Genome-wide association studies of tuberculosis in Asians identify distinct at-risk locus for young tuberculosis

Tuberculosis (TB) is one of the most devastating chronic infectious diseases, but the role of host genetics in disease development after infection in this disease remains unidentified. Genome-wide association studies (GWASs) in Thais and Japanese were carried out and separately analyzed, attempted replication, then, combined by meta-analysis were not yielding any convincing association evidences; these results suggested that moderate to high effect-size genetic risks are not existed for TB per se. Because of failure in replication attempt of the top 50 single-nucleotide polymorphisms (SNPs) identified form meta-analysis data, we empirically split TB cases into young TB case/control data sets (GWAS-T(young)=137/295 and GWAS-J(young)=60/249) and old TB case/control data sets (GWAS-T(old)=300/295 and GWAS-J(old)=123/685), re-analyzed GWAS based on age-stratified data and replicated the significant findings in two independent replication samples (young TB; Rep-T(young)=155/249, Rep-J(young)=41/462 and old TB; Rep-T(old)=212/187, Rep-J(old)=71/619). GWAS and replication studies conducted in young TB identified at-risk locus in 20q12. Although the locus is located in inter-genic region, the nearest genes (HSPEP1-MAFB) from this locus are promising candidates for TB susceptibility. This locus was also associated with anti-TNF responsiveness, drug with increased susceptibility for TB. Moreover, eight SNPs in an old TB meta-analysis and six SNPs in young TB meta-analysis provided replication evidences but did not survive genome-wide significance.These findings suggest that host genetic risks for TB are affected by age at onset of TB, and this approach may accelerate the identification of the major host factors that affect TB in human populations.     

Stability studies of saponins in Bacopa monnieri dried ethanolic extracts

Bacopa monnieri (L.) Wettst. (Brahmi) is currently used as a drug and food supplement for memory improvement. However, studies on the physical and chemical stability of the extract components, especially on the lead compound important for pre-formulation, have not yet been reported. In this study, the stabilities of the crude extract and the diluted crude extract were investigated at various temperatures using saponin glycosides, bacopaside I and bacoside A3 as markers for quantitative analysis. The stability testing of bacopaside I and bacoside A3 standard solution was performed at various temperatures and pH values. The quantity of both compounds under all conditions was analyzed using HPLC techniques. The moisture adsorption of the crude extract was determined at 5, 40, 60 and 80 degrees C at 75 % relative humidity using gravimetric methods. The results revealed that the crude extract quickly adsorbed moisture up to 54 % w/w at both 40 and 80 degrees C, while it only slowly adsorbed moisture at 5 degrees C. The amounts of intact bacopaside I and bacoside A3 in the crude extract decreased drastically at 80 degrees C, slowly at 40 and 60 degrees C, and remained unchanged at 5 degrees C during the period of investigation. Moreover, the amount of both compounds in the standard solution dropped sharply at a pH of 1.2 but slowly at pH 6.8 and 9.0, respectively. The pre-formulation data could be further used for improvement of the final product quality.     

Neuroprotective effect of Bacopa monnieri on beta-amyloid-induced cell death in primary cortical culture

Aim of the study

Bacopa monnieri (Brahmi) is extensively used in traditional Indian medicine as a nerve tonic and thought to improve memory. To examine the neuroprotective effects of Brahmi extract, we tested its protection against the beta-amyloid protein (25–35) and glutamate-induced neurotoxicity in primary cortical cultured neurons.

Materials and Methods

Neuroprotective effects were determined by measuring neuronal cell viability following beta-amyloid and glutamate treatment with and without Brahmi extract. Mechanisms of neuroprotection were evaluated by monitoring cellular oxidative stress and acetylcholinesterase activity.

Results

Our result demonstrated that Brahmi extract protected neurons from beta-amyloid-induced cell death, but not glutamate-induced excitotoxicity. This neuroprotection was possibly due to its ability to suppress cellular acetylcholinesterase activity but not the inhibition of glutamate-mediated toxicity. In addition, culture medium containing Brahmi extract appeared to promote cell survival compared to neuronal cells growing in regular culture medium. Further study showed that Brahmi-treated neurons expressed lower level of reactive oxygen species suggesting that Brahmi restrained intracellular oxidative stress which in turn prolonged the lifespan of the culture neurons. Brahmi extract also exhibited both reducing and lipid peroxidation inhibitory activities.

Conclusions

From this study, the mode of action of neuroprotective effects of Brahmi appeared to be the results of its antioxidant to suppress neuronal oxidative stress and the acetylcholinesterase inhibitory activities. Therefore, treating patients with Brahmi extract may be an alternative direction for ameliorating neurodegenerative disorders associated with the overwhelming oxidative stress as well as Alzheimer's disease.