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Biomedical subjects

S Kumar

Publications and source records attributed to S Kumar.

At least 127 records · Page 7Linked to original sources
PubMed1991

N,N-diethylphenylacetamide in treated fabrics as a repellent against Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae).

The efficacy of fabrics impregnated with N,N-diethylphenylacetamide (DEPA), a new repellent, was studied in the laboratory and field against Aedes aegypti (L.) and Culex quinquefasciatus Say. DEPA-treated polyester cotton and cotton fabrics provided repellency for 30 and 36 d and had a half-life of 11 and 5 d, respectively. The repellent could not be applied at a rate of greater than 15% of fabric weight. DEPA-treated fabric patches were found to be a practical and novel approach and were effective for 90 d in the laboratory against Ae. aegypti and 77 d in the field against Cs. quinquefasciatus.

Acetamides↗
PubMed1991

Does breastfeeding influence mortality in children hospitalized with diarrhoea?

The association between breastfeeding and mortality in children hospitalized for diarrhoea was investigated in a prospective manner in 309 subjects below 18 months of age. In multivariate logistic regression analysis, 36 cases who died were compared with 273 controls who were discharged in a satisfactory condition. Breastfeeding had a strong protective effect against mortality even after allowance was made for confounding variables (including nutritional status, chronicity of illness, associated non-enteral infections) and a possible bias of interruption of breastfeeding as an early consequence of the terminal illness. The adjusted odd's ratio (OR) and 95 per cent confidence intervals (95 per cent CI) for the protective effect were 2.7 and 2.1-3.6, respectively. The adjusted OR's (95 per cent CI's) were 6.0 (3.6-10.2), 2.6 (2.0-3.4), and 1.8 (1.4-2.5) for the age intervals 0-6, 7-12, and 13-18 months, respectively (P less than 0.001, less than 0.01, and less than 0.05, respectively). Further stratified analyses suggested a greater benefit in children with severe wasting, severe stunting, protracted illness, and diarrhoea as the sole illness. It is concluded that in children up to 18 months of age, breastfeeding offers substantial protection against death in children hospitalized with diarrhoea.

Breast Feeding↗
PubMed1991

Risk factors for fatal diarrhea in hospitalized children in India.

There is scant information on the risk factors for diarrheal deaths in developing countries. A prospective evaluation was therefore conducted on 382 consecutive children (less than 5 years of age), who were hospitalized with diarrhea. A complete profile, including outcome, was available for 357 patients, 37 of whom died (10.4%). In the univariate analysis, four factors were significantly associated (p less than 0.02) with death: associated major infection (pneumonia, septicemia, or meningitis), severe wasting (less than or equal to 50% weight for age), severe stunting (less than or equal to 85% height for age), and protraction of illness (greater than 14 days). In the multivariate analysis, all four factors retained their significance. The adjusted odds ratios (95% confidence interval) were 4.7 (3.9, 5.6), 3.3 (2.7, 4.0), 1.9 (1.6, 2.3), and 1.5 (1.3, 1.8), respectively. In addition, in children less than 19 months of age (n = 241; 29 deaths) breast-feeding had a significant (p less than 0.001) protective effect (adjusted OR--2.3, 95% CI-1.9-2.8). It is concluded that even in a setting with high diarrheal fatality rates, high-risk children can be identified and targeted for intensive intervention.

Body Height↗
PubMed1991

A case of neonatal tetanus.

The morbidity and mortality from neonatal tetanus are preventable. It is largely a disease of developing countries. This single case of neonatal tetanus in southern Florida must serve as an indicator for the need for health care professionals to evaluate the degree of utilization of maternal health services and the impact of immunization programs for those women at risk, in this case, women who have migrated from developing countries.

Female↗
PubMed1991

The prediction of steady-state plasma phenobarbitone concentrations (following low-dose phenobarbitone) to refine its use as an indicator of compliance.

