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Biomedical subjects

A K Pandey

Publications and source records attributed to A K Pandey.

At least 19 recordsLinked to original sources
PubMed2006

Formation of silver nanoparticles in poly(perfluorosulfonic) acid membrane.

The formation of silver nanoparticles by chemical reduction of Ag+-loaded Nafion-117 membrane with NaBH4 was studied using radioactivity tagged ions. The counterion-exchange method (Ag(m)+ <--> Na(s)+) was used to obtain a membrane sample with a varying proportion of Ag+ ions. The X-ray elemental mapping across the thickness of the membrane by energy-dispersive X-ray spectrometer attached to the environmental scanning electron microscope (ESEM/EDAX) indicated that Na+ and Ag+ were uniformly distributed in the membrane samples before reduction. The average size of nanoparticles formed after reduction was found to be 15 +/- 3 nm, irrespective of the concentration of silver ions present in the membrane before reduction. Energy-dispersive X-ray fluorescence (EDXRF) analyses of the membrane samples, carried out before and after reduction, indicated that the Ag concentration on the membrane surface was considerably increased after reduction. EDXRF measurements of the membrane samples, obtained from reduction carried out in a dead end cell, indicated that Ag nanoparticles were formed only on the membrane surface exposed to NaBH4 solution. Reduction carried out with NaBH4 tagged with 22Na showed that the formation of Ag nanoparticles involved exchange of Ag+ ions from ion-exchange sites in the interior of the membrane with Na+ ions, followed by reduction of Ag+ ions with BH4- ions at the surface of membrane. The study of self-diffusion of water, Na+, and Cs+ ions in the membrane loaded with Ag nanoparticles indicated that formation of Ag nanoparticles did not affect the diffusional transport properties of the membrane. The ion-exchange capacity and water uptake capacity were also not affected by the formation of Ag nanoparticles in the membrane. The spatial distribution of Ag nanoparticles across the thickness of the membrane obtained by ESEM/EDAX showed that Ag nanoparticles were confined to a few-micrometer surface layer of the membrane. Based on these observations, an attempt has been made to explain the mechanism of the formation of Ag nanoparticles in the membrane.

Journal Article↗
PubMed2006

Genetic diversity studies of Kherigarh cattle based on microsatellite markers.

We report a genetic diversity study of Kherigarh cattle, a utility draught-purpose breed of India, currently declining at a startling rate, by use of microsatellite markers recommended by the Food and Agriculture Organization. Microsatellite genotypes were derived, and allelic and genotypic frequencies, heterozygosities and gene diversity were estimated. A total of 131 alleles were distinguished by the 21 microsatellite markers used. All the microsatellites were highly polymorphic, with mean (+/- s.e.) allelic number of 6.24 +/- 1.7, ranging 4-10 per locus. The observed heterozygosity in the population ranged between 0.261 and 0.809, with mean (+/- s.e.) of 0.574 +/- 0.131, indicating considerable genetic variation in this population. Genetic bottleneck hypotheses were also explored. Our data suggest that the Kherigarh breed has not experienced a genetic bottleneck in the recent past.

Alleles↗
PubMed2006

The auxin-inducible GH3 homologue Pp-GH3.16 is downregulated in Pinus pinaster root systems on ectomycorrhizal symbiosis establishment.

In an attempt to determine whether auxin-regulated plant genes play a role in ectomycorrhizal symbiosis establishment, we screened a Pinus pinaster root cDNA library for auxin-upregulated genes. This allowed the identification of a cDNA, Pp-GH3.16, which encodes a polypeptide sharing extensive homologies with GH3 proteins of different plants. Pp-GH3.16 was specifically upregulated by auxins and was not affected by cytokinin, gibberellin, abscisic acid or ethylene, or by heat shock, water stress or anoxia. Pp-GH3.16 mRNAs were quantified in pine roots inoculated with two ectomycorrhizal fungi, Hebeloma cylindrosporum and Rhizopogon roseolus. Surprisingly, Pp-GH3.16 was downregulated following inoculation with both fungal species. The downregulation was most rapid on establishment of symbiosis with an indole-3-acetic acid (IAA)-overproducing mutant of H. cylindrosporum, which overproduced mycorrhizas characterized by a hypertrophic Hartig net. This indicates that, despite being auxin-inducible, Pp-GH3.16 can be downregulated on establishment of symbiosis with a fungus that releases auxin. By contrast, Pp-GH3.16 was not downregulated in pine root systems inoculated with a nonmycorrhizal mutant of H. cylindrosporum, suggesting that the downregulation we observed in mycorrhizal root systems was a component of the molecular cross-talk between symbiotic partners at the origin of differentiation of symbiotic structures.

