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Biomedical subjects

S Puri

Publications and source records attributed to S Puri.

At least 19 recordsLinked to original sources
PubMed2006

Peripheral bone mineral density and its predictors in healthy school girls from two different socioeconomic groups in Delhi.

UNLABELLED: Peripheral bone density measurements are scarce and the factors, which predict bone mineral density at these sites, especially in children, are not clearly known. In this study, age, height, weight and alkaline phosphatase had a significant association on peripheral bone mineral density in healthy Indian school girls. INTRODUCTION: Factors that lead to the attainment of peak bone mass at peripheral sites, during period of growth are not clearly known. METHODS: Six-hundred and sixty-four randomly selected 7- to 17-year-old girls from upper and lower socioeconomic status (USES/LSES) schools were assessed clinically and a recording of their height and weight was undertaken. Serum calcium, phosphorus, total alkaline phosphatase (ALP), 25-hydroxyvitamin D (25-OHD) and parathyroid hormone (PTH) were measured in all of them. Bone mineral density (BMD) was measured at the distal forearm (BMDdf) and calcaneum (BMDca) by peripheral dual energy X-ray absorptiometry (pDXA). RESULTS: Girls belonging to the USES were significantly taller (149.7 +/- 12.3 cm vs 144.4 +/- 11.9 cm; P < 0.001) and weighed more (44.3 +/- 12.9 kg vs 35.9 +/- 10.0 kg; P < 0.001) than girls from the LSES. USES girls had a significantly higher mean serum calcium (9.3 +/- 0.7 mg/dl vs 9.2 +/- 0.8 mg/dl; P < 0.05) and significantly lower alkaline phosphatase (316 +/- 166 IU/l vs 423 +/- 228 IU/l; P < 0.01) and iPTH (29.9 +/- 18.4 pg/ml vs 45.7 +/- 64.6 pg/ml; P < 0.01). There was no significant difference in mean serum phosphorus and 25-OHD levels between the two groups. USES subjects had higher BMD at both sites than LSES subjects. BMDdf and BMDca increased with age and tended to plateau by 16 years and 12 years of age respectively in both the groups. Age, height and weight explained approximately 50% of the variability, while biochemical parameters explained approximately 30% of variability in BMD at both the sites. The only biochemical parameter which had a significant association with BMD was ALP at the distal forearm. CONCLUSION: In conclusion, age, nutrition, height and weight are significantly associated with BMD at peripheral sites.

Adolescent↗
PubMed2006

Preparative high-performance liquid chromatographic separation of naphthodianthrones from St. John's Wort.

St. John's Wort (Hypericum perforatum), a perennial flowering plant, has been used medicinally for thousands of years and has most recently been identified as an effective treatment for mild to moderate depression and neuralgic disorders. This work presents a procedure for the isolation of naphthodianthrones from St. John's Wort by an accelerated extraction and separation of marker compounds by preparative high-performance liquid chromatography (HPLC) with photodiode array detection. The accelerated extraction method minimizes the extraction time and increases the yield, and the marker compounds obtained by preparative HPLC are of 98% purity. The compounds are characterized by liquid chromatography-mass spectrometry (electrospray ionization) and NMR spectra.

Anthracenes↗
PubMed2006

Effects of oestrogen on trigeminal ganglia in culture: implications for hormonal effects on migraine.

Although migraine is more common in women than men and often linked to the menstrual cycle, few studies have investigated the biological basis of hormonal influences on the trigeminovascular system. In the present study we investigated the effect of physiological levels (10(-9) m) oestrogen on female rat trigeminal ganglia in vitro. Immunocytochemical analysis demonstrated the presence of oestrogen receptor-alpha in a predominantly cytoplasmic location and in neurites. Microarray analysis demonstrated that oestrogen treatment regulates several genes with potential relevance to menstrual migraine. The genes that were upregulated included synapsin-2, endothelin receptor type B, activity and neurotransmitter-induced early gene 7 (ania-7), phosphoserine aminotransferase, MHC-1b, and ERK-1. Down-regulated genes included IL-R1, bradykinin B2 receptor, N-tropomodulin, CCL20, GABA transporter protein, fetal intestinal lactase-phlorizin hydrolase, carcinoembryonic antigen-related protein, zinc finger protein 36, epsin 1 and cysteine string protein. Protein activity assays demonstrated that exposure of the cultured neurons to oestrogen leads to activation of ERK, which has been linked to inflammatory pain. Immunocytochemistry demonstrated that activated ERK was present in neurons containing peripherin, a marker of nociceptive neurons. Several of the genes in the present study may provide potential targets for understanding the association of oestrogen with migraine and other hormone-related orofacial pain.

