PubMed Health⌕ Search

Biomedical subjects

R Bader

Publications and source records attributed to R Bader.

At least 55 records · Page 3Linked to original sources
PubMed1992

Dose-response relationships of alimentary PtCl2 and PtCl4 in growing rats.

In experiments with rats dose-response relationships of alimentary PtCl2 and PtCl4 were investigated. 2 x 81 animals weighing 35 g were randomly distributed among 9 treatment groups which were fed ad libitum with a synthetic diet containing various amounts of Pt during 4 weeks. Pt was added in the form of PtCl2 or PtCl4 in the amounts 0; 0.01; 0.05; 0.10; 0.50; 1.0; 5.0; 10 and 50 mg/kg diet. The Pt supplementation had no influence on life mass gain or food consumption. In the case of 50 mg/kg Pt in the form of PtCl4 the erythrocyte count and hematocrit were reduced by about 13% in comparison with the control group. Dependent on the Pt dose, the application of PtCl4 and PtCl2 induced Pt retention in nearly all tissues especially in kidney. The effects were greater with PtCl4 than with PtCl2. As a result of the higher Pt retention in the kidneys, the serum creatinine was increased for the higher doses of PtCl4.

Animals↗
PubMed1991

Absence of xanthine oxidoreductase activity in human myocardium.

STUDY OBJECTIVE: The aim was to examine whether or not xanthine oxidase activity may be a significant source of oxygen derived free radicals in the human heart. DESIGN: Xanthine oxidoreductase activity of human myocardium was assayed in vitro. In addition, tests were performed to assess whether or not endogenous inhibitors of the enzyme were present in myocardial homogenates. The enzyme assay was based on high performance liquid chromatography with electrochemical and/or radiochemical detection of hypoxanthine, xanthine, and urate. SUBJECTS: Measurements were done on (a) isolated perfused rat myocardia and (b) left ventricular needle biopsies and papillary muscles obtained during elective cardiac surgery (chiefly aortic and/or mitral valve replacement and aortocoronary bypass) (n = 105 patients). MEASUREMENTS AND MAIN RESULTS: Homogenisation of human papillary muscles in buffer caused significant accumulation of hypoxanthine but not xanthine or urate. In addition, during incubation of crude myocardial homogenates with exogenous xanthine or hypoxanthine in the presence of NAD+ and/or O2 no production of urate was detected. Likewise, following aerobic incubation of papillary muscle homogenates with 14C-hypoxanthine neither 14C-xanthine nor 14C-urate were formed. Absence of xanthine oxidising activity was also observed with human papillary muscle extracts that were subjected to either ultrafiltration or gel filtration. In contrast, the rat heart was found to contain abundant xanthine oxidoreductase activity. The rat heart enzyme was inhibited by both allopurinol and oxypurinol but remained active when mixed with human papillary muscle homogenates. CONCLUSIONS: These findings show absence of xanthine oxidase and xanthine dehydrogenase activities in human myocardium, indicating that xanthine oxidase is not a source of oxygen derived free radicals in the human heart.

Adolescent↗
PubMed1990

The influence of ethanol on the stem cell toxicity of benzene in mice.

BDF1 mice were exposed to 100, 300, and 900 ppm benzene vapor, and the numbers of hematopoietic progenitor cells, early and late erythroid progenitors (BFU-E and CFU-E) and granuloid progenitors (CFU-C), were determined with and without additional exposure to ethanol (5, 10, 15 vol%) in the drinking water. The duration of benzene inhalation was up to 4 weeks, 6 hr per day, 5 days per week. It was shown that the number of CFU-E per femur was depressed in a dose-dependent manner by benzene alone and also by ethanol combined with a given benzene concentration. CFU-E showed rapid regeneration after the end of the exposure, but not BFU-E and CFU-C. Prolongation of the ethanol exposure after withdrawal of benzene had only a marginal effect on progenitor cell regeneration.

Administration, Inhalation↗
PubMed1989

Automatic image analysis as a valuable aid for the objective assessment of the enlargement of hepatocytes in toxicological studies.

Evaluation of histopathological slides is a subjective science; objectivity is needed, especially with minimal alterations. Quantitation using measurement procedures is of special value in toxicological studies. The present study tests a method in which the hepatocytic nuclei were measured per area of liver tissue, excluding the sinusoidal space. Different grades of hepatocellular enlargement were induced by different dose levels of a test compound (combination of two diuretics). The method demonstrates the well-established dose dependence of liver cell enlargement and permits differentiation between slight drug-induced enlargement and the normal variation in cell size. Special reference is made to avoid measurement artefacts.

Animals↗
PubMed1989

Binding of von Willebrand factor to glycoproteins Ib and IIb/IIIa complex: affinity is related to multimeric size.

