PubMed Health⌕ Search

Biomedical subjects

A Dhar

Publications and source records attributed to A Dhar.

At least 19 recordsLinked to original sources
PubMed2006

Neuroprotective effects of FeTMPyP: a peroxynitrite decomposition catalyst in global cerebral ischemia model in gerbils.

Peroxynitrite involvement has been implicated in the neuronal damage. In the present study, we have investigated the neuroprotective effects of peroxynitrite decomposition catalyst (FeTMPyP) on global cerebral ischemia. Global cerebral ischemia-reperfusion (IR) injury was produced by 5 min occlusion of both common carotid arteries followed by reperfusion of 96 h in the adult male Mongolian gerbils. The extent of injury was assessed behaviorally by measuring neurological functions, locomotor activity, passive avoidance test and by histopathological evaluation of extent of damage to CA1 hippocampal pyramidal region. FeTMPyP (1 and 3 mgkg(-1), i.p., administered 30 min prior to ischemia) treatment improved the neurological functions, reduced the hyperlocomotion and memory impairment in IR challenged gerbils. The loss of neurons from the pyramidal layer of the CA1 region caused by global IR injury was attenuated with FeTMPyP. FeTMPyP also inhibited lipid peroxidation as evident from reduction in brain malondialdehyde levels. These results suggest that peroxynitrite decomposition catalyst may be effective neuroprotective agent for global cerebral ischemia.

Animals↗
PubMed2005

Spin glasses in the limit of an infinite number of spin components.

We consider spin glass models in which the number of spin components m is infinite. In the formulation of the problem appropriate for numerical calculations proposed by several authors, we show that the order parameter defined by the long-distance limit of the correlation functions is actually zero and there is only "quasi-long-range order" below the transition temperature. Nonetheless, there can be a finite temperature phase transition where the decay of correlations changes from exponential to power law. We also show that the spin glass transition temperature is zero in three dimensions so power-law behavior only occurs at T=0 in this case. We also argue that the order of limits, m-->infinity and N-->infinity is important, where N is the number of spins.

Journal Article↗
PubMed2004

Diverticular disease of the colon: ethnic differences in frequency.

BACKGROUND: Colonic diverticular disease is more common in Western populations than in developing countries. AIM: To determine whether the frequency of colonic diverticular disease is different in British patients of Indian-subcontinent Asian origin compared with other ethnic groups. METHODS: All colonoscopies performed over a 3-year period in a London hospital were studied. Patients of Indian-subcontinent Asian origin were identified by name. RESULTS: Five of 134 Indian-subcontinent Asian males (4%) had colonic diverticular disease, compared with 278 of 1268 patients of other ethnic groups (22%; P < 0.001). Five of 91 Indian-subcontinent Asian females (6%) had colonic diverticular disease, compared with 333 of 1486 patients of other ethnic groups (23%; P < 0.001). Although patients of Indian-subcontinent Asian origin (54.8 +/- 15.8 years) were younger than those of other ethnic groups (60.3 +/- 17.8 years; P < 0.0001), the ethnic difference in the frequency of diverticular disease persisted even when age was taken into account. CONCLUSION: There is a lower frequency of colonic diverticular disease in Indian-subcontinent Asians presenting for colonoscopy, compared with other ethnic groups. This cannot be explained by sex or age differences. Our findings require confirmation, but may provide opportunities for research into the aetiology of colonic diverticular disease.

Adult↗
PubMed2004

Endometrioid carcinoma of uterus and ovary.

A thirty-two-year-old married woman presented with pain abdomen and polymenorrhoea. Her uterus was bulky and one of the fornices was full. USG of abdomen revealed unilateral ovarian tumour associated with a mass in the uterus. Histopathological report revealed synchronous endometrioid carcinoma of the uterus and the ovary with morphological evidences in favour of independent primary carcinomas. With these perspectives the present case is reported where endometrioid carcinomas of uterus and ovary are two separate primary tumours.

Adult↗
PubMed2002

Purification and characterization of a Galactomyces reessii hydratase that converts 3-methylcrotonic acid to 3-hydroxy-3-methylbutyric acid.

