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Biomedical subjects

J Schmitz

Publications and source records attributed to J Schmitz.

At least 199 records · Page 11Linked to original sources
PubMed1985

Investigation of mine and industry dumps in the FRG in relation to a possible release of natural radioactive elements.

More than 350 dumps of mines and industries in two federal states of the FRG were recorded, measured radiometrically, evaluated, and some of them sampled. Most of the mine dumps belonged to old and smaller residues from lead/zinc and iron ore mining, while the largest depositions contain tailings of modern ore beneficiation or flyash disposal. All mine dumps from uranium exploration in Baden-Württemberg and Bavaria were investigated. The highest doses, up to 100 mSv/a, were found on the piles of the uranium exploration. These depositions, which are supervised and licensed, are followed, in terms of surface dose, by the old uncontrolled mine dumps of silver/cobalt mining with doses up to 20 mSv/a. The numerous porphyry and granite quarries show doses between 1 and 2 mSv/a, as do flyash and slag dumps. The lowest doses were found on the dumps of the hydrothermal Pb/Zn and iron ore deposits, while the slag piles of iron ore processing showed higher thorium values. Assays for Ra-226 and Pb-210 of the materials deposited confirmed the radiometric results. Analyses of seepage waters and gallery waters showed only very few values exceeding the derived drinking water concentrations.

Environmental Pollution↗
PubMed1985

[Decrease of the cytotoxicity of gliadin fractions in the development of celiac disease. Organotypic culture study].

Observation up to adulthood of children with coeliac disease given again a normal diet had shown a clinical as well as histologic reduction in their sensitivity to gluten. From this fact a retrospective study was undertaken to appreciate whether this decreased sensitivity was also observed in vitro in a model of organotypic culture of intestinal mucosa obtained by biopsy, in the presence of gliadin toxic peptides. Twelve children had 2 cultures with a several year interval under normal diet. In 10 of them a decreased cytotoxic effect was observed. However, the explanation of this decrease remains difficult. It seems related neither to the age of the children, nor with the status of the mucosa at the time of in vitro testing, or to the duration of the gluten-containing diet. This study finally confirms that it is impossible to use organotypic cultures as an in vitro test for the diagnosis of coeliac disease.

Celiac Disease↗
PubMed1984

The effects of alpha 2-adrenergic and serotonergic receptor antagonists on cyclic blood flow alterations in stenosed canine coronary arteries.

Platelets possess alpha 2-adrenergic and serotonergic (5-hydroxytryptamine) receptors which are thought to mediate the in vitro proaggregatory effects of epinephrine and serotonin, respectively. However, their importance in platelet aggregation in vivo is uncertain. In the present study, we evaluate the ability of yohimbine and ketanserin, relatively selective alpha 2-adrenergic and serotonin antagonists, respectively, to alter cyclic flow reductions in stenosed coronary arteries in open-chest, anesthetized dogs. These cyclic flow reductions, characterized by progressive declines in coronary blood flow interrupted by abrupt and, often spontaneous, restorations of flow, were produced by cylindrical constrictors placed on the left anterior descending coronary artery. A pulsed Doppler flow probe, placed proximal to the constrictor, was used to measure coronary blood flow. Regional myocardial blood flow was measured with 15-micron radiolabeled microspheres before coronary constriction and when coronary blood flow appeared to be at its nadir and zenith during cyclic flow reductions. After the cyclic flow reductions had been observed for 1 hour, yohimbine (1-2 mg/kg), ketanserin (0.25 or 0.5 mg/kg), or saline was given, and coronary blood flow and hemodynamics were monitored for another hour. The frequency of cyclic flow reductions and the mean of the three lowest nadirs of coronary blood flow (mean +/- SE) were compared between the first and second hours. Ketanserin, at doses of 0.25 and 0.50 mg/kg, virtually abolished cyclic flow reductions in all dogs tested. Yohimbine [1 mg/kg ( n = 14)] was partially effective in reducing the frequency (9.6 vs. 5.5 cyclic flow reductions/hr) and severity of cyclic flow reductions (nadirs of coronary blood flow = 6.2 +/- 2.4 vs. 20.9 +/- 6.1% of control). A higher dose of yohimbine [2 mg/kg (n = 7)] was no more effective. The frequency (9.3 +/- 0.9 vs. 9.3 +/- 1.0 CFR/hr) and severity (17.4 +/- 5.4 vs. 12.4 +/- 3.9% of control coronary blood flow) of cyclic flow reductions were not changed by saline. The relatively selective alpha 1-adrenergic antagonist, prazosin (0.01 mg/kg, iv), and the beta-adrenergic antagonist, propranolol (1-2 mg/kg, iv), did not affect the frequency or severity of cyclic flow reductions. Thus, the abilities of yohimbine to inhibit and ketanserin to abolish cyclic flow reductions in stenosed canine coronary arteries suggest that serotonin and, possibly, alpha 2-adrenergic agonists may influence cyclic flow alterations importantly in this model.

Adenosine Diphosphate↗
PubMed1984

Effect of TEPC-183 plasmacytoma on resistance of passively or actively immunized BALB/c mice to infection with Streptococcus pneumoniae.

