension of the lungs often occurs.. We investigated whether surfactant replacement could restore the terminal airspaces in the lungs that had been distended after meconium aspiration.. Meconium aspiration was induced by injecting meconium (50 mg x kg(-1)) into the airways of adult rats anesthetized with pentobarbital and ventilated with pressure-preset mode. The animals were further ventilated with or without surfactant replacement (100 mg x kg(-1)), and the sizes of the terminal airspaces were determined after fixing the lungs at an airway pressure of 10 cm H2O on deflation.. Approximately 75 min after aspiration (early analysis point), alveolar ducts were widened and the mean ratio of the largest terminal airspace size class (> or =63,000 microm(2)) was 38.7% (n = 7), which was significantly higher than that of controls (6%, n = 7). Three hours after the early analysis point, the ratio increased to 50.2% (n = 7, p < 0.05), but surfactant replacement reversed the ratio to 18.8% (n = 7, p < 0.05).. In rats with meconium aspiration, surfactant replacement restored the distended terminal airspaces of the lungs and kept the spaces from irregular overdistension.

Topics: Animals; Disease Models, Animal; Humans; Infant, Newborn; Lung; Male; Meconium; Meconium Aspiration Syndrome; Pulmonary Surfactants; Rats; Rats, Wistar; Tidal Volume

Specific fatty acid ethyl esters (FAEE) in meconium of newborns have been shown to correlate with maternal ethanol exposure. An animal model is needed to assess the validity of this biomarker. We hypothesized that the pregnant/fetal sheep is a feasible animal model for validating FAEE as a biomarker of prenatal ethanol exposure. Nine pregnant ewes were treated during the third trimester with different i.v. ethanol doses. The control group consisted of 14 pregnant ewes exposed to similar volumes of saline. On gestational d 133, the fetuses were delivered and meconium samples removed. FAEEs were quantified by gas chromatography-flame ionization detection. FAEEs were found in both control and ethanol exposed fetuses. Ethyl oleate, ethyl linoleate, and ethyl arachidonate levels were significantly higher in the ethanol-exposed sheep. Ethyl oleate was the FAEE that correlated most strongly with alcohol ingestion during pregnancy and had the greatest area under the curve (0.94). Using a cut-off value of 131 ng/g ethyl oleate dry weight, sensitivity was 89% and specificity was 100%. In conclusion, pregnant ewes are a feasible model for validating biomarkers of prenatal ethanol exposure. Ethyl oleate, ethyl linoleate, and ethyl arachidonate may be useful biomarkers of prenatal alcohol exposure.

Topics: Animals; Area Under Curve; Disease Models, Animal; Esters; Ethanol; Fatty Acids; Female; Fetal Alcohol Spectrum Disorders; Maternal Exposure; Meconium; Oleic Acids; Pregnancy; Pregnancy, Animal; Sheep; Sheep, Domestic

The pulmonary renin-angiotensin system (RAS) contributes to inflammation and epithelial apoptosis in meconium aspiration. It is unclear if both angiotensin II receptors (ATR) contribute, where they are expressed and if meconium modifies subtype expression. We examined ATR subtypes in 2 wk rabbit pup lungs before and after meconium exposure and with and without captopril pretreatment or type 1 receptor (AT1R) inhibition with losartan, determining expression and cellular localization with immunoblots, RT-PCR and immunohistochemistry, respectively. Responses of cultured rat alveolar type II pneumocytes were also examined. Type 2 ATR were undetected in newborn lung before and after meconium instillation. AT1R were expressed in pulmonary vascular and bronchial smooth muscle and alveolar and bronchial epithelium. Meconium increased total lung AT1R protein approximately 3-fold (p = 0.006), mRNA 29% (p = 0.006) and immunostaining in bronchial and alveolar epithelium and smooth muscle, which were unaffected by captopril and losartan. Meconium also increased AT1R expression >3-fold in cultured type II pneumocytes and caused concentration-dependent cell death inhibited by losartan. Meconium increases AT1R expression in newborn rabbit lung and cultured type II pneumocytes and induces AT1R-mediated cell death. The pulmonary RAS contributes to the pathogenesis of meconium aspiration through increased receptor expression.

Topics: Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Animals; Apoptosis; Captopril; Cell Death; Cells, Cultured; Disease Models, Animal; Humans; Immunohistochemistry; Infant, Newborn; Losartan; Male; Meconium; Meconium Aspiration Syndrome; Pulmonary Alveoli; Rabbits; Rats; Rats, Sprague-Dawley; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Renin-Angiotensin System; RNA, Messenger; Up-Regulation

Chiral tetrahydroquinoline derivatives have been prepared by an asymmetric Mannich-type condensation reaction using commercially available vinyloxyethylsilane and a N-arylimino R-(+)-t-butyl lactate ester, in the presence of a catalytic amount of metal triflates as Lewis acids. This synthetic approach gave rise to the target aldehyde intermediate in moderate facial diastereoselectivity and in high chemical yield. This efficient route enabled to scale up the synthesis of an orally bioavailable glycine antagonist showing outstanding in vivo anti-hyperalgesic activity in different animal models of sustained inflammation and chronic neuropathic pain.

Topics: Animals; Biological Availability; Disease Models, Animal; Glycine; Hydroquinones; Hyperalgesia; Inflammation; Pain; Rats; Stereoisomerism; Structure-Activity Relationship

Sickle cell anemia is a common genetic disorder in African Americans. Opioid analgesics are traditionally the treatment for the severe pain associated with this disease. Here we reveal that the opioid antagonist naloxone possesses potent analgesic activity in two transgenic mouse models of sickle cell anemia (NY1DD and hBERK1) and not in their respective controls (ICR-CD1 and C57BL/6J) when administered by three parenteral routes [intracerebroventricular (i.c.v.), intrathecal, and subcutaneous]. In the NY1DD mice, naloxone (i.c.v.) possessed approximately 300-fold greater potency than morphine (i.c.v.). Other opioid antagonists (naltrexone, norbinaltorphimine, and naltrindole) were substantially less effective in producing analgesia. Naloxone and morphine were synergistic in NY1DD mice, suggesting different receptor systems. Microarray analysis suggested naloxone-induced down-regulation of the CC chemokine receptor (CCR)5 in NY1DD mice but not in control mice. Pretreatment of control mice with CC chemokine ligand 5 [CCL5 (RANTES)] enabled naloxone to produce analgesia similar to that observed in NY1DD mice. Mu opioid receptor knockout mice treated similarly also displayed analgesia. That the effect of CCL5 was specifically related to CCR5 and/or CCR1 activation was demonstrated by antagonism of analgesia with the chemokine antagonist methionylated RANTES. Similar antagonism of naloxone-induced analgesia also was observed when NY1DD mice were pretreated with methionylated RANTES. These results indicate that CCR5/CCR1 receptors are directly or indirectly involved in analgesia produced by naloxone. The present study suggests that naloxone may be clinically useful in the treatment of pain associated with sickle cell disease and other disorders involving inflammation.