Agaricales↗
PubMed2006

Seasonal changes in plasma calcium and inorganic phosphate levels in relation to parathyroid structure of the grey quail, Coturnix coturnix coturnix Linnaeus.

Plasma Ca concentration (annual mean) in males Coturnix cotumix coturnix was 10.27 +/- 0.14 mg/100 ml while it was slightly higher (11.85 +/- 0.15 mg/100 ml) among females. Plasma Pi levels (annual mean) in males and females were 5.62 +/- 0.12 mg/100 ml and 6.52 +/- 0.20 mg/100 ml, respectively. While the males did not exhibit marked fluctuation in plasma Ca and Pi levels either in winter or summer, the females did record significant elevation in the levels of both these electrolytes during breeding season. The peak values of plasma Ca (17.66 +/- 0.38 mg/100 ml) and Pi (8.64 +/- 0.22 mg/100 ml) in females were observed during June. Parathyroid gland of the grey quail exhibited hyperactivity (hypertrophy and hyperplasia) during breeding season, however, the activity was more conspicuous among females than in males. The maximum increase in cell and nuclear diameters were observed in females during May-July. The follicles were also filled with AF- and PAS-positive materials during these months. The glands depicted signs of hypoactivity and degeneration during peak winter season (November-December) as evident by decrease in cell and nuclear diameters as well as vacuolation in the chief cells.

Animals↗
PubMed2005

Effect of reduction in tube current on reader confidence in paediatric computed tomography.

BACKGROUND: Computed tomography (CT) contributes significantly to the total radiation dose derived from medical imaging in children. As the number of CT examinations increases there is renewed interest in possible ways to minimize such radiation. AIM: To study the effect of decremental reduction in tube current settings on structural resolution and on reader confidence in being able to reach a final diagnosis. MATERIALS AND METHODS: The study involved spiral CT of children aged 0-13 years. CT performed at reduced mA settings (60-75, 76-90 and 91-130 mA for thoracic, abdominal and pelvic examinations, and 76-90 and 91-130 mA for cranial examinations) were compared with similar investigations at conventional settings (180-240 mA). Images were scored by two blinded readers for structural resolution and diagnostic confidence. Structural resolution was scored on a binary (adequate or not) scale for six structures each in cranial, thoracic and pelvic examinations and for eight structures in abdominal studies, and reader confidence was scored on a four-point scale as 25-100%. Scores from the two readers were averaged for comparison in subgroup analyses. RESULTS: Reduction of tube current settings to 75-90 mA for thoracic, abdominal and pelvic examinations and to 90-130 mA for cranial examinations was not associated with any significant deterioration in image quality. The number of scans considered satisfactory were comparable even at 60-75 mA, although the total relative scores for structural resolution at this setting were lower. CONCLUSION: Tube current settings can be significantly reduced in all paediatric age groups, in all regions. In younger children the impact of such reduction in tube current is likely to be greater. Cranial scans are more sensitive to such reductions as compared to thoracic or abdominopelvic examinations.

Adolescent↗
PubMed2005

Effects of diazinon on serum calcium and inorganic phosphate levels as well as ultrastructures of parathyroid and calcitonin cells of Rattus norvegicus.

Daily intramuscular administration of two doses--0.50 LD550 (150 mg/kg b w) and 0.75 LD50 (225 mg/kg b w) of diazinon for 14 days induced progressive hypocalcemia without altering serum inorganic phosphate value in Rattus norvegicus. Hypocalcemic response of the pesticide was dose- as well as time-dependent. Parathyroid chief cells of the experimental rats exhibited degranulation, vacuolation, loss of secretory granules and lipid droplets, decreased chromatin, and degenerative changes in endoplasmic reticulum, Golgi complex as well as cristae of the mitochondria. Not much of ultrastructural changes could be seen in the C cells of the rats treated with diazinon.

Animals↗
PubMed2004

Heterologous expression of a gene encoding a 35 kDa protein of Mycobacterium avium paratuberculosis in Escherichia coli.

The full-length open reading frame coding for a potentially immunogenic 35 kDa protein of Mycobacterium avium paratuberculosis was generated using polymerase chain reaction technology. The gene was inserted in-frame into Escherichia coli expression plasmid pQE32. The resulting recombinant plasmid pPMP35 was transformed into E. coli M15. Analysis of the E. coli induced with isopropyl-beta-D-thiogalactopyranoside revealed that the protein accumulated into the cytoplasm as insoluble inclusion bodies. The level of expression of the recombinant 35 kDa protein (P35) was more than 30% of the total protein of E. coli cells. Expression of the recombinant protein was confirmed by immunoblotting. The P35 reacted with a rabbit antiserum raised against a sonicate of M. a. paratuberculosis. The protein was also recognized by serum from a goat with clinical paratuberculosis. Further, a polyclonal antiserum against P35 recognized a 35 kDa band in a membrane fraction of M. a. paratuberculosis. Also, the protein provoked a significant skin reaction in outbred guinea pigs sensitized with M. a. paratuberculosis, as well as in those sensitized with Mycobacterium avium. The results indicate that the 35 kDa protein of M. a. paratuberculosis is a membrane protein, having a role in the cellular immune response.