This study focuses on the effect of TEPC-183 (tetramethylpentadecane)-induced plasmacytoma on resistance of mice to infection with Streptococcus pneumoniae type III. Vaccination of normal or of TEPC-183-bearing mice with either a polyvalent pneumococcal vaccine (Pnu-Imune) or purified polysaccharide type III protects both against challenge with live S. pneumoniae. However, a 38-fold increase in susceptibility of the tumor-bearing mice over that of controls was observed. Immunized splenectomized mice were ten times more susceptible to infection than were immunized normal mice. However, this increased susceptibility of splenectomized mice could be overcome by passively administered antibody. In passive protection experiments, antisera obtained from normal and TEPC-183-bearing or from cyclophosphamide-treated mice were almost equally protective. A 6-fold increase of antibody (133 ng of antibody), however, was required to protect TEPC-183-bearing mice against challenge with 500 organisms, as compared with the 22 ng of antibody required to protect normal mice, indicative of defective host defense mechanisms in addition to the lower production of antibody in the TEPC-183-bearing mice. In contrast, mice bearing an equal tumor load of Sarcoma 37 behaved similarly to normal mice, showing that the increased susceptibility to infection was due to TEPC-183, a particularly immunosuppressive tumor.

Animals↗
PubMed1983

Intestinal malignant lymphoma in a child with familial celiac disease.

A case of intestinal malignant lymphoma occurring in a 10-year-old North African girl with celiac disease is reported. Celiac disease was diagnosed at age 4. A gluten-free diet was started and was maintained for the next 6 years. Seven months after the patient returned to a normal diet, clinical symptoms and subtotal villous atrophy relapsed. Within the next month an abdominal malignant lymphoma was diagnosed. After chemotherapy the tumor disappeared but recurred 6 months later, involving the colon and the liver. Death occurred shortly thereafter. A brother, two years older, also with proven celiac disease, is presently on a strict gluten-free diet. Both children shared the same histocompatibility antigens (HLA A2-B17/A29-B12, identity at the D locus). Whether or not relapse of celiac disease played a role in the appearance of the tumor remains highly speculative; however, the case of our patient suggests that familial involvement and, in some instances, ethnic origin may constitute risk factors predisposing to malignancy.

Celiac Disease↗
PubMed1983

Improvement of uremic neuropathy and hypogeusia by dialysate zinc supplementation: a double-blind study.

A reduction in the plasma zinc concentration is a well-recognized complication of hemodialysis. A positive clinical response to zinc therapy under controlled conditions is the most reliable criterion of zinc deficiency. Zinc therapy using a nonproprietary zinc dialysate was evaluated in 12 dialysis patients with proven hypogeusia and polyneuropathy, in a randomized double-blind crossover comparison (preliminary phase, 4 weeks; placebo phase, 12 weeks; initial phase, 12 weeks; final phase, 6 weeks; post phase, 4 weeks). The dosage was related to the zinc plasma and erythrocyte levels, measured weekly. Nerve conduction velocity (NCV) and taste-testing were used to evaluate the effect of treatment at the end of the placebo and therapy phases. There was significant reduction in the recognition and determination threshold level for each of the four qualities of taste. The NCV improved significantly. The plasma zinc level could be elevated in all patients to the desired concentration, using individualized supplementation of dialysate with zinc. The erythrocyte zinc level remained constant, at double the normal value. The plasma zinc concentration fell back to the initial level 6 weeks after conclusion of therapy. We conclude that (1) zinc substitution may provide a specific therapy for uremic polyneuropathy, (2) the observed hypogeusia results from zinc deficiency, (3) long-term therapy is necessary to obtain a constant normal plasma zinc concentration, (4) zinc substitution by dialysate is a suitable and nonstressful method of administration.

Adult↗
PubMed1983

Longitudinal study of the human intestinal brush border membrane proteins. Distribution of the main disaccharidases and peptidases.

The longitudinal distribution of the main brush border membrane hydrolases was studied in six entire human small intestine, one of which was found to be lactase-deficient. Sucrase and lactase activities were found to be highest in the jejunum, whereas glucoamylase activity rose steadily and reached its highest activity near the ileocecal valve. Maltase activity distribution was intermediate between that of sucrase and of glucoamylase. Neutral aminopeptidase, acid aminopeptidase and dipeptidyl peptidase IV activities tended to increase toward the end of the small bowel, the latter two activities rising more than the first one. Furthermore, the protein compositions of the brush border membrane in the jejunum and in the ileum were compared after electrophoresis on polyacrylamide gels and crossed-immunoelectrophoresis; protein patterns were found to be similar along the gut, and enzyme-specific activities varied in parallel with the amounts of their corresponding proteins. In the lactase-deficient intestine, the protein band corresponding to lactase was not visible. Maximal digestive capacity was thus localized in the jejunum only for disaccharides, and in the ileum for the more complex substrates, oligosaccharides, and peptides; this finding suggests that the ileum may play a greater role in their terminal digestion than is usually admitted.

Adolescent↗
PubMed1982

Fat absorption in low birthweight infants.

Studies on the incomplete fat absorption in newborns, particularly preterm ones, are reviewed. In the first week term breastfed newborns have a fat absorption coefficient of 91%. Lyophilization or pasteurigation reduces this figure in term as well as in preterm newborns. Excess Ca++ lowers fat absorption. So far, there is no evidence of immaturity of intracellular fat transport through the enterocyte. In the newborn low pancreatic lipase activity and low intraluminal bile salt concentrations appear to limit fat absorption. The most effective method to improve fat absorption in preterm babies seems to substitute part of the milk fat by medium-chain triglycerides.

Animals↗