Topics: Analgesics; Analgesics, Opioid; Anemia, Sickle Cell; Animals; Chemokine CCL5; Disease Models, Animal; Dose-Response Relationship, Drug; Down-Regulation; Drug Synergism; Injections, Intraventricular; Injections, Spinal; Injections, Subcutaneous; Male; Mice; Mice, Inbred C57BL; Mice, Inbred ICR; Mice, Knockout; Mice, Transgenic; Morphine; Naloxone; Pain; Pain Measurement; Receptors, CCR5

In humans, fetal in utero meconium (MEC) passage rarely occurs before term gestation. We hypothesized the existence of inhibitory mechanism(s) preventing colonic motility and MEC passage prior to term.. Longitudinal smooth muscle strips prepared from distal colon of preterm ovine fetuses (130-132 d; term = 148-152 d) were examined for their contractile responses to muscarinic receptor agonist (bethanechol) and both nonspecific (atropine) and receptor subtype specific antagonists (M1: pirenzepine dihydrochloride, M2 methoctramine, M3: 4-diphenylacetoxy-N-methlpiperidine methiodide [4-DAMP] and M4: tropicamide) in an in vitro organ bath system. Effects of corticotrophin releasing factor (CRF) and Urocortin I (URO-I), known modulators of colonic motility and smooth muscle contractility, were studied on bethanechol-induced contractility. Immunohistochemical analysis was performed to confirm the expression of CRF and URO-I, and muscarinic and CRF R2 receptors in distal colon.. Bethanechol induced smooth muscle contractions via muscarinic receptor subtype M3. CRF and URO-I elicited a significant inhibition of bethanechol induced contraction. Immunohistochemical analysis verified the expression of muscarinic receptor subtype M3, CRF, URO-I and CRF-receptor-R2 in distal colon.. Inhibition of M3 dependent distal colonic motility by CRF system may prevent the passage of MEC in the preterm ovine fetus.

Topics: Animals; Bethanechol; Colon; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Fetus; Gastrointestinal Motility; Immunohistochemistry; Meconium; Muscarinic Agonists; Muscle Contraction; Muscle, Smooth; Pirenzepine; Pregnancy; Pregnancy, Animal; Probability; Receptors, Corticotropin-Releasing Hormone; Sensitivity and Specificity; Sheep, Domestic; Tissue Culture Techniques

Several studies of vasoactive intestinal polypeptide (VIP) demonstrated its potent vasodilative effects on pulmonary and systemic circulation. However, no hemodynamic studies were performed to depict the effects of VIP in an in vivo model of pulmonary arterial hypertension (PAH), thereby limiting a complete understanding of the overall hemodynamic effects of VIP in PAH.. The pulmonary and systemic hemodynamic effects of intravenous infusion of 100 ng/kg per minute of VIP in control and pulmonary hypertensive piglets at 6 to 8 weeks of age were assessed. Pulmonary arterial hypertension was induced after the instillation of meconium solution in the subjects' trachea and was characterized by the establishment of a persistently elevated pulmonary arterial pressure, diminished cardiac output, and elevated pulmonary-to-systemic vascular resistance (PVR/SVR) ratio.. Continuous intravenous infusion of VIP markedly decreased PVR/SVR ratio in pulmonary hypertensive subjects; however, it lowered blood pressure without causing any significant changes in PVR/SVR ratio in control subjects. Collectively, these results suggest an overall pulmonary vasodilative effect of VIP in PAH.

Topics: Analysis of Variance; Animals; Cardiac Output; Disease Models, Animal; Heart Rate; Humans; Hypertension, Pulmonary; Infant, Newborn; Infusions, Intravenous; Meconium; Random Allocation; Swine; Vascular Resistance; Vasoactive Intestinal Peptide

Complications from meconium aspiration syndrome (MAS) remain significant despite a variety of therapeutic interventions. Clara cell protein (CC10) is a novel anti-inflammatory agent that can also inhibit phospholipase A2 (PLA2) (an important component of meconium). The present study examined whether administration of recombinant human CC10 (rhCC10) would reduce inflammation and improve lung function in a piglet model of MAS. Following meconium instillation, piglets exhibited significant physiologic dysfunction that improved significantly after surfactant administration. Analysis of tracheal aspirates revealed significant increases in both tumor necrosis factor (TNF) alpha and interleukin (IL)-8 after meconium instillation. rhCC10-treated animals had significantly lower TNF-alpha levels at 24 h (561 +/- 321 versus 1357 +/- 675 pg/mL, p < 0.05) compared with saline controls. There were no differences between rhCC10-treated and untreated groups with respect to other measured physiologic variables or inflammatory markers, including secretory PLA2 activity. Histologic analyses revealed marked inflammatory infiltrates and thickened alveolar walls, but no significant differences among rhCC10 and control animals. Newborn piglets with MAS have significant physiologic dysfunction, marked inflammatory changes and histologic abnormalities, which was partially counteracted by a single dose of exogenous surfactant and rhCC10.

