Cord Blood Levels of Toxic and Essential Trace Elements and Their Determinants in the Terai Region of Nepal: A Birth Cohort Study

The purpose of this study is to evaluate the cord blood level of toxic and trace elements and to identify their determinants in Terai, Nepal. One hundred pregnant women were recruited from one hospital in Chitwan, Nepal in 2008. The cord blood levels of toxic [lead (Pb), arsenic (As), and cadmium (Cd)], essential trace elements [zinc (Zn), selenium (Se), and copper (Cu)], demographic, socioeconomic, and behavioral variables were measured. The mean values of Pb, As, Cd, Zn, Se, and Cu in cord blood level were found as 31.7, 1.46, 0.39, 2,286, 175, and 667 μg/L, respectively. In the multivariate regression model, cord blood As levels from less educated mothers were higher than those from educated mothers (coefficient = -0.01, 95% confidence interval [CI] = -0.02-0.00). The maternal age was positively associated with the cord blood Cd level (coefficient = 0.02, 95% CI = 0.01-0.03), while it was negatively associated with the cord blood As level (coefficient = -0.01, 95% CI = -0.03--0.01). Cord blood levels of Pb, Zn, Se, and Cu were not associated with maternal age, socioeconomic status, living environment, and smoking status. As and Cd levels were relatively lower than those reported in previous studies in Asia, while the levels of Pb and the trace elements were similar. Less educated mothers are more likely to become a higher in utero As source to their fetus, and fetuses of older mothers were more likely to have higher in utero Cd exposure in Terai, Nepal.     

Biological effects of power frequency magnetic fields: Neurochemical and toxicological changes in developing chick embryos

BACKGROUND: There are several reports that indicate a linkage between exposure to power frequency (50 - 60 Hz) magnetic fields with abnormalities in the early embryonic development of the chicken. The present study was designed to understand whether power frequency electromagnetic fields could act as an environmental insult and invoke any neurochemical or toxicological changes in developing chick embryo model. METHODS: Fertilized chicken eggs were subjected to continuous exposure to magnetic fields (50 Hz) of varying intensities (5, 50 or 100 microT) for a period of up to 15 days. The embryos were taken out of the eggs on day 5, day 10 and day 15. Neurochemical (norepinephrine and 5-hydroxytryptamine) and amino acid (tyrosine, glutamine and tryptophan) contents were measured, along with an assay of the enzyme glutamine synthetase in the brain. Preliminary toxicological investigations were carried out based on aminotransferases (AST and ALT) and lactate dehydrogenase activities in the whole embryo as well as in the liver. RESULTS: The study revealed that there was a significant increase (p < 0.01 and p < 0.001) in the level of norepinephrine accompanied by a significant decrease (p < 0.01 and p < 0.001) in the tyrosine content in the brain on day 15 following exposure to 5, 50 and 100 microT magnetic fields. There was a significant increase (p < 0.001) in glutamine synthetase activity resulting in the significantly enhanced (p < 0.001) level of glutamine in the brain on day 15 (for 100 microT only). The possible mechanisms for these alterations are discussed. Further, magnetic fields had no effect on the levels of tryptophan and 5-hydroxytryptamine in the brain. Similarly, there was no effect on the activity of either aminotransferases or lactate dehydrogenase in the whole embryo or liver due to magnetic field exposure. CONCLUSIONS: Based on these studies we conclude that magnetic field-induced changes in norepinephrine levels might help explain alterations in the circadian rhythm, observed during magnetic field stress. Also, the enhanced level of glutamine can act as a contributing factor for developmental abnormalities.     

A novel inhibitor protein of N-myristoyltransferase from Escherichia coli

Myristoyl-CoA:protein N-myristoyltransferase (NMT) catalyzes the covalent attachment of myristate to the N-terminal of the glycine residue of various eukaryotic and viral proteins of diverse functions. Earlier, we have demonstrated that NMT activity is elevated in colon and gall bladder cancer. Attenuation of NMT activity may prove a novel therapeutic protocol for cancer. We report here a novel inhibitor protein of NMT being expressed in Escherichia coli cells containing the human NMT gene on increasing the incubation period from 5 to 24h. The inhibitor protein was purified by SP-Sepharose column chromatography, heat treatment, ammonium sulfate precipitation, and Superose 12 HR/30 FPLC column chromatography. The inhibitor protein had an apparent molecular mass of 10kDa by gel filtration. It inhibited human NMT in a concentration-dependent manner with 50% inhibition at 640+/-4.68nM. The inhibitor protein showed no direct interaction with myristoyl-CoA and demonstrated no demyristoylase or protease activity. Therefore, we conclude that the inhibitor protein acts directly on NMT.     

Mammalian myristoyl CoA: protein N-myristoyltransferase

Myristoyl CoA:Protein N-myristoyltransferase (NMT) is the enzyme which catalyses the covalent transfer of myristate from myristoyl CoA to the amino-terminal glycine residue of protein substrates. Although NMT is ubiquitous in eukaryotic cells, the enzyme levels and cellular distribution vary among tissues. In this article, we describe the properties of mammalian NMT(s) with reference to subcellular distribution, molecular weights, substrate specificity and the possible involvement of NMT in pathological processes. The cytosolic fraction of bovine brain contains multiple forms of NMT activity whereas bovine spleen contains only a single form. In bovine brain and spleen, the cytosol contained majority of NMT activity. In contrast, rabbit colon and rat liver NMT activity was predominantly particulate. Regional differences in NMT activity have been observed in both rabbit intestine and bovine brain. Results from our laboratory along with the existing knowledge, provide evidence for the existence of tissue specific isozymes of NMT.     

