Is there a role for contraceptive vaccines in fertility control?

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Gonadotropin releasing hormone in first trimester human placenta: isolation, partial characterisation and in vitro biosynthesis

Using a specific radioimmunoassay for gonadotropin releasing hormone, the presence of gonadotropin releasing hormone like material in the first trimester human placenta has been demonstrated. The material has been partially characterized using carboxy methyl cellulose chromatography, high pressure gel permeation chromatography and reverse phase C18 high pressure liquid chromatographic analysis. Analysis for bioactivity revealed that placental gonadotropin releasing hormone is much more active than synthetic gonadotropin releasing hormone in in vitro rat pituitary lutinising hormone release assay. In vitro biosynthetic studies using labelled precursors and immunoaffinity chromatography indicated that first trimester human placenta synthesizes gonadotropin releasing hormone like material

Trophoblast 'pseudo-tumorigenesis': Significance and contributory factors

Trophoblast cells of the human placenta proliferate, migrate, and invade the pregnant uterus and its vasculature in order to nourish the developing fetus, in a way that is imitated by malignant tumors. Many similarities exist between embryo implantation and the growth of cancer cells. We begin this article by reviewing decades of studies that have helped unearth the mechanisms that contribute to the tumor-like phenotype of human trophoblast cells. Interestingly, these attributes are only transient in nature, with stringent spatial and temporal confines. The importance of intrinsic molecular controls that effectively circumscribe the extent and duration of trophoblast incursion, becomes increasingly evident in abnormal pregnancies that are characterized by aberrant trophoblast proliferation/invasion. We summarize and discuss the significance of abnormalities in these regulatory mechanisms, and finally, speculate about the use of human trophoblastic cells as model systems for the study of a variety of cellular processes. While on one hand, human placental cells are bestowed with a capacity to proliferate indefinitely and invade extensively, on the other, these cells are also replete with mechanisms to regulate these tumor-like attributes and eventually progress to a senescent apoptotic state. This is therefore, a 'well-behaved' tumor. The comparison in the present review is between the invasive cytotrophoblastic cell type and the tumor cell type

Effect of calcium ion channel antagonists on chorionic gonadotropin secretion

By using calcium ion channel antagonists such as Verapamil and Nifedipine, we demonstrated that calcium ion channels are involved in human chorionie gonadotropin (hCG) secretion stimulated by gonadotropin releasing hormone (GnRH). Addition of 1 μM Verapamil (Class II inhibitor) resulted in an inhibition of GnRH-stimulated hCG secretion by placenta without affecting basal release. However, while addition of 10 μM Niffedipine (Class I inhibitor) resulted only in partial inhibition, significant inhibition was observed at 100 μM concentration and above. These results suggest that calcium ion channels in placenta appear to be similar although not identical with the channels reported in the pituitary

Effect of ACTH on 125I-labeled angiotensin ii binding and response by rat adrenal glomerulosa cells

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Demonstration of follicle-stimulating hormone receptor in cauda epididymis of rat

FSH receptor has been shown to be specifically expressed only in the Sertoli cells in males. In one of our studies that consisted of deprival of endogenous FSH in immature rats and adult bonnet monkeys, atrophy of the epididymis was observed, cauda region being the most affected. Although epididymis is an androgen-dependent tissue, the changes in histology of the cauda region were observed without any associated change in the levels of testosterone in FSH-deprived animals. Considering this, it was of interest to evaluate the possibility of epididymis being a direct target for FSH action. In the present study, we have examined the expression of FSH receptor in the epididymis of rat and monkey. In the cauda region of rat epididymis, FSH receptor expression was demonstrated by RT-PCR and Northern and Western blot analyses. FSH receptor was found to be functional as observed by its ability to bind 125IoFSH, by an increase in cAMP production, and by BrdU incorporation following addition of FSH under in vitro conditions. These results suggest the possibility of a role for FSH in regulating the growth of the epididymis

Various Experimental factors behind the Missing Elements in PIXE Spectrum of Charnockite Matrix

In the chemical characterization of charnokite is well investigated by using PIXE and other analytical techniques, but PIXE not given information about some of elements completely, because every technique including PIXE has proper limitations. To obtain the complete geochemical explanation of matrix charnockite composition, the experimental factors behind missing elements in PIXE at 3 MeV techniques with comparison must known and hence are used for the analysis of matrix compositions related to the earth materials like charnockite. In this study, the results obtained from PIXE compared with other analytical techniques and experimental factors of PIXE are discussed. By investigating the geochemical nature of complex charnockite material, the experimental factors which are related to the missing elements in this study of wide range of elements obtained from PIXE spectrum through the previous analytical techniques have been discussed

A solid phase radioimmunoassay for detection of early pregnancy in the South Indian bonnet monkey Macaca radiata

Using an antibody raised in the rabbit to ovine leutenizing hormone β subunit coupled to activated cellulose, a solid phase radioimmunoassay to detect early pregnancy in the South Indian bonnet monkey has been developed. Non-specific inhibition due to serum was eliminated by inclusion of new born calf serum in the assay tubes. The assay is simple, needs only one centrifugation and can be completed in 6 h at room temperature with no false positive results

Effect of human chorionic gonadotropin on serum levels of progesterone and estrogens in the pregnant bonnet monkey (Macaca radiata)

Administration of human chorionic gonadotropin to pregnant bonnet monkeys (Macaca radiata) at 55-60 days and 130-140 days of pregnancy resulted in a significant increase in serum progesterone levels. This effect could be observed even in lutectomized monkeys. However, no significant change in the serum estrogen level was noticed. These results suggest that although no chorionic gonadotropin is detectable in the serum after 35 days of pregnancy, the foetoplacental steroidogenic system is still responsive to exogenous gonadotropic stimulation

Serum concentrations of chorionic gonadotrophin, oestradiol-17β and progesterone during early pregnancy in the south Indian bonnet monkey (Macaca radiata)

Serum concentrations of chorionic gonadotrophin (CG) during early pregnancy in the bonnet monkey (Macaca radiata), were determined by a radioimmunoassay validated for measuring monkey chorionic gonadotrophin. The earliest time at which CG could be detected was on the 28th day of a fertile cycle and it could not be detected beyond the 50th day. During a fertile cycle, mean values of oestradiol-17β in addition to exhibiting a preovulatory peak around Days 9-10 of cycle, exhibited a secondary peak around Day 30 of the cycle. Serum progesterone levels remained elevated throughout the period of study from Day 18 to Day 50 and at no time did the levels fall below 2 ng/ml