Larry R. Laufer

Physical characteristics and sex hormone levels in patients with osteoporotic hip fractures or endometrial cancer.

Comparisons were made of the physical characteristics and the sex hormone levels of 50 postmenopausal women, half of whom had sustained an osteoporotic hip fracture while the remainder had developed endometrial carcinoma. None of the patients had received estrogen replacement therapy for longer than 3 months during their lifetime. At the time of injury hip fracture patients were found to be lighter (121 +/- 5 versus 167 +/- 9 pounds) and older (73.4 +/- 1.0 versus 62.6 +/- 1.7 years) than the cancer patients at the time of diagnosis. Estrone, estradiol, percentage of free estradiol, and free estradiol levels were significantly lower in the hip fracture patients than in subjects with endometrial cancer, while sex hormone-binding globulin levels were significantly higher in the former group. Androstenedione and testosterone levels were similar. Previous studies have shown that the incidence of both lesions is influenced by body size. These data suggest that body size may exert this influence through alteration of endogenous estrogen metabolism with hip fracture patients having lower concentrations and endometrial cancer patients having higher concentrations of endogenous estrogens.

Impermeability of the Rat Blood-Brain Barrier to Exogenously Administered Gonadotropin-Releasing Hormone

To assess the permeability of the blood-brain barrier (BBB) to exogenously administered gondatrophin-releasing hormone (GnRH), a study was performed in male-rats using the double isotope, intracarotid, single injection technique of Oldendorf. The mean (+/- SEM) brain uptake indices (BUI) of 3H-GnRH in comparison to a freely diffusible reference compound, 14C-butanol, were 1.1 +/- 0.2, 3.5 +/- 0.7 and 3.0 +/- 0.6 when the injection vehicles were Ringers lactate, rat serum and human serum, respectively. The BUI of 3H-GnRH was similar to that of 3H-inulin, a nondiffusible compound. With different concentrations, the BUI of 3H-GnRH did not change significantly. These data indicate that the BBB of the male rat is impermeable to exogenously administered GnRH.