pectins and Stomach-Ulcer

The objective of this study was to evaluate the effect of a commercial feed supplement containing pectin-lecithin on squamous mucosa ulceration in horses exposed to an experimental ulceration model. Five mares were treated while five mares were controls for this crossover, blinded study. The mares were fed concentrates and hay and were stabled with a two-hour turn out per day for a period of four weeks. The pectin-lecithin complex was fed for the duration of the study on the treated group. At the end of a four-week period, all mares underwent a seven-day alternating feed deprivation (week 5). The study was repeated again after a four-week washout period. Gastroscopy was performed on days 1, 28 and 35 of the study and was digitally recorded. Independent evaluation of the recordings and scoring of the lesions using the Equine Gastric Ulcer Syndrome (EGUS), severity and number scores were performed by three experienced gastroscopists. The prevalence and severity of squamous ulcers significantly increased after intermittent feed deprivation (P<0.001). No significant effect of the treatment was observed (P>0.05). In this study, the addition of a commercially available pectin-lecithin complex to the feed of horses for five weeks did not prevent or minimise the risk for gastric ulceration of the squamous mucosa.

Topics: Animal Feed; Animals; Anti-Ulcer Agents; Cross-Over Studies; Dietary Supplements; Female; Gastric Mucosa; Horse Diseases; Horses; Pectins; Phosphatidylcholines; Stomach Ulcer; Treatment Outcome

The objectives of this study were to evaluate the effects of two commercial feed supplements, Egusin 250® [E-250] and Egusin SLH® [E-SLH], on gastric ulcer scores, gastric fluid pH, and blood gas values in stall-confined horses undergoing feed-deprivation.. Nine Thoroughbred horses were used in a three-period crossover study. For the three treatment groups, sweet feed was mixed with E-250, E-SLH, or nothing (control group) and fed twice daily. Horses were treated for 21 days, then an additional 7 days while on an alternating feed-deprivation model to induce or worsen ulcers (period one). In periods two and three, horses (n=6) were treated for an additional 7 days after feed-deprivation. Gastroscopies were performed on day -1 (n=9), day 21 (n=9), day 28 (n=9) and day 35 (n=6). Gastric juice pH was measured and gastric ulcer scores were assigned. Venous blood gas values were also measured.. Gastric ulcers in control horses significantly decreased after 21 days, but there was no difference in ulcer scores when compared to the Egusin® treated horses. NG gastric ulcer scores significantly increased in E-250 and control horses on day 28 compared to day 21 as a result of intermittent feed-deprivation, but no treatment effect was observed. NG ulcer scores remained high in the control group but significantly decreased in the E-SLH- and E-250-treated horses by day 35. Gastric juice pH values were low and variable and no treatment effect was observed. Mean blood pCO2 values were significantly increased two hours after feeding in treated horses compared to controls, whereas mean blood TCO2 values increased in the 24 hour sample, but did not exceed 38 mmol/l.. The feed-deprivation model increased NG gastric ulcer severity in the horses. However, by day 35, Egusin® treated horses had less severe NG gastric ulcers compared to untreated control horses. After 35 days, Egusin® products tested here ameliorate the severity of gastric ulcers in stall-confined horses after feed stress.

Topics: Animal Feed; Animals; Antacids; Body Fluids; Cross-Over Studies; Dietary Supplements; Horse Diseases; Horses; Hydrogen-Ion Concentration; Lecithins; Oxygen; Pectins; Stomach Ulcer; Stress, Physiological

The severity of the erosive and ulcerative lesions of the squamous gastric mucosa in 10 standardbred racehorses in training was classified according to a standard scoring system. Each horse was then treated orally for 30 days with 50 g/100 kg bodyweight daily of a pectin-lecithin complex mixed into the feed. At the end of the period of treatment, the gastric lesions were re-evaluated gastroscopically and the scores were compared with those assigned at the previous evaluation. In three of the horses the gastric ulcerations had healed completely, and in six others the lesions had improved significantly.

