Plasma concentrations of luteinizing hormone and progesterone during superovulation of dairy cows using follicle stimulating hormone or pregnant mare serum gonadotrophin

Eighteen lactating Holstein cows were randomly divided into three groups of equal size. Six cows were not superovulated; the remaining cows were superovulated using either FSH-P or PMSG beginning on Day 12 of the estrous cycle (day of ovulation = Day 0). Animals treated with FSH-P were injected intramuscularly (i.m.) with 4 mg FSH-P every 12 h for 5 d. PMSG was administered i.m. as a single injection of 2350 IU. Cloprostenol (PG, 500 ug) was injected i.m. 56 and 72 h after commencement of treatment and at the same time in the cycle of controls. All cows were inseminated 56, 68 and 80 h after the first PG injection. Blood samples (5 ml) were collected daily and every 15 min for a period of 9 h on Days -1, 0, 2, 8 and 10, with continuous blood sampling at 15-min intervals during Days 3 to 6. Ovulation rate was 27.7 +/- 8.22 in animals treated with PMSG, and 8.0 +/- 3.2 embryos per donor were recovered. In the FSH group, ovulation rate was 8.3 +/- 1.48 and 3.0 +/- 1.1 embryos per donor were recovered. Progesterone concentrations were similar in all three groups until the onset of the LH surge, when progesterone concentrations were greater (P<0.05) in animals of the PMSG group. After the preovulatory LH surge, concentrations of progesterone started increasing earlier (44 h) in cows treated with PMSG, followed by FSH-treated cows (76 h) and controls (99 h). The LH surge occurred earlier (P<0.05) in PMSG-treated cows (37 h after first PG treatment), than in animals treated with FSH-P (52 h) or controls (82 h). In animals treated with FSH-P, the magnitude of the preovulatory LH surge (24.2 +/- 1.02 ng/ml) was higher (P<0.05) than in the other two groups (PMSG = 17.1 +/- 2.04 ng/ml; control, 16.7 +/- 1.24 ng/ml). Superovulation with FSH-P or PMSG did not affect either mean basal LH concentration, frequency or amplitude of LH pulses during Days -1, 0, 2, 3, presurge periods, or Days 8 and 10 post-treatment. At ovariectomy, 8 d post-estrus, more follicles > 10 mm diam. were observed in the ovaries after treatment with PMSG (8.5 +/- 5.66) than after treatment with FSH-P (0.7 +/- 0.42) (P<0.05). Maximum concentrations of PMSG were measured 24 h after administration. Following this peak, PMSG levels declined with two slopes, with half-lives of 36 h and 370 h.     

Comparative aspects of the area postrema: fine-structural considerations help to determine its function

The area postrema is a circumventricular organ of the fourth ventricle of the mammalian brain. Although there are distinct gross anatomical differences in the appearance of this organ between "lower" mammals such as rodents and lagomorphs and "higher" mammals such as carnivores and primates, its fine structure is remarkably similar in all species studied. There are many suggestions in the literature for a specific function for this area of the brain, ranging from its being a chemoreceptive trigger zone for the emetic response to its being a regulatory nucleus for the sleep cycle. The present report describes some comparative studies on the ultrastructure of this organ. This information is discussed in relation to what is known about the neurochemistry of the area postrema and its connections with other brain regions and visceral structures. A suggestion is offered that our current knowledge of the area postrema is consistent with its performing many of its proposed functions in the context of a regulatory ("fine-tuning") center for many autonomic functions.     

The influence of androgen administration on the structure and function of the brain-pituitary-gonad axis of sexually immature platyfish,Xiphophorus maculatus

Summary This report demonstrates that the administration of testosterone (T) or 11-ketotestosterone (11-KT) to sexually immature (8 wks old) male platyfish (Xiphophorus maculatus) of early-and late-maturing genotypes affects the synthesis and/or release of luteinizing hormone-releasing hormone (LHRH), as assessed by immunocytochemical evaluation, increases the number and activity of pituitary gonadotropes, stimulates the production of sperm and, thus, advances the age of sexual maturation over that dictated by the genome. We also show that 11-KT and T affect different LHRH-containing centers in the brain and have differential effects on rate and degree of sexual maturation, regardless of whether the hormones are administered to early or late-maturing genotypes.     

