Preparation, characterization and in vitro dissolution studies of solid dispersion of meloxicam with PEG 6000

The poor solubility and wettability of meloxicam leads to poor dissolution and hence showing variations in bioavailability. The present study is aimed to increase solubility and dissolution of the drug using solid dispersion techniques. The solid binary systems were prepared at various drug concentrations (5-40%) with polyethylene glycol 6000 by different techniques (physical mixing, solvent evaporation). The formulations were characterized by solubility studies, differential scanning calorimetry, fourier transform infrared spectroscopy and in vitro dissolution rate studies. The solubility of drug increased linearly with increase in polymer concentration showing A(L) type solubility diagrams. Infrared spectroscopy studies indicated the possibility of hydrogen bonding with polymer. The differential scanning calorimetry and powder X ray diffraction demonstrated the presence of polymer as eutectica or monotectica in solid dispersion along with the physical characteristics of the drug (crystalline, amorphous or a mixture of both). The solid dispersions of the drug demonstrated higher drug dissolution rates than physical mixtures and pure meloxicam, as a result of increased wettability and dispersibility of drug in a solid dispersion system.     

Coconut water as a cheap source for the production of delta endotoxin of Bacillus thuringiensis var. israelensis, a mosquito control agent

Bacillus thuringiensis var. israelensis (B. t. i.) is being widely used in mosquito control programs. However, the large-scale production of this bacillus is expensive due to the high cost of the production medium. In this study, we attempted to develop a cost-effective medium, based on a locally available raw material namely coconut water which is available in plenty as waste product from coconut oil industry. The yield of cell mass, sporulation and mosquito larvicidal activity were studied by growing this bacterium in this waste product and in comparison with the conventional medium (NYSM). Cell mass yield of 3.1g/L, spore count of 3.4x10(11)spores/mL and mosquito larvicidal activity (LC(50)) of 14.85ng/mL (against early fourth-instar larvae of Aedes aegypti) were obtained with a 30h old culture of this bacterium grown in coconut water. This is almost similar to that obtained with NYSM medium. Hence, coconut water-based culture medium is economical for the production of B. t. i.     

Species-diagnostic polymerase chain reaction assays for Phlebotomus argentipes and Phlebotomus papatasi, vectors of Leishmania

Species-specific differences encountered in the nucleotide sequences of a highly variable region of the 18S rRNA gene were used to design a multiplex polymerase chain reaction (PCR) assay for the identification of Phlebotomus papatasi Scopoli and Phlebotomus argentipes An-nandale & Brunetti, vectors of Leishmania. This multiplex PCR assay uses a common forward primer and two reverse primers, which are specific for the two species. Amplification of a PCR product of size 788 bp indicates the presence of P. papatasi, whereas a product of size 677 bp indicates the presence of P. argentipes. The assay was found to be highly specific and sensitive.     

Supernumerary chromosomes in mosaic Turner syndrome

The finding of a supernumerary or marker chromosome in a karyotype poses difficulty in genetic counselling. The true incidence and significance of this chromosomal aberration is unknown in Malaysia. We report two patients who presented with supernumerary chromosomes in mosaic Turner syndrome.     

Liposomal drug delivery systems--clinical applications

Liposomes have been widely investigated since 1970 as drug carriers for improving the delivery of therapeutic agents to specific sites in the body. As a result, numerous improvements have been made, thus making this technology potentially useful for the treatment of certain diseases in the clinics. The success of liposomes as drug carriers has been reflected in a number of liposome-based formulations, which are commercially available or are currently undergoing clinical trials. The current pharmaceutical preparations of liposome-based therapeutic systems mainly result from our understanding of lipid-drug interactions and liposome disposition mechanisms. The insight gained from clinical use of liposome drug delivery systems can now be integrated to design liposomes that can be targeted on tissues, cells or intracellular compartments with or without expression of target recognition molecules on liposome membranes. This review is mainly focused on the diseases that have attracted most attention with respect to liposomal drug delivery and have therefore yielded most progress, namely cancer, antibacterial and antifungal disorders. In addition, increased gene transfer efficiencies could be obtained by appropriate selection of the gene transfer vector and mode of delivery.     

Antioxidant activity of Cassia fistula (Linn.) flowers in alloxan induced diabetic rats

Aqueous extract of Cassia fistula (Linn.) flowers (ACF) was screened for its antioxidant effect in alloxan induced diabetic rats. An appreciable decrease in peroxidation products viz thiobarbituric acid reactive substances, conjugated dienes, hydroperoxides was observed in heart tissues of ACF treated diabetic rats. The decreased activities of key antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione in diabetic rats were brought back to near normal range upon ACF treatment. These results suggest that ACF has got promising antioxidative activity in alloxan diabetic rats.     

Larvicidal potential of silver nanoparticles synthesized from Leucas aspera leaf extracts against dengue vector Aedes aegypti

Vector-borne diseases caused by mosquitoes are one of the major economic and health problems in many countries. The Aedes aegypti mosquito is a vector of several diseases in humans like yellow fever and dengue. Vector control methods involving the use of chemical insecticides are becoming less effective due to development of insecticides resistance, biological magnification of toxic substances through the food chain, and adverse effects on environmental quality and non-target organisms including human health. Application of active toxic agents from plant extracts as an alternative mosquito control strategy was available from ancient times. These are nontoxic, easily available at affordable prices, biodegradable, and show broad-spectrum target-specific activities against different species of vector mosquitoes. Today, nanotechnology is a promising research domain which has wide-ranging application vector control programs. The present study investigates the larvicidal potential of solvent leaf extracts of Leucas aspera and synthesized silver nanoparticles using aqueous leaf extract against fourth instar larvae of Aedes aegypti. Larvae were exposed to varying concentrations of plant extracts and synthesized AgNPs for 24 h. The results were recorded from UV–Vis spectra, x-ray diffraction (XRD), Fourier transform infrared (FT-IR), and scanning electron microscopy (SEM), and were used to characterize and support the biosynthesis of silver nanoparticles. The formation of the AgNPs synthesized from the XRD spectrum compared with Bragg reflections can be indexed to the (111) orientations, respectively, confirmed the presence of AgNPs. The FT-IR spectra of AgNPs exhibited prominent peaks at 3,447.77; 2,923.30; and 1,618.66 cm^?1. The spectra showed sharp and strong absorption band at 1,618.66 cm^?1 assigned to the stretching vibration of (NH) C═O group. The band 1,383 developed for C═C and C═N stretching, respectively, and was commonly found in the proteins. SEM analysis of the synthesized AgNPs clearly showed the clustered and irregular shapes, mostly aggregated, and having the size of 25–80 nm. Energy-dispersive x-ray spectroscopy showed the complete chemical composition of the synthesized AgNPs. In larvicidal activity, the results showed that the maximum efficacy was observed in synthesized AgNPs leaf extracts against the fourth instar larvae of A. aegypti (LC₅₀ values of 8.5632, 10.0361, 14.4689, 13.4579, 17.4108, and 27.4936 mg/l) and (LC₉₀ values of 21.5685, 93.03928, 39.6485, 42.2029, 31.3009, and 53.2576 mg/l), respectively. These results suggest that the synthesized AgNPs leaf extracts have a higher larvicidal potential as compared to crude solvent extracts thus making them an effective combination for controlling A. aegypti.