Topics: Animals; Female; Horse Diseases; Horses; Male; Pectins; Phosphatidylcholines; Physical Exertion; Stomach; Stomach Ulcer

This study compared the study of a pectin-lecithin complex (Pronutrin) on gastric ulcer healing during an 11 day period in 2 groups of 12 horses each. Twenty-four horses suffering from gastric lesions of differing severity were selected from a larger group of clinical cases on the basis of gastroscopic examination. Both gastric mucosal erosions as well as gastric ulcers were found in the 2 mucosal regions (pars nonglandularis and pars glandularis). The gastric mucosal lesions occurred predominantly in the pars nonglandularis in the vicinity of the margo plicatus. The 24 horses were divided equally into a treated group (Group A) and a control group (Group B). Twelve horses in Group A received Pronutrin, in a dose of 300 g/horse/day over a period of 10 days, whereas horses in Group B received no active substance. Gastroscopic examination was performed on Days 0 and 11. The degree of severity of the gastric erosions or gastric ulcers was evaluated independently in the 2 mucosal regions with the aid of a scoring system. Group A horses showed good acceptance of the product and no side effects were recorded. After the 10 day treatment phase, Group A showed a marked reduction in gastric mucosal lesions or disappearance of lesions, while untreated horses showed no change or, even, a deterioration on Day 11. Statistical calculation of efficacy revealed a highly significant reduction in gastric mucosal lesions in the pars nonglandularis and a significant reduction in gastric mucosal lesions in the pars glandularis in the treated horses. It would appear, however, that the treatment period of 10 days was too short, since the gastric mucosal lesions had often not completely healed in all horses. The results of this study in 24 horses with gastric lesions suggest that a pectin-lecithin complex can have a beneficial effect on the healing of gastric ulcers.

Topics: Animals; Anti-Ulcer Agents; Female; Gastroscopy; Horse Diseases; Horses; Lectins; Male; Pectins; Phosphatidylcholines; Severity of Illness Index; Stomach Ulcer; Treatment Outcome

A peptic ulcer is an alimentary tract injury that leads to a mucosal defect reaching the submucosa. This work aimed to optimize and maximize ellagic acid (EA) loading in Ca pectinate floating beads to maximize the release for 24 h. Three factors were selected: Ca pectinate concentration (X1, 1-3 w/v %), EA concentration (X2, 1-3 w/v %) and the dropping time (X3, 10-30 min). The factorial design proposed eight formulations. The optimized EA-Ca pectinate formulation was evaluated for the gastric ulcer index and the oxidative stress parameter determination of gastric mucosa. The results indicated that the optimum EA-Ca pectinate formula significantly improved the gastric ulcer index in comparison with raw EA. The protective effect of the optimized EA-Ca pectinate formula was further indicated by the histopathological features of the stomach. The results of the study indicate that an EA formulation in the form of Ca pectinate beads would be effective for protection against gastric ulcers because of Nonsteroidal anti-inflammatory drugs (NSAID) administration.

Topics: Animals; Disease Models, Animal; Ellagic Acid; Indomethacin; Male; Oxidative Stress; Particle Size; Pectins; Rats; Stomach Ulcer; Treatment Outcome

In order to optimize drug action, new drug formulations have been developed based upon the prodrug approach. This study was inspired by the increasing interest in the field of macromolecular prodrugs and Piroxicam maleate was used as a model drug. A total of five prodrugs were synthesized using beta cyclodextrin, chitosan, pectin, egg albumin, bovine serum albumin. The synthesized conjugates were characterized on the basis of UV, IR and NMR techniques. In-vitro hydrolysis studies were carried out at pH 1.2, pH 7.4, pH 9.0 and in 80% human plasma followed by in-vivo evaluation of analgesic, anti-inflammatory and anti-ulcerogenic potential. The extent of hydrolysis was found to be proportional to increase in pH. Beta cyclodextrin conjugate was found to possess significant analgesic activity whereas chitosan conjugate was found to be the best anti-inflammatory. Pectin conjugate provided maximum protection against ulcers.

