The effects of progesterone on follicular growth in the rabbit ovary

Studies were undertaken to measure the growth of follicles in the rabbit ovary during periods of elevated blood levels of progesterone. The progestin was increased in the blood by pregnancy or by implantation of progesterone pellets, which raised blood progesterone to near the levels measured during pregnancy. After 1, 2, 3, or 4 weeks of pregnancy or progesterone-pellet treatment, follicles of 1.0 mm external diameter or greater were dissected out of the ovaries and their external diameters were measured; then, each follicle was extracted for measurement of estradiol content. Blood levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured in these animals as well. Follicles up to 2.5 mm in diameter were found in the ovaries of nonpregnant and untreated animals while 1.8 mm was the maximal size found during pregnancy or progesterone-pellet treatment. Furthermore, both in pregnant and in progesterone-treated rabbits, the follicular estradiol content and concentration were significantly suppressed compared to follicles from untreated rabbits. The progesterone pellets had no major effect on the levels of LH and FSH in the blood; the concentration of these gonadotropins in the progesterone-treated rabbits was virtually identical to levels previously measured in the blood of pregnant animals. The results of these studies indicate that progesterone exerts an inhibitory action on follicular development and steroidogenic function in the rabbit ovary. The progesterone action appears to be exerted directly on the ovary and is not indirect, by way of an inhibition of gonadotropin secretion.     

Direct measurement of the initial proton extrusion to oxygen uptake ratio accompanying succinate oxidation by rat liver mitochondria.

The problem of obtaining very early ratios for the H+/O stoichiometry accompanying succinate oxidation by rat liver mitochondria was attacked using new techniques for direct measurement rather than extrapolations based on data obtained after mixing and the recovery of the electrode from initial injection of O2. Respiration was quickly initiated in a thoroughly mixed O2-containing suspension of mitochondria under a CO atmosphere by photolysis of the CO-cytochrome c oxidase complex-. Fast responding O2 and pH electrodes were used to collect data every 10 ms. The response time for each electrode was experimentally measured in each experiment and suitable corrections for electrode relaxations were made. With uncorrected data obtained after 0.8 s, the extrapolation back to zero time on the basis of single-exponential curve fitting confirmed values close to 8.0 as previously reported (Costa et al., 1984). The data directly obtained, however, indicate an initial burst in H+/O ratio that peaked to values of approximately 20 to 30 prior to 50 ms and which was no longer evident after 0.3 s. Newer information and considerations that place all extrapolation methods in question are discussed.     

The distribution of hair of the lower limb in white and Negro males

Four types of distribution of terminal hair of the lower limb are recognized. These types are pedo-cruro-femoral, cruro-femoral, pedo-femoral and femoral. These are correlated with the types of distribution of terminal hair of the upper limb, and their incidence is reported. In addition, three hair patterns of the leg are named and described.     

The distribution of anterior cervical hair in white and Negro males

Patterns of hair distribution of the front of the human neck are recognized. The basic patterns are supraclavicular, suprasternal and supraclaviculosuprasternal. They are correlated with the types of chest hair distribution.     

Hypotension caused by intravenous infusion of rifampicin and its relation to the administration schedule

It was shown in studies on animals that bolus administration of rifampicin induced hypotension whose severity depended on the rate of the antibiotic administration. When the antibiotic was administered in the 5-, 10- or 15-minute regimen in a dose of 10 mg/kg the maximum decrease in blood pressure was 44, 34 or 21% of the initial level and the maximum antibiotic concentration attained in the blood was 34.4, 27.2 or 22.6 micrograms/ml, respectively. With the infusion for 30 minutes, the maximum antibiotic concentration in the blood was 17.6 micrograms/ml and the blood pressure did not undergo any significant changes. When the rate of the antibiotic infusion was high there was pharmacokinetic heterogeneity of the blood serum and biophase which could lead to unpredictable results. After repeated administrations of rifampicin to the same animals pronounced tachyphylaxis to the antibiotic was noted, which manifested itself in decreasing of hypotension, though the serum antibiotic level was 1.5 to 2 times higher that the initial one. It was concluded that administration of rifampicin in the therapeutic dose equal to 10 mg/kg for 30 minutes was the most sparing regimen for the antibiotic bolus intravenous infusion. Gradual increase in the antibiotic dose and administration rate in patients is possible under careful control of blood pressure and pharmacokinetic studies.     

15-hydroxyeicosatetraenoic acid stimulates migration of human retinal microvessel endothelium in vitro and neovascularization in vivo

We evaluated 15-hydroxyeicosatetraenoic acid (15-HETE), a major arachidonic acid product of vascular endothelium and leukocytes, for its effect on neovascularization. In a modified Boyden chamber assay, 15-HETE (10⁻⁷ M) sitmulated human retinal microvessel endothelial cell migration by 42 ± 10% (mean ± S.E.M., p<0.01). 12-HETE, a major arachidonic acid metabolite of platelets, had no such effect. Further studies in the rabbit corneal pocket assay revealed that 15-HETE stimulated neovascularization . Concentrations at which the effects were observed are within the range generated by several cell types and are achievable in human serum. 15-HETE stimulation of human endothelial cell migration and neovascularization suggests that it may play a role in vasoproliferative disorders.     

AtHsp101 research sets course of action for the genetic improvement of crops against heat stress

Journal of Plant Biochemistry and Biotechnology - Caseinolytic protease (Clp)/Hsp100 proteins are members of the AAA+ (ATPase associated with a variety of cellular activities) family of proteins...