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Biomedical subjects

S Venkataraman

Publications and source records attributed to S Venkataraman.

At least 37 records · Page 2Linked to original sources
PubMed1998

Use of the esophageal detector device in a newborn-piglet model.

STUDY OBJECTIVE: To determine the accuracy of the esophageal detector device (EDD) in predicting correct endotracheal tube (ETT) placement in a newborn-piglet model. METHODS: We used an EDD, comprising a 5-, 10- or 20-mL syringe attached to 4-mm tubing fitted to a 15-mm ETT adapter, to aspirate gas from cuffed or uncuffed ETTs placed in the trachea or esophagus of each newborn piglet. During aspiration, we noted any resistance encountered while pulling back the plunger of the syringe and recorded the total volume of gas aspirated into the syringe. A positive test, signifying tracheal ETT placement, was defined as the ability to freely aspirate gas without resistance and the aspiration of enough gas to fill the entire volume of the syringe. A negative test, signifying esophageal ETT placement, was defined as resistance encountered during the aspiration of gas into the syringe and rebound of the syringe plunger, leading to aspiration of a volume of gas less than the total volume of the syringe. RESULTS: We conducted 444 trials (222 for uncuffed ETTs, 222 for cuffed ETTs). ETT size ranged from 3.0 to 4.5 mm. For cuffed ETTs, the 5-mL syringe had a sensitivity of 100% and a specificity of 5%, the 10-mL syringe had a sensitivity of 95% and a specificity of 16%, and the 20-mL syringe had a sensitivity of 86% and a specificity of 97%. For uncuffed ETTs, the 5-mL syringe had a sensitivity of 100% and a specificity of 5%, the 10-mL syringe had a sensitivity of 97% and a specificity of 24%, and the 20-mL syringe had a sensitivity of 81% and a specificity of 100%. CONCLUSION: No syringe had 100% sensitivity and specificity in correctly predicting ETT placement. The 20-mL syringe had the highest combination of sensitivity and specificity. Further studies are warranted to determine whether the EDD using a 20-mL syringe would aid in the prediction of correct ETT placement in the pediatric population.

Animals↗
PubMed1997

Predicting conserved water-mediated and polar ligand interactions in proteins using a K-nearest-neighbors genetic algorithm.

Water-mediated ligand interactions are essential to biological processes, from product displacement in thymidylate synthase to DNA recognition by Trp repressor, yet the structural chemistry influencing whether bound water is displaced or participates in ligand binding is not well characterized. Consolv, employing a hybrid k-nearest-neighbors classifier/genetic algorithm, predicts bound water molecules conserved between free and ligand-bound protein structures by examining the environment of each water molecule in the free structure. Four environmental features are used: the water molecule's crystallographic temperature factor, the number of hydrogen bonds between the water molecule and protein, and the density and hydrophilicity of neighboring protein atoms. After training on 13 non-homologous proteins, Consolv predicted the conservation of active-site water molecules upon ligand binding with 75% accuracy (Matthews coefficient Cm = 0.41) for seven new proteins. Mispredictions typically involved water molecules predicted to be conserved that were displaced by a polar ligand atom, indicating that Consolv correctly assesses polar binding sites; 90% accuracy (Cm = 0.78) was achieved for predicting conserved active-site water or polar ligand atom binding. Consolv thus provides an accurate means for optimizing ligand design by identifying sites favored to be occupied by either a mediating water molecule or a polar ligand atom, as well as water molecules likely to be displaced by the ligand. Accuracy for predicting first-shell water conservation between independently determined structures was 61% (Cm=0.23). The ability to predict water-mediated and polar interactions from the free protein structure indicates the surprising extent to which the conservation or displacement of active-site bound water is independent of the ligand, and shows that the protein micro-environment of each water molecule is the dominant influence.

Algorithms↗
PubMed1997

Recovery from doxacurium infusion administered to produce immobility for more than four days in pediatric patients in the intensive care unit.