Topics: Animals; Animals, Newborn; Anti-Inflammatory Agents; Bronchoalveolar Lavage Fluid; Disease Models, Animal; Drug Therapy, Combination; Enzyme Inhibitors; Humans; Infant, Newborn; Interleukin-8; Lung; Meconium; Meconium Aspiration Syndrome; Phospholipases A2, Secretory; Pulmonary Surfactants; Recombinant Proteins; Swine; Time Factors; Tumor Necrosis Factor-alpha; Uteroglobin

The effects of dexamethasone on in vitro airway reactivity associated with lung inflammation were investigated in rabbits with meconium aspiration. Oxygen-ventilated adult rabbits received an intratracheal bolus of 4 ml/kg body weight of saline (Sal, n = 4) or human meconium (25 mg/ml). Thirty minutes later, meconium-instilled animals intravenously received 0.5 mg/kg of dexamethasone (Dexa, n = 6), or were left without treatment (Meco, n = 5). The animals were ventilated for a further 5 hr and then sacrificed. The left lungs were lavaged with saline, and the white blood cell (WBC) count was estimated. Tracheal and right-lung tissue strips were placed into organ chambers with Krebs-Henseleit solution. Cumulative doses of histamine (10(-8)-10(-3) mol/l) and acetylcholine (10(-8)-10(-3) mol/l) were added to the chambers, and recordings of contractions were made after a 30-min loading phase with a tension of 4 grams, and another 30-min adaptation phase with a tension of 2 g. Tracheal smooth muscle in vitro reactivity to histamine was higher in the Meco than in the Sal group, and dexamethasone decreased the reactivity compared to the Meco group (P < 0.05). Lung tissue in vitro reactivity to histamine was slightly higher in the Meco than in the Sal group (P > 0.05), and dexamethasone decreased the reactivity compared to both the Meco and Sal groups (P < 0.05). No between-group differences were observed in tracheal or lung in vitro reactivity to acetylcholine (P > 0.05). In the Meco group, blood WBC (P > 0.05) and neutrophil (P < 0.05) counts were lower than in the Sal and Dexa groups. Lung neutrophils and eosinophils were higher in both the Meco and Dexa groups than in the Sal group (P < 0.01). Dexamethasone decreased neutrophils (P < 0.05) compared to the Meco group. Meconium-induced airway hyperreactivity to histamine and lung inflammation were alleviated by dexamethasone.

Topics: Animals; Anti-Inflammatory Agents; Dexamethasone; Disease Models, Animal; Humans; In Vitro Techniques; Infant, Newborn; Lung; Meconium; Meconium Aspiration Syndrome; Muscle, Smooth; Pneumonia; Rabbits; Trachea; Treatment Outcome

Meconium aspiration syndrome (MAS) remains a relevant cause of neonatal respiratory failure and is characterized by severe impairment of pulmonary gas exchange, surfactant inactivation, and pronounced inflammatory changes. Surfactant administration has been shown as an effective treatment strategy in MAS. The present study aimed at investigating the impact of a recombinant surfactant protein (SP)-C-based surfactant on pulmonary gas exchange and lung function in this model of neonatal lung injury. Furthermore, SP-B and -C were determined on the transcriptional and protein level.. Laboratory experiment.. University laboratory.. Twenty three newborn piglets (median age 6 days, weight 1900-2500 g).. Piglets were intubated and mechanically ventilated and then received 20% sterile meconium (5 mL/kg) for induction of lung injury. After 30 mins, animals were randomized for control (n = 7, MAS controls), recombinant SP-C surfactant (n = 8), or natural surfactant (n = 8). Surfactant preparations were administered as an intratracheal bolus (75 mg/kg), and animals were ventilated for another 330 mins. Nonventilated newborn piglets at term (n = 28; median weight 1484 g, range 720-1990 g) served as a healthy reference group (healthy controls).. Lung function variables, arterial blood gas samples, and lung tissues were obtained. Expression of SP-B and -C messenger RNA was quantified in left lung lobe tissue using real-time polymerase chain reaction. Protein concentrations were determined by enzyme-linked immunosorbent assay. Scanning electron microscopy and transmission electron microscopy were performed in tissue samples of the right lung lobe. Compared with healthy controls, SP-B messenger RNA expression was significantly increased in MAS (p < .02), whereas SP-C messenger RNA expression was found to be significantly reduced (p < .001). SP concentrations, however, were not significantly different. Although a significant improvement of gas exchange and lung function was observed after surfactant administration in both groups, surfactant messenger RNA expression and protein concentrations were not significantly altered. Scanning and transmission electron microscopy showed severe pulmonary ultrastructural changes after meconium aspiration improving after surfactant treatment.. Impairment of lung function in MAS, associated with marked changes in SP messenger RNA expression, can be sufficiently treated using recombinant SP-C-based or natural surfactant. Despite improved lung function and gas exchange as well as pulmonary ultrastructure after treatment, pulmonary SP messenger RNA expression and concentrations remained significantly affected, giving important insight into the time course following surfactant treatment in MAS.

Topics: Animals; Animals, Newborn; Base Sequence; Blood Gas Analysis; Disease Models, Animal; Female; Humans; Infant, Newborn; Meconium; Meconium Aspiration Syndrome; Molecular Sequence Data; Pulmonary Gas Exchange; Pulmonary Surfactant-Associated Protein C; Pulmonary Surfactants; Random Allocation; Recombinant Proteins; Reference Values; Respiratory Function Tests; Respiratory Insufficiency; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sensitivity and Specificity; Swine

Topics: Animals; Animals, Newborn; Disease Models, Animal; Humans; Infant, Newborn; Meconium; Meconium Aspiration Syndrome; Pulmonary Surfactant-Associated Protein C; Pulmonary Surfactants; Random Allocation; Respiratory Function Tests; Respiratory Insufficiency; Sensitivity and Specificity; Swine

Topics: Amniotic Fluid; Animals; Disease Models, Animal; Gastroschisis; Inflammation; Intestinal Diseases; Meconium; Rats

Topics: Animals; Animals, Newborn; Disease Models, Animal; Meconium; Pneumonia, Aspiration; Swine

Hyaluronan (HA), an ionic polymer, is normally present in the alveolar subphase and is known to decrease lung surfactant inactivation caused by serum in vitro. In this study, we examined whether HA can ameliorate the inactivating effects of meconium in vitro and in vivo. Surface activities of various mixtures of Survanta, HA, and meconium were measured using a modified pulsating bubble surfactometer. With meconium, almost all surface activity measures were improved by the addition of HA of several molecular weights at a concentration of 0.25%. Anesthetized, paralyzed rats were maintained on positive-pressure ventilation. After lung injury by instillation of meconium, they were treated with Survanta, Survanta with HA, or control mixtures. Serial measures of blood gases and peak inspiratory pressure were recorded for the duration of the experiment. When the Survanta plus HA group was compared with the Survanta alone group, arterial oxygen tension averaged 117% higher, peak inspiratory pressure was 27% lower at the end of the experiment, and lung compliance also showed significant improvement. These results indicate that HA added to Survanta decreases inactivation caused by meconium in vitro and improves gas exchange and pulmonary mechanics of animals with meconium-induced acute lung injury.

