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Biomedical subjects

J Unger

Publications and source records attributed to J Unger.

At least 109 records · Page 6Linked to original sources
PubMed1982

Interference of serum tonicity with the measurement of red cell mean corpuscular volume.

When red cell mean corpuscular volume (MCV) is determined by use of the Coulter counter, the blood sample is first diluted in a solution with fixed osmolality (Isoton). Therefore we studied the interference of blood osmolality with MCV measured by this method. In 14 patients with hyposmolality, the correction of osmolality was accompanied by an increase in MCV of 4.7% (p less than 0.001) and a decrease in mean corpuscular hemoglobin concentration (MCHC) of 4.8% (p less than 0.001). In 9 patients with hyperosmolality the decrease in MCV was of 5% (p less than 0.001) and the rise in MCHC of 4% (p less than 0.001) after osmolality correction. Before correction of hyposmolality, 1 patient had false microcytosis and 3 had masked macrocytosis. In the hypertonic group 3 patients has initially false macrocytosis. Red blood cells (RBC) from hypotonic patients probably shrink when they are acutely placed in the Isoton which is a hypertonic solution (330 mosm/kg H2O). Conversely RBC from patients with severe hyperosmolality swell in the same conditions. The patients osmolality must be considered to interpret the MCV measured by the Coulter counter correctly, as a 10-mosm/kg H2O change in serum osmolality is responsible for an artefactual change in MCV of 1 fl.

Blood Physiological Phenomena↗
PubMed1981

[Importance of the cell membrane for the sequestration of aged erythrocytes].

The erythrocyte membrane is an important cell organelle which determines the intravital life time of the cell in a decisive way. Their mechanic properties are closely connected with the metabolism of the cells. Increasing disturbance of the cellular metabolism especially in the course of biological aging leads to enhanced cell rigidity. It is supposed that the decreased elasticity of the aged erythrocytes in critical regions of the blood circulation (capillaries with a diameter of 2.5 to 3.0 micrometers) leads to pressure induced vesiculation and spherocytosis. It is possible that also IgG-receptors are demarked by this process. After passing a threshold concentration as immunobiological signals increased irreversible binding of IgG induces the sequestration of the erythrocytes by the erythrocyte destructing system.

Animals↗
PubMed1981

Deformability of erythrocytes incubated at various pH-values.

The deformability of human erythrocytes was studied at pH values ranging from 6.4 to 8.5 using micropipette aspiration of whole cells. Also the mean cell volume was measured in dependence on pH. The observed high increase of the transit pressure pt with lowering of the pH in a fairly narrow interval suggests that within the range of pH values under consideration pi is mainly controlled by the effect of the critical volume of the cells.

Erythrocytes↗
PubMed1981

[Genesis of microcytes in hemodialysis patients with chronic uremia].

The study is concerned with factors that may reduce the life time of erythrocytes of patients under intermittent haemodialysis. The red cell population of these patients consisted of micro-, normo-, macro- and megalocytes. The classification of the cell size was shiftet to greater diameters in comparison with healthy donors. The evaluation of the biological half time of erythrocytes labelled with 51Cr resulted in a decrease of about 16 days. The autoradiographic evaluation of the erythrocyte size-distribution patterns 1 and 24 hours after the injection of labelled red cells into the donors circulation clearly demonstrated a decrease of macro- and megalocytes. Simultaneously, the number of microcytes rose considerably. The measurement of erythrocyte deformability could demonstrate a clearcut relationship of flexibility for a) disturbed erythropoiesis resulting in the production of macro- and megalocytes, and b) fragmentation and premature elimination from the circulation due to unfavourable rheologic properties of erythrocytes of abnormal big and small sizes.

Autoradiography↗
PubMed1980

Kinetics of benzo[a]pyrene induced mutagenesis in a highly sensitive salmonella/microsome assay.

The kinetics of benzo[a]pyrene induced mutagenesis in Salmonella typhimurium TA98 and TA100 were studied using a liquid-phase assay and were compared to kinetics of metabolism of benzo[a]pyrene in the same system. Mutagenesis was terminated by the addition of pyrene + menadione at selected times. Under conditions of the assay using hepatic microsomes from 3-methyl-cholanthrene pretreated rats, metabolism of benzo[a]pyrene was over 50% complete in 5 min, and metabolism of initial metabolites became appreciable after this time. The revertant frequency (revertants/10(8) survivors) and the production of tertiary metabolites increased sharply after 5 min and leveled off at 40 min.

Animals↗
PubMed1980

The role of calcium and guanosine 3':5'-monophosphate in the action of acetylcholine on thyroid metabolism.

