Chemoselective Deprotection of Triethylsilyl Ethers

An efficient and selective method was developed for the deprotection of triethylsilyl (TES) ethers using formic acid in methanol (5–10%) or in methylene chloride 2–5%) with excellent yields. TES ethers are selectively deprotected to the corresponding alcohols in high yields using formic acid in methanol under mild reaction conditions. Other hydroxyl protecting groups like t-butyldimethylsilyl (TBDMS) remain unaffected.     

Targeting RET to induce medullary thyroid cancer cell apoptosis: an antagonistic interplay between PI3K/Akt and p38MAPK/caspase-8 pathways

Mutations in REarranged during Transfection (RET) receptor tyrosine, followed by the oncogenic activation of RET kinase is responsible for the development of medullary thyroid carcinoma (MTC) that responds poorly to conventional chemotherapy. Targeting RET, therefore, might be useful in tailoring surveillance of MTC patients. Here we showed that theaflavins, the bioactive components of black tea, successfully induced apoptosis in human MTC cell line, TT, by inversely modulating two molecular pathways: (i) stalling PI3K/Akt/Bad pathway that resulted in mitochondrial transmembrane potential (MTP) loss, cytochrome-c release and activation of the executioner caspases-9 and -3, and (ii) upholding p38MAPK/caspase-8/caspase-3 pathway via inhibition of Ras/Raf/ERK. Over-expression of either constitutively active myristoylated-Akt-cDNA (Myr-Akt-cDNA) or dominant-negative-caspase-8-cDNA (Dn-caspase-8-cDNA) partially blocked theaflavin-induced apoptosis, while co-transfection of Myr-Akt-cDNA and Dn-caspase-8-cDNA completely eradicated the effect of theaflavins thereby negating the possibility of existence of other pathways. A search for the upstream signaling revealed that theaflavin-induced disruption of lipid raft caused interference in anchorage of RET in lipid raft that in turn stalled phosphorylation of Ras and PI3Kinase. In such anti-survival cellular micro-environment, pro-apoptotic signals were triggered to culminate into programmed death of MTC cell. These findings not only unveil a hitherto unexplained mechanism underlying theaflavin-induced MTC death, but also validate RET as a promising and potential target for MTC therapy.     

The Contribution of Non-Conventional T Cells and NK Cells in the Mycobacterial-Specific IFNγ Response in Bacille Calmette-Guérin (BCG)-Immunized Infants

Background

The Mycobacterium bovis Bacille Calmette-Guérin (BCG) vaccine is given to >120 million infants each year worldwide. Most studies investigating the immune response to BCG have focused on adaptive immunity. However the importance of TCR-gamma/delta (γδ) T cells and NK cells in the mycobacterial-specific immune response is of increasing interest.

Methods

Participants in four age-groups were BCG-immunized. Ten weeks later, in vitro BCG-stimulated blood was analyzed for NK and T cell markers, and intracellular IFNgamma (IFNγ) by flow cytometry. Total functional IFNγ response was calculated using integrated median fluorescence intensity (iMFI).

Results

In infants and children, CD4 and CD4-CD8- (double-negative (DN)) T cells were the main IFNγ-expressing cells representing 43-56% and 27-37% of total CD3+ IFNγ+ T cells respectively. The iMFI was higher in DN T cells compared to CD4 T cells in all age groups, with the greatest differences seen in infants immunized at birth (p=0.002) or 2 months of age (p<0.0001). When NK cells were included in the analysis, they accounted for the majority of total IFNγ-expressing cells and, together with DN Vδ2 γδ T cells, had the highest iMFI in infants immunized at birth or 2 months of age.

Conclusion

In addition to CD4 T cells, NK cells and DN T cells, including Vδ2 γδ T cells, are the key populations producing IFNγ in response to BCG immunization in infants and children. This suggests that innate immunity and unconventional T cells play a greater role in the mycobacterial immune response than previously recognized and should be considered in the design and assessment of novel tuberculosis vaccines.     

