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Biomedical subjects

S W Cox

Publications and source records attributed to S W Cox.

At least 55 records · Page 3Linked to original sources
PubMed1993

Comparative histochemical and biochemical studies of mast cell tryptase in human gingiva.

Tryptase-like activity has previously been identified biochemically in gingival homogenates and gingival crevicular fluid (GCF) using substrates linked to the 7-amino-4-trifluoromethyl coumarin (AFC) leaving group. In the present study, activity was demonstrated histochemically in tissue sections with analogous 4-methoxy-2-naphthylamide (MNA) substrates. Z-Ala-Ala-Lys-MNA and D-Val-Leu-Arg-MNA were the most sensitive substrates. Comparison of staining patterns with the MNA substrates and toluidine blue indicated that enzyme activity was localized to mast cell secretory granules. Most stained cells were in the lamina propria, but a few were in the epithelium. The number of stained cells was somewhat greater in inflamed tissue from chronic periodontitis patients than in healthy tissue from controls. However, hardly any staining was seen in inflamed granulomatous tissue. Using high-salt buffer containing heparin, it was possible to extract enzyme activity from tissue sections for biochemical analysis with corresponding AFC substrates. Inhibitors gave similar results in the biochemistry and histochemistry. The inhibitor response and pH profile of the enzyme were the same as that found earlier with gingival homogenates and GCF and were again consistent with mast cell tryptase. The enzyme may have a role in the pathology of chronic periodontitis.

2-Naphthylamine↗
PubMed1992

Dipeptidyl peptidase II- and IV-like activities in gingival tissue and crevicular fluid from human periodontitis lesions.

Gingival tissue and gingival crevicular fluid were collected from patients with chronic periodontitis. Gel filtration chromatography of crude tissue extracts yielded separate fractions active against Lys-Ala-7-amino-4-trifluoromethyl-coumarylamide (AFC) at acid pH and Gly-Pro-AFC at alkaline pH. The molecular weights, pH optima and inhibitor responses of these activities were consistent with those of dipeptidyl peptidases (DPP) II and IV, respectively. When tested with the same substrates, crevicular fluid was also found to contain DPP II- and IV-like activities with very similar pH profiles and inhibitor responses to those in tissue. The close resemblance suggested that the crevicular fluid enzymes were derived mainly from inflamed gingival tissues. Slight differences in the DPP II-like activities might be explained by the additional presence in crevicular fluid of enzymes from subgingival bacteria. With use of appropriate buffers, a third substrate, Ala-Pro-AFC, gave selective detection of both DPP II- and IV-like activities in tissue and crevicular fluid. Assays with Ala-Pro-AFC had the advantage of greater sensitivity, especially with DPP II-like activity. Raised levels of this enzyme have previously been found in the gingiva of periodontitis patients and thus DPP II-like activity in crevicular fluid might prove of value in monitoring disease activity.

Chromatography, Gel↗
PubMed1992

Correlation of gingival crevicular fluid proteases with clinical and radiological measurements of periodontal attachment loss.

Probing attachment loss and radiographical measurements of bone loss were made on 20 untreated chronic periodontitis patients. At a second visit, gingival crevicular fluid was collected on filter paper strips from the deepest accessible interdental probing site of each tooth. Gingival crevicular fluid volumes were determined and the samples eluted into buffer. Protease activities in the resulting eluates were assayed with peptidyl derivatives of 7-amino-4-trifluoromethyl coumarin (AFC). Cathepsin B/L-like activity was determined with Bz-Val-Lys-Lys-Arg-AFC, elastase-like activity with MeOSuc-Ala-Ala-Pro-Val-AFC, tryptase-like activity with Z-Ala-Ala-Lys-AFC, trypsin-like activity with Z-Gly-Gly-Arg-AFC and dipeptidyl peptidase IV-like activity with Ala-Pro-AFC. Total enzyme activities and enzyme concentrations correlated positively with probing attachment loss and bone loss in linear regression analysis. This was true at both a patient level, using mean patient values, and a site level, using either individual patient or pooled patient data. All of these correlations were highly statistically significant for site comparisons. In inter- and intra-patient comparisons the proportion of significant correlations was greater for total enzyme activity than concentration. Clinical and radiological measurements of attachment loss showed generally similar levels of correlation. Total enzyme activities had good specificity and sensitivity as indicators of attachment loss in this cross-sectional study. The results support further investigation of the diagnostic potential of gingival crevicular fluid proteases in evaluation of the periodontal condition.