Animals↗
PubMed2005

Comparison of growth, biomass and nutrient distribution in five promising clones of Populus deltoides under an agrisilviculture system.

Variations in growth, above- and below-ground biomass and nutrient distribution were examined in five clones (G3, G48, 65/27, D121 and S7C1) of Populus deltoides grown under agrisilviculture system in sub-humid tropics of Central India. The monoclonal blocks were planted at 4x5 m in a randomized block design with three replications. Diameter at breast height (dbh) and tree height were consistently higher in clone 65/27 and lowest in clone S7C1. Mean annual increments (MAI) in dbh and height were 1.6 and 1.3 times higher in clone 65/27 compared to clone S7C1. Total biomass varied from 48.5 to 62.2 Mg ha(-1) in six-year-old clones. In rank order, the total biomass of clones was: 65/27>D121>G48>G3>S7C1. Stem wood accounted 60.4-68.9% to total biomass followed by coarse roots (12.2-18.9%), branches (12.3-15%), leaves (3.02-6.9%) and fine roots (1.5-2.7%). Root-shoot ratio ranged from 0.2 to 0.35. It was highest in clone G48 and lowest in clone S7C1. In six-year-old clones, total N ranged from 184.3 to 266.3 kg ha(-1), P from 16.8 to 31.1 kg ha(-1) and K from 81.9 to 128.7 kg ha(-1). Total N and P were highest in clone 65/27, while K in clone G48. Nutrients were lowest in clone S7C1. In general, maximum nutrients (N, P and K) were allocated to above-ground components (leaves>stem>branches) than below-ground components. Available N, P and K in the soil improved significantly after six years of planting. It was higher in 0-20 cm and decreased with soil depth. At 0-20 cm soil depth, N increased from 14.9% to 24.1%, P from 17.2% to 23.3% and K from 3.1% to 5.1% under different clones. The yield of both soybean and wheat reduced under poplar clones. Yield losses in soybean ranged from 10.1% to 33% and wheat from 15% to 30.3% under different clones. The management strategies for reducing tree-crop competition and nutrient export from the site under P. deltoides based agrisilviculture system for achieving sustainable production are discussed.

Agriculture↗
PubMed2003

Growth, biomass, carbon storage and nutrient distribution in Gmelina arborea Roxb. stands on red lateritic soils in central India.

Growth, biomass, carbon storage and nutrient (N, P and K) variations in 1 to 6-year-old chronosequence plantations of Gmelina arborea were studied in three degraded red lateritic sites in central India. Growth parameters (dbh, total height and number of branches) varied significantly due to difference in age and site quality, but tree density showed non-significant variation. Stand biomass ranged from 3.94 (1-year-old) to 53.67 Mgha(-1) (6-year-old) and stand carbon in 6-year-old plantations ranged from 24.12 to 31.12 Mgha(-1) at different sites. Among the tree components, the stem wood accounted for maximum C (56.25% at site 1) followed by branches (19.8% at site 3), roots (18.51% at site 2) and foliage (7.01% at site 3). Mean annual C accretion at 6 years age of plantation was highest in site 3 and it was 0.35, 2.66, 0.965 and 0.87 Mgha(-1) for leaf, stem, branches and roots, respectively. Quantity of nutrients increased with age. Total nitrogen accumulation in 6-year-old stands at the three sites ranged from 212.9 to 279.5 kgha(-1) with a mean annual storage of 238.43 kgha(-1) and total K ranged from 170.8 to 220.5 kgha(-1) with a mean annual storage of 189.93 kgha(-1). Phosphorous accumulation was lowest with a mean storage of 16.75 kgha(-1). The organic carbon and nutrients in the soils improved significantly after 6 years of G. arborea planting. Soil organic carbon increased from 8.46 to 14.02 Mgha(-1) within 6 years. At soil depths 0-20 cm, 21-40 cm and 41-60 cm, available N enhanced by 14.85%, 11.98% and 11.25%, K by 10%, 9.13% and 10.63%, whereas phosphorous declined by 26%, 23% and 20%, respectively. At 6 years, G. arborea stands sequestered 31.37 Mgha(-1) carbon. The nutrient management strategies in relation to carbon accretion in G. arborea stands on degraded lateritic sites are discussed.

Biomass↗
PubMed2001

Kinetics of phase separation in ternary mixtures.

We present detailed results from Monte Carlo simulations of the kinetics of phase separation in ternary mixtures. We focus on the case of ABV mixtures (where V denotes a vacancy) and investigate segregation kinetics resulting from V-mediated dynamics. We provide heuristic arguments for the existence of different morphologies in various parameter regimes. Furthermore, we present comprehensive numerical results for various characteristic features of the domain growth process, e.g., real-space correlation functions, domain-size distribution functions, and growth laws.