Topics: Animals; Arteries; Biological Products; Disease Models, Animal; Humans; Hyaluronic Acid; In Vitro Techniques; Infant, Newborn; Ions; Lung; Lung Injury; Male; Meconium; Meconium Aspiration Syndrome; Oxygen; Phospholipids; Polymers; Rats; Rats, Sprague-Dawley; Surface-Active Agents; Time Factors

The purpose of this study was to examine the effects of prolonged in utero meconium exposure on adult learning and memory, as measured by the Morris water maze.. Timed pregnant Long-Evans rats were studied. On gestational day 20 (term, 21 days of gestation), laparotomy was performed, and each maternal animal received an injection of clear amniotic fluid or meconium-stained amniotic fluid into each gestational sac. The laparotomy incision was closed, and the animals received postoperative monitoring through delivery. On postnatal days 145 to 148, the offspring underwent Morris water maze testing. The mean (+/-SEM) for the latency time was reported for each day's trial and compared between groups.. There were significant differences between meconium-stained amniotic fluid group and clear amniotic fluid group in the mean time to platform on day 1 (82.7 +/- 1.8 seconds vs 75.9 +/- 3.0 seconds; P=.04), day 2 (60.5 +/- 3.5 seconds vs 47. 8 +/- 4.6 seconds; P=.03), and day 3 (56.5 +/- 4.5 seconds vs 34.7 +/- 4.4 seconds; P=.001). However, there were no differences on days 4 and 5. There were also no differences between recall and response learning trials that were done after a 12-day retention period.. In the absence of hypoxia or infection, prolonged in utero meconium exposure is associated with a delay of spatial learning in the adult rat.

Topics: Analysis of Variance; Animals; Animals, Newborn; Disease Models, Animal; Female; Maze Learning; Meconium; Memory Disorders; Motor Activity; Pregnancy; Pregnancy, Animal; Prenatal Exposure Delayed Effects; Probability; Rats; Rats, Long-Evans; Reference Values; Spatial Behavior; Time Factors

To evaluate effects of inhaled nitric oxide (iNO) on the expression of lung neutrophil adhesion molecule CD(11b) in experimental meconium aspiration pneumonia treated with conventional mechanical ventilation under room air or 100% O(2).. Rabbits were randomly allocated to 10 groups (n = 60), 6 of each group. Control or meconium aspiration pneumonia model groups were inhaled with room air or 100% O(2). Six treatment groups were treated with continuous NO inhalation at the doses of 6 x 10(-6), 10 x 10(-6) and 20 x 10(-6), respectively for 12 hours under room air or 100% O(2). The ratio of wet/dry (W/D) lung weight, alveolar septal width (ASW), myeloperoxidase (MPO) activity and lung injury score were measured. The expression of CD(11b) in neutrophils of the bronchoalveolar lavage fluid (BALF) was detected with flow cytometry.. After 12 hours ventilation, the oxygenation was maintained better in treatment groups under different O(2) concentrations than that in model groups. Inflammatory evidence was found in lungs from all the model groups and treatment groups, which was characterized by serious inflammatory cell infiltration in alveolar space and hyaline membrane formation. The lung inflammation was decreased in all groups with nitric oxide inhalation. The ratio of W/D lung weight and ASW among different groups had no significant difference. MPO activities were significantly decreased in groups treated with 10 x 10(-6) and 20 x 10(-6) iNO compared with the model groups [with the concentration of 21% O(2), (1.8 +/- 0.2) U/g vs (4.4 +/- 0.5) U/g and (2.0 +/- 0.1) U/g vs (4.4 +/- 0.5) U/g;with the concentration of 100% O(2), (1.7 +/- 0.4) U/g vs (2.8 +/- 0.5) U/g and (1.4 +/- 0.3) U/g vs (2.8 +/- 0.5) U/g, P < 0.05, respectively]. MPO activities in the 20 x 10(-6) iNO group under 100% O(2) were significantly reduced compared with those under 21%O(2) [(1.4 +/- 0.3) U/g vs (2.0 +/- 0.1) U/g, P < 0.05]. Nitric oxide inhalation with the doses of 10 x 10(-6) and 20 x 10(-6) significantly decreased the expression of CD(11b) (MFI) in neutrophils of the BALF compared with the expressions in model groups without NO treatment (with 21% O(2), 121 +/- 20 vs 392 +/- 204 and 112 +/- 30 vs 392 +/- 204; with 100% O(2), 113 +/- 24 vs 293 +/- 65 and 102 +/- 14 vs 293 +/- 65, P < 0.05, respectively). Under the same iNO dose (10 x 10(-6) or 20 x 10(-6)) no statistic difference was found between groups of different inspired oxygen concentrations (21% and 100%).. Inhaled nitric oxide with the doses of 10 x 10(-6) to 20 x 10(-6) could significantly down-regulate the CD(11b) expression in neutrophil of the BALF and reduce the neutrophil sequestration and MPO activity in rabbit lungs, which may decrease the lung inflammation process in meconium aspiration pneumonia.

Topics: Administration, Inhalation; Animals; CD11b Antigen; Disease Models, Animal; Female; Flow Cytometry; Lung; Male; Meconium; Neutrophils; Nitric Oxide; Peroxidase; Pneumonia, Aspiration; Rabbits; Random Allocation

To evaluate pulmonary histopathology for confirming amniotic fluid embolism.. The Capra hircus (goat) model with fresh, homologous amniotic fluid was used. Raw fluid (n = 8), fluid filtered through a 5-microns filter (n = 14) and meconium-stained fluid with 1-7% solid debris (n = 7) were injected. Three hours after embolization the animals were euthanized and specimens collected. Three to five areas of lung were sampled based on the most abnormal areas visually. Traditional and special stains were utilized. The study protocol was approved by the institutional review board and animal use and care committee. Statistical analysis was by chi 2 with Yates correction. Significance was defined as P < .05.. Amniotic fluid debris (fetal squames, mucin or foreign pigments) was found in 10 of 29 animals (34.5%). Debris was found in 7/7 (100%) of the meconium group, 2/8 (25%) of the raw fluid group and 1/14 of the filtered group (7%). The likelihood of finding debris in amniotic fluid embolism with meconium-stained fluid was greater than with raw (P < .017) or filtered amniotic fluid (P < .001).. In this animal model, histopathologic confirmation of amniotic fluid embolism was an unreliable marker of the event except in cases of amniotic fluid embolism involving meconium-stained fluid.

