pyrophosphate and calcium-phosphate--dibasic--anhydrous

Enamel of intact human teeth laser irradiated in vitro under certain conditions is known to have less subsurface demineralization than unirradiated enamel on exposure to acid; consequently, the potential use of laser irradiance to reduce caries is apparent. The laser-induced physical and/or chemical changes that cause this reduced subsurface demineralization are not known. A laser-irradiated tooth enamel surface will have a temperature gradient that decreases towards the dentin junction. Dependent on irradiant conditions, the temperature may range from greater than 1400 degrees C at the surface to near normal at the dentin-pulp junction. Along this steep temperature gradient, different compositional, structural, and phase changes in the tooth enamel are to be expected. Identification of changes occurring along this gradient has bearing on understanding the dissolution reduction mechanism and, in turn, optimizing its effect. Changes in laser-irradiated material from the highest temperature region have been characterized, but those occurring in sequential layers of decreasing temperatures have not. Since the laser-induced changes are expected to primarily arise from localized heating, previously reported thermally induced changes in tooth enamel on heating in conventional furnaces were utilized to infer corollary changes along the gradient in laser-irradiated tooth enamel. These thermally inferred changes which resulted in modifications in the tooth enamel apatite and/or newly formed phases were correlated with their probable effects on altering solubility. A temperature gradient range from 100-1600 degrees C was considered with subdivisions as follows: I, 100-650 degrees C; II, 650-1100 degrees C; and III, greater than 1100 degrees C. Two of the products formed in range III, alpha-Ca3(PO4)2 and Ca4(PO4)2O, and also identified in the fused-melted material from laser-irradiated tooth enamel, are expected to markedly increase solubility in those regions that contain considerable amounts of these compounds. Products and changes occurring in range II, separate phases of alpha- and/or beta-Ca3(PO4)2 and a modified phase of apatite, may increase or decrease the solubility depending on the Ca/P ratio and the resultant amounts of alpha-, beta-Ca3(PO4)2 formed. Modifications in tooth enamel apatite effected in range I are expected to decrease its solubility; the formation of pyrophosphate in this range may have a substantial effect on reducing the solubility rate.(A

Topics: Biological Transport, Active; Calcium Phosphates; Crystallization; Dental Enamel; Dental Enamel Solubility; Diphosphates; Durapatite; Fluorides; Hot Temperature; Humans; Hydroxyapatites; In Vitro Techniques; Lasers; Tooth Calcification

To test the hypothesis that anticalculus agents cannot completely inhibit calculus formation but can influence the types of calcium phosphate which form, i.e., they can influence the composition of the inorganic component of human dental calculus (HDC).. The composition of HDC specimens obtained from a 16-week multi-center clinical study using three regimens were analyzed, investigators blinded. The treatment regimens were: (a) standard dentifrice (SD), (b) pyrophosphate antitartar dentifrice, and (c) SD with Tartar Control Listerine Antiseptic mouthrinse (containing essential oils and 0.09% zinc chloride). 25 individual samples and eight pooled samples from each group were analyzed using X-ray diffraction, infrared spectroscopy, and scanning electron microscopy.. (1) relative frequency of occurrence for: (a) bacteria: Group A = 100%, Group B = 60%, and Group C = 25%; (b) Carbonate hydroxyapatite (CHA): Groups A, B, and C = 100%; (c) dicalcium phosphate dihydrate (DCPD): Group A = 55%; Group B = 45%; Group C = 80%; (2) The relative amount of DCPD is inversely proportional to that of CHA in HDC: the higher the amount of DCPD, the lower the amount of CHA. Group C regimen with essential oil/ZnCl2 mouthrinse and standard dentifrice showed a significant anti-microbial effect and favored the formation of DCPD, the most soluble Ca-P.

Topics: Anti-Infective Agents, Local; Bacteria; Calcium Phosphates; Chlorides; Dental Calculus; Dentifrices; Diphosphates; Double-Blind Method; Durapatite; Humans; Microscopy, Electron, Scanning; Mouthwashes; Oils, Volatile; Organic Chemicals; Spectroscopy, Fourier Transform Infrared; X-Ray Diffraction; Zinc Compounds

Experiments were performed to determine if a pyrophosphate-containing anticalculus toothpaste could affect certain salivary constituents involved in the mineralization of dental plaque. The findings indicated no obvious changes in acid and alkaline pyrophosphatases, ionized calcium, total calcium, inorganic phosphate or pH in saliva for 1-135 min after brushing the teeth with the anticalculus toothpaste. Data obtained by brushing with the toothpaste three times daily for two weeks also confirmed these results. Our findings clearly indicate that pyrophosphate-stabilizing agents in the anticalculus toothpaste are not fully effective in the oral cavity. In addition, the pyrophosphate-containing toothpaste has no influence on the state of calcium and phosphate in saliva.

