Biomedical subjects

D P Singh

Publications and source records attributed to D P Singh.

At least 19 recordsLinked to original sources

PubMed2006

High-performance liquid chromatographic method for the quantification of phenolics in 'Chyavanprash' a potent Ayurvedic drug.

Quantification of bioactive principles through modern analytical tools is essential for establishing the authenticity, credibility, prescription and usage of Ayurvedic medicines/herbal formulations. 'Chyavanprash' is one of the oldest and most popular Ayurvedic preparations, used widely as a health promotive and disease preventive 'Rasayana' drug in India and elsewhere. The rejuvenating and tonic properties of 'Chavanprash' are considered mainly due to their antioxidant principles, which in turn is due to the presence of phenolic compounds. A simple high-performance liquid chromatography (HPLC) method for the separation and quantitative determination of the major antioxidant compounds from 'Chyavanprash' has been developed. The use of Waters Symmetry column and an acidic mobile phase enabled the efficient separation of phenolic compounds (catechin, quercetin-3-O-rutinoside, syringic acid and gallic acid) within a 35 min analysis. Validation of the method was done with a view to demonstrate its selectivity, linearity, precision, accuracy and robustness. In addition optimization of the complete extraction of phenolic compounds were also studied.

Antioxidants↗

PubMed2006

Differential methods of inoculation of plant growth-promoting rhizobacteria induce synthesis of phenylalanine ammonia-lyase and phenolic compounds differentially in chickpea.

Foliar spray and micro-injection of plant growth-promoting rhizobacterial species, viz. Pseudomonas fluorescens and P. aeruginosa on chickpea induced synthesis of phenylalanine ammonia-lyase (PAL) when tested against Sclerotinia sclerotiorum. Induction of PAL was also associated with increased synthesis of phenolic compounds such as tannic, gallic, caffeic, chlorogenic and cinnamic acids. Treatment with P. fluorescens was found to be more effective in inducing phenolic compounds as compared to P. aeruginosa. However, persistence of PAL activity was observed more with P. aeruginosa. Although both the inoculation methods were effective, foliar application was found to be superior to micro-injection in terms of rapid PAL activity leading to the synthesis of phenolic compounds.

Antibiosis↗

PubMed2006

Antibacterial Co(II), Ni(II), Cu(II) and Zn(II) complexes of Schiff bases derived from fluorobenzaldehyde and triazoles.

Antibacterial Schiff bases derived from 1,2,4-triazoles as well as their metal complexes incorporating cobalt(II), nickel(II), copper(II) and zinc(II) have been synthesized and characterized. Physico-chemical studies suggest that an octahedral geometry for the cobalt(II), nickel(II) and zinc(II)and square-planer geometry for the copper(II) complexes. These complexes have been screened for antibacterial activity against three Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis and Bacillus subtilis) and two Gram-negative (Salmonella typhi and Pseudomonas aeruginosa) bacterial strains, and results compared with the activity of the free ligands. The metal complexes were found to be more potent against one or more bacterial strains than the free ligands.

Anti-Bacterial Agents↗

PubMed2005

Gene expression profiling of diabetic and galactosaemic cataractous rat lens by microarray analysis.

AIMS/HYPOTHESIS: Osmotic and oxidative stress is associated with the progression and advancement of diabetic cataract. In the present study, we used a cDNA microarray method to analyse gene expression patterns in streptozotocin-induced diabetic rats and galactose-fed cataractous lenses. In addition, we investigated the regulation and interaction(s) of anti-oxidant protein 2 and lens epithelium-derived growth factor in these models. METHODS: To identify differential gene expression patterns, one group of Sprague-Dawley rats was made diabetic with streptozotocin and a second group was made galactosaemic. Total RNA was extracted from the lenses of both groups and their controls. Labelled cDNA was hybridised to Atlas Rat Arrays. Changes in gene expression level were analysed. Real-time PCR and western analysis were used to validate the microarray results. RESULTS: The expression of 31 genes was significantly modulated in hyperglycaemic lenses compared with galactosaemic lenses. Notably, transcript and protein levels of B-cell leukaemia/lymphoma protein 2 and nuclear factor-kappaB were significantly elevated in rat lenses at 4 weeks after injection of streptozotocin. At a later stage, mRNA and protein levels of TGF-beta were elevated. However, levels of mRNA for IGF-1, lens epithelium-derived growth factor and anti-oxidant protein 2 were diminished in streptozotocin-induced diabetic cataract. CONCLUSIONS/INTERPRETATIONS: These results provide evidence that progression of sugar cataract involves oxidative- and TGF-beta-mediated signalling. These pathways may promote abnormal gene expression in the hyperglycaemic and galactosaemic states and thus may contribute to the symptoms associated with these conditions. Since oxidative stress seems to be a major event in cataract formation, supply of anti-oxidant may postpone the progression of such disorders.

