Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0847097 (acidity)
 15,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The migration of lymphocytes through extracellular matrix (ECM) is an essential feature of the infiltration process. In the course of their extravasation into poorly perfused neoplastic lesions, lymphocytes often encounter regions of acidified ECM. This study was designed to determine whether lymphocyte adherence and motility in ECM are influenced by ambient pH. Murine splenic lymphocytes, activated by culture with high-titer IL-2, were allowed to migrate into three-dimensional gels of Type I collagen, a major component of interstitial stroma, or into Matrigel, a basement membrane model. After 18 hr at pH 7.1, the leading cell front traveled a mean distance of approx 475 microM into Type I collagen gel. Approx 50% of the cells remained nonadherent, 25% adhered to the gel surface, and 25% were motile (penetrated beneath the surface). At pH 6.7, the leading-front distance increased significantly, by a factor of 1.4X, but there was little change in the proportion of cells exhibiting nonadherence, surface adherence, or motility. The relative motilities of CD3+ and AsGM1+ subsets were also unaltered. It therefore appears that acidification of collagen matrix increases the locomotory activity of motile lymphocytes, but causes little recruitment of nonmotile lymphocytes into the motile pool. Similar results were obtained in experiments with Matrigel. The increased motility observed at pH 6.7 did not reflect breakdown or relaxation of matrix lattices, as measured by the passive diffusion of latex beads of defined diameter. Preincubation of lymphocytes at pH 6.7 did not alter their subsequent motility in pH 7.1 gels. The findings establish ambient pH as a microenvironmental variable which can influence lymphocyte migration through ECM. The weak acidity characteristic of certain tumor microenvironments may be a factor which encourages lymphocyte infiltration through tissue matrix. Treatments which alter intratumor pH could potentially be used to manipulate the infiltration process for immunotherapeutic benefit.
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PMID:Motility of IL-2-stimulated lymphocytes in neutral and acidified extracellular matrix. 173 11

Rats were concurrently exposed to mixtures of ozone or nitrogen dioxide and respirable-sized aerosols of sulfuric acid, ammonium sulfate, or sodium chloride, or to each pollutant individually. Their responses to such exposures were evaluated by various quantitative biochemical analyses of lung tissue or lavage fluids, or by morphometric analyses. Such studies were performed in the acute time frame, generally involving exposures of from one to nine days, depending on the assays used. Correlations between the biochemical and morphometric results were examined over a wide range of pollutant concentrations in the exposure chambers. Good correlations were found between the most sensitive biochemical indicators of lung damage--the protein content of lung lavage fluid or whole lung tissue and the rate of lung collagen synthesis--and the morphometric estimation of volume density or volume percent of the centriacinar lung lesion characteristically observed in animals exposed to ozone. Synergistic interaction between ozone and sulfuric acid aerosol was demonstrated to occur at environmentally relevant concentrations of both pollutants by several of the analytical methods used. Such interactions were demonstrated at concentrations of ozone as low as 0.12 parts per million (ppm)2 and of sulfuric acid aerosol at concentrations as low as 5 to 20 micrograms/m3. The acidity of the aerosol is a necessary (and apparently a sufficient) condition for such a synergistic interaction between an oxidant gas and a respirable aerosol to occur. A hitherto unexpected synergistic interaction between nitrogen dioxide and sodium chloride aerosol was found during these studies; it is hypothesized that this was due to formation of their acidic (anhydride) reaction product, nitrosyl chloride, in the chambers during exposure to the mixture. Preliminary experiments treating exposed animals in vivo with various free-radical scavengers suggested that dimethylthiourea, a hydroxyl-radical scavenger, might be protective against effects of ozone on rat lungs. This observation might have mechanistic implications, but further studies will be necessary to determine the significance of these findings.
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PMID:Synergistic effects of air pollutants: ozone plus a respirable aerosol. 201 83

N-acetylcysteine, a mucolytic expectorant, was used for debridement of a full-thickness burn in rabbits. The drug was applied 24h postburn and repeated once a day. Debridement was completed in an average of 2.25 days with bloodless separation of any remaining eschar from the underlying healthy deep fascia layer by blunt dissection with a forceps. In the wounds treated with 25% N-acetylcysteine(pH 2.5), debridement was faster than those treated with glacial acetic acid mixture at the same pH. The debriding action of the drug is probably depolymerization of heat-denatured extracellular proteins (mainly denatured collagen and proteoglycans), disrupting specific linkage and lowering the molecular weight of eschar molecules. Acidity of the drug also promotes debriding process.
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PMID:[An experimental study of chemical debridement of full-thickness burn in rabbits by N-acetylcysteine]. 203 80

