Inactivation of Factor VIIa by Antithrombin In Vitro,Ex Vivo and In Vivo: Role of Tissue Factor and Endothelial Cell Protein C Receptor

Recent studies have suggested that antithrombin (AT) could act as a significant physiologic regulator of FVIIa. However, in vitro studies showed that AT could inhibit FVIIa effectively only when it was bound to tissue factor (TF). Circulating blood is known to contain only traces of TF, at best. FVIIa also binds endothelial cell protein C receptor (EPCR), but the role of EPCR on FVIIa inactivation by AT is unknown. The present study was designed to investigate the role of TF and EPCR in inactivation of FVIIa by AT in vivo. Low human TF mice (low TF, ∼1% expression of the mouse TF level) and high human TF mice (HTF, ∼100% of the mouse TF level) were injected with human rFVIIa (120 µg kg⁻¹ body weight) via the tail vein. At varying time intervals following rFVIIa administration, blood was collected to measure FVIIa-AT complex and rFVIIa antigen levels in the plasma. Despite the large difference in TF expression in the mice, HTF mice generated only 40–50% more of FVIIa-AT complex as compared to low TF mice. Increasing the concentration of TF in vivo in HTF mice by LPS injection increased the levels of FVIIa-AT complexes by about 25%. No significant differences were found in FVIIa-AT levels among wild-type, EPCR-deficient, and EPCR-overexpressing mice. The levels of FVIIa-AT complex formed in vitro and ex vivo were much lower than that was found in vivo. In summary, our results suggest that traces of TF that may be present in circulating blood or extravascular TF that is transiently exposed during normal vessel damage contributes to inactivation of FVIIa by AT in circulation. However, TF’s role in AT inactivation of FVIIa appears to be minor and other factor(s) present in plasma, on blood cells or vascular endothelium may play a predominant role in this process.     

The SbcC and SbcD homologs of the cyanobacterium <Emphasis Type="Italic">Anabaena</Emphasis> sp. strain PCC7120 (Alr3988 and All4463) contribute independently to DNA repair

The ubiquitous SbcCD exonuclease complex has been shown to perform an important role in DNA repair across prokaryotes and eukaryotes. However, they have remained uncharacterized in the ancient and stress-tolerant cyanobacteria. In the cyanobacterium Anabaena sp. strain PCC7120, SbcC and SbcD homologs, defined on the basis of the presence of corresponding functional domains, are annotated as hypothetical proteins, namely Alr3988 and All4463 respectively. Unlike the presence of sbcC and sbcD genes in a bicistronic operon in most organisms, these genes were distantly placed on the chromosome in Anabaena, and found to be negatively regulated by LexA. Both the genes were found to be essential in Anabaena as the individual deletion mutants were non-viable. On the other hand, the proteins could be individually overexpressed in Anabaena with no effect on normal cell physiology. However, they contributed positively to enhance the tolerance to different DNA damage-inducing stresses, such as mitomycin C and UV- and γ-radiation. This indicated that the two proteins, at least when overexpressed, could function independently and mitigate the damage caused due to the formation of DNA adducts and single- and double-strand breaks in Anabaena. This is the first report on possible independent in vivo functioning of SbcC and SbcD homologs in any bacteria, and the first effort to functionally characterize the proteins in any cyanobacteria.     

Casein as a necessary factor in the production of stimulatory material for associative growth of lactic streptococci

Strains of Streptococcus cremoris KH and HC produced material that was stimulatory for S. cremoris R₆ in milk and in the dialyzable fraction of milk, but not in the dialysate fraction of milk, lactic acid whey, or lactose broth. The addition of casein to these latter media permitted the production of this stimulatory material to occur. Tryptone, peptone, and yeast extract could not be substituted for casein in producing the stimulatory material or in initiating associative growth in the lactic acid whey. The minimum concentration of casein required appeared to be from 2.0 to 2.5%.     