1. A model for predicting the steady-state plasma concentration of phenobarbitone following low-dose phenobarbitone used as an indicator of compliance was derived using data for 10 healthy volunteers. 2. Each volunteer was given a single 30 mg oral dose of phenobarbitone and the pharmacokinetics were described. Subsequently, volunteers were given phenobarbitone 2 mg daily for 28 days and a further pharmacokinetic profile determined during and after this period. 3. An initial predicted estimate of steady-state plasma drug concentration was made using each volunteer's demographic details. This estimate was revised by Bayesian analysis using single timed samples (24, 48, 72 or 96 h) following the single dose. 4. The model was tested on a further 10 healthy volunteers given a single 8 mg dose and who were subsequently given 2 mg daily for 28 days. 5. The revised estimate of peak steady-state plasma phenobarbitone concentration utilising the 96 h post-single dose concentration (356 ng ml-1) was least biased (mean prediction error +/- 95% CI = 10.6 +/- 19.8 ng ml-1) and most precise (root mean square error +/- 95% CI = 28.3 +/- 19.0 ng ml-1). In all cases the peak or trough steady-state drug concentration was within 13% of the predicted value. 6. The model reflected compliance accurately in a further eight volunteers with simulated partial (two-thirds) compliance. 7. The use of a predictive model using Bayesian analysis to estimate expected steady-state plasma phenobarbitone concentrations could increase further the usefulness of low-dose phenobarbitone as an indicator of compliance.

Adult↗
PubMed1991

Nonlinear effects in the dynamics of clouds of bubbles.

This paper presents a spectral analysis of the response of a fluid containing bubbles to the motions of a wall oscillating normal to itself. First, a Fourier analysis of the Rayleigh-Plesset equation is used to obtain an approximate solution for the nonlinear effects in the oscillation of a single bubble in an infinite fluid. This is used in the approximate solution of the oscillating wall problem, and the resulting expressions are evaluated numerically in order to examine the nonlinear effects. Harmonic generation results from the nonlinearity. It is observed that the bubble natural frequency remains the dominant natural frequency in the volume oscillations of the bubbles near the wall. On the other hand, the pressure perturbations near the wall are dominated by the first and second harmonics present at twice the natural frequency while the pressure perturbation at the natural frequency of the bubble is inhibited. The response at the forcing frequency and its harmonics is explored along with the variation with amplitude of wall oscillation, void fraction, and viscous and surface tension effects. Splitting and cancellation of frequencies of maximum and minimum response due to enhanced nonlinear effects are also observed.

Acoustics↗
PubMed1991

Protective role of bovine neutrophils in Pasteurella haemolytica-mediated endothelial cell damage.

The purpose of this study was to determine if Pasteurella haemolytica can directly injure bovine pulmonary endothelial cells (EC) and if neutrophils have a beneficial or detrimental role in bacterium-EC interaction. Various combinations of live P. haemolytica, heat-killed P. haemolytica, anti-P. haemolytica immune serum, polymyxin B, and bovine neutrophils were added to confluent monolayers of bovine EC. Monitoring included determination of 51Cr release from EC, phase microscopy, and transmission electron microscopy. Although toxic changes were not evident at 5 h postinoculation, both live and heat-killed P. haemolytica produced extensive EC damage by 22 h postinoculation. Damage by live P. haemolytica was prevented only when both neutrophils and immune serum were used. Polymyxin B effectively prevented the toxic effect of heat-killed P. haemolytica, suggesting that lipopolysaccharide was the major toxic factor. Morphological studies showed close apposition of P. haemolytica to EC membranes, neutrophil activation, and adherence to EC but no evidence of neutrophil-associated EC membrane damage. These studies demonstrate that neutrophils and immune serum in combination are effective in preventing EC damage mediated by live P. haemolytica.

Animals↗
PubMed1991

Na:K pump abundance and function in MDCK cells: effect of low ambient potassium.

Side-specific expression and activity of Na:K pump was studied in Madin-Darby canine kidney (MDCK) cells, a tissue culture model of distal renal tubular epithelium, exposed to low ambient potassium. Confluent monolayers grown on teflon filters in dual chambers were treated with a low K+ medium from 45 min to 72 h. After both acute (45 min) and longer-term (24-72 h) exposure to low K+ (0.7 mM), cation cycling rate of existing pump units increased substantially, while there was no significant change in total cell Na-K-ATPase activity or in basolateral surface pump density. Although a small quantity of Na:K pumps (less than 10%) was consistently present apically, it also did not increase after exposure to low K+, or when the monolayers were provided K+ only from the apical side. In MDCK monolayers low K+ enhances the rate of K+ uptake by the existing pump units but does not increase the total number of pumps or their deployment on either cell surface.

Animals↗
PubMed1991

Obstruction of the infrarenal portion of the abdominal aorta: results of treatment with balloon angioplasty.