Genetically diabetic mice (db/db) were given 50 mg/kg body weight/day substance L, a nontoxic basic amino acid and compared to control diabetic mice without treatment. The oral administration of the compound was started at the age of 3 months and the animals were sacrificed at the age of 7 months. No adverse effects were observed in animals given the substance L. Total food consumption, drinking water intake and body weight were comparable between the groups. Nonenzymatic glycosylation of serum proteins and hemoglobin was not significantly different in the groups. Renal pathological lesions in the control diabetic mice showed glomerular mesangial expansion and on electron microscopy thickened glomerular basement membranes with a mean thickness of 3,204 +/- 186 A. Treated animals showed significantly less mesangial crescents and thinner glomerular basement membrane thickness of 2,520 +/- 252 A (p less than 0.01). The experimental animals showed in addition a lower mean kidney weight. Glomerular but not tubular proteinuria was reduced in the treated group. Basement membrane collagen type IV isolated from kidneys of experimental animals was more soluble in acidity and showed a lower degree of cross-linking as evaluated by SDS-polyacrylamide gel electrophoresis. We conclude that substance L is beneficial to diabetic renal changes. We suggest that this positive effect could be due to the inhibition of glucose-mediated abnormal cross-linking of collagenous structures by the interaction of substance L with reactive carbonyl residues of glycosylation adducts of collagen. Other possible mechanisms are discussed.
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PMID:The effect of substance L on glucose-mediated cross-links of collagen in the diabetic db/db mouse. 207 11

Extensive testing of collagen sponge as a vaginal contraceptive (mechanical and chemical) showed that the original expectations regarding the safety, convenience, and efficacy were not met. The collagen sponge was tested both as a cylinder and as a diaphragm and used as such or impregnated with spermicidal detergent or with zinc salt. The collagen sponge must be larger than 6 cm in diameter in order to serve as a mechanical barrier that will not be dislodged during physical activity. This creates problems with the ease of insertion and with the partners' awareness of the barrier. When the collagen sponge containing ejaculate is left in the vagina greater than 48 hours, it develops an offensive odor. The original acidity of the collagen sponge (pH 3.5, 0.1 mol/L) is soon neutralized by the large volume of alkaline vaginal secretions. In vitro studies showed that up to 10 mg of nonoxynol 9 per milliliter of growth medium did not inhibit the growth of Staphylococcus aureus. These effects, as well as the large surface area of the resilient sponge, present a potential risk for growing staphylococci within the collagen sponge. The capacity of the collagen sponge to absorb a large volume of cervical and vaginal fluid produced two symptoms that were annoying to the volunteers: an awareness of either vaginal dryness during intercourse or, conversely, saturation of the sponge from the vagina. Postcoital studies showed viable spermatozoa in the cervical mucus in 25% of the tests with the nonmedicated cylindrical sponge but in only 6% of tests with the sponge containing nonoxynol 9. The results of clinical trials conducted at four centers support the view that collagen sponge as a vaginal contraceptive barrier method is inconvenient to both partners, not effective enough to compete with present methods of vaginal contraception, and possibly might be unsafe because of the capacity to grow bacteria. Despite the negative end result of this goal-oriented research, we believe that our studies have contributed to a better understanding of vaginal physiologic features, the safety and effectiveness of spermicidal detergents, and the mechanisms of vaginal malodor. Although the acceptability study showed some advantages of the collagen sponge over the rubber diaphragm, the overall acceptability of the collagen sponge diaphragm was no better than that of the rubber diaphragm. For all these reasons, including the possible risk of an increased incidence of toxic shock syndrome, we have discontinued further testing of either type of collagen sponge as a vaginal barrier method.
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PMID:Collagen sponge as vaginal contraceptive barrier: critical summary of seven years of research. 298 68

An extracellular collagenolytic enzyme separated from a culture medium of this pathogenic yeast was found to attack undenatured predentine collagen as seen in scanning electron micrographs. After treatment with the enzyme at pH 4.0, but not by that acidity alone, dentine tubules were less easily distinguished and the collagen fibres were less well-organized.
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PMID:Degradation of human dentine collagen by an enzyme produced by the yeast Candida albicans. 307 86

