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Biomedical subjects

G Steinbach

Publications and source records attributed to G Steinbach.

At least 73 records · Page 4Linked to original sources
PubMed1996

Calcium supplementation modifies the relative amounts of bile acids in bile and affects key aspects of human colon physiology.

Use of calcium supplements has increased dramatically in recent years yet little is known about the effect of calcium supplementation on colon physiology. We supplemented 22 individuals with a history of resected adenocarcinoma of the colon, but currently free of cancer, with 2000 or 3000 mg calcium for 16 wk. The effects of supplementation on duodenal bile acids and important fecal characteristics including total fecal output, wet and dry weight, pH, bile acids (in solids and in fecal water), and concentrations and total excretion of calcium, magnesium, phosphates (organic and inorganic), unesterified fatty acids and total fat were determined. Calcium supplementation significantly decreased the proportion of water in the stool (P = 0.03), doubled fecal excretion of calcium (P = 0.006), and increased excretion of organic phosphate (P = 0.035) but not magnesium. Calcium supplementation significantly decreased the proportion of chenodeoxycholic acid in bile (P = 0.007) and decreased the ratio of lithocholate to deoxycholate in feces (P = 0.06). The concentration of primary bile acids in fecal water decreased after 16 wk Ca supplementation. Together with other reports of a "healthier" bile acid profile with respect to colon cancer when changes such as those observed in this study were achieved, these results suggest a protective effect of calcium supplementation against this disease.

Adenocarcinoma↗
PubMed1996

Calcium carbonate treatment of diarrhoea in intestinal bypass patients.

OBJECTIVE: To study the effect of supplemental calcium carbonate on faecal water, calcium, bile acid and lipid concentration and output in intestinal bypass subjects with diarrhoea. DESIGN: Prospective, single-arm treatment trial of oral calcium carbonate, 2400 or 3600 mg Ca2+ per day, given for 12 weeks. METHODS: Faecal constituents were determined in wet or lyophilized stool of 24-h collections at baseline and at 12 weeks of study. Calcium was measured by absorption spectrophotometry. Bile acids, long-chain fatty acids and short-chain fatty acids were analysed by gas chromatography. RESULTS: In 15 subjects, calcium supplementation reduced bowel frequency by a mean of 49%, faecal wet weight by a mean of 50% (1292 to 646 g per day), and dry weight by a mean of 36%, P < 0.001. Faecal water concentration was reduced from 76.4 +/- 1% to 70.2 +/- 2%, P < 0.01. Faecal water concentration was inversely correlated with dry faecal calcium concentration (r = -0.75 P = 0.00001). CONCLUSION: Calcium reduces the diarrhoea of intestinal bypass patients. It is suggested that the constipating effect of calcium may be related to reduction in faecal water.

Adult↗
PubMed1996

[Immunization with potential Salmonella enteritidis mutants-- 2. Investigations on the attenuation and immunogenicity for mice and young hens].

Adenine-amino acid auxotrophic Salmonella Enteritidis double mutants were investigated for their in vivo stability, attenuation und immunogenicity using NMRI-mice and SPF-chicks. All mutants used were stable in vivo and attenuated. Two mutants were selected for immunization experiments in chickens according to their protective ability after a single intraperitoneal immunization in NMRI-mice using a homologous and heterologous challenge. After two oral immunizations and homologous oral challenge with the S. Enteritidis wild type strain 6403Nalr, a significant difference (p < 0.01) was demonstrated between the mean caecal bacterial counts of immunized and control chicks. Examination of liver samples revealed a significantly lower degree of colonization of internal organs (p < 0.01) in immunized birds. There was no evidence of cross protection against S. Typhimurium using S. Enteritidis mutants.

Animals↗
PubMed1995

[Is radical prostatectomy a suitable model for determination of PSA half-life?].