Metabolic abnormalities in children of non-insulin dependent diabetics.

Non-insulin dependent diabetes appears to be an inherited condition. A study of young offspring of non-insulin dependent diabetics was conducted to determine whether metabolic abnormalities could be found at a young age before clinical diabetes developed. Thirteen patients with non-insulin dependent diabetes were selected who fulfilled the following criteria: they had a sibling who also had non-insulin dependent diabetes, their spouse was non-diabetic, and the offspring were aged between 12 and 45 years, not diabetic, and available for study. All 32 offspring had a 75 g oral glucose tolerance test, and results in 13 of them, one randomly selected from each family, were compared with 13 controls of similar age, sex, and weight. The offspring had significantly higher fasting concentrations of glucose, higher proportions of haemoglobin A1, and higher concentrations of insulin, C peptide, and glucagon. After glucose challenge the increases in both glucose and C peptide concentrations were significantly greater in the offspring. These differences were maintained in all 32 offspring when compared with 18 controls of similar age, sex, and weight; seven of the 32 offspring had impaired glucose tolerance. These results indicate that young offspring of selected non-insulin dependent diabetics can show extensive metabolic changes including impaired glucose tolerance. These changes are associated with hyperinsulinaemia and hyperglucagonaemia.     

Absence of Significant Light-Induced Changes in cAMP Levels in Sporangiophores of Phycomyces blakesleeanus

We were unable to find transient changes in the amount of cAMP or cGMP that had been proposed to mediate the light-growth response in sporangiophores of Phycomyces blakesleeanus.     

Ionic mechanisms in secretagogue-induced morphological changes in rat parotid gland

When 10(-5) M carbachol was added to parotid tissue slices incubated in buffer containing Ca++, watery vacuoles were formed in the cells. The percent volume density of vacuoles, as measured from 0.5-micron sections, increased from 0.64 +/- 0.15 SE (n = 7) to 3.09 +/- 0.99 (n = 5) in 10 min and, finally, to 7.27 +/- 1.88 (n = 4) in 30 min. In electron micrographs, most of the vacuoles appeared to arise from a location near the Golgi apparatus. Condensation of nuclear chromatin and a conformational change in mitochondria were also noted immediately after stimulation. The percent volume density values returned to basal levels with the addition of either 5 mM EGTA or 10(-6) M atropine after the addition of carbachol. Nuclei and mitochondria returned to normal configurations. In the presence of either 1 mM ouabain or high K+, or in the absence of added Ca++, carbachol failed to induce vacuole formation. However, low Na+ medium did not prevent the formation of vacuoles due to carbachol. Ultrastructural changes in nuclei and mitochondria were consistently associated with the appearance of vacuoles. Since both high K+ and ouabain blocked vacuole formation, it is unlikely that Na+ or K+ movements were important for the response. Rather, receptor-activated Ca++ influx, which is likely to be inhibited by depolarizing agents (such as high K+ or ouabain), is probably the more important factor in vacuole formation and other concomitant ultrastructural changes.     

Mechanism of catalase induction in Rhodopseudomonas spheroides: Role of porphyrin excretion

Summary Catalase induction in Rhodopseudomonas spheroides and three locally isolated strains of Rhodopseudomonas (TL-1, TL-4 and Rps. D) was studied. A correlation between the rate of excretion of porphyrin and the inducibility of the culture was observed. 8-hydroxyquinoline at 4x10^-5 M had no effect on Bchl synthesis but it inhibited porphyrin excretion and catalase induction in Rhodopseudomonas spheroides. 8-OH Q at this concentration partially inhibited Bchl synthesis and catalase induction in strain TL-1. The data indicate that the amount of catalase produced is dependent on the pool size of porphyrins.Abbreviations used ALA -amino laevulinic acid - Bchl Bacteriochlorophyll - EDTA Ethylene diamine tetra acetate - DMSO Dimethyl sulfoxide - 8-OH Q 8-hydroxyquinoline - nm nanometer - Rh. Rhodopseudomonas This work is part of a thesis submitted by K. T. Shanmugam in partial fulfillment of the requirements for the Ph. D. degree.