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Biomedical subjects

S Mitra

Publications and source records attributed to S Mitra.

At least 19 recordsLinked to original sources
PubMed2006

Interplay between human papilloma virus infection and p53 gene alterations in head and neck squamous cell carcinoma of an Indian patient population.

AIM: To investigate the complex interplay between human papilloma virus (HPV) infection and p53 gene alteration in 92 head and neck squamous cell carcinoma (HNSCC) and 28 leukoplakia samples from eastern India. METHODS: DNA isolated from the patient samples was subjected to HPV detection, loss of heterozygosity (LOH) analysis of the chromosome 17p region harbouring p53, genotyping at the p53 codon 72 locus and sequencing of the entire p53 gene to identify somatic mutations. Codon 72 heterozygotes carrying the p53 mutation were further cloned and resequenced to identify the allele harbouring the mutation. RESULTS: HPV positivity in the HNSCC samples was 69%; 21% of the HNSCC were found to harbour p53 mutations in the coding region of the gene. The absence of the p53 mutation in HPV positive tumours was statistically significant compared to the HPV negative tumours (p = 0.01), but the same did not hold true for p53 LOH (p = 1.0). Among the germline p53 codon 72 heterozygotes, the Pro allele was preferentially lost (p = 0.02) while the Arg allele was mutated in the majority of cases. The risk of HPV mediated tumourigenesis increased with the increase in number of Arg alleles at the codon 72 locus. CONCLUSION: It is proposed that genetic and epigenetic alteration of p53 follow distinct pathways during the development of HNSCC from normal epithelium via dysplasia. The p53 mutation and HPV mediated p53 inactivation possibly constitute two independent pathways of tumourigenesis.

Adult↗
PubMed2006

Diffusion of acetylene inside Na-Y zeolite: molecular dynamics simulation studies.

Dynamics of acetylene molecules adsorbed in Na-Y zeolite cages is investigated using molecular dynamics simulation. The translational motion of the acetylene molecules is shown to involve three different time scales. "Free particle" type diffusion is observed in short time and small length scale. At long time and large length scale, center of mass motion of acetylene is determined by the zeolitic pore topology. Rotational motion of the acetylene is found to be very fast. Detailed analysis of the intermediate scattering function corresponding to the rotational motion showed large-angle jumps that could be described by an m-diffusion model.

Journal Article↗
PubMed2006

High rate capabilities Fe3O4-based Cu nano-architectured electrodes for lithium-ion battery applications.

All battery technologies are known to suffer from kinetic problems linked to the solid-state diffusion of Li in intercalation electrodes, the conductivity of the electrolyte in some cases and the quality of interfaces. For Li-ion technology the latter effect is especially acute when conversion rather than intercalation electrodes are used. Nano-architectured electrodes are usually suggested to enhance kinetics, although their realization is cumbersome. To tackle this issue for the conversion electrode material Fe3O4, we have used a two-step electrode design consisting of the electrochemically assisted template growth of Cu nanorods onto a current collector followed by electrochemical plating of Fe3O4. Using such electrodes, we demonstrate a factor of six improvement in power density over planar electrodes while maintaining the same total discharge time. The capacity at the 8C rate was 80% of the total capacity and was sustained over 100 cycles. The origin of the large hysteresis between charge and discharge, intrinsic to conversion reactions, is discussed and approaches to reduce it are proposed. We hope that such findings will help pave the way for the use of conversion reaction electrodes in future-generation Li-ion batteries.

Journal Article↗
PubMed2006

A 3-year prospective study of the effects of adjuvant treatments on cognition in women with early stage breast cancer.

The neuropsychological performance of 85 women with early stage breast cancer scheduled for chemotherapy, 43 women scheduled for endocrine therapy and/or radiotherapy and 49 healthy control subjects was assessed at baseline (T1), postchemotherapy (or 6 months) (T2) and at 18 months (T3). Repeated measures analysis found no significant interactions or main effect of group after controlling for age and intelligence. Using a calculation to examine performance at an individual level, reliable decline on multiple tasks was seen in 20% of chemotherapy patients, 26% of nonchemotherapy patients and 18% of controls at T2 (18%, 14 and 11%, respectively, at T3). Patients who had experienced a treatment-induced menopause were more likely to show reliable decline on multiple measures at T2 (OR=2.6, 95% confidence interval (CI) 0.823-8.266 P=0.086). Psychological distress, quality of life measures and self-reported cognitive failures did not impact on objective tests of cognitive function, but were significantly associated with each other. The results show that a few women experienced objective measurable change in their concentration and memory following standard adjuvant therapy, but the majority were either unaffected or even improve over time.

