A seminiferous tubular factor is not obligatory for regulation of plasma follicle-stimulating hormone in the rat.

Plasma testosterone, FSH, and LH levels were measured by RIA in sham-castrate control rats and in castrate male rats with testosterone-containing Silastic capsule implants to evaluate the relative contribution of testosterone and inhibin in maintaining normal FSH secretion in vivo. Silastic capsules maintaining normal testosterone levels maintained normal levels of both FSH and LH over the 5-day course of these studies. The data suggest that testosterone or its metabolites can account for at least 78%, and possibly all, of the FSH-suppressing activity of the testis. The data do not support an obligatory role for other testicular factors, such as inhibin, in the regulation of plasma FSH when normal testosterone levels are maintained.

Value of right-sided cardiac catheterization in patients undergoing left-sided cardiac catheterization for evaluation of coronary artery disease.

The value of right-sided cardiac catheterization was assessed prospectively in 200 patients undergoing left-sided catheterization for evaluation of known or suspected coronary artery disease. Before catheterization, data from right-sided catheterization was not felt to be necessary for clinical management. There were 6 +/- 2 extra minutes of procedure time and 86 +/- 63 extra seconds of fluoroscopy time used. Abnormalities were detected in 69 (35%) patients. These findings were unexpected in 37 of these patients and in 3 patients, further evaluation was prompted. However, management was altered in only 3 (1.5%) patients as a result of data obtained by right-sided catheterization. In conclusion this additional procedure rarely adds clinically useful information about patients undergoing left-sided catheterization and angiography for coronary artery disease without a clinical indication for right-sided catheterization.

Thermal stability of a long-acting analogue of luteinizing hormone releasing hormone (D-trp6-pro9-NEt-LHRH).

The stability of solutions of a long-acting analogue of luteinizing hormone releasing hormone (D-trp6-pro9-NEt-LHRH [LHRHa] after heating to 60C for 5 days, after repeated freezing and thawing, and after refrigeration at 4C for 8 days has been examined. None of the treatments caused a detectable alteration in the HPLC profile, and none caused a significant change in biological activity in vivo. It is concluded that D-trp6-pro9-NEt-LHRH can withstand mild heating, repeated freezing and thawing, and short-term refrigeration without apparent change in HPLC profile or biological activity. It is also concluded that the results obtained with the HPLC method correlate well with the results from the in vivo bioassay.

PIP: The stability of solutions of a long acting analogue of luteinizing hormone releasing hormone (D-trp6-pro9-NEt-LHRH [LHRHa]) after heating to 60 degrees Centigrade for 5 days, after repeated freezing and thawing, and after refrigeration at 4 degrees Centrigrade for 8 days was examined. The treatments administered to solutions 2 (60 degrees Centigrade x 5 days), 4 (7 freeze thaw cycles), and 5 (4 degrees Centigrade x 8 days) did not cause any change in the retention time or absorbance (at 210, 230, and 271 nm) of their HPLC profiles when compared to the control solutions 1 and 3. Control solutions degraded with sodium hydroxide (6) showed no LHRHa peak. A 1:1 mixture of the degraded and control solutions (7) gave a peak height of LHRHa that was 51.2% of control. Each of the 5 solutions showed similar biological activity. No effect was seen at a dose of 8 ng, whereas 24 ng caused a significant LH rise (218-277% of the basal level) for each solution. The parallel line potency estimate for solution 2 (60 degrees Centigrade x 5 days) relative to solution 1 was 0.77 (95% confidence limits, 0.32-1.48). The potency ratio for solution 4 (7 freeze thaw cycles) relative to solution 3 was 0.85 (95% confidence limits, 0.23-2.26). In sum, the D-trp6-pro9-NEt-LHRH can withstand mild heating, repeated freezing and thawing, and short term refrigeration without apparent change in HPLC profile or biological activity. The results obtained with the HPLC method correlate will with the results from the "in vivo" bioassay.