Delphinidin Reduces Cell Proliferation and Induces Apoptosis of Non-Small-Cell Lung Cancer Cells by Targeting EGFR/VEGFR2 Signaling Pathways

Epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor 2 (VEGFR2) have emerged as two effective clinical targets for non-small-cell lung cancer (NSCLC). In the present study, we found that delphinidin, an anthocyanidin, present in pigmented fruits and vegetables, is a potent inhibitor of both EGFR and VEGFR2 in NSCLC cells that overexpress EGFR/VEGFR2. Using these cells, we next determined the effects of delphinidin on cell growth and apoptosis in vitro and on tumor growth and angiogenesis in vivo. Delphinidin (5-60 µM) treatment of NSCLC cells inhibited the activation of PI3K, and phosphorylation of AKT and MAPKs. Additionally, treatment of NSCLC cells with delphinidin resulted in inhibition of cell growth without having significant toxic effects on normal human bronchial epithelial cells. Specifically, treatment of NCI-H441 and SK-MES-1 cells with delphindin (5-60 µM) resulted in (i) cleavage of PARP protein, (ii) activation of caspase-3 and -9, (iii) downregulation of anti-apoptotic proteins (Bcl2, Bcl-xL and Mcl-1), (iv) upregulation of pro-apoptotic proteins (Bax and Bak), and (v) decreased expression of PCNA and cyclin D1. Furthermore, in athymic nude mice subcutaneously implanted with human NSCLC cells, delphinidin treatment caused a (i) significant inhibition of tumor growth, (ii) decrease in the expression of markers for cell proliferation (Ki67 and PCNA) and angiogenesis (CD31 and VEGF), and (iii) induction of apoptosis, when compared with control mice. Based on these observations, we suggest that delphinidin, alone or as an adjuvant to current therapies, could be used for the management of NSCLC, especially those that overexpress EGFR and VEGFR2.     

Identification of Key Contributory Factors Responsible for Vascular Dysfunction in Idiopathic Recurrent Spontaneous Miscarriage

Poor endometrial perfusion during implantation window is reported to be one of the possible causes of idiopathic recurrent spontaneous miscarriage (IRSM). We have tested the hypothesis that certain angiogenic and vasoactive factors are associated with vascular dysfunction during implantation window in IRSM and, therefore, could play a contributory role in making the endometrium unreceptive in these women. This is a prospective case-controlled study carried out on 66 women with IRSM and age and BMI matched 50 fertile women serving as controls. Endometrial expression of pro-inflammatory (IL-1β, TNF-α, IFN-γ, TGF-β1), anti-inflammatory (IL-4, -10), angiogenesis-associated cytokines (IL-2, -6, -8), angiogenic and vasoactive factors including prostaglandin E2 (PGE2), vascular endothelial growth factor (VEGF), endothelial nitric oxide synthase (eNOS), nitric oxide (NO) and adrenomedullin (ADM) were measured during implantation window by ELISA. Subendometrial blood flow (SEBF) was assessed by color Doppler ultrasonography. Multivariate analysis was used to identify the significant factor(s) responsible for vascular dysfunction in IRSM women during window of implantation and further correlated with vascular dysfunction. Endometrial expression of pro-inflammatory cytokines and PGE2 were up-regulated and anti-inflammatory and angiogenesis-associated cytokines down-regulated in IRSM women as compared with controls. Further, the angiogenic and vasoactive factors including VEGF, eNOS, NO and ADM were found to be down-regulated and SEBF grossly affected in these women. Multivariate analysis identified IL-10, followed by VEGF and eNOS as the major factors contributing towards vascular dysfunction in IRSM women. Moreover, these factors strongly correlated with blood flow impairment. This study provides an understanding that IL-10, VEGF and eNOS are the principal key components having a contributory role in endometrial vascular dysfunction in women with IRSM. Down-regulation of these factors is also associated with impaired endometrial perfusion which possibly makes the endometrium unreceptive that may eventually cause early pregnancy loss.     

Microbiota Dynamics in Patients Treated with Fecal Microbiota Transplantation for Recurrent Clostridium difficile Infection

