Does inhibin have intrinsic prolactin suppressing activity?

Evidence to demonstrate suppressive effect of inhibin on prolactin has been presented. The inhibin preparations derived from human testicular tissue, human seminal plasma and porcine follicular fluid were tested and all the three preparations were found to exhibit prolactin suppressing activity.     

Lipase catalysed esterification of isosorbide and sorbitol

Summary Supported lipozyme catalysed esterification of isosorbide and sorbitol individually with oleic acid is studied in a tubular recycle reactor which is packed with enzyme, silica gel and solid reactant. Isosorbide produces only monooleate while sorbitol produces both mono and dioleates during the reaction.     

Differences in specificity and catalytic efficiency between allozymes of esterase-4 from Drosophila mojavensis

A more than 10-fold difference in the specificity and catalytic efficiency for 1-naphthyl esters was measured between two allozymes of esterase-4 from Drosophila mojavensis. This difference is mainly caused by a difference in the affinity for the 1-naphthyl esters. The amino acid compositions of the allozymes are not significantly different, which means that the difference in primary structure is small. Small differences in primary structure generally do not result in such a large increase in catalytic efficiency and such a large shift in substrate specificity as was found in the present study.      

Effects of prostatic inhibin and thyroid releasing hormone on lipid peroxidation in rat prostate

Effects of prostatic inhibin and thyroid releasing hormone (TRH) on lipid peroxidation in rat prostate was studied in an in vitro system. It was found that both inhibited the lipid peroxidase activity thus having a protective role in the prostate.     

Development of a radioimmunoassay for human seminal plasma inhibin.

Using a homogeneous inhibin preparation from human seminal plasma with a molecular weight of about 19 000, a sensitive and specific radioimmunoassay (RIA) for inhibin has been developed. None of the purified hormones tested, such as LH, FSH and prolactin from different species, showed any cross-reaction in this RIA. Steroid hormones such as testosterone, dihydrotestosterone, oestradiol-17 beta and progesterone did not interfere with the assay. The antiserum had an affinity constant (Ka) of 2.379 X 10(9). The assay sensitivity was 10-15 ng per tube and the intra- and inter-assay coefficients of variation were 5-7% (n = 6) and 15% (n = 10) respectively. The recovery for inhibin added to the serum of a castrated man was 95-110%. Using this RIA, inhibin levels in various biological fluids and tissues were measured. Normo-spermic semen contained significantly higher levels of inhibin than did oligospermic semen. Human prostate contained a substantial quantity of inhibin. Monkey semen, rat serum, and bovine, ovine and porcine follicular fluids cross-reacted in the RIA, while ram testicular inhibin and bull semen did not do so. In developing (9-28 days of age) male rats, circulating inhibin levels showed an inverse relationship with serum FSH levels. In female rats of this age endogenous inhibin concentrations changed in parallel with those of serum FSH.     

A triple-X female with long arm deletion of one of the X-chromosomes associated with primary amenorrhoea: 47,XX, +del(X) (q27.3)

A 25-year-old phenotypic female with primary amenorrhoea was referred for chromosomal analysis. Earlier she had undergone hormonal therapy but showed no response. The secondary sex characters were of female type, with poor breast development. Laparoscopic findings revealed the presence of a very small uterus; the right ovary was found to be undeveloped and the left was absent. Cytogenetic study revealed a case of triple-X with deletion of the terminal region of the long arm of one of the X chromosomes [Xq27.3]. Among the 100 buccal mucosa cells analysed, 30 cells showed double Barr bodies. Hormonal studies using RIA technique revealed normal levels of prolactin (9.1 ng/ml), a high level of FSH and LH (135 and 61 mIU/ml) and low levels of estradiol and progesterone (12 pg/ml and 0.20 ng/ml respectively). To our knowledge, this may be the first report of a triple X with deletion of the X chromosome associated with primary amenorrhoea.