Plasmodium vivax in India

Four Plasmodium species cause malaria in humans: Plasmodium vivax is the most widespread and results in pronounced morbidity. India (population >1 billion) is a major contributor to the burden of vivax malaria. With a resurgence in interest concerning the neglected burden of vivax malaria and the completion of the P. vivax genome, it is timely to review what is known concerning P. vivax in India. The P. vivax population is highly diverse in terms of relapse patterns, drug response and clinical profiles, and highly genetically variable according to studies of antigen genes, isoenzyme markers and microsatellites. The unique epidemiology of malaria in India, where P. vivax predominates over Plasmodium falciparum, renders this location ideal for studying the dynamics of co-infection.     

c-KIT positive Gastrointestinal Stromal Tumor presenting with acute bleeding in a patient with neurofibromatosis type 1: a case report

Background

Gastrointestinal stromal tumours are rare (GIST). However, the incidence of GIST among neurofibromatosis type 1 (NF-1) patients is approximately 3.9-25%. GIST can present clinically in different ways such as abdominal pain, gastrointestinal bleeding and obstruction.

Case report

We present 51 year female patient admitted with Background of neurofibromatosis type 1 admitted with melena. OGD has been done and showed duodenitis with large volume fresh blood in distal duodenum but no obvious bleeding point. Exploratory laparotomy revealed smooth nodular masses on the serosal surface of jejunum. Small bowel resection and side-to-side anastomosis were performed. Histopathoogical examination revealed small bowel gasrointestinal stromal tumour with low risk malignant potential.

Conclusion

The incidence of GIST among neurofibromatosis type 1 (NF-1) patients is not uncommon and we should pay attention to gastrointestinal manifestation in such patients.

     

Identification of an anonymous RFLP DNA probe through multiple arbitrary amplicon profiling and its use for strain differentiation in a field isolate of cellulose-degrading Aspergillus niger

The genome of Aspergillus niger (MPS-002) was subjected to RAPD fingerprinting using none different random oligonucleotide primers. A 0.7 Kb PCR amplicon, generated by primer-3 could be used as a RFLP probe to differentiate A. niger (ATCC 16880) from A. niger (MPS-002). The probe revealed DNA polymorphism internal to two different EcoRI recognition sequences spaced apart at a distance of 0.4 Kb within a 4.0 Kb EcoRI fragment of the genome of both the strains. Localized genome mapping analysis further revealed that the 0.7 Kb RFLP probe was positioned at a distance of 2.7 Kb and 0.6 Kb from the two ends of a 4.0 Kb EcoRI fragment, respectively within the genome of the two strains of A. niger.     

Nimbolide sensitizes human colon cancer cells to TRAIL through reactive oxygen species- and ERK-dependent up-regulation of death receptors, p53, and Bax

TNF-related apoptosis-inducing ligand (TRAIL) shows promise as a cancer treatment, but acquired tumor resistance to TRAIL is a roadblock. Here we investigated whether nimbolide, a limonoid, could sensitize human colon cancer cells to TRAIL. As indicated by assays that measure esterase activity, sub-G(1) fractions, mitochondrial activity, and activation of caspases, nimbolide potentiated the effect of TRAIL. This limonoid also enhanced expression of death receptors (DRs) DR5 and DR4 in cancer cells. Gene silencing of the receptors reduced the effect of limonoid on TRAIL-induced apoptosis. Using pharmacological inhibitors, we found that activation of ERK and p38 MAPK was required for DR up-regulation by nimbolide. Gene silencing of ERK abolished the enhancement of TRAIL-induced apoptosis. Moreover, our studies indicate that the limonoid induced reactive oxygen species production, which was required for ERK activation, up-regulation of DRs, and sensitization to TRAIL; these effects were mimicked by H(2)O(2). In addition, nimbolide down-regulated cell survival proteins, including I-FLICE, cIAP-1, cIAP-2, Bcl-2, Bcl-xL, survivin, and X-linked inhibitor of apoptosis protein, and up-regulated the pro-apoptotic proteins p53 and Bax. Interestingly, p53 and Bax up-regulation by nimbolide was required for sensitization to TRAIL but not for DR up-regulation. Overall, our results indicate that nimbolide can sensitize colon cancer cells to TRAIL-induced apoptosis through three distinct mechanisms: reactive oxygen species- and ERK-mediated up-regulation of DR5 and DR4, down-regulation of cell survival proteins, and up-regulation of p53 and Bax.