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Biomedical subjects

L Müller

Publications and source records attributed to L Müller.

At least 163 records · Page 9Linked to original sources
PubMed1982

The phospholipid packing arrangement in small bilayer vesicles as revealed by proton magnetic resonance studies at 500 MHz.

Proton magnetic resonance spectra of saturated phospholipids in small unilamellar vesicles has been recorded at 500 MHz on a Bruker WM500 spectrometer. The additional spectral dispersion reveals new structure in the acyl chain resonances. At temperatures near the thermal phase transition, the chain methylene and methyl peaks are split, both showing a broad and a relatively sharp component. Magnetization transfer experiments together with studies in the presence of manganese ions inside or outside the vesicles indicate that the sharp component is to be assigned to the protons from the acyl chains in the inner half of the bilayer and the broad component to chains in the outer monolayer. These experiments demonstrate unambiguously that the extreme surface curvature intrinsic to small unilamellar vesicles induces a profound asymmetry in the packing arrangement of the hydrocarbon chains in the two leaflets of the bilayer and causes the two monolayers to exist in markedly different motional states.

Aged↗
PubMed1982

Different response of liver parenchymal cells from starved and fed rats to cadmium.

The susceptibility of hepatocytes to the deleterious effects of cadmium (10-100 microM Cd), as evidenced by SH-group content and cell membrane permeability for Trypan Blue (TB), was shown to be strongly dependent on the dietary condition of the donor animal. Although Cd stimulated lipid peroxidation (LPO) equally well in "starved" as in "fed cells", SH-group content and TB-exclusion decreased markedly only in "starved" cells exposed to Cd. Experiments with methionine + serine and/or the antioxidant (+)-cyanidanol-3 suggested that the Cd-dependent LPO proceeded independent of the decrease in SH-group content or TB-exclusion.

Animals↗
PubMed1982

The synthesis and transport of fucosylated glycans in the immature mouse cerebellum. An autoradiographic and microchemical study of differentiating cell and tissue compartments.

A study of 3H-fucose incorporation in the immature mouse parenchyma revealed that the rate of synthesis of fucosylated glycans in the neuropil of more differentiated internal granular layer, as well as in the PURKINJE cell bodies is higher than in the less mature external granular layer. The 3H-fucose incorporation into the choroid plexus, meninges, and blood vessel walls exceeds highly incorporation into the cerebellar parenchyma. A follow-up autoradiographic study revealed remarkable differences in the radioactivity of incorporated 3H-fucose in the "cell-body rich" and "cell-fibre rich" layers indicating transport of newly synthesized glycans from the perikarya of differentiating cells into their processes extending mainly into the molecular layer and the cerebellar medulla. It is assumed that the increased rate of 3H-fucose incorporation reflect 1. increasing complexity of the fucosylated glycans of differentiating cells 2. increase in the turnover of cell membrane components, 3. accelerated export of glycosylated compounds into the outgrowing fibres of differentiating cerebellar cells.

Animals↗
PubMed1982

[Devitalization and haemostasis by thermal destruction--results of enzyme-histochemical and histological examination of oviduct specimens, following tissue coagulation by means of endocoagulation or high-frequency current (author's transl)].

Semm's technique of endocoagulation has been used by the authors for haemostasis in endoscopic abdominal surgery at the Department of Gynecology and Obstetrics, University of Kiel since 1973. --Enzyme-histochemical and histological tests, all based on endocoagulation or high-frequency current procedures, were applied to 100 human fallopian tubes. Fifteen of them remained uncoagulated and were used for comparison. --Membrane ATPase, 5-nucleotidase, cytochrome-C-oxydase, and other essential enzymes in cellular metabolism were inactivated by temperatures in excess of 57 degrees C. These enzymes, consequently, were no longer detectable from enzyme-histochemical preparations, whereas active tissue regions, those which still contained vital cells, were stained black to brown. --Negative enzyme reactions occurred in response to a coagulation forceps temperature of 120 degrees C, when applied not less than 20 seconds. Residual enzyme activities were still recordable from certain tubal areas, when forceps temperatures below 120 degrees C had been used. In such cases coagulation was insufficient, particularly in the inner layers of tubes (epithelium, mucosa). Temperatures above 130 degrees C and coagulation lengths of more than 20 seconds proved to be unnecessary, since no improvement in results was thus achievable. Temperatures of 140 degrees C and more have changed coagulated tissue into "adhesive" and make it stick to the coagulation forceps. Instrument withdrawal can in such cases cause bleeding rather than the desired haemostatic effect.

