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Biomedical subjects

S K Agarwal

Publications and source records attributed to S K Agarwal.

At least 19 recordsLinked to original sources
PubMed1992

Structure of lansimide 2, a product from Clausena lansium.

The natural product lansimide 2 is a 1:1 mixture of two different cyclic amides, C18H17NO2.C18H19NO3. The mixture crystallizes as a molecular pair in the centrosymmetric space group P21/n. M(r) = 576.69, monoclinic, a = 20.151 (2), b = 6.2984 (4), c = 24.051 (2) A, beta = 104.339 (8) degrees, V = 2957.4 A3, Z = 4, Dx = 1.30 g cm-3, Cu K alpha, lambda = 1.54178 A, mu = 6.1 cm-1, F(000) = 1224, T = 163 (1) K, R = 0.033, wR = 0.034 for 5002 observed reflections.

Lactams↗
PubMed1992

Interaction of putative neurotransmitters in rostral ventrolateral medullary cardiovascular neurons.

As recent immunohistochemical evidence has shown the coexistence of putative neurotransmitters in the rostral ventrolateral medulla (RVLM), we have investigated the possibility that there may be an interaction of putative transmitters on the firing frequency of cardiovascular neurons in the RVLM. Extracellular activity was recorded from 37 spontaneously firing units in the right RVLM of urethane anaesthetized and artificially ventilated rats. Nine of these units were classified as cardiovascular neurons because: (i) they were silenced by baroreceptor activation (1-3 micrograms phenylephrine i.v.); and (ii) they showed rhythmicity of their spontaneous activity in synchrony with the cardiac cycle. Microiontophoresis of combinations of near threshold amounts of L-glutamate (GLU; 10 nA), acetylcholine (Ach; 30 nA) and substance-P (SP; 60 nA) showed a synergistic interaction of these substances with one another in eliciting changes in firing frequency of cardiovascular neurons. These results show that GLU and Ach, GLU and SP and Ach and SP interact synergistically to influence the firing frequency of cardiovascular neurons in the RVLM and suggest that these substances play a physiological role in the neural control of the circulation.

Acetylcholine↗
PubMed1992

Early evidence of beneficial effects of chordal preservation in mitral valve replacement on left ventricular dimensions.

Earlier authors have shown the improved left ventricular (LV) function after chordae-preserving mitral valve replacement (MVR) in follow-up studies. Seventy-nine consecutive patients undergoing MVR were studied preoperatively and pre-discharge with M-mode and two-dimensional Color Doppler echocardiography for early LV morphometric changes. Conventional MVR was performed in 42 patients (Group 1) and the posterior leaflet-chordae-papillary muscle complex was preserved in 37 patients (Group 2). Both cohorts were similar in age, sex, preoperative NYHA class and valve pathology. Four St. Jude bioprostheses, 9 Medtronic and 66 Sorin prostheses were implanted. The intraoperative and perioperative management protocol was uniform for both groups. The median left atrial dimension in both groups decreased to better physiological levels (53 to 46 mm in group 1, 52.5 to 46 mm in group 2). The median LV enddiastolic dimension increased from 47 to 48 mm in group 1 while it decreased from 56.5 to 49 min in group 2. The median LV endsystolic dimension remained unchanged in group 1 but decreased in group 2 (37.6 to 36 mm). Echocardiographic documentation of such early changes in the LV dimensions after modified MVR indicates that the beneficial effects of chordal preservation become evident early in the postoperative period and may explain the improved perioperative LV function after modified MVR compared to conventional MVR.

Adolescent↗
PubMed1992

Structure-activity relationship in buffalo spleen cathepsin B.

Effect of pH, urea, and guanidine hydrochloride on the activity and structure of buffalo spleen cathepsin B was investigated. At alkaline pH, there was an irreversible loss of the structure as well as the activity of the buffalo enzyme. At acidic pH, however, the inactivation of the enzyme was reversible. The enzyme reversibly lost most of its activity at denaturant concentrations which did not cause a significant change in its secondary structure. The inactivation could be attributed to minor perturbations in the environment of the amino acid residue(s) at and/or around the active site of the enzyme. High urea/guanidine hydrochloride concentrations leading to the structural changes in cathepsin B made the inactivation process irreversible.

Animals↗
PubMed1992

Salting-out behaviour of the domains of ovomucoid.