Adult↗
PubMed2006

Fourier transform infrared and quasielectron neutron scattering studies on the binding modes of methanol molecules in the confined spaces of HMCM-41 and HZSM-5: role of pore structure and surface acid sites.

Quasielastic neutron scattering (QENS) and Fourier transform infrared spectroscopic studies were carried out on methanol molecules adsorbed in HMCM-41 and HZSM-5 molecular sieves to monitor the effect of pore structure on their occluded state under the conditions of ambient temperature and 5-250 mbar pressures. The QENS results have shown that the pore geometry of the host matrix and the dipolar character of the adsorbate are together responsible for the binding state of guest molecules in the confining medium. Thus, neither translational nor free rotational motion was noticed for methanol molecules adsorbed in HZSM-5, in contrast to benzene and cyclohexane molecules of almost similar size that are reported to undergo a rotational motion under the identical conditions of loading (Phys. Chem. Chem. Phys. 2001, 3, 4449; 2003, 5, 3066). In the case of HMCM-41, a translational motion of occluded methanol molecules was clearly observed with a diffusion constant D approximately 1.5 x 10(-5) cm2 s(-1), as compared to a value of D approximately 2.6 x 10(-5) cm2 s(-1) for its liquid state. These results indicate that the adsorbed methanol experiences a considerable extent of supercooling due to capillary condensation in zeolitic pores, giving rise to formation of a metastable state even at room temperature. In HZSM-5, entrapped methanol exists in an almost solidlike state, whereas in HMCM-41, its density lies between that of the solid and the liquid phases. Infrared spectroscopic study conducted using deuterium-labeled adsorbate and host matrixes have given evidence for different kinds of interactions between the methanol molecules and the host matrix, depending upon the loading. For small loadings the internal hydroxy groups within the pore system get perturbed first, giving rise to formation of the methoxy groups. Multilayer adsorption and capillary condensation of methanol occur for a loading of 0.05 mmol per gram and above, within the pore system and also at the external surface, giving rise to a highly compressed state due to strong intermolecular bonding. At the same time, a considerable amount of exchange occurred between the hydroxy groups of the adsorbed methanol and those of the host matrix. Such exchange of hydroxy groups may play an important role in the catalytic properties of the porous aluminosilicates.

Journal Article↗
PubMed2006

Effects of garlic oil on postmenopausal osteoporosis using ovariectomized rats: comparison with the effects of lovastatin and 17beta-estradiol.

The purpose of this study was to examine the antiosteoporosis effects of garlic oil in an ovariectomized (Ovx) rat model of osteoporosis and to compare its efficacy with lovastatin (a synthetic hypocholesterolemic drug) and 17beta-estradiol (a potent antiosteoporotic agent). Animals were divided into five groups: sham-operated control, ovariectomized, ovariectomized supplemented with lovastatin, ovariectomized supplemented with garlic oil and ovariectomized supplemented with 17beta-estradiol. In our study, the development of a high rate of bone turnover and osteoporosis in the ovariectomized animals were confirmed by significant alterations of serum alkaline phosphatase activity, serum tartrate-resistant acid phosphatase activity, urinary excretion of calcium, phosphate, hydroxyproline and urinary calcium to creatinine ratio, when compared with the sham-operated control group. Supplementation of these animals with either garlic oil or lovastatin or 17beta-estradiol, in addition to their hypocholesterolemic effect, could counterbalance all these changes. The results revealed that all three compounds significantly protected the hypogonadal bone loss as reflected by higher bone densities and higher bone mineral contents than the ovariectomized group of animals. The results emphasize that, like 17beta-estradiol, the hypocholesterolemic compounds garlic oil and lovastatin are also effective in suppressing bone loss owing to estrogen deficiency and their efficacy in the order of lower to higher is garlic < lovastatin < 17beta-estradiol.

Acid Phosphatase↗
PubMed2005

Atypical hearing loss in women with breast cancer receiving adjuvant treatment.

There are no reports of adjuvant treatments for early breast cancer causing hearing loss. Yet in this exploratory study 14/16 women who had received Fluorouracil, Epirubicin and Cyclophosphamide (FEC) chemotherapy regimen, 11 of whom also received endocrine treatment, had reduced hearing sensitivity, with 9/16 being atypical. It is not clear whether this finding is related to oestrogen reduction and/or ototoxicity but a more detailed investigation in this area is warranted given the large number of women with breast cancer who receive adjuvant treatments.

