Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:6.3.4.6 (urease)
7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Helicobacter pylori (H.p.) is a microorganism involved in peptic ulcer disease. To clarify the role of human dental plaque as a reservoir of H.p. and to compare different methods of investigation the authors studied 20 patients, 17 males main age 56 +/- 12 and 3 females 52 +/- 7, gastro-duodenal H.p. positive. The trial was carried out by cultural, biochemical and microscopical plaque analysis. Cultural and microscopical method were H.p. positive in 80% patients, urease in 100%, alkaline phosphatase in 80%, gamma glutamyltransferase in 70%, nitrate in 70%. To minimize the possibility of false results in H.p. plaque analysis it is necessary to use the three methods simultaneously. Further trials both on human plaque and on food and beverages will be useful to clarify the role of H.p. in human pathology.
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PMID:Comparison of three different methods for evaluation of Helicobacter pylori (H.P.) in human dental plaque. 130 23

Coxsackievirus B3 (CVB3) infections induce myocardial inflammation which is presumably mediated by autoimmune mechanisms in the experimental murine model. Naturally occurring antibodies that also bind to myocytes have been identified that can either abrogate or enhance cardiac injury by modulating the immune response. Monoclonal antibodies derived from CVB3-infected mice were immobilized to plastic and overlaid with spleen cells obtained from mice infected with 5 x 10(4) plaque forming units of CVB3 0 to 8 days earlier. Controls consisted of either myocytes or virus adsorption monolayers. After incubation, non-adherent lymphocytes were removed, the adherent cells were recovered and cultured on either virus or myocytes for 48 h at 37 degrees C. The lymphocytes were removed and any antibody binding to the virus or myocytes was detected using goat anti-mouse IgG and IgM in a urease enzyme-linked immunoadsorption assay (ELISA). The original unfractionated spleen cell population added directly to the ELISA wells showed reactivity to both virus and myocytes. Cells adsorbed to myocytes made primarily myocyte-reactive antibody and cells adsorbed to virus made primarily virus-reactive antibody. Cells adsorbed to the heart-reactive mAB (10A1) made primarily virus-specific antibody suggesting this autoantibody might be an anti-idiotype of the virus-reactive response.
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PMID:Naturally occurring anti-idiotypic antibodies--mechanisms for autoimmunity and immunoregulation? 165 45

Our purpose was to determine the urea concentration in minor mucous gland (MMG) secretions and the pH at proximal and distal aspects of the lower surface of artificial plaque in vitro during infusion of urea solutions over the surface, at different film velocities. Saliva is present in the mouth as a slowly moving film (ca. 0.1 mm thick) with an estimated velocity in the range of 0.8-8.0 mm/min. At low velocities, due to the accumulation of bacterial products, a progressive increase in their concentration may occur in both the plaque and the overlying salivary film at the distal edge (where the film leaves the plaque). S. vestibularis, an oral micro-organism possessing ureolytic activity, was combined with 1% agarose, to give a urease Vmax similar to that of natural plaque. The artificial plaque was in the chamber (6.0 x 6.0 square and 0.5 or 1.5 mm deep) of a diffusion apparatus, and a urea-containing artificial saliva (3.3 or 13.2 mmol/l) was infused over the surface, as a film 0.1 mm deep, at velocities of 0.8, 8.2 and 86.2 mm/min. At the lower (physiologically normal) urea concentration and the two lower film velocities, most urea appeared to be metabolized at the proximal end of the plaque, which developed a higher pH. At the higher urea concentration, and a film velocity of 8 mm/min, a higher pH was found at the distal end. This was probably due to the combination of greater urea availability and a reduced rate of ammonia loss distally. At a film velocity of 86.2 mm/min, proximal/distal pH gradients did not develop.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Urea concentration in minor mucous gland secretions and the effect of salivary film velocity on urea metabolism by Streptococcus vestibularis in an artificial plaque. 183 51