A review of the literature relating to PSA half-life reveals great variability in absolute values and pharmacokinetic models. A critical view is needed, however, since some authors suggest that the PSA half-life has implications for diagnosis and prognosis after radical prostatectomy. The aim of our study, therefore, was to characterize the value of PSA half-life determination after radical prostatectomy. Serial serum PSA detections were performed in 16 patients with localized prostatic cancer who had undergone radical prostatectomy. Serum PSA was detected on days 0, 1, 2, 3, 6, 9, 12, 15, 18, after radical prostatectomy. In all patients elimination of PSA from serum followed a biphasic logarithmic decay pattern indicating a two-compartment model of first order elimination kinetics (t1 = 1.01 +/- 0.06 days, t2 = 3.42 +/- 0.23 days; P < 0.00001). In this two-compartment model 56.3 +/- 4.8% of the preoperative PSA serum concentration was cleared by the first compartment. To find a biological correlative for the first compartment a mathematical model was developed to approximate the effect of operative blood and plasma loss on PSA serum concentration. In this model changes of hematocrit were used to estimate blood and plasma loss. These calculations showed that 50.12 +/- 3.04% of the preoperative PSA serum concentration was excreted by operative blood loss. This value was not significantly different from the clearance rate calculated for the first compartment. It is, therefore, concluded that the determination of PSA half-life after radical prostatectomy without correction of the operation-related PSA loss is only of limited value.

Adult↗
PubMed1995

[The specificity of antibodies reacting with Salmonella antigens in ELISA].

Among cattle sera from herds without a history of salmonellosis and without vaccination against salmonellas, we sometimes found samples which reacted positively in the ELISA with salmonella antigen. Contrary to antibodies caused by a proved salmonella infection, these antibodies could be eliminated by a whole-cell lysate of E. coli. In the colostra of cows which had received a salmonella live vaccine orally in the first days of life but were raised and kept without known exposition to salmonellas, we also found antibodies which reacted in the salmonella ELISA. They could not be eliminated by E. coli lysate.

Animals↗
PubMed1994

Effect of caloric restriction on colonic proliferation in obese persons: implications for colon cancer prevention.

Dietary intervention to prevent colon cancer is a major health issue. At present it is not clear which dietary factors modify colon cancer risk. Caloric restriction reduces the incidence of many spontaneous and carcinogen-induced tumors in rodents, but its role in human carcinogenesis is unknown. The relationships of body mass index (BMI), body composition, and resting metabolic rate (RMR) to colon cancer risk are also undefined. In this study involving obese persons, we measured the effect of reducing caloric intake on rectal cell proliferation, a biomarker in colon carcinogenesis, and studied the relation of BMI, body composition, and RMR to rectal cell proliferation. Colonic cell proliferation was measured in rectal biopsies from persons weighing more than 130% of ideal body weight. Follow-up biopsies were performed in patients who enrolled in and completed a 16-week behavior modification weight-reduction program in which caloric intake was reduced. Baseline measurements included body composition by total body electrical conductance, RMR, and BMI. Rectal biopsies were processed for autoradiography following incubation with [3H]thymidine. Epithelial proliferation measurements were evaluable in 35 persons at baseline and in 8 persons before and after caloric restriction. Before caloric restriction, mean (+/- SD) BMI was 38 +/- 4 kg/m2 and percentage of body fat 41 +/- 2%. Subjects reduced their caloric intake by a mean of 34 +/- 4% and their weight by 8.6 +/- 1%. Caloric restriction resulted in a 39% reduction in whole-crypt labeling index (P < 0.001) and a 57% reduction in upper crypt labeling index (P < 0.05) without reduction in crypt depth. Labeling index was unrelated to BMI, RMR, or body composition. We conclude that caloric restriction reduced rectal cell proliferation measurements--intermediate biomarkers related to colon carcinogenesis. BMI, RMR, and body composition were unrelated to colonic proliferation. Caloric restriction may have a role in colon cancer prevention.