Adult↗
PubMed1992

Loss of synergistic response to combinations containing AZT in AZT-resistant HIV-1.

The use of combination chemotherapy for the treatment of HIV-1 infection offers promise for overcoming the problems of toxicity and development of resistance. Primary HIV-1 isolates from three patients before and after treatment with azidothymidine (AZT) were examined for sensitivity to AZT and synergistic response to three different combinations of drugs: AZT+fluorothymidine (FLT), AZT+dideoxyinosine (ddI), and FLT+ddI. All three patients initially harbored AZT-sensitive virus, but posttherapy isolates were resistant to AZT. The pretreatment, AZT-sensitive virus from each patient showed synergistic inhibition by the combinations of AZT+FLT, AZT+ddI, and FLT+ddI. In contrast, the posttreatment, AZT-resistant virus showed only addition or antagonism by the combinations containing AZT, whereas the synergistic response to the combination of FLT+ddI was preserved. Our study argues for early intervention with combination chemotherapy, since after development of resistance, AZT no longer showed synergy but addition or antagonism in combination with other drugs. After resistance to AZT has developed, combination chemotherapy not involving AZT may offer advantages over continued mono- or combination therapy involving AZT.

Antiviral Agents↗
PubMed1992

The immediate- and medium-term effects of Meswak on the composition of mixed saliva.

Chewing sticks or Meswaks are used for teeth cleaning in many parts of the world. They contain substances that may reduce caries and periodontal disease. The present study consisted of 2 parts. In a short-term experiment, volunteers chewed on an inert eliciting agent (pyrogen-free rubber) and then a piece of Meswak, each for 5 min. For the medium-term experiment, volunteers brushed with either Meswak or a conventional toothbrush 5 x a day for 2 weeks. Saliva produced immediately after chewing Meswak showed statistically significant increases in calcium and chloride, but decreases in phosphate and pH as compared with controls. In the medium-term experiment, saliva samples collected 4 h after the last use of Meswak or toothbrush showed no significant differences in any of the components examined (calcium, magnesium, chloride, phosphate, IgA, IgG, lactate dehydrogenase and aspartate transaminase). Gingival and plaque indices, however, were significantly lower after brushing with Meswak. Salivary calcium promotes mineralization of tooth enamel and chloride inhibits calculus formation. Our results thus indicate that Meswak releases substances into saliva that could improve oral health. Calcium and chloride values were similar to those of controls after 4 h and thus frequent use of Meswak may be necessary to maintain a favorable salivary environment.

Bacteria↗
PubMed1992

Cathepsin B/L-, elastase-, tryptase-, trypsin- and dipeptidyl peptidase IV-like activities in gingival crevicular fluid. A comparison of levels before and after basic periodontal treatment of chronic periodontitis patients.

20 chronic periodontitis patients were given a full periodontal examination, including measurements of probing depth, clinical attachment loss, gingival index, bleeding index and plaque index. At a second visit, gingival crevicular fluid (GCF) was collected from the deepest accessible probing site of each tooth. The patients then received scaling, root planing and other appropriate nonsurgical treatment. GCF was collected from the same sites as sampled pretreatment and clinical parameters were measured again. Cathepsin B/L-, elastase-, tryptase-, trypsin-, and dipeptidyl peptidase IV-like activities in GCF samples were determined by fluorimetric assay with peptidyl derivatives of 7-amino-4-trifluoromethyl coumarin. Following treatment, there were reductions in all clinical parameters and all protease activities. Most were statistically significant both on a patient level using average patient values and on a site level using either individual patient or pooled patient data. As in previous pre-treatment comparisons, post-treatment protease levels correlated positively and significantly with the corresponding clinical parameters at patient and site levels. The reductions and correlations were more marked for total enzyme activities than concentrations. GCF protease levels appear to reflect the clinical status of periodontal lesions and may thus be of value in monitoring disease activity.