A plaque growth chamber was developed for long-term growth of five separate plaques from the same plaque or saliva sample under identical conditions of temperature and gas phase. Reagent addition and growth conditions for each plaque could be independently controlled, and each was accessible for sequential sampling and electrode insertion. Plaques were cultured for over six weeks on pellicle-coated Lux (TM) 25-mm diameter cover-slips at 35 degrees C under 5% CO2 in N2, and supplied with a medium containing 0.25% mucin (BMM) at 3.6 mL/h, and with periodic 5% sucrose. Electron microscopy and flora analysis of microcosm plaques showed that they had close similarities to reported characteristics of natural dental plaques. Diverse motile bacteria were present. Sucrose-induced Stephan pH curves and urea-induced pH rises were also similar to those reported for natural plaques. Changes in plaque urease, calcium, phosphate concentrations, and the flora were followed over five weeks in a plaque supplied with BMM containing additional 2.5 mmol/L calcium and 7.5 mmol/L phosphate. Despite this high environmental calcium phosphate concentration, there was no continuing increase in calcium levels, although plaque phosphate doubled. Urease levels fluctuated. Changes in the cultivable flora were minor. A urea-containing calcium phosphate/mono-fluorophosphate pH 5 solution, applied for six min every two h for seven days, increased plaque calcium, phosphate, and fluoride to high levels. Thus, plaques grown over several weeks in the multi-station artificial mouth exhibited metabolic and pH behavior typical of natural plaques, could be analyzed during development, and the system allowed manipulation of environmental variables important in plaque pH control and calcification.
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PMID:A multi-station dental plaque microcosm (artificial mouth) for the study of plaque growth, metabolism, pH, and mineralization. 196 Feb 50

The form, location, and distribution of fluorhydroxyapatite deposited in dental plaque by a urease-mediated mineral enrichment process have been studied by transmission electron microscopy. Artificial plaque was formed in terylene gauze in the mouth of one subject and immersed for five min four times per day in a mineral-enriching solution. Contralateral control plaque remained untreated. The effect on natural plaque was studied in two subjects who withheld oral hygiene for four days and mouthrinsed with this solution for two min four times per day during the last two days. Mineral deposits were seen in all plaque samples exposed to the test solution. None was detected in any control sample. The deposits were scattered in the interbacterial matrix as needle-shaped crystals, the size and shape of apatite, together with amorphous material. The crystals appeared larger and more perfect, and the amorphous material less conspicuous, with longer in vivo rinsing periods. Platelet-shaped crystals of octacalcium phosphate were never seen. Mineral was also seen within the remnants of dead bacterial cells and within degenerating epithelial cells. Crystals were never seen within intact bacterial cells, as in calculus formation. The presence of a single crystal type and the relative absence of densely-mineralized foci are other differences between this mineral-enrichment process and supra-gingival calculus formation. A longer-term study is necessary to determine whether the solution promotes calculus by providing nucleation seeds.
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PMID:Therapeutic mineral enrichment of dental plaque visualized by transmission electron microscopy. 199 74

Experimental conditions were established for the extraction, electrophoresis and detection of urease isoenzymes from Streptococcus salivarius. Thiol concentrations were critical and ureases from different strains varied in ease of dissociation. A characteristic pattern was obtained for 30 ureolytic S. salivarius strains isolated from; saliva (6), dental plaque (12), artificial dental plaque (6) and non-oral sources (6), and also for a ureolytic Streptococcus bovis from artificial plaque. One non-oral S. salivarius strain had ureases with slightly slower mobility. The electrophoretic pattern and mobility of ureases extracted from human mixed salivary bacteria were identical to those from S. salivarius except for an additional set of urease bands from unknown species of bacteria. There were no ureases from saliva matching those from Staphylococcus epidermidis--a contributor to ureolysis in artificial plaque. We conclude that there is considerable biochemical homogeneity among S. salivarius ureases and possibly other ureolytic streptococci. In saliva, urea is metabolized mainly by streptococcal ureases.
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PMID:Electrophoretic analysis of ureases in Streptococcus salivarius and in saliva. 264 Mar 15

In November 1985, a 5-year-old Chinese girl presented to the Dermatological Department of Chang Gung Memorial Hospital, Taipei, having scaly erythematous plaque with mild itching on her right upper eyelid. Skin biopsy and fungal cultures were performed after failure of initial topical steroid therapy. The histopathology revealed many acute and chronic inflammatory cells infiltrating the dermis and H & E stain revealed some foamy vacuolated spores; P.A.S. and Gomori's methenamine stain also showed many spores and sporangia containing endospores. Lactophenol cotton blue and methylene blue wet mount preparations were made from the colony growing on Sabouraud's agar. Microscopically, these showed many round or oval spores and endospore-containing sporangia, corresponding with the histopathology. This microorganism grew as a milky white yeast-like colony on Sabouraud's dextrose agar, blood agar, EMB, Tween 80 cornmeal agar, chocolate agar, MacConkey agar and brain heart infusion with sheep RBC agar. On Pagano-Levin medium, the colony became deep red in color and in the thioglycollate broth tube culture, it was suspended on the upper layer as a whitish ring-form of granules. The microorganism showed no urease activity. In the assimilation tests, there were positive reactions to glucose, galactose, trehalose, fructose, mannose and glycerol, and negative reactions to maltose, xylose, raffinose, sucrose, lactose, cellabiose, n-propanol, etc. The electronmicroscopic examination of the colony revealed sporangium containing spores and characteristic dense body and plastids in the spores.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Cutaneous protothecosis: first case in Taiwan]. 280 69

