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Biomedical subjects

R K Sood

Publications and source records attributed to R K Sood.

At least 19 recordsLinked to original sources
PubMed1999

Substrate/inhibition studies of bacteriophage T7 RNA polymerase with the 5'-triphosphate derivative of a ring-expanded ('fat') nucleoside possessing potent antiviral and anticancer activities.

As part of an effort to explore the mechanism of potent, broad spectrum antiviral and anticancer activities of a number of ring-expanded ('fat') nucleosides that we recently reported, a representative 'fat' nucleoside 4,6-diamino-8-imino-8H-1-beta-D-ribofuranosylimidazo[4,5-e][1,3]di azepine (1) was converted to its 5'-triphosphate derivative (2), and biochemically screened for possible inhibition of nucleic acid polymerase activity, employing synthetic DNA templates and the bacteriophage T7 RNA polymerase as a representative polymerase. Our results suggest that 2 is a moderate inhibitor of T7 RNA polymerase, and that the 5'-triphosphate moiety of 2 appears to be essential for inhibition as nucleoside 1 alone failed to inhibit the polymerase reaction.

Antineoplastic Agents↗
PubMed1998

Streptococcus pneumoniae type 14 polysaccharide-conjugate vaccines: length stabilization of opsonophagocytic conformational polysaccharide epitopes.

A simple and convenient method was developed for the preparation of Streptococcus pneumoniae type 14 polysaccharide (Pn14PS)-tetanus toxoid (TT) conjugate vaccines, using terminally linked Pn14PS fragments of different lengths. Native Pn14PS was simultaneously depolymerized and activated for conjugation by partial N-deacetylation followed by nitrous acid deamination which yielded fragments (1.4 to 150.0 kDa) having a free aldehyde at the reducing end. These were then conjugated to TT through their terminal aldehydic groups, using the reductive amination procedure. All of the above conjugates, when injected in rabbits, induced anti-Pn14PS antibodies, whereas the native Pn14PS did not. The amounts of anti-Pn14PS antibodies elicited by these conjugates, as determined by enzyme-linked immunosorbent assay, followed a trend with conjugates containing the highest-molecular-weight Pn14PS eliciting the highest titers. The same trend was also observed in the ability of the antibodies to opsonize and kill live type 14 pneumococci, although the increase in opsonophagocytic activity was more pronounced and did not correlate linearly with increases in antibody titer. Competitive inhibition of the binding of different conjugate antisera to the native Pn14PS, using Pn14PS fragments as inhibitors, established that the conjugates induced antibodies with specificities for different lengths of Pn14PS beginning at 2 repeating units (RU). It was also established, both immunologically and antigenically, that at least 4 RU of Pn14PS were required to form an extended conformational epitope and that approximately 22 RU of Pn14PS were required to duplicate the same epitope on the same saccharide chain. The conformational epitope was found to be essential for the induction of antibodies with high opsonophagocytic activity and that augmentation of opsonophagocytic activity was also dependent on further chain extension.

Animals↗
PubMed1998

Capsular polysaccharide-protein conjugate vaccines and intravenous immunoglobulins.

Capsular polysaccharides (CPs), present on the surface of most pathogenic bacteria, have been recognised as virulence factors. Antibodies specific to these polysaccharides can mediate the killing of these bacteria by phagocytes in the presence of complement. The conjugation of polysaccharides to carrier proteins enhances their immunogenicity and renders the immune response T-cell dependent. The currently licensed capsular polysaccharide vaccines and polysaccharide-protein conjugate vaccines under development for the prevention of bacterial infections will be discussed in this review. Use of these vaccines for active vaccination and for the vaccination of healthy plasma donors to produce hyperimmune iv. immunoglobulins for the passive immunisation of appropriate patient populations is also discussed.

Journal Article↗
PubMed1998

Awareness of hypertension among a north Indian population.

Developing countries are going through a demographic transition. Non-communicable diseases like hypertension are emerging in epidemic proportions. Education and awareness among people is the key to reduce the burden of the disease. To see the levels of awareness and characteristic of aware and unaware hypertensives, 7630 employees in Shimla town were screened for hypertension. Hypertension was detected in 2535 cases of which 559 (22.05%) were aware. The aware hypertensives were predominantly symptomatic and had higher age and blood pressure than the unaware hypertensives. The aware hypertensives were predominantly overweight. This low level of awareness highlights the need for a comprehensive hypertension education programme to be taken up at the national level.