Adult↗
PubMed1994

Calcium reduces the increased fecal 1,2-sn-diacylglycerol content in intestinal bypass patients: a possible mechanism for altering colonic hyperproliferation.

Diacylglycerol (DAG) is a second messenger for protein kinase C, an enzyme with a key role in cellular signal transduction and growth control. In previous studies, it was demonstrated that DAG is produced by intestinal microflora. Bacterial DAG production is increased by bile acids and phospholipids, both of which may be precipitated by calcium. We have demonstrated that fecal total lipids, bile acids, and rectal epithelial proliferation are increased in intestinal bypass (IB) patients. Calcium was shown to alter fecal lipid composition and to reduce cell proliferation. In the present study, fecal DAG content and 14C-labeled DAG, 14C-phosphatidylcholine, and 14C-phosphatidylinositol metabolism were measured in 24-h stool collections in 15 stable IB patients before and after 3-month therapy with oral elemental calcium, 2.4 or 3.6 g/day. Fecal DAG concentration and output in IB patients were > 25- and > 200-fold greater than in normal controls. Oral calcium markedly reduced fecal DAG concentration and output and increased DAG, phosphatidylcholine, and phosphatidylinositol metabolism without enhancing DAG production. We conclude that fecal DAG content is markedly elevated post-IB and that calcium supplementation in these patients reduces fecal DAG and accelerates bacterial metabolism of DAG and its precursors. In separate studies, we have found that calcium supplementation also decreases rectal hyperproliferation in IB patients. Taken together, these findings suggest that a high luminal level of DAG enhances colonic cell proliferation and that calcium reduces cell proliferation in part by decreasing the level of DAG.

Calcium↗
PubMed1994

Effect of calcium supplementation on rectal epithelial hyperproliferation in intestinal bypass subjects.

BACKGROUND/AIMS: Fatty acids and bile acids are tumor promoters of experimental colon cancer in rats. Calcium can inhibit their effects. After intestinal bypass (IB), fecal bile acid and lipid levels increase markedly. In rats, IB increases colonic cell proliferation and carcinogen-induced colon tumor incidence. Whether fecal bile acids and lipids influence rectal epithelial proliferation in humans is uncertain. This study compared rectal epithelial proliferation in IB subjects and in controls matched for age, sex, and body mass index and investigated the effects of calcium carbonate supplementation (2400 or 3600 mg Ca2+/day for 12 weeks) on proliferation indices in IB subjects. METHODS: Epithelial proliferation was studied by in vitro incubation of rectal biopsy specimens with [3H] thymidine. Twenty-four-hour stool collections were assayed for bile acids, lipids, and calcium. RESULTS: Whole crypt labeling index (LI) and upper crypt LI were increased in IB subjects compared with controls (P < 0.005). Calcium reduced whole crypt LI by 38% (P < 0.001) and upper crypt LI by 56% (P < 0.05). Levels of fecal bile acids (4.5 mmol/day) and lipids (131.9 g/day) were markedly elevated in IB subjects (P < 0.005). CONCLUSIONS: IB induces rectal hyperproliferation and expansion of the proliferative zone in association with excessive output of fecal bile acids and lipids. Oral calcium reverses the proliferative changes.

Administration, Oral↗
PubMed1994

Regression of gastric lymphoma of mucosa-associated lymphoid tissue with antibiotic therapy for Helicobacter pylori.

Regression of low-grade B cell gastric lymphoma of mucosa-associated lymphoid tissue after eradication of Helicobacter pylori with antibiotic therapy was recently shown in a small number of patients with low-volume tumors. A patient with a > 10 cm nodular gastric mucosa-associated lymphoid tissue lymphoma that caused hematemesis and weight loss is described. Antibiotic therapy of H. pylori resulted in full clinical recovery and resolution of the mass lesion and morphological features of lymphoma on routine histological examination. However, monotypic immunostaining of plasma cells persisted in a separate and grossly normal-appearing region of the stomach. Antibiotic therapy may be of benefit in patients with mucosa-associated lymphoid tissue lymphoma with mass lesions and significant signs and symptoms, but periodic search for residual lymphoma is needed.

