Ueber Mischgeschwülste des Hodens

Ohne Zusammenfassung (Mit 9 Abbildungen im Text und Tafel II.)     

Oscillating platelet counts in healthy individuals: experimental investigation and quantitative evaluation of thrombocytopoietic feedback control

Peripheral platelet counts of 5 healthy women and 5 healthy men were studied over 54 to 100 d to assess whether statistically significant fluctuations could be detected. Low amplitude fluctuations were found in 7 of the 10 individuals with mean periods of 28.3 +/- 3.4 d, using autocorrelation analysis. To understand the origin of such fluctuations, a simple linear feedback model of thrombocytopoiesis was formulated and quantitatively analyzed. This model, together with literature data on platelet-turnover in healthy individuals and patients with idiopathic thrombocytopenic purpura (ITP), predicts states in which oscillations are likely to occur and explains these as a result of optimum tuning of the feedback system to respond quickly to disturbances in the platelet pool. Both in healthy individuals and patients with cyclic thrombocytopenia, the typical periods of the fluctuations predicted by the model of about 25 d are in good agreement with the data.     

Dextrose and vigilance: the effect of dextrose on the spectro-analytic parameters of pharmaco-EEG]

In a randomized single-blind cross-over-design the effect of 15 g dextrose was investigated against placebo with 48 healthy subjects at two different days each. The quantitative pharmaco-EEG was recorded occipitocentral at the left side (O1-Cz) under vigilance controlled conditions and then under resting conditions (three minutes each). Having measured its baseline it was repeated six times every 20 minutes starting 10 minutes after the application of the substance. After the administration of dextrose a stabilization of vigilance could be seen in the EEG by the following differences of statistical significance (p < = 0.05) between dextrose and placebo under resting recording conditions: In the first control (14.-16. minute post) there was a significant decrease of the relative power in the delta and in the theta range combined with an increase of alpha 2. In the second control (34.-36. minute post) there was a significant decrease of relative power in the theta range and significant increase in the alpha 1 range. In the third control (54.-56. minute post) and later on no effects of dextrose were left in the pharmaco-EEG. The significant differences in the first and second control have to be interpreted as follows: After the administration of dextrose the level of vigilance was increased compared to the placebo group.     

Crystal structure of Z-DNA without an alternating purine-pyrimidine sequence.

In left-handed Z-DNA, consecutive nucleotides along the chain alternate in the syn and anti conformations. Purine residues form the syn conformation readily and up to now all Z-DNA crystal structures have sequences of alternating purines and pyrimidines. However, we find that d(C-G-A-T-C-G) with the cytosines brominated or methylated on C-5 crystallizes as Z-DNA. The structure reveals thymines in syn and adenines in anti conformations. This suggests that Z-DNA may occur in sequences other than those with alternating purine-pyrimidine sequence.     

Inhibition of monoamine oxidases A and B by simple isoquinoline alkaloids: racemic and optically active 1,2,3,4-tetrahydro-, 3,4-dihydro-, and fully aromatic isoquinolines

A series of 1,2,3,4-tetrahydro-, 3,4-dihydro-, and fully aromatic isoquinolines were tested as substrates and/or inactivators of highly purified human monoamine oxidase A and B (MAO A and B). None were found to be a substrate for either enzyme, but many of these isoquinolines could selectively inhibit either MAO A or B. Stereoselective competitive inhibition of MAO A was found with the R enantiomer of all the stereoisomers tested, including salsolinol (Ki = 31 microM), salsoline (Ki = 77 microM), salsolidine (Ki = 6 microM), and carnegine (Ki = 2 microM). As a class, the 3,4-dihydro-isoquinolines were the most potent inhibitors tested (Ki = 2-130 microM), and the fully aromatic isoquinolines had intermediate activity (Ki = 17-130 microM) against MAO A. In contrast, only a few of these compounds markedly inhibited MAO B. 1,2,3,4-Tetrahydroisoquinoline, its 2-methyl derivative, and o-methylcorypalline gave apparent Ki values of 15, 1, and 29 microM, respectively, and two 3,4-dihydroisoquinolines (compounds 22 and 25) showed substantial inhibition of MAO B (Ki = 76 and 15 microM, respectively). These results support the concept that the topography of the inhibitor binding site differs in MAO A and B.