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Biomedical subjects

W Fischer

Publications and source records attributed to W Fischer.

At least 325 records · Page 18Linked to original sources
PubMed1982

[Mannan localization with concanavalin A in conjunction with electron microscopy and chemical analysis of differently prepared cell walls of the food protein yeast Candida spec. H].

Regions of different electron densities after concanavalin A-peroxidase-reaction have been observed in cell walls of intact cells as well as in isolated cell walls: In the peripheral region of intact cell walls two mannan layers appear. Treating isolated cell wall with pronase, NaOH, ethylendiamine or citrate buffer, respectively, we find on A binding spots in the inner cell wall regions which appear electron transparent in the untreated cell walls. Apparently the mannan component of the inner cell wall regions is masked by proteins. In correspondence with chemical analysis our results cannot confirm the existence of inner cell wall regions which are free of mannan.

Candida↗
PubMed1982

Ultrastructural alterations at the cell wall and plasma membrane of Candida spec. H induced by n-alkane assimilation.

The ultrastructure of n-alkane-grown cells of Candida spec. H was investigated by thin sectioning and freeze-etching techniques. On the plasma membrane shallow depressions could be observed. n-Alkane deposits were localized within the cell wall and at the plasma membrane. Peri-plasmic multilamellar structure appear in connection with n-alkane accumulation. Their participation in hydrocarbon assimilation and the nature of the lamellar structures are discussed.

Alkanes↗
PubMed1982

Reciprocal distribution of hexokinase and glucokinase in the periportal and perivenous zone of the rat liver acinus.

Glucokinase and hexokinase activities were measured in the periportal and perivenous zone of the liver acinus separated by microdissection. A microfluorimetric assay was established for the separate determination of both enzyme activities. Glucokinase activity was about 3.5-fold higher in the perivenous than in the periportal zone in fed male and female rats. after 24 h starvation this gradient was only slightly changed. Hexokinase showed an inverse gradient with about 1.5-fold higher activities in the periportal than in the perivenous zone in both fed and fasted animals. Since glucokinase is restricted to parenchymal cells and hexokinase is present predominantly or even exclusively in non-parenchymal cells, the heterogeneous distribution of glucokinase activity supports the model of a "metabolic zonation of liver parenchyma" with a predominance of glucose uptake in the perivenous and glucose release in the periportal hepatocytes.

Animals↗
PubMed1982

[Special treatment conditions in obstetric urogenital fistulas].

Reported in this paper is treatment of two African women for fistulae and incontinence. Findings recorded from one of them included total defect of the urethra and anterior wall of the rectum, including anus, as well as two vesicovaginal fistulae. Four operations were performed on her within 16 months, with sigmoid preternatural anus, hysterectomy, and restoration of vesical integrity being the only possible ways to remedy. Attempts for restoration of the urethra failed. Her absolute urinary incontinence was improved to stress-dependent incontinence. - A large vesicocervical-vaginal fistula was recorded from the other patient on whom combined abdominovaginal hysterectomy and fistuloplasty as well as dura-sling operation were performed in three sessions, in the course of nine months. These were supplemented with an operation to lengthen the urethra. The two former approaches were successful in removing absolute incontinence, while the patient's functional urinary incontinence was cured by the two latter approaches. Some considerations of principle are derived from the two cases with regard to choice of methods and actual treatment.

Adolescent↗
PubMed1982

[Operative therapy of urinary incontinence. Preoperative requirements--operation methods--after care].

Optimum success may be obtained from those incontinence operations which form one coherent unity with presurgical and postsurgical measures. Full elucidation of the symptom of urinary incontinence has proved to be the most important preoperative necessity. More comprehensive urometric objectivation will be required for problems which cannot be answered by a minimum programme. Time-consuming diagnosis should be, basically, accompanied by conservative incontinence treatment, primarily for three reasons, substantiation of diagnosis, avoidance of meaningless surgery, and improvement of conditions for the operation proper as well as for its lasting success. - The sling operation, retropubic urethrocystopexy, and vaginoplasty are major groups in stress incontinence surgery which are described by illustrated examples. Reference is made to partial denervation of the urinary bladder as a possible therapeutic approach to urge incontinence. Proposals are made for proper choice of methods, in agreement with both the general state of the art and the author's personal experience. - Postoperatively, particular attention should be given to continued physiotherapy, endurance of adequate micturition without residual urine, and nephrological follow-up care of patients with urinary tract infection who had failed to respond to therapy. The difficulties implied in identification of lasting results may be seen from the findings obtained from follow-up examination of patients on whom pubococcygeal repair had been performed. Something between four and five months will be required for optimum multi-step therapy.

Female↗
PubMed1982

Analysis of the soluble cytoplasmic components of Mycobacteria and Nocardia by crossed immunoelectrofocusing.