Topics: Adult; Analysis of Variance; Calcium; Calcium Phosphates; Dental Calculus; Diphosphates; Female; Humans; Hydrogen-Ion Concentration; Male; Multivariate Analysis; Pyrophosphatases; Saliva; Single-Blind Method; Toothpastes

Coordinate regulation of fibrinolytic and collagenolytic systems is essential for normal tissue remodeling and wound healing. To define the molecular mechanisms which link these two proteolytic systems, we have investigated the role of fibrin in matrix metalloproteinase (MMP) function. Both active and latent forms of MMP-9 (gelatinase B) bind to fibrin in a selective, dose-dependent manner; latent enzyme is activated by plasmin during fibrinolysis. Fibrin binding of MMP-9 is mediated by amorphous calcium phosphate (ACP), and proceeds in a step-wise fashion with formation of ACP as the first and rate-limiting step. MMP-9 rapidly binds preformed ACP to yield a transient ACP: MMP-9 complex that avidly binds fibrin. Here we report the effect(s) on fibrin: ACP: MMP-9 formation/dissociation of pyrophosphate (POP), an endogenous calcification inhibitor, and its bisphosphonate analog, alendronate (PCP). MMP-9 was obtained from neutrophil lysate and ACP formation was monitored turbidimetrically. Free MMP-9, ACP: MMP-9 and fibrin: ACP: MMP-9 complexes were analyzed by gelatin zymography. POP at physiologic concentrations (0.5-2.5 microM) inhibited both ACP formation and subsequent fibrin binding of MMP-9 at orthophosphate concentrations of 250 microM. PCP exhibited a similar inhibitory effect. With both substances, inhibition was slightly overcome (>2.5 microM) by higher phosphate (500 microM). In contrast, supraphysiologic concentrations of either POP or PCP (>50 microM) were required to inhibit MMP-9 binding to preformed ACP or to induce dissociation of preformed ACP: MMP-9 complexes (50-100 microM). Neither POP nor PCP had any effect on preformed fibrin: ACP: MMP-9 at concentrations up 1 mM. POP is an endogenous by-product of numerous metabolic pathways and may regulate bone turnover, soft tissue calcification, and contribute to the pathogenesis of calcium pyrophosphate crystal disease (CPPD). These studies support another role for POP and fibrin: ACP: MMP-9 complexes in physiologic and pathologic processes, including tumorigenesis and cancer metastasis.

Topics: Binding, Competitive; Calcium Phosphates; Diphosphates; Diphosphonates; Fibrin; Humans; Macromolecular Substances; Matrix Metalloproteinase 9; Matrix Metalloproteinase Inhibitors; Protein Binding

Calcium phosphate cements can be handled in paste form and set in a wet medium after precipitation of calcium phosphate crystals in the implantation site. Depending on the products entering into the chemical reaction leading to the precipitation of calcium phosphates, different phases can be obtained with different mechanical properties, setting times and injectability. We tested a cement composed of a powder, containing beta-tricalcium phosphate (beta-TCP) and sodium pyrophosphate mixed with a solution of phosphoric and sulphuric acids. The cement set under a dicalcium phosphate dihydrate (DCPD)-based matrix containing beta-TCP particles. This was injected with a syringe into a defect drilled in rabbit condyles, the control being an identical defect left empty in the opposite condyle. The condyles were analysed histologically 2, 6 and 18 weeks after implantation. After injection into the bone defect the cement set and formed a porous calcium phosphate structure. Two different calcium phosphate phases with different solubility rates could be identified by scanning electron microscopy (SEM) observation. The less-soluble fragments could be degraded by cell phagocytosis in cell compartments of low pH or integrated in the newly formed bone matrix. The degradation rate of the material was relatively high but compatible with the ingrowth of bone trabeculae within the resorbing material. The ossification process was different from the creeping substitution occurring at the ceramic contact. Bone did not form directly at the cement surface following the differentiation of osteoblasts at the material surface. The trabeculae came to the material surface from the edges of the implantation site. Bone formation in the implantation site was significantly higher than in the control region during the first week of implantation. In conclusion, this material set in situ was well tolerated, inducing a mild foreign-body reaction, which did not impair its replacement by newly formed bone within a few weeks.

