Status of B-vitamins and homocysteine in diabetic retinopathy: association with vitamin-B12 deficiency and hyperhomocysteinemia

Diabetic retinopathy (DR) is a common cause of blindness. Although many studies have indicated an association between homocysteine and DR, the results so far have been equivocal. Amongst the many determinants of homocysteine, B-vitamin status was shown to be a major confounding factor, yet very little is known about its relationship to DR. In the present study, we, therefore, investigated the status of B-vitamins and homocysteine in DR. A cross-sectional case-control study was conducted with 100 normal control (CN) subjects and 300 subjects with type-2 diabetes (T2D). Of the 300 subjects with T2D, 200 had retinopathy (DR) and 100 did not (DNR). After a complete ophthalmic examination including fundus fluorescein angiography, the clinical profile and the blood levels of all B-vitamins and homocysteine were analyzed. While mean plasma homocysteine levels were found to be higher in T2D patients compared with CN subjects, homocysteine levels were particularly high in the DR group. There were no group differences in the blood levels of vitamins B1 and B2. Although the plasma vitamin-B6 and folic acid levels were significantly lower in the DNR and DR groups compared with the CN group, there were no significant differences between the diabetes groups. Interestingly, plasma vitamin-B12 levels were found to be significantly lower in the diabetes groups compared with the CN group; further, the levels were significantly lower in the DR group compared with the DNR group. Higher homocysteine levels were significantly associated with lower vitamin-B12 and folic acid but not with other B-vitamins. Additionally, hyperhomocysteinemia and vitamin-B12 deficiency did not seem to be related to subjects' age, body mass index, or duration of diabetes. These results thus suggest a possible association between vitamin-B12 deficiency and hyperhomocysteinemia in DR. Further, the data indicate that vitamin-B12 deficiency could be an independent risk factor for DR.     

The isolation and characterization of β-glucogallin as a novel aldose reductase inhibitor from Emblica officinalis

Diabetes mellitus is recognized as a leading cause of new cases of blindness. The prevalence of diabetic eye disease is expected to continue to increase worldwide as a result of the dramatic increase in the number of people with diabetes. At present, there is no medical treatment to delay or prevent the onset and progression of cataract or retinopathy, the most common causes of vision loss in diabetics. The plant Emblica officinalis (gooseberry) has been used for thousands of years as a traditional Indian Ayurvedic preparation for the treatment of diabetes in humans. Extracts from this plant have been shown to be efficacious against the progression of cataract in a diabetic rat model. Aldose reductase (ALR2) is implicated in the development of secondary complications of diabetes including cataract and, therefore, has been a major drug target for the development of therapies to treat diabetic disease. Herein, we present the bioassay-guided isolation and structure elucidation of 1-O-galloyl-β-D-glucose (β-glucogallin), a major component from the fruit of the gooseberry that displays selective as well as relatively potent inhibition (IC(50) = 17 μM) of AKR1B1 in vitro. Molecular modeling demonstrates that this inhibitor is able to favorably bind in the active site. Further, we show that β-glucogallin effectively inhibits sorbitol accumulation by 73% at 30 μM under hyperglycemic conditions in an ex-vivo organ culture model of lenses excised from transgenic mice overexpressing human ALR2 in the lens. This study supports the continued development of natural products such as β-glucogallin as therapeutic leads in the development of novel therapies to treat diabetic complications such as cataract.     

Paradoxical role of C1561T glutamate carboxypeptidase II (GCPII) genetic polymorphism in altering disease susceptibility

Although olfaction could play a crucial role in underwater habitats by allowing fish to sense a variety of nonvolatile chemical signals, the importance of olfaction in species-rich cichlids is still controversial. In particular, examining whether cichlids rely on olfaction for reproduction is of primary interest to understand the mechanisms of speciation. In the present study, we explored the V1R (also known as ora) genes, which are believed to encode reproductive pheromone receptors in fish, in the genomes of Lake Victoria cichlids. By screening a bacterial artificial chromosome library, we identified all six intact V1R genes (V1R1 to V1R6) that have been reported in other teleost fish. Furthermore, RT-PCR and in situ hybridization analyses showed that all of the V1R genes were expressed in the olfactory epithelium, indicating that these receptors are functional in cichlids. These observations indicate that cichlids use V1R-mediated olfaction in some ways for their social behaviors.     