Doxacurium was administered by titrated infusion to 14 pediatric patients for 4.7-12.3 days after laryngotracheal reconstruction to produce minimum spontaneous movement and less than five posttetanic movements of the first toe after stimulation of the posterior tibial nerve. Recovery was documented by stimulation of the ulnar nerve with 2 Hz for 2 s (train-of-four [TOF]) at intervals of 1 min and measurement of the ratio of the fourth to the first response (TOF ratio) at the adductor pollicis. During spontaneous recovery, the TOF ratio was between 0.4 and 0.7 for 0.6-3.3 h, mean (SEM) 2.2 (0.31) h. The TOF ratio equaled 1 between 4.7 and 23.0 h, mean (SEM) 11.0 (2.1) h after termination of doxacurium infusion. In six of the patients, weakness and decreased coordination were noted for a few days to weeks postoperatively. There were no complications related to impairment of upper airway function or ventilation in those patients who had recovery of neuromuscular transmission to the extent of TOF ratio equal to 1 prior to extubation or in those patients in whom weakness or lack of coordination was noted after tracheal extubation.

Child↗
PubMed1996

Trends of smoking among medical students.

The overall smoking prevalence among male medical students between the years 1955 and 1988 in a medical college in South India was 39.51 per cent. The trends of smoking appeared to be in three phases. An initial phase comprising of a steady rise to a peak in the late sixties and seventies, followed by a plateau of the prevalence in the next ten years and ultimately a sharp fall in the last five years. Study based on a mailed-in questionnaire to ten batches of students selected randomly, to study the factors affecting initiation and quitting of smoking showed that the peak period of initiation seemed to be in the two years before and after joining the course. There was a significant relationship between the presence of a smoker in the family and picking up the habit. Conversely, no significant relationships were found with respect to quitting.

Education, Medical↗
PubMed1994

A study on the therapeutic efficacy of Cassia alata, Linn. leaf extract against Pityriasis versicolor.

The therapeutic efficacy of Cassia alata leaf extract against Pityriasis versicolor has been reported for the first time involving humans. For the collection of clinically effective antifungal compounds from the leaves of Cassia alata, a simple procedure has been devised. A 10-year human study indicates that the leaf extract can be reliably used as a herbal medicine to treat Pityriasis versicolor. The leaf extract has no side-effects.

Adolescent↗
PubMed1994

Albendazole therapy for neurocysticercosis.

Based on clinical evaluation and computed tomography (CT) of the brain, 30 cases of neurocysticercosis were diagnosed. Diagnosis was supported by presence of histopathologically proven subcutaneous cysticerci in 12 cases. Three primary neurological syndromes were established i.e. epilepsy in 22 cases, increased intracranial tension in 6 cases and meningoencephalitis in 2 cases. Albendazole was administered orally in a dose of 15 mg/kg bodyweight/day for 30 days without prophylactic steroids. Follow up CT study at 3 months and 12 months revealed complete regression of all lesions in 2 cases, partial regressions in 14 cases and change in morphology in 4 cases. Transient appearence of fresh subcutaneous cysticerci as a side effect of therapy was noted in 4 cases. Albendazole, though acting slow, is considered a suitable alternative to praziquantel in medical management of parenchymal neurocysticercosis.

Adolescent↗
PubMed1993

Gliclazide in the treatment of obese non-insulin dependent diabetic patients.

The clinical efficacy of gliclazide and its effect on plasma glucose, body weight and serum lipids was assessed in a 3 months open trial of 30 obese, Non-Insulin Dependent diabetes mellitus (NIDDM) patients who failed to respond to diet therapy alone. By day 20, the mean post prandial plasma glucose (PPG), and fasting plasma glucose (FPG) were significantly reduced from 276 +/- 13.5 to 195.8 +/- 13.9 mg % (p < 0.01) and 179 +/- 9.3 to 130.6 +/- 9.6 mg % (p < 0.01) respectively. This early glycaemic control was maintained, and by 3 months a further significant decrease occurred in PPG to 156.46 +/- 7.6 mg % (p < 0.01), and FPG to 106.9 +/- 3.8 mg % (p < 0.01). Mean glycosylated haemoglobin (HbA1c) was reduced from 10.3% to 7.7%. The drug had a favourable effect on serum lipids, significantly increasing high density lipoprotein fraction of cholesterol (HDL-C) (p < 0.034), and decreasing low density lipoprotein fraction of cholesterol (LDL-C) (p < 0.049). Mean body weight showed a significant reduction of 1.5 kg (p < 0.003). We conclude that gliclazide is an effective hypoglycaemic agent that ensures a rapid and sustained blood glucose control with a favourable effect on lipids and body weight in obese NIDDM patients.