Amino Acid Sequence↗
PubMed2004

Antifungal potential of Spilanthes calva after inoculation of Piriformospora indica.

We investigated the influence of Piriformospora indica on the antifungal principle of Spilanthes calva, a plant of high commercial value. An antifungal efficacy was shown by aqueous and petroleum ether extracts of S. calva against Fusarium oxysporum and Trichophyton mentagrophytes. The petroleum ether extract of S. calva was more effective than the aqueous extract in inoculated as well as uninoculated plants. The antifungal activity of the plant was enhanced due to the increase in spilanthol content after inoculation of P. indica.

Antifungal Agents↗
PubMed2004

Responses of serum calcium and inorganic phosphate levels, parathyroid gland and C cells of Rattus norvegicus to heptachlor administration.

Intramuscular administration of two doses: 0.50 LD50 (14.70 mg/kg b w) and 0.75 LD50 (22.30 mg/kg b w) of heptachlor in Rattus norvegicus for 14 days induced significant hypocalcemia without altering serum inorganic phosphate value. Parathyroid chief cells of the experimental rats exhibited degranulation, vacuolation, loss of secretory granules and lipid droplets, reduction in chromatin, and degenerative changes in endoplasmic reticulum and cristae of the mitochondria. Not much of histological and ultrastructural changes could be seen in C cells of the heptachlor treated rats.

Animals↗
PubMed2004

Inadvertent insertion of nasogastric tube into the brain.

An unusual case of a nasogastric (Ryle's) tube inserted in the brain in a patient having severe head injury with skull base fractures is reported here along with a brief review of literature. A 35 years male was referred from a peripheral institute following head trauma with endotracheal tube and nasogastric tube in situ. A CT scan of the brain showed multiple skull base fractures and a high parietal extradural hematoma. It also revealed that the nasogastric tube had inadvertently found its way into the brain through the lamina cribrosa of the ethmoid bone. The tube was removed under aseptic conditions in the operation theatre but the patient expired on day 2 of admission due to the head injuries sustained.

Adult↗
PubMed2003

Role of humic acid entrapped calcium alginate beads in removal of heavy metals.

Most of the available techniques for removal of heavy metals from solution such as leachates from waste sites are very expensive. The technique described in this paper is designed to study the removal of humic acid by alginate beads and the subsequent binding of the metals within the beads thus decreasing the leachability of heavy metals from a hazardous waste site. The entry of 500 mg/l humic acid into 3% calcium alginate beads in 24 h showed a distinct fluorescence as compared to the fluorescence shown by the entry of 100 and 250 mg/l of humic acid into alginate beads. Further, on treatment of calcium alginate beads containing 500 mg/l humic acid with metals such as Cu, Mn, Zn, Cr and Fe, quenching of fluorescence was noticed, which was maximum with Cu and minimum with Fe.

Alginates↗
PubMed2003

Removal of chromium and reduction of toxicity to Microtox system from tannery effluent by the use of calcium alginate beads containing humic acid.

Removal of chromium (Cr) from tannery effluents by recovery of metal also reduces the ecotoxicological impact. To develop such a process, columns packed with calcium alginate (CA) beads with or without humic acid (HA) have been used as an adsorbent and tannery effluent was passed through it. Concentration of Cr in beads and in different fractions collected after adsorption was measured. Change in total organic carbon content during the process was also noticed. The fractions were also tested for toxicity towards Microtox assay. EC(50) values were determined with the help of Microtox analyser 500. Data showed that the CA beads along with HA could be effectively utilised in removal of 54% Cr and also in reducing the toxicity (EC(50) (%) in 5 min=>100 in fractions collected after 72 h).