Topics: Animals; Biocompatible Materials; Bone Cements; Calcium Phosphates; Diphosphates; Female; Mandibular Condyle; Microscopy, Electron, Scanning; Osteoblasts; Prostheses and Implants; Prosthesis Implantation; Rabbits; Surface Properties; Time Factors

Phospho(enol)pyruvate (PEP) undergoes transphosphorylation to form pyrophosphate (PPi) and adenosine 5'-diphosphate (5'-ADP) with high yields in the presence of an adsorbent surface of calcium phosphate (Pi.Ca), which is considered to be an ancient mineral with catalytic properties. PPi formation is a result of the phosphorolytic cleavage of the enol phosphate group of PEP by precipitated Pi. The synthesis of PPi is dependent on the amount of the solid matrix; it increases with the amount of adsorbed PEP and upon addition of dimethyl sulfoxide (Me2SO), a molecule with high dipolar moment. Although it is saturated with PEP at neutral pH, the phosphorylating Pi.Ca surface becomes effective only in alkaline conditions. In a parallel reaction, PEP phosphorylates 5'-AMP to 5'-ADP with a yield that is sevenfold higher in the presence of the Pi.Ca surface than in its absence, indicating that the solid matrix promotes interaction between adsorbed molecules with a high potential for phosphoryl transfer. In contrast to phosphorolysis, this latter reaction is stimulated by Me2SO only in homogeneous solution. It is concluded that phosphate minerals may have coadjuvated in reactions involving different phosphorylated compounds and that molecules with high dipolar moment may have acted in mildly alkaline, primitive aqueous environments to modulate phosphoryl transfer reactions catalyzed by phosphate minerals.

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Adsorption; Calcium Phosphates; Catalysis; Dimethyl Sulfoxide; Diphosphates; Hydrogen-Ion Concentration; Phosphoenolpyruvate; Phosphorylation; Solubility

The formation of carbamyl phosphate (CAP) in dilute solutions of cyanate (NCO-) and orthophosphate (Pi) was measured both in the absence and in the presence of a precipitated matrix of calcium phosphate (Pi.Ca). The second-order rate constant and the free energy of CAP synthesis were not modified by the presence of the solid matrix, indicating that synthesis occurs in the homogeneous Pi-containing solution. The elimination reaction of CAP to form NCO- and Pi followed first-order kinetics and the rate constant was the same whether or not calcium phosphate was present. Elimination was not complete, and the steady level of remaining CAP was that expected from the free energy of synthesis. The formation of pyrophosphate (PPi) was detected in CAP-containing medium only in the presence of calcium, showing a close correlation with the amount of precipitated Pi.Ca. Phosphorolysis of CAP followed a sigmoidal time course, compatible with adsorption of CAP to the solid matrix as a prelude to transphosphorylation. Addition of 5'-AMP and of short linear polyphosphates inhibited phosphorolysis of CAP. It is proposed that the presence of a solid phosphate matrix and the relative concentrations of cyano compounds, as well as those of nucleotides and inorganic polyphosphates, could have played a crucial role in the conservation of chemical energy of CAP and in its use in prebiotic phosphorylation reactions.

Topics: Adenosine Monophosphate; Biopolymers; Calcium Phosphates; Carbamyl Phosphate; Chemical Precipitation; Crystallization; Cyanates; Diphosphates; Evolution, Chemical; Kinetics; Phosphates; Phosphorylation; Polyphosphates

