High prevalence of diabetes in an urban population in south India.

An urban population in a township in south India was screened for diabetes with an oral glucose tolerance test, every fifth person aged 20 and over registered at the local iron ore company''s hospital being screened. Of 678 people (346 men and 332 women) who were tested, 34 (5%; 20 men and 14 women) had diabetes and 14 (2%; 8 men and 7 women) had impaired glucose tolerance. Thirteen subjects were already known to be diabetic. Diabetes was present in 21% (37/179) of people aged over 40. The peak prevalence (41%; 7/17) was in the group aged 55-64. A family history of diabetes was present in 16 of the 34 subjects with diabetes and nine of the 15 with impaired glucose tolerance. Diabetes was significantly related to obesity in women but not in men (57% (8/14) v 5% (1/20)). The plasma glucose concentration two hours after glucose loading was correlated to body mass index, age, and income in both sexes. The prevalence of diabetes was significantly higher in subjects whose income was above the mean. When the overall prevalence of diabetes was adjusted to the age distribution of the Indians living in Southall, London, and in Fiji it increased to 10% and 9%, respectively. The prevalence of diabetes is high among urban Indians and is comparable with the high prevalence seen in migrant Indian populations.     

Deepithelialized turnover flaps in burns

Acute and chronic burns leave behind a full-thickness defect that always requires a flap cover. Such defects are common in electrical burn injuries of the limbs. This paper deals with 35 patients with full-thickness defects following burns in whom deepithelialized turnover dermis flaps and deepithelialized turnover flaps with deep fascia have been used. This flap is an extension of Hynes's reversed dermis graft and Smahel's deepithelialized turnover flap where there is a larger area of blood supply on the deeper aspect of the dermis. If a good hinge is provided for safe blood supply, such a flap settles well in the defect, and cumbersome multistaged procedures can be avoided. If there is less fatty tissue in the area of flap used, then reversed dermis flaps are ideal because split-skin graft take is good. When there is a lot of fatty tissue on the undersurface of dermis, the fascia is also included to make it a reversed fasciocutaneous flap to augment the blood supply and for better split-skin graft survival. Advantages of the procedure and complications are elaborated.     

On the mechanism of the gamma-aminobutyric acid receptor in the mammalian (mouse) cerebral cortex. Chemical kinetic investigations with a 10-ms time resolution adapted to measurements of neuronal receptor function in single cells.

The gamma-aminobutyric acidA (GABA) receptor belongs to a superfamily of proteins involved in chemical reactions that regulate signal transmission between cells of the nervous system and is the target of some of the agents most frequently used in medicine to control disorders of the central nervous system. In contrast to the nicotinic acetylcholine receptor, which initiates signal transmission and is the best characterized member of the superfamily, the GABA receptor forms anion-specific transmembrane channels and inhibits signal transmission. The chemical kinetic experiments described here, in which fast chemical reaction techniques were used, indicate that both receptor proteins may operate by the same mechanism. Also described is the use of a chemical kinetic technique with a 10-ms time resolution that we have developed for making measurements with single cells isolated from specific areas of the nervous system, in this case the cerebral cortex of embryonic mice. A flow device was used to equilibrate receptors on the cell surface with GABA, and the concentration of open transmembrane channels in the cells was then measured by recording the whole-cell currents at pH 7.2, 21-23 degrees C, and a transmembrane voltage of -70 mV. Two different receptor forms, A alpha and A beta, were detected in cerebral cortical cells. Although the ratio of A alpha to A beta varied from cell to cell, on average 35% and 65% of the receptor-controlled current was associated with receptor forms A alpha and A beta, respectively. At saturating concentrations of GABA, the rate coefficients of desensitization, alpha and beta, associated with these two forms have maximal values of 4.4 and 0.7 s-1, respectively. The constants of a mechanism that accounts for the open transmembrane channels of both receptor forms were evaluated over a 50-fold range of GABA concentration. The dissociation constant of the site controlling channel opening was 40 microM for A alpha and 320 microM for A beta. The channel-opening equilibrium constant, phi-1, was 3.5 for A alpha and 20 for A beta. The evaluated constants allow one to calculate Po, the conditional probability that at a given concentration of GABA the receptor-channel is open. Po could also be determined in the presence of 100 microM GABA by an independent method in which different assumptions are made in the interpretation of the experimental results, the single-channel current-recording technique. The value of Po obtained (0.56) was in good agreement with the Po value (0.61) calculated for receptor form A alpha from chemical kinetic measurements at 100 microM GABA.(ABSTRACT TRUNCATED AT 400 WORDS)     

Characterization of the high and low affinity components of the renal Ca2(+)-Mg2+ ATPase

