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Biomedical subjects

M Wagner

Publications and source records attributed to M Wagner.

At least 991 records · Page 55Linked to original sources
PubMed1984

The effects of sympathetic stimulation and adenosine on coronary circulation and heart function in diabetes mellitus.

The aim of the experiment was to clarify whether the altered coronary reactivity in diabetes mellitus might be caused by a general modification of the sympathetic responses. Six of 12 young mongrel dogs of both sexes were made diabetic with alloxan (560 mmol/kg). This amount of alloxan induced a clinically manifest diabetes, however the animals failed to develop ketosis. The remaining six dogs served as controls. The haemodynamic investigation was performed three months after the induction of diabetes. Under pentobarbital anaesthesia (133 mmol/kg) mean arterial blood pressure, blood flow in the left anterior descending coronary artery, myocardial contractile force of left ventricular wall and heart rate were recorded continuously and the conductivity of coronary arterial bed was calculated during electrical stimulation ( 8V , 1-2-4-8-20 s-1) of the cardiac plexus or during the intracoronary infusion of adenosine (30-60-120-240-480 nmol/kg/min). In alloxan-diabetic dogs electrical stimulation evoked vasoconstriction in the coronary arterial bed, while vasodilation was observed in metabolically healthy animals. The vasodilator effect of adenosine was significantly smaller in diabetic than in control dogs. On the other hand there were no differences either in the alterations of heart rate caused by adenosine or in those of myocardial contractile force induced by adenosine or electric stimulation between the two groups. It is concluded that general alteration of sympathetic responses is not, but rather a modified relation of the receptors to the vessel wall might be responsible for the altered vascular responses in diabetes.

Adenosine↗
PubMed1983

Ganglioside biosynthesis in rat liver. Characterization of UDPgalactose--glucosylceramide galactosyltransferase and UDPgalactose-GM2 galactosyltransferase.

The conditions for the quantitative determination of UDP-Gal:glucosylceramide galactosyltransferase and of UDP-Gal:GM2 galactosyltransferase in Golgi-enriched preparations of rat liver were optimized. Triton X-100 was the detergent routinely used as octyl glucoside acted as a galactose acceptor forming octyl lactoside. Manganese ions were required for full activity, but Co2+ and Mg2+ could substitute to some extent. The nucleotide pyrophosphatase activity of the Golgi preparations which interfered with the GL2-synthase assay was inhibited by addition of 20 mM IMP; the latter is without appreciable effect on the rate of GL2 synthesis. Apparent Km values for UDP-Gal were 130 microM and 140 microM with Gl2-synthase and Gm1-synthase, respectively. That for glucosylceramide was 80 microM with GL2-synthase; for GM2 it was 10 microM with GM1-synthase. Competition experiments with variable concentrations of the lipid acceptors showed that the two synthase activities are independent catalytic entities. The specific activity of GM1-synthase exceeds that of GL2-synthase by a factor of ca. 25 under the optimized conditions used here.

Animals↗
PubMed1983

Altered hyperemic response of the coronary arterial bed in alloxan-diabetes.

Reactive hyperemic responses of the coronary arterial bed, provoked by asphyxia or clamping of the coronary artery, were compared in alloxan-diabetic and metabolically healthy dogs. In alloxan-diabetic dogs the response of the coronary arterial bed lasted longer, and its reactivity to hypoxia was lower. Treatment with adenosine caused less vasodilation in diabetic animals than in controls. These changes may be due to the altered reactivity of diabetic vascular smooth muscle.

Adenosine↗
PubMed1983

Electron microscopic localization of receptors for aggregated beta 2-microglobulin on the surface of beta-hemolytic streptococci.

The presence and location of receptors for aggregated human beta 2-microglobulin (beta 2m) on the surface of group A, C, and G streptococci were studied by electron microscopic techniques. Ferritin-conjugated aggregates of human beta 2m were used in direct binding experiments. Ferritin-conjugated antibodies against beta 2m were employed in a two-step indirect binding assay where the streptococci were incubated with unlabeled beta 2m aggregates before the addition of antibodies. Similar results were obtained with these two methods. Among tested group C and G strains, some showed binding of beta 2m, whereas others were negative. In group A streptococci, beta 2m binding was localized to filamentous structures typical of M protein. In two M protein-negative group A strains, the reactivity was heterogeneous, revealing a majority of unlabeled, but also some heavily labeled streptococci. Morphologically, these beta 2m-binding bacteria exhibited M protein-like projections in contrast to the smooth surfaces of unlabeled cells.

Cell Membrane↗
PubMed1983

Renal blood flow alterations after temporary ischemia. An experimental model in the rabbit.

