Delivery systems to increase the selectivity of antibiotics in phagocytic cells

Many infectious diseases are caused by facultative organisms that are able to survive in phagocytic cells. The intracellular location of these microorganisms protects them from the host defence systems and from some antibiotics with poor penetration into phagocytic cells. One strategy used to improve the penetration of antibiotics into phagocytic cells is the use of carrier systems that deliver these drugs directly to the target cell. Delivery systems such as liposomes, micro/nanoparticles, lipid systems, conjugates, and biological carriers such as erythrocyte ghosts may contribute to increasing the therapeutic efficacy of antibiotics and antifungal agents in the treatment of infections caused by intracellular microorganisms. The main objective of this review is to analyze recent advances and current perspectives in the use of antibiotic delivery systems in the treatment of intracellular infections such as mycobacterial infections, brucellosis, salmonellosis, listeriosis, fungal infections, visceral leishmaniasis, and HIV.

Attenuation of beta-amyloid-induced toxicity by sialic-acid-conjugated dendrimers: role of sialic acid attachment

beta-Amyloid (Abeta) is the primary protein component of senile plaques in Alzheimer's disease and is believed to be associated with neurotoxicity in the disease. We and others have shown that Abeta binds with relatively high affinity to clustered sialic acid residues on cell surfaces and that removal of cell surface sialic acids attenuates Abeta toxicity. We have also shown that sialic acid functionalized dendrimeric polymers can act as mimics of cell surface sialic acid clusters and attenuate Abeta-induced neurotoxicity. In the current study, we prepared sialic-acid-conjugated dendrimers using a physiologically relevant attachment of the sialic acid to the dendrimeric termini, and evaluated the Abeta toxicity attenuation properties of the dendrimers. We compared performance of sialic-acid-conjugated dendrimeric polymers in which the sialic acid moieties were attached to dendrimeric termini via the anomeric hydroxyl group of the sialic acid, a physiological attachment, to polymers in which the attachment was made via the carboxylic acid group on the sialic acid, a non-physiological attachment. This work enhances our understanding of Abeta-cell surface binding and is a step towards the development of new classes of sequestering agents as therapeutics for the prevention of Abeta toxicity in AD.

Memory enhancing activity of Anwala churna (Emblica officinalis Gaertn.): An Ayurvedic preparation

Ayurveda means "the science of life". Ayur means "life" and Veda means "knowledge or science". It is the oldest medical system in the world. Its origins can be traced as far back as 4500 BC, to four ancient books of knowledge, (the "Vedas") and it is still officially recognized by the government of India. The present study was aimed at investigating the effects of Anwala churna (Emblica officinalis Gaertn.), an Ayurvedic preparation on memory, total serum cholesterol levels and brain cholinesterase activity in mice. Anwala churna was administered orally in three doses (50, 100 and 200 mg/kg) for fifteen days to different groups of young and aged mice. Elevated plus maze and passive avoidance apparatus served as the exteroceptive behavioral models for testing memory. Diazepam-, scopolamine- and ageing-induced amnesia served as the interoceptive behavioral models. Total serum cholesterol levels and brain cholinesterase activity also estimated. Anwala churna (50, 100 and 200 mg/kg, p.o.) produced a dose-dependent improvement in memory scores of young and aged mice. Furthermore, it reversed the amnesia induced by scopolamine (0.4 mg/kg, i.p.) and diazepam (1 mg/kg, i.p.). Interestingly, brain cholinesterase activity and total cholesterol levels were reduced by Anwala churna administered orally for 15 days. Anwala churna may prove to be a useful remedy for the management of Alzheimer's disease on account of its multifarious beneficial effects such as, memory improving property, cholesterol lowering property and anticholinesterase activity.