High viral load in the cerebrospinal fluid and brain correlates with severity of simian immunodeficiency virus encephalitis

AIDS dementia and encephalitis are complications of AIDS occurring most frequently in patients who are immunosuppressed. The simian immunodeficiency virus (SIV) model used in this study was designed to reproducibly induce AIDS in macaques in order to examine the effects of a neurovirulent virus in this context. Pigtailed macaques (Macaca nemestrina) were coinoculated with an immunosuppressive virus (SIV/DeltaB670) and a neurovirulent molecularly cloned virus (SIV/17E-Fr), and more than 90% of the animals developed moderate to severe encephalitis within 6 months of inoculation. Viral load in plasma and cerebrospinal fluid (CSF) was examined longitudinally to onset of AIDS, and viral load was measured in brain tissue at necropsy to examine the relationship of systemic and central nervous system (CNS) viral replication to the development of encephalitis. In all animals, plasma viral load peaked at 10 to 14 days postinfection and remained high throughout infection with no correlation found between plasma viremia and SIV encephalitis. In contrast, persistent high levels of CSF viral RNA after the acute phase of infection correlated with the development of encephalitis. Although high levels of viral RNA were found in the CSF of all macaques (six of six) during the acute phase, this high level was maintained only in macaques developing SIV encephalitis (five of six). Furthermore, the level of both viral RNA and antigen in the brain correlated with the severity of the CNS lesions. The single animal in this group that did not have CNS lesions had no detectable viral RNA in any of the regions of the brain. The results substantiate the use of CSF viral load measurements in the postacute phase of SIV infection as a marker for encephalitis and CNS viral replication.     

8-Quinolinamines conjugated with amino acids are exhibiting potent blood-schizontocidal antimalarial activities

Alanine, lysine, ornithine and valine conjugated to primaquine and other 8-quinolinamine antimalarials were prepared for blood-schizontocidal antimalarial activity evaluation. The analogues were examined in vivo against Plasmodium berghei (drug-sensitive strain) and Plasmodium yoelii nigeriensis (highly virulent multi-drug-resistant strain) infected mice models. N(1)-[4-(5-Butoxy-4-ethyl-6-methoxy-8-quinolylamino)pentyl]-(2S)-2,6-diaminohexanamide (20) which showed curative activity at 5mg/kg in the P. berghei test emerged as the most effective compound. N(1)-[4-(4-Ethyl-5-hexoxy-6-methoxy-8-quinolylamino)pentyl]-(2S)-2,6-diaminohexanamide (22) exhibited curative activity at 50mg/kg against P. yoelii nigeriensis in mice and emerged as the most potent analogue against multi-drug resistant strain. The results of this study represent development of highly potent 8-quinolinamines for antimalarial drug development.     

Protective immune response to 16 kDa immunoreactive recombinant protein encoding the C-terminal VP1 portion of Foot and Mouth Disease Virus type Asia 1.

Recombinant protein of Foot and Mouth Disease Virus (FMDV) type Asia 1 corresponding to the C-terminal half of VP1 was expressed in Escherichia coli. As an alternative to the synthetic peptide, this selected C-terminal region was used as a protein vaccine in guinea pigs in order to study the immune response with various adjuvant formulations: immune stimulatory complexes (ISCOMs), Montanide ISA 206, Freund's incomplete adjuvant (FIA), lipopolysaccharide (LPS) and cytokine mixture. A primary dose of 40 microg/animal followed by a booster of the same dose was injected after a 21-day interval. The sera were collected at intervals of 21, 42 and 63 days after the booster. The humoral response to vaccine was monitored by sandwich enzyme-linked immunosorbent assay (ELISA) and a serum neutralization test (SNT). The guinea pig sera showed high titers both in ELISA and SNT, which could be protective. Further, irrespective of the adjuvant preparation used, the vaccine conferred protection against the challenge virus 105 days post-vaccination in 13 of 15 animals (86%). The results indicated that a combination of recombinant protein ISCOMs and Montanide ISA 206 would be a better choice for achieving early protective titers and longer lasting immunity and that the C-terminal half of the VP1 protein may be tried as a safe vaccine for secondary immunization.     

Synthesis and evaluation of 4′,5′-dihydrospiro[piperidine-4,7′-thieno[2,3-c]pyran] analogues against both active and dormant Mycobacterium tuberculosis

Need for new drugs to fight against tuberculosis (TB) is increasing day by day. In the present work we have taken a spiro compound (GSK 2200150A) reported by GSK as a lead and we modified the structure of the lead to study the antitubercular activity. For structure activity profiling twenty-one molecules have been synthesized, characterized and evaluated for their antimycobacterial potency against both active and dormant TB. Compound 06, 1-((4-methoxyphenyl)sulfonyl)-4′,5′-dihydrospiro[piperidine-4,7′-thieno[2,3-c]pyran] was found to be the most potent compound (MIC: 8.23?µM) in active TB and was less effective than the lead but more potent than standard first line drug ethambutol. It was also found to be more efficacious than Isoniazid and Rifampicin and equipotent as Moxifloxacin against dormant Mycobacterium tuberculosis (MTB). Compound 06 also showed good inhibitory potential against over expressed latent MTB enzyme lysine ε-amino transferase with an IC₅₀ of 1.04?±?0.32?µM. This compound is a good candidate for drug development owing to potential against both active and dormant stages of MTB.