Consensus statement for implantation and follow-up of cardiac implantable electronic devices in India

Cardiac implantable electronic device (CIED) procedures are being done by many operators/centers and it is projected that this therapy will remarkably increase in India in the coming years. This document by IHRS, aims at guiding the Indian medical community in the appropriate use and method of implantation with emphasis on implanter training and center preparedness to deliver a safe and effective therapy to patients with cardiac rhythm disorders and heart failure.     

Nuclease mechanism of the avian retrovirus pp32 endonuclease.

In vivo, the inferred circular retrovirus DNA precursor to the provirus contains two long terminal repeats (LTRs) in tandem. We studied the site-specific nicking of supercoiled DNA that contains tandem copies of avian retrovirus LTR DNA in vitro by using purified avian myeloblastosis virus pp32 endonuclease, Mg2+, and viral DNA substrates containing different LTR circle junction sequences. The results confirmed our previous observation that the pp32 protein generates two nicks, one in either viral DNA strand, each 2 nucleotides from the circle junction site. The specificity of nicking by pp32 was unchanged over an eight-fold range of protein concentration and with different avian retrovirus LTR circle junction substrates. These data are consistent with models which propose a role for the endonuclease in removal of two nucleotides from the LTR termini on integration of viral DNA in vivo.     

Effect of somatostatin on renal function.

Somatostatin has profound effects on both splanchnic and portal vascular beds. The effects of intravenous somatostatin (100 micrograms/h) on urinary volume, effective renal plasma flow, and glomerular filtration rate were compared with the effects of a control infusion of physiological saline in six normal subjects. Renal plasma flow and glomerular filtration rate were measured by primed constant isotope infusions of iodine-125 iodohippurate and chromium-51 edetic acid. Urinary volume, renal plasma flow, and glomerular filtration rate were measured during 20 minute clearance periods. During the control infusion urinary volume, renal plasma flow, and glomerular filtration rate remained essentially unchanged at 254 (SEM 3) ml/20 min, 568 (5) ml/min/1.73 m2, and 110 (2) ml/min/1.73 m2 respectively. From similar basal values the infusion of somatostatin led to a rapid decrease in all three variables. After 120 minutes of infusion of somatostatin urinary volume, renal plasma flow, and glomerular filtration rate were reduced to 148 (17) ml/20 min (p less than 0.01), 422 (7) ml/min/1.73 m2 (p less than 0.001), and 93 (3) ml/min/1.73 m2 (p less than 0.05) respectively. This effect on renal function should be borne in mind whenever somatostatin is used.     

Evolutionary Analyses Suggest a Function of MxB Immunity Proteins Beyond Lentivirus Restriction

Viruses impose diverse and dynamic challenges on host defenses. Diversifying selection of codons and gene copy number variation are two hallmarks of genetic innovation in antiviral genes engaged in host-virus genetic conflicts. The myxovirus resistance (Mx) genes encode interferon-inducible GTPases that constitute a major arm of the cell-autonomous defense against viral infection. Unlike the broad antiviral activity of MxA, primate MxB was recently shown to specifically inhibit lentiviruses including HIV-1. We carried out detailed evolutionary analyses to investigate whether genetic conflict with lentiviruses has shaped MxB evolution in primates. We found strong evidence for diversifying selection in the MxB N-terminal tail, which contains molecular determinants of MxB anti-lentivirus specificity. However, we found no overlap between previously-mapped residues that dictate lentiviral restriction and those that have evolved under diversifying selection. Instead, our findings are consistent with MxB having a long-standing and important role in the interferon response to viral infection against a broader range of pathogens than is currently appreciated. Despite its critical role in host innate immunity, we also uncovered multiple functional losses of MxB during mammalian evolution, either by pseudogenization or by gene conversion from MxA genes. Thus, although the majority of mammalian genomes encode two Mx genes, this apparent stasis masks the dramatic effects that recombination and diversifying selection have played in shaping the evolutionary history of Mx genes. Discrepancies between our study and previous publications highlight the need to account for recombination in analyses of positive selection, as well as the importance of using sequence datasets with appropriate depth of divergence. Our study also illustrates that evolutionary analyses of antiviral gene families are critical towards understanding molecular principles that govern host-virus interactions and species-specific susceptibility to viral infection.     

