Hepatitis B surface antigen carrier state in hepatosplenic schistosomiasis

The prevalence of hepatitis B surface antigen (HBsAg) was studied in 103 cases of hepatosplenic schistosomiasis (HSS), 134 control cases with a variety of illnesses including hepatointestinal schistosomiasis, and 600 blood donors, in an area endemic for both schisfosomiasis and viral hepatitis. The patients with HSS proved to be persistent carriers for HBsAg in a significantly higher proportion than the other two groups of cases. The HSS cases who were carriers of HBsAg had more clinical signs of chronic liver disease and strikingly more chronic inflammation of the portal spaces on liver biopsy. It is suggested that abnormal immunological responses in patients with HSS makes them more susceptible to become carriers of HBsAg and that the addition of this injurious factor makes their basic disease worse, and may be responsible for the development of cirrhosis in some cases.     

Formation of stable shifts of systemic arterial pressure in controlled experiments with feedback

Calcitonin is a peptide hormone secreted by C-cells which, in humans, are found mainly in the thyroid gland. It now seems that a major physiological function of this hormone in man is the long-term maintenance of the skeleton achieved by control of bone resorption. A marked sex difference in circulating calcitonin levels normally exists, with a relative deficiency in women as compared to men. It has now been found that oestrogens regulate calcitonin secretion and it appears likely that the loss of ovarian function at the menopause accelerates the natural decline in calcitonin secretion which occurs with age. Thus, post-menopausal women are more markedly calcitonin-deficient. Levels of the bone-resorbing hormones, parathyroid hormone (PTH) and 1,25 dihydroxyvitamin D are not elevated post-menopausally and it seems likely that the increased bone resorption which leads to post-menopausal bone loss is due mainly to the loss of oestrogen and calcitonin secretion.     

Chemical cross-linking of the human immunodeficiency virus type 1 Tat protein to synthetic models of the RNA recognition sequence TAR containing site-specific trisubstituted pyrophosphate analogues

A chemical ligation procedure has been developed for the synthesis of oligoribonucleotides carrying a trisubstituted pyrophosphate (tsp) linkage in place of a single phosphodiester. Good yields of tsp were obtained when a single 2'-deoxynucleoside 5' to the tsp was used in the ligation reaction. A tsp linkage was found to be reasonably stable to hydrolysis but cleaved by treatment with ethylenediamine or lysine to give phosphoamidate adducts. A model human immunodeficiency virus type 1 (HIV-1) TAR RNA duplex containing an activated tsp was able to bind to HIV-1 Tat protein with only 3-fold reduced affinity and to a Tat peptide (residues 37-72) with identical affinity compared to that of an unmodified duplex. Tsps incorporated at sites previously identified as being in close proximity to Tat protein were able to cross-link to Tat peptide (37-72) to form a covalent phosphoamidate conjugate. Endopeptidase cleavage followed by MALDI-TOF (matrix-assisted laser desorption ionization time of flight) mass spectrometric analysis provided strong evidence that a TAR duplex containing a tsp replacing the phosphate at 38-39 had reacted specifically with Lys51 in the basic region of Tat peptide (37-72). The new chemical cross-linking method may be generally useful for identifying lysines in close proximity to phosphates in basic RNA-binding domains of proteins.     

Comparative linkage mapping of genes on sheep chromosome 3 provides evidence of chromosomal rearrangements in the evolution of the Bovidae

Three genes--parathyroid hormone-like hormone (PTHLH), insulin-like growth factor 1 (IGF 1), and retinoic acid receptor gamma (RARG)--have been mapped to sheep (Ovis aries) chromosome 3 (OAR 3). The order and genetic distances between loci on OAR 3 are similar to those on cattle (Bos taurus) chromosome 5, as expected from their close evolutionary relationship. The OAR 3 linkage map shows conserved synteny with human chromosome 12, but there are at least two rearrangements in gene order between the species.