In an effort to investigate the efficiency of various pharmacological agents in protecting the kidney against normothermic ischemia, an animal model was developed and the post-ischemic hemodynamics in the renal cortex of rabbit kidneys were studied. Renal cortical blood flow was evaluated 5-30 min after 60 min of normothermic ischemia of the left kidney using 141Ce-, 51Cr-, and 85Sr-labelled microspheres. Control groups were subjected to sham operation. The right kidneys served as individual controls. Ischemic kidneys showed a significant weight increase independent of reperfusion. Furthermore, a transient highly significant increase of cortical blood flow was found with an absolute maximum about 10 min after termination of ischemia. This increase in cortical blood flow was paralleled by a highly significant decrease of vascular resistance.

Animals↗
PubMed1983

Morphological evidence for different types of IgG-Fc receptors in group A streptococci.

The binding of immunoglobulin G (IgG) from man and 14 animal species to Group A streptococcal cells was studied by electron microscopy. Only the IgGs of rhesus monkey and guinea pig did not bind to any of the streptococcal strains tested. Fc receptors were seen located on filamentous protrusions of the streptococcal cell wall either regularly or in focal distribution. On the inner surface of isolated cell walls no Fc receptors were detected. Both the different labelling patterns for different IgG and the results of inhibition studies with homologous and heterologous IgGs suggested the existence of different types of Fc receptors in the same strain. Further characterization of the receptors, including their location, was performed by studying their susceptibility to several proteolytic enzymes.

Animals↗
PubMed1982

[A new microglossary for biopsy pathology].

The documentation of surgical biopsy reports involves the ordering, processing and retrieval of their informative content. Large amounts of data require computerization, which in turn demands a hierarchical code for optimal exploitation. The best coded nomenclature at present is the Systematized Nomenclature of Medicine (SNOMED), which was developed from the Systematized Nomenclature of Pathology (1965) after a 10-year trial and systematic evaluation. This system is based on the principle of facet classification and was conceived especially for computerized data processing. A microglossary is a strict subset of diagnostic terms for one particular field, which has been chosen from the entire set of medical terms available. The microglossary for computerized processing of biopsy data, which is currently being developed at the Department of Pathology of Graz University, is presented in this paper.

Austria↗
PubMed1982

Adrenergic stimulation of isolated rat gastric mucosal cells. Effect on adenylate cyclase and 14C-aminopyrine uptake.

Adrenergic stimulation of the adenylate cyclase (AC)-cAMP-system and 14C-aminopyrine accumulation, an indirect measure of parietal cell H+-production, was studied in a different preparations of gastric mucosal cells. The beta 2-adrenoceptor agonist hexoprenaline activated AC of crude homogenates from the gastric corpus of mouse, rat, guinea-pig, hog, dog and man. In isolated rat gastric cells (20% parietal cells), treated by low power sonication, 10(-8) to 10(-3) mol/l adrenaline and hexoprenaline activated AC equally potently and efficaciously by maximally 170%. Isoprenaline proved to be less effective activating up to 80%. 5.10(-5) mol/l GMP-PNP augmented basal activity 8.5 times and reduced the maximal efficacy. Adrenaline and hexoprenaline activated AC by maximally 120%, isoprenaline by 40%. The potency of adrenaline was 4 times lower, that of hexoprenaline 2 and that of isoprenaline 4 times higher in the presence of GMP-PNP. Adrenergic stimulation was inhibited by the beta-adrenoceptor antagonist propranolol, the effect of alpha-adrenoceptor-blockade by phenoxybenzamine was less pronounced. In fractions with 7-80% of parietal cells, prepared by isopycnic centrifugation with Percoll, adrenaline and hexoprenaline activated AC or hexoprenaline enhanced the cellular levels of cAMP in parietal cell poor and rich fractions. The degree of activation in response to histamine correlated with the number of parietal cells. 14C-Aminopyrine uptake was increasingly stimulated through 10(-8) to 10(-5) mol/l hexoprenaline, maximally by doubling the basal accumulation. 10(-4) mol/l histamine was 8 times more effective. 3.10(-7) mol/l propranolol inhibited the effect of 10(-5) mol/l hexoprenaline by 80%. The data suggest the localization of beta-adrenoceptors (likely beta 2-adrenoceptors) on parietal and other nonidentified gastric cells. At the parietal cell, adrenaline and hexoprenaline initiate activation of AC and hexoprenaline leads to H+-production. The responses are small compared to the effect of histamine. Thus, beta-adrenoceptor agonists exert intrinsic activity in relation to H+-production. Their influence on stimulated secretion of isolated cells remains to be elucidated.

Adenylyl Cyclases↗
PubMed1982

[Fractures of the acetabulum (author's transl)].