The purpose of this study was to characterize the interrelationship between free calcium (Ca2+) and magnesium (Mg2+) in the Ca2+ ATPase enzyme cycle of kidney membranes. Experiments were performed with basolateral membranes from rat renal cortex and microdissected proximal and distal tubules from mice. Results were similar in the three types of preparations. We first investigated the effect of ATP concentration on Ca2(+)- and Mg2(+)-dependent ATP hydrolysis. With 0.2 microM Ca2+, the enzyme activity, as a function of ATP concentration, showed two saturable components: a high affinity component with a Km of 33 microM ATP and a low affinity component with a Km of 0.63 mM ATP. These components may represent either two distinct sites of ATP binding or two forms of the same site. For the sake of simplicity, it was assumed that the two components correspond to a high affinity and a low affinity substrate site. At the high affinity site (ATP = 50 microM), the Ca2+ dependence of ATP hydrolysis followed a single Michaelis-Menten kinetics with Km for Ca2+ of 0.08 microM. The addition of 1 mM Mg2+ resulted in a relatively constant increase in ATP hydrolysis at all Ca2+ concentrations, indicating that the effects of the two cations were additive. With high ATP concentration (ATP = 3 mM), Ca2+ also induced an ATP hydrolysis according to a saturable process, with a Km for Ca2+ of 0.2 microM. In contrast with what occurred with low concentrations of ATP, addition of millimolar Mg2+ completely curtailed the sensitivity of the enzyme to Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lipids and lipoprotein profile in doxorubicin treated rats: influence of alpha-tocopherol administration

The effect of doxorubicin (DXR) on the levels of heart, liver and plasma lipids and plasma lipoproteins were studied in rats. Rats were treated with DXR (2.5 mg/kg body weight weekly for 8 weeks, iv) with or without alpha-tocopherol (alpha-TPL) (400 mg/kg body wt daily for 60 days) co-administration. DXR treated rats showed increase in plasma total cholesterol, triglycerides and phospholipids. The activities of lecithin cholesterol-acyl transferase and hepatic and extrahepatic lipoprotein lipase were lowered significantly with concomitant increase in liver and heart lipid peroxide levels in DXR treatment. HDL cholesterol level was found to be decreased significantly in DXR treated rats as a result of which there was an increase of LDLc/HDLc ratio. alpha-TPL coadministration brought back the enzyme activity to near normal and reduced the level of lipid peroxides. The lipid changes were minimum in rats treated with both alpha-TPL and DXR. This study suggests that the toxicity of DXR is reflected in lipids and lipoprotein profile.     

Characterization of ATP-dependent Ca2+ transport in the basolateral membrane vesicles from proximal and distal tubules of the rabbit kidney

Basolateral membrane vesicles were prepared from purified proximal and distal tubules of the rabbit kidney. The properties of the ATP-dependent Ca2+ transport were investigated. In both membranes, there was a high affinity, ATP-dependent Ca2+ transport system (Km = 0.1 microM). The optimal concentration of Mg2+ was 0.5 mM and the optimal concentration of ATP was 1 mM. The nucleotide specificity and pH dependence of the Ca2+ transport in both membranes were similar. In basolateral membrane vesicles, calmodulin had no effect on Ca2+ transport. However, in basolateral membrane vesicles depleted of calmodulin, exogenous calmodulin increased the Ca2+ transport by increasing maximal velocity. There were no major differences in the properties of the ATP-dependent Ca2+ transport system in these two membranes. These findings are discussed in relation to why parathyroid hormone differentially modulates Ca2+ transport in these two segments of the nephron.     

STUDIES ON MEVALONATE KINASE, PHOSPHOMEVALONATE KINASE AND PYROPHOSPHOMEVALONATE DECARBOXYLASE IN DEVELOPING RAT BRAIN

Abstract— We have in the present study investigated the properties of mevalonate kinase, phosphomevalonate kinase and pyrophosphomevalonate decarboxylase in the 105,000 g supernatant fractions from rat brain, and determined whether the activities of these enzymes change during brain development. All three enzymes in brain showed a specific requirement for ATP for optimal activity. The presence of Mg²⁺ as divalent cation was also required for optimal activity of mevalonate kinase and phosphomevalonate kinase. Both Mg²⁺ and Mn²⁺ were equally effective divalent metal ions for pyrophosphomevalonate decarboxylase in brain. Mevalonate kinase as well as phosphomevalonate kinase were active in a broad pH range of 6.5–8 while the pH curve for pyrophosphomevalonate decarboxylase showed a peak activity at approx 6. No age-dependent change occurred in the activities of mevalonate kinase and phosphomevalonate kinase in developing brain, whereas pyrophosphomevalonate decarboxylase activity in brain increased during the 1st week after birth, reached a peak value at about the 8th day of age and declined slowly thereafter. The K_m for brain mevalonate kinase in 2, 13 and 52 day old rats were 312, 400 and 434 μM, respectively. The V _max for the kinase in 2, 13 and 52 day old rats were in the range of 45–52 nmol/h/mg protein, respectively. This suggests that, like in liver (R amachandran & S hah , 1976), pyrophosphomevalonate decarboxylase in brain may also be one regulatory step for cholesterol synthesis.     

C-glycosylflavones from parkinsonia aculeata

The only C-glycosylflavones isolated from Parkinsonia aculeata leaves were identified as orientin (instead of epiorientin), isoorientin (instead of parkinsonin-A), vitexin and isovitexin (instead of parkinsonin-B). Orientin was definitely present in the laevorotatory form.     

Does bovine growth hormone possess rapid lipolytic activity?

The growth promoting and rapid lipolytic activity associated with bovine growth hormone can be separated by chromatography on QAE Sephadex A-25. The contaminant responsible for the lipolytic effect was identified as bovine thyroid-stimulating hormone.