Topics: Albumins; Animals; beta-Cyclodextrins; Cattle; Chemistry Techniques, Synthetic; Chitosan; Cytoprotection; Drug Compounding; Female; Humans; Hydrogen-Ion Concentration; Hydrolysis; Male; Mice; Pectins; Piroxicam; Prodrugs; Rats; Stomach; Stomach Ulcer

The aim of this study was to investigate the chemical structure and biological activity of a pectic fraction isolated from the aerial parts of A. campestris L. subsp. maritima Arcangeli. The chemical and spectroscopic analyses of the pectic fraction (ACP-E10) demonstrated that ACP-E10 was composed of homogalacturonan (HG) (60%) and rhamnogalacturonan-I (RG-I) (29%) regions. Side chains of the RG-I included mainly branched arabinans and type II arabinogalactans (AG-II). The molar mass of ACP-E10 determined by HPSEC-MALLS was 16,600g/mol. ACP-E10 was evaluated for its gastroprotective effect against ethanol-induced gastric lesions in rats. Oral pretreatment of animals with ACP-E10 (0.3, 3 and 30mg/kg) significantly reduced gastric lesions by 77±7.9%, 55±11.1% and 65±11.8%. ACP-E10 also maintained mucus and glutathione (GSH) contents in the gastric mucosa. In addition, ACP-E10 demonstrated antioxidant activity in vitro by the DPPH assay. These results demonstrated that the pectin from A. campestris had significant gastroprotective effects in vivo, which were likely attributable to their capacity to increase the protective defenses of gastric mucosa.

Topics: Animals; Anti-Ulcer Agents; Artemisia; Ethanol; Gastric Mucosa; Humans; Mucoproteins; Pectins; Phytotherapy; Plant Leaves; Plant Proteins; Polysaccharides; Rats; Stomach Ulcer

Sedum dendroideum, popularly known in Brazil as balsam, is traditionally used as a wound healing agent, to treat gastritis, and several other health problems. Some studies have shown that plant polysaccharides may have gastroprotective properties.. Considering the popular use of S. dendroideum and the gastroprotective activity of polysaccharides, the objective of this work was to obtain, to characterize, and to evaluate the gastroprotective activity of a polysaccharide fraction from this plant.. Polysaccharides of S. dendroideum were extracted with water by infusion, fractionated by freeze-thawing process and dialyzed at a 100 kDa cut-off membrane, and characterized by monosaccharide composition and NMR analysis. The gastroprotective activity of the pectic polysaccharide fraction RSBAL was evaluated in the ethanol-induced ulcer model in rats, followed by determination of the mucus and glutathione levels in the gastric tissue.. RSBAL was constituted by a homogalacturonan and a homogalacturonan branched by side chains of arabinans and type II arabinogalactans. It reduced ethanol-induced gastric ulcers in rats, preserving mucus and glutathione levels in the stomach.. This study demonstrated that polysaccharides could be related to the pharmacological activity of S. dendroideum.

Topics: Animals; Anti-Ulcer Agents; Brazil; Ethanol; Female; Gastric Mucosa; Glutathione; Pectins; Plant Extracts; Plant Leaves; Plants, Medicinal; Polysaccharides; Protective Agents; Rats, Wistar; Sedum; Stomach Ulcer

Currently available anti-ulcer drugs suffer from serious side effects which limited their uses and prompted the need to search for a safe and efficient new anti-ulcer agent. Boswellia gum resin (BR) emerged as a safe, efficient, natural, and economic potential cytoprotective agent. Thus, it is of medical importance to develop gastroretentive (GR) formulations of BR to enhance its bioavailability and anti-ulcer efficacy. Early attempts involved the use of organic solvents and non-applicability to large-scale production. In this study, different tablet formulations were prepared by simple direct compression combining floating and bioadhesion mechanisms employing hydroxypropyl methylcellulose (HPMC), sodium carboxymethyl cellulose (SCMC), pectin (PC), and/or carbopol (CP) as bioadhesive polymers and sodium bicarbonate (SB) as a gas former. The prepared tablets were subjected for assessment of swelling, floating, bioadhesion, and drug release in 0.1 N HCl. The optimized GR formulation was examined for its protective effect on the gastric ulcer induced by indomethacin in albino rabbits compared with lactose tablets. The obtained results disclosed that swelling, floating, bioadhesion, and drug release of the GR tablets of BR depend mainly on the nature of the matrix and the ratio of polymer combinations. Moreover, a combination of SCMC-CP in a ratio of 2:1 (SCP21) exhibited desirable floating, bioadhesion, swelling, and extended drug release. Also, a 6-h pretreatment with SCP21 tablets decreased the severity of inflammation and number of bleeding spots among ulcer-induced rabbits in comparison to those treated with lactose tablets.