Adult↗
PubMed1997

The synthesis of Streptococcus pneumoniae polysaccharide-tetanus toxoid conjugates and the effect of chain length on immunogenicity.

To study the relationship between length of pneumococcal polysaccharide and immunologic performance in rabbits we took well defined fragments of the capsular polysaccharides of S. pneumoniae types 3, 6A, 18C, 19F and 23F and pneumococcal C-polysaccharide and linked them terminally by reductive amination to tetanus toxoid. Contrary to other reports we found little variation in antibody titers with increasing length. In general the opsonophagocytic titers determined using activated HL60 cells and rabbit peritoneal cells correlated well with the antibody titers except for that of type 3, which despite the presence of high polysaccharide antibody titers gave unexpectedly low opsonophagocytic titers. The C-polysaccharide-conjugate was also immunogenic when injected in both rabbits and mice but gave low opsonophagocytic titers. It was demonstrated that opsonophagocytosis was solely dependent on the presence of phosphoryl choline-specific antibody and that the induction of these antibodies was species dependent.

Animals↗
PubMed1996

An epidemiological study of obesity in Shimla Town.

A cross sectional study of 888 randomly selected subjects in Shimla town was done to determine prevalence of obesity, its relation to age and physical activity. The prevalence of obesity was 21.5% using cut off levels of BMI 25. The prevalence of obesity rose significantly with age. Obesity was less in those having moderate physical activity as compared to those with low and high activity. Primary prevention is required to tackle this disease risk factor through health education focussing on promotion of moderate regular physical activity.

Adult↗
PubMed1992

Structures of the glycopeptidolipid antigens of serovars 25 and 26 of the Mycobacterium avium serocomplex, synthesis of allyl glycosides of the outer disaccharide units and serology of the derived neoglycoproteins.

The pentasaccharide hapten released from the glycopeptidolipid (GPL) antigen of M. avium serovar 26 has been characterized as O-(2,4-di-O-methyl-alpha-L-fucopyranosyl)-(1-->4)- O-beta-D-glucopyranosyluronic acid-(1-->4)-O-(2-O-methyl-alpha-L-fucopyranosyl)-(1-->3)-alpha-L- rhamnopyranosyl-(1-->2)-6-deoxy-L-talose. The allyl glycosides of the outer glycosyl and glycobiosyl units of this hapten have been synthesized, the latter by a route involving oxidation of the corresponding D-glucopyranose derivative. Conjugation of allyl glycosides to protein by ozonolysis and reductive coupling afforded neoantigens (neo 26-1 and 26-2), both of which interacted with antibodies to M. avium serovar 26. The terminal sugar residue of the pentasaccharide hapten of the serovar 25 GPL had been shown to have the galacto configuration on the basis of 1H-13C NMR correlation spectroscopy, but absolute configurational assignment for the sugar awaited the synthesis, as for neo 26, of two glycobiosyl NGPs bearing the terminal sugar in the D and L enantiomeric forms, respectively. Only the glycobiosyl NGP bearing the terminal sugar as the D-enantiomer interacted with antibodies to M. avium serovar 25, thus providing evidence for the absolute configuration of the sugar, and showing that the complete oligosaccharide hapten has the structure, O-(4-acetamido-4,6-dideoxy-2-O-methyl-alpha-D- galactopyranosyl)-(1-->4)-O-beta-D-glucopyranosyluronic acid-(1-->4)-O-(2-O-methyl-alpha-L-fucopyranosyl)-(1-->3)-O-alpha-L- rhamnopyranosyl-(1-->2)-6-deoxy-L-talose.

Allyl Compounds↗
PubMed1992

Long-term effects of gastric surgery for treating respiratory insufficiency of obesity.

