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Biomedical subjects

K Hannig

Publications and source records attributed to K Hannig.

At least 37 records · Page 2Linked to original sources
PubMed1980

Recognition of a positive MLC reaction after four hours.

EMT indicator cells were incubated for 1 h in the supernatant of a 3 h MLC. Their electrophoretic mobility was then measured by an analytical, carrier-free electrophoresis system. The alteration of their mobility against a medium-standard was calculated in per cent and correlated with the conventional measured MLR-cpm. According to our results the correlation of the two quantities is statistically highly significant. This method could enable recognition of a positive or negative MLC after only 4 h. This fact could be of great importance for histocompatibility testing and transplantation.

Cell Movement↗
PubMed1980

Radio-iodinated surface proteins of electrophoretically separated rat lymphocytes.

Rat thymocytes and lymph node cells were separated into three T and one B subpopulation by means of free flow electrophoresis. The surface proteins of the separated cells were labeled by lactoperoxidase catalysed radioiodination. Most of the label was demonstrated to be at the cell surface. The labelled cells were either lysed in sodium dodecyl sulphate or treated with Nonidet P-40 to extract cell proteins. The radioiodinated proteins were analysed on sodium dodecyl sulphate polyacrylamide gel electrophoresis followed by autoradiography. In contrast to sodium dodecyl sulphate Nonidet P-40 did not extract cell proteins completely. Furthermore the degree of extraction varied considerably in the different cell populations. 58% of protein bound radioactivity was extracted from thymocytes, 67% from peripheral T cells and 81% from B cells. Gel electrophoresis revealed that four proteins were not extracted at all, whereas five components were better soluble in Nonidet P-40 than all other proteins. One protein was extracted from B cells only although it was present in all cells. Although the surface protein patterns of the four lymphocyte subpopulations were rather similar, distinctive differences could be found. B cells had six labelled proteins which seemed to be absent in the other cells, In the T cell group, three protein bands were identified, each with specificity for peripheral T cells, thymocytes and all T cells respectively. Four other proteins were found which showed quantitative differences between the four cell groups.

Animals↗
PubMed1979

Cytofluorometric analysis of R-Thy-1. antigens in various rat lymphocytes with different electrophoretic mobility and organ distribution.

Small bone marrow lymphocytes, which had been previously enriched by velocity sedimentation, thymocytes, lymph node cells and spleen cells were electrophoretically separated, stained with fluorescein conjugated rabbit a-rat-Thy-1. globulin and their fluorescence intensities analyzed with a flow cytophotometer. Thy-1. antigens were found in 80% of the bone marrow small lymphocytes showing low electrophoretic mobility (EPM), in all thymocytes, about 80% of which show low and the rest medium to high EPM, and in a few lymph node cells of high EPM. Thy-1. positive cells were not observed in the spleen. All fluorescence intensity histograms obtained were modal and could be properly fitted with normal curves showing coefficients of variation (C.V.) in the range of 20% to 30%. It was observed that the thymocytes of low EPM had an antibody binding affinity significantly different from that of the other stained lymphocytes. Moreover the surface antigen density decreased in the sequence: thymocytes of low EPM, bone marrow lymphocytes of low EPM and thymocytes of high EPM. The fluorescence intensity of stained lymph node cells of high EPM appeared similar to that of thymocytes of high EPM but was not evaluated precisely. Thus the two dimensional cell analysis provided by a combination of EPM and surface fluorescence of Thy-1.+ cells, allows the characterization of different lymphocyte populations which cannot be clearly identified with normal one dimensional techniques. The biological significance of the results is discussed briefly.

Animals↗
PubMed1977

Free-flow electrophoresis. III. An analytical version for a rapid, quantitative determination of electrophoretic parameters.

An analytical device based on the principle of free-flow electrophoresis is described. Electrophoretic mobility distributions of proteins or cells can be obtained quickly with field-strengths of about 140 V/cm. Up to 100 samples can be tested per hour. The accuracy and reproducibility of the device is illustrated by the example of the serum protein separation. Quantities in the picomole range can be quantitatively evaluated. In the course of mobility measurements of cells and cell mixtures, a reproducibility of +/- 1.4% was obtained. Therefore this device meets both the needs of electrokinetic research and the requirement of routine measurements in clinical diagnosis. Finally, the application of a pH gradient is described and the limitation due to methodical aspects is shown.

Animals↗
PubMed1976

B lymphocyte subpopulations in the mouse spleen. A study of the differentiation pathway using free flow electrophoretically separated subpopulations of direct PFC progenitor cells.

