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Biomedical subjects

M Haun

Publications and source records attributed to M Haun.

49 records · Page 3Linked to original sources
PubMed1989

Effect of growth conditions on production of violacein by Chromobacterium violaceum (BB-78 strain).

1. Chromobacterium violaceum (strain BB-78 isolated in Brazil) produces violacein, a substance potentially useful in phototherapy and with antibiotic and trypanocide activity. Culture conditions were optimized for the production of violacein and changes in nutrients, temperature and pH were correlated to cellular growth. 2. Methionine was the only absolute requirement for growth. Alanine, arginine, tryptophan and vitamin B12 stimulated growth and the microorganism utilized both the D and L forms of methionine. L-Tryptophan and its metabolites were important as a carbon source for violacein production and bacterial growth. 3. The highest yields of violacein were obtained by incubation in liquid medium and in the absence of light at pH 7.0 and 28 degrees C for 24 h.

Chromobacterium↗
PubMed1986

Influence of varying afterload upon left ventricular contractility.

In open-chest rabbits under pentobarbitone anaesthesia the left ventricular afterload was varied by occlusion of the carotid arteries, descending aorta and both of them together in alternating sequence when the aortic nerves and cardiac vagal nerves were cut. Ascending aortic flow AF was recorded by means of a flow probe around the aortic root, the left ventricular pressure LVP by direct canulating of the heart and the aortic blood pressure AP via catheter through the left subclavian artery. From the LVP the systolic and diastolic values LVSP and LVEDP, the contractility index CI = (dp/dt/p)max and from the AF the stroke volume SV and strokework W were evaluated. At mild afterload elevation (carotid or aortic occlusion alone) the CI appears to be enhanced, SV diminished, LVEDP only little raised, and W improved. At combined occlusions a drastical rise of LVEDP, decrease of SV and impairment of W is observed whereas the CI remains elevated and the LVSP increases with AP. From the pump function diagram ensues that at mild afterload increase the operational point is shifted towards the strokework optimum whereas at high afterload it is far away. After discharge of the ventricle all alterations are rapidly and completely restituted.

Animals↗
PubMed1986

Comparative investigations of right and left ventricular contractility in the rabbit.

In pentobarbitone-anaesthetized open-chest rabbits the left and right ventricular pressures were measured. The contractilities of the left and right ventricle were expressed by the contractility index CI = (dp/dt/p)max. Evaluation of left and right ventricular systolic pressure and CIs was done before and at aortic nerve stimulation as well as with pacing and without pacing of the heart. Pressures and CIs appear to be four times greater in the left ventricle than in the right one. The values of the pressure ratio LVSP/RVSP resp. CI ratio CILV/CIRV are adequate before and after aortic nerve stimulation. Any effect difference between the left and the right aortic nerve stimulation does not exist. In the paced heart the left and right ventricular pressure and the left ventricular CI are lower than without pacing. The effect time courses of the left and right ventricle appear to be adequate. Hence is follows that the left rabbit ventricle predominates in contraction development.

Animals↗
PubMed1981

Synergistic effect of chlorpromazine and alkanals on the human red blood cells.

The hemolysis of human red cells in the presence of chlorpromazine and 2-methylpropanal, or propanal, has been studied by a spectrophotometric method. A strong synergistic effect was observed concomitant to the quenching of photon emission. The synergistic effect is consistent with the view that triplet excited species generated from a hemoprotein-catalyzed aerobic oxidation of aldehydes promotes "in situ" the photooxidation of chlorpromazine leading to products which have shown hemolytic effects. This view is supported by protection, albeit weak, offered by energy acceptors such as eosin and the 9,10-dibromoanthracene-2-sulfonate ion.

Acetaldehyde↗
PubMed1980

Excited indole-3-aldehyde from the peroxidase-catalyzed aerobic oxidation of indole-3-acetic acid. Reaction with and energy transfer to transfer ribonucleic acid.

The horseradish peroxidase catalyzed aerobic oxidation of the auxin indole-3-acetic acid generates triplet indole-3-aldehyde in high yield. The excited species is quenched by oxygen with formation of singlet oxygen, which is responsible for the observed photon emission and can be trapped by suitable agents. tRNA dramatically enhances the emission as a result of energy transfer from triplet indole-3-aldehyde to a 4-thiouridine group in tRNA. Triplet indole-3-aldehyde also adds covalently to tRNA. The results provide a possible mechanism for the auxin-tRNA interaction in vivo.

Aldehydes↗