Female↗
PubMed1994

Effect of corticotropin releasing factor on atrial natriuretic peptide release from the isolated perfused rat heart.

The effect of corticotropin releasing factor (CRF) on atrial natriuretic peptide (ANP) release and its possible modulation by indomethacin, norepinephrine, propranolol and nitro-L-arginine (an inhibitor of the endothelium-derived relaxing factor (EDRF) release) was investigated, using an isolated perfused rat heart preparation. Bolus injection of 5 micrograms CRF, dissolved in 100 microliters perfusion buffer, provoked a significant (p < 0.01 vs. control) short-time increase of ANP release. Indomethacin (3 x 10(-5) mol/l) inhibited the CRF-stimulated increase of ANP release and decreased the basal ANP secretion (p < 0.01 vs. CRF group). Norepinephrine (10(-9) mol/l) slightly, but not significantly, decreased the CRF-stimulated ANP release and did not change the basal ANP output. Propranolol (3 x 10(-6) mol/l) did not alter ANP release. Nitro-L-arginine (3 x 10(-5) mol/l) increased the basal ANP release (p < 0.01 vs. CRF group) and prolonged the CRF-induced rise of the ANP secretion. The present data suggest that prostaglandins are important mediators of basal and CRF-stimulated ANP release and that EDRF might be a physiological inhibitor of ANP release.

Animals↗
PubMed1994

[The effectiveness of Salmonella immunization of broiler breeders on the Salmonella colonization of the animals and their progeny after experimental oral infection].

The immunization of broiler breeder birds with Salmonella typhimurium live or inactivated vaccines (orally and/or parenterally administered) resulted in a considerable antibody response. Maternally produced antibodies were transferred via egg to the progeny. But the transferred antibodies did not increase considerably the resistance of 1 day old chickens to oral Salmonella typhimurium infection. The results of the oral challenge of the broiler breeder birds showed the protective effect induced by the oral immunisation with the Salmonella live vaccine strain. This protection is expressed by a reduced number of salmonella organisms in the caeca and internal organs.

Animals↗
PubMed1993

Effects of caloric restriction and dietary fat on epithelial cell proliferation in rat colon.

Epidemiological studies indicate that caloric intake and dietary fat content influence colonic carcinogenesis. In rodents, caloric restriction reduces, and some fats increase, carcinogen-induced colon cancer incidence. The present study was designed to investigate the effects of caloric restriction on colonic cell proliferation (CCP) in carcinogen-treated or control rats fed low- or high-fat diets. F344 rats were treated with azoxymethane (15 mg/kg x2) and then fed an isocaloric AIN 76A diet containing either 5 or 23% corn oil, ad libitum or calorie-restricted to 70 or 80% of the kilocalories consumed by ad libitum rats. Biopsies of the distal colon were taken at 10 and 20 weeks, and rats were sacrificed at 21 or 34 weeks on the experimental diets. Distal CCP was determined by microautoradiography after [3H]thymidine labeling in vitro or presacrifice administration in vivo. The labeling index and number of labeled cells per crypt column were significantly reduced by caloric restriction at all time points (10, 20, 21, 34 weeks). Caloric restriction reduced CCP in high fat- and low fat-fed rats and in azoxymethane-treated and control rats. High fat resulted in decreased CCP in the distal colon compared to low fat at 34 weeks but not earlier. The findings indicate that: (a) caloric restriction is effective in favorably modulating CCP, an intermediate biomarker of colon cancer risk; (b) a high fat ad libitum diet, which increased tumor yield, does not increase distal colon proliferation; (c) dietary fat intake alters proliferation in a manner differing from that induced by changing dietary caloric intake.

Animals↗