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Biomedical subjects

M Blank

Publications and source records attributed to M Blank.

At least 253 records · Page 14Linked to original sources
PubMed1982

Immunoregulatory mechanisms in pregnancy. 1. Evidence for the alpha-fetoprotein-induced generation of suppressor cells in vitro.

The generation of active suppressor cells has been induced in vitro by preculturing of splenocytes from normal mice in the presence of mouse amniotic fluid (MAF) and alpha-fetoprotein (AFP). By using freshly explanted splenocytes, addition of such precultured lymphocytes abrogated the generation of specific cytotoxic lymphocytes (CTL) in primary mixed lymphocyte cultures. Effective suppression can be induced only when the precultured cells are added within the first 48 hr of culture. These suppressor cells are nylon-wool nonadherent and their effect could be almost abolished by treatment with anti-Thy-1,2 serum plus complement. The precursors of the suppressor cells are sensitive to hydrocortisone and resistant to low doses of radiation. The induction of suppressor cells by AFP may be one of the mechanisms resulting in deviant immune response during pregnancy and in the newborn.

Animals↗
PubMed1981

Photoregulated ion binding.

A photoregulated chelating agent has been synthesized. It is a photochromic azobenzene compound containing two iminodiacetic acid groups and can exists as cis and trans stereoisomers. The planar trans isomer does not bind zinc ions. On exposure to light of 320 nanometers, the trans isomer is converted to a nonplanar cis isomer, which, because of cooperativity between the two iminodiacetic acid groups, binds zinc ions with the value of the binding constant estimated to be 1.1 x 10(5) +/- 9.2 x 10(5) liters per mole at a ratio of one molecule of chelating agent to one zinc ion. The interconversion of the cis and trans isomers is reversible, suggesting possible application of this class of compounds as photoresponsive ion pumps.

Chelating Agents↗
PubMed1981

Intraepithelial blood vessels in the vomeronasal neuroepithelium of the rat. A light and electron microscopic study.

Epithelial-vascular relationships are established during the development of the vomeronasal neuroepithelium of the rat. Special attention is given to the fine structure of the endothelial wall of intra-epithelial vessels, to ultrastructural aspects of the neuronal-vascular relationships, and to the appearance of inclusion bodies in the neuronal cells adjacent to these vessels. The neuronal perikarya surrounding the blood vessels are filled with highly developed smooth endoplasmic reticulum. Possible functional implications of the vascularization of the neuroepithelium of the vomeronasal organ in mediating olfacto-endocrine relationship are discussed. It is suggested that the intra-epithelial blood vessels are at least supportive and nutritive in nature, while their implication in an olfacto-endocrine connection remains obscure.

Animals↗
PubMed1981

Renal damage following transplantations of heterologous placental tissue.

Immunological interrelations between placenta and kidney have become a matter of interest with regard to the pathogenesis of preeclampsia. Kidney morphology of Lewis rats was studied following repeated transplantations of heterologous or syngeneic placental tissue. In most of the heterologous placenta-recipient animals, diffuse severe glomerular lesions were found, similar to those seen in women with preeclampsia. In the strongly responding recipients, endothelial cell swelling, narrowing of capillary lumina and proliferation of mesangial matrix were observed. Patchy areas of fluorescence associated with dense IgG deposition, as well as fibrin deposits demonstrated in the affected glomeruli, were correlated with histologic changes. The use of syngeneic placenta as a transplant did not cause histological or immunohistological changes. These findings support the view that differences in histocompatibility antigens between mother and fetus may be involved in the pathogenesis of the nephropathy in preeclampsia.

Animals↗
PubMed1979

Erythrocyte membrane proteins: a modified Gorter-Grendel experiment.

The pressure-area isotherm and shear resistance of spectrin-actin monolayers indicate a close-packed structure at about 1.0 m2/mg protein. This surface area is equivalent to a thickness of about two monolayers at the erythrocyte membrane inner face. The maximum elasticity (lowest compressibility) occurs at 0.7 mg2/mg protein, indicating the limit of reversible compression. The mechanical properties of the monolayers approximate those of the intact membrane, suggesting that the structures are similar and that these monolayers may account for many of the in vivo properties.