Animals↗

PubMed2005

Impaired homeostasis and phenotypic abnormalities in Prdx6-/-mice lens epithelial cells by reactive oxygen species: increased expression and activation of TGFbeta.

PRDX6, a member of the peroxiredoxins (PRDXs) family, is a key player in the removal of reactive oxygen species (ROS). Using targeted inactivation of the Prdx6 gene, we present evidence that the corresponding protein offsets the deleterious effects of ROS on lens epithelial cells (LECs) and regulates gene expression by limiting its levels. PRDX6-depleted LECs displayed phenotypic alterations and elevated alpha-smooth muscle actin and betaig-h3 expression (markers for cataractogenesis), indistinguishable from transforming growth factor beta (TGFbeta)-induced changes. Biochemical assays disclosed enhanced levels of ROS, as well as high expression and activation of TGFbeta1 in Prdx6-/- LECs. A CAT assay revealed transcriptional repression of lens epithelium-derived growth factor (LEDGF), HSP27, and alphaB-crystallin promoter activities in these cells. A gel mobility shift assay demonstrated the attenuation of LEDGF binding to heat shock or stress response elements present in these genes. A supply of PRDX6 toPrdx6-/- LECs reversed these changes. Based on the above data, we propose a rheostat role for PRDX6 in regulating gene expression by controlling the ROS level to maintain cellular homeostasis.

Animals↗

PubMed2005

Immunomodulatory effects of curcumin.

Curcumin (diferuloylmethane), found in the spice turmeric, exhibits anti-inflammatory, antioxidant, and chemopreventive activities. However, the effect of curcumin on the immunological responses largely remains unknown. In this study we have investigated the effect of curcumin on mitogen (phytohaemagglutinin; PHA) stimulated T-cell proliferation, natural killer (NK) cell cytotoxicity, production of cytokines by human peripheral blood mononuclear cells (PBMCs), nitric oxide (NO) production in mouse macrophage cells, RAW-264.7. Furthermore, we have carried out an electromobility shift assay to elucidate the mechanism of action of curcumin at DNA protein interaction level. We observed that curcumin inhibits PHA-induced T-cell proliferation, interleukin-2 production, NO generation, and lipopolysachharide-induced nuclear factor-kappaB (NF-kappaB) and augments NK cell cytotoxicity. Our results suggest that curcumin most likely inhibits cell proliferation and cytokine production by inhibiting NF-kappaB target genes involved in the induction of these immune parameters.

Animals↗

PubMed2005

Phenolic acids in neem (Azadirachta indica): a major pre-existing secondary metabolites.

High Performance Liquid Chromatographic (HPLC) analyses of various parts (fresh and dry bark of stem, mature and tender leaves, flower and different parts of fruit, i.e., raw and ripe fruit epicarp, mesocarp and seed) of neem (Azadirachta indica), which occupies an important place in socio-cultural-religious life in Indian communities, indicate that neem is rich in pre-existing secondary metabolites (phenolic acids). Dry bark showed only tannic acid but in fresh bark three phenolic acids were observed, i.e., gallic, tannic, and ferulic acids. In tender leaves only gallic and ferulic acids were detected, but the levels of these phenolic acids in mature leaves were about three times and fifty times greater, respectively. Flowers had only two phenolic acids in which gallic acid was maximum followed by chlorogenic acid. The level of phenolic acid was maximum in seeds followed by epicarp and pulp. In raw and ripe fruit seeds four phenolic acids were detected. Raw fruit seeds were rich in phenolic acids than ripe fruit seeds. Fruit epicarp was relatively richer than seed, seed pulp and flowers of the plants. Neem flowers were also rich in gallic and chlorogenic acids.

Azadirachta↗

PubMed2004

Characterization of phenolic compounds in some Indian mango cultivars.

