56 research outputs found
Evaluation of Cell Types for Assessment of Cytogenetic Damage in Arsenic Exposed Population
Background: Cytogenetic biomarkers are essential for assessing environmental exposure, and
reflect adverse human health effects such as cellular damage. Arsenic is a potential clastogen and
aneugen. In general, the majority of the studies on clastogenic effects of arsenic are based on
frequency of micronuclei (MN) study in peripheral lymphocytes, urothelial and oral epithelial cells.
To find out the most suitable cell type, here, we compared cytogenetic damage through MN assay
in (a) various populations exposed to arsenic through drinking water retrieved from literature
review, as also (b) arsenic-induced Bowen's patients from our own survey.
Results: For literature review, we have searched the Pubmed database for English language journal
articles using the following keywords: "arsenic", "micronuclei", "drinking water", and "human" in
various combinations. We have selected 13 studies consistent with our inclusion criteria that
measured micronuclei in either one or more of the above-mentioned three cell types, in human
samples. Compared to urothelial and buccal mucosa cells, the median effect sizes measured by the
difference between people with exposed and unexposed, lymphocyte based MN counts were found
to be stronger. This general pattern pooled from 10 studies was consistent with our own set of
three earlier studies. MN counts were also found to be stronger for lymphocytes even in arsenicinduced
Bowen's patients (cases) compared to control individuals having arsenic-induced noncancerous
skin lesions.
Conclusion: Overall, it can be concluded that MN in lymphocytes may be superior to other
epithelial cells for studying arsenic-induced cytogenetic damage
Structural basis of synthetic agonist activation of the nuclear receptor REV-ERB
The nuclear receptor REV-ERB plays an important role in a range of physiological processes. REV-ERB behaves as a ligand-dependent transcriptional repressor and heme has been identified as a physiological agonist. Our current understanding of how ligands bind to and regulate transcriptional repression by REV-ERB is based on the structure of heme bound to REV-ERB. However, porphyrin (heme) analogues have been avoided as a source of synthetic agonists due to the wide range of heme binding proteins and potential pleotropic effects. How non-porphyrin synthetic agonists bind to and regulate REV-ERB has not yet been defined. Here, we characterize a high affinity synthetic REV-ERB agonist, STL1267, and describe its mechanism of binding to REV-ERB as well as the method by which it recruits transcriptional corepressor both of which are unique and distinct from that of heme-bound REV-ERB
Restoration of uterine redox-balance by methanolic extract of Camellia sinensis in arsenicated rats
Arsenic, an environmental and industrial pollutant causes female reproductive disturbances and female infertility. Several researchers found that the use of Camellia sinensis (CS) (green tea) is effective as an alternative therapeutic strategy in the management of several health ailments. This study explores the role of CS extract against arsenic-induced rat uterine tissue damage. Methanolic extract of CS (10 mg/kg BW) was tested concomitantly in arsenic-treated (10 mg/kg BW) rats for a duration of two-oestrous cycle length (8 days). CS effectively attenuated arsenic-induced antioxidantdepletion and necrosis in uterine tissue. Rats treated with sodium arsenite showed significantly
reduced activities of enzymatic antioxidants like superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) in uterine tissue as evidenced by the results of spectrophotometric and electrozymographic analysis. Co-administration of CS significantly reversed the above oxidative stress markers in uterine tissue along with the histopathological changes in ovarian and uterine tissue. Moreover, an increase in the level of transcription factor NF-ÎșB in the uterine tissue in association with reduced serum levels of vitamin B12 and folic acid were mitigated in arsenic fed rats following CSÂ co-administration
Early stages of growth of Si nanowires by metal assisted chemical etching: a scaling study
We have studied the kinetic roughening in the growth of Si nanowires (NWs) by metal assisted chemical etching (MACE) process as a function of the etching time using atomic force microscopy imaging. In the early stage of growth of Si NWs by Ag assisted MACE process, we have determined the scaling exponents α, ÎČ, and 1/z. In the formation of Si NWs, nascent Ag+ ions play an important role in diffusing through the Si surface by means of excess holes that control the size of the NWs. In this system, kinetic roughening of the growth front within the detectable range of lengths of Si NWs was observed. We have observed an αâ=â0.74â±â0.01 at the early stage of growth of Si NWs. Interface width w increases as a power law of etching time (t), wâŒtÎČ, with growth exponent ÎČâ=â0.30â±â0.05 and lateral correlation length Ο grows as ΟâŒt1/z with 1/zâ=â0.32â±â0.05. These exponents α, ÎČ, and 1/z determine the universality class in which the system belongs to. The growth mechanism is explained by conventional shadowing instability model, which is common for columnar type of surface growth
Quantitative analysis of the phonon confinement effect in arbitrarily shaped Si nanocrystals decorated on Si nanowires and its correlation with the photoluminescence spectrum
Arrays of singleâcrystalline Si nanowires (NWs) decorated with arbitrarily shaped Si nanocrystals (NCs) are grown by a metalâassisted chemical etching process using silver (Ag) as the noble metal catalyst. The metalâassisted chemical etchingâgrown Si NWs exhibit strong photoluminescence (PL) emission in the visible and near infrared region at room temperature. Quantum confinement of carriers in the Si NCs is believed to be primarily responsible for the observed PL emission. Raman spectra of the Si NCs decorated on Si NWs exhibit a red shift and an asymmetric broadening of firstâorder Raman peak as well as the other multiâphonon modes when compared with that of the bulk Si. Quantitative analysis of confinement of phonons in the Si NCs is shown to account for the measured Raman peak shift and asymmetric broadening. To eliminate the laser heating effect on the phonon modes of the Si NWs/NCs, the Raman measurement was performed at extremely low laser power. Both the PL and Raman spectral analysis show a logânormal distribution for the Si NCs, and our transmission electron microscopy results are fully consistent with the results of PL and Raman analyses. We calculate the size distribution of these Si NCs in terms of mean diameter (D0) and skewness (Ï) by correlating the PL spectra and Raman spectra of the asâgrown Si NCs decorated on Si NWs
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