Topics: Acrylic Resins; Animals; Anti-Ulcer Agents; Biological Availability; Boswellia; Carboxymethylcellulose Sodium; Chemistry, Pharmaceutical; Drug Liberation; Excipients; Hypromellose Derivatives; Indomethacin; Male; Pectins; Polymers; Protective Agents; Rabbits; Resins, Plant; Sodium Bicarbonate; Stomach Ulcer; Tablets

Native, intact (TrPP) and modified, low-molecular-weight (MTrPP) forms of pectic polysaccharides isolated from turmeric were evaluated for ulcer-preventive potentials in in vitro and in vivo models. Data indicated that MTrPP possessed significantly better ulcer-preventive property than TrPP; inhibiting ulcer scores up to 85%. Results were substantiated by effective muco-protection, H(+),K(+)-ATPase down-regulation, inhibition of H. pylori growth/adherence, higher antioxidant/cytoprotective mechanisms. Structural data indicated TrPP and MTrPP differ in their molecular weights and structural characteristics with different sugar compositions and side chain ratios. MTrPP was rich in galacturonic acid (687mg/g; TrPP-544mg/g) and galactose (52.9%; TrPP-21.7%). Results were substantiated by NMR/FTIR data indicating the presence of homogalacturonan and rhamnogalacturonam-I containing galactans. By virtue of binding to inflammatory marker (galectin-3), galactans may reduce inflammation induced ulcerations. The low molecular weight of MTrPP (155kDa; TrPP-13kDa) may increase its bioavailability than TrPP, thus MTrPP may possess higher antiulcer potential.

Topics: Anti-Ulcer Agents; Antioxidants; Cell Line; Curcuma; Down-Regulation; Galactose; Gastric Mucosa; H(+)-K(+)-Exchanging ATPase; Helicobacter pylori; Hexuronic Acids; Humans; Magnetic Resonance Spectroscopy; Molecular Weight; Pectins; Polysaccharides; Spectroscopy, Fourier Transform Infrared; Stomach Ulcer

A rhamnogalacturonan (RGal) isolated from Acmella oleracea (L.) R.K. Jansen administered by oral route showed gastroprotective activity against acute lesions induced by ethanol. In this study, we investigated the gastric ulcer healing effect of RGal and its mechanisms of action. Intraperitoneal treatment of animals with RGal protected the gastric mucosa against acute lesions induced by ethanol, with participation of gastric mucus. Furthermore, in the chronic ulcer model, oral administration of RGal accelerates the gastric ulcer healing, accompanied by increasing of cellular proliferation and gastric mucus content, reducing inflammatory parameters and oxidative stress. In addition, the repeated 7 days-treatment of animals with RGal did not show alterations of clinical and behavioral symptoms, body and organs weights or plasmatic biochemical parameters. Collectively, these results showed that RGal has an interesting antiulcerogenic activity and could constitute an attractive molecule of interest for the development of new antiulcer agents.

Topics: Acetic Acid; Animals; Anti-Ulcer Agents; Antioxidants; Asteraceae; Body Weight; Cell Proliferation; Cytoprotection; Ethanol; Female; Gastric Acid; Gastric Mucosa; Glutathione; Mucins; Organ Size; Pectins; Rats; Rats, Wistar; Stomach; Stomach Ulcer

In Malian traditional medicine infusions of the roots of Vernonia kotschyana or Cochlospermum tinctorium in water are used for treating gastric ulcer. Helicobacter pylori is known to play a major role in gastric ulcer development, and it was of interest to evaluate a potential anti-adhesive activity towards H. pylori by crude water extracts and isolated polysaccharide fractions from the roots of V. kotschyana and C. tinctorium. The inhibitory effects were examined by an in vitro flow cytometric assay using human gastric adenocarcinoma epithelial cells, where fluorescent-labeled H. pylori were pre-treated with the test fractions. The crude extract Ctw50 from C. tinctorium, containing a mixture of inulin, pectic polysaccharides, phenols and protein, led to a 43% reduction of bacterial attachment. The isolated pectic type fractions CtwA1 and CtwA2 from C. tinctorium, and Vko-I from V. kotschyana resulted in approximately 30% inhibition of H. pylori adhesion. These fractions consist of rhamnogalacturonan backbones with side chains of arabinogalactans and/or arabinans. The low degree of uronic acids in the fractions compared to anti-adhesive polysaccharides reported previously, suggests that the neutral side chains might play a role in the binding of bacterial adhesins. The fraction Vko-III.1 from V. kotschyana consisting mainly of galacturonic acid resulted only in a 19% inhibition of H. pylori adhesion. The anti-adhesive properties shown by the crude water extracts and isolated polysaccharide fractions in the present study might partly explain the anti-ulcer activities by the roots of V. kotschyana and C. tinctorium.