Cell free extracts of Galactomyces reessii contain a hydratase as the key enzyme for the transformation of 3-methylcrotonic acid to 3-hydroxy-3-methylbutyric acid. Highest levels of hydratase activity were obtained during growth on isovaleric acid. The enzyme, an enoyl CoA hydratase, was purified 147-fold by precipitation with ammonium sulphate and successive chromatography over columns of DE-52, Blue Sepharose CL-6B and Sephacryl S-200. During purification, hydratase activity was measured spectrophotometrically (OD change at 263 nm) for 3-methylcrotonyl CoA and crotonyl CoA as substrates. The enzyme displayed highest activity with crotonyl CoA with a Kcat of 1,050,000 min(-1). The ratio of crotonyl CoA to 3-methylcrotonyl CoA activities was constant (20:1) during all steps of purification. The Kcat for crotonyl CoA was also about 20 times greater than the Kcat for 3-methylcrotonyl CoA (51,700 min(-1). The enzyme had pH and temperature optima at 7.0 and 35 degrees C, a native Mr of 260 +/- 4.5 kDa and a subunit Mr of 65 kDa, suggesting that the enzyme was a homotetramer. The pI of the purified hydratase was 5.5, and the N-terminal amino acid sequence was VPEGYAEDLLKGKMMRFFDS. Hydratase activity for 3-methylcrotonyl CoA was competitively inhibited by acetyl CoA, propionyl CoA and acetoacetyl CoA.

Amino Acid Sequence↗
PubMed2001

Topological phases near a triple degeneracy.

We study the pattern of three-state topological phases that appears in systems with real Hamiltonians and wave functions. We give a simple geometric construction for representing these phases. We then apply our results to understand previous work on three-state phases. We show that the "mirror symmetry" of wave functions noticed in microwave experiments can be simply understood in our framework.

Journal Article↗
PubMed2001

Heat conduction in the disordered harmonic chain revisited.

A general formulation is developed to study heat conduction in disordered harmonic chains with arbitrary heat baths, satisfying the fluctuation-dissipation theorem. A simple formal expression for the heat current J is obtained, from which its asymptotic system-size (N) dependence is extracted. It is shown that "thermal conductivity" depends not just on the system itself but also on the spectral properties of the heat baths. As special cases we recover earlier results that gave J approximately 1/N(3/2) for fixed boundaries and J approximately 1/N(1/2) for free boundaries. Other choices give other power laws including the "Fourier behavior" J approximately 1/N.

Journal Article↗
PubMed2001

Heat conduction in a one-dimensional gas of elastically colliding particles of unequal masses.

We study the nonequilibrium state of heat conduction in a one-dimensional system of hard point particles of unequal masses interacting through elastic collisions. A BBGKY-type formulation is presented and some exact results are obtained from it. Extensive numerical simulations for the two-mass problem indicate that, even for arbitrarily small mass differences, a nontrivial steady state is obtained. This state exhibits local thermal equilibrium and has a temperature profile as predicted by kinetic theory. The temperature jumps typically seen in such studies are shown to be finite-size effects. The thermal conductivity appears to have a very slow divergence with system size, different from that seen in most other systems.

Journal Article↗
PubMed2001

MHC class I chain-like gene A (MICA) and its associations with inflammatory bowel disease and peripheral arthropathy.

MHC class I chain gene A (MICA) is a non-classical Class I gene which is expressed on the surface of epithelia without beta 2-microglobulin. The gene is found in the major histocompatibility complex (MHC) in tight linkage disequilibrium with human leucocyte antigen-B (HLA-B). Its precise function is unknown, but it interacts with gamma delta T cells of the intestinal immune system. This region of the MHC has been implicated in inflammatory bowel disease (IBD) pathogenesis by recent association mapping studies and this study was performed to examine the prevalence of MICA gene polymorphisms in IBD, in particular in type 2 peripheral arthropathy (PeA), which also has a strong HLA-B association. An assessment of the prevalence of MICA polymorphisms in IBD was made. Blood from 50 ulcerative colitis (UC) and 50 Crohn's disease controls was taken and MICA status determined using allele-specific PCR for 16 known alleles of MICA. A further 91 UC patients were recruited to confirm the results of this stage, and then the polymorphisms were studied in 52 type 1 and 45 type 2 PeA patients. The MICA status of these groups was compared with 118 blood and organ donor controls with appropriate correction for multiple comparisons. UC overall was associated with possession of MICA*007 in 32% compared to 11% of controls (P(c) = 0.017). This association was confirmed in a second cohort of 91 patients (23% versus 11%, P = 0.02). These were independent of HLA class I status. Type 2 IBD PeA was associated with MICA*008 in 98% compared to 73% of controls (P = 0.0001). MICA*007 is associated with susceptibility to UC in our population and MICA*008 with type 2 IBD PeA. Further work is now required to assess the distribution and expression of MICA throughout the gut in health and disease.

Case-Control Studies↗
PubMed2001

Maternal mortality in rural India: a hospital based, 10 year retrospective analysis.