We have separated von Willebrand factor (vWF) multimers of different size into several fractions which were characterized by SDS-agarose gel electrophoresis and by measuring the ratio between ristocetin cofactor activity (Ricof) and von Willebrand antigen (vWF:Ag) content. The pooled fractions contained vWF with multimeric structures and Ricof similar to those in plasma. The pool was labelled with 125I and used for inhibition binding studies with individual fractions to calculate the dissociation constants (Kd values expressed in mol/l) of the individual fractions for ristocetin-dependent binding to GP Ib and thrombin-induced binding to GP IIb/IIIa. Direct binding studies of the 125I-vWF pool gave mean Kd values of 2.02 +/- 0.05 x 10(-8) for GP Ib and 1.15 +/- 0.02 x 10(-8) for the GP IIb/IIIa complex. Inhibition binding studies gave Kd mean values one third to one tenth as high for larger multimers and 3-10 times higher for smaller multimers, for both GP Ib and IIb/IIIa complex. Similar results were observed when binding studies were carried out in the presence of platelets from a patient with afibrinogenaemia. These data on binding correlated very well with ristocetin- and thrombin-induced aggregation of afibrinogenaemic platelets, since equal concentrations of the higher molecular weight forms gave significantly higher aggregation rates. Based on these results, we conclude that the affinity of the vWF molecule for its two platelet receptors is greater for the largest multimers.

Afibrinogenemia↗
PubMed1989

[Hepatobiliary actinomycosis. Apropos of 3 cases with pseudocancerous aspects].

Three cases of hepatobiliary actinomycosis are reported. In all cases, carcinoma was initially suspected. One patient underwent cytoaspiration under sonographic guidance. Diagnosis was obtained by autopsy in one case, laparotomy and biopsy in the other cases. Confusion with cancer is frequent in actinomycosis, especially in hepatic lesions.

Actinomycosis↗
PubMed1989

[A rare etiology of acute occlusion of the small intestine: anisakiasis. Review of the literature apropos of a case].

The authors report a case of acute small bowel occlusion related to anisakis. This parasitis is due to ingestion by man, an unusual host, of a nematode of "anisakis" type at larva stage, a parasite to be found in numerous species of raw or home-processed fish. The parasite whose symptomatology is aspecific, can be located on the whole digestive tube. Diagnosis suggested by medical inquiry along with eosinophily, can be confirmed by serology and discovery of the parasite after anatomo-pathologic analysis. Medical treatment consisting in associating anti-parasite medicines with corticoids in certain cases, is recommended in diffuse forms and allergic signs of disease. Surgical complications make the laparotomy necessary for appropriate diagnosis and curing of the patient. Increasing frequency of this pathology shows the importance of prophylactic measures such as: abstaining from raw or home-processed fish, cooking fish at a temperature of 60 degrees C, deep-freezing fish at a temperature of -20 degrees C for 24 h at least, before eating it raw.

Acute Disease↗
PubMed1988

Cell-specific immuno-probes for the brain of normal and mutant Drosophila melanogaster. I. Wildtype visual system.

We have screened antibodies for immunocytochemical staining in the optic lobes of the brain of Drosophila melanogaster. Seven polyclonal antisera and five monoclonal antibodies are described that selectively and reproducibly stain individual cells and/or produce characteristic staining patterns in the neuropile. Such antisera are useful for the cellular characterization of molecular and structural brain defects in visual mutants. In the wildtype visual system we can at present separately stain the following: the entire complement of columnar "T1" neurons; a small set of presumptive serotonergic neurons; some 3000 cells that contain and synthesize gamma-amino butyric acid (GABA); and three groups of cells that bind antibodies to Ca2+-binding proteins. In addition, small groups of hitherto unknown tangential cells that send fine arborizations into specific strata of the medulla, and two patterns of characteristic layers in the visual neuropile have been identified by use of monoclonal antibodies generated following immunization of mice with homogenates of the brain of Drosophila melanogaster.

Animals↗
PubMed1988

Oligospecificity of the cellular adhesion receptor Mac-1 encompasses an inducible recognition specificity for fibrinogen.

Mitogenesis, cellular aggregation, and motility follow upon the interaction of fibrinogen with certain defined cell surface receptors. In addition to circulating platelets and vascular endothelium, monocytes express what appears to be a receptor for fibrinogen. Evidence is presented here that the leukocyte adhesion receptor Mac-1 can be specifically induced to bind fibrinogen with characteristics immunochemically and functionally distinct from the established Arg-Gly-Asp-directed fibrinogen receptors. The competence of Mac-1 as a fibrinogen receptor is a general property of cells of monocyte and myeloid lineage acquired after maturational changes of some regions of the alpha subunit of Mac-1 during the process of cell differentiation. This ligand recognition specificity of Mac-1 is lacking for the resting cell. Rather, induction of fibrinogen binding capacity of Mac-1 is due to a cellular response to selected agonists characterized by inducing rapid transients of cytosolic Ca2+. Although different in activation pathways and recognition specificity, Mac-1 exhibits an oligospecific ligand versatility characteristic of other homologous Arg-Gly-Asp-directed adhesion receptors.

