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Biomedical subjects

P Singh

Publications and source records attributed to P Singh.

At least 73 records · Page 4Linked to original sources
PubMed2003

Comparative studies of global migration levels of recycled vs virgin polyethylene for packing and storage of milk.

The use of Low-density polyethylene (LDPE) is increased for packaging and storage of food, milk etc. Virgin polyethylene is safe due to non-toxic, inertness and insoluble in milk. It is a replacement of conventional bottle packing of milk. Detection of contamination of milk contact of LDPE film in which milk was packed is being done by global migration method. LDPE films developed by well known technique i.e. Blown film extrusion technique, containing different ratio of virgin-recycled polyethylene materials as well as additives such antioxidants, filler, colourant etc. The impact of above LDPE films on the quality of milk was studied by global migration testing. After analyzing the observed results, it is found that the values of global migration increase with increase in percentage of recycled granules and percentage and type of additives in the film.

Animals↗
PubMed2002

Progastrin1-80 stimulates growth of intestinal epithelial cells in vitro via high-affinity binding sites.

Proliferation and carcinogenesis of the large intestinal epithelial cells (IEC) cells is significantly increased in transgenic mice that overexpress the precursor progastrin (PG) peptide. It is not known if the in vivo growth effects of PG on IEC cells are mediated directly or indirectly. Full-length recombinant human PG (rhPG(1-80)) was generated to examine possible direct effects of PG on IEC cells. Surprisingly, rhPG (0.1-1.0 nM) was more effective than the completely processed gastrin 17 (G17) peptide as a growth factor. Even though IEC cells did not express CCK(1) and CCK(2) receptors (-R), fluorescently labeled G17 and Gly-extended G17 (G-Gly) were specifically bound to the cells, suggesting the presence of binding proteins other than CCK(1)-R and CCK(2)-R on IEC cells. High-affinity (K(d) = 0.5-1.0 nM) binding sites for (125)I-rhPG were discovered on IEC cells that demonstrated relative binding affinity for gastrin-like peptides in the order PG >or= COOH-terminally extended G17 >or= G-Gly > G17 > *CCK-8 (* significant difference; P < 0.05). In conclusion, our studies demonstrate for the first time direct growth effects of the full-length precursor peptide on IEC cells in vitro that are apparently mediated by the high-affinity PG binding sites that were discovered on these cells.

Amino Acids↗
PubMed2002

Impact of self-assembled surfactant structures on rheology of concentrated nanoparticle dispersions.

Rheological behavior of surfactant-stabilized colloidal dispersions of silica particles under extreme conditions (low pH, high ionic strength) has been investigated in relation to interparticle forces and stability of the dispersion. The surfactant used as the dispersing agent was C(12)TAB, a cationic surfactant. Stability analysis through turbidity measurements indicated that there is a sharp increase in the stability of the dispersion when the surfactant concentration is in the range of 8 to 10 mM in the system. The state of the dispersion changes from an unstable regime to a stable regime above a critical concentration of C(12)TAB in the system. In the case of interaction forces measured between the silica substrate and AFM tip, no repulsive force was observed up to a surfactant concentration of 8 mM and a transition from no repulsive forces to steric repulsive forces occurred between 8 and 10 mM. Rheological measurements as a function of C(12)TAB concentration indicated a significant decrease in the viscosity and linear viscoelastic functions of the dispersion over the same range of surfactant concentration (8 to 10 mM C(12)TAB), showing a strong correlation between the viscosity behavior, interparticle forces, and structure development in the dispersion.

Journal Article↗
PubMed2002

Quantitative structure-activity relationship study of 2-arylsulfonyl-6-substituted benzonitriles as non-nucleoside reverse transcriptase inhibitors of HIV-1.