Adult↗
PubMed2005

Cortical organization of sensory corrections in visuomotor skill acquisition.

During sensorimotor skill acquisition, early learning of the required neuromuscular pattern and sensorimotor mappings is followed by an intermediate stage of gradually increasing consistency and efficiency of execution, which gives way, with persistent practice, to the later stages of automatization. It has been suggested that the intermediate stage is distinguished by refinements in the background sensory corrections that support, stabilize and smoothen the fine motor adjustments required by the new coordination. While the later stages of motor refinement are thought to be sub-cortically organized, the neurophysiology of the proposed sensory learning component in the intermediate stage is not well understood. During explicit learning of a visually cued finger-tap sequence, the present research used fMRI to isolate those cortical activations that were significant in the immediate post-learning phase, but were not also observed during the corresponding pre-learning phase. Such exclusively post-learning activation occurred significantly more in visual and somatosensory association areas, than in primary somatosensory or primary and secondary motor areas. These results show that the intermediate stage of skill acquisition has a significant sensory learning component, and that the process has observable cortical correlates.

Cerebral Cortex↗
PubMed2005

Reactive oxygen species from smooth muscle mitochondria initiate cold-induced constriction of cutaneous arteries.

Cold constricts cutaneous blood vessels by selectively increasing the activity of smooth muscle alpha2-adrenoceptors (alpha2-ARs). In mouse tail arteries, alpha2-AR constriction is mediated by alpha2A-ARs at 37 degrees C, whereas the cold-induced augmentation in alpha2-AR activity is mediated entirely by alpha2C-ARs. Cold causes translocation of alpha2C-ARs from the trans-Golgi to the plasma membrane, mediated by cold-induced activation of RhoA and Rho kinase. The present experiments analyzed the mechanisms underlying these responses. Mouse tail arteries were studied in a pressure myograph. Cooling the arteries (28 degrees C) caused a rapid increase in reactive oxygen species (ROS) in smooth muscle cells, determined by confocal microscopy of arteries loaded with the ROS-sensitive probes, dichlorodihydrofluorescein or reduced Mitotracker Red. The inhibitor of mitochondrial complex I rotenone (10 micromol/l), the antioxidant N-acetylcysteine (NAC; 20 mmol/l), or the cell-permeable mimic of superoxide dismutase MnTMPyP (50 micromol/l) did not affect vasoconstriction to alpha2-AR stimulation (UK-14304) at 37 degrees C but dramatically inhibited the response at 28 degrees C. Indeed, these ROS inhibitors abolished the cold-induced increase in alpha2-AR constrictor activity. NAC (20 mmol/l) or MnTMPyP (50 micromol/l) also abolished the cold-induced activation of RhoA in human cultured vascular smooth muscle cells and the cold-induced mobilization of alpha2C-ARs to the cell surface in human embryonic kidney 293 cells transfected with the receptor. The combined results suggest that cold-induced constriction is mediated by redox signaling in smooth muscle cells, initiated by mitochondrial generation of ROS, which stimulate RhoA/Rho kinase signaling and the subsequent mobilization of alpha2C-ARs to the cell surface. Altered activity of ROS may contribute to cold-induced vasospasm occurring in Raynaud's phenomenon.

Acetylcysteine↗
PubMed2005

Association of specific genotype and haplotype of p53 gene with cervical cancer in India.

BACKGROUND: The predictive value of codon 72 arginine homozygosity at the p53 gene for human papilloma virus associated cervical cancer risk remains inconclusive. It has also been proposed that the inheritance of specific germline haplotypes based on three biallelic polymorphisms of p53 (intron 3 16 bp duplication, codon 72 Bst UI (Arg/Pro), and intron 6 Nci I restriction fragment length polymorphism at nucleotide 13494) is a better predictor of various cancer risks. AIMS: To determine the genotype and haplotype frequency of these three p53 polymorphisms in 61 patients with cervical squamous cell carcinoma and 94 ethnically matched controls from the eastern region of India and estimate the risk, if any, of specific genotypes and haplotypes. METHODS: Samples were genotyped by polymerase chain reaction followed by variant specific restriction enzyme digestion. Haplotypes were estimated by the maximum likelihood method using the expectation maximisation algorithm. RESULTS: Genotype distributions of the three polymorphisms in patients and controls showed a good fit to the Hardy-Weinberg equilibrium. The p53 codon 72 arginine homozygous genotype was significantly over represented in patients compared with controls. Those with the homozygous arginine genotype exhibited a 2.59 fold higher risk of developing squamous cell carcinoma of the uterine cervix. A significant risk was also seen with a combination of two haplotypes, 1-2-1 and 1-2-2. CONCLUSION: p53 codon 72 arginine homozygotes appear to be at greater risk of developing squamous cell carcinoma of the uterine cervix. The high risk haplotypes 1-2-1 and 1-2-2 also contain the arginine allele, further strengthening this conclusion.