The origin of ureolytic activity in artificial-mouth plaques was established by assessing the contribution to plaque ureolytic activity of the isolated bacteria. To overcome losses of ureolytic activity caused by the unstable presence of urease in oral bacteria, ureolytic bacteria were isolated from an exceptionally active plaque (1 mumol NH3/min per mg protein) in which 63 per cent of the flora was ureolytic. After their ability to metabolize urea was stabilized, 13 ureolytic bacteria remained: seven strains of Streptococcus salivarius, one Streptococcus bovis, two Staphylococcus epidermidis and three Staphylococcus haemolyticus. Their urease activity, measured after growth into stationary phase, was reproducible and strain specific with a 20-fold range within each genus. The mean ureolytic activity of each species, when weighted by its calculated incidence in the original plaque, accounted for 40 per cent of the total plaque ureolytic activity. However, these values for urease levels were only a small fraction of the bacterial ureolytic potential. Urease per mg cell protein measured during the growth cycle of a selected Strep. salivarius, and Staph. epidermidis, varied 10-fold, and reached much higher activities (i.e. 6-8 mumol NH3/min per mg of cell protein) than under the growth conditions that were used to assess the contribution of these species to total plaque ureolysis. Thus urea metabolism in artificial plaque was due mainly to Strep. salivarius, with a small contribution from Staph. epidermidis. The presence of further unidentified species of ureolytic oral bacteria need not be invoked.
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PMID:The bacteria responsible for ureolysis in artificial dental plaque. 307 50

Certain dental plaques, removed from sites of gingival and periodontal pathology in mentally retarded, institutionalized individuals, when incubated in phosphate buffer with Achilles tendon collagen, gave rise to an increase in ninhydrin-positive material. These plaques, while showing great variability, released significantly more ninhydrin-positive material per milligram of plaque (wet weight) than did either the endogenous or heat-treated controls. Certain plaques could also break down soluble, tritiated, labeled collagen isolated from the calvaria of chicken embryos. Bacteroides melaninogenicus and Clostridia histolyticum were found in plaques by either fluorescent antibody or cultural methods. C. histolyticum, when detected, accounted for about 0.01 to 0.1% of the bacteria in plaque. A conspicuous isolate from some plaques was a Bacillus species which rapidly liquefied gelatin. Cell-free supernatants of this organism were able to degrade about 50 to 70% of the soluble collagen when incubated at 36 C. C. histolyticum ATCC 8034 caused an 80% degradation of the collagen under the same conditions of incubation. The Bacillus strains were facultative, could ferment glucose, reduced nitrate to nitrite, and were catalase, indole, and urease negative. The limited taxonomic information for the isolates is compatible with the description given for Bacillus cereus.
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PMID:Collagenolytic activity of dental plaque associated with periodontal pathology. 436 Dec 94

Helicobacter pylori causes human type B gastritis and is involved in the etiology of peptic ulcer disease. The routes of transmission of H. pylori are still unclear. The microorganism may be transmitted orally, since H. pylori has been detected in dental plaques. To confirm the hypothesis that dental plaques are a reservoir of H. pylori, 100 dental plaque specimens from 55 dental surgery patients were incubated on one nonselective and up to four selective agar media for the detection of H. pylori. In addition, urease activity of the plaque material was tested, and the gingival status of the patients was assessed. H. pylori was not cultivated from any of the specimens investigated. Plaque material from 12 patients with moderate and severe gingivitis showed urease activity. The results do not confirm the hypothesis that dental plaques are a relevant reservoir of viable H. pylori cells. However, non-cultivatable forms of H. pylori may survive in dental plaques. Urea cleaving activity of dental plaque may be a marker of gingival inflammation.
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PMID:No cultural detection of Helicobacter pylori in dental plaque. 780 25


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