The Pickwickian syndrome can be divided into two primary breathing disorders, which can affect patients alone or in combination: sleep apnea syndrome (SAS) and obesity hypoventilation syndrome (OHS). Between 1980 and 1990, 126 patients with respiratory insufficiency underwent gastric surgery for morbid obesity, 12.5% of the entire series. These patients weighed more (164 +/- 36 vs 135 +/- 25 kg, P less than 0.0001) and were more often men (62% vs 14%, P less than 0.001) than those without pulmonary dysfunction. Sixteen had OHS alone, 65 had SAS alone, and 45 had both. Of those with OHS, 38 have been followed for 5.8 +/- 2.4 y since surgery and 29 are currently asymptomatic. In the 12 patients in whom arterial blood gases were available greater than 5 y since surgery, the PaO2 increased from 54 +/- 10 to 68 +/- 20 mm Hg (P less than 0.0001) and PaCO2 fell from 53 +/- 9 to 47 +/- 11 mm Hg (P = 0.05). Of the 110 patients with SAS, 57 were available for follow-up an average of 4.5 +/- 2.3 y since surgery and 38 were completely asymptomatic, 15 had mild SAS, and 4 had both SAS and OHS. In 40 patients with pre- and post-weight reduction sleep polysomnograms, the sleep apnea index fell from 64 +/- 39 to 26 +/- 26 (P less than 0.0001). Although respiratory insufficiency of obesity patients had a higher operative mortality than did patients without pulmonary dysfunction (2.4% vs 0.2% after gastric bypass), weight loss was associated with significant improvements in sleep apnea, arterial blood gases, pulmonary hypertension, left ventricular dysfunction, lung volumes, and polycythemia.

Adult↗
PubMed1991

Structure of the glycopeptidolipid antigen of serovar 20 of the Mycobacterium avium serocomplex, synthesis of allyl glycosides of the outer di- and tri-saccharide units of the antigens of serovars 14 and 20, and serology of the derived neoglycoproteins.

The tetrasaccharide hapten released from the glycopeptidolipid (GPL) antigen of Mycobacterium avium serovar 20 has been characterized as O-(2-O-methyl-alpha-D-rhamnopyranosyl)-(1----3)-O-(2-O-methyl-alpha-L- fucopyranosyl)-(1----3)-alpha-L-rhamnopyranosyl-(1----2)-6-deoxy-L-talos e. Syntheses are reported of allyl glycosides of the outer disaccharide unit of this hapten, O-(2-O-methyl-alpha-D-rhamnopyranosyl)-(1----3)-2-O-methyl-alpha-L-fu copyranose , and also of the outer di- and tri-saccharide units of the GPL antigen of M. avium serovar 14, O-(N-formyl-alpha-L-kansosaminyl)-(1----3)-2-O-methyl-alpha-D-rham nopyranose and O-(N-formyl-alpha-L-kansosaminyl)-(1----3)-O-(2-O-methyl-alpha-D- rhamnopyranosyl)-(1----3)-2-O-methyl-alpha-L-fucopyranose. The key steps in the latter synthesis involve the preparation of allyl 4-azido-4,6-dideoxy-3-C-methyl-2-O-methyl-alpha-L-mannopyranoside as a precursor for the N-formylkansosamine unit, followed sequentially by conversion into and use of a trichloroacetimidate as glycosyl donor for di- and tri-saccharide formation, O-deacylation, reduction, and N-formylation. The allyl glycosides, representative of the haptens from both serovars, have been converted into neoglycoproteins (NGPs) and their serological activities have been compared in the light of the structural relationship between them.

Antigens, Bacterial↗
PubMed1989

Breast metastasis from a pharyngeal carcinoma.

The reported incidence of metastatic disease in head and neck cancer is increasing. The most common site of metastatic involvement in squamous carcinoma of the head and neck is the lung followed by liver, mediastinal nodes and bone. The breast is rarely infiltrated by metastatic disease, 2 per cent or less of clinically detected breast lumps being of non-mammary origin, most frequently malignant melanoma, lymphoma/leukaemia and primary lung carcinoma. A 73-year-old female presented with a primary posterior pharyngeal wall squamous carcinoma and bilateral enlarged neck nodes. She developed an isolated breast metastasis while receiving palliative radiotherapy and died seven months after presentation. Clinically detected breast metastasis in head and neck squamous cell carcinoma was first documented by Toombs and Kalisher in 1977. This is the first report of such a case originating in the posterior pharyngeal wall. The prognosis is invariably poor.

Aged↗