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Biomedical subjects

H Rink

Publications and source records attributed to H Rink.

At least 73 records · Page 4Linked to original sources
PubMed1982

Immunological properties of rat lens gamma-crystallins. I. Characterization of the major components.

Rat lens gamma-crystallins were separated by preparative flat bed isoelectric focusing (pH 7-11). The fractions obtained were submitted to analytical isoelectric focusing, fused rocket immunoelectrophoresis and immunodiffusion. The results demonstrate that rat lens gamma-crystallins are electrophoretically and immunologically heterogenous. Evidence is given that there are two immunologically different groups. Rat gamma 1-crystallin, the prominent and immunologically homogeneous part, is identical to calf lens gamma-crystallin. The second group of proteins, gamma 2-crystallins, is heterogeneous and shows only partial identity with gamma 1-crystallin.

Animals↗
PubMed1982

Immunological properties of rat lens gamma-crystallins. II. Characterization of low molecular weight components.

Two low molecular weight proteins with isoelectric points above pH 8 occur in the water-soluble proteins of the 24-day-old rat lens. Their molecular weights, estimated by SDS gel electrophoresis, are 9,500 and 10,500 daltons. The 9,500-dalton protein cross-reacts with gamma 1-crystallin. The 10,500-dalton protein designated gamma 3-crystallin is nonidentical with gamma 1 and gamma 2-crystallins and shows no cross-reactivity with alpha- and beta-crystallins.

Animals↗
PubMed1981

Investigations on the influence of whole body X-irradiation on the activity of rat lens aldose reductase (E.C. 1.1.1.21).

The influence of whole body X-irradiation on the activity of the enzyme aldose reductase (E.C. 1.1.1.21) in the lenses of young rats was investigated. Immediately after irradiation there was no difference between the activity of the enzyme in irradiated and nonirradiated animals. Within 10 days after irradiation, significant differences developed. There was a constant increase of the activity in the control lenses, while the activity in the irradiated lenses remained nearly constant. There was no remarkable difference between the two groups 10 days after irradiation with respect to the kinetics of the enzyme. This meant that irradiation does not affect the enzyme present at the moment of application, but the influence of 440 rad X-irradiation effects an obvious decrease in the synthesis of the enzyme.

Aldehyde Reductase↗
PubMed1980

Central actions of somatostatin.

Somatostatin (SRIF) was applied microiontophoretically to neurons in the frontal and parietal neocortex, the hippocampus and the striatum of rats anaesthetized with either urethane or chloral hydrate. Qualitatively identical results were obtained under both anaesthetic conditions. In urethane-treated rats SRIF elicited a dose-dependent increase of the firing rate of 74% of the neurons studied in the frontal cortex and of 46% of the neurons studied in the parietal cortex. All cortical cells identified as pyramidal cells were excited. In the hippocampus SRIF provoked excitatory responses in two thirds of all neurons. Six out of the nine cells identified as pyramidal cells were excited by SRIF. In the striatum 80% of all neurons were excited. Following repeated exposure of central neurons to SRIF, the magnitude of the excitatory response gradually diminished, indicating desensitisation. SRIF in concentrations ranging from 10(-8) to 10(-4) M did not interfere with the binding of (3H)-muscimol to GABA receptor sites. The release of GABA from synapses preloaded with (3H-GABA) was not influenced by SRIF in the concentration range from 10(-6) to 10(-4) M. These results indicated that SRIF does not evoke the excitatory responses through attenuation of GABA-mediated inhibition. In conclusion, the findings support the hypothesis that somatostatin may function as a neurotransmitter in the central nervous system.

Action Potentials↗
PubMed1980

Rat lens epithelial cells in vitro. I. Observations on aging, differentiation and culture alterations.

Lens epithelial cells from rats aged 5 days were grown in long-term cultures. These cells age, differentiate and transform spontaneously. Morphological observations indicate five different stages (A-E). The epithelial character is lost after the first two passages. Elongated cells appearing afterwards are considered as cells that have started differentiation to fiberlike cells. Big flattened cells are considered as senescent cells that have lost theie proliferative capacity. Data from population kinetics also reflect these five stages. Chromosome analysis shows that three of the five stages are no longer diploid. Two alternative modes of spontaneous transformation are possible. The proliferative capacity of rat lens epithelial cells is higher than that of rat embryonic fibroblast systems.

Aging↗
PubMed1980

Rat lens epithelial cells in vitro. II. Changes of protein patterns during aging and transformation.

Serially subcultured rat lens epithelial cells grow in different stages, which can be classified according to morphology, chromosome numbers and population kinetics. A lens-specific gamma-crystallin appears in the diploid stage, when elongated cell types are observed. One of the beta-crystallin bands (pH 5.7) disappears during aging in higher passage numbers of the diploid stage B. A weak band in the beta-crystallin region (pH 6.4), which is present in all stages, becomes very intensive in aneuploid cells of stage D, which exhibit a fibroblast-like morphology.

Animals↗
PubMed1979

Non-selective inhibition of basal glucagon release by [D-Cys14]-analogues of somatostatin in the rat.

The effects of two [D-Cys14]-analogues of somatostatin on basal plasma levels of glucagon, insulin and glucose were determined in unanaesthetized rats to re-examine a glucagon-selective action of these peptides which has been claimed by others. Somatostatin, [D-Cys14]-somatostatin and [D-Trp8, D-Cys14]-somatostatin caused a short-lasting, dose-dependent decrease of plasma glucagon and insulin but they had no significant influence on plasma glucose. Glucagon and insulin reached the nadir 2 min after intravenous injection of the peptides (dose range 1--10 micrograms/kg) or 5 min after subcutaneous administration (30 and 300 micrograms/kg). At the nadir, insulin was decreased to a greater extent than glucagon and the effecer the nadir and at high doses, the time-course of some effects of the analogues on either glucagon or insulin differed from that of somatostatin. Thus, these [D-Cys14]-analogues may show partial kinetic dissociation of effects on glucagon and insulin but they are not truly selective inhibitors of glucagon release.

Animals↗
PubMed1977

[Influence of radiation-induced electrolytic shifts upon the metabolism: VII. On the question of equivalence of K+-loss and Na+-uptake (author's transl)].

Irradiated and nonirradiated yeast cells in three different metabolic conditions were incubated with four different culture mediums at various K+/Na+-concentrations and with or without glucose. The losses of K+ and the incorporation of Na+ are analysed after five hours and represented as balance values. Equivalent shifts appear in metabolic stagnation but not with metabolizing cells. The balance values nevertheless are equal in irradiated and in nonirradiated samples. This means that the radiation-induced additional exchange always is equivalent. This finding indicates a membranous modification as cause of radiation-induced electrolytic shifts.

Potassium↗
PubMed1975

Giant cells from Saccharomyces uvarum grown after x-irradiation.

Yeast cells, Saccharomyces uvarum, were irradiated with X-rays and grown in liquid suspension. Glucose as the only carbon source was limited to 12.5 mM. Under these conditions giant cells are formed. Cell number, glucose utilization, ethanol production and oxygen consumption are measured during the time of growth. The mean weight of single cells in the stationary phase increases up to 75 krad and is not due to an uptake of water. In irradiated cultures oxygen consumption and glucose utilization per cell are higher than in control cells. The data demonstrate that synthesis- and energy-metabolism during the formation of non-dividing, radiation-induced giant cells is increased.

Ethanol↗