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Biomedical subjects

W Müller

Publications and source records attributed to W Müller.

At least 577 records · Page 32Linked to original sources
PubMed1988

Column chromatographic separation of cells using aqueous polymeric two-phase systems.

Cell separation using aqueous polymeric two-phase systems is well established. For separations of cells having similar partition coefficients a multistep countercurrent distribution procedure has to be used. However, its operation is limited by time and apparatus constraints. As an alternative strategy we have developed a chromatographic technique in which the dextran-rich phase of a dextran/polyethylene glycol (PEG) phase system is immobilized onto derivatized agarose beads. The PEG-rich phase is used as the eluent. Inclusion of PEG-fatty acid affinity ligand gradients into the eluent produces separations of mammalian erythrocytes based on the differential interaction between the fatty acid and the erythrocyte membranes. A model separation of dog and human erythrocytes has been carried out.

Cell Separation↗
PubMed1988

c-fos expression interferes with thymus development in transgenic mice.

To study the function of the proto-oncogene c-fos in hematopoietic tissues, transgenic mice were generated that express c-fos from the H2-Kb promoter in several organs. These H2-c-fos mice have enlarged spleens and hyperplastic thymuses containing an increased number of thymic epithelial cells. The exogenous c-fos expression specifically affects T cell development in the thymus, thereby increasing the fraction of mature thymocytes. Results obtained with bone marrow radiation chimeras suggest that the altered distribution of T cell subsets is not a direct effect of c-fos expression within the T cell lineage. No changes in the proportion of hematopoietic cell lineages are seen in the spleen, and these mice do not develop lymphoid malignancies. B and T cell function, however, is impaired, and H2-c-fos mice are immune deficient. It appears that c-fos specifically stimulates the proliferation of thymic epithelial cells, and may thus indirectly affect T cell development.

Animals↗
PubMed1988

[Chromatographic separation of mono- and oligomeric carbohydrates from biological materials with the use of HPLC glass columns].

By means of HPLC mono- and oligomeric carbohydrates are separated on silica, modified chemically with aminopropyl groups or impregnated in situ with an amine modifier (piperazine). Fundamentals of this sugar analysis are self-packed glass columns. The advantages of these columns are high efficiencies and handy column plugs. They are chemically inert and can be packed in different length with different HPLC packings. Applications of HPLC technique using glass columns are demonstrated by way of qualitative and quantitative determinations of carbohydrates in different food-stuffs and in polysaccharides (e.g. starch, regenerated fibre), hydrolyzed under acid and enzymatic conditions.

Carbohydrates↗
PubMed1988

Carbachol effects on hippocampal neurons in vitro: dependence on the rate of rise of carbachol tissue concentration.

Nominally K-sensitive microelectrodes were used to measure carbachol (CCh) in order to study the dependence of muscarinic effects on CCh concentration and exposure time in guinea pig hippocampal slices. Interference presumably originating from tissue choline-compounds was neutralized by pre-equilibration of the slices with 500 microM choline and calibration of the CCh-sensitive microelectrodes in the presence of the same choline-concentration. Muscarinic depolarization and reduction of the afterhyperpolarization (AHP) following a train of action potentials by bath applied CCh were monitored in granule cells and CA3 pyramidal neurons by intracellular recording. A fast bath application mode of CCh was designed, by which CCh tissue concentration reached a peak after 2-3 min and was washed out with a half time of about 8 min. After application of 30 nmol CCh in this way, the AHP was reduced according to the variation of CCh concentration over time. Neurons depolarized with some delay after the reduction of the AHP and started to repolarize 1 min before the peak of tissue CCh concentration (0.6 microM) was reached. Pirenzepine (1-10 microM) blocked only the depolarization, while atropine (1-10 microM) blocked both the depolarization and the reduction of the AHP. When superfusing with CCh containing saline, 80% of the final concentration was reached in the bath after 12 min, but in the tissue only after 45 min. The slow increase of tissue CCh concentration was concurrent with the slow decrease of the AHP. No effect on the membrane potential was observed. Atropine, but not pirenzepine, blocked the reduction of the AHP. Superfusion with a high CCh concentration (100-300 microM) containing saline depolarized neurons and reduced the AHP. Then pirenzepine repolarized neurons, whereas atropine both repolarized the cells and restored the AHP. It is concluded tha the muscarinic depolarization depends not only on the CCh concentration, but also on the rate of rise of CCh, while the reduction of the AHP depends solely on the concentration. This result is discussed in terms of the possibility that the depolarization is mediated by a short term desensitizing M1 muscarinic receptor subtype and the reduction of the AHP is mediated by a M2 muscarinic receptor subtype.

