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Biomedical subjects

E Neumann

Publications and source records attributed to E Neumann.

At least 145 records · Page 8Linked to original sources
PubMed1978

Asymmetric displacement currents in giant axons and macromolecular gating processes.

An electrical-chemical gating model is proposed that describes basic observations on asymmetric displacement currents and transient Na+ conductivity changes in squid giant axons. A previously developed single-parameter analysis of primary voltage clamp data yields normal mode relaxation times that agree well with the time constants of asymmetric capacitative currents, suggesting these currents as gating currents associated with charge displacement in a subunit of a complex gating system. The physical-chemical approach correlates the opening of Na+ channels with charge-charge interactions amongst displaceable membrane charges or dipoles and conformational changes in gating macromolecules. The model covers the close correspondence between the voltage dependence of the peak value of the Na+ conductance change and that of the square of the total displaced charge for small depolarizing voltage steps. The quadratic charge relationship also describes the two-mode relaxation of asymmetric displacement currents; the transiently inhibited return transition of two-thirds of the displaced charge after a prolonged depolarization is interpreted to reflect a dissipative chemical gating process.

Axons↗
PubMed1978

Intracutaneous herniation of fat in connection with microangiopathia diabetica.

Three women with diabetes mellitus presented an unusual change in the skin on the distal and acral parts of the extremities, most distinctly on the upper surface of the hands. The surface was raised in small cushions but had the colour of intact skin. The skin felt doughy and swolen on palpation but there was no oedematous pitting. It had been suspected earlier that these skin changes indicated myxoedema or heart disease and the patients had been treated with diuretics. In all three cases, however, histological examinations revealed a more or less reduced, atrophic dermis with here and there an appreciable dislocation of the subcutaneous layer of fat, which with the sweat glands formed an intracutaneous herniation up against the epidermis. These histological changes explained the clinical picture of cushions in the skin. As these patients had diabetes mellitus and the histological picture also included vascular changes of the type associated with a diabetic microangiopathy, it is considered that this form of intradermal herniation of fat is yet another skin change which may be elicited by diabetes mellitis.

Adipose Tissue↗
PubMed1978

The nature and role of epidermal regressive changes in the development of the psoriatic lesion.

Damaged epidermal cells present in psoriatic lesions were investigated using histochemical and histomorphological methods including ultrathick sections. In early lesions these cells were found throughout the epidermis, being particularly numerous in the upper part of the latter and around the adnexa. In a later developmental stage the damage to the keratinocytes in the suprapapillary region was found to precede the damage to the basement membrane. These findings, together with the difference between the damaged keratinocytes lining the ascending side and the venous limb of the papilla respectively with regard to degree of severity of the damage, suggest that blood stasis is the cause of the regressive changes in the suprapapillary epidermis. The enzymatic activity of non-specific esterases and acid phosphatases was increased and that of succindehydrogenases and DPN-diaphorase was decreased in damage keratinocytes. The significance of these findings in relation to the genesis and development of psoriasis is discussed. The view is expressed that there is a causal relationship between damage to the epidermal cells and proliferation of epidermis.

Acid Phosphatase↗
PubMed1977

[Polycythaemia as sole symptom of renal adenoma (author's transl)].

In two children, a 9 year-old boy and a 10 1/2 year-old girl, who presented with polycythaemia as the only symptom, the expected renal tumour was only found after exclusion of all other causes of polycythaemia. The delay in diagnosis was caused by technically inadequate intravenous urograms, which were erroneously passed as normal. In one child low kv X-ray exposition of the kidneys led to the diagnosis of a renal tumour. In the other child high-dose urography and tomography gave the indication for selective angiography. Normalization of the red blood count postoperatively verifies the connection between preoperative erythrocytosis and the renal tumour. Histologically both cases proved to be renal adenomas, which are extremely rare in childhood.

Adenoma↗
PubMed1977

Malate dehydrogenase isolated from extremely halophilic bacteria of the Dead Sea. 1. Purification and molecular characterization.