Topics: Animals; Diagnosis, Differential; Disease Models, Animal; Embolism, Amniotic Fluid; False Negative Reactions; Female; Goats; Lung; Meconium; Pregnancy; Sensitivity and Specificity

The rationale for in utero repair of myelomeningocele has been supported experimentally by the observation of preserved neural function after prenatal closure of surgically created defects compared with nonrepaired controls. The mechanism of injury to the exposed neural elements is unknown. Postulated mechanisms include trauma to the herniated neural elements or progressive injury from amniotic fluid exposure as gestation proceeds. A component of amniotic fluid that may contribute to neural injury is meconium. In the current study the effect of human meconium on the exposed spinal cord in a fetal rat model of myelomeningocele was examined.. Twenty time-dated pregnant rats underwent laparotomy at 181/2 days of gestation. The exposed uterus was bathed in ritrodrine for tocolysis. The amniotic cavity was opened over the dorsal midline of the fetal rat, and, under a dissecting microscope (x25), a 2- to 3-level laminectomy was performed. Under magnification (x40), the translucent dura was opened using a 25-gauge needle as a knife. Two fetuses per dam were operated on. In the control group, the amniotic fluid was restored with saline solution, whereas in the experimental group a solution of Human meconium diluted (10%) in saline was used to restore the amniotic fluid. Fetuses were harvested by cesarean section at 211/2 days' gestational age. The liveborn pups were then killed and fixed in 10% formaline. Sections 10 micrometer thick were stained with H&E and studied by light microscopy for evidence of spinal cord injury.. Seven of 20 (35%) experimental rat pups and 6 of 20 (30%) control rat pups were liveborn. All liveborn pups had severe paralysis of the hindlimbs and tail, so that functional differences between the 2 groups could not be detected. Histologic examination of 13 spinal cords at the site of surgical exposure showed that necrosis of neural tissue in 5 of 7 meconium-exposed rat pups was increased when compared with that observed in the 6 fetuses exposed to amniotic fluid without meconium. In general, inflammation was greater and repair processes appeared delayed in meconium-exposed rat pups.. Exposure of the spinal cord of fetal rats to amniotic fluid by surgically created myelomeningocele leads to severe functional impairment. Histologically recognizable necrosis of neural elements was increased in those animals that were exposed to diluted human meconium in the amniotic fluid. The results support the hypothesis that meconium may contribute to the pathophysiology of spinal cord injury observed in myelomeningocele.

Topics: Amniotic Fluid; Animals; Disease Models, Animal; Female; Humans; Infant, Newborn; Male; Meconium; Meningomyelocele; Necrosis; Pregnancy; Rats; Spinal Cord; Uterus

Topics: Animals; Disease Models, Animal; Gastroschisis; Humans; Meconium; Species Specificity

A hallmark of amniotic fluid embolism is the induction of coagulation defects. Little is known about the nature of these defects or the causative agent or agents. The purpose of this study was to assess the effects of meconium containing (native) meconium-amniotic-fluid infusion (MAFI) and meconium-free (centrifuged) amniotic-fluid infusion (AFI) on the coagulation system in the mini-pig model.. Laboratory study.. University institute animal laboratory.. Near-term pregnant Göttingen bred mini-pigs in three groups (control, MAFI, AFI) of six animals each.. After induction of anesthesia, amniotic fluid was collected by cesarean section in all animals. Depending on the group, animals received either Ringer's solution (control), native amniotic fluid (MAFI), or centrifuged amniotic fluid (AFI) via an ear vein.. Blood samples were taken from a central vein before infusion (baseline), immediately after infusion, every 10 mins until 90 mins after infusion, and finally, every 20 mins until 150 mins after infusion. The following parameters were measured: Platelets, partial thromboplastin time, prothrombin time, fibrinogen, factors V, VII, VIII, antithrombin III, and protein C. The values relative to baseline in the MAFI and AFI groups were compared with control by rank order test. A p<.05 was considered statistically significant. Compared with the control group, platelets were lower in the MAFI group (p<.005), PTT was prolonged in both the MAFI and AFI groups (p<.005), fibrinogen was lower in both the MAFI and AFI groups (p<.05), prothrombin index was lower (i.e., prothrombin time was prolonged) in the MAFI group (p<.05), and protein C was lower in the MAFI group (p<.005).. Both MAFI and, to a much lesser extent, AFI cause an activation of coagulation in mini-pigs. The changes induced by meconium-free AFI are probably not sufficient to explain the high mortality of the condition.

Topics: Amniotic Fluid; Animals; Blood Coagulation; Blood Coagulation Tests; Disease Models, Animal; Embolism, Amniotic Fluid; Female; Meconium; Pregnancy; Statistics, Nonparametric; Swine; Swine, Miniature; Time Factors

To compare the effects of the sustained exposure to inhaled nitric oxide (NO) on pulmonary gas exchange, cardiovascular function and lung mechanics in newborn lambs with pulmonary hypertension induced by tracheal instillation of meconium. Fifteen newborn lambs (<6 d old) were studied in three groups (n = 5): control, and pulmonary hypertension (5 mL x kg[-1] of a 20% meconium solution) with or without inhaled NO (20 ppm) exposure. Heart rate, systemic and pulmonary arterial pressures, arterial pH and blood gases, cardiac output, and pulmonary mechanics were measured. The exposure to inhaled NO in lambs with pulmonary hypertension, induced by experimental meconium aspiration, produced a transient response. There were a transient improvement in gas exchange, a decrease in pulmonary arterial pressure and airway resistance, without changes in cardiovascular profile. The transient and incomplete response to inhaled NO in experimental MAS might be related to the fact that hypoxemia is not only due to pulmonary vasoconstriction but also to parenchymal lung disease. We hypothesize that this poor and transient response could probably be avoided if strategies that increase lung recruitment, were applied before inhaled NO exposure.

