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Biomedical subjects

P K Bhatnagar

Publications and source records attributed to P K Bhatnagar.

49 records · Page 3Linked to original sources
PubMed1981

Interactions between polymerized human albumin, hepatitis B surface antigen, and complement: II. Involvement of Clq in or near the hepatitis B surface antigen receptor for polyalbumin.

A species-specific receptor for polymerized human albumin (PHALB) has been reported on hepatitis B surface antigen (HBsAg)-carrying particles. Our previous observations that human Clq also binds PHALB in a species-restricted manner led us to investigate the possibility that HBsAg-associated Clq is involved in the PHALB receptor on HBsAg particles. The temperature, ionic strength, and pH requirements necessary for binding of PHALB to both Clq and HBsAg were compared and found to be similar. Normal human serum and purified Clq inhibited the PHALB-HBsAg interaction; the inhibition was markedly reduced in heat-inactivated and Clq-depleted serum. Heat-denatured or reduced and alkylated Clq failed to inhibit the PHALB-HBsAg binding. Moreover, human Clq was found to be present in purified preparations of HBsAg and the quantity detected paralleled the degree of PHALB-HBsAg binding. While anti-Clq inhibited the PHALB-HBsAg interaction, anti-Clr, - Cls, -C3, and -Ig were not inhibitory. Collagenase treatment of purified HBsAg reduced both PHALB-binding activity and the degree of HBsAg-associated Clq. These observations provide evidence that HBsAg-associated Clq is involved in or near the HBsAg-binding site for PHALB.

Blood↗
PubMed1977

The effect of rifampicin on the developmental phases of germinating spores of Clostridum sp., MSp+.

The effect of rifampicin on the developmental phases of germinating spores of Clostridium botulinum, MSp+, has been studied. At sublethal concentrations of rifampicin (0.05 ng/ml) the time periods required for outgrowth and vegetative growth was significantly prolonged because of the inhibition of RNA and protein synthesis. However, rifampicin had essentially no effect on DNA synthesis or on subsequent spore formation. Chemical analyses showed that the amount of protein present in vegetative cells of the rifampicin-treated cultures was twice as great as in the untreated cultures but the total protein content of endospores was the same in both cases. It was revealed in ultrastructural studies of rifampicin (0.1 ng/ml) treated cultures, examined after 22 h, that septum formation and normal cell division of the emerging cell was blocked and a few cells showed constriction which produced one normal and one protoplast-like daughter cell.

Bacterial Proteins↗
PubMedDate not supplied

Efficacy of the hematoregulatory peptide SK&F 107647 in experimental systemic Candida albicans infections in normal and immunosuppressed mice.

SK&F 107647, a novel synthetic dimeric pentapeptide, has been shown to be a potent hematoregulatory agent. The potential for the hematoregulatory factors elicited by SK&F 107647 to confer protection in experimental models of systemic Candida albicans infection was evaluated in immunosuppressed and immunocompetent mice. Prophylactic treatment with recombinant human interleukin-1 (rhIL-1), recombinant human granulocyte colony stimulating factor (rhG-CSF), or the hematoregulatory peptide SK&F 107647 significantly increased survival times in gamma irradiated immunosuppressed as well as non-irradiated immunocompetent mice challenged with a lethal dose of C. albicans. Protection was also observed in athymic nu/nu "nude" mice. Additionally, significant increases in survival in non-irradiated immunocompetent mice dosed by oral gavage were observed. These results indicate that SK&F 107647 can significantly enhance natural host resistance to experimental C. albicans infections both in immunosuppressed and immunocompetent mice.

Animals↗
PubMedDate not supplied

The application of an improved solid phase synthetic technique to the delineation of an antigenic site of apolipoprotein A-II.