Topics: Adenocarcinoma; Bixaceae; Cell Adhesion; Epithelial Cells; Galactans; Helicobacter pylori; Humans; Medicine, Traditional; Pectins; Phenols; Plant Extracts; Plant Roots; Polysaccharides; Stomach Ulcer; Vernonia

The plant Acmella oleracea (L.) R.K.Jansen (Asteraceae), locally known as jambu, is widely used in Legal Amazon in local dishes and in folk medicine. A polysaccharide (SC) was isolated from this plant, following aqueous extraction, which contained uronic acid, galactose, arabinose, rhamnose, and glucose in a 15:2:1:1:0.5 molar ratio and had a M(w) 226,000 g/mol. Methylation analysis and NMR spectroscopy indicated that SC is a rhamnogalacturonan composed of a long chain of →4)-6-OMe-α-D-GalpA-(1→, interspersed with some α-L-Rhap residues, partly substituted by side-chains of type II arabinogalactans. SC significantly inhibited ethanol-induced gastric ulcers in rats with an ED₅₀ of 1.5 mg/kg, indicating that SC acts as gastroprotective agent.

Topics: Animals; Anti-Ulcer Agents; Asteraceae; Chromatography, Ion Exchange; Female; Magnetic Resonance Spectroscopy; Pectins; Rats; Rats, Wistar; Stomach Ulcer

Standard models of experimental ulceration (of neurogenic origin, H. Shay ulcer, indomethacine-, ethanol-, prednisolone-, histamine- and acetate-induced ulcers) were used to demonstrate protective effect of non-starch polysaccharides (potassium alginate, potassium pectate, low-esterified pectin). Potassium pectate proved to be the most efficacious protector. Mechanism of its anti-ulcerative action is attributable to antacidic, cytoprotective, and reparative activity. It appeals to optimally stimulate the motor-evacuation function and, besides, exhibits marked anti-inflammatory activity.

Topics: Administration, Oral; Alginates; Animals; Antidiarrheals; Biocompatible Materials; Disease Models, Animal; Drug Carriers; Female; Gastric Emptying; Glucuronic Acid; Hexuronic Acids; Male; Mice; Pectins; Polysaccharides; Rats; Rats, Wistar; Stomach Ulcer; Treatment Outcome

Opuntia ficus indica cladodes possess a protective action against ethanol-induced ulcer in the rat. The major components of cladodes are carbohydrate polymers, mainly mucilages and pectin. To clarify the cytoprotective effects of cladodes on experimental ethanol-induced ulcer in rat, mucilages and pectin were extracted and were administered instead of cladodes. The above mentioned effects induced by cladodes may be attributed to mucilages, and not significantly to pectin.

Topics: Adhesives; Animals; Cytoprotection; Gastric Mucosa; Male; Opuntia; Pectins; Phytotherapy; Plant Extracts; Rats; Rats, Wistar; Stomach; Stomach Ulcer

This study examined whether a product containing a pectinlecithin complex (Pronutrin) (1) could prevent gastric lesions induced in the equine gastric squamous epithelial mucosa using a protocol of intermittent feed deprivation that resulted in prolonged increased gastric acidity (Murray and Eichorn 1996). Eight ponies were used and served as their own controls in 2 trials in which there were 72 h cumulative deprivation (alternating 24 h with no feed, then 24 h free choice hay), with a 4-week interval between trials. Ponies were assigned randomly to receive either 250 g Pronutrin plus 200 g pelleted feed, or 450 g pelleted feed only. Ponies were conditioned to each treatment for 7 days and received Pronutrin and pellets or only pellets once daily during the feed deprivation protocol. Gastroscopy was performed at the beginning and conclusion of the feed deprivation protocol. The endoscopist (MJ.M.) was blinded as to treatments, and lesion severity was scored on a scale of 0-5. Gastroscopy revealed normal-appearing gastric mucosa at the beginning of feed deprivation, with the exception of 2 ponies which had focal squamous mucosal erosion and 1 pony with focal glandular mucosal erosion. After 72 h cumulative feed deprivation, each pony, except 1 pony in one of the trials, developed erosions or ulcers in the gastric squamous mucosa. There was no difference (P = 0.6) in the presence or severity of gastric lesions between treatments. Lesions did not develop in the gastric glandular mucosa as a result of the intermittent feed deprivation with either treatment. In this study, the pectin-lecithin complex in Pronutrin failed to prevent lesions in the gastric squamous mucosa induced by intermittent feed deprivation.

