Mitochondrial diseases: an overview of genetics, pathogenesis, clinical features and an approach to diagnosis and treatment

Defects in structures or functions of mitochondria, mainly involving the oxidative phosphorylation, mitochondrial biogenesis and other metabolic pathways have been shown to be associated with a wide spectrum of clinical phenotypes. The ubiquitous nature of mitochondria and their unique genetic features contribute to the clinical, biochemical and genetic heterogenecity of mitochondrial diseases. This article focuses on the recent advances in the field of mitochondrial disorders with respect to the consequences for an advanced clinical and genetic diagnostics. In addition, an overview on recently identified genetic defects and their pathogenic molecular mechanisms are given.     

Chromatin interactions in differentiating keratinocytes reveal novel atopic dermatitis– and psoriasis-associated genes

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Effect of sodium arsenite on peripheral lymphocytes in vitro: individual susceptibility among a population exposed to arsenic through the drinking water

Arsenic (As) contamination in ground water has affected more than 19 countries. Approximately 36 million people in the Bengal delta alone are exposed to this toxicant via drinking water (>50 microg/l) and are at potential health risk. Chronic ingestion of As via drinking water is associated with occurrence of skin lesions, cancer and other arsenic-induced diseases in West Bengal, India. An in vitro cytogenetic study was performed utilizing chromosomal aberrations (CA) in lymphocytes treated with sodium arsenite (0-5 microM) in six symptomatic (having arsenic-related skin lesions) individuals, six age- and sex-matched As-exposed asymptomatic (no arsenic-related skin lesions) individuals and six control individuals with similar socio-economic status residing in non-affected districts of West Bengal with no evidence of As exposure. The mean As content in nails and hair was 9.61 and 5.23 microg/g in symptomatic, 3.48 and 2.17 microg/g in asymptomatic and 0.42 and 0.33 microg/g in the control individuals, respectively. The main aim of our study was to determine whether genotoxic effects differed in the lymphocytes of the control (no exposure to arsenic), asymptomatic and symptomatic individuals after in vitro treatment with sodium arsenite. Although both the exposed groups had chronic exposure to As through the drinking water, individuals with skin lesions accumulated more As in their nails and hair and excreted less in urine (127.80 versus 164.15 microg/l). The results show that sodium arsenite induced a significantly higher percentage of aberrant cells in the lymphocytes of control individuals than in the lymphocytes of both the exposed groups. Within the two exposed groups As induced higher incidences of CA in the symptomatic than the asymptomatic individuals. These results suggest that asymptomatic individuals have relatively lower sensitivity and susceptibility to induction of genetic damage by As compared with the symptomatic individuals.     

Learning disabilities and school problems in a regional cohort of extremely low birth weight (less than 1000 G) children: a comparison with term controls

We compared the prevalence of learning disabilities at age 8 years in a subgroup of 68 of 129 (53%) regional cohort of extremely low birth weight (ELBW) children who were considered "normal" neurologically and intellectually (IQ greater than or equal to 85) with that of 114 term group matched controls (C). Both groups were tested with a battery of psychoeducational measures, and parents and teachers completed questionnaires on the school performance of the children. ELBW children were comparable with C on measures of intelligence (ELBW 101 +/- 8, C 104 +/- 11), language, and academic achievement but fared significantly less well in motor performance (p less than .0001). The prevalence of learning disabilities (by predefined criteria) in ELBW children (26%) was not increased compared with C (19%). However, teachers rated significantly more ELBW children as performing below grade level than were C (31% vs 16%, p less than .05), and by parent report, a higher proportion of ELBW children had received special assistance in school compared with C (37% vs 16%, p less than .001). We conclude that although the prevalence of learning disabilities in normal ELBW children was not different from that in controls, ELBW children did less well and utilized more special resources.     

Synthesis of 1,2,3-triazole tethered bifunctional hybrids by click chemistry and their cytotoxic studies

In view of the drug resistance with most of the currently used anticancer drugs, molecular hybrids of pyrazolyl chalcones and p-nitro benzyl functionalities tethered by triazole ring have been synthesised and evaluated for cytotoxic studies against three human cancer cell lines (THP, COLO-205, A-549). The results of the preliminary investigation exhibited marked dependence of the cytotoxic activity on the electronic factors. Placement of naphthyl (JGPT-11) and trimethoxy phenyl ring (JGPT-6) as ring A proved to be extremely beneficial in enhancing the cytotoxic potential. Thus we herein report the synthesis and cytotoxic studies of a new class of molecular hybrids. Detailed investigation on the biological mechanistic insights of JGPT-11 and 6 is under progress.     

Reversible electrophysiological abnormalities in hypokalemic paralysis: Case report of two cases

Compound muscle action potential (CMAP) amplitude declines during a paralytic attack in patients with hypokalemic periodic paralysis (HPP). However, serial motor nerve conduction studies in hypokalemic paralysis have not been commonly reported. We report two cases with hypokalemic paralysis, who had severely reduced CMAPs in all motor nerves at presentation during the episode of quadriparesis. However, the amplitude of CMAPs increased and reached normal levels, as the serum potassium concentration and motor power returned to normal state.