The results of conservative and operative treatment of dislocated fractures of the acetabulum are compared. The types of fracture are described where surgical stabilisation is indicated. Depending of the type of fracture, the causes of unsatisfactory results following operative treatment are: primary lesions of the cartilage, difficulties with reduction and retention, septic complications. The aim of surgery is first of all the anatomic reconstruction of the supporting area of the acetabulum. 2/3 of our patients were operated between the 2nd and the 14th day. The lateral position with the extremity freely movable is recommended for dorsal and lateral approach. A trochanter traction screw with extension facilitates the operative reduction. It was possible to re-examine 45 of 64 cases after a period of between 2 and 13 years. Results were evaluated according to the scheme by Merle d'Aubigné. 35 patients had very good or good results, in 3 cases secondary arthrodesis was necessary and in one case a total hip prosthesis was implanted. Dislocated acetabular fractures should be be operated as soon as possible if conservative methods fail. Late reconstruction may also be successful. The lesion of the sciatic nerve is an absolute indication for operation. Satisfactory results can be achieved by anatomic reconstruction even in cases with multiple fragmentation.

Acetabulum↗
PubMed1982

[Are fractures of the upper ankle joint to be treated conservatively? (author's transl)].

By means of 796 fractures of the upper ankle-joint, the treatment and results of the therapy according to the conservative-viewpoints are going to be discussed. Comparing the results after operative treatment, conservative therapy today is only justified with fractures of th type A and B under the presumption that there is no subluxation of the talus of the latter mentioned. Bimalleolar fractures of the type A can also be treated conservatively with good results if the inner-ankle fracture has not resulted in the destruction of the ankle-fork. All other fractures should have open reduction and internal fixation. Special attention shall be paid to the reconstruction of the complex fibula-syndesmosis.

Adolescent↗
PubMed1982

Evaluation of the clinical applicability of proton beams in definitive fractionated radiation therapy.

We report on the treatment of 317 patients treated either wholly or in part with proton beams at the Harvard Cyclotron Laboratory. These include: 130 patients treated for definitive radiation therapy of choroidal melanoma; 17 patients treated for tumors of the base of skull, cervical spine and cranium, which abut structures of the central nervous system (CNS); 23 patients treated for sarcomas of soft tissue and bone; 65 patients treated for carcinoma of the prostate; 14 patients treated for carcinoma of the rectum and anus; and 23 patients treated for squamous carcinoma of the oral cavity and oro-pharynx. Data on causes of failure and morbidity of treatment are presented. Overall the results are judged to be extremely encouraging. In particular, the treatment of the choroidal melanomas and sarcomas abutting CNS structures have clear clinical value, and the treatment of prostatic tumors and tumors of the head and neck are thought to be promising.

Bone Neoplasms↗
PubMed1982

Agglutination of bacteria by a sialic acid-specific lectin of the snail Cepaea hortensis.

Aqueous extracts from lyophilized albumen glands of the garden snail (Cepaea hortensis) exhibit, after separation from a second lectin, a specificity against sialic acid-containing polymers. In agglutination studies with bacteria, the lectin interacts with all strains of group B streptococci (Streptococcus agalactiae) containing type-specific polysaccharides. In contrast, group B streptococci containing only protein type antigens as well as all strains of other Lancefield streptococcal groups and several other bacterial strains did not react.

Agglutination Tests↗
PubMed1982

The moon illusion: I. How high is the sky?

The most common explanations of the moon illusion assume that the moon is seen at a specific distance in the sky, which is perceived as a definite surface. A decrease in the apparent distance to the sky with increasing elevation presumably leads to a corresponding decrease in apparent size. In Experiment 1 observers (N = 24) gave magnitude estimates of the distance to the night sky at different elevations. The results did not support the flattened-dome hypothesis. In Experiment 2 observers (N = 20) gave magnitude estimates of the distance to the sky at points around a 360 degrees circle just above the horizon. The results were consistent with those of Experiment 1, and in addition, estimates were highly correlated with the physical distances of buildings at the horizon. In a third, control experiment, observers (N = 20) gave magnitude estimates of the distances of buildings at the horizon. A power function fit the relation between estimated and physical distance (exponent = 1.17) as well as the relation between estimates of the sky points above the buildings (Experiment 2) and estimates of building distances (exponent = .46). Taken together, the results disconfirm all theories that attribute the moon illusion to a "sky illusion" of the sort exemplified by the flattened-dome hypothesis.

Astronomical Phenomena↗
PubMed1982

[Encephalitis due to listeria monocytogenes: a complication of immunosuppressive therapy (author's transl)].

Two cases of encephalitis due to Listeria monocytogenes with lethal outcome are presented. The infection occurred during immunosuppressive treatment for panarteritis nodosa and sarcoidosis, respectively. The pathological-anatomical findings were a diffuse purulent meningoencephalitis in the first case and a focal rhombencephalitis with necrotizing inflammation of brainstem and cerebellum in the second one. Listerial infections of the adult are gaining increasing importance as severe complications of immunosuppressive treatment.

Adrenal Cortex Hormones↗