On the validity of free hormone measurements

The influence of equilibrium perturbation on the measurement of free or non-protein-bound hormones in serum or plasma is described. The free analyte concentration in the sample will alter after dilution or addition of binding reagents. The extent of this perturbation is not constant. It depends on the binding properties of the endogenous carrier proteins which vary from sample to sample and from sample to reference standard. As examples, the different changes of the free thyroxine and free cortisol concentrations after dilution are demonstrated both experimentally and by theoretical modeling of the hormone-protein distribution. It is shown how this systematical error can be minimized in the design of free hormone assays.

46,XX/46,XY chimerism in a phenotypically normal man

Some twenty cases of dispermic chimeras with the karyotype 46,XX/46,XY, discovered because of gonadal dysplasias or a true hermaphroditism, have been reported. This is a report of a phenotypically normal man with 46,XX/46,XY chimerism in whom a prepubertal finding of positive X-chromatin was interpreted as Klinefelter syndrome. The diagnosis was revised 11 years later when the family doctor, who doubted the earlier diagnosis because of the patient's normal-sized testes, sent him to an outpatient clinic. The young man was 23 years old, athletic (74kg, 180cm), with normal body proportions, normal sexual hair distribution, normal libido and potency, normal endocrine parameters, and a normal spermiogram. The karyotype revealed an XX/XY mosaic in a proportion of 1:2. An identical set of maternal markers (Q- and C-banding) was present in male and female cells. Differences were found with respect to two paternal markers. Furthermore, blood, serum, and red cell enzyme groups in five systems showed two phenotypes, again with duality of paternal origin. It is concluded that a positive X-chromatin in prepuperty, especially in the absence of supporting clinical features, must be followed by a karyotype study.

Nickel requirement of Acetobacterium woodii

Growth of Acetobacterium woodii on H2 and CO2 rather than on fructose was dependent on nickel. Nickel-deprived cultures growing on fructose did not synthesize acetate from CO2; under these conditions hydrogen formation was used as the electron sink. The data indicate that nickel is involved in CO2 reduction to acetate in A. woodii.

Circumvention of the tumor membrane barrier to WR-2721 absorption by reduction of drug hydrophilicity

In attempting to account for the ability of most solid tumors to restrict the absorption of WR-2721, aminopropyl-aminoethylphosphorothioate, we examined a number of drug characteristics which might allow for this restriction, and observed that drug hydrophilicity was a major contributing factor. When the highly hydrophilic WR-2721 was dephosphorylated, the drug became less hydrophilic and could readily cross tumor cell membranes. In addition, conventional radioprotectants, such as cysteine and mercaptoethylamine, were shown to be less hydrophilic than WR-2721 and also to cross tumor membranes readily. Therefore, drug hydrophilicity would appear to be the factor underlying the ability of WR-2721 to selectively protect normal tissues while most other protectors alter the radiation resistance of normal and tumor tissue alike. A red blood cell model for studying this problem in greater detail is described.

Functional and dysfunctional uterine bleeding

The patient who comes to the physician with abnormal bleeding represents an enormous responsibility. The various causative factors represent defects in numerous physiologic systems. The diagnosis of DUB still requires further investigation of the hormonal imbalance. Only when specific causes are known can the treatment be tailored to the particular patient. Recent scientific advances regarding possible cellular mechanisms for DUB make it mandatory that the primary physician be aware of available tests that may indicate the relative appropriateness of and prognosis for a particular therapy. The treatment is substitutional. If progesterone is missing, therefore,the treatment should replace it. Progesterone may be obtained endogenously by ovulation induction or exogenously by oral or parenteral progestogens.

On the kinetics of consecutive, bimolecular reactions

It is shown that the differential equations governing the kinetics of consecutive, bimolecular reactions can be reduced to an Abel equation.

Mathematical analysis of energy regulatory pattens of normal and diabetic rats

Analysis of feeding patterns indicated that diabetic (alloxan) hyperphagia is characterized by doubling of meal sizes with no change in feeding frequency. Correlation of meal sizes and intermeal intervals did not provide any systematic relationships for either normal or diabetic rats. When equations of the general form Y = A + Bcos (X) were fit to successive satiety ratios (postmeal interval/meal size), the diabetic rats showed significantly lower A coefficients, reflecting a lower average level of satiety, as well as significantly lower B coefficients, reflecting less systematic variability in the satiating value of food around the average level. It is concluded that the major regulatory deficit in diabetic animals is a chronic reduction in the long-term signal of body nutrient repletion.