Actins↗
PubMed1978

[Laser surgery of the vocal cord. Clinical investigations with a view to treating small circumscribed carcinomas of the larynx (author's transl)].

It is reported on endolaryngel laser irradiation prior to operation, carried out, with varied dosage, on tumour-free areas of vocal cords of patients with larynx carcinoma. In these instances, the Nd:YAG-Laser MediLas (Messrs. MBB) with flexible light delivery, which we already used in earlier tests, was, for the first time, furnished with a laser endoscope--a special construction by Messrs. Karl Storz, Tuttlingen. The alterations caused on the vocal cords were investigated endoscopically and morphologically. It was proved that a laser induced lesion at a high dosage (55 W over 6 sec or 9 sec resp.) is capable to lead to a destruction of a carcinoma infiltrating into the vocal cord body.

Humans↗
PubMed1977

In vitro anti-kidney effect of lymphocytes in experimental immunization to placental antigens.

The lymph node and spleen lymphocytes of placenta-sensitized guinea pigs were tested for their ability to destroy kidney monolayer. It was shown by microcytotoxicity assay that these sensitized lymphoid cells killed target monolayer at different effector/target cell ratios. About 35% of kidney cells were destroyed when sensitized lymph node cells were added at a ratio of 500: 1, and 50% at a ratio of 1000:1. Immunized spleen cells produced approximately the same results. No significant cytotoxicity was measured when placenta-sensitized lymphocytes were added to nonrelated mouse skin fibroblasts. In order to exclude the possibility of participation of species-specific antigens in this experimental model, placenta-sensitized lymphocytes were added to L-cell monolayer in the presence of kidney antigens or mouse normal serum (a carrier of species-specific determinants). An extensive cytotoxic effect was observed in the presence of kidney antigens, while addition of mouse normal serum did not induce significant target cell lysis. The cross-reactivity of the cytotoxic ability of placenta-sensitized lymphocytes may indicate that cell-mediated immunity can be involved in the pathogenesis of nephropathy in toxaemic pregnancies, accompanying sensitization by placental antigens.

Animals↗
PubMed1976

Adsorption of albumin on rabbit sperm membranes.

When mammalian sperm cells are exposed to solutions of albumin there are changes in the membranes of some species that resemble those that normally occur in the uterus prior to fertilization. We have shown that albumin molecules absorb on to the membranes of ejaculated rabbit sperm cells, and that the equilibrium binding constant, K, (1) varies inversely with the albumin concentration, (2) is independent of the sperm cell concentration in the range of 10(6)--10(7) per ml, (3) is independent of the time of exposure of the sperm cells to the albumin solution, and (4) decreases in the presence of Ca++ and Mg++ ions. An unusual aspect of the adsorption is that if the albumin concentration is given the symbol [A], K[A] is a constant in our measurements. This means that for virtually the entire range of [A] studied, the sperm cells bind albumin so that half of the available surface is coated and half remains uncoated. This situation is rather remarkable and it suggests a role that adsorption could play in the physical processes preceding fertilization. In purely physical systems, the optimum for the bridging and flocculation of particles that are coated with adsorbed macromolecular films occurs when half of the available surface is covered. The sperm cell appears to provide the optimal situation for interacting with itself or with another surface.

Adsorption↗
PubMed1976

The effect of cholesterol on the viscosity of protein-lipid monolayers.

The addition of cholesterol to a layer of lipids in a membrane structure is generally believed to result in an increase in the viscosity of the layer. We have shown that cholesterol and two other monolayer-forming lipids markedly decrease the viscosity of a serum albumin monolayer at the decane-water interface, a model membrane system. However, when the protein monolayer already has a surface active lipid component present, the effect of added cholesterol depends upon the other substance. When the albumin monolayer contains tristearin, added cholesterol increases the viscosity. When the lipid is octadecanol, cholesterol decreases the viscosity. The dependence of the change in interfacial viscosity due to cholesterol upon the original composition of the interfacial layer may be useful for characterizing the composition of layers of unknown composition, e.g. some natural membranes.

Cholesterol↗