The reverse transcriptase inhibition of HIV-1, the most common form of HIV, by non-nucleoside 2-arylsulfonyl-6-substituted benzonitriles is analysed through Fujita-Ban and Hansch approaches. The analyses have helped to ascertain the role of different substituents in explaining the observed inhibitory actions of these compounds. From both approaches it appeared that SO2 instead of SO or S at X; and NH2 instead of F at Y (see Figure 1) are advantageous to improving the activity of a compound against HIV-1. This in turn leads to the suggestion that the 2-arylsulfonyl-6-aminobenzonitrile scaffold is the only appropriate structural entity that may further result into potential compounds. Further, the compounds having a OMe substituent at the orthoposition, the bulkier substituents at meta-positions and "no" substituent at para-position of 2-arylsulfonyl moiety are beneficial in raising the activity. The two quantitative structure-activity relationship (QSAR) analyses, differing in parametric approach, therefore, provided the grounds for rationalizing the substituent selection in designing more potent compounds of the series.

Anti-HIV Agents↗
PubMed2002

Successful treatment of pulmonary artery aneurysms secondary to possible Behçet's disease.

Pulmonary artery aneurysm (PAA) secondary to Behçet's disease (BD) is a rare condition. The commonest presentation is hemoptysis, which can be fatal. Though the classical triad of recurrent oral and genital ulcers and relapsing iritis is present in most patients of BD, isolated pulmonary artery involvement termed as incomplete BD has been reported. Prompt diagnosis and immunosuppressive therapy can cause regression of aneurysm and prevent fatal hemoptysis. We report a case of PAA due to BD who presented with hemoptysis and responded to steroid therapy.

Adult↗
PubMed2002

Scorpion envenomation causing hemiparesis.

We report a case of scorpion sting who presented with right hemiparesis and deranged level of consciousness. Prolonged BT/CT, decreased platelet counts, prolongation of PT and APTT with positive fibrinogen degradation products (FDP) D-dimer and CT scan findings of multiple cerebral haemorrhagic infarct indicating the presence of disseminated intravascular coagulation (DIC) as a cause of hemiparesis. Patient was managed with fresh blood transfusion and conventional treatment with favourable outcome.

Adult↗
PubMed2002

pH-sensitive liposomes: mechanism of triggered release to drug and gene delivery prospects.

A growing amount of literature describes the development and applications of novel targeting and/or release triggering schemes to improve the therapeutic index of drugs encapsulated within liposomes. The composition of liposomal systems can be modified to facilitate site specific release in response to environmental conditions, namely at the gross anatomical level, at the cellular or sub-cellular level. They are designed in order to release their contents in response to acidic pH within the endosomal system while remaining stable in plasma thus improving the cytoplasmic delivery of various polar materials and macromolecules such as anti-tumor drugs, toxins, proteins and DNA. This review covers various aspect of research on pH-sensitive liposomes.

Animals↗
PubMed2002

Effect of melatonin and beta-carotene on indomethacin induced gastric mucosal injury.

The study was conducted to examine the role of free radicals in Indomethacin induced gastric mucosal injury and to evaluate the gastroprotective effects of melatonin and beta-carotene. Gastric mucosal injury was produced in rats by administering indomethacin 30 mg/kg subcutaneously. Melatonin was administered in three different doses of 5, 10 and 20 mg/kg, 30 minutes prior to the administration of indomethacin. Beta-carotene was administered as a single dose of 100 mg/kg. Following parameters were calculated: ulcer index, lipid peroxidation and antioxidant defense enzymes i.e. superoxide dismutase, glutathione peroxidase and catalase. Indomethacin caused gastric mucosal injury in the form of haemorrhages, increased the lipid peroxidation and decreased the levels of the antioxidant defense enzymes. Melatonin (20 mg/kg) and beta-carotene decreased the ulcer index and lipid peroxidation, and reduced the decrease in antioxidant enzyme levels. These findings suggest the melatonin and beta-carotene show protective effect against indomethacin induced gastric injury and this effect is mediated by scavenging of oxygen derived free radicals.

Animals↗
PubMed2002

Leeds procedure--a treatment modality for scoliosis.

