Biomedical subjects
K H Roth
Publications and source records attributed to K H Roth.
[From eugenics to reproduction medicine].
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The legalization of mercy killings in medical and nursing institutions in Nazi Germany from 1938 until 1941. A commented documentation.
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Repeated exposition to subinhibitory concentrations of antibiotic in vitro readily decreases susceptibility of Neisseria gonorrhoeae to rifampicin, but not to new cephalosporins and penicillin G.
Repeated subcultivation of Neisseria gonorrhoeae in the presence of subinhibitory concentrations of antibiotic has turned out as a reliable model to predict the low potential for development of resistance with respect to the beta-lactam antibiotic penicillin. Before large-scale introduction of the new cephalosporins we exposed 5 N. gonorrhoeae strains of different susceptibility to penicillin repeatedly to subinhibitory concentrations of cefotiam, ceftizoxime, rifampicin and penicillin G incorporated into chocolate agar. each time the most resistant representatives of a strain were propagated, on the whole 25 times. While resistance to rifampicin increased readily (all strains became relatively resistant, MIC = 4 micrograms/ml), the same was not true of the cephalosporins. Although their susceptibility decreased, too, no strain acquired partial or even total resistance (final MIC less than or equal to 0.128 with cefotiam and ceftizoxime). The cephalosporins thus rather parallelled penicillin G which hardly induced any increase of resistance. Thus, a quick loss of clinical efficacy need not be feared after large-scale introduction of the new cephalosporins into the therapy of gonorrhea.
Formation and in-vivo-distribution of different 99mTc-Sn-pyrophosphate complexes.
The formation of two different 99mTc-Sn-pyrophosphate complexes was determined by evaluation of their in vivo distribution in rats. It was found that formation of a 2 : 2 Sn : PyP complex, which is bone seeking, is depending as well on the pyrophosphate as on the hydrogen ion concentration in the equilibrium. On the contrary, formation of a 2 : 1 Sn : PyP complex, which shows no bone affinity but concentrate in the kidneys, is hydrogen ion independent and occurs even at very low pyrophosphate concentrations. The probable structure of these complexes is discussed.