Topics: Administration, Inhalation; Animals; Animals, Newborn; Disease Models, Animal; Heart Rate; Meconium; Nitric Oxide; Pulmonary Circulation; Pulmonary Gas Exchange; Respiratory Mechanics; Sheep; Vascular Resistance

Impaired pulmonary mechanics can cause chest wall distortion (CWD) so that work of breathing is dissipated in deforming the rib cage. We hypothesized that respiratory mechanical unloading as a technique of assisted mechanical ventilation would reduce CWD in animals with injured lungs. We studied five piglets and five adult rabbits to test across different ages and chest configurations. As a result of intratracheal meconium instillation, lung compliance decreased from 21 (median; range 17-35) to 9.5 (6.7-14) mL/kPa/kg in rabbits and from 26 (18-31) to 7.9 (4.9-11) in piglets. Airway resistance increased from 5.0 (4.6-6.1) to 6.9 (5.8-7.9) kPa/L/s in rabbits only. Respiratory inductive plethysmography was used to measure the phase shift between the rib cage and abdominal compartment movements and the total compartmental displacement ratio. We aimed at unloading at least three-fourths of lung elastance in all animals and 2.0 kPa/L/s of resistance in rabbits. Elastic unloading decreased the phase shift in all but one animal. It reduced the total compartmental displacement ratio from 1.27 (1.14-3.73) to 1.16 (1.02-1.82) in piglets and from 1.77 (1.45-5.24) to 1.37 (1.11-4.78) in rabbits. The inspiratory rib cage expansion increased, whereas abdominal expansion did not. The tidal esophageal pressure deflection decreased. Tidal volume increased, whereas respiratory rate remained unaffected so that the partial pressure of arterial CO2 decreased. Resistive unloading as an adjunct to elastic unloading further reduced CWD and induced a more rapid, shallower breathing. We conclude that respiratory unloading as a mechanical support to spontaneous breathing reduces CWD. We speculate that the decrease in CWD increases ventilatory efficiency for a given diaphragmatic effort.

Topics: Abdomen; Animals; Animals, Newborn; Biomechanical Phenomena; Disease Models, Animal; Meconium; Rabbits; Respiration; Respiratory Mechanics; Swine; Thorax

To investigate the role of high frequency oscillation (HFO) in promoting meconium clearance from the airway, we used a commercially available ventilator configured with maximal expiratory flow exceeding inspiratory flow (asymmetric HFO or AHFO). We hypothesized that AHFO would move meconium in an expiratory direction (toward the ventilator). We first tested our hypothesis in vitro and, later, in vivo using the neonatal piglet. In vitro experiments using a Plexiglas airway confirmed meconium movement in an expiratory direction when bias ratio was > or = 2. For in vivo experiments, each piglet received a 3 mL/kg intratracheal bolus of a 44 g/100 mL meconium mixture followed by 45 min of mechanical ventilation. Then, in part 1, the piglet was placed in a 15 degree head down tilt position and randomized to either AHFO [ratio of inspiratory time/expiratory time (I:E) of 70:30] or HFO (I:E ratio of 30:70). After 30 min of either AHFO or HFO, the piglet was crossed over to the alternate strategy for an additional 30 min. For part 2, we maintained the piglet on either AHFO or HFO continuously for 4 h. Results demonstrate that, although there was a tendency for larger volumes of meconium to be aspirated from the airway during AHFO in part 1 experiments, there was no difference found in part 2. We also found no significant differences in blood gases or hemodynamic measurements between AHFO and HFO during the prolonged observation period in part 2 of our study. We conclude that AHFO is of no benefit in the treatment of meconium aspiration syndrome.

Topics: Animals; Animals, Newborn; Arteries; Blood Pressure; Carbon Dioxide; Cardiac Output; Disease Models, Animal; High-Frequency Ventilation; Humans; Hydrogen-Ion Concentration; In Vitro Techniques; Infant, Newborn; Lung; Meconium; Meconium Aspiration Syndrome; Partial Pressure; Swine

We have generated a mouse carrying the human G551D mutation in the cystic fibrosis transmembrane conductance regulator gene (CFTR) by a one-step gene targeting procedure. These mutant mice show cystic fibrosis pathology but have a reduced risk of fatal intestinal blockage compared with 'null' mutants, in keeping with the reduced incidence of meconium ileus in G551D patients. The G551D mutant mice show greatly reduced CFTR-related chloride transport, displaying activity intermediate between that of cftr(mlUNC) replacement ('null') and cftr(mlHGU) insertional (residual activity) mutants and equivalent to approximately 4% of wild-type CFTR activity. The long-term survival of these animals should provide an excellent model with which to study cystic fibrosis, and they illustrate the value of mouse models carrying relevant mutations for examining genotype-phenotype correlations.

Topics: Animals; Animals, Newborn; Base Sequence; Chlorides; Cystic Fibrosis; Cystic Fibrosis Transmembrane Conductance Regulator; Disease Models, Animal; DNA Primers; Electrophysiology; Gene Targeting; Genotype; Humans; Intestinal Obstruction; Ion Transport; Meconium; Mice; Mice, Transgenic; Molecular Sequence Data; Nasal Cavity; Phenotype; Point Mutation

Topics: Abdominal Muscles; Animals; Congenital Abnormalities; Disease Models, Animal; Fetal Diseases; Meconium; Rabbits; Urine

Recently we have created a mouse model of cystic fibrosis (CF) by insertional gene targeting to exon 10. In common with CF subjects, this model displays a low incidence of meconium ileus. This contrasts strikingly with the very high level of fatal intestinal obstruction in the three other CF mouse models so far described. We investigate here the molecular basis of this difference in phenotype. We show that the partial duplication consequent upon insertional gene targeting allows exon skipping and aberrant splicing to produce normal Cftr mRNA, but at levels greatly reduced compared with wild-type mice. Furthermore, instead of the predicted mutant Cftr transcript, a novel mRNA is produced that utilizes cryptic splice sites in the disrupting plasmid sequence. However, we have previously shown that these mice display the ion transport defect characteristic of CF, and mutant animals can be distinguished from their normal littermates on this basis. Consistent with this, residual CFTR function has recently been observed for several "mild" mutations in CF individuals who display pancreatic sufficiency but still develop lung disease. We conclude that (i) residual wild-type mRNA in the exon 10 insertional mutant mouse ameliorates the severity of the intestinal phenotype observed in the absolute "null" CF mice, (ii) the presence of low-level residual wild-type Cftr mRNA does not correct the CF ion transport defect, and (iii) the long-term survival of this insertional mutant mouse provides the opportunity to address the factors important in development of lung disease.