Free-flow electrophoretic separation of mouse spleen cells provides three distinct progenitor cells of direct PFC, showing high, medium and low electrophoretic mobility. All progenitor cells possess surface immunoglobulin and mouse B-lymphocyte specific antigen. The progenitor cells of high electrophoretic mobility show high cycling turnover, a spleen seeking capacity of 16%, provide PFC with a maximum 8 days after transfer and reveal an isometrical increase of the PFC dose response line as a function of the graft size. The progenitor cells of medium electrophoretic mobility are low cycling, 16% home to the spleen, a maximum of PFC is developed eight days after transfer and the PFC dose response line increases allometrically. The progenitor cells of low EPM show low cycling activity, 20% home to the spleen, a maximum of PFC is attained six days after transfer and the PFC dose response line rises isometrically. These results suggest that the electrokinetically different PFC progenitors represent biologically distinct subsets. In double transfer experiments, some evidence was obtained that progenitor cells of low electrophoretic mobility are derived from progenitors of higher electrophoretic mobility. The same observation accounts also for the formation of B lymphocytes of low EPM. Since it seemed likely that the PFC progenitor cells represent virgin cells of a single lineage, the results were discussed in the terms of differentiation pathways of B lymphocytes. A model is considered in which a progenitor of medium electrophoretic mobility provides those of high electrophoretic mobility which after passing a transient cycling stage finally produce mature resting B lymphocytes of low electrophoretic mobility.

Animals↗
PubMed1975

[Free-flow electrophoresis. I. Theoretical and experimental investigations of the influence of mechanical and electrokinetic variables on the efficiency of the method].

In the present paper, various types of band-broadening effects in free-flow electrophoresis were investigated. They resulted from the velocity profiles of the liquid curtain and electroosmosis, temperature gradient, thermal diffusion and sample inlet geometry. An analytical free-flow electrophoresis apparatus permitted easy observation of these parameters. The experiments showed that the influence of the temperature gradient was negligible, whereas the effect of the velocity profiles on band broadening was higher than theoretically expected. In preparative work this is of utmost importance, since overlap of bands is not desirable. In this case, the zeta potential of the walls can be adjusted to that of the material to be separated, resulting in a considerable reduction of band broadening. Various approaches are indicated. Further attention was given to the influence of the relaxation effect on the separation. Conditions are shown where particles are separated either according to their surface charge density or to their size. The practical relevance of the results is discussed.

Electrophoresis↗
PubMed1975

Free-flow electrophoresis. II. Analysis of the method with respect to preparative cell separation.

Electrophoretic cell separation by means of free-flow electrophoresis in an FF5 apparatus was investigated with respect to band resolution, separation capacity, reproducibility and influence on cell viability. Very sharp bands and a large separation capacity were achieved using triethanolamine/acetate buffered glycine media as liquid curtain. Acid buffer ions such as N-2-hydroxyethylpiperazine-N'-ethanesulfonic acid (HEPES) or phosphate produced broader bands. Osmotic expanders such as saccharides, though preserving cell viability excellently, decrease electrophoretic velocity and thus separation capacity. The decrease in cell viability observed in glycine media could be compensated for by addition of Ca2. Band broadening caused by methodologically specific velocity flow profiles could be reduced to a negligible level by coating the chamber walls with albumin and by appropriate adjustment of sample flow rate and liquid curtain velocity. Under the optimum conditions described, selective cell loss and artificial change in electrophoretic mobility of the cells during operation can be disregarded. The main reason for cell loss was cell aggregation at low ionic strength, which can be prevented or reversed by treatment of the cells with deoxyribonuclease.

Animals↗
PubMed1974

Deoxyribonucleic acid-envelope complexes isolated from Escherichia coli by free-flow electrophoresis: biochemical and electron microscope characterization.

A procedure for the preparative isolation of Escherichia coli cell wall, membrane, and deoxyribonucleic acid (DNA)-envelope complex fragments has been developed. The envelope fragments were produced by controlled mechanical cell breakage and isolated by density gradient centrifugation and subsequent preparative free-flow electrophoresis. The DNA-envelope complex fragments were shown to contain biochemical markers of both the cell wall and the membrane and by electron microscopy to be cell envelope fragments containing wall/membrane adhesion zones.

Amino Acids↗
PubMed1972

The polarity of the proximal tubule cell in rat kidney. Different surface charges for the brush-border microvilli and plasma membranes from the basal infoldings.

Two different membrane fractions were obtained from a brush-border fraction of rat kidney cortex by using their different electrical surface charges in preparative free-flow electrophoresis. One membrane fraction contained only morphologically intact microvilli and was characterized by a high specific activity of alkaline phosphatase. The other fraction morphologically resembled classical plasma membranes by possessing junctional complexes and a high Na-K-ATPase activity The contamination of the isolated membrane fractions by other cell organelles was extremely low These two fractions represent the apical (luminal) and the basal (interstitial) area of the renal proximal tubule cell membrane and clearly demonstrate the polarity of this cell.

Adenosine Triphosphatases↗