The complete purification of malate dehydrogenase (EC 1.1.1.37) from extremely halophilic bacteria of the Dead Sea is described. The purification procedure includes (a) precipitation by ammonium sulfate, (b) fractionation on Sepharose 4B using a decreasing concentration gradient of ammonium sulfate, (c) gel permeation chromatography on Sephadex G-100, (d) chromatography on hydroxylapatite, and (e) affinity chromatography on 8-(6-aminohexyl)amino-NAD+-Sepharose at 4.26 M NaCl. The absorption and fluorescence spectra of the native and denatured enzyme were measured, and the extinction coefficient at 280 nm in 4.26 M NaCl was found to be 0.803 cm2mg-1. The amino acid composition analysis showed an excess of 10.4 mol % of acidic amino acids. The apparent specific "volume" phi' of the active enzyme at 4.26 M NaCl was found to be 0.680 +/- 0.015 mL/g. The molecular weight of the native enzyme was found to be 84 000 +/- 4000 determined in 4.26 M NaCl from equilibrium sedimentation data. The molecular weight of the subunits is 39 000 as measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Thus, the native enzyme is composed of two subunits.

Amino Acids↗
PubMed1977

Kinetics of permeability changes induced by electric impulses in chromaffin granules.

Electric field pulses, ranging in intensity from 20 to 50 kV/cm and in duration from 10 to 40 micronsec, caused a transient increase in the membrane permeability of chromaffin granules from the bovine adrenal medulla, that led to partial release of granule soluble constituents. This transient permeability change was long-lived, as compared to the pulse duration, and the main part of material efflux occurred after the termination of the pulse. During the latter phase the temporarily increased permeability decayed to its original value, in the absence of the electric field. This indicated that the structural perturbation induced in the membrane was transient and apparently reversible. The release event was characterized by a field-dependent permeability coefficient ranging from 2x10(-4) cm/sec at 30 kV/cm to 3x10(-3) cm/sec at 50 kV/cm. The resealing process of the membrane could be described by two relaxation times, both of which decreased with increasing field strength. Tau1 varied from about 3.0 msec at 30 kV/cm to less than 2.0 msec at 50 kV/cm, while tau2 varied from about 100 to about 40 msec in the same interval of field strength. The distribution in the degree of filling of granules that had been partially depleted by an electric field pulse indicated that the population could be considered homogeneous with respect to release.

Adrenal Medulla↗
PubMed1977

"VA", a new type of erythrocyte polyagglutination characterized by depressed H receptors and associated with hemolytic anemia. I. Serological and hematological observations.

This report describes a case of persistent polyagglutinability restriced to the red blood cells, and associated with hemolytic anemia in a 20-year-old male. AIME WITH NORMAL INTERVALS. His red blood cells were weakly agglutinated by almost all adult sera. No autoagglutination was noted and the direct antihuman globulin test was negative. Polyagglutinability of his red blood cells was clearly distinguishable from T, Tn and Tk. No reaction was noted with Dolichos biflorus and peanut extracts. The cells differed from normal erythrocytes in their positive reactions with various snail agglutinins and their weak reaction with a range of anti-H reagents. There was normal aggregation by Polybrene. MN determinants were normally expressed. The symbol "VA" is roposed for this type of polyagglutination.

Adult↗
PubMed1976

[Blocking and binding antibodies to intrinsic factor and their behaviour during oral therapy with intrinsic factor-vitamin B 12 complex (author's transl)].

13 patients with pernicious anaemia and 2 patients who had been subjected to total gastrectomy were treated orally with a hog instrinsic factor preparation (IF) for 1 to 4.5 years. During this therapy 11 of the patients with pernicious anaemia and both gastrectomized patients developed blocking and binding antibodies to IF. Antibodies already present before the commencement of therapy showed an increase in titre. All patients remained in complete haematological remission. The conclusion is drawn that circulating antibodies to IF do not play any significant role in the absorption of the hog IF-B 12 complex.

Administration, Oral↗