Blood Glucose↗
PubMed1992

Mania associated with fluoxetine treatment in adolescents.

Fluoxetine, a selective serotonin reuptake inhibitor, is gaining increased acceptance in the treatment of adolescent depression. Generally safe and well tolerated by adults, fluoxetine has been reported to induce mania. The cases of five depressed adolescents, 14-16 years of age, who developed mania during pharmacotherapy with fluoxetine, are reported here. Apparent risk factors for the development of mania or hypomania during fluoxetine pharmacotherapy in this population were the combination of attention-deficit hyperactivity disorder and affective instability; major depression with psychotic features; a family history of affective disorder, especially bipolar disorder; and a diagnosis of bipolar disorder. Further study is needed to determine the optimal dosage and to identify risk factors that increase individual vulnerability to fluoxetine induced mania in adolescents.

Adolescent↗
PubMed1992

Effect of bed time intermediate acting insulin in NIDDM subjects refractory to a combination of sulphonylureas and biguanides.

The effect of a single dose of intermediate acting (Lente) insulin given subcutaneously at 9.00 P.M. in 22 NIDDM subjects refractory to a combination of Sulphonylureas and Biguanides was analysed. Euglycemia was achieved and maintained during the study period of three months with a mean insulin requirement of 14.22 +/- 5.98 units/day. Plasma FFA, Total cholesterol, triglyceride and VLDL-cholesterol also showed significant reduction. The level of FFA modulates hepatic glucose production, which in turn correlates positively with the fasting blood glucose. The therapeutic modality of bed time Lente Insulin based on physiological principles is an effective way of achieving glycemic control in NIDDM subjects who have become non-responsive to oral hypoglycemic agents.

Biguanides↗
PubMed1992

Peripartum cerebral venous thrombosis.

The clinical and computed tomography (CT) features of 25 patients with peripartum CVT are described. Majority of the patients presented in postpartum period and did not receive proper antenatal care. Headache (92%), altered sensorium (80%, seizures (76%), papilloedema (80%) and hemiplegia (52%) were the common modes of presentation. CT findings included diffuse brain oedema (52%), haemorrhagic or nonhaemorrhagic infarctions on one or both sides of brain (48%), gyral enhancement (40%) and tentorial enhancement (16%). While 15 patients made good recovery, 3 cases (12%) died during acute stage of illness.

Adult↗
PubMed1991

Inhibition of human collagenases by sulfur-based substrate analogs.

A series of sulfhydryl and novel sulfur-based substrate-analog inhibitors has been synthesized and tested against human fibroblast and neutrophil collagenases. Absolute stereospecific synthesis of several sulfhydryl inhibitors establishes that it is the diastereomers with the R-configuration of the P'1 residues, which correspond to the unnatural D-amino acid analogs, that are the most potent inhibitors. The corresponding disulfide, sulfonate, sulfinate, sulfide, sulfoxide and sulfone analogs exhibit widely variable levels of potency, but all less than the sulfhydryl compounds. No correlation between inhibitor potency and any single structural feature of these new compounds is apparent. However, differences in potency can be ascribed to the different affinities of these functional groups for zinc coordination and hydrogen bonding to nearby active site residues.

Amino Acid Sequence↗
PubMed1991

Fast feedback regulation of ACTH by cortisol.

1. Fast feedback regulation of ACTH by cortisol has not been well studied in humans. The