The benefits of local depletion: The centrosome as a scaffold for ubiquitin-proteasome-mediated degradation

The centrosome is the major microtubule-organizing center in animal cells but is dispensable for proper microtubule spindle formation in many biological contexts and is thus thought to fulfill additional functions. Recent observations suggest that the centrosome acts as a scaffold for proteasomal degradation in the cell to regulate a variety of biological processes including cell fate acquisition, cell cycle control, stress response, and cell morphogenesis. Here, we review the body of studies indicating a role for the centrosome in promoting proteasomal degradation of ubiquitin-proteasome substrates and explore the functional relevance of this system in different biological contexts. We discuss a potential role for the centrosome in coordinating local degradation of proteasomal substrates, allowing cells to achieve stringent spatiotemporal control over various signaling processes.     

Epigenetic landscape correlates with genetic subtype but does not predict outcome in childhood acute lymphoblastic leukemia

Although children with acute lymphoblastic leukemia (ALL) generally have a good outcome, some patients do relapse and survival following relapse is poor. Altered DNA methylation is highly prevalent in ALL and raises the possibility that DNA methylation-based biomarkers could predict patient outcome. In this study, genome-wide methylation analysis, using the Illumina Infinium HumanMethylation450 BeadChip platform, was carried out on 52 diagnostic patient samples from 4 genetic subtypes [ETV6-RUNX1, high hyperdiploidy (HeH), TCF3-PBX1 and dic(9;20)(p11–13;q11)] in a 1:1 case-control design with patients who went on to relapse (as cases) and patients achieving long-term remission (as controls). Pyrosequencing assays for selected loci were used to confirm the array-generated data. Non-negative matrix factorization consensus clustering readily clustered samples according to genetic subgroups and gene enrichment pathway analysis suggested that this is in part driven by epigenetic disruption of subtype specific signaling pathways. Multiple bioinformatics approaches (including bump hunting and individual locus analysis) were used to identify CpG sites or regions associated with outcome. However, no associations with relapse were identified. Our data revealed that ETV6-RUNX1 and dic(9;20) subtypes were mostly associated with hypermethylation; conversely, TCF3-PBX1 and HeH were associated with hypomethylation. We observed significant enrichment of the neuroactive ligand-receptor interaction pathway in TCF3-PBX1 as well as an enrichment of genes involved in immunity and infection pathways in ETV6-RUNX1 subtype. Taken together, our results suggest that altered DNA methylation may have differential impacts in distinct ALL genetic subtypes.     

Removal of 3'-OH-terminal nucleotides from blunt-ended long terminal repeat termini by the avian retrovirus integration protein.

The avian myeloblastosis virus integration protein (IN) was capable of removing a specific set of 3'-OH-terminal nucleotides from blunt-ended long terminal repeat (LTR) substrates which resembled linear viral DNA in vivo. The 3'-OH-recessed ends map to the in vivo site of integration on linear viral DNA. The linear DNA plasmid substrate was formed by the generation of a unique DraI restriction enzyme site (TTT/AAA) at the circle junction of a 330-bp tandem LTR-LTR insert. IN preferentially released the three T nucleotides from the minus strand of the U3 LTR substrate compared with its ability to remove the three T nucleotides from the plus strand of the U5 LTR substrate. It was also observed that IN was capable of cleaving a non-LTR DNA substrate containing sequence homology to the U5 LTR terminus.     

CBL Is Frequently Altered in Lung Cancers: Its Relationship to Mutations in MET and EGFR Tyrosine Kinases

Background

Non-small cell lung cancer (NSCLC) is a heterogeneous group of disorders with a number of genetic and proteomic alterations. c-CBL is an E3 ubiquitin ligase and adaptor molecule important in normal homeostasis and cancer. We determined the genetic variations of c-CBL, relationship to receptor tyrosine kinases (EGFR and MET), and functionality in NSCLC.

Methods and Findings

Using archival formalin-fixed paraffin embedded (FFPE) extracted genomic DNA, we show that c-CBL mutations occur in somatic fashion for lung cancers. c-CBL mutations were not mutually exclusive of MET or EGFR mutations; however they were independent of p53 and KRAS mutations. In normal/tumor pairwise analysis, there was significant loss of heterozygosity (LOH) for the c-CBL locus (22%, n = 8/37) and none of these samples revealed any mutation in the remaining copy of c-CBL. The c-CBL LOH also positively correlated with EGFR and MET mutations observed in the same samples. Using select c-CBL somatic mutations such as S80N/H94Y, Q249E and W802* (obtained from Caucasian, Taiwanese and African-American samples, respectively) transfected in NSCLC cell lines, there was increased cell viability and cell motility.

Conclusions

Taking the overall mutation rate of c-CBL to be a combination as somatic missense mutation and LOH, it is clear that c-CBL is highly mutated in lung cancers and may play an essential role in lung tumorigenesis and metastasis.