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Biomedical subjects

K Schauenstein

Publications and source records attributed to K Schauenstein.

124 records · Page 7Linked to original sources
PubMed1980

Short time bleaching of fluorescein isothiocyanate. A possible parameter for the specific binding of conjugates in immunofluorescence.

The fluorescence kinetics of fluorescein isothiocyanate (FITC)-antibody conjugates during short (0.01 sec) laser excitations were analyzed for possible information about the immunological specificity of binding to antigenic substrates in direct immunofluorescence assays with antigen-coated Sephadex beads. First results of these investigations suggest marked differences in the bleaching characteristics of specifically and nonspecifically bound FITC conjugates: FITC-anti-bovine serum albumin (BSA) and FITC-anti-rabbit immunoglobulin (Ig) were found to fade significantly more slowly when bound to the respective homologous antigen (anti-BSA to BSA, and anti-rabbit Ig to rabbit Ig) as compared to nonspecifically adherent anti-BSA to rabbit Ig, and anti-rabbit Ig to BSA. Possible implications of these data for discrimination of nonspecific staining in immunofluorescence are discussed.

Antigens↗
PubMed1980

Quantitative immunohistochemistry.

In general there exist two possibilities to obtain quantitatively information in immunohistochemical work: (1) Titration of an antibody of defined specificity and concentration on different antigenic substrates. (2) The measurement of the "specific signal" of the marker molecule used for the visualization of the specific fixation of antibody to the homologous antigen in histological preparations. Examples for both kinds of approach are given by recent data from quantitative immunofluorescence (IF) studies performed in this laboratory. In the second part of this talk some theoretical aspects of quantitative IF are discussed concerning the fluorescence properties of fluorescein isothiocyanate, the most widely used fluorochrome. Macrospectrofluorometric measurements revealed marked effects on the emission intensity of the composition of the embedding medium and the concentration of the dye. Furthermore, the conjugation to protein is shown to cause a considerable quenching of UV excited fluorescence, but not at excitation with visible blue (496 nm). A further critical point in quantitative IF is the illumination source. The great advantages of laser light excitation as compared to filtered light of the most widely used mercury arcs are discussed. Finally some experimental data concerning the recovery of already faded fluorescence as observed with short, repeated laser light pulses are mentioned. The practical significance of these theoretical data are stressed.

Animals↗
PubMed1978

Fluorescence properties of free and protein bound fluorescein dyes. I. Macrospectrofluorometric measurements.

Excitation and emission properties of fluorescein derivatives were studied macrofluorometrically. Measurements were performed with solutions of various concentrations (0.07-100 microgram/ml) of free sodium fluorescein prepared from fluorescein diacetate (FDA), fluorescein isothiocyanate (FITC) and FITC bound to rabbit gamma-globulin. Both excitation and emission spectra as well as fluorescence intensities at constant excitation/emission wavelengths (496/515 nm) were recorded. The findings indicate that (1) FDA gives about twice the fluorescence intensity compared to equal concentrations of FITC. (2) The fluorescence properties of FITC upon excitation with blue light (lambda = 496 nm) are only slightly altered by the conjugation to rabbit gamma-globulin. (3) Considerable quenching due to conjugation could, however, be shown to occur upon UV excitation (lambda = 340 nm). (4) Fluorescence emission excited by visible blue light (496 nm) increases linearly to dye concentration in a range of 0.07-2.5 microgram/ml. Beginning at 5 microgram/ml (10-(5) M/1) all three compounds show a sharp decrease of fluorescence intensity with further increasing concentration. Practical aspects of these data for the immunofluorescence method are discussed.

Animals↗
PubMed1977

A new rapid modification for membrane fluorescence tests based on the Microtiter system.

This paper describes the micro-membrane-fluorescence test (MMF), which is a new semiautomated technique employing units of the Microtiter system. This method allowing the performance of several hundred samples within a few hours may contribute to further standardization of immunofluorescence work on the cellular level. Furthermore, it can also be applied in immunofluorescence tests were antigen coated particles (beads) are used as antigenic substrate, instead of living cells.

Antigens↗
PubMed1976

The micro-membrane-fluorescence test: a new semiautomated technique based on the microtiter system.

A semiautomated modification of the membrane immunofluorescence (MF) technique was developed employing units of the Microtiter system. This new rapid technique, which allows the performance of several hundred samples within a few hours is exemplified on a MF test proving the specific reaction to anti-chicken bursa cell sera (ABS) and antichicken thymus cell sera (ATS) on bursa and thymus cells respectively. The possible value of the new method for the further standardization of immunofluorescence is also emphasized.