Topics: Animals; Animals, Newborn; Base Sequence; Cloning, Molecular; Cystic Fibrosis; Disease Models, Animal; DNA, Complementary; Exons; Gene Expression; Intestinal Obstruction; Lung; Meconium; Mice; Mice, Mutant Strains; Molecular Sequence Data; Mutagenesis, Insertional; Polymerase Chain Reaction; RNA, Messenger

Our purpose was to determine the acute-phase central hemodynamic and respiratory effects of raw, filtered, filtered and boiled, and meconium-containing amniotic fluid.. Pregnant goats (Capra hircus) in the last one third of pregnancy were given freshly collected autologous amniotic fluid in a volume of 2.5 ml/kg of body weight. Observations were then made at 10, 30, 60, 120, and 180 minutes after amniotic fluid embolism. Pulmonary artery catheters and femoral artery lung water catheters were placed for specimen and data collection.. Marked pressor responses were observed in both the pulmonary and systemic circulations with all amniotic fluid infusions. The pressor response was similar with raw, filtered, and filtered and boiled amniotic fluid. The pressor response seen with amniotic fluid containing meconium was significantly greater than that seen with the other forms. No significant effects were observed on cardiac or respiratory function except in the meconium group, where transient left ventricular dysfunction was accompanied by an acute increase in extravascular lung water and dysoxia.. The Capra hircus model is appropriate for the further study of amniotic fluid embolism. The acute pressor effects are transient and involve both the systemic and pulmonary circulations. Left ventricular dysfunction and dysoxia were observed only with embolism of amniotic fluid containing meconium.

Topics: Amniotic Fluid; Animals; Disease Models, Animal; Embolism; Female; Goats; Hemodynamics; Meconium; Pregnancy; Respiratory Mechanics

Cystic fibrosis results from defects in the gene encoding a cyclic adenosine monophosphate-dependent chloride ion channel known as the cystic fibrosis transmembrane conductance regulator (CFTR). To create an animal model for cystic fibrosis, mice were generated from embryonic stem cells in which the CFTR gene was disrupted by gene targeting. Mice homozygous for the disrupted gene display many features common to young human cystic fibrosis patients, including failure to thrive, meconium ileus, alteration of mucous and serous glands, and obstruction of glandlike structures with inspissated eosinophilic material. Death resulting from intestinal obstruction usually occurs before 40 days of age.

Topics: Animals; Cystic Fibrosis; Cystic Fibrosis Transmembrane Conductance Regulator; Digestive System; Disease Models, Animal; Exocrine Glands; Gallbladder; Genitalia, Male; Genotype; Growth; Intestinal Obstruction; Liver; Male; Meconium; Membrane Proteins; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mucus; Mutagenesis; Pancreas; RNA, Messenger; Salivary Glands

To compare high frequency positive pressure ventilation (HFV) to conventional ventilation (CV) in experimental meconium aspiration syndrome (MAS) adult rabbits were randomly assigned to one of four groups: sham (G1) n = 10, control (G2) n = 12, CV (G3) n = 6, and HFV (G4) n = 6. All animals were stabilized on an FI O2 of 0.70 after a tracheostomy and arterial line were placed. The alveolar-arterial oxygen difference (A-aDO2) was calculated for each blood gas measurement and mean airway pressure (MAP) measured in CV and HFV at the time of each blood gas. Human meconium (2 ml/kg of 25% solution) was instilled intratracheally (MI) in groups 2-4. Group 3 was then placed on conventional ventilation with a rate of 40 BPM while Group 4 with a rate of 400 BPM. Analysis of variance was used to compare A-aDO2 and MAP. There was no significant difference between group 4 and group 2, while there was a significant difference between group 3 and groups 2 and 4. Sustained inflation of 25 cm H2O as used for 20 seconds was used before HFV in a fifth group (n = 6) that was added to the study and was otherwise identical to HFV. There was no significant difference between the fifth group and group 2 or group 4. Our findings indicate HFV is not efficacious in experimental MAS whether or not sustained inflation is used.

Topics: Animals; Disease Models, Animal; Humans; Infant, Newborn; Infant, Newborn, Diseases; Inhalation; Intermittent Positive-Pressure Ventilation; Lung Diseases; Meconium; Oxygen; Positive-Pressure Respiration; Rabbits; Syndrome

The pulmonary and cardiovascular effects of high-frequency jet (HFJV) and conventional (CV) ventilation were evaluated in a piglet model of meconium aspiration. A mixture of 20% human meconium and 0.9% saline solution was instilled deep into the trachea of 10 piglets, after which either HFJV or CV was administered for 4 hours. Arterial blood gases, cardiac output, mean pulmonary and systemic arterial pressures, pulmonary and systemic vascular resistances, and pulmonary mechanics were compared between groups. During the 4 hours of ventilation, PaO2 and PaCO2 were not statistically different between groups. The peak inspiratory pressure necessary to maintain PaCO2 in the preset range was approximately half as much in the HFJV group as in the CV group (P less than 0.002). Mean airway pressure was lower in the HFJV group only during the second hour (P less than 0.03). Cardiac output, mean aortic and pulmonary artery pressures, systemic and pulmonary vascular resistance, dynamic lung compliance, and pulmonary resistance were not statistically different between groups. Our results suggest that HFJV may be more effective than CV in the early stages of meconium aspiration syndrome because HFJV allows more efficient ventilation and adequate oxygenation at lower peak inspiratory pressures.

Topics: Animals; Animals, Newborn; Disease Models, Animal; Hemodynamics; Humans; Infant, Newborn; Intermittent Positive-Pressure Breathing; Meconium; Pneumonia, Aspiration; Respiration, Artificial; Respiratory Function Tests; Swine

We compared rapid-rate ventilation using a conventional ventilator with slow-rate ventilation in the normal lung of 7 newborn pigs and in the diseased lung model instilled with 25% meconium solution into the trachea. The flow rate (7.5 1/min) and inspiratory:expiratory ratio (1:3) were kept constant during the experiments by using a constant-flow and time-cycled ventilator; the only change in settings was the rate. Transthoracic electrical impedance at end-expiration increased in the normal and in the diseased lung. Both mean intratracheal pressure and end-expiratory esophageal pressure increased significantly (p less than 0.05) in both models upon changing to rapid-rate ventilation. Following the increase in ventilatory rates from an initial frequency of 37.5 breaths/min to a rapid rate of 150 breaths/min, there was a significant rise in both PaO2 and PaCO2 in the normal and diseased lung models. Although rapid-rate ventilation was maintained for 1 h, the improvement in oxygenation progressively deteriorated and PaCO2 also increased further. This rise in PaCO2 returned to the control levels by decreasing ventilation to the initial rate of 37.5/min. This study demonstrates that rapid-rate ventilation using a constant-flow and time-cycled ventilator is inferior to slow-rate ventilation in the diseased lung model.