Animals↗
PubMed1988

The DiGeorge syndrome. I. Clinical evaluation and course of partial and complete forms of the syndrome.

This study describes clinical signs and symptoms in 16 patients with the DiGeorge syndrome (DGS). Diagnosed on the basis of typical facial stigmata, a broad spectrum of severity is seen with respect to congenital heart disease, hypoparathyroidism and immunologic parameters. A simple index of severity is introduced that clearly differentiates complete forms of the syndrome (cDGS) with poor prognosis from partial forms of the syndrome (pDGS). Of 13 pDGS patients, 12 are still living; 8 underwent corrective heart surgery without infectious complications. Moderate to severe mental retardation is seen in all pDGS patients. Due to the lack of thymus function, immunodeficiency is a result of cDGS, whereas immunoregulatory disturbances (hypergammaglobulinaemia, high titres of specific antibody production) prevail in pDGS patients.

Adolescent↗
PubMed1988

Erythropoiesis in chronic subdural haematomas.

In 41 out of 130 encapsulated chronic subdural haematomas erythroblasts were found. As there were no skull fractures and no erythroblasts were found in peripheral blood smears, it is concluded, that these colonies of erythroblasts originate from the granulation tissue during the formation of membranes. The actual output of mature erythrocytes is not known. The influence of erythroblasts on the clinical course of chronic subdural haematomas is uncertain.

Adolescent↗
PubMed1988

[Sonographic detection of fasciculations].

Fasciculations are an important neurological sign of spinal muscular atrophies. 26 patients able to walk suffering from adult onset spinal muscular atrophies were examined by real time sonography. On an average 18 limb and extremity muscles on both sides were examined. In 21 cases fasciculations became sonographically apparent as muscular twitchings lasting for 0.2 to 0.5 seconds. Detection of fasciculations in profound muscular layers and in obese patients was easier by sonography than by clinical examination.

Adult↗
PubMed1988

Detection of emotionally induced ECG changes and their behavioural correlates: a new method for ambulatory monitoring.

Heart rate is a well-established indicator of emotional arousal and can serve to detect emotional events. One difficulty, however, is in separating emotional heart rate increases from those increases due to physical activity. On-line analysis of both heart rate and physical activity (recorded with motion detectors) with a portable minicomputer may be able to solve this problem. We have developed a special algorithm that compares the values for heart rate and activity of a particular minute with the values of the previous minutes. If heart rate of a specific minute exceeds the rate of the previous minutes without an accompanying increase of activity, an emotional event may possibly be assumed. In such a case, the patient is requested by a beep signal to answer relevant questions about what he is doing, how he feels, etc. Moreover the patient is allowed to activate the system for himself for special events, e.g. chest pain. Methodological results of a first feasibility study with 32 cardiac patients are presented.

Affective Symptoms↗
PubMed1988

Porous hydroxyapatite and tricalcium phosphate cylinders with two different pore size ranges implanted in the cancellous bone of rabbits. A comparative histomorphometric and histologic study of bony ingrowth and implant substitution.