Mangoes (Mangifera indica) are rich in phenolic acids as detected by high-performance liquid chromatography. The phenolics have prominent medicinal properties. Among six important commercial mango cultivars (Deshi, Langra, Chausa, Mallika, Dashahari and Amrapali) tannic acid was maximal in Mallika, while gallic acid was maximal in Chausa and all other varieties. Caffeic acid was maximal in Langra followed by Chausa and Amrapali. Many of the pharmacological properties attributed to mango might be due to the presence of phenolic acids in fairly significant amounts.

Caffeic Acids↗

PubMed2004

Effect of glyphosate toxicity on growth, pigment and alkaline phosphatase activity in cyanobacterium Anabaena doliolum: a role of inorganic phosphate in glyphosate tolerance.

Response of glyphosate toxicity on photoautotrophic cyanobacterium A. doliolum and its mutant strain was investigated. Chlorophyll a content of both the wild type and mutant strain in the presence of glyphosate (N-phosphonomethyl glycine) initially showed an increasing trend when supplemented with Pi and a declining tendency under the Pi-starved condition. The results suggested that both the wild type and mutant strains were more sensitive to glyphosate in the absence of phosphate. Alkaline phosphatase activity of wild type strain in the presence of Pi, enhanced in response to addition of glyphosate (40 microg/ml), but the activity remained unaltered by addition of glyphosate in the Pi-starved cells, whereas the alkaline phosphatase activity in the mutant strain under both Pi-starved as well as unstarved conditions was stimulated (approximately 5.4 and 3.1-fold, respectively) by addition of glyphosate. The results on alkaline phosphatase activity indicated a glyphosate-induced depletion in the phosphate content of the cells, particularly in the mutant strain, as evident from the stimulated activity of alkaline phosphatase. It is suggested that enzyme activity in the Pi-starved wild type cells may not be influenced any further by glyphosate, as cellular phosphate reserve might not be available for further depletion.

Alkaline Phosphatase↗

PubMed2004

Investigation on the phenolics of some spices having pharmacotherapeuthic properties.

Spices are an important group of agricultural commodities being used by many civilizations all over the world to aid flavor, taste and nutritional values in the food. In traditional medical systems, their ability to heal various physical, mental and emotional problems has widely been reported. With this view, HPLC analysis was performed to estimate phenolic acids in 21 spices (asafetida, Bishop's weed, black mustard, coriander, cinnamon, clove, curry leaf, cumin black, cumin, fennel, fenugreek, garlic, ginger, Indian cassia, Indian dill or dill large cardamom, onion, saffron, tamarind, true cardamom, yellow mustard) commonly used in India in different forms. In all, 7 phenolic acids; viz., tannic, gallic, caffeic, cinnamic, chlorogenic, ferulic and vanillic acids could be identified on the basis of their retention time with standard compounds and co-chromatography. Several parts of the spices, for instance, seeds, leaves, barks, rhizomes, latex, stigmas, floral buds and modified stems were used in the study. Maximum amount of tannic and gallic acids was observed in black mustard and clove. Caffeic, chlorogenic and ferulic acids were found maximum in cumin while vanillic and cinnamic acids in onion seeds. The spices are known to significantly contribute to the flavor, taste, and medicinal properties of food because of phenolics.

Antioxidants↗

PubMed2003

Formation and size dependence of germanium nanoparticles at different helium pressures.

We report the formation of germanium nanoparticles and threadlike nanostructures by the process of thermal vapor deposition. Germanium was thermally evaporated and condensed on graphite substrates under varied ambient helium pressures of 100, 200, 300, and 400 torr. The deposited films were characterized through transmission electron microscopy. These investigations revealed the occurrence of germanium particles. The size of these particles varied inversely with ambient pressure. Whereas for an ambient pressure of 100 torr the average particle size was approximately 0.3-0.5 micron, for 400 torr the average size was approximately 30-60 nm. At high He pressure (e.g., approximately 400 torr), the nanoparticles that formed when annealed for 30 min at 200 degrees C in vacuum adopted threadlike nanostructures. A qualitative explanation has been put forward for the formation of germanium particles and variation of size of these particles with helium pressure in terms of condensation, collision, and coalescence.

Chemical Precipitation↗

PubMed2003

Local control of high-grade gliomas with limited volume irradiation versus whole brain irradiation.