Adult↗
PubMed1992

Cathepsin B/L-, elastase-, tryptase-, trypsin- and dipeptidyl peptidase IV-like activities in gingival crevicular fluid: correlation with clinical parameters in untreated chronic periodontitis patients.

20 untreated chronic periodontitis patients were given a full periodontal examination, including measurements of probing depth (PD), clinical attachment loss (CAL), gingival index (GI), bleeding index (BI) and plaque index (Pl.I.). At a second visit, gingival crevicular fluid (GCF) was collected on filter paper strips from the deepest accessible probing site of each tooth. GCF volumes were determined and the samples eluted into buffer. Protease activities in the resulting eluates were assayed with peptidyl derivatives of 7-amino-4-trifluoromethyl coumarin (AFC). Cathepsin B/L-like activity was determined with Bz-Val-Lys-Lys-Arg-AFC, elastase-like activity with MeOSuc-Ala-Ala-Pro-Val-AFC, tryptase-like activity with Z-Ala-Ala-Lys-AFC, trypsin-like activity with Z-Gly-Gly-Arg-AFC and dipeptidyl peptidase (DPP) IV-like activity with Ala-Pro-AFC. Total enzyme activities and enzyme concentrations both correlated positively with all clinical parameters in linear regression analysis. This was true on both a patient level, using mean patient values, and a site level, using either individual patient or pooled patient data. Most of these correlations were statistically significant, although the proportion was greater for total enzyme activity than concentration. With total activities, correlations with different enzymes and parameters generally followed the order: cathepsin B/L-greater than elastase- greater than DPP IV- greater than trypsin- greater than tryptase-like activity and PD greater than CAL greater than GI greater than BI greater than Pl.I respectively. Total enzyme activities had good diagnostic specificity and sensitivity as predictors of clinical parameters in this cross-sectional study, suggesting that GCF proteases might provide useful information on the periodontal condition.

Adult↗
PubMed1992

Cathepsin B/L-, elastase-, tryptase-, trypsin- and dipeptidyl peptidase IV-like activities in gingival crevicular fluid: a comparison of levels before and after periodontal surgery in chronic periodontitis patients.

Gingival crevicular fluid (GCF) was collected from the deepest probing site of each tooth of 10 chronic periodontitis patients prior to treatment, after scaling and hygiene treatment, and after periodontal surgery. Surgery was carried out at sites which had persistent probing depths in excess of 5 mm. The patients were given a full periodontal examination, including measurements of probing depth, gingival index, bleeding index, and plaque index before each GCF collection. Cathepsin B/L-, elastase-, tryptase-, trypsin-, and dipeptidyl peptidase IV-like activities in the GCF samples were determined by fluorimetric assay with peptidyl derivatives of 7-amino-4-trifluoromethyl coumarin. There were reductions in all clinical parameters and all protease activities after scaling and hygiene treatment and further reductions after periodontal surgery. Decreases were recorded for both total enzyme activities and concentrations. The reductions were statistically significant in inter-patient comparisons using mean patient values and also in most intra-patient comparisons using site data from individual patients. GCF protease levels appear to reflect the clinical status of periodontal lesions and may prove to be of value in monitoring disease activity.

Adult↗
PubMed1991

Cathepsin B- and L-like activities at local gingival sites of chronic periodontitis patients.

The cysteine proteinases cathepsins B and L have the potential to degrade connective tissue in chronic periodontitis and this may progress episodically at individual tooth sites. The activities of cathepsin B- and L-like proteinases in homogenised gingival tissue from control and periodontitis patients were measured biochemically using the selective peptide substrate Z-Phe-Arg-AFC and the selective cathepsin L inhibitor Z-Phe-Phe-CHN2. Each tooth site was divided, where appropriate, into gingival tissue and granulomata. These were assayed separately and the measurements related to the DNA and protein contents of the tissues. Enzyme activity in healthy control tissue was significantly lower than in diseased tissue. Enzyme activity in gingival tissue and total tissue from periodontitis patients decreased with increasing pocket depth, clinical attachment level, gingival index and bleeding index whilst cathepsin B activity in granulomata increased with increasing pocket depth and clinical attachment level but not with increasing gingival index or gingival bleeding index. Mean enzyme activity in gingival tissue was 1.6-2.8 times greater than in granulomata. Mean patient enzyme activity in diseased patients did not correlate positively with their mean pocket depth, clinical attachment level, gingival index or gingival bleeding index. These results are best explained by the probable cellular origins of the enzymes and the likely influence of their serum and tissue inhibitors during the disease process.