Adsorption↗
PubMed2003

Estimation of thyroid mass in Graves' disease by a scintigraphic method.

scintigraphic method for the estimation of the thyroid mass in patients with Graves' disease is described. The method was first standardized using thyroid phantoms with eight different volumes ranging from 5 to 110 cm(3). The planar and single photon emission computed tomography (SPECT) images of each phantom were acquired with four different activities [3.7 MBq (100 microCi), 11.1 MBq (300 microCi), 22.2 MBq (600 microCi) and 37 MBq (1.0 mCi) of 99mTc-pertechnetate] with a 20% window symmetrically placed over the photopeak of 99mTc. The thyroid lobes were enclosed with the help of regions of interest (ROI) tools and a threshold was selected to identify the thyroid boundaries. The same threshold was used in all slices of an image. In the phantom study, a 20% threshold for planar images and a 30% threshold for SPECT were found to be optimum for measuring the thyroid volume. The volume from planar images was calculated by the formula described by Allen and Goodwin (The scintillation counter as an instrument for in-vivo determination of thyroid weight. Radiology 1952; 58: 68-79), whereas, in SPECT images, the sum of the slice areas was multiplied by the slice thickness. The estimated volume of each phantom was compared and correlated with its actual volume. After standardization of the technique with phantom studies, planar scintigraphy (with 20% threshold) in 51 patients and SPECT (with 30% and 35% threshold) in 40 patients with Graves' disease were performed to estimate the thyroid size. The thyroid size was also estimated by ultrasonography, which showed good agreement with the scintigraphic method, particularly with SPECT.

Graves Disease↗
PubMed2003

Ultra-structural observations on the lymphoid organs of the freshwater catfish, Clarias batrachus (Linnaeus).

Light microscopic and ultra-structural studies of the lymphoid tissues such as blood immunocytes, spleen and pronephros of the freshwater catfish, Clarias batrachus, were carried out. The peripheral blood showed nucleated erythrocytes, total leucocytic count (TLC) more than that observed in mammalian blood and leucocytes with morphological appearance similar to the mammalian white blood cells (WBCs). The spleen and pronephros showed presence of numerous lymphocytes, monocytes and nucleated red blood cells (RBCs) along with hemosiderin-containing macrophages. The morphology of lymphoid organs of the catfish has been discussed in light of the evolution of the immune system in this class of vertebrates.

Animals↗
PubMed2002

Selective preconcentration and determination of chromium(VI) using a flat sheet polymer inclusion sorbent: potential application for Cr(VI) determination in real samples.

A method for sorption preconcentration of Cr(VI) from aqueous samples was developed using a polymer inclusion sorbent (PIS). The PIS used in this method was prepared by physical inclusion of Aliquat-336 in the matrix formed by cellulose triacetate and 2-nitrophenyl octyl ether. This sorbent was found to be stable, cost-effective, efficient for preconcentration of Cr(VI) present in the aqueous samples, and amenable to direct quantitative analysis of Cr(VI) held in it by neutron activation analysis and spectrophotometry. The quantifying of Cr(VI) in PIS by spectrophotometry was carried out by developing color directly on the PIS after reacting it with 1,5-diphenylcarbazide. The distinct color developed on the PIS even at very low concentrations of Cr(VI) suggests its possible use for field determination of Cr(VI). The composition of PIS was optimized to obtain maximum uptake of Cr(VI) without sacrificing uniformity in terms of thickness and distribution of ion-exchange sites, stability, and time required for quantitative sorption of Cr(VI) from aqueous samples. The Cr(VI) species held in the PIS, mainly HCrO4- and CrO4(2-), were found to vary as a function of pH of the aqueous samples from which Cr(VI) was preconcentrated. A close agreement was found in the abundances of Cr(VI) species held in the PIS with those reported in the literature for aqueous solutions at different pH. The variation of Cr(VI) species as a function of pH was found to have a significant impact on the tolerance to anions on the uptake of Cr(VI) in the PIS. The high selectivity of PIS toward Cr(VI) from aqueous solution at pH = 2 was explained on the basis of hydration of anions. The uptake of Cr(VI) was found to be fairly constant (88 +/- 3%) up to nearly complete exchange of counterions present in the PIS. The method developed in the present work was successfully used for the preconcentration of Cr(VI) from tap water and seawater samples containing low levels of Cr(VI).

Anion Exchange Resins↗
PubMed2001

Microbial metabolites as eco-friendly agrochemicals for the next millennium.

As a result of the increasing environmental and health-related problems caused by the synthetic agrochemicals currently used, suitable and non-hazardous innovative alternatives are being sought. Antagonism and allelopathy, both in nature and in agro-ecosystems, have attracted these researchers' attention, with the main goal of using these phenomena in the biological control of weeds. This article presents a review on the use and efficacy of microbial secondary metabolites which have potential as natural herbicides, either directly or as templates for bio-rational eco-friendly agrochemicals (allelochemicals). Their merits as alternatives to synthetic chemicals and biological control agents have been highlighted for an holistic approach in integrated pest/weed management.

Actinomycetales↗