INTRODUCTION: To evaluate the role of limited field radiation therapy in the management of high-grade gliomas and glioblastoma multiforme (GBM). MATERIAL AND METHODS: From July '96 to January '98, 50 newly diagnosed patients of high-grade gliomas (Grade III and IV) and glioblastoma multiforme who underwent surgery in the form of partial, sub-total or near-total excision as the primary treatment were enrolled in this study. The patients were randomized to receive two different postoperative external radiation protocols, Study Group A: Localized field external radiotherapy 50 Gy/25#/5 wks followed by Boost 10 Gy/5#/1 wk, Control Group B: Whole brain external radiotherapy 40 Gy/20#/4 wks followed by Boost 20 Gy/10#/2 wks by localized field. RESULTS: 20/25 (80%) patients in the study group and 14/25 (56%) patients in the control group showed improvement in their Karnofsky Performance Status (KPS). Thus a significant difference in the performance status was noted in favor of limited field irradiation. No significant difference in the local response was seen between the two groups after radiotherapy. Six months progression-free survival of the study group was 44% as compared to 26% in the control group. Six months overall survival was 66.67% in the study group and 50.72% in the control group (P<0.01). Maximum recurrences were noticed within 2 cm of the original tumor margin in both the groups. CONCLUSIONS: Although local control and survival of the patient in both the groups were same, performance status definitely improved in patients treated with localized field irradiation only.

Brain Neoplasms↗

PubMed2002

Transactivation of involucrin, a marker of differentiation in keratinocytes, by lens epithelium-derived growth factor (LEDGF).

Human involucrin (hINV), first appears in the cytosol of keratinocytes and ultimately cross-linked to membrane proteins via transglutaminase and forms a protective barrier as an insoluble envelope beneath the plasma membrane. Although the function and evolution of involucrin is known, the regulation of its gene expression is not well understood. An analysis of the hINV gene sequence, upstream of the transcription start site (-534 to +1 nt) revealed the presence of potential sites for binding of lens epithelium-derived growth factor (LEDGF); stress response element (STRE; A/TGGGGA/T) and heat shock element (HSE; nGAAn). We reported earlier that LEDGF activates stress-associated genes by binding to these elements and elevates cellular resistance to various stresses. Here, gel-shift and super-shift assays confirm the binding of LEDGF to the DNA fragments containing HSEs and STREs that are present in the involucrin gene promoter. Furthermore, hINV promoter linked to CAT reporter gene, cotransfected in human corneal simian virus 40-transformed keratinocytes (HCK), was transactivated by LEDGF significantly. In contrast, the activity of hINV promoter bearing mutations at the WT1 (containing HSE and STRE), WT2 (containing STRE) and WT3 (containing STRE) binding sites was diminished. In addition, in HCK cell over-expressing LEDGF, the levels of hINV mRNA and hINV protein are increased by four to five-fold. LEDGF is inducible to oxidants. Cells treated with 12-O-tetradecanoyl-phorbol-13-acetate (TPA), known to stimulate production of H(2)O(2), showed higher levels of LEDGF mRNA. Furthermore, our immunohistochemical studies revealed that hINV protein is found in the cytoplasm of HCK cells over-expressing LEDGF, but not detectable in the normal HCK cells or HCK cells transfected with vector. This regulation appears to be physiologically important, as over-expression of HCK with LEDGF increases the expression of the endogenous hINV gene and may provide new insight to understand the molecular mechanism of transcriptional regulation of this gene. LEDGF may play an important role in establishing an important barrier in corneal keratinocytes by maintaining epidermal turn-over rate, and protecting HCKs against stress.

Animals↗

PubMed2002

Plant growth-promoting rhizobacteria-mediated induction of phenolics in pea ( Pisum sativum) after infection with Erysiphe pisi.

Qualitative and quantitative estimation of phenolic compounds was done through high performance liquid chromatography (HPLC) in different parts of pea ( Pisum sativum) after treatment with two plant growth-promoting rhizobacteria (PGPR), viz., Pseudomonas fluorescens (strain Pf4) and Pseudomonas aeruginosa (referred to here as Pag) and infection by Erysiphe pisi. The phenolic compounds detected were tannic, gallic, ferulic, and cinnamic acids on the basis of their retention time in HPLC. In all the treated plants, synthesis of phenolic compounds was enhanced. The induction of gallic, ferulic, and cinnamic acids was manyfold more than those in the control. Maximum accumulation of phenolic compounds was observed in plants raised from PGPR-treated seeds and infection with E. pisi. Under pathogenic stress, Pag performed better because a relatively higher amount of phenolics was induced compared with plants treated with Pf4.