Epidemiology and molecular typing of Candida isolates from burn patients

This study, spread over a span of 2 years describes Candida infections in burn patients of an Indian hospital. A total of 220 burn patients were monitored and Candida could be isolated from 138 patients. A total of 228 different Candida species were obtained from various body locations of these patients. Species identification revealed that Candida albicans was the most predominant (45) followed by Candida tropicalis(33), Candida glabrata (13.5), C. parapsilosis (4), C. krusei (2.75) and C. kefyr (1.75). DNA fingerprinting of all C. albicans isolates was done by using CARE-2 probe. Fingerprinting analyses of all the C. albicans strains revealed that strains collected from different patients were different. It is noteworthy that patients with disseminated candidiasis had a similar, but unique strain isolated from all body locations, suggesting a possibility that commensal isolates might be turning pathogenic. Taken together, this is probably the first ever detailed survey of Candidainfections in burn patients in India and is expected to lead to better clinical management of this group of patients.     

AP endonuclease-independent DNA base excision repair in human cells

The paradigm for repair of oxidized base lesions in genomes via the base excision repair (BER) pathway is based on studies in Escherichia coli, in which AP endonuclease (APE) removes all 3' blocking groups (including 3' phosphate) generated by DNA glycosylase/AP lyases after base excision. The recently discovered mammalian DNA glycosylase/AP lyases, NEIL1 and NEIL2, unlike the previously characterized OGG1 and NTH1, generate DNA strand breaks with 3' phosphate termini. Here we show that in mammalian cells, removal of the 3' phosphate is dependent on polynucleotide kinase (PNK), and not APE. NEIL1 stably interacts with other BER proteins, DNA polymerase beta (pol beta) and DNA ligase IIIalpha. The complex of NEIL1, pol beta, and DNA ligase IIIalpha together with PNK suggests coordination of NEIL1-initiated repair. That NEIL1/PNK could also repair the products of other DNA glycosylases suggests a broad role for this APE-independent BER pathway in mammals.     

Nonlinear analysis of EEG signals at different mental states

Background  

The EEG (Electroencephalogram) is a representative signal containing information about the condition of the brain. The shape of the wave may contain useful information about the state of the brain. However, the human observer can not directly monitor these subtle details. Besides, since bio-signals are highly subjective, the symptoms may appear at random in the time scale. Therefore, the EEG signal parameters, extracted and analyzed using computers, are highly useful in diagnostics. This work discusses the effect on the EEG signal due to music and reflexological stimulation.     

A non-canonical transferable signal mediates nuclear import of simian immunodeficiency virus Vpx protein

Protein transport into the nucleus is generally considered to involve specific nuclear localization signals (NLS) though it is becoming increasingly evident that efficient and well controlled import of proteins which lack a canonical NLS also occurs in cells. Vpx, a 112 amino acid protein from human immunodeficiency virus type 2 (HIV-2) and the closely related simian immunodeficiency virus (SIV) is one such protein, which does not have an identifiable canonical NLS and is yet efficiently imported to the nuclear compartment. Here we report that Vpx protein is imported to the nucleus independently of virus-encoded cofactors. When fusions of truncated versions of Vpx with full-length beta-galactosidase (beta-Gal) were tested, the region from Vpx 61 to 80 was found to be sufficient to mediate the import of the heterologous cytoplasmic protein to the nucleus. Inactivation of Vpx NLS precluded nuclear import of Vpx and reduced virus replication in non-dividing macrophage cultures, even when functional integrase and Gag matrix proteins implicated in viral nuclear import were present. Importantly, we identified and characterized a novel type of 20 amino acid transferable nuclear import signal in Vpx that is distinct from other import signals described. In addition, we show that the minimal nuclear targeting domain identified here overlaps with helical domain III (amino acid (aa) 64-82) and the structural integrity of this helical motif is critical for the nuclear import of Vpx. Taken together, these data suggest that Vpx is imported to the nucleus via a novel import pathway that is dependent on its 20 amino acid unique nuclear targeting signal, and that the nuclear import property of Vpx is critical for the optimal virus replication in non-dividing cells such as macrophages.     

Self-stabilized CpG DNAs optimally activate human B cells and plasmacytoid dendritic cells

We recently showed that 5'-terminal secondary structures in CpG DNA affect activity significantly more than those at the 3'-end [Biochem. Biophys. Res. Commun. 306 (2003) 948]. The need for an accessible 5'-end of CpG DNA for activity suggested that the receptor reads the DNA sequence from this end. In continuation of these studies, we have designed immunomodulatory oligonucleotides (IMOs), consisting of a nine-mer stimulatory domain, containing a CpG motif and a hairpin-loop structure at the 3'-end, referred to as self-stabilized CpG DNAs. We studied the ability of self-stabilized CpG DNAs to stimulate human B-cell proliferation and interferon-alpha (IFN-alpha) secretion in plasmacytoid dendritic cell (pDC) culture assays. Self-stabilized CpG DNAs activated human B cells and induced plasmacytoid dendritic cells to secrete high levels of IFN-alpha. While both stimulatory and secondary structures in CpG DNAs were required for pDC activation, CpG motifs were sufficient to activate B cells. Interestingly, CpG motifs were not required for activity in the hairpin duplex region. Further modifications of the hairpin duplex region with a mixture of oligodeoxynucleotides and oligo-2'-O-methylribonucleotides in a heteroduplex formation permitted activation of both human B cells and pDCs.