Journal Article↗
PubMed2001

Nonequilibrium dynamics in the complex Ginzburg-Landau equation.

Results from a comprehensive analytical and numerical study of nonequilibrium dynamics in the two-dimensional complex Ginzburg-Landau equation have been presented. In particular, spiral defects have been used to characterize the domain growth law and the evolution morphology. An asymptotic analysis of the single-spiral correlation function shows a sequence of singularities-analogous to those seen for time-dependent Ginzburg-Landau models with O(n) symmetry, where n is even.

Journal Article↗
PubMed2001

Nonequilibrium dynamics of the complex Ginzburg-Landau equation: analytical results.

We present a detailed analytical and numerical study of nonequilibrium dynamics for the complex Ginzburg-Landau equation. In particular, we characterize evolution morphologies using spiral defects. This paper is the first in a two-stage exposition. Here, we present analytical results for the correlation function arising from a single-spiral morphology. We also critically examine the utility of the Gaussian auxiliary field ansatz in characterizing a multispiral morphology. In the next paper of this exposition we will present detailed numerical results.

Journal Article↗
PubMed2001

Kinetics of phase separation in polymer-solvent mixtures.

We investigate the kinetics of phase separation in systems with a strong asymmetry in the mobility. This simple model system mimics the segregation kinetics of polymer-solvent mixtures, where the polymer-rich phase forms a low-mobility gel. We obtain detailed numerical results for this model, both without and with thermal noise. In the absence of thermal noise, we find that domain growth is slowed down drastically when the low-mobility phase percolates the system. However, thermal noise restores rapid domain growth through a Brownian coalescence mechanism.

Journal Article↗
PubMed2001

Determination of vaporization enthalpies of polychlorinated biphenyls by correlation gas chromatography.

The vaporization enthalpies of 16 polychlorinated biphenyls have been determined by correlation gas chromatography. This study was prompted by the realization that the vaporization enthalpy of the standard compounds used in previous studies, octadecane and eicosane, were values measured at 340 and 362 K, respectively, rather than at 298 K. Adjustment to 298 K amounts to a 7-8 kJ/mol increment in the values. With the inclusion of this adjustment, vaporization enthalpies evaluated by correlation gas chromatography are in good agreement with the values determined previously in the literature. The present results are based on the vaporization enthalpies of several standards whose values are well established in the literature. The standards include a variety of n-alkanes and various chlorinated hydrocarbons. The vaporization enthalpies of PCBs increased with the number of chlorine atoms and were found to be larger for meta- and para-substituted polychlorinated biphenyls.

Journal Article↗
PubMed2001

Surface-directed spinodal decomposition in binary fluid mixtures.

We consider the phase separation of binary fluids in contact with a surface, which is preferentially wetted by one of the components of the mixture. We review the results available for this problem and present numerical results obtained using a mesoscopic level simulation technique for the three-dimensional problem.

Journal Article↗
PubMed2001

Kinetics of domain growth in systems with local barriers.

We study domain growth in spin-1 lattice models having nonconserved spin-flip kinetics with local barriers. Our primary motivation is to model the relaxational behavior of physical systems in which molecular motion is impeded by local kinetic barriers. The kinetic constraint is such that a spin from an up (down) state can flip to a down (up) state only via the zero state, which has a higher energy. We examine how the usual curvature-driven domain growth is affected by these local barriers, and whether the single-spin barriers have a collective effect. This paper presents comprehensive numerical results for phase ordering dynamics in this model using Monte Carlo simulations. We demonstrate dynamical scaling for domain-size distribution functions and spatial correlation functions. We also present results for the time dependence of characteristic length scales and autocorrelation functions. The length-scale behavior is interpreted in terms of the random walk of steps on domain boundaries. Furthermore, we present a simple stochastic model to derive an analytic expression for the autocorrelation function, which exhibits a stretched-exponential behavior over an extended regime-in agreement with our numerical simulations.

Journal Article↗
PubMed2001

Power laws and crossovers in off-critical surface-directed spinodal decomposition.

We study the dynamics of phase separation in binary mixtures near a surface with a preferential attraction for one of the components of the mixture. We obtain detailed numerical results for a range of mixture compositions. In the case where the minority component is attracted to the surface, wetting layer growth is characterized by a crossover from a surface-potential-dependent growth law to a universal law. We formulate a simple phenomenological model to explain our numerical results.

Journal Article↗
PubMed2001

Hysteresis effects in spin systems with quenched disorder.

We present detailed numerical results for hysteresis effects in spin-glass systems. In particular, we focus on the dependence of hysteresis loop area on (a) disorder amplitude and (b) frequency of the applied magnetic field.

Journal Article↗