Ascomycota↗

PubMed2002

NaCl-induced oxidative damage in the cyanobacterium Anabaena doliolum.

Results obtained with graded concentrations of NaCl (20-200 m M) show decrease in the chlorophyll 'a' contents of Anabaena with increasing concentration of NaCl except at extremely low concentration of NaCl (5-20 m M). The rate of Hill activity and oxygen evolution are found to be stimulated by lower concentrations of NaCl, but not at higher concentrations of NaCl. Results have demonstrated that the O(2) evolution process is relatively more sensitive to NaCl stress than the Hill activity. Further, the results show NaCl induced an increase in the rate of RNO bleaching and loss of total thiol (-SH) contents. Taken together, these results suggest a NaCl-induced general oxidative stress. Results on the effect of oxygen radical quenchers reveal a predominant role of singlet oxygen in the NaCl-induced general oxidative stress as evident from a higher quenching effect of sodium azide than formate and histidine on the rate of RNO bleaching in Anabaena cells. However, the rate of lipid peroxidation and SOD activity show a declining pattern in response to increasing concentrations of NaCl. There is the possibility of a NaCl-induced decrease in the rate of lipid peroxidation when the SOD activity is also lower. But the NaCl-induced decline in the SOD activity does suggest that symptoms of general oxidative stress at elevated levels of NaCl are apparently owing to collapse of intracellular defense of the cells against the toxic oxygen radicals, not because of the higher rate of photosynthetic activity.

Anabaena↗

PubMed2002

MR findings of primary Ewing's sarcoma of greater wing of sphenoid.

Primary Ewing's sarcoma of the skull is a very rare entity. We report MRI findings in a case of Ewing's sarcoma of the greater wing of sphenoid in a 4-year-old patient. Magnetic resonance imaging showed markedly heterogenous signal intensity with areas of haemorrhage and necrosis. It also demonstrated the exact extent of tumour due to its multiplanar capabilities and was, therefore, helpful in planning surgery.

Child, Preschool↗

PubMed2002

Effect of naked neck gene (NA) and frizzle gene (F) on immunocompetence in chickens.

1. A total of 98 birds belonging to 4 genetic groups from two specialised populations--heterozygous naked neck (NA*NA/NA*N) and normally feathered (NA*N/NA*N) from one specialised population and heterozygous frizzle (F*F/F*N) and normally feathered (F*N/F*N) from another specialised population--were evaluated for general immunocompetence by assessing antibody response to SRBC, haemolytic complement level in the serum, in-vivo cell mediated immune (CMI) response to Concanavalin-A (Con-A) and a phagocytic index at 10-12 weeks of age. 2. The naked neck gene did not seem to influence the antibody response to SRBC, CMI to Con-A or the phagocytic index. However, significantly higher haemolytic complement level in serum was observed in birds carrying a copy of the NA mutation as compared to the normally feathered birds. 3. Similar trends were observed for the frizzle gene.

Animals↗

PubMed2002

Studies on exudate-depleted sclerotial development in Sclerotium rolfsii and the effect of oxalic acid, sclerotial exudate, and culture filtrate on phenolic acid induction in chickpea (Cicer arietinum).

Exudate depletion from developing sclerotia of Sclerotium rolfsii Sacc. in culture caused reduced size and weight of sclerotia. Germination of exudate-depleted sclerotia was delayed on Cyperus rotundus rhizome meal agar medium when compared with that of control sclerotia. The exudate-depleted sclerotia caused infection in chickpea (Cicer arietinum) plants in a glasshouse. Different temperatures and incubation periods had no effect on the germination ability of the exudate-depleted sclerotia. Oxalic acid, sclerotial exudate, and culture filtrate of S. rolfsii induced the synthesis of phenolic acids, including gallic, ferulic, chlorogenic, and cinnamic acids, as well as salicylic acid, in treated chickpea leaves. Gallic acid content was increased in treated leaves compared with the untreated controls. Maximum induction of gallic acid was seen in both leaves treated with oxalic acid followed by exudate and leaves treated with culture filtrate. Cinnamic and salicylic acids were not induced in exudate-treated leaves. Ethyl acetate fractionation indicated that the sclerotial exudates consisted of gallic, oxalic, ferulic, chlorogenic, and cinnamic acids, whereas the culture filtrate consisted of gallic, oxalic, and cinnamic acids along with many other unidentified compounds.

Basidiomycota↗