Clostridium difficile causes antibiotic-associated diarrhea and pseudomembraneous colitis and is responsible for a large and increasing fraction of hospital-acquired infections. Fecal microbiota transplantation (FMT) is an alternate treatment option for recurrent C. difficile infection (RCDI) refractory to antibiotic therapy. It has recently been discussed favorably in the clinical and scientific communities and is receiving increasing public attention. However, short- and long-term health consequences of FMT remain a concern, as the effects of the transplanted microbiota on the patient remain unknown. To shed light on microbial events associated with RCDI and treatment by FMT, we performed fecal microbiota analysis by 16S rRNA gene amplicon pyrosequencing of 14 pairs of healthy donors and RCDI patients treated successfully by FMT. Post-FMT patient and healthy donor samples collected up to one year after FMT were studied longitudinally, including one post-FMT patient with antibiotic-associated relapse three months after FMT. This analysis allowed us not only to confirm prior reports that RCDI is associated with reduced diversity and compositional changes in the fecal microbiota, but also to characterize previously undocumented post-FMT microbiota dynamics. Members of the Streptococcaceae, Enterococcaceae, or Enterobacteriaceae were significantly increased and putative butyrate producers, such as Lachnospiraceae and Ruminococcaceae were significantly reduced in samples from RCDI patients before FMT as compared to post-FMT patient and healthy donor samples. RCDI patient samples showed more case-specific variations than post-FMT patient and healthy donor samples. However, none of the bacterial groups were invariably associated with RCDI or successful treatment by FMT. Overall microbiota compositions in post-FMT patients, specifically abundances of the above-mentioned Firmicutes, continued to change for at least 16 weeks after FMT, suggesting that full microbiota recovery from RCDI may take much longer than expected based on the disappearance of diarrheal symptoms immediately after FMT.     

Interferon and Ribavirin Combination Treatment Synergistically Inhibit HCV Internal Ribosome Entry Site Mediated Translation at the Level of Polyribosome Formation

Purpose

Although chronic hepatitis C virus (HCV) infection has been treated with the combination of interferon alpha (IFN-α) and ribavirin (RBV) for over a decade, the mechanism of antiviral synergy is not well understood. We aimed to determine the synergistic antiviral mechanisms of IFN-α and RBV combination treatment using HCV cell culture.

Methods

The antiviral efficacy of IFN-α, RBV alone and in combination was quantitatively measured using HCV infected and replicon cell culture. Direct antiviral activity of these two drugs at the level of HCV internal ribosome entry site (IRES) mediated translation in Huh-7 cell culture was investigated. The synergistic antiviral effect of IFN-α and RBV combination treatment was verified using both the CalcuSyn Software and MacSynergy Software.

Results

RBV combination with IFN-α efficiently inhibits HCV replication cell culture. Our results demonstrate that IFN-α, interferon lambda (IFN-λ) and RBV each inhibit the expression of HCV IRES-GFP and that they have a minimal effect on the expression of GFP in which the translation is not IRES dependent. The combination treatments of RBV along with IFN-α or IFN-λ were highly synergistic with combination indexes <1. We show that IFN-α treatment induce levels of PKR and eIF2α phosphorylation that prevented ribosome loading of the HCV IRES-GFP mRNA. Silencing of PKR expression in Huh-7 cells prevented the inhibitory effect of IFN-α on HCV IRES-GFP expression. RBV also blocked polyribosome loading of HCV-IRES mRNA through the inhibition of cellular IMPDH activity, and induced PKR and eIF2α phosphorylation. Knockdown of PKR or IMPDH prevented RBV induced HCV IRES-GFP translation.

Conclusions

We demonstrated both IFN-α and RBV inhibit HCV IRES through prevention of polyribosome formation. The combination of IFN-α and RBV treatment synergistically inhibits HCV IRES translation via using two different mechanisms involving PKR activation and depletion of intracellular guanosine pool through inhibition of IMPDH.     

Association of Weather and Anthropogenic Factors for Transmission of Japanese Encephalitis in an Endemic Area of India

Weather and anthropogenic factors are important determinants for Japanese encephalitis (JE) transmission. During 2008–2010, an increasing trend of JE was observed in Dibrugarh district of Northeast India. The JE cases were found to be clustered between June to October in each year. Monthly minimum temperature and rainfall were significantly associated with JE transmission at 1 and 2 months lagged. However, the relationship was more prominent at a lag of 1 month than that of two. Regression analysis suggested that rainfall, minimum and maximum temperature, and relative humidity at 6:00 h are significant predictors (P < 0.05) of quarterly occurrence of JE cases. Additional anthropogenic risk factors including the conditions such as pig sty/cattle shed around and lower part of the houses and proximity of rice field to the dwelling houses (P < 0.05) were also found to be predictors for JE occurrence. Meteorological and anthropogenic risk factors can be used to forecast JE outbreaks in Assam which in turn can help the local health authorities to protect communities in JE prone areas.