Small interfering RNA for cancer treatment: overcoming hurdles in delivery.

In many ways, cancer cells are different from healthy cells. A lot of tactical nano-based drug delivery systems are based on the difference between cancer and healthy cells. Currently, nanotechnology-based delivery systems are the most promising tool to deliver DNA-based products to cancer cells. This review aims to highlight the latest development in the lipids and polymeric nanocarrier for siRNA delivery to the cancer cells. It also provides the necessary information about siRNA development and its mechanism of action. Overall, this review gives us a clear picture of lipid and polymer-based drug delivery systems, which in the future could form the base to translate the basic siRNA biology into siRNA-based cancer therapies.

How do habitat filtering and niche conservatism affect community composition at different taxonomic resolutions?

Understanding how local species assembly depends on the regional biogeographic and environmental context is a challenging task in community ecology. In spatially implicit neutral models, a single immigration parameter, I(k), represents the flux of immigrants from a regional pool that compete with local offspring for establishment in communities. This flux counterbalances the effect of local stochastic extinctions to maintain local species diversity. If some species within the regional pool are not adapted to the local environment (habitat filtering), the migrant flux is reduced beyond that of the neutral model, such that habitat filtering influences the value of I(k) in non-neutral situations. Here, we propose a novel model in which immigrants from the regional pool are filtered according to their habitat preferences and the local environment, while taxa potentially retain habitat preferences from their ancestors (niche conservatism). Using both analytical reasoning and simulations, we demonstrate that I(k) is expected to be constant when estimated based on the community composition at several taxonomic levels, not only under neutral assumptions, but also when habitat filtering occurs, unless there is substantial niche conservatism. In the latter case, I(k) is expected to decrease when estimated based on the composition at species to genus and family levels, thus allowing a signature of niche conservatism to be detected by simply comparing I(k) estimates across taxonomic levels. We applied this approach to three rain forest data sets from South India and Central America and found no significant signature of niche conservatism when I(k) was compared across taxonomic levels, except at the family level in South India. We further observed more limited immigration in South Indian forests, supporting the hypothesis of a greater impact of habitat filtering and heterogeneity there than in Central America. Our results highlight the relevance of studying variations of I(k) in space and across taxonomic levels to test hypotheses about the ecological and evolutionary drivers of biodiversity patterns.

Hepatic tuberculosis in absence of disseminated abdominal tuberculosis.

Liver involvement in tuberculosis in absence of miliary tuberculosis is rare. This study was performed to analyse the spectrum and response to treatment of hepatic tuberculosis in the absence of miliary abdominal tuberculosis. Retrospective analysis of seven cases of hepatic tuberculosis without miliary abdominal tuberculosis who presented at the single tertiary referral center were analyzed. All patients presented with fever and hepatomegaly. Five of them had pain in upper abdomen and vomiting. HIV serology was positive in one patient. All patients had normocytic normochromic anaemia, raised erythrocyte sedimentation rate (Mean 65). Mild elevation of liver enzymes and low albumin (Mean 2.4 gm%) with reversal of albumin globulin ratio (Mean 0.6) were seen in all. Two had jaundice. Prothrombin time was normal in all and lactate dehydrogenase values were elevated in all (Mean 794 IU/L). On ultrasonography, 2 had multiple hypodense lesion, 1 had coarse echotexture of liver, 1 had hyperechoic pattern and 3 had just hepatomegaly. Complete resolution of liver lesions on treatment with 4-drug anti-tuberculosis drug chemotherapy was seen. In conclusion, liver tuberculosis has protean manifestations with nonspecific alteration of liver function tests and is best diagnosed on liver biopsy. Overall response to therapy is satisfactory.