Adult↗
PubMed1990

A biochemical study of serine proteinase activities at local gingival tissue sites in human chronic periodontitis.

Serine proteinases have the potential to influence the degradation of connective tissue in chronic periodontitis, which may progress episodically at individual tooth sites. Elastase-, chymotrypsin- and tryptase-like proteinase activity in homogenized gingival tissue were measured using, respectively, the selective peptide substrates MeOSuc-Ala-Ala-Pro-Val-AFC. MeOSuc-Phe-Pro-Phe-AFC and Z-Ala-Arg-Arg-AFC. Each tooth site was assayed separately and divided, where appropriate, into gingival tissue and granulomata. Elastase-like activity was detected in only about half of the sites and with large variations. Chymotrypsin-like activity decreased with increasing pocket depth, clinical attachment level, gingival index and gingival bleeding index. Tryptase-like activity did not vary consistently with clinical measures. Chymotrypsin- and tryptase-like proteinase activity were much higher in gingival tissue than in granulomata. These effects are best explained by the likely influence (or lack of influence) of the endogenous serum and tissue inhibitors of serine proteinases, the different cellular origins of the enzymes, and their relative affinities for their substrates.

Adult↗
PubMed1990

A simple, combined fluorogenic and chromogenic method for the assay of proteases in gingival crevicular fluid.

Substrate impregnated paper discs were prepared using peptidyl derivatives of 7-amino-4-trifluoromethylcoumarin (AFC). After incubation with test solutions, the green, UV-induced fluorescence of AFC liberated by enzyme activity was distinguishable from the blue-violet fluorescence of the substrates. The AFC could then be coupled with p-dimethylaminocinnamaldehyde to form a colored Schiff base. Semi-quantiative assessments of disc fluorescence and color were made by comparison with AFC/substrate standards. Assays with discs impregnated with MeOSuc-Ala-Ala-Pro-Val-AFC, Z-Gly-Gly-Arg-AFC and Ala-Pro-AFC for elastase-, trypsin-, and dipeptidyl peptidase (DPP) IV-like activities respectively were evaluated using purified DPP IV and 100 eluates of crevicular fluid collected on filter paper strips from 10 gingivitis and periodontitis patients. The results showed that, within their working ranges, scores of disc fluorescence and color were reasonably accurate and reliable by comparison with enzyme activities measured in parallel quantitative fluorimetric assays with the same substrates. Using disc color, which was more sensitive than fluorescence, it was generally possible to measure all three enzyme activities in crevicular fluid samples from 5 periodontitis patients with varying degrees of gingival inflammation and pocketing. Disc color assays require no special apparatus and could be used for enzyme estimations in the clinical setting.

Amino Acid Sequence↗
PubMed1989

Identification of a tryptase-like enzyme in extracts of inflamed human gingiva by effector and gel-filtration studies.

Inflamed gingiva contain a serine proteinase which could not previously be identified on the basis of its substrate specificity and inhibitor response. Using the substrate ZAlaArgArgAFC at alkaline pH, the enzyme was shown to be extracted more efficiently in high salt buffer. Inclusion of NaCl in assays, however, caused progressive reduction of activity. There was also inhibition by CaCl2, MgCl2 and 2 mM TosLysCH2Cl but not by 2 mM TosPheCH2Cl. Heparin produced significant activation. In gel filtrations with 1.0 M NaCl, activity appeared in fractions corresponding to a molecular weight of about 135,000. These properties are all consistent with tryptase from human mast cells. The enzyme may participate in both the connective tissue destruction and the inflammatory and immunological processes of gingivitis and periodontitis.

Chromatography, Gel↗
PubMed1989

Tryptase-like activity in crevicular fluid from gingivitis and periodontitis patients.