OBJECTIVES: To estimate the maternal mortality ratio (MMR) in Ludhiana, a city of Northern India in order to determine the causes associated with MMR and to suggest ways to reduce it. METHODS: Retrospective analysis of the mortality records of obstetrics cases in Christian Medical College, Ludhiana, India. RESULTS: The mean MMR for the 10 year period was 785 per 100,000 live births. Of the total 116 reported maternal deaths, 44 (41.9%) were due to induced septic abortion. The reasons were unwanted pregnancy in 22 (50%) and 11 (25%) were female feticide. CONCLUSIONS: In our hospital based analysis, MMR was very high. Most maternal deaths are preventable by intervention at the appropriate time and it is important for health professionals, policy makers and politicians to implement the introduction of programs for reducing maternal mortality. Special emphasis should be placed on antenatal care, the establishment of a registration system and measures to abolish illegal abortion.

Abortion, Induced↗
PubMed2001

Effect of immunization against the alpha N (alphaN) and alpha C (alphaC) peptides of the alpha43 subunit of inhibin on antral follicular growth and atresia and the patterns of gonadotrophin secretion in ewes.

The aims of this study were to investigate the role of inhibin in the distribution of healthy and atretic antral follicles and the secretion patterns of gonadotrophins. Ewes were actively immunized against either alphaN or alphaC of the inhibin alpha subunit with a primary injection and three booster injections. The control ewes received adjuvant only. The ovaries were removed either before or at 24 h after hCG administration in a synchronized follicular phase 48 h after removal of intravaginal progesterone pessaries. Morphological observations were made on every fifth section of the complete ovary (one per ewe) stained with haematoxylin and eosin. The mean number of corpora lutea observed per ewe with corpora lutea was not significantly different in ewes immunized against alphaN (2.4; alphaN-immunized ewes) or alphaC (2.6; alphaC-immunized ewes), and control (2.4) ewes, although some corpora lutea appeared cystic in the immunized ovaries. Compared with luteal phase concentrations, mean basal FSH concentrations in the early follicular phase were significantly increased in the alphaC-immunized ewes, similar in alphaN-immunized ewes and reduced in control ewes. No differences were observed in any of the LH parameters. Before hCG treatment, healthy antral follicles > 1 mm in diameter were not observed in any of the 52 follicles in the aC-immunized ewes and were observed in one of 37 follicles from alphaN-immunized ewes compared with 19 of 28 follicles in control ewes (P < 0.0001). For healthy antral follicles < 1 mm in diameter, there were 72 of 85 follicles in the alphaC-immunized ewes, 79 of 81 follicles in the alphaN-immunized ewes and 81 of 82 follicles in the control ewes. Similar results were obtained in healthy antral follicles < 1 mm in diameter at 24 h after hCG administration. In contrast to the control ewes, no healthy preovulatory follicles (> 6 mm in diameter) were observed in alphaN- and alphaC-immunized ewes either before or 24 h after hCG administration. Two newly formed corpora lutea from alphaC-immunized ovaries contained retained oocytes compared with none in control and alphaN-immunized ovaries. In conclusion, immunization against alphaN and alphaC may result in disruption of the normal processes of antral follicular growth and maturation independent of the concentrations of FSH and LH.

Animals↗
PubMed2001

Transcatheter therapy of intravisceral bleeding.

Intravisceral bleeding is a life-threatening situation demanding fast and active steps to control, unless it stops spontaneously as in a few lucky patients. A surgical approach is a major intervention with its associated procedural risks when the site is in organs other than the spleen. The transcatheter approach helps in precise location and embolization of the bleeding site; it is a more practical approach that has been known for the past 2 decades to be effective and provide good long-term results. However, the transcatheter approach has been reported in fewer than 200 cases in the literature. Our small series of 43 cases shows initial success of 95% and a fatal early recurrence of only 2.4%. Non-hemorrhagic etiology (sepsis, head injury, etc.) was the major cause of early death (14.6%) among the successfully embolized cases. Long-term follow-up shows recurrence (4.8%) only in the group of chronic etiology. Transcatheter embolization of intravisceral bleeding with Gel-Foam and/or poly-vinyl alcohol particles is a swift, effective and precise method of treatment without major operational hazards.

Embolization, Therapeutic↗
PubMed2001

Purification and characterization of an invertase produced by Aspergillus ochraceus TS.

Purification and characterization of an extracellular invertase produced by Aspergillus ochraceus TS are reported. The enzyme was purified (42-fold) from culture filtrate by salt precipitation, ion-exchange and gel filtration. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) of the purified enzyme showed a single band of molecular mass 66 kDa. The molecular mass of the native enzyme was found to be 130 kDa by gel filtration. The purity of the protein was also checked against its antiserum raised in rabbits by two-dimensional immunodiffusion in agarose gel and Western blot that showed a single band. It is a glycoprotein with mannose as its carbohydrate residue. The enzyme showed high affinity for sucrose with a Km of 3.5 mM. The amino acid analysis revealed a high proportion of acidic residues but it had a low content of cysteine, histidine and arginine comparable to other fungal invertases.

Amino Acids↗