A non-enzymatic formation of 5'-ADP starting from phosphorylation of 5'-AMP in the presence of either calcium phosphate or calcium pyrophosphate precipitates is reported. This reaction is taken as a model for the study of heterogeneous catalysis of transphosphorylation in prebiotic conditions. Experiments were performed in completely aqueous media and in media containing dimethyl sulfoxide (Me2SO), to simulate periods of dehydration in primitive aquatic environments. It has been observed that the nucleotide is adsorbed onto both calcium phosphate and calcium pyrophosphate in accordance with Langmuir isotherms. Adsorptive capacity and affinity of the precipitates for nucleotide are changed by the presence of Me2SO, suggesting that the interaction between biomonomers and surfaces can be modulated by the degree of hydration of the anionic components of these compounds. In completely aqueous environments, formation of 5'-ADP from 5'-AMP adsorbed on precipitates of calcium phosphate and calcium pyrophosphate is very small. However, in the presence of 60% Me2SO this synthesis increases by factors of 3 and 6 for surfaces of calcium phosphate and calcium pyrophosphate, respectively, and follows first-order kinetics. Determinations of free energy changes show that phosphorylation of 5'-AMP adsorbed to these precipitates is thermodynamically favorable. Depending on the precipitation time of the samples and the composition of the medium, structural analysis of these precipitates by electron and X-ray diffraction shows changes in their cristallinity grade. It is proposed that these changes are responsible for the modulation of the quantity of adsorbed nucleotides to the surface of solid matrices as well as the catalytic activity of the precipitates.

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Adsorption; Calcium Phosphates; Calcium Pyrophosphate; Chemical Precipitation; Dimethyl Sulfoxide; Diphosphates; Evolution, Chemical; Microscopy, Electron; Minerals; Phosphorylation; Thermodynamics; X-Ray Diffraction

The procedure for charring bone has been found to influence the nature of its mineral phase, and also affects the defluoridation capacity of the char. The aim of this study was to examine the efficiency of defluoridation by char produced from various parts of bones and charred for various lengths of time at various temperatures, relating the preparation of the char to its X-ray diffraction pattern, its content of pyrophosphate and its capacity for defluoridation. Bone was charred for 1 and 4 h at 400 degrees C and 30 min, 4 h and 48 h at 550 degrees C. Batches of the chars were suspended in amounts of 0.25 g in 100 ml of distilled water containing 0.53 mmol/l fluoride for up to 6 days under gentle agitation. At intervals, the pH and concentrations of fluoride, calcium and phosphate in the water were determined and the degree of saturation with respect to the calcium phosphate salts calculated. The charring procedure reduced the organic content of the bone from the 44-26% in intact bone to 3.4% in bone charred at 400 degrees C and to almost zero when charred at 550 degrees C for 48 h. When charred at 400 degrees C for up to 4 h the X-ray diffraction pattern of the bone showed a poorly crystallized apatite similar to that of untreated bone. Heating for 48 h or more at 550 degrees C led to considerably sharper apatite reflections, indicative of a well-crystallized salt.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Absorption; Animals; Apatites; Bone and Bones; Calcium; Calcium Phosphates; Carbon; Cattle; Charcoal; Crystallization; Crystallography; Diphosphates; Fluorides; Hot Temperature; Hydrogen-Ion Concentration; Ion Exchange; Phosphates; Solubility; Time Factors; Water; X-Ray Diffraction

This investigation tested and validated an in vitro model for studying the effects of fluoride on human dentin mineral content and fluoride uptake. Four studies examined the effects of different concentrations of fluoride, established dose-response profiles with NaF and Na2PO3F, and tested commercial dentifrices. A 7- or 14-day cyclic treatment regimen involved four 1-min exposures of sound human dentin specimens to the treatment agents, a 4-hour acid challenge period, and 20 h in human saliva daily. Mineral content was analyzed by image analysis microradiography and fluoride assays were performed using a microdrill biopsy technique. Data from these studies established the ability of the in vitro model to provide reproducible results, to demonstrate significant dose-related differences in the effects of both NaF- and Na2PO3F-containing treatments on dentin fluoride uptake and demineralization, and to detect a fluoride-induced reduction in dentin caries, relative to a nonfluoride control, similar to results established in a clinical trial.