The role of calcium and guanosine 3':5'-monophosphate (cyclic GMP) in the regulation of thyroid metabolism has been investigated in dog thyroid slices. Carbamoylcholine enhanced glucose carbon-1 oxidation, protein iodination, cyclic GMP accumulation and decreased thyrotropin-induced adenosine 3':5'-monophosphate (cyclic AMP) accumulation and iodine secretion; it did not affect protein synthesis. The effects of carbamoylcholine were reproduced under various experimental conditions by supplementary calcium in the medium, ouabain, and in media in which Na+ had been replaced by choline chloride. They were inhibited by lanthanum. These results further support the hypothesis that free intracellular Ca2+ is the intracellular signal for carbamoylcholine effects and suggest that a Na+ -gradient-driven Ca2+ extrusion mechanism operates in the thyroid cell. Mn2+ reproduced the effect of Ca2+ on glucose oxidation, protein iodination and cyclic GMP accumulation in Ca2+ -depleted slices and medium, and thus mimicked some intracellular effects of Ca2+. On the other hand Mn2+ inhibited the carbamoylcholine effect on thyrotropin-induced thyroid secretion and cyclic AMP accumulation, and Ca2+ inhibited the Mn2+-induced cyclic GMP accumulation. This suggests that the two ions compete for the same channel. Similarly Mn2+ inhibited calcium effects in the presence of ionophore A23187. Procaine inhibited protein iodination under all conditions suggesting a primary effect; it also inhibited all carbamoylcholine and ouabain actions. However the drug did not inhibit the effects of choline chloride and its action was reversed by raising carbamoylcholine but not Ca2+ concentration; it is therefore doubtful that procaine acts by blocking Ca2+ channels. In media without added Ca2+, Mn2+ increased cyclic GMP accumulation but did not decrease thyrotropin-induced cyclic AMP accumulation or iodine secretion, which suggests that cyclic GMP cannot be the sole mediator of the latter two effects of carbamoylcholine.

Acetylcholine↗
PubMed1980

Lithium in haematology: a case of acute intoxication.

A 74-year-old woman was treated by lithium carbonate 3 x 300 mg per day for drug-induced aplastic anemia. After 8 days, she suddenly developed severe impairment of consciousness with myoclonias and hypertonia which persisted during 10 days despite lithium withdrawal and sodium chloride infusion. Slight disorders of water and electrolyte metabolism, mild renal failure and the patient's age could have contributed to the development of intoxication. Short-term lithium administration may be life-threatening and should thus be prescribed cautiously in hematological disorders as in other conditions.

Aged↗
PubMed1980

In vitro regulation of ornithine decarboxylase in dog thyroid slices.

Ornithine decarboxylase (ODC) activity in dog thyroid slices incubated in vitro disappears when protein or RNA synthesis is inhibited. Thus, as in other tissues, the level of the enzyme reflects a balance between rapid synthesis and catabolism. TSH, dibutyryl cAMP, prostaglandin E1 (PGE1), and cholera toxin all stimulated dog thyroid ODC activity. These actions were potentiated by the inhibitor of phosphodiesterases, 4-(3-butoxy-4-methoxy-benzyl)2-imidazolidinone (Ro 20-1724), and reproduced by high concentrations of this inhibitor, while 1-methyl-3-isobutylxanthine inhibited ODC induction. Iodide blocked the action of TSH; this inhibition was relieved by methimazole. Calcium depletion or manganese addition depressed enzyme levels in control and stimulated tissue. In some cases (ionophore A23187 addition and calcium depletion), total protein synthesis was also depressed. Carbamylcholine and the ionophore A23187, which can raise cGMP in thyroid slices, inhibited TSH and dibutyryl cAMP induced ODC increases, PGF1 alpha was inhibitory to ODC stimulation. Indomethacin, which had no effect on TSH action, relieved carbamylcholine inhibition. These results show that dog thyroid ODC is stimulated by TSH through cAMP, and suggest that cholinergic stimulation of the tissue blocks TSH activation of the enzyme, possibly at a step beyond cAMP synthesis, by increasing PGF synthesis. The effect of carbamylcholine is not due to cGMP, since it can be obtained under conditions where basal cGMP levels are not increased.

1-Methyl-3-isobutylxanthine↗
PubMed1980

Thyroglobulin and thyroid hormone release after intravenous administration of bovine thyrotropin in man.

To elucidate the mechanism of thyroglobulin (Tg) release in man, the effects of an iv injection of a submaximal dose of bovine TSH (bTSH) on the serum levels of Tg were compared with the effects on serum T3 and T4. After the administration of bTSH, short term kinetics (0-4 h) were studied in eight subjects receiving 0.5 IU bTSH and seven subjects receiving 1 IU bTSH. Serum Tg did not significantly increase in either of the short term studies. By contrast, serum T3 increased significantly and linearly after the administration of 0.5 and 1 IU bTSH; serum T4 also rose but only after 1 IU bTSH. Long term kinetics (0-120 h) were studied in seven additional subjects after the iv administration of 1 IU bTSH; serum bTSH was no longer detectable after 8 h. Maximum serum concentrations of T3 were obtained at about 4 h, maximum serum concentrations of T4 were obtained between 4-8 h. Serum Tg levels increased linearly with time during the first 24 h. Maximum serum Tg levels correlated well with basal serum Tg values (r = 0.97; P < 0.001). The maximal increment in Tg correlated inversely with the maximal increment in T3 (r = 0.71; P < 0.05). The half-life of Tg was estimated to be approximately 4 days by measuring the disappearance rate of Tg after its peak level was attained.

Adult↗
PubMed1980

Alteration by procaine of spectrin cross-links, deformability, and fluidity related properties of the erythrocyte membrane.

The study on procainized human erythrocytes revealed a) temperature dependent changes of cellshapes, b) a significant increase of deformability, c) low amounts of cross-linked membrane proteins, d) a mean cell volume identical with the volume of nonprocainized cells, e) severe reduction of induced anisotropy, f) no loss of negatively charged groups of the glycocalyx, g) decrease of electrophoretic velocity, h) a significant rise of adhesiveness to glass, and i) increase of agglutinability with antiserum and lectin. The findings are discussed in their relationships to alterations of the molecular structure of the red cell membrane.

Adhesiveness↗