Silence of the genes

The 2006 Nobel Prize in Physiology or Medicine was awarded to Andrew Fire and Craig Mello for discovering “RNA interference—genesilencing by double-stranded RNA”. The Nobel Committee at the Karolinska Institute in Sweden selected them for the award for unraveling “a fundamental mechanism for controlling the flow of genetic information” that is “already being widely used in basic science as a method to study the function of genes and may lead to novel therapies in the future”. This has been one of the fastest Nobel Prizes conferred in physiology or medicine, considering that Fire and Mello published their path-breaking article in the journal Nature in 1998, less than ten years ago. Utpal Nath is an Assistant Professor in the Department of Microbiology and Cell Biology, IISc. His laboratory is studying the genetic mechanisms of plant development. Saumitra Das is an Associate Professor in the Department of Microbiology and Cell Biology, IISc. His laboratory is interested in the translational control of cellular and viral RNA.     

Enumeration of lymphocyte subsets using flow cytometry: Effect of storage before and after staining in a developing country setting

Lymphocyte subset estimations by flow cytometry in population-based studies require transportation of samples from the field site to the laboratory. As samples arrive late in the day they have to wait overnight before being processed. The effect of two possible approaches, sample storage for 24 h before staining and immediate staining with analysis after 24 h and 48 h were evaluated. Two sets of experiments were performed with EDTA (ethylenediamine tetra-acetate) anticoagulated peripheral blood. In the first experiment, after collection, each sample was divided into two portions. One portion was stained at the time of blood collection and the other 24 h later after keeping it at room temperature (38–45°C). In the second experiment, blood samples were stained within 1–2 h. Each sample was analyzed immediately upon completion of staining process and subsequently after 24 h and 48 h of storage at 4°C. Results suggest that blood collected in EDTA can be processed using whole blood lysis method, after storage at room temperature (38–45°C) for 24 h with some but not significant alteration in T-cell subsets. Storage at 4°C after staining for 24 h results in a lesser and insignificant loss of cells or alteration of T-cell subsets and may be the method of choice.     

Biochemical markers for alcohol consumption

A variety of laboratory tests are available to assist in the diagnosis of alcohol consumption and related disorders. The levels of intake at which laboratory results become abnormal vary from person to person. Laboratory tests are particularly useful in settings where cooperativeness is suspected or when a history is not available. Several biochemical and hematological tests, such as γ-glutamyltransferase (GGT) activity, aspartate aminotransferase (AST) activity, high-density lipoprotein cholesterol (HDL-C) content of serum, and erythrocyte mean corpuscular volume (MCV) are established markers of alcohol intake. Their validity as markers is based largely on correlations with recent intake at a single time point and on decreases in elevated values when heavy drinkers abstain from alcohol. These readily available laboratory tests provide important prognostic information and should be integral part of the assessment of persons with hazardous alcohol consumption. There are several other markers with considerable potential for more accurate reflection of recent alcohol intake. These include carbohydrate deficient transferrin, β-hexosaminidase, acetaldehyde adducts and the urinary ratio of serotonin metabolites, 5-hydroxytryptophol and 5-hydroxyindoleacetic acid. These markers provide hope for more sensitive and specific aids to diagnosis and improved monitoring for intake.     

Should we use carbohydrate deficient transferrin as a marker for alcohol abusers?

Carbohydrate deficient transferrin (CDT) is one of the conventional markers for chronic alcohol consumption, is used by researchers and clinicians. A number of enzymes are affected by ethanol intake. The induction or inhibition of sialyl transferase and plasma sialidase may be involved in the CDT level elevation. An alteration of protein transport during post-translational modification could be a primary mechanism in the impairment of protein metabolism associated with chronic alcohol abuse. Transferrin being a steroid responsive protein, sex-based hormonal variations might contribute to the lower sensitivity of CDT. Varying hormonal statuses such as pregnancy, use of contraceptives, menopause/ menstrual cycle can alter iron homeostasis in women. CDT levels are markedly affected by iron homeostasis. Several CDT assay methods appeared promising, but it is not readily apparent which technique is the most accurate. Moreover, false-positive results of CDT have been reported in non-alcohol related hepatic failure and in rare conditions. Therefore clinical interpretation of CDT needs careful assessment in patients with alcohol-related or non-alcohol-related health disorders.     

