Unaltered metabolism of taurolithocholic acid with changes in composition of rat intestinal microflora

Changes in composition of both total aerobes and anaerobes of rat intestinal microflora do not appear to affect the metabolism of taurolithocholic acid.     

Characteristics of patients aged over 75 not seen during one year in general practice.

A study was carried out in two large urban practices to determine the number of patients aged over 75 years who had had no contact with the primary care team during one year and to examine their medical and social characteristics. Although their general health was considered to be good, over half needed treatment or other action and half had no identifiable career.     

Isolation and characteristics of the biological and genetic properties of neamin-resistant mutants of Salmonella typhimurium and Salmonella dublin candidates for vaccine creation

Mutants, resistant to neamine and spectinomycin, have been isolated from S. typhimurium and S. dublin highly virulent strains. The neamine-resistant mutants can be divided into 3 classes in accordance with their sensitivity to streptomycin: sensitive, resistant to low and high concentrations of this antibiotic. The transduction analysis with the use of bacteriophage P 22 has revealed that the spectinomycin-resistant mutations under study are spc A mutations, while the mutations leading to resistance to neamine in class Near Strr 500 are nea B mutations. The mutation leading to resistance to spectinomycin (spc A) has been found to produce no changes in the virulence of salmonellae in the intraperitoneal infection of mice. The mutations leading to resistance to neamine and streptomycin (nea B and str A) have been found to decrease virulence.     

The effect of hepatoprotectors on lipid metabolism in CCl4-hepatitis

The hepatoprotective agents, silybinin and essentiale, were shown to prevent the development of lipid metabolism disturbances in the liver and serum of rats with CCl4-hepatitis. Slow accumulation of triglycerides, lysophosphatidylcholine and cardiolipin was observed in animals treated with these drugs, while phosphatidylcholine liver level remained high. Silybinin and essentiale inhibited the production of lipid hydroperoxide, Shiff basis, malonic dialdehyde, intensified the function of tissue antioxidants, activated liver beta-hydroxybutyrate dehydrogenase and depressed the activation of serum phospholipase A.     

The neuropsychiatry of megaloblastic anaemia.

The neuropsychiatric states of 50 patients with vitamin B12 deficiency and 34 patients with folate deficiency presenting with megaloblastosis in a general hospital were examined and compared. Abnormalities of the nervous system were found in two-thirds of both groups. Peripheral neuropathy was the most common condition associated with vitamin B12 deficiency and affective disorder with folate deficiency. The proportions of patients with organic mental change were similar in the two groups. Subacute combined degeneration of the cord was an uncommon complication and occurred only in the patients with vitamin B12 deficiency. There was no relation between haematological and neuropsychiatric abnormalities. The neuropsychiatry of megaloblastic anaemia seen in this study of patients presenting to haematologists or general physicians contrasts with that reported previously, before haematological techniques for separating the two deficiencies were introduced.     

Influence of lipid headgroup on the specificity and exchange dynamics in lipid-protein interactions. A spin-label study of myelin proteolipid apoprotein-phospholipid complexes

The pH and salt dependences of the interaction of phosphatidic acid, phosphatidylserine, and stearic acid with myelin proteolipid apoprotein (PLP) in dimyristoylphosphatidylcholine (DMPC) recombinants have been studied by electron spin resonance spectroscopy, using spin-labeled lipids. The two-component spin-label spectra have been analyzed both by spectral subtraction and by simulation using the exchange-coupled Bloch equations to give the fraction of lipids motionally restricted by the protein and the rate of lipid exchange between the fluid and motionally restricted lipid populations. For stearic acid, phosphatidic acid, and phosphatidylserine, the fraction of motionally restricted spin-label increases with increasing pH, with pKa's of 7.7, 7.6, and ca. 9.4, respectively. The corresponding pKa's for the bulk lipid regions of the bilayer are estimated, from changes in the ESR spectra, to be 6.7, 7.4, and 11, respectively. In the dissociated state at pH 9.0, the fraction of motionally restricted component decreases with increasing salt concentration, reaching an approximately constant value at [NaCl] = 0.5-1.0 M for all three negatively charged lipids. The net decreases for stearic acid and phosphatidic acid are considerably smaller (by ca. 30%) than those obtained on protonating the two lipids, whereas for phosphatidylserine the fraction of motionally restricted lipid in high salt is reduced to that corresponding to phosphatidylcholine. For a fixed lipid/protein ratio, the on-rate for exchange at the lipid-protein interface is independent of the degree of selectivity and has a shallow temperature dependence, as expected for a diffusion-controlled process.(ABSTRACT TRUNCATED AT 250 WORDS)     

Formation of glycine and aminoacetone from L-threonine by rat liver mitochondria

Threonine is a precursor of glycine in the rat, but the metabolic pathway involved is unclear. To elucidate this pathway, the biosynthesis of glycine, and of aminoacetone, from L-threonine were studied in rat liver mitochondrial preparations of differing integrities. In the absence of added cofactors, intact mitochondria formed glycine and aminoacetone in approximately equal amounts from 20 mM L-threonine, but exogenous NAD+ decreased and CoA increased the ratio of glycine to aminoacetone formed. In intact and freeze-thawed mitochondria, the ratio of glycine to aminoacetone formed was markedly sensitive to the concentration of L-threonine, glycine being the major product at low L-threonine concentrations. Disruption of mitochondrial integrity by sonication (1 min) decreased the ratio of glycine to aminoacetone formed, and in 20000 X g supernatant fractions from sonicated (3 min) mitochondria, aminoacetone was the major product. The main non-nitogenous two-carbon compound detected when intact mitochondria catabolized L-threonine to glycine was acetate, which was probably derived from deacylation of acetyl-CoA. These results suggest that glycine formation from L-threonine in rat liver mitochondria occurred primarily by the coupled activities of threonine dehydrogenase and 2-amino-3-oxobutyrate CoA-ligase, the extent of coupling between the enzymes being dependent upon a close physical relationship and upon the flux through the dehydrogenase reaction. In vivo glycine synthesis would predominate, and aminoacetone would be a minor product.