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Biomedical subjects

R Kumar

Publications and source records attributed to R Kumar.

At least 577 records · Page 32Linked to original sources
PubMed1998

Improved biochemical variables, nutrient intake, and hormonal factors in slow nocturnal hemodialysis: a pilot study.

OBJECTIVE: To determine whether slow nocturnal hemodialysis (SNHD) can be safely performed in patients with end-stage renal disease to improve the biochemical and clinical outcome. MATERIAL AND METHODS: We conducted an 8-week pilot study in nondiabetic adult patients, who underwent dialysis 6 nights per week for 8 hours each night. A dialysate flow rate of 300 mL/min and a blood flow rate of 250 mL/min, through an internal jugular dual-lumen venous catheter, were used. The equipment used was a COBE Centry System 3 dialysis machine and Fresenius F-80 (1.8 m2) or Baxter CT 190 (1.9 m2) dialyzers. Five patients were enrolled in the study. RESULTS: Two patients did not complete the study because of catheter-related infections--one at day 7 and one after 4 weeks of SNHD. All patients had improved blood pressure control, and no intradialytic adverse events occurred. Dietary intake improved, urea and creatinine levels significantly decreased, and weekly delivery of dialysate increased on SNHD. Potassium, chloride, beta 2-microglobulin, phosphorus, calcium, and high-density lipoprotein cholesterol all improved on SNHD. Serum testosterone increased in the three men on SNHD, but parathyroid hormone, luteinizing hormone, and follicle-stimulating hormone remained unchanged. Erythropoietin levels increased on SNHD, despite no change in exogenous erythropoietin doses in three patients and discontinuation of administration of erythropoietin in one. The following biochemical factors did not change significantly: serum sodium, bicarbonate, vitamin B12, folate, alkaline phosphatase, total cholesterol, triglycerides, and albumin. CONCLUSION: Higher doses of hemodialysis benefit nutrition, improve biochemical variables, and may improve many hormonal systems.

Adult↗
PubMed1998

The fluorinated quinolones.

Following the discovery of nalidixic acid in 1962, numerous structural modifications have been made to the quinolone nucleus to increase antimicrobial activity and improve pharmacokinetic performance. A major advance occurred during the 1980's with the discovery that a fluorine at position-6 conferred broad and potent antimicrobial activity, (e.g. norfloxacin) but still with relatively less activity for Gram-positive and antiaerobic organisms than Gram-negative bacteria. Subsequent developments produced quinolones with further improvements, predominantly in either solubility (e.g. ofloxacin), antimicrobial activity (e.g. ciprofloxacin) or prolonged serum half-life (e.g. pefloxacin). Recent modifications have attempted to achieve an optimal blend of favourable properties together with minimal potential for undesirable side-effects. The mode of action of quinolones is by blocking of the bacterial enzyme gyrase. This enzyme is responsible for the coiling and supercoiling of the DNA within the cell. When this enzyme is inhibited, DNA transcription, which results in protein synthesis, and DNA replication, which results in cell division, are inhibited. Improvements in antimicrobial activity combined with adequate blood and tissue concentrations do offer expectancy of enhanced therapeutic efficacy for new derivatives in those infections by organisms which are 'marginally' sensitive to currently used quinolones. The possibility of resistance emerging in these organisms during treatment should also be reduced.

Anti-Infective Agents↗
PubMed1998

Quantitative structure-activity relationship study of iodinated analogues of trimetoquinol as highly potent beta 2-adrenoceptor ligands.

