Bacterial 7-dehydroxylation of cholic acid and allocholic acid

An obligate anaerobic organism capable of dehydroxylating cholic acid to deoxycholic acid and allocholic acid to allodeoxycholic acid was isolated from feces of the rabbit. It was a member of the bacteroides group (Gram-variable, nonsporulating anaerobes). The growth of the organism was inhibited by neomycin, 10-20 micro g/ml. The existence of this organism affords a satisfactory explanation for the development of gallstones in the cholestanol-fed rabbit and for their absence in rabbits simultaneously treated with neomycin.     

Changes in the ribonucleic acid metabolism of aging mouse tissues with particular reference to the prostate gland

1. Mouse mast-cell tumours P815 Y and HC were shown to contain glycoprotein material composed of glucosamine, galactosamine, sialic acid, galactose and mannose. 2. The major amino acids released after acid hydrolysis of Pronase-treated digests of the glycoprotein are aspartic acid, glutamic acid, serine, threonine, proline, glycine and alanine. The Pronase-digested material is not degraded in alkaline solution. 3. On incubation of mast cells with [(35)S]sulphate, heparin is the major radioactive product. However, [1-(14)C]glucosamine and d-[(14)C]glucose are incorporated largely into the glycoprotein. 4. The fate of [(35)S]sulphate-labelled and [1-(14)C]glucosamine-labelled material was studied. In each case high-molecular-weight radioactive material is released from the cells into the culture medium. The t((1/2)) of [(35)S]sulphate-labelled material in cells is 70hr. and that of [1-(14)C]-glucosamine-labelled material in cells is 40hr. 5. About 60% of the [(35)S]sulphate-labelled material is present in the mitochondrial and granular fraction. [1-(14)C]-Glucosamine-labelled material is present in both microsomal and mitochondrial and granular fractions, [(14)C]sialic acid being concentrated in the microsomal fraction.     

Wound healing in the liver with particular reference to stem cells.

The efficiency of liver regeneration in response to the loss of hepatocytes is widely acknowledged, and this is usually accomplished by the triggering of normally proliferatively quiescent hepatocytes into the cell cycle. However, when regeneration is defective, tortuous ductular structures, initially continuous with the biliary tree, proliferate and migrate into the surrounding hepatocyte parenchyma. In humans, these biliary cells have variously been referred to as ductular structures, neoductules and neocholangioles, and have been observed in many forms of chronic liver disease, including cancer. In experimental animals, similar ductal cells are usually called oval cells, and their association with impaired regeneration has led to the conclusion that they are the progeny of facultative stem cells. Oval cells are of considerable biological interest as they may represent a target population for hepatic carcinogens, and they may also be useful vehicles for ex vivo gene therapy for the correction of inborn errors of metabolism. This review proposes that the liver harbours stem cells that are located in the biliary epithelium, that oval cells are the progeny of these stem cells, and that these cells can undergo massive expansion in their numbers before differentiating into hepatocytes. This is a conditional process that only occurs when the regenerative capacity of hepatocytes is overwhelmed, and thus, unlike the intestinal epithelium, the liver is not behaving as a classical, continually renewing, stem cell-fed lineage. We focus on the biliary network, not merely as a conduit for bile, but also as a cell compartment with the ability to proliferate under appropriate conditions and give rise to fully differentiated hepatocytes and other cell types.     

The role of growth hormone in the regulation of protein metabolism with particular reference to conditions of fasting

Growth hormone (GH) has potent protein anabolic actions, as evidenced by a significant decrease in lean body mass and muscle mass in chronic GH deficiency, and vice versa in patients with acromegaly. Depending on the prevailing physiological conditions and on which tissues and which proteins are under examination, the mechanisms involved include both stimulation of protein synthesis and restriction of protein breakdown. Apart from the possible direct effects of GH on protein dynamics, a number of additional anabolic agents, such as insulin, insulin-like growth factor-I and free fatty acids (FFA), are activated. Some of the most recent studies in the field have demonstrated a decisive role of stimulation of lipolysis and high circulating levels of FFA in orchestrating the maintenance of the protein pool of the body.     

Studies on the genusArtemisia L. in North-West Himalaya with particular reference to Kashmir

Present paper deals with 20 species of the genusArtemisia occurring in the North-West Himalaya. Chromosome counts are given for 18 species (for 3 species for the first time). Two new species,A. banihalensis (A. roxburghiana agg.) andA. cashemirica (A. parviflora agg.), are described.