The present study comprises of forty patients of scoliosis in growing age group (10-25 years) with Cobbs angles ranging from 52"-98". They were treated with Leeds procedure which is by anterior loosening followed by Posterior Harrington fixation + Luque derotation + Fusion and Costoplasty. Majority of the curves were thoracic (60%), and right sided (72%). Average correction of the deformity after surgery was 45%. Satisfaction level of patients and parents was good in 60% of the cases. The modality of treatment was decided on the basis of personality of each case, its demand and requirement, time of presentation and the potential for increasing severity. Anterior spinal surgery for scoliosis is an effective procedure in hands of experienced surgeons and it reduces stiffness of the curve, shorten the anterior column, decreases thoracic lordosis which leads to some improvement of pulmonary function. But there is greater risk of damage to vital structures with higher risks of cardiorespiratory failure. The potential risks have to be balanced with the expected rewards. The optimum method of correction has to be decided by careful preoperative evaluation. Combined procedure of anterior and posterior surgery causes lesser decrease in pulmonary functions than costoplasty alone, and achieving better cosmetic correction. This study reaffirms the role of anterior spinal surgery in India as the patients due to lower levels of health awareness present late and with severe deformities.

Adolescent↗
PubMed2001

De novo initiation of viral RNA-dependent RNA synthesis.

RNA viruses use several initiation strategies to ensure that their RNAs are synthesized in appropriate amounts, have correct termini, and can be translated efficiently. Many viruses with genomes of single-stranded positive-, negative-, and double-stranded RNA initiate RNA synthesis by a de novo (primer-independent) mechanism. This review summarizes biochemical features and variations of de novo initiation in viral RNA replication.

Flaviviridae↗
PubMed2001

Intraspecific comparisons reveal differences in the pattern of ultraviolet radiation responses in four maize (Zea mays L.) varieties.

Four maize (Zea mays L.) varieties were examined for ultraviolet radiation-induced changes in leaf rolling, biomass, fluctuating leaf asymmetry and DNA damage. Short-term dose-response curves for each response were constructed and responses in each line compared. The four varieties each exhibited a different pattern of tolerance and reactivity, ranging from B73, which was tolerant in all four measures, to TS1, which was affected in DNA damage levels and leaf rolling but unaffected in biomass accumulation and fluctuating leaf asymmetry. The pattern of ultraviolet radiation responses allows us to narrow the possibilities for the source of the defect in reactive varieties. The four varieties tested include inbred parents that have been used to construct recombinant inbred lines and a variety that is found in the background of the engineered RescueMu transposon mutagenesis lines. These dose-response curves and variety comparisons provide the foundation for genetic dissection of the mechanisms of ultraviolet radiation responses in maize.

Biomass↗
PubMed2001

Retinoblastoma protein is functionally distinct from its homologues in affecting glucocorticoid receptor-mediated transcription and apoptosis.

The cell cycle regulator, retinoblastoma protein, is known to potentiate glucocorticoid receptor-activated transcription through the interaction of its pocket domain with the transcription coactivator, hBRM. We now show that glucocorticoid receptor-induced apoptosis is also dependent on both the retinoblastoma protein and hBRM. p107 and p130, which share extensive sequence homology with the pocket domain of the retinoblastoma protein but not its N-terminal region, also interact with hBRM but do not support either glucocorticoid receptor-dependent activity. This difference arises from the divergent N-terminal domain of the retinoblastoma protein, which, when fused to the pocket domains, confers upon p107 and p130 the ability to influence glucocorticoid receptor activities. This effect probably results from the promotion of glucocorticoid receptor-targeted chromatin remodeling by the hBRM-containing SWI/SNF complex because the N-terminal domain of the retinoblastoma protein enhances glucocorticoid receptor-hBRM interactions. These results highlight that, besides the interaction between hBRM and the pocket domain of RB, the N-terminal region of the retinoblastoma protein is also essential for glucocorticoid receptor-induced apoptosis and the potentiation of glucocorticoid receptor-mediated transcription and provide a basis for functional distinction between the retinoblastoma protein and its homologues.

Apoptosis↗