Amino Acid Sequence↗
PubMed1988

[A rare cause of neonatal occlusion by a palpable abdominal mass: Meckel's diverticulum].

The authors report an unusual case of newborn obstruction by Meckel's diverticulum. Symptoms were repeated vomiting and a rounded mass was palpated in right lower quadrant. This mass looked like a fecalith on X Rays which also showed dilated gas filled loops of intestine. A barium enema showed no trouble of rotation, a good filling of last loops of small bowel, then a large kind of pocket, filled from the bowel. Operation discovered a huge (6 x 5 cm) Meckel's diverticulum compressing small intestine and pushing the cecum towards the upper quadrant. Treatment was ileal resection followed by end to end anastomosis. A very few newborn obstructions by Meckel's diverticulum were published; mechanisms are intussusception, volvulus, herniation. No similar case as reported was found in literature.

Age Factors↗
PubMed1987

High-quality MR imaging with flexible transmission line resonators.

A novel type of surface coil suitable for human magnetic resonance (MR) imaging is described. The radio frequency receiving unit consists of a coaxial transmission line resonator (TLR). Its high filling factor and loaded Q-value of about 140 result in a high signal-to-noise ratio and thus a high-quality image. The coaxial Faraday shield eliminates di-electric losses and capacitive detuning of conductive samples. The stabilizing effect of the TLR makes it unnecessary to tune the coil between imaging of patients. The TLR can be immediately adapted to the individual body contours of a patient. Regions of the body traditionally difficult to image (e.g., throat) are easily examined due to the flexibility of the coaxial cables. These advantages coupled with ease of handling and shorter preparation time have made the TLR a proved tool that has been successfully used in many areas of diagnostic MR imaging.

Equipment Design↗
PubMed1987

[False aneurysm of the superior mesenteric artery complicating a pancreatic pseudocyst].

The authors report a case of false aneurysm of the superior mesenteric artery, complicating acute pancreatitis. They insist on the sonographic signs of "the cyst within a cyst"; the presence of a cystic lesion located within a larger mass an US Scanning is highly suggestive of a false aneurysm included in a pseudocyst. They demonstrate the correlation between US Scanning, CT Scan and arteriogram.

Aneurysm↗
PubMed1987

Increased surface expression of the membrane glycoprotein IIb/IIIa complex induced by platelet activation. Relationship to the binding of fibrinogen and platelet aggregation.

Platelet activation altered the binding of three monoclonal antibodies (monovalent Fab' fragment) directed against the glycoprotein (GP) IIb/IIIa complex. An increased binding of two- to threefold occurred after stimulation with thrombin or phorbol myristate acetate (PMA), with slight but significant increase in the dissociation constants (Kd) of two antibodies (LJ-CP8 and LJ-P9). In contrast, no statistically significant changes were observed with ADP-stimulated platelets. The increased binding of LJ-CP3, but not of the other two antibodies, to activated platelets decreased by 30% to 40% in the presence of EDTA at 22 to 25 degrees C. Platelets stimulated by thrombin or PMA bound more fibrinogen than did those stimulated by ADP, and significant differences in the extent but not in the affinity of fibrinogen binding were observed with various platelet agonists. When the pool of GP IIb/IIIa molecules exposed on the surface of unstimulated platelets was reacted with the monoclonal antibody LJ-CP3 to block ADP-induced fibrinogen binding and platelet aggregation, stimulation with thrombin or PMA still induced substantial binding of antibody and fibrinogen, and aggregation ensued. Therefore, platelets exposed to "strong" agonists exhibit an increased number of surface-oriented epitopes associated with GP IIb/IIIa. The GP IIb/IIIa molecules bearing these newly exposed epitopes are functional in that they can bind fibrinogen and mediate platelet aggregation.

Antibodies, Monoclonal↗
PubMed1986

Heterogeneity in type IIB von Willebrand disease: two unrelated cases with no family history and mild abnormalities of ristocetin-induced interaction between von Willebrand factor and platelets.

Two patients from two separate families were diagnosed as having type IIB von Willebrand disease, because they had lifelong bleeding tendencies, prolonged bleeding times, no large von Willebrand factor multimers, and low levels of ristocetin cofactor in plasma with heightened ristocetin-induced platelet aggregation. There was no history of bleeding, and no laboratory abnormalities were found in the parents and sibship of either propositi, in contrast with the autosomal dominant pattern of inheritance usually observed in type IIB von Willebrand disease. Abnormalities of ristocetin-induced von Willebrand factor-platelet interactions were less severe than in a patient from a previously reported family with type IIB von Willebrand disease studied in parallel. The peculiar features of these cases provide additional evidence of the existence of heterogeneity within this variant.

Blood Platelets↗