Soluble cytoplasmic components of Mycobacterium tuberculosis, strain H 37 Ra, and Washington II, Mycobacterium bovis, strain BCG and Nocardia asteroides were analysed by isoelectric focusing, crossed immunoelectrophoresis, and crossed immunoelectrofocusing. Using con A-affinity chromatography con A-reactive polysaccharides could be separated from the cytoplasmic fraction which improved the focusing effect. The isoelectric focusing patterns of the various mycobacterial strains were similar, however, concentration differences of the respective components might occur. N. asteroides had a different pattern. By crossed immunoelectrofocusing it was shown that most of the bands of the focusing pattern had antigenic character. Con A-reactive polysaccharides were located near to the cathode, and the con A-nonbound antigens occured close to the anode. Cross-reaction between mycobacteria and N. asteroides was remarkable. In crossed-line immunoelectrophoresis four line in N. asteroides antigens were identical with the highest peaks of M. bovis, strain BCG antigens.

Antigens, Bacterial↗
PubMed1982

[Anticonvulsant effects of indoline derivatives].

The anticonvulsant activities of several indoline derivatives were tested in mice using the pentetrazole (PTZ) and electroshock seizure model. Furthermore, the toxicity and the influence on hexobarbitone anaesthesia were determined. 2-oxoindoline--the most potent anticonvulsant compound--shows a characteristic modification of PTZ-induced seizures, especially a suppression of the tonic phase and a marked prolongation of survival time at lethal PTZ-doses as well as in doses of 100 mg/kg a complete protection effect to maximum electroshock. The majority of indolines possess also a marked sedative effect. The LD50 values of the derivatives under investigation are differing considerably, however, majority of compounds being within the range of 300 to 800 mg/kg (i.p.).

Animals↗
PubMed1981

Molecular dynamics study of ion transport in transmembrane protein channels.

Ion transport through biological membranes often takes place via pore-like protein channels. The elementary process of this transport can be described as a motion of the ion in a quasi-periodic multi-well potential. In this study molecular dynamics simulations of ion transport in a model channel were performed in order to test the validity of reaction-rate theory for this process. The channel is modelled as a hexagonal helix of infinite length, and the ligand groups interacting with the ion are represented by dipoles lining the central hole of the channel. The dipoles interact electrostatically with each other and are allowed to oscillate around an equilibrium orientation. The coupled equations of motion for the ion and the dipoles were solved simultaneously with the aid of a numerical integration procedure. From the calculated ion trajectories it is seen that, particularly at low temperatures, the ion oscillates back and forth in the trapping site many times before it leaves the site and jumps over the barrier. The observed oscillation frequency was found to be virtually temperature-independent (nu 0 approximately equal to 2 X 10(12) s-1) so that the strong increase of transport rate with temperature results almost exclusively from the Arrhenius-type exponential dependence of jump probability w on 1/T. At higher temperatures simultaneous jumps over several barriers occasionally occur. Although the exponential form of w(T) was in agreement with the predictions of rate theory, the activation energy Ea as determined from w(T) was different from the barrier height which was calculated from the static potential of the ion in the channel; the actual transport rate was 1 X 10(3) times higher than the rate predicted from the calculated barrier height. This observation was interpreted by the notion that ion transport in the channel is strongly influenced by thermal fluctuations in the conformation of the ligand system which in turn give rise to fluctuations of barrier height.

Ion Channels↗
PubMed1981

Effect of alanine ester substitution and other structural features of lipoteichoic acids on their inhibitory activity against autolysins of Staphylococcus aureus.

Native substitution with the D-alanine ester of lipoteichoic acids (LTAs) affects their immunological properties, the capacity to bind divalent cations, and LTA carrier activity. In this study we tested the influence of the D-alanine ester on anti-autolytic activity, using extracellular autolysin from Staphylococcus aureus and nine LTAs with alanine/phosphorus molar ratios of between 0.23 and 0.71. The inhibitory activity, highest with alanine-free LTA, exponentially decreased with increasing alanine content, approaching zero at substitutions of greater than 0.6. Correspondingly, dipolar ionic phospholipids were not inhibitory, in contrast to negatively charged ones. Glycosylation of LTA up to an extent of 0.5 did not depress inhibitory activity, and even at a degree of 0.8 the effect was comparatively small. On comparison of LTAs from various sources, differences in lipid structures and chain lengths were without effect. The inhibitory activity drastically decreased when the glycolipid carried a single glycerophosphate residue or the hydrophilic chain had the unusual structure [6 leads to Gal(alpha 1--6)Gal(alpha 1--3)Gro-(2 comes from 1 alpha Gal)-P]n, in which digalactosyl moieties connect the alpha-galactosylated glycerophosphate units. Principally, the same results were obtained with the more complex system of autolysis of S. aureus cells. We hypothesize that the anti-autolytic activity of LTA resides in a sequence of glycerophosphate units and that the negative charges of appropriately spaced phosphodiester groups play a crucial role. The alanine ester effect is discussed with respect to the putative in vivo regulation of autolysins by LTA.

Alanine↗