The latent form of transforming growth factor-beta (TGF-beta) is a component of the extracellular matrix of bone. The active form, when locally injected in vivo, stimulates both inflammation and ectopic bone formation. The present study was undertaken to determine if TGF-beta also stimulated mineralization by isolated rat calvarial osteoblasts cultured in collagen gels. Gels were used because they should mimic in vivo conditions better than classical monolayer culture. Compared to cells in monolayers, osteoblasts cultured in collagen gels exhibited slower growth, but higher alkaline phosphatase activity and mineral deposition. Cultured cells also synthesized the osteoblast-specific marker, osteocalcin. The increase in osteocalcin in cell layers was parallel to the increase in mineral deposition. In the presence of TGF-beta, neither cell growth nor alkaline phosphatase activity increased. Instead, a small decrease occurred in both parameters when compared to untreated cultures. Accumulation of collagen, the major component of the extracellular matrix where mineralization occurs, was similar in untreated and TGF-beta 1-treated cultures. However, 8 pM TGF-beta 1 dramatically suppressed mineral deposition in both types of cultures. Despite TGF-beta 1 stimulating a fourfold increase in lactic acid, the consequent increase in culture medium acidity did not account for the inhibitory effects of TGF-beta 1 on mineralization. These results demonstrate that collagen gel culture is an improved technique over conventional monolayer culture for demonstrating differentiated osteoblast function and sensitivity to TGF-beta 1. TGF-beta 1, at a concentration that has little effect on cell growth, alkaline phosphatase activity, or collagen accumulation, is a potent inhibitor of mineralization.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Transforming growth factor-beta inhibition of mineralization by neonatal rat osteoblasts in monolayer and collagen gel culture. 779 46

The STP-C488 oncogene of herpesvirus saimiri has transforming activity independent of the rest of the viral genome. Three distinct structural regions can be predicted from the STP-C488 sequence: an acidic amino terminal domain, a collagen domain, and a hydrophobic carboxyl-terminal domain. To study the importance and functional roles of these regions, 25 different mutant forms of STP-C488 were generated. Net negative charge in the 17 amino acid amino-terminal domain was found to be important for protein structure and transformation. Increasing the net negative charge decreased electrophoretic mobility and decreasing net negative charge increased electrophoretic mobility. The three glutamic acid residues and overall acidity in this region were found to be necessary to retain potent transforming activity. Interruption of the 18 collagen-like repeats in the central region also interrupted transforming activity. The hydrophobic region at the carboxyl terminus was found to be important for membrane localization. The acidic amino-terminal domain is likely to be the catalytic or ligand binding site of STP-C488.
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PMID:Distinct functional domains of STP-C488 of herpesvirus saimiri. 794 43

The resorbable polymers polyglycolic acid (PGA) and polylactic acid (PLA) are gaining increasing importance in tissue engineering and cell transplantation. The present investigation was focused on the biocompatibility and cell retaining behavior of PGA/poly-L-lactide (PLLA) (90/10) and PLLA nonwoven structures for the in vitro development of chondrocyte-polymer constructs. The effect of the relevant monomers to chondrocytes was analyzed. Type II collagen and poly-L-lysine were compared to improve loading of PGA/PLLA and PLLA polymer nonwovens with chondrocytes. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetra-zoliumbrom ide (MTT) test was applied for quantification. At concentrations above 2 mg/mL, glycolic acid was more cytotoxic than lactic acid. As shown by pH equilibration, the cytotoxic effect is not due merely to the acidity of the alpha-hydroxy acids. Regarding the degradation products, glycolic acid, and L(+) lactic acid, nonwovens of PLLA are more biocompatible with chondrocytes than nonwovens of polyglycolide. Collagen type II and poly-L-lysine generally improved cell seeding on resorbable polymers in tissue engineering; however, their efficiency varies depending on the type of fiber structure.
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PMID:Resorbable polyesters in cartilage engineering: affinity and biocompatibility of polymer fiber structures to chondrocytes. 873 23

Mineralization of tooth dentin (the deposition of hydroxyapatite crystals in and around collagen type I fibers of the extracellular matrix) requires the involvement of several genes, among them the gene coding for the dentin matrix protein 1, DMP1. We determined the exon-intron organization of the cattle DMP1 gene and used this information to amplify by the polymerase chain reaction homologous gene fragments from the genomic DNA of two species of metatherian (marsupial) mammals and one prototherian (monotreme) species. The translated proto- and metatherian protein sequences are highly divergent from the eutherian sequences but retain the general characteristics of the DMP1 (high acidity, serine-richness, multiple glycosylation sites, and the presence of the RGD cell attachment tripeptide). They therefore appear to be functional even though, evolutionarily, teeth are in a regression phase in prototherians. It is possible, therefore, that DMP1 is also involved in other functions besides dentinogenesis. The DMP1 gene appears to evolve rapidly and apparently tolerates non-frame-shifting insertions/deletions throughout the coding sequence.
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PMID:The dentin matrix protein 1 gene of prototherian and metatherian mammals. 992 84


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