Bioscience Reports

Quantitative X-ray microanalysis of 8 elements was performed on ultrathin, freeze-dried sections of islets and pancreas pieces from non-inbredob/ob-mice. Diffusion of elements was reduced to a minimum by rapidly freezing the tissue samples between nitrogen-cooled polished copper surfaces and avoiding the use of chemical fixatives and stains. The ultrastructural morphology was adequately maintained to allow measurements on secretory granules, mitochondria, cell nuclei, and cytoplasm free of these organelles. The distribution of the various elements between cellular compartments was similar in islet β-cells and exocrine pancreas cells. However, the insulin secretory granules were outstanding in exhibiting the highest concentrations of zinc and calcium. In comparison with cytoplasm in the β-cells, the insulin granules accumulated calcium 2-fold and zinc as much as 40-fold. As no correlation could be made for endoplasmic reticulum in the cytoplasmic measurements areas, the true accumulations above cytosol are likely to be even higher.

Vincristine (Vcr) dose dependently inhibited growth of the kidney adenocarcinoma cell line ACHN during 4 days of culture. Verapamil (Ver) at 10 μM and cyclosporin A (CsA) at 1 μg/ml had no effect on cell growth but significantly potentiated the action of Vcr, despite the absence of the multidrug resistance associated membrane P-glycoprotein (P-gp). Neither Ver nor CsA had any acute or long term effects on cytoplasmic free Ca2+ concentration (Ca2+i), except for a small Ver induced increase after 36 h of incubation. The results indicate that Ver and CsA may have a sensitizing effect on chemotherapeutic drug sensitivity also in absence of P-gp. However, these effects are probably not mediated by changes in Ca2+i.

The protonmotive force (Δp) across the mitochondrial inner membrane drives ATP synthesis. In addition, the energy stored in Δp can be dissipated by proton leak through the inner membrane, contributing to basal metabolic rate and thermogenesis. Increasing mitochondrial proton leak pharmacologically should decrease the efficiency of oxidative phosphorylation and counteract obesity by enabling fatty acids to be oxidised with decreased ATP production. While protonophores such as 2,4-dinitrophenol (DNP) increase mitochondrial proton leak and have been used to treat obesity, a slight increase in DNP concentration above the therapeutically effective dose disrupts mitochondrial function and leads to toxicity. Therefore we set out to develop a less toxic protonophore that would increase proton leak significantly at high Δp but not at low Δp. Our design concept for a potential self-limiting protonophore was to couple the DNP moiety to the lipophilic triphenylphosphonium (TPP) cation and this was achieved by the preparation of 3-(3,5-dinitro-4-hydroxyphenyl)propyltriphenylphosphonium methanesulfonate (MitoDNP). TPP cations accumulate within mitochondria driven by the membrane potential (Δψ), the predominant component of Δp. Our hypothesis was that MitoDNP would accumulate in mitochondria at high Δψ where it would act as a protonophore, but that at lower Δψ the accumulation and uncoupling would be far less. We found that MitoDNP was extensively taken into mitochondria driven by Δψ. However MitoDNP did not uncouple mitochondria as judged by its inability to either increase respiration rate or decrease Δψ. Therefore MitoDNP did not act as a protonophore, probably because the efflux of deprotonated MitoDNP was inhibited.

Chandipura virus, a member of the rhabdoviridae family and vesiculovirus genera, has recently emerged as human pathogen that is associated with a number of outbreaks in different parts of India. Although, the virus closely resembles with the prototype vesiculovirus, Vesicular Stomatitis Virus, it could be readily distinguished by its ability to infect humans. Studies on Chandipura virus while shed light into distinct stages of viral infection; it may also allow us to identify potential drug targets for antiviral therapy. In this review, we have summarized our current understanding of Chandipura virus life cycle at the molecular detail with particular interest in viral RNA metabolisms, namely transcription, replication and packaging of viral RNA into nucleocapsid structure. Contemporary research on otherwise extensively studied family member Vesicular Stomatitis Virus has also been addressed to present a more comprehensive picture of vesiculovirus life cycle. Finally, we reveal examples of protein economy in Chandipura virus life-cycle whereby each viral protein has evolved complexity to perform multiple tasks.