Previous studies have shown that the antigenic sites of human plasma high-density apolipoprotein A-II (apoA-II) are separate from their lipid-binding determinants in human high density lipoproteins (HDL). A specific radioimmunoassay has shown that three distinct antigenic sites are located in residues 4-23, 31-46, and 56-77; these studies suggested that an antigenic site might be restricted to residues 60-77 in the 56-77 fragment. To further delineate this site, we have developed a solid phase radioimmunoassay technique using an improved solid support on which selected sequences of peptides were synthesized, deprotected with HF, and the resulting peptidyl-resins tested for their capability of binding purified 125I-anti-apoA-II antibodies. Amino acid analyses and solid phase sequence analyses were performed to verify the sequence of the synthetic peptide on the solid support. Using this technique, 125I-anti-apoA-II antibodies had achieved 50% of maximal binding when residues 61-77 were attached to the solid support. The maximal binding was achieved by the addition of one more residue, Leu60, thus confirming our suggestion that a major antigenic site is located in residues 60-77. The binding to the peptidyl-resin was inhibited by a synthetic fragment corresponding to residues 60-77 indicating that the antibodies were specifically bound to the resin.

Amino Acid Sequence↗
PubMedDate not supplied

CGRP stimulates the adhesion of leukocytes to vascular endothelial cells.

Calcitonin gene-related peptide (CGRP) stimulates the adhesiveness of human umbilical vein endothelial cells for U937 cells and human neutrophils in a dose- and time-dependent manner. The onset of CGRP-induced adhesives of HUVEC was rapid (30 min), independent of protein synthesis, and lasted over 24 h in the continuous presence of the peptide. The stimulatory effect of CGRP was completely blocked by the CGRP antagonist, CGRP(8-37). The present study provides evidence in support of the potential role of sensory nerve-derived neuropeptides in the modulation of leukocyte adhesion to vascular endothelial cells.

Calcitonin Gene-Related Peptide↗
PubMedDate not supplied

Liquid chromatographic determination of gentamicin in serum with spectrophotometric detection.

A simple, accurate, and specific liquid chromatographic procedure is described for the determination of gentamicin in 50 muL of serum. Gentamicin and sisomicin (IS) were converted into their trinitrophenyl derivatives by reaction with a water soluble derivatizing agent at 70 degrees C for 30 minutes. The derivatives were extracted from the crude mixture with chloroform, which was separated, evaporated, and the residue reconstituted in acetonitrile. Gentamicin was separated into three major isomers (C1, C2, and C1a) on a reversed-phase octyl column by eluting with a mobile phase. The eluted compounds were detected at 340 nm and quantified from their peak heights or peak areas. Chromatography was complete in less than 11.0 minutes. The lower limit of detection for gentamicin was less than 0.5 mg/L, analytical recoveries varied from 96.6% to 99.3%, linearity extended to 15.0 mg/L, and day-to-day precision was between 2.2% to 2.9%.

Chromatography, Liquid↗
PubMedDate not supplied

Thrombolysis of peripheral graft occlusion in patients with hypertension.

The objective of this study was to evaluate the effect of hypertension on the use of thrombolytic therapy in patients with occluded synthetic peripheral bypass grafts. Thrombolysis with urokinase was performed in 44 cases of occluded lower extremity bypass grafts. The cases were divided into two groups: Group I consisted of patients currently being treated for hypertension. Group II consisted of patients without a history of hypertension. A comparison of pre- or intra-lytic data revealed that there was no significant difference in each group. Complications occurred in 15 (32.6%) out of 46 cases. There was no significant increase in complication when the risk factors were compared. In Group I, the one, two, and three year patency rates were 42.7%, 23.0%, and 7.7% and the limb salvage rates were 93.3%, 73.9%, and 73.9% for one, two, and three years respectively. The Group II patency rates were 70.6%, 41.6%, and 41.6% and the limb salvage rates were 94.1%, 86.9%, and 86.9%. The patency rate was significantly reduced when Group I was compared to Group II (p < 0.05). There was no statistically significant difference in limb salvage rates between Groups I and II. In conclusion, hypertension is one of the important risk factors that reduce the patency rate after thrombolytic therapy in patients with peripheral arterial bypass graft.

Aged↗