Vesicle formation by amphiphilic 10-alkyl-3-methyl isoalloxazine in aqueous medium.

The synthetic 10-alkyl isoalloxazines have been found to form vesicles in aqueous and binary solvent systems and confirmed by UV-visible, fluorescence,transmission electron microscopy and quasi elastic light scattering experiments. The mean external diameters of vesicles have been calculated for isoalloxazine with different carbon atom chain at position 10 by transmission electron microscopy and quasi elastic laser light scattering. The gel to liquid phase transition of liposomes measured by differential scanning calorimetry shows reproducible endothermic peak which lies well in the range of typical aqueous vesicles.

Incorporation of synthetic tetramethylene diamine 8,8'-bis(riboflavin tetraacetate) in DMPC vesicles.

The tetramethylene diamine 8,8'-bis(riboflavin tetraacetate) is synthesized by condensation of 8 alpha-bromo riboflavin tetraacetate and 1,4 diaminobutane. The incorporation of bis(riboflavin tetraacetate) in bilayer of DMPC vesicles has been studied by gel permeation chromatography, UV-visible and fluorescence spectroscopy.

Baculovirus vector-mediated expression of heterologous genes in insect cells.

The baculovirus expression system employing Autagrapha californica nuclear polyhidrosis virus and Spodoptera frugiperda insect cells in culture has proved very popular for high level expression of heterologous genes: In this system, transcription of the foreign gene is usually driven by the hyperactive and temporally regulated polyhedrin gene promoter. Replacement of the polyhedrin gene, which encodes a 29-kDa occlusion protein (non-essential for viral replication), with a gene of interest leads to an occlusion negative phenotype which serves as a visual marker to select for recombinant viruses. Simultaneous expression of multiple genes can also be achieved. The heterologous proteins synthesized in this system are antigenically, immunologically and functionally identical in most respects to their native counterparts. This mini-review will aim at summarizing the potentials and utility of the baculovirus expression vector system and will address some important questions relating to the biology of this system.

Effect of acute & chronic imipramine treatment on glucose homeostasis.

Single dose of imipramine (IMI) produced significant (P less than 0.05) hyperglycemia in rabbits, the effect peaking at 1 h. The hyperglycemic response was less marked in rabbits which were chronically pretreated with IMI for 4 wk. Simultaneous administration of insulin, oral glucose or adrenaline with single doses of IMI resulted in an enhancement of usual hypoglycemic/hyperglycemic responses of these agents. However, when these drugs were administered in chronically IMI fed animals there was complete reversion of the enhancement. Daily administration of adrenaline for further 6 days with IMI feeding in the chronically IMI treated rabbits, led to enhancement in the hyperglycemic response to adrenaline (P less than 0.001). In contrast, similar administration of insulin resulted in reduced hypoglycemia. Further, glucose feeding with IMI plus adrenaline or insulin in these animals did not result in any significant alteration in blood glucose level (BGL), as compared to oral glucose plus single doses of adrenaline or insulin. GTT done on the day next to drug treatment in rabbits chronically pretreated with IMI and than with IMI plus insulin, produced an enhanced hyperglycemic response, as compared with the control group (P less than 0.01). These observations indicate that acute (but not chronic) treatment with IMI not only produces a rise in BGL per se but also enhances the response to other agents which affect glucose homeostasis.