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Biomedical subjects

J M Rhodes

Publications and source records attributed to J M Rhodes.

18 recordsLinked to original sources
PubMed1992

A novel mucin sulphatase from human faeces: its identification, purification and characterization.

1. Colonic mucus is heavily sulphated and it is likely that this contributes considerably to its resistance to degradation by bacterial enzymes. The presence of a mucin-desulphating enzyme in faeces could therefore be very important in determining the rate of degradation of secreted mucus and hence the level of protection of the mucosa. 2. A novel assay for mucin sulphatase has been developed using biologically labelled human colonic [35S]sulphomucin as a substrate and a mucin sulphatase has been purified from faeces by sequential high-performance gel filtration and ion-exchange chromatography. 3. The mucin sulphatase has been shown to have a pH optimum of 4.5 and activity over the pH range 3-7. It has a pI of 4.0 and is inhibited by inorganic sulphate and phosphate. The purified enzyme preparation gave a single band on electrophoresis with a molecular mass of 15,000 Da. It has a Km of 41.9 mmol/l and a Vmax. of 1.17 katal/kg for glucose 6-sulphate. The enzyme was also shown to enhance fivefold the deglycosylation of [3H]glucosamine-labelled mucin by a faecal mucin glycosidase preparation. 4. Two bacteroides spp. isolated from normal human faeces, Bacteroides fragilis and B. thetaiotaomicron, were found to be producers of mucin-desulphating enzymes. 5. Mucin sulphatase is likely to be critical in determining the rate of enzymic degradation of secreted colonic mucin.

Bacteroides fragilis↗
PubMed1992

Sulphation of colonic and rectal mucin in inflammatory bowel disease: reduced sulphation of rectal mucus in ulcerative colitis.

1. Normal colonic mucin is heavily sulphated and this increases its resistance to degradation by bacterial enzymes. Any defect in mucus sulphation could therefore be important in the pathogenesis of ulcerative colitis. 2. Rectal biopsies taken at colonoscopy from patients with ulcerative colitis (n = 9), patients with Crohn's disease (n = 6) and control subjects (n = 16) were cultured for 24 h in the presence of N-[3H]acetylglucosamine and [35S]sulphate. Mucin was then extracted and purified, and the ratio of [35S]sulphate to N-[3H]acetylglucosamine incorporated into pure mucin was assessed. 3. The ratio of [35S]sulphate to N-[3H]acetylglucosamine incorporated into mucin was significantly reduced in rectal biopsies taken from patients with ulcerative colitis (0.463, 0.305-0.703, geometric mean and 95% confidence intervals) compared with control subjects (0.857, 0.959-1.111, P < 0.01). In patients with Crohn's disease the reduction in this ratio (0.559, 0.378-0.829) did not quite reach statistical significance (P = 0.06). There was no difference between the ratio of [35S]sulphate to N-[3H]acetylglucosamine incorporated into mucin in Crohn's disease and that in ulcerative colitis (P = 0.26). 4. In control subjects the ratio of [35S]sulphate to N-[3H]acetylglucosamine incorporated into mucin was higher in the rectal biopsies (0.882, 0.618-1.022) than in their paired proximal colonic biopsies (0.602, 0.421-0.861; P < 0.01), but this regional variation was not observed in either ulcerative colitis (rectum: 0.450, 0.262-0.773; right colon: 0.470, 0.321-0.690, P = 0.3) or Crohn's disease (rectum: 0.459, 0.260-0.815; right colon: 0.492, 0.260-0.929, P = 0.8).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Use of an ammonia electrode for rapid quantification of Helicobacter pylori urease: its use in the endoscopy room and in the assessment of urease inhibition by bismuth subsalicylate.

The use of an ammonia electrode to quantify ammonia liberated by urease from Helicobacter pylori was assessed in an in vitro study. It was found to be highly sensitive (down to 0.7 ppm NH3) and highly reproducible (coefficient of variation 6.0%). Inhibition of urease by bismuth subsalicylate was evaluated as urease testing is often used to assess clearance of H. pylori in patients treated with bismuth. Concentrations of bismuth subsalicylate up to 5 mg/ml had no inhibitory effect but bismuth subsalicylate at 50 mg/ml resulted in 21% inhibition of the urease activity of an ultrasonicated H. pylori suspension. As a preliminary study, the ammonia electrode was assessed in the endoscopy room in comparison with conventional techniques for H. pylori diagnosis. Antral biopsies from 39 patients attending for routine diagnostic endoscopy were subjected to culture, histology, detection of urease activity with a commercially available slide test (CLO) and with the ammonia electrode to detect ammonia liberated from samples placed in urea solution. 21 patients were positive after 1 h with the ammonia electrode, compared to only 17 with the commercially available slide test. 20 were positive on histology and 19 by culture. All samples positive with the ammonia electrode were either positive by culture or by histology. The ammonia electrode offers a quick, sensitive, quantitative and cheap method for the detection and quantification of H. pylori.

