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Biomedical subjects

H Hartmann

Publications and source records attributed to H Hartmann.

At least 217 records · Page 12Linked to original sources

Conformational substates in a protein: structure and dynamics of metmyoglobin at 80 K.

The crystal structure of sperm whale metmyoglobin has been determined at 80 K to a resolution of 2A. The overall structure at 80 K is similar to that at 300 K except that the volume is smaller. Refinement of the structure by the method of restrained least squares (current R = 0.175) permits the assignment of isotropic atomic mean-square displacements to all nonhydrogen atoms. Comparison with the values obtained earlier at 250-300 K indicates that the protein at 80 K is more rigid. The average experimentally determined Debye-Waller factor, B, for the protein is 14A2 at 300 K and 5A2 at 80 K. Plots of backbone mean-square displacement vs. temperature show a discontinuity of slope for at least one-third of all residues. This behavior is in good agreement with the temperature dependence of the mean-square displacement of the heme iron as measured by Mössbauer absorption. The magnitudes of the smallest mean-square displacements observed at 80 K indicate that intramolecular motions can be frozen out to a surprisingly large degree. Even at 80 K, however, some atoms in myoglobin still have mean-square displacements greater than 0.1A2, thus providing evidence for conformational substates.

Animals↗

Direct control of glycogen metabolism in the perfused rat liver by the sympathetic innervation.

The mode of action of hepatic nerves on the metabolism of carbohydrates was studied in the rat liver perfused in situ. 1. Electrical stimulation of the nerve bundles around the hepatic artery and the portal vein resulted in an increase of glucose and lactate output, an enhancement of phosphorylase a activity and a decrease of portal flow. 2. Sodium nitroprusside prevented the hemodynamic changes after nerve stimulation without affecting the metabolic alterations. 3. Phentolamine or an extracellular calcium level below 300 mumol x 1(-1) abolished both hemodynamic and metabolic changes after nerve stimulation, while propranolol or atropine were without effect. 4. Norepinephrine infusion mimicked nerve stimulation only at the highly unphysiological concentration of 0.1 microM; it was not effective at a concentration of 0.01 microM, which might be reached in the sinusoidal blood due to an overflow from intrahepatic synapses. The present results suggest that, in rat liver, glycogen breakdown is regulated by alpha-sympathetic nerves directly rather than indirectly via hemodynamic changes or via norepinephrine overflow.

Animals↗

[Further characterization of lipopolysaccharides from Pasteurella multocida].

The biological properties, sedimentation behaviour, and electron-optically visualised structures of lipopolysaccharides from Pasteurella multocida were found to be identical with lipopolysaccharides from Enterobacteriaceae. Hard evidence to the effect that lipopolysaccharides from Pasteurella multocida are R-lipopolysaccharides were produced by the composition of monosaccharides together with experiments on the basis of disc electrophoresis.

Animals↗

[Tricyclic antidepressants (TAD) as a cause of unexpected death (author's transl)].

This study points to the controversy over the anti-depressant efficacy of tricyclic antidepressant drugs (TAD) and emphasize their cardiotoxicity. The number of lethal poisoning cases--from the Swiss federal statistics on the cause of death--amounted to 54 for the period from 1967 to 1976. Ten of these 54 cases occurred in children who had ingested the drug accidentally; the remaining cases concerned adults who took an overdose of the drug intentionally. In addition, the authors reviewed the forensic medical examinations performed on 11 cases of unexpected death due to lethal poisoning with TAD. Our data indicated that fatality can follow drug intake quite rapidly. Autoptical and histological findings were not specific. To confirm a poisoning diagnosis, levels of TAD and their metabolites were therefore determined in nine cases in various organ tissues and body fluids. Poisoning was due to imipramine (3 cases), opipramol (2 cases), dibenzepine (3 cases), and amitriptyline (3 cases).

Accidents, Home↗

[Measuring procedure for the determination of the location, nature and size of metallic foreign objects in the eye by means of an electromagnetic sensor (author's transl)].

A new electromagnetic localization technique for determination of foreign bodies in the eye provides, according to initial experiments carried out under test conditions, both more exact localization than that possible with the usual techniques, and information regarding the magnetic properties and the size of the foreign body. In the following article, the basic principles of this new method are presented, together with the first experimental results obtained with the electromagnetic sensor.

Electromagnetic Phenomena↗

[Endocrine pancreas function in cattle. I. Age-dependent responses in cattle as well as correlations between the mother animal and the fetus or the newborn].

An account of relevant literature is followed by reference to studies undertaken into age dependence of insulin levels in the blood and into the function of the endocrine pancreas in the peripartum period. The mean plasma insulin concentrations recorded from 251 heads of cattle of different age groups varies between 0.90 ng/ml and 1.90 ng/ml, and they did not exhibit any age-dependent alteration. A positively significant correlation coefficient between insulin and glucose levels in the blood was calculated for calves, aged three days and more. No significant correlations were found to exist between those two parameters in younger animals and in adult cattle. Parturition proper was accompanied by rise in insulin in the blood of mother animals. No difference between blood insulin of mother animals and blood insulin of their own newborn calves was observed up to twelve hours from parturition. Diaplacental insulin passage was established for cattle.

Aging↗