Topics: Animals; Animals, Newborn; Carbon Dioxide; Disease Models, Animal; Esophagus; Kinetics; Lung Diseases; Meconium; Oxygen; Pressure; Respiration, Artificial; Swine; Trachea

In order to define as effective a procedure as possible for the intra- and post-partum clearance of the upper airways of meconium contaminated infants, three methods of suction clearance, nasal, oral and combined nasal and oral, were carried out on each of five kittens aged between 17 to 19 weeks. There was an interval of at least one week between each investigation. The animals were anaesthetized with ketamine intramuscularly. The pressure changes during delivery were simulated using a compressed blood pressure cuff around the kittens thorax. During the first minute of thoracic compression Tc 99 labeled synthetic sputum was introduced into both the oro- and nasopharynx, then during the 2nd minute the instilled fluid was removed using a conventional extractor with mucus trap. Solely oral or solely nasal routes were used, suction was carried out for 60 secs, whereas when the combined technique was applied the oral and nasal cavities were cleared for only 30 secs each. At the end at the 2nd minute thoracic compression was released and a deep inspiration occurred. After five minutes the radioactivity remaining after suction was documented using a gamma-camera. We attempted to answer the following questions: How much mucus could be extracted with each different method, and where the remaining amount was later distributed? Nasal suction alone was found to be inefficient; using this route an average of 13% (only an eight of the amount instilled) could be removed. Oral suction led to the recovery of an average of 52% of the material instilled, the combined technique much as 56%. After re-establishment of spontaneous respiration, it could be clearly seen that, independent of the efficacy of the technique used, the majority of the remaining radioactivity (55 relative percent) is localized in the head and neck area. Absolute values are 45% for nasal suction, 26% for oral, and 24% for the combined oro-nasal route. The other part of the remaining radioactivity was found in the lung or in the stomach. It must be pointed out that the aspirate need not be disturbed in both of the parts, both the stomach and the lungs can be solely involved. Five minutes after spontaneous respiration had been resumed the lungs revealed only a centrally distributed radioactivity. This corresponds anatomically to the trachea and major bronchi. The peripheral area of the lungs was free of aspirate at this point in time.(ABSTRACT TRUNCATED AT 400 WORDS)

Topics: Airway Obstruction; Amniotic Fluid; Animals; Cats; Disease Models, Animal; Humans; Infant, Newborn; Inhalation; Meconium; Respiration; Suction

Topics: Animals; Blood Pressure; Carbon Dioxide; Disease Models, Animal; Extracorporeal Circulation; Female; Fetal Blood; Fetus; Heart-Lung Machine; Inhalation; Lung; Lung Compliance; Meconium; Oxygen; Partial Pressure; Pregnancy; Sheep; Syndrome

Meconium aspiration syndrome occurs more commonly in infants subjected to fetal distress. The baboon model was utilized to produce in utero aspiration of meconium in the presence of fetal acidosis. Fifteen fetal baboons underwent acute catheterization of the femoral artery and a Swan-Ganz balloon was placed in the maternal aorta. Meconium was added to the amniotic fluid and the balloon was repetitively inflated to produce hypoxemia in 3 fetuses and hypoxemia and acidosis in 4. Two fetuses served as controls and the balloon was not inflated. Acidosis alone was produced in 3 others by maternal cooling. Maternal administration of fentanyl, a narcotic analgesic and respiratory depressant drug, was found to reduce the degree of in utero meconium aspiration in 3 distressed fetuses by inhibiting gasping respirations. It is concluded that fetal respiratory depressants may be useful in this circumstance but only when expert resuscitative capability is present in the delivery room.

Topics: Animals; Disease Models, Animal; Female; Fetal Diseases; Inhalation; Meconium; Papio; Pregnancy; Respiration

After a short literature a review a comparison is made between the development of the human digestive tract during the second trimester of gestation and that of the chick embryo (Gallus domesticus) during the last week of incubation. The surgical procedure for chick embryosis is discussed in connection with the the study of the pathogenesis of small bowel atresia and meconium peritonitis. The results corroborate that the chick embryo is a valuable laboratory animal in experimental fetal surgery.

Topics: Animals; Chick Embryo; Disease Models, Animal; Female; Humans; Intestinal Atresia; Intestine, Small; Meconium; Peritonitis; Pregnancy; Pregnancy Trimester, Second

An animal model of meconium aspiration was developed to determine the efficacy of glucocorticoids in its treatment. Rabbit pups were made to aspirate either meconium or saline prior to the onset of respiration. Cortisol was administered in a random, blind fashion. Slight decrease in respiratory rate and less severe histopathologic changes in the lungs were seen in corticosteroid-treated animals. Survival was significantly decreased, without definite cause, in the glucocorticoid-treated animals whether or not they had aspirated meconium. Because of this decreased survival and the relatively insignificant improvement in clinical course and histopathology found with glucocorticoid treatment, we cannot recommend cortisol for the treatment of meconium aspiration.

Topics: Animals; Body Weight; Disease Models, Animal; Female; Humans; Hydrocortisone; Infant, Newborn; Infant, Newborn, Diseases; Inhalation; Lung; Meconium; Organ Size; Oxygen Consumption; Pregnancy; Rabbits; Sodium Chloride

Topics: Animals; Disease Models, Animal; Embolism, Amniotic Fluid; Female; Meconium; Pregnancy; Rats

Topics: Amino Sugars; Animals; Animals, Newborn; Diatrizoate; Disease Models, Animal; Dogs; Enema; Intestinal Obstruction; Meconium; Sorbitol

Topics: Animals; Disease Models, Animal; Dogs; Female; Humans; Infant, Newborn; Infant, Newborn, Diseases; Inhalation; Intubation, Intratracheal; Laparotomy; Meconium; Pregnancy; Radiography; Respiratory Tract Diseases; Uterus

Topics: Abruptio Placentae; Animals; Cardiac Output; Disease Models, Animal; Dye Dilution Technique; Embolism, Amniotic Fluid; Female; Fibrin; Humans; Latex; Male; Meconium; Methods; Microspheres; Placenta; Pregnancy; Rabbits; Radioisotopes; Retinal Vessels; Thrombin; Thromboplastin; Time Factors; Tissue Extracts; Xenon