Ammonia↗
PubMed1979

Screening for pancreatic disease: A comparison of grey-scale ultrasonography and isotope scanning.

The efficiency of ultrasound in the diagnosis of pancreatic disease was compared prospectively with that of selenomethionine isotope scanning in 46 patients presenting with abdominal pain or weight-loss or with jaundice. Of 14 patients who later proved to have pancreatic carcinoma, all had an abnormal isotope scan and 13 had an abnormal ultrasound scan. Of 10 patients with chronic pancreatitis, all had an abnormal isotope scan and 9 had an abnormal ultrasound scan. The small advantage of selenomethionine was, however, offset by a higher false-positive rate: of 22 patients who proved not to have pancreatic disease, 13 had abnormal isotope scans compared with only 3 with ultrasound. Review of earlier experience with the two techniques yielded similar results: in pancreatic carcinoma and chronic pancreatitis, isotope scanning gave slightly fewer false-negative results than ultrasound but many more false-positives. Because of its lower false-positive rate, because it avoids ionising radiation, and because it can usually distinguish carcinoma from pancreatitis, ultrasound is the procedure of choice for initial investigation of patients with suspected pancreatic disease.

Chronic Disease↗
PubMed1979

Correlation between in vivo and in vitro functional tests for activated macrophages.

Mice undergoing graft-versus-host reaction, skin grafting, and inoculation with tumor cells were tested for nonspecific resistance by intravenous challenge with Listeria monocytogenes. Peritoneal exudate macrophages from mice treated in a similar manner were tested in vitro for increased degradation of [1-14C]glucose, ability to degrade antigen/antibody complexes, ability to inhibit intracellular growth of listeria, and staining for beta-galactosidase. There was good correlation between in vivo resistance towards L. monocytogenes and in vitro inhibition of intracellular growth. There was also good correlation between increase in beta-galactosidase and in vivo resistance in mice undergoing a graft-versus-host-reaction.

Animals↗
PubMed1979

The lactulose hydrogen breath test as a diagnostic test for small-bowel bacterial overgrowth.

The lactulose hydrogen breath test has been evaluated as a diagnostic test for small-bowel bacterial overgrowth using the 14C-glycocholate breath test for comparison. Twenty-seven patients with suspected bacterial overgrowth and 37 control patients were studied. The lactulose test was positive in 8 out of 9 patients with Subsequently proven bacterial overgrowth, all of whom had positive 14C-glycocholate tests. However, 6 patients with ileal disease or resection had positive 14C-glycocholate tests but negative lactulose tests. subsequent bacteriological study of duodenal juice from these patients was negative. Negative results were obtained by both tests in the remaining 12 patients, none of whom were subsequently shown to have bacterial overgrowth. All 37 control subjects had negative lactulose tests. The lactulose breath test is a simple and promising diagnostic test for the detection of small-bowel bacterial overgrowth and, unlike the 14C-glycocholate test, has the advantage of being able to distinguish bacterial overgrowth from ileal disease.

Breath Tests↗
PubMed1978

Macrophage activation by lymphokines and after direct contact with sensitized lymphocytes: histocompatibility requirements and the effect of inhibitors.

A comparison was made between two procedures which give rise to in vitro activation of normal mouse peritoneal macrophages: (1) normal macrophages were incubated for 22 h with sensitized lymphocytes and antigen (assay A), and (2) normal macrophages were incubated for 70 h with supernatants from sensitized lymphocytes and antigen (assay B). The activation of macrophages was measured as an increase in 1-14 C glucose oxidation. Combinations of lymphocytes and macrophages is probably necessary in assay A.s from different mouse strains demonstrated that activation of macrophages in assay A, but not in assay B, required cells which were derived from strains of mice sharing identical H-2 antigens. Treatment of lymphocytes with mitomycin C blocked the activation of macrophages in both assays. Addition of alpha-L-fucose (0.1 M) during the incubation period blocked the activation of macrophages in assay B, but not in assay A. It is concluded that there is a qualitative difference between the two methods for activating macrophages and that direct contact between lymphocytes and macrophages is probably necessary in assay A.