5'-Nucleotidase↗
PubMed1981

A fluorescence study on the mobility of surface antigens of untreated tumor cells and of tumor cells undergoing cell-mediated lysis.

Heterologous (rabbit) antibodies were raised against murine P-815 mastocytoma cells of DBA/2 origin. Antisera and IgG preparations were highly cytotoxic, whereas Fab fragments thereof lost all activity. Fab fragments also showed a much lower avidity than IgG, both for tumor and normal DBA/2 and C57 spleen cells as measured by the release of iodinated Fab and IgG. Both preparations bound specifically to P-815 cells since they were capable of inhibiting T cell-mediated target cell lysis. The binding of IgG and monovalent Fab fragments was studied by fluorescence. Rhodamine-coupled IgG bound homogeneously in the cold and quickly formed patches upon warming but did not form caps even after prolonged incubation at 37 degrees C. Rhodamine-coupled Fab fragments also bound homogeneously. Their distribution was unaltered after incubation at 37 degrees C even when tumor cells formed uropod-like tails. Fab fragments, however, could be induced to cap with a second and third antibody layer. P-815 cells labeled with rhodamine-coupled Fab fragments were incubated with cytolytic T cells (CTL). The conjugates formed between CTL and fluorescent target cells were observed. No gross redistribution of surface antigens on target cells was observed even at late stages of the lytic process. CTL, therefore, do not seem to operate via a redistribution of surface antigens.

Animals↗
PubMed1980

The presynaptic grid: a new approach.

A new electron microscopic facility is described which enables systematic visualization of E-PTA-stained presynaptic grids in full en face position. This EM-facility is used to analyze the size and the number of dense projections of synaptic grids in different brain areas of the rabbit. The observations support the view that dense projections form an intrinsic part of all central synapses and are organized in a hexagonal or triangular pattern. The observation of annulate and horseshoe-shaped synaptic grids is in agreement with previous observations on synaptic connections with subsynaptic plate perforations. A non-normal frequency distribution of dense projections per synaptic grid with distinct peaks is suggestive for the existence of distinct size classes of synaptic contacts. Analyses of the frequency distribution of dense projections in different areas and at different levels below the pial surface in adult animals point to a specificity of the distinct size classes related to the afferent origin or the target cell they are projecting on. Investigation of grid size and number of dense projections during a period of rapid synaptogenesis reveals that newly formed synapses also have a specific size. The complementarity of dense projections and vesicle attachment sites implicit in the model of Akert et al. has been used to calculate the number of vesicle attachment sites per sq. micrometer on account of the density of projections per grid. The agreement between our values and those of Akert and Peper, based on the analyses of vesicle attachment sites in freeze-etch specimen, is striking. The possible implications of these observations in relation to synaptic efficacy and neuronal microcicuitry are discussed.

Animals↗
PubMed1979

[Analytical characterization of palatinit (author's transl)].

The reaction product of the catalytic hydrogenation of isomaltulose (palatinose) is a mixture of alpha-D-glucopyranosido-1,6-sorbitol and alpha-D-glucopyranosido-1,6-mannitol designated palatinit. Because of its high potential as a sugar substitute methods for the identification and characterization of hydrogenation products and for the determination of palatinit as an ingredient in food preparations and biological samples are required. Several working procedures are described in full detail including thin layer and gas chromatography as well as enzymatic and chemical determinations.

Chromatography, Gas↗
PubMed1978

The effect of first visual stimulation on incorporation of labelled leucine into cerebral cortex of binocularly deprived kittens.

One-month old kittens, binocularly deprived with hoods from birth, were used. Before the experiments in which visual stimulation was applied the brainstem of kittens was transected at the pretrigeminal level. Cortical EEG activity and ocular behavior indicated that the isolated cerebrum of preparations was usually awake during experiment. Patterned visual stimulation was directed to one hemisphere, while the other was used as a control. Visual stimulation evoked in some cases (in 8 out of 17) an increase of incorporation of labeled leucine into the proteins of the striate cortex. Electrophoresis on polyacrylamide gel did not reveal any differences in the pattern of insoluble proteins between the stimulated and control visual cortex. It is suggested that first visual stimulation may enhance the protein metabolism of striate cortex in young kittens. Some unknown up to now physiological factors (motivation, attention?) may be critical for these phenomena.

Animals↗
PubMed1977

[The therapeutic scope of oral anticoagulation].

Evaluation of the therapeutic range of oral anticoagulation for different commercial thromboplastins in comparison with Quick's human brain thromboplastin and Thrombotest is based on simultaneous performance of all methods for each blood sample, on strict adherence to the manufacturer's instructions and on adequate statistical analysis.

Blood Coagulation Tests↗