Crevicular fluid was collected from gingivitis and periodontitis patients on filter paper strips and then eluted into buffer. The eluates hydrolyzed ZAlaArgArgAFC at alkaline pH and the effector response at pH 8.5 indicated serine proteinase activity. The results, particularly the substantial increase in activity produced by heparin, were suggestive of mast cell tryptase. They were also consistent with the properties of the tryptase-like enzyme identified in extracts of inflamed human gingiva (Cox and Eley, Arch Oral Biol, in press). Partial inhibition of crevicular fluid eluate activity by soybean trypsin inhibitor suggested the additional presence of a second trypsin-like enzyme which might be of host or bacterial origin.

Coumarins↗
PubMed1989

Detection of cathepsin B- and L-, elastase-, tryptase-, trypsin-, and dipeptidyl peptidase IV-like activities in crevicular fluid from gingivitis and periodontitis patients with peptidyl derivatives of 7-amino-4-trifluoromethyl coumarin.

Crevicular fluid samples were collected from 20 gingivitis and periodontitis patients using filter paper strips; these were then eluted into buffer. Portions of each sample were combined and the activities of this pooled eluate against different peptidyl derivatives of 7-amino-4-trifluoromethyl coumarin (AFC) were examined with respect to their pH profiles and effector responses. Ca-thepsin B- and L-like activity was detected with Bz-Val-Lys-Lys-Arg-AFC; elastase-like activity with MeOSuc-Ala-Ala-Pro-Val-AFC; tryptase-like activity with Z-Ala-Ala-Lys-AFC; trypsin-like activity with Z-Gly-Gly-Arg-AFC; and dipeptidyl peptidase (DPP) IV-like activity with Ala-Pro-AFC. The selectivity and sensitivity of these assays were improved by choice of appropriate conditions. The cathepsin B- and L-, elastase-, tryptase-, and trypsin-like activities all had properties consistent with those from host sources, whilst partial inactivation of the DPP IV-like activity by heat treatment (60 degrees C for 30 min) suggested that it may have represented a mixture of human and Bacteroides gingivalis enzymes. Individual patient eluates showed wide variations in enzyme concentrations, but generally elastase-like activity was by far the highest. The sensitivity of the assays with AFC-linked substrates was such that it should prove possible to measure all five different types of activity in crevicular fluid samples from local periodontal disease sites.

Amino Acid Sequence↗
PubMed1988

Influence of a standard laboratory diet containing nutritionally adequate levels of selenium on renal pathology from mercury released by experimental amalgam tattoos.

Twenty-four guinea pigs were subcutaneously implanted with 2 X 25 mg of powdered dental amalgam for between 1 and 24 months. Four animals served as controls. All animals were fed a standard diet containing 0.2 microgram/g selenium (Se). Mercury (Hg) was released from the implants at an average rate of 21.7 micrograms/d and 4.35-16.94 micrograms of Se were consumed daily in the diet. The renal Hg rose to a maximum of 263 micrograms/g at 11 months in implanted animals and 6.65 mg Hg was excreted over 2 yr. The renal proximal tubular cells of implanted animals contained visible Hg deposits in secondary lysosomes and within nuclei containing both Hg and Se. No other signs of obvious renal pathology were seen in implanted animals as compared with controls. It would seem likely that the low Se levels present within this standard laboratory diet were sufficient to protect against Hg toxicity.

Animals↗
PubMed1988

The prevalence of positive test results for Chlamydia trachomatis by direct smear for fluorescent antibodies in a south Texas family planning population.

Chlamydia trachomatis is a major human genital pathogen implicated as a leading cause of involuntary infertility in women. To assess the prevalence of results positive for C trachomatis by a direct immunofluorescent test in a family planning population, mass screening of all patients attending five urban family planning clinics was conducted for a two-month period. The objectives of this study were to assess the prevalence of positive C trachomatis test results in this population and to evaluate the commonly accepted demographic/behavioral risk factors reported in previous studies. A total of 2,761 subjects were tested using the MicroTrak collection kit. The subjects ranged in age from 12 to 69 years. The overall rate of positive test results was 10.5%. Significant associations between C trachomatis test results and the following variables were observed: race/ethnicity, age, marital status, existence of multiple partners and positive gonorrhea tests. Chlamydial infection was not significantly associated with income, pregnancy, current contraceptive method or age at first intercourse. While the results of the study indicated both agreement and disagreement with other clinical investigations, the fact that 10.5% of a largely asymptomatic population exhibited chlamydial infection has major implications for the management of women's reproductive health care.

Adult↗