Animals↗
PubMed1977

In vitro studies on normal, stimulated and immunologically activated mouse macrophages. I. Oxidation of 1-14C glucose by macrophages in monolayer cultures.

Oxidation of 1-14C glucose of BCG/listeria activated, proteose-peptone stimulated and typhoid-parathypoid vaccine (T.A.B.) stimulated peritoneal and spleen macrophages from C3H, CBA and C57Bl mice was determined at various times after treatment. The study showed no major differences between the oxidation of stimulated and activated macrophages, but a variation was seen in C3H mice in the kinetics of glucose oxidation of BCG/listeria activated and proteose-peptone stimulated peritoneal macrophages. It was also observed, in these mice, that the response appeared and disappeared earlier in the spleen than in the peritoneal macrophages.

Animals↗
PubMed1977

In vitro studies on normal, stimulated and immunologically activated mouse macrophages. II. Degradation of radioactive antigen/antibody complexes.

Radioactive antigen/antibody complexes are degraded to a greater extent by PE macrophages from C3H, CBA and C57Bl mice injected intraperitoneally with proteose-peptone (stimulated macrophages) and T.A.B. vaccine than by PE macrophages from normal mice and mice immunized with BCG (activated macrophages). On the other hand, spleen macrophages from mice immunized with BCG had a greater digestive capacity than macrophages from mice injected with proteose-peptone or T.A.B. vaccine or from normal mice. Thus, activated macrophages are capable of degrading antigen/antibody complexes, provided that the cells are harvested from one of the foci of BCG infection.

Animals↗
PubMed1977

In vitro studies on normal, stimulated and immunologically activated mouse macrophages. III. Intracellular multiplication of Listeria monocytogenes.

The intracellular generation time of Listeria monocytogenes is increased in monolayers of PE macrophages from mice immunized with BCG, listeria and T.A.B. vaccine as compared with monolayers of PE macrophages from normal mice stimulated intraperitoneally with proteosepeptone. Thus non-specifically stimulated and immunologically activated macrophages, although sharing several other characteristics, differ in their capacity to control intracellular bacterial infection.

Animals↗
PubMed1975

The effect of cyclophosphamide, methotrexate and X-irradiation on the ultrastructure and endocytic capacity of murine peritoneal macrophages.

100 mg/kg cyclophosphamide given subcutaneously daily for 5 days and whole-body X-irradiation (500 r) had an appreciable effect on the phagocytosis of E. coli by mouse peritoneal macrophages. Less bacteria were ingested by cells from the treated mice as compared with control cells. In contrast, whole-body X-irradiation had a stimulatory effect on pinocytosis as compared with cells from cyclophosphamide treated mice or control mice. Morphological changes in the cells from animals treated with cyclophosphamide or X-rays were evident. The cells were larger than normal macrophages and contained large amounts of lipid and phagolysosomes and had more vacuoles as compared with control cells. Many giant cells were present in the treated mice. Treatment of mice with methotrexate for 5 days, although affecting the cells morphologically in that they were larger than normal cells and had many vacuoles did not appear to have any effect on either phagocytosis or pinocytosis. Cells from methotrexate treated animals did not contain the large quantities of lipid seen in cells from the cyclophosphamide treated and X-irradiated mice.

Animals↗
PubMed1975

The effect of various immunosuppressive agents on mouse peritoneal macrophages and on the in vitro phagocytosis of Escherichia coli O4:K3:H5 and degradation of 125I-labelled HSA-antibody complexes by these cells.

Large doses of hydrocortisone, cyclophosphamide, and methotrexate injected subcutaneously, and whole-body irradiation (500 rads) caused a reduction in the number of peritoneal cells (PE cells) obtained after intraperitoneal injection of the treated mice with proteose-peptone. The same dose of cyclophosphamide and irradiation induced morphological changes in PE macrophages. There were more giant cells in the peritoneal exudates from treated mice as compared to control mice. 'Pharmacological' and larger doses of hydrocortisone, methotrexate and azathioprine or anti-lymphocyte globulin had no effect on the in vitro phagocytic capacity of proteose-peptone-stimulated mouse PE macrophages. This also applied to doses of up to 50 mg/kg of cyclophosphamide. In contrast, whole-body irradiation (500 rad) and 100 mg/kg of cyclophosphamide decreased the phagocytic capacity of mouse macrophages in vitro and reduced the ability of PE cells to degrade 125I-labelled HSA-antibody complexes in vitro. The greatest effect was noted 4-5 days after whole-body irradiation or four to five subcutaneous injections of cyclophosphamide.

Animals↗