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Biomedical subjects

M Lehmann

Publications and source records attributed to M Lehmann.

At least 361 records · Page 20Linked to original sources
PubMed1977

New prospects for a prolonged functional life-span of artificial hip joints by using the material combination polyethylene/aluminium oxide ceramin/metal.

Investigations over the years have shown that the mirror-finished Al2O3 ceramic is a much more suitable frictional counterpart to ultrahigh molecular weight (UHMW) polyethylene than metal. Despite the extremely gread hardness difference between polyethylene and Al2O3 ceramic, a considerable lower wear rate is obtained for the polyethylene socked with this new low-friction material combination. The unexpectedly favorable tribological behavior of this ceramic material in contact with polyethylene may be attributed to the following factors: better values for corrosion resistance characteristics, wettability with liquids, surfact gloss, hardness, and scratch resistance of the ceramic material in comparison with those of the hitherto used metallic implant materials (AISI-316L steel or cast Co-Cr-Mo alloy). It appears that, by using this new combination of materials for the socket and the ball, it will be possible to prolong the service life of artificial hip joints considerably without having effecy any fundamental changes in the present design and implantation principle retaining the hitherto used anchorage shaft made of wrought Co-Ni-Cr-Mo-Ti alloy Protasul-10 of extremely high corrosion fatigue strength.

Alloys↗
PubMed1976

Accumulation, mobilization and turn-over of glycogen in the blue-green bacterium Anacystis nidulans.

1. Accumulation of glycogen up to a constant amount per cell was observed during the postexponential phase of growth, in the presence of an excess of a utilizable carbon source. Cell multiplication was reproducibly controlled by growth of the organism in a nitrogen-limiting medium under photoautotrophic conditions (presence of light, air plus CO2). 2. Temporary starvation, i.e. by removal of light or by the addition to an illuminated culture of DCMU, 3-(3',4'-dichlorophenyl)-1,1'-dimethylurea, a specific inhibitor of photosystem II, lead to a mobilization of glycogen in the cell. Furthermore, Anacystis nidulans, having accumulated glycogen by virtue of preculture under nitrogen-limiting conditions, will resume cell division when the culture medium is complemented with a nitrogen source. The ability of the organism to use glycogen as an endogenous carbon source for growth was observed by addition of a nitrogen source to nitrogen-starving cells and simultaneous removal of CO2. 3. During the period of constant amount of glycogen per cell the reserve polysaccharide was subject to turnover as demonstrated with a pulse chase-labelling technique. The demonstration of a turnover--for the first time with a bacterial species--indicated a strict balance in the relative rate of synthesis and degradation.

Cell Division↗
PubMedDate not supplied

Choice of therapy for imported cases of falciparum malaria in children: a retrospective study of 100 cases seen in Marseilles, France.

We have carried out a retrospective study on 100 children in hospital in Marseilles, France with a diagnosis of Plasmodium falciparum malaria. On admission, the main clinical features were anaemia (90 cases), fever (83 cases, > 40 degrees C in 22 cases), hepatomegaly (44 cases), vomiting (29 cases), neurological signs (22 cases), thrombocytopenia (13 cases), hyperparasitaemia (6 cases), jaundice (4 cases), shock (1 case) and hypoglycaemia (1 case). Severe malaria, as defined by the World Health Organization Malaria Action Programme, was rare in our study (only 2 cases) and the prognosis was good (no death, no sequela). The search for neurological signs such as impaired consciousness, prostration or convulsions is an effective and simple way to diagnose potentially severe cases. In the presence of these signs, intravenous quinine treatment resulted in a shortened duration of fever (30 h instead of 63 h) and thereby avoided patients becoming worse. In children without neurological signs or persistent vomiting, oral therapy may be used even if there is high fever or hyperparasitaemia, but close surveillance is required. Patients treated with halofantrine or mefloquine had a shorter stay in hospital than those treated with chloroquine (mean = 4 d instead of 5.7 d). The resistance of some strains to chloroquine may explain this difference.

Administration, Oral↗