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Electron spin resonance measurements have been made on the copper(II) chelates of o-methylmercaptobenzoic acid, S-carboxydiethyldithiocarbamic acid, thiazolidine-4-carboxylic acid, 5-hydroxy-1,3-benzoxathiol-2-one and diacetyl bisthiosemicarbazone. The e.s.r. spectra of dimethylformamide solutions of the chelates have been interpreted in terms of dimeric species which are believed to exist at room temperature, as well as in frozen solutions in the case of o-methyl-mercaptobenzoic acid, S-carboxydiethyldithiocarbamic acid, and 5-hydroxy-1,3-benzoxathiol-2-one, whereas the dimeric forms of the remaining chelates are formed solely in frozen solution. The results have been interpreted as arising from dipole-dipole coupling between the copper(II) ions in their dimeric forms, and a line simulation procedure employed to extract the distance between the copper(II) dipoles. This information has been used to suggest the possible structures of the dimeric species. The effect of the introduction of zinc(II) ions during the formation of the copper(II) chelates has been assessed in each case.

A double isotope derivative method for the estimation of progesterone in 10 ml peripheral plasma, using 35S-thiosemicarbazide (100 mc/mM) as reagent and 1,2-3H-progesterone (0.8 mμg, 87 μc/μg) a s indicator, is described. Purification is achieved by chromatography of the first derivative formed, progesterone bisthiosemicarbazone, by a silica gel thin layer and a paper system, hydrolysis to progesterone 3-thiosemicarbazone and chromatography of this derivative by a thin layer system, and finally acetylation to the 3-thiosemicarbazone 2′,4′-diacetate, and subsequent chromatography of this derivative on one thin layer and one paper system. The values given by 10 ml water samples and the same volume of plasma from ovariectomized, adrenalectomized subjects were 0.0020 ±0.0009 (sd) ±0.0002 (se) μg (23 samples) and 0.0029 ±0.0013 (sd) ±0.006 (se) μg (5 samples), respectively. These mean values were therefore the nonspecific blank of the method. No known naturally occurring steroids were found to interfere with the estimations. The precision and accuracy of the analysis of quantities of progesterone present in the plasma of normal women was found to be 7.5%. The standard error of the estimate was 0.0009 μg/10 ml in the lower range of values without subtraction of the nonspecific blank, which also had a standard deviation of 0.0009 μg/10 ml. Values (corrected for the appropriate water blank) for plasma taken from normal young women in the luteal and follicular phase of the cycle were 1.04 ±0.32 (sd) ±0.13 (se) (7 samples) and 0.113 ±0.049 (sd) 0.021 (se) ±/100 ml (5 samples). Plasma from ovariectomized females gave 0.039 ±0.010 (sd) ±0.004 (se) μg/100 ml (6 samples) (corrected for blank), indicating that the ovaries of normal women secrete progesterone or a precursor throughout the cycle. Plasma from males gave 0.028 ±0.013 (sd) ±0.004 (se) μg/100 ml (13 samples) (corrected for blank), which is similar to the values for ovariectomized females, although the excretion of urinary pregnanediol is much higher in males than in ovariectomized females. This indicates that urinary pregnanediol is not a unique metabolite of plasma progesterone in young males.