Animals↗
PubMed1976

Antigenic relationship between chicken brain and granulocytes.

Antisera prepared in rabbits and turkeys against chicken brain were tested in membrane immunofluorescence and lymphocytotoxicity tests for their reactivity with thymocytes and cells from the bursa of Fabricius of normal White Leghorn chickens. In contrast to the findings in mice and other mammals, these antisera did not afford any specific reaction with thymus cells after exhaustive absorptions of species specific antibodies with cells from various tissues. However, absorbed rabbit antisera could be shown to react specifically with cells from the granulocytic series in the bone marrow and, to a lesser extent, in the peripheral blood of chickens.

Animals↗
PubMed1975

The nature of active and passive thyroglobulin binding lymphoid cells in Obese strain (OS) chickens.

Thyroglobulin-binding lymphoid cells were identified in the spleen of Obese strain (DS) chickens by their capacity to form rosettes with thyroglobulin-coated chicken red blood cells. The nature of these cells was studied in inhibition experiments using turkey anti-chicken bursa or thymus cell sera and rabbit antisera specific for chicken Ig, gamma, mu, alpha, Fabgamma or Fcgamma. Spleen cells actively synthesizing surface receptors for thyroglobulin were identified as B cells and the receptors found to be complete IgM molecules. Normal T cells became thyroglobulin-rosette-forming cells via passive adsorption of thyroglobulin antibodies, a phenomenon which could be inhibited competitively by the addition of normal chicken serum to the incubation medium. Thyroglobulin antibodies passively adsorbed onto the surface of normal T cells also belong to the IgM class as verified both by inhibition experiments and studies employing IgM and IgG fractions of a high titered OS serum for the preincubation of the cell suspensions. Only preincubation with the IgM fraction of the anti-thyroglobulin antibodies resulted in the formation of significant numbers of passive rosette-forming cells.

Animals↗
PubMed1975

Investigation of the recovery phenomenon in immunofluorescence after laser excitation.

Laser excitation was applied in two standard immunopathological indirect immunoflorescence systems in order to investigate bleaching and recovery of fluorescence intensity upon repeated illuminations. Variation of illumination times and dark periods between these showed that the recovery phenomenon is a function of both the (time times energy) product of excitation and the length of dark intervals. The value of high energy excitation in immunofluorescence in providing insight into the mechanisms of bleaching and recovery is discussed.

Antibodies, Antinuclear↗
PubMedDate not supplied

Regulatory effects of thymus humoral factor on T cell growth factor in aging mice.

The effect of thymus humoral factor (THF) on T cell growth factor (TCGF) production by T cells and the association between splenic macrophages and T cells from young (2-3 months) and old (20-24 months) mice in this respect were studied. Splenocytes were divided into three groups: stimulated with concanavalin A (Con A); preincubated with THF and then stimulated with Con A; or stimulated with Con A and thereafter incubated with THF. These cells were then examined for production of TCGF. Cells treated with Con A and THF as described above were passed on nylon wool to enrich T cell populations and added to mitogen-sensitized (Con A or lipopolysaccharide) adherent splenocytes of old and young mice in the following combinations: young adherent and young T cells; young adherent and old T cells; old adherent and young T cells; and old adherent and old T cells. The results demonstrated that: (A) cells of old mice produced less TCGF than the young; (B) preincubation of splenocytes or nylon-wool enriched T cells with THF increased the production of TCGF consistently in young mice, whereas in the old a significant increase was observed only in some cases; (C) depressed TCGF activity was observed when treatment with THF to splenocytes or nylon-wool enriched T cells from young and old mice was performed after Con A stimulation, and this was also more pronounced in the young; (D) the reduced level of TCGF in the old seemed to be related to a lesion in the T cell compartment, since adherent cells from old and young mouse spleens could support TCGF production by T cells from young mice and not from old.

Aging↗
PubMedDate not supplied

A possible role for acetylcholine in the dialogue between thymocytes and thymic stroma.

In this article we will review data suggesting that acetylcholine takes part in the mutual interplay between developing T cells and thymic epithelium, and thereby may influence the generation of the T-cell repertoire. In the first part we will recapitulate our findings according to which cholinergic agonists affect thymocyte apoptosis via a nicotinergic effect on thymic epithelial cells. In the second part we will present evidence that acetylcholine within the thymus is mainly derived from the thymocytes themselves, and that the production and release of this neurotransmitter is dependent on activation of thymic lymphocytes.

Acetylcholine↗