Role of ethanol on aluminum induced biochemical changes on rat brain

Aluminum and alcohol, both are well-accepted neurotoxin. The plausible mechanisms for their neurotoxicity are also common. Therefore, the effect of ethanol on aluminum induced biochemical changes in rat brain is being studied. In the present study, ethanol exposure significantly affected the aluminum and protein content of brain. The activities of acid phosphatase and alkaline phosphatase were also changed. Aluminum exposure, on the other hand, contributed significantly in the alterations of aluminum content, acid phosphatase acivity and aspartate aminotransferase activity. Though ethanol co-exposure significantly influenced the aluminum load of brain, the interactions of these two neurotoxins were found to be significant only in case of acid phosphatase activity of brain. Therefore, it can be suggested that general neurotoxicity produced by aluminum is not modified by ethanol. However, the aluminum load caused by aluminum exposure, may be influenced by ethanol co-exposure.     

Oxidative stress is the primary event: Effects of ethanol consumption in brain

Damaging effects of reactive oxygen species on living systems are well documented. They include oxidative attack on vital cell constituents. Chronic ethanol administration is able to induce an oxidative stress in the central nervous system. In the present study, 16–18 week-old male albino rats of Wistar strain were exposed to different concentration of ethanol for 4 weeks. This exposure showed profound effect on body weight. Ascorbic acid level; and activities of alkaline phosphatase and aspartate transaminase in the brain are dependent on the concentration of ethanol exposure. Chronic ethanol ingestion elicits statistically significant increase in thiobarbituric acid reactive substances level and decrease in gluatathione level in the brain. It reduces superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase activities in a dose dependent manner. However, histological examination could not reveal any pathophysiological changes. Therefore, we conclude that biochemical alterations and oxidative stress related parameters respond early in alcoholism than the histopathological changes in brain.     

The triad-iodine deficiency,hyperlipidaemia, high coronary risk— in a ‘maternal-neonate’ population of rural Africa

In order to see the pattern of changes in differential serum lipid and lipoprotein fractions as a risk marker of coronary complication in paired ‘maternal—neonate’ blood samples in an iodine deficient zone, 26 pregnant women and their corresponding new born infants at term delivery from the iodine deficient Bassa region of Plateau state, Nigeria were assessed and the results were compared with those seen in a similar 44 group of women and their newborns assessed in non lodine deficient region of Jos. The serum thyroid function and lipid and lipoprotein profiles were determined by ‘ELISA’ and ‘enzymatic’ methods respectively. Urinary iodide excretion level was also measured in 14 pregnant women in Bassa, 23 pregnant women in Jos and 16 non pregnant control from Jos. Results indicate that the pregnant women assessed in Bassa were iodine deficient (P<0.01) and their thyroid status was strikingly reduced as reflected by a drop in serum level of T4/TBG ratio (P<0.01) and a rise in TSH (P<0.005) in comparison to that seen in Jos. There was marked hypertriglyceridaemia and total hypercholesterolaemia (P<0.005), with differential significant rise in LDL cholestotol fraction (P<0.005) in the women assessed in Bassa as compared to Jos. The HDL cholesterol however dropped less significantly in the group (P<0.05) with a concurrent marked rise (P<0.001) in the serum ratio of LDL cholesterol/HDL cholesterol, total cholesterol/HDL cholesterol and triglycerides/HDL cholesterol in the lodine deficient group. A similar pattern of changes were seen in the corresponding neonates in the Bassa group as compared to Jos group. It is concluded that the pregnant women and their newborn offsprings living in a longstanding environmental iodine deficiency run a higher risk of developing coronary complications than those living in non endemic region. It is striking that such newborns surrounded by a continued state of lodine deficient may at a later adult-period of life develop marked risk of coronary complication and other features of hyperlipidaemias associated with varying thyroid insufficiency and accompanied iodine deficiency disorders. Prophylaxis measures as intervention has been highlighted.