Our experience in the treatment of stenoses of the infrarenal portion of the abdominal aorta with balloon angioplasty in 27 patients is reported. Clinical findings were lower limb claudication (all patients), impotence (eight patients), and blue-toe syndrome (two patients). The underlying disease was atherosclerosis in 24 patients and nonspecific aortoarteritis in three patients. Dilatation was successful in all patients. Embolic occlusions of the left common iliac artery (one patient) and left superficial femoral artery (one patient) were the only major complications. Claudication in the affected limb continued in the first patient; the second died when diagnostic angiography, performed 3 months after angioplasty, caused a severe atheroembolus. Of the other 25 patients, nine of the 10 followed up for 13-48 months and all seven followed up for 3-8 months were free of symptoms. Six of eight patients with sexual dysfunction had normal function after angioplasty. Seven patients still awaited follow-up and one was lost to follow-up. Our experience suggests that balloon angioplasty is an effective treatment of stenoses of the infrarenal portion of the abdominal aorta.

Adult↗
PubMed1991

Comparison of latex agglutination and polyacrylamide gel electrophoresis with enzyme linked immunosorbent assay for detecting human rotavirus in stool specimens.

One hundred and forty five stool samples from children below 2 years of age, hospitalized with diarrhea were tested for rotavirus antigen by enzyme linked immunosorbent assay (ELISA), latex agglutination test using commercially available kit Rotastat (Ranbaxy Diagnostic, India) and by polyacrylamide gel electrophoresis. Twenty eight samples were positive for the virus antigen by all the three assay systems. The sensitivity of latex agglutination (LA) and polyacrylamide gel electrophoresis (PAGE) was 91.4% (32/35) and 80% (28/35), respectively; the corresponding specificity was 98.18% (108/110) and 100% (110/110), respectively. Latex agglutination was the least complex, required the least amount of apparatus and provided a result within a short time. It showed a high specificity and a reasonable amount of sensitivity and the results correlated well with ELISA and PAGE.

Antigens, Viral↗
PubMed1991

Involvement of mono-oxygenases as a major mechanism of deltamethrin-resistance in larvae of three species of mosquitoes.

Role of mono-oxygenases as a mechanism of resistance to the synthetic pyrethroid, deltamethrin in the larvae of Culex quinquefasciatus Say, Aedes aegypti L. and Anopheles stephensi Liston developed by laboratory selections with deltamethrin, DDT or deltamethrin and the synergist, piperonyl butoxide (PBO) in the ratio of 1:5, was investigated. There was a significant correlation with mono-oxygenase activity and larval LC50 to deltamethrin in various strains of all the three species. In addition, the activity of glucose-6-phosphate dehydrogenase (G6PD), the main NADPH generating enzyme for mono-oxygenases, also showed enhanced activity in deltamethrin and DDT-selected strains. The present data, therefore, clearly suggest that deltamethrin resistance in the larvae of Cx. quinquefasciatus, Ae. aegypti and An. stephensi is mainly due to the detoxification of deltamethrin by microsomal mono-oxygenases. High activity of G6PD observed in DDT-selected strains seems to be related to its role as a rate-limiting enzyme in GSH-dependent dehydrochlorination of DDT.

Aedes↗
PubMed1991

T and B lymphocytes in patients with enteric fever.

Estimation of T and B lymphocytes was done in 50 patients of enteric fever, 50 duration matched non enteric fever patients and 50 normal healthy individuals. The difference in both early and late rosette forming T lymphocytes was found to be statistically significant in enteric versus non-enteric patients. Significant difference was also observed in enteric versus normal individuals in case of late rosette forming T lymphocytes.

Adolescent↗
PubMed1991

Effect of Pasteurella haemolytica saline capsular extract on bovine pulmonary endothelial cells.

The purpose of this in vitro study was to determine whether Pasteurella haemolytica capsular extract (CE) damages bovine pulmonary endothelial cells (EC) directly or through neutrophil-mediated mechanisms. Chromium 51-labeled EC were treated with the following variables: CE (1, 10, and 100 ng of protein/ml), CE and bovine neutrophils (10(6) cells/well), and CE and polymyxin B (500 U/ml). Although only minimal damage to EC occurred by 5 hours after treatment, by 22 hours after treatment, the 10-ng and 100-ng CE dose produced severe damage to EC, as indicated by 51Cr release, cellular detachment, and loss of monolayer confluency. The component in the CE that was toxic to the EC was lipopolysaccharide, evidenced by effective neutralization of the toxic effect with polymyxin B. Neutrophils inhibited the CE-mediated EC toxicity and were activated, as indicated by shape change and adhesion to EC monolayers. We concluded that the lipopolysaccharide component of CE causes direct damage to EC, which can be attenuated by neutrophils and polymyxin B.

Animals↗