Adult↗
PubMed2005

Expression of somatostatin receptors in arginine vasopressin hormone-secreting olfactory neuroblastoma--report of two cases.

OBJECTIVE: Arginine vasopressin hormone-secreting olfactory neuroblastomas are extremely rare, with fewer than twenty cases reported in the literature. Two of these cases, both initially presenting with the syndrome of inappropriate antidiuretic hormone, are presented. The second tumour was successfully identified using somatostatin receptor (octreotide) radiographic scintography. METHOD: The pathological specimens from both cases were examined immunohistochemically for somatostatin receptors. RESULTS: Samples from both cases demonstrated positivity for somatostatin receptors. CONCLUSIONS: This report demonstrates the potential use of somatastatin analogues in the investigation, follow-up and treatment of patients with olfactory neuroblastoma.

Adult↗
PubMed2005

A pilot study for serological evidence of hantavirus infection in human population in south India.

BACKGROUND AND OBJECTIVES: Hantaviruses are rodent-borne viruses of the family Bunyaviridae that have been identified as aetiological agents of two human diseases, haemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). There are no reports of hantavirus infections in humans from India, hence this pilot study was undertaken to provide the serological evidence of hantavirus infections in humans in south India. METHODS: Serum samples were obtained from individuals with acute febrile illness and from voluntary blood donors, majority of whom were from south India. Serum samples were tested for anti-hantavirus IgM using a commercial enzyme immunoassay (EIA). Samples found positive by the EIA were tested by an indirect immunofluorescence assay (IFA) using slides coated with Seoul virus (SEOV) infected cells as substrate. RESULTS: Of the 152 serum samples from individuals with pyrexic illness, 23 (14.7%) were positive for anti-hantavirus IgM by EIA. In contrast, only 5.7 per cent of healthy blood donors were positive by this assay. Eighteen of the 22 (82%) EIA-positive samples from patients were positive by the IFA assay. In contrast, only 2 of the 5 (40%) blood donor EIA positive samples were positive in the IFA assay. INTERPRETATION AND CONCLUSION: The finding of this study indicated the possible presence of hantavirus infections in the human population of India presenting both as asymptomatic and symptomatic infections. Further studies need to be done to confirm the findings on a larger sample using molecular techniques.

Fluorescent Antibody Technique, Indirect↗
PubMed2004

[4-Bromo-2-[2-(5-bromo-2-oxidobenzylideneaminomethyl)phenyliminomethyl]phenolato-kappa4O,N,N',O']nickel(II).

In the title complex, [Ni(C(21)H(14)Br(2)N(2)O(2))], the Ni(II) atom is coordinated by the two imine N and two phenolate O atoms of the Schiff base ligand in a tetrahedrally distorted square-planar geometry. The Ni-N and Ni-O distances are within the ranges expected for Ni-Schiff base derivatives. Intermolecular C-H...O hydrogen bonds link the molecules into centrosymmetric dimers, forming R(2)(2)(12) (A) and R(2)(2)(10) (B) rings. These dimers combine to form a supramolecular ABAB... aggregate which propagates along the [100] direction.

Journal Article↗
PubMed2004

Molecular reorientations in liquid crystals pentyloxybenzylidine hexylanilene (PBHA) and butyloxybenzylidine octylanilene (BBOA).

Molecular reorientational motions in undeuterated pentyloxybenzylidine hexylanilene (PBHA or 5O.6) and butyloxybenzylidine octylanilene (BBOA or 4O.8) as studied by the quasielastic neutron scattering (QENS) technique in their different mesophases are reported. Models are built up in stages to account for the experimental elastic incoherent structure factor (EISF). It is found that there exist simultaneous reorientational motions of the chain group and the reorientational motions of the whole molecule around its molecular axis in the smectic- G, smectic- B, and smectic- C phases. In smectic- A and nematic phases, additional body axis fluctuations are found to exist in both 5O.6 and 4O.8 systems. The average amplitude of body axis fluctuations is found to be approximately 15 degrees and 25 degrees, respectively, in the smectic- A and nematic phases of 5O.6, and approximately 14 degrees and 29 degrees, respectively, in 4O.8.

Journal Article↗