Topics: Animals; Anti-Ulcer Agents; Female; Food Deprivation; Gastric Acid; Gastric Mucosa; Gastroscopy; Horse Diseases; Horses; Lectins; Male; Pectins; Phosphatidylcholines; Random Allocation; Severity of Illness Index; Stomach Ulcer

This study examined the role of oxygen-derived free radicals in the pathogenesis of gastric mucosal lesions induced by HCl/ethanol. Superoxide dismutase, and catalase, and their combination reduced gastric lesion formation in mice. Gastric lesions were also reduced in mice treated with cyclophosphamide or anti-neutrophils, but not in mice treated with allopurinol or desulphated-carrageenan. Cobra venom factor did not reduce lesion formation. These results suggested that oxygen-free radicals may contribute to the formation of gastric mucosal lesions induced by HCl/ethanol, and that oxygen radicals were generated from neutrophils but not from xanthine oxidase. Anti-ulcer pectic polysaccharide, bupleuran 2IIc, which was recently isolated from the roots of Bupleurum falcatum L., showed potent inhibition of HCl/ethanol-induced gastric lesions in mice. Bupleuran 2IIc seemed to scavenge hydroxyl radical effectively. It was suggested that this anti-ulcer polysaccharide may provide protection to the gastric mucosa by scavenging oxygen-free radicals.

Topics: Allopurinol; Animals; Anti-Ulcer Agents; Carrageenan; Cattle; Cyclophosphamide; Ethanol; Free Radical Scavengers; Gastric Mucosa; Hydrochloric Acid; Hydroxides; Hydroxyl Radical; Male; Mice; Mice, Inbred ICR; Neutrophils; Pectins; Rabbits; Reactive Oxygen Species; Stomach Ulcer; Superoxides

The protective capacities of fresh green (unripe) sweet bananas and of phosphatidylcholine and pectin (banana ingredients) against acute (ethanol- or indomethacin-induced) and chronic (indomethacin-induced) gastric mucosal lesions were evaluated in rats. Banana pulp was mixed with saline and given by gavage, as a pretreatment in a single dose. The identical protocol was used for pectin and phosphatidylcholine solution, and the dosages were adjusted to equal the amount of ingredients in the banana mixture, but higher concentrations were also given. The banana suspension reduced acute lesions, as did pectin and phosphatidylcholine in higher concentrations, but in concentrations as in fresh fruit no protective effects were observed except by pectin against indomethacin injury. In the model of chronic ulcers the banana suspension provided an incomplete and temporary protective effect. We conclude that the protective capacity of fresh green sweet bananas cannot be confined to only one active component. Pectin and phosphatidylcholine may protect gastric mucosa by strengthening the mucous-phospholipid layer, but the mechanism of protection afforded by bananas has to be further elucidated.

Topics: Acute Disease; Animals; Chronic Disease; Ethanol; Fruit; Gastric Mucosa; Indomethacin; Male; Models, Biological; Pectins; Phosphatidylcholines; Rats; Rats, Sprague-Dawley; Stomach Ulcer; Suspensions

Topics: Animals; Anti-Ulcer Agents; Chondroitin Sulfates; Dextrins; Female; Heparin; Male; Panax; Pectins; Plants, Medicinal; Polysaccharides; Rats; Stomach Ulcer

Topics: Diethylstilbestrol; Duodenal Ulcer; Endoscopy; Estriol; Glycyrrhiza; Humans; Parasympatholytics; Pectins; Peptic Ulcer; Plants, Medicinal; Radiography; Stomach Ulcer; Terpenes

Topics: Animals; Carbon Isotopes; Feces; Female; Glucose; Hydrocortisone; Intestinal Absorption; Intestinal Mucosa; Intestines; Methods; Oxytetracycline; Pectins; Rats; Stomach Ulcer; Sulfaguanidine; Sulfates; Sulfur Isotopes; Time Factors