To investigate the histophysiology of implant degradation, hydroxyapatite and tricalcium phosphate cylinders with a diameter of 3 mm were implanted in the cancellous bone of the distal femur and the proximal tibia of 15 New Zealand White rabbits for up to six months. All implants had a homogeneous pore distribution and a porosity of 60%. Ceramics with a pore size range of 50-100 micron and 200-400 micron were compared. Morphometric analysis showed that up to 85.4% of the originally implanted tricalcium phosphate was degraded after six months, whereas the volume reduction of the hydroxyapatite was only 5.4% after the same period. Within the first months bone and tissue ingrowth and implant resorption occurred at a higher rate in the smaller-pored tricalcium phosphate than in the larger-pored material. Hydroxyapatite cylinders with small pores were totally infiltrated by bone or bone marrow after four months, whereas in the larger-pored hydroxyapatite implants tissue did not penetrate all pores after six months and the amount of bone within the implant was small. Scanning electron microscopy of the material before implantation revealed the existence of numerous pore interconnections with diameters of about 20 micron in the smaller-pored ceramics. Such interconnections were rare in the larger-pored implants. The pore interconnections seem to promote vascular and tissue ingrowth and consequently the initial rate of implant resorption. Implant resorption is an active process and involves two different cell types. Acid phosphatase-positive osteoclast-like cells suggesting active resorption adhere directly to the surface, especially in tricalcium phosphate implants. Clusters of macrophages tightly packed with granular material are found in the pores and along the perimeter of all implant cylinders. They may play an active role in the intracellular degradation of small detached ceramic particles.

Animals↗
PubMed1988

[The tenacity of bacteria in the airborne state. VI. Tenacity of airborne S. senftenberg].

The tenacity of airborne S. senftenberg 0:19 (heat resistant reference type W 775) was tested at different climatic conditions (21-40 degrees C and 15-85% relative humidity). The investigations were performed simultaneously in a static and a rotating aerosol chamber. The measured viability of the the germs was expressed as death rate beta biol and half life time t/2. The tenacity of the Salmonellae was highest at 85% humidity and 22 degrees C (optimum greater than 6 h t/2). Increasing temperature diminished the tenacity (minimum 6 min t/2 at 40 degrees C and 85% relative humidity). Low humidity also reduced the viability (maximum 53.7 min t/2 at 15% relative humidity and 28 degrees C. The results showed the same trend in the static and the rotating aerosol chamber. Therefore at standardized investigation modus a comparability of the measured values may be allowed. Because the airborne tenacity of the Salmonellae could be ascertained, the airborne route of transmission and infection has to be included into the epidemiology of the Salmonellae.

Air Microbiology↗
PubMed1988

[Systemic humoral immune response to food antigens following oral immunization or immunization via the respiratory tract].

Differences and similarities of the systemic humoral immune response to cow's milk proteins were investigated after exposure of the gut or of the airways to antigen, both in children and in rabbits. Circulating antibodies were determined by radioimmunoassay (children and rabbits) and by enzyme-linked immunosorbent-assay in a small number of children. An age-dependent reference range was established, reflecting the rapid change of active antibody formation after oral immunization against bovine serum albumin in healthy, non-breastfed children up to the age of 24 months (n = 181). In contrast 16 children with recurrent aspiration due to anatomical disturbances or swallowing difficulties, all had antibody-titers well above this reference range. 7 of 9 children with cow's milk protein intolerance and with failure to thrive (oral immunization) also showed high concentrations of milk antibodies in the circulation. In adult rabbits immunized by oral or inhalational route, the vigorous immune response seen in recurrent aspiration could be mimicked. As investigated by enzyme-linked immunosorbent assay, higher titers of antibodies to bovine serum albumin, alpha-lactalbumin, beta-lactoglobulin, alpha-casein and bovine gammaglobulin could be shown in all isotypes tested (specific anti-IgG, -IgA, and -IgE) both in recurrent aspiration (n = 11) and cow's milk protein intolerance (n = 4) as compared to normal age-matched children (n = 14).

Animals↗
PubMed1988

[The survival ability of pasteurella in the environment with special reference to the airborne situation].

This paper deals with so-called "indicator germs" in the air of stables, such as Micrococci, E. coli and Pasteurella species. It is pointed out, that mostly the sources of these germs are the animals themselves. Studying the sources of airborne bacteria our working group found a close correlation between applicated antibiotics (Chloramphenicol) and the resistance of airborne bacteria against this antibiotic. Spreading models lead to the conclusion that about 250-500 m around a stable there is a region of higher contamination by dust and infectious risk is increased.

Air Microbiology↗