Trimetoquinol and its derivatives, reported to be highly potent beta 2-adrenoceptor (beta 2-AR) and site-selective thromboxane A2/prostaglandin H2 (TP) receptor ligands are subjected to quantitative structure-activity relationship (QSAR) study. From the significant correlation equation, obtained between the binding affinity, pKi (beta 2-AR) and the substitutional physicochemical parameters such as molar refraction, (MR), hydrophobic constant, (pi) and resonance parameter, (R), the receptor binding interactions associated with the varying sites of these compounds are discussed. The QSAR study has also explored the possibilities of having the analogous of improved binding affinities in future synthetic efforts. Likewise, the ratio of binding affinities, expressed as-log[Ki(beta 2-AR)/Ki alpha(TP)] related to two receptors are significantly correlated with MR and pi of the substituents and the relationship may, therefore, be helpful in developing the agents of greater selectivity on beta 2-AR versus TP receptor and vice versa.

Adrenergic beta-Agonists↗
PubMed1998

Efficacy of eprinomectin against Hypoderma spp in cattle.

OBJECTIVE: To determine the efficacy of a topical formulation of eprinomectin against natural infestations of first (L1)-stage, and second and third (L2/L3)-stage larvae of Hypoderma spp. ANIMALS: 140 approximately 6- to 18-month-old cattle of various breeds. PROCEDURE: Cattle, selected from herds with high prevalence of Hypoderma infestation, were treated in 4 experiments: within each replicate, 1 animal received eprinomectin at a dosage of 500 micrograms/kg of body weight against first-stage larvae (L1). The second animal received the same treatment against second or third-stage larvae (L2/L3). The third animal served as an untreated control. In a fifth experiment, visible warbles were treated on half of the cattle. Remaining cattle served as vehicle-treated controls. In 1 experiment, warbles were examined from time of treatment until all lesions were resolved. In 4 experiments, emerging Hypoderma larvae were recovered, speciated, and enumerated, and viability was determined. RESULTS: Eprinomectin (500 micrograms/kg) efficacy was complete against L1. Hypoderma L2/L3 eradication approached 100% efficacy (1 live larva was recorded). Warbles in treated cattle resolved in a significantly shorter time than did those in controls. Adverse reactions related to treatment were not observed in any of the trials. CONCLUSIONS: Eprinomectin (500 micrograms/kg) applied topically was safe and highly efficacious for treatment of all larval stages of Hypoderma spp in these trials. CLINICAL RELEVANCE: Attributes of eprinomectin besides antiparasite efficacy allow treatment of all classes of cattle with no need for meat or milk withdrawal.

Administration, Topical↗
PubMed1998

Glaucoma and concomitant status of autonomic nervous system.

There is much clinical evidence to suggest that certain types of Glaucoma are related to activity of autonomic nervous system (ANS). Although some local changes have been documented but systemic association has not been established, so far. Hence, the present study was initiated and an attempt was made to bring out the association of systemic autonomic functions with glaucoma (especially Primary Closed Angle Glaucoma (PCAG)) if any. This study was carried out in the Department of Physiology, Maulana Azad Medical College in association with Glaucoma Clinic of Guru Nanak Eye Centre, New Delhi from June 1993-August 94. ANS function tests were conducted using Polyrite-8-Medicare System. The subjects were confirmed cases of PCAG with 10P-22.1 +/- 4.4 mmHg and possibility of autonomic neuropathy due to any other cause was ruled out. They were matched with normal subjects for their age, anthropometry and were compared for their sympathetic activity of ANS by Galvanic Skin Resistance (GSR); Cold Pressor Response (CPR); corrected QT interval (QTc) and T-wave amplitude (TWA) and for parasympathetic activity of ANS by Resting Heart Rate (RHR); Standing to Lying Ratio (SLR) and Valsalva Ratio and analysed statistically using standard 't' test. The results obtained in this study indicated increase in sympathetic activity in 61% of PCAG subjects and decreased parasympathic activity in 80% of the PCAG subjects when compared with control group of subjects, suggesting association of autonomic neuropathy with PCAG.

Autonomic Nervous System↗
PubMed1998

Multidrug- and metal-resistant strains of Klebsiella pneumoniae isolated from Penaeus monodon of the coastal waters of deltaic Sundarban.

Marine shrimp of the species Penaeus monodon were collected from the coastal region (Haroa) of the deltaic Sundarbans of West Bengal, India during the premonsoon period in 1996. Klebsiella pneumoniae was isolated from the alimentary canal and gills of the shrimp as the sole isolate. All 10 isolated strains were resistant to erythromycin (30 micrograms/mL), ampicillin (100 micrograms/mL), furazolidone (100 micrograms/mL), and penicillin (100 IU). These strains were able to grow in the presence of silver (Ag+), cobalt (Co2+), cadmium (Cd2+), nickel (Ni2+), lead (Pb2+), copper (Cu2+), and zinc (Zn2+) at concentrations up to 10 mM. All the strains showed similar plasmid profiles, ranging in sizes from 1.8 to 120 kb. Resistance to lead, cobalt, nickel, and copper was encoded by a 3.5-kb plasmid of K. pneumoniae. Synthesis of a 14-kDa periplasmic protein was increased when they were grown in presence of 10 mM Cu2+.

Animals↗
PubMed1998

Predictors of outcome in fulminant hepatic failure in children.

OBJECTIVE: To identify the predictors of outcome in fulminant hepatic failure (FHF) in children. STUDY DESIGN: Prospective cohort study. METHODS: 41 children with FHF were studied. Patient characteristics and findings on examination at the time of hospitalization were noted. Serum biochemistry and screening for hepatotropic viruses (A, B and C) were done in each patient. Patients were treated using a predefined protocol and followed up till death or discharge. Univariate and multivariate analysis was done to find the predictors of outcome. RESULTS: Hepatitis B was the commonest cause of FHF (11 children; 26.9%). Markers for hepatitis A and C viruses were present in one and two patients, respectively. Serology was negative in 27 children (65.9%), of whom two had history of ingestion of hepatotoxins (antitubercular drugs). The overall mortality was 61%. Irrespective of etiology, the following factors were associated with poor outcome on univariate analysis: presence of gastrointestinal (GI) hemorrhage, serum bilirubin more than 10 mg/dL, age 6 years or less, coma of grade 3 or more, presence of infection, prolongation of prothrombin time > 8 s over control, prothrombin concentration < 50%, hypoglycemia (blood glucose < 45 mg/dL), hyponatremia (serum sodium < 125 mEq/L) and hyperkalemia (serum potassium > 5.5 mEq/L). On multiple logistic regression analysis, presence of GI hemorrhage (p = 0.005), degree of coma (p = 0.02) and serum bilirubin level (p = 0.025) were identified as independent predictors of mortality.

Child↗
PubMed1998

The role of Gardnerella vaginalis in nonspecific vaginitis in intra uterine contraceptive device users.

Two Hundred Forty patients who had Intra Uterine Contraceptive Device (IUCD) and manifested of nonspecific vaginitis were investigated for the presence of G. vaginalis. Pure growth of this organism was obtained in 14(5.8%) cases while 116(48.3%) cases showed this organism in association with other organisms e.g. Esch. coli (11.7%), Klebsiella (9.2%), Candida (9.2%), Strept. faecalis (7.3%), Proteus species (5.8%) and Staph. albus (5%).

Anti-Bacterial Agents↗
PubMed1998

Pallidotomy and deep brain stimulation of the pallidum and subthalamic nucleus in advanced Parkinson's disease.

There has been a resurgence in the use of neurosurgical procedures for the treatment of Parkinson's disease (PD). Pallidotomy has become a widely performed procedure on the basis of reports which describe marked reduction of levodopa-induced dyskinesias and variable improvement in parkinsonism. Preliminary reports of the effects of globus pallidus internus (GPi) and subthalamic nucleus (STN) deep brain stimulation (DBS) have also been promising. At 6-month follow up, a cohort of our first 40 patients undergoing pallidotomy demonstrated the following mean improvements when examined after drug withdrawal (off) and under optimal medication (on): total motor off scores-31%; total off activities of daily living scores-30%; and total on dyskinesias-63% (contralateral and ipsilateral dyskinesias improved 82% and 50%, respectively). Although improvements in contralateral dyskinesias and total off parkinsonism were sustained at 2-year follow up (N = 11), benefit for ipsilateral dyskinesias was lost after 1-year follow up (N = 24). and postural stability and gait improvements lasted only 3-6 months. On-period, levodopa-resistant symptoms did not benefit from pallidotomy. Mean improvements in 8 patients undergoing GPi DBS (4 unilateral and 4 bilateral) at 3 months were as follows: total motor off scores-27%; total off activities of daily living scores-26%; and total on dyskinesias-60%. At most recent follow up, 6 patients with STN DBS (5 bilateral and 1 unilateral) showed the following mean improvements: total motor off scores-41%; total motor on scores-27%; total off activities of daily living scores-40%; and total on dyskinesias 41%. Pallidotomy reduces dyskinesias and off disability. GPi DBS may have effects similar to pallidotomy, but might be safer when bilateral procedures are required. Bilateral STN DBS may improve off parkinsonism more than other procedures and might also improve on-period motor function. A randomized trial will be required to determine which procedure is most effective for patients with different clinical features.

Adult↗
PubMed1998

Myosin isoforms in uterine smooth muscle during pregnancy in rat.

Effects of uterine stretching and physiological hypertrophy on myosin isozyme were investigated in rat during pregnancy. Both nonpregnant and pregnant rat uteri express a single myosin band on native gels. Analysis of native myosin under denaturing conditions revealed two myosin heavy chains (MHCs) with molecular mass of 204 and 200 kDa respectively. Filamin, a 240 kDa protein co-electrophoreses with myosin on native gels. No correlation is found between regulatory myosin light chain phosphorylation and pattern of myosin isozymes or the MHC. The results suggest that uterine stretching and physiological hypertrophy during pregnancy do not induce any changes in uterine myosin isozyme.

Animals↗
PubMed1998

Prevention of intestinal toxic effects and intensification of irinotecan's therapeutic efficacy against murine colon cancer liver metastases by oral administration of the lipopeptide JBT 3002.

The induction of severe diarrhea limits the usefulness of the DNA topoisomerase I inhibitor irinotecan (CPT-11) in the treatment of advanced colon cancer. We investigated whether oral administration of the new synthetic bacterial lipopeptide, JBT 3002, encapsulated in phospholipid liposomes could prevent damage to the intestinal epithelium and lamina propria and thus allow for the parenteral administration of high-dose irinotecan to mice with established syngeneic CT-26 colon cancer liver metastases. Treatment of mice with four daily i.p. injections of 100 mg/kg irinotecan was effective against liver metastases but also resulted in loss of body weight and early death. Histopathological examination of the intestines after this treatment revealed loss of villi, epithelial vacuolation, decrease in the number of cells in the crypts in S-phase, increase in the number of apoptotic cells, and reduction in the number of lymphocytes in the lamina propria. In contrast, treatment of mice with the same irinotecan regimen after oral administration of JBT 3002 produced highly significant inhibition of liver metastases without detectable damage to the intestines. Studies that used irinotecan administered once a week for 3 weeks after pretreatment with oral JBT 3002 demonstrated significantly intensified eradication of established CT-26 liver metastases compared with treatment with once-weekly irinotecan alone. Histological studies revealed that the liver metastases in mice treated with oral JBT 3002 and i.p. irinotecan contained a higher number of macrophages than metastases in mice treated with either drug alone. In vitro studies revealed that irinotecan produced direct antiproliferative effects but JBT 3002 did not. Tumor cells exposed to both irinotecan and macrophages activated by JBT 3002 were highly susceptible to lysis. These data show that oral administration of JBT 3002 can prevent irinotecan-induced gastrointestinal toxic effects and maintain the integrity of the lamina propria, thus allowing for intensification of irinotecan therapy against liver metastases from colon cancer.

Adjuvants, Immunologic↗