The solubility of ovomucoid and of four fragments comprising domain I, I+II, and III of the protein in concentrated ammonium sulphate solution were studied at different pHs (25 degrees C) and at various temperatures (pH 7.0), and the salting-out parameters Ks and beta were determined for the five proteins. The aqueous solubilities of ovomucoid and the four fragments were highly dependent on temperature which causes structural alteration due to thermal unfolding of the proteins. The values of KS and beta for domain III and domain II+III at different pHs were similar to those of other globular proteins whereas those of ovomucoid and domain I and domain I+II were atypical. They were explained in terms of the lack of structural stability and the presence of carbohydrate moieties in domains I and II.

Ammonium Sulfate↗
PubMed1992

Colonic immunity in patients and amoebic liver abscess.

Secretory immunoglobulin A (S-IgA), coproantibody titre (antiamoebic) and IgA, IgG, IgM immunocytes in rectal mucosa were studied in 13 patients with amoebic liver abscess (ALA) prior to and 4-6 weeks after completion of antiamoebic therapy. Ten asymptomatic Entamoeba histolytica cyst passers and 17 healthy age and sex matched volunteers served as controls. Fecal S-IgA levels and counts of IgA bearing immunocytes in mucosa were significantly higher in patients with ALA and cyst passers as compared to healthy controls and showed a significant fall after treatment. Fecal antiamoebic antibodies were high in cyst passers and in cases of ALA after treatment. Raised levels of S-IgA and IgA class immunocyte counts probably indicate a local mucosal immune response directed at containing the infection.

Antibodies, Protozoan↗
PubMed1992

Kinetics of specific IgM in patients of hepatic amoebiasis.

Entamoeba histolytica (EH) specific IgM was measured in 54 patients with diagnosed amoebic liver abscess (ALA), 13 with non-suppurative hepatic amoebiasis (NSHA) and 50 controls. The mean levels of EH specific IgM, estimated by ELISA were significantly raised in patients of invasive amoebiasis (both ALA and NSHA) compared to controls (P less than 0.05). EH specific IgG was also raised in both groups of patients. Follow up of patients with ALA showed a significant decline (P less than 0.05) in the specific IgM levels three months after treatment while the specific IgG antibodies persisted in high titres (1:160). Only four patients of NSHA could be followed up and all showed a decline in specific IgM levels. Raised specific serum IgM seems to be an indicator of active (invasive) amoebiasis.

Adult↗
PubMed1992

Auxotyping of Neisseria gonorrhoeae as an additional epidemiological marker.

Auxotypes and penicillin sensitivity of 102 strains of N. gonorrhoeae were studied. Ten distinct auxotypes on the basis of growth requirement to seven amino acids were observed. The commonest pattern seen was zero auxotype (33.3%), followed by auxotype requiring proline (18.6%). MIC of 72 (71.5%) strains ranged from < 0.003 IU/ml to 0.062 IU/ml of benzyl penicillin. MIC of the other 30 (29.5%) strains was found to be > or = 0.125 IU/ml, indicating penicillin resistance. None of the strains were penicillinase producers. A case of reinfection was also detected on the basis of change in auxotype pattern.

Amino Acids↗
PubMed1992

Sucralfate versus ranitidine in non-ulcer dyspepsia: results of a prospective, randomized, open, controlled trial.

In an open trial, 100 patients with non-ulcer dyspepsia were randomized to receive either ranitidine 150 mg twice daily (n = 47) or sucralfate 1 g four times a day (n = 53) for four weeks. An 'intention to treat' analysis revealed that global relief in symptoms was significantly more frequent in the sucralfate group than in the ranitidine group after two weeks (77.4% vs 59.6%; p less than 0.05) and four weeks (86.8% vs 63.8%; p less than 0.001) of treatment. It is concluded that sucralfate is superior to ranitidine in providing symptomatic relief in patients with non-ulcer dyspepsia.

Adult↗
PubMed1979

Gastric acid secretion rate and buffer content of the stomach after a rice- and a wheat-based meal in normal subjects and patients with duodenal ulcer.

The study describes gastric acid secretory response to a rice-based and a wheat-based meal over a prolonged period of five hours and buffer content of the stomach in five normal and seven duodenal ulcer subjects from the rice-eating eastern Indian population. The results suggest that (1) the meal-mediated gastric acid secretory response in duodenal ulcer subjects is much higher than in the controls, even though the histamine stimulated response is similar, (2) the type of meal, whether rice and fish based or wheat and meat based, does not influence the acid secretory response, and (3) the duodenal ulcer subjects in this area, two hours after a meal, have a buffer capacity similar to the controls.

Adult↗