Topics: Biopsy; Calcium Phosphates; Dental Calculus; Dentifrices; Dentin; Dentin Solubility; Diphosphates; Dose-Response Relationship, Drug; Fluorides; Humans; Image Processing, Computer-Assisted; Microradiography; Minerals; Models, Biological; Phosphates; Reproducibility of Results; Root Caries; Saliva; Silicon Dioxide; Sodium Fluoride; Tooth Demineralization

The promotion and the inhibition of hydroxyapatite formation by various substances were determined by measurement of the induction time of spontaneous precipitation (ti) from supersaturated solutions. Silica was found to decrease ti in Hepes-buffered (pH 7.2) supersaturated solutions with a wide range of calcium-to-phosphate ratios and concentrations. Also, in suspensions of the oral bacteria S. mutans or C. matruchotii in 1 mmol/L calcium, 7.5 mmol/L phosphate, and 50 mmol/L Hepes (pH 7.2), silica was capable of stimulating precipitation. Macromolecules derived from these bacteria by freezing and thawing appeared to be strong inhibitors of calcium phosphate precipitation. In the presence of silica, the effects of these bacterial inhibitors could be partially overcome, which supports the idea that silica in dental plaque is a promoter of calculus formation. In contrast, inhibition of calcium phosphate precipitation by a low-molecular-weight inhibitor, pyrophosphate, could not be counteracted by silica.

Topics: Bacterial Proteins; Calcium Phosphates; Carbohydrates; Chemical Precipitation; Corynebacterium; Crystallization; Diphosphates; Hydroxyapatites; Macromolecular Substances; Silicon Dioxide; Streptococcus mutans; Subcellular Fractions; X-Ray Diffraction

As some currently available toothpastes contain zinc compounds, the reaction of zinc with dental mineral and its effect on crystal growth rates were studied using three synthetic calcium-deficient hydroxyapatites (HAP) as being representative of dental mineral. Zinc was readily acquired by all HAP samples in the absence of added calcium, the amount adsorbed being proportional to the HAP surface area; about 9 mumol Zn/m2 was adsorbed at high zinc concentrations. As zinc was acquired, calcium was released, consistent with 1:1 Ca:Zn exchange. Soluble calcium reduced zinc uptake and similarly, calcium post-treatment released zinc. Pretreatment of HAP with 0.5 mM zinc reduced its subsequent ability to undergo seeded crystal growth, as did extracts of a toothpaste containing 0.5% zinc citrate, even in the presence of saliva. The reverse reaction, i.e. displacement of adsorbed zinc by salivary levels of calcium, however, indicates the mechanism by which zinc can reduce calculus formation in vivo by inhibiting plaque mineralisation without adversely affecting the anti-caries effects of fluoride.

Topics: Acetates; Acetic Acid; Adsorption; Aluminum Oxide; Calcium; Calcium Phosphates; Citrates; Citric Acid; Crystallization; Diphosphates; Durapatite; Fluorides; Humans; Hydroxyapatites; Phosphates; Saliva; Silicon Dioxide; Sodium Fluoride; Surface Properties; Toothpastes; Zinc

The possible inhibitors of heterogeneous nucleation were investigated. The effects of magnesium, pyrophosphate, citrate and Chondroitin Sulphate on calcium phosphate or uric acid heterogeneous nucleation of calcium oxalate were studied. It was found that whereas magnesium, pyrophosphate and citrate acted as effective inhibitors in the presence of calcium phosphate as heterogeneous nucleant, only chondroitin sulphate manifested important inhibitory effects when uric acid was the heterogeneous nucleant.

Topics: Calcium Oxalate; Calcium Phosphates; Chondroitin Sulfates; Citrates; Citric Acid; Crystallization; Diphosphates; Humans; Magnesium; Uric Acid; Urinary Calculi

Synovial fluid (SF) inorganic pyrophosphate (PPi) concentration is elevated in calcium pyrophosphate dihydrate (CPPD) crystal deposition arthropathy. Since CPPD and basic calcium phosphate (BCP) crystals often are present in the same joints, we determined [PPi] and activity of the PPi-generating enzyme, nucleotide pyrophosphohydrolase (NPPH), in SF from the joints of patients with various arthropathies, including those with BCP crystals. We found elevated SF [PPi] in joints with BCP crystals, as well as in joints with CPPD crystals. The presence of BCP crystals in synovial fluids was also predictive of elevated NPPH activity.

Topics: Calcium Phosphates; Crystallization; Diphosphates; Humans; Joint Diseases; Osmolar Concentration; Osteoarthritis; Preservation, Biological; Pyrophosphatases; Shoulder Joint; Syndrome; Synovial Fluid

A 49 year old man is described with a polyarticular arthritis. Synovial fluid aspirated from the knee joint showed monosodium urate monohydrate and calcium pyrophosphate dihydrate by polarised light microscopy. Additionally, diphosphonate binding and scanning electron microscopy with energy dispersive analysis showed that basic calcium phosphate crystals were also present. This appears to be the first report of three crystals occurring simultaneously in a single joint.

Topics: Arthritis; Calcium Phosphates; Calcium Pyrophosphate; Crystallization; Diphosphates; Humans; Knee Joint; Male; Middle Aged; Uric Acid

The adsorption of pyrophosphate, tin-pyrophosphate and 99mTc(Sn)pyrophosphate on Ca3(PO4)2 was investigated at pH 4.0 and pH 7.4. All components were radioactively labeled. Tin and reduced technetium were in most cases almost completely bound. The adsorption of pyrophosphate, tin(II) and technetium-99m at pH 4.0 was higher than at pH 7.4. The presence of tin gave rise to an increase of the pyrophosphate adsorption that was much larger than can be accounted for by a stoichiometric adsorption of tin-pyrophosphate. It is concluded that tin and technetium are bound as negatively charged complexes with pyrophosphate. Finally it is argued that the fraction of the bone scanning agent that reaches the bone surface is adsorbed completely by the mineral phase.

Topics: Adsorption; Binding Sites; Bone and Bones; Calcium Phosphates; Diphosphates; Humans; Hydrogen-Ion Concentration; In Vitro Techniques; Polyphosphates; Radionuclide Imaging; Technetium; Technetium Tc 99m Pyrophosphate; Tin; Tin Polyphosphates

Monosodium urate crystals are clearly related to acute attacks of gout and to the hard tissue destruction of chronic tophaceous gout. Fortunately, the acute attacks are readily treated with anti-inflammatory drugs, and destructive changes due to tophi may be prevented or reversed, at least in part, by the intelligent control of serum urate levels. Control of gout is one of the premier success stories of modern medicine. In contrast, the number of patients who have arthritis associated with crystals that contain calcium appears to be rising--perhaps a function of better recognition, perhaps related to the aging of the population. CPPD and BCP crystals can be associated with acute or subacute inflammation, but as in acute gout, it is easily controlled with anti-inflammatory drugs or by local injections of corticosteroids. A direct relationship of BCP and CPPD crystals to the associated destructive arthropathies has been hypothesized and is supported by clinical observations, animal studies, and in vivo experiments. Unlike gout, which is usually associated with a systemic metabolic abnormality (i.e., hyperuricemia), calcium crystals deposition seem to be a localized phenomenon, although numerous local sites in several joints are often involved in a given patient. Tissue degeneration in gout clearly follows (tophaceous) crystal deposition. Calcium crystal deposition may follow, rather than precede, destructive joint changes. Alternatively, both destructive changes and crystal deposition may derive independently from a common, still obscure, biochemical abnormality of joint tissues. P. A. Dieppe and colleagues believe that calcium crystal deposition follows either primary or secondary tissue degeneration but that the crystals exert a positive feedback effect (amplification loop) that accelerates degeneration. Each of those formulations of a pathogenetic role for crystals may be true in a given case, analogous to the etiology of primary and secondary forms of hyperuricemia and to sodium urate crystal deposition coexistent with osteoarthritis (tophus formation in Heberden's nodes). Conclusive proof of a significant role for BCP or CPPD crystals in the pathogenesis of human joint tissue damage depends on interrupting the postulated disease mechanism and showing that this prevents joint deterioration and leads to significant repair of existing damage. Our current position is somewhat analogous to that of our colleagues who had to contend with management of gouty a

Topics: Aged; Arthritis, Rheumatoid; Calcium Phosphates; Calcium Pyrophosphate; Crystallization; Diphosphates; Gout; Humans; Male; Middle Aged

Six children with inflammatory bowel disease and nephrolithiasis are reported. Their mean age at the passage of the first stone was 12.5 years and the mean duration of active inflammatory bowel disease was 34.5 months. Four had ulcerative colitis and two had Crohn's disease. In three patients, the onset of stone disease was associated with a flare in the bowel disease. Stone passage in four patients was accompanied by an increase in abdominal pain; three experienced gross hematuria. Stones from four of the patients were composed primarily of calcium phosphate; stones from the remaining patients contained uric acid and/or calcium oxalate. The pathogenesis of nephrolithiasis as it relates to inflammatory bowel disease is considered and an approach to therapy offered.

Topics: Adolescent; Calcium; Calcium Phosphates; Child; Citrates; Citric Acid; Colitis, Ulcerative; Crohn Disease; Crystallization; Diphosphates; Female; Humans; Kidney Calculi; Magnesium; Male; Oxalates; Oxalic Acid; Uric Acid

Four chemical buffers were evaluated with in vitro rumen fermentation studies using both an 80% concentrate and a 50% roughage diet. Treatments included a positive control (PC), negative control (NC) and four buffered diets in which 500 mg of either CaHPO4, CaCO3, NaHCO3 or Na4P2O7 were added. The PC consisted of unbuffered diet with one part rumen fluid and four parts McDougall's artificial saliva. In the unbuffered NC and buffered treatments, three-fourths of the artificial saliva was replaced by iso-osmotic saline. In the concentrate-based diet, NaHCO3 and Na4P2O7 elevated (P less than .05) pH above the NC. Starch digestion and total VFA were increased (P less than .05) by NaHCO3 compared with the NC while the molar proportion of individual VFA was not altered. Tetrasodium pyrophosphate had no effect on starch digestion or total VFA, but did increase (P less than .05) the molar proportion of acetic acid. Regarding the 50% roughage diet, both NaHCO3 and Na4P2O7 elevated (P less than .05) starch and cellulose digestion and total VFA compared with the NC. Both NaHCO3 and Na4P2O7 increased (P less than .05) the molar proportion of acetate to equal that of the PC. Tetrasodium pyrophosphate decreased (P less than .05) apparent starch digestion compared with the NC, but increased (P less than .05) the molar proportion of acetate. Compared with the NC, CaHPO4 and Na4P2O7 increased the quantity of microbial alpha-amino N in both diets. Soluble P was highly correlated with microbial protein synthesis in both the concentrate- and roughage-based diets (.92 and .90, respectively).

Topics: Ammonia; Animals; Bacteria; Bacterial Proteins; Bicarbonates; Buffers; Calcium Carbonate; Calcium Phosphates; Cattle; Cellulose; Dietary Fiber; Dietary Proteins; Digestion; Diphosphates; Fatty Acids, Volatile; Fermentation; Hydrogen-Ion Concentration; In Vitro Techniques; Nitrogen; Rumen; Sodium Bicarbonate; Starch

A method is described which determines the amount of calcium phosphate inhibitor activity in solutions with ionic compositions similar to that of undiluted plasma or serum. Constant supersaturations were obtained for the inhibitor analysis by equilibrating an aliquot of sample with dicalcium phosphate dihydrate (DCPD) and it was shown that the ion activity product of the equilibrated solutions was similar to the solubility product of DCPD. The amount of inhibitor activity in solution is assessed by determining the amount of hydroxylapatite seed needed for a predetermined rate of crystal growth. It was shown that the Langmuir adsorption isotherm is an appropriate model for describing the inhibitor data and provides a convenient linear-regression means for computing inhibitor activities. When tested at its normal physiological concentrations in plasma, albumin was the most important of the known calcium phosphate inhibitors.

Topics: Animals; Calcium; Calcium Phosphates; Chromatography; Citrates; Crystallization; Diphosphates; Magnesium; Models, Chemical; Molecular Weight; Phosphates; Rats; Serum Albumin; Solutions; Spectrophotometry; Ultrafiltration

Rat and human serum and plasma were shown to contain considerable amounts of calcium phosphate precipitation inhibitors. Two general classes of inhibiting molecules were observed for both species: high molecular weight (approx. 30 000-200 000) and low molecular weight (less than 1000). The high molecular weight components eluted from a Bio-Gel P-200 column in two peaks, one at approx. 158 000 and a broader peak at approx. 43 000. The identity of these inhibitors is unknown at present. Low molecular weight inhibitors include magnesium, pyrophosphate, and citrate ions and at least one unidentified component that coelutes with pyrophosphate and citrate on a Bio-Gel P-4 column. Quantitatively, most of the inhibitor activity resides in the high molecular weight components and it is possible that it is this activity which is responsible for maintaining the metastability of the circulating fluids. The role of the low molecular weight components may be to regulate calcification at sites inaccessible to high molecular weight molecules.

Topics: Animals; Calcification, Physiologic; Calcium Phosphates; Chemical Precipitation; Chromatography, Gel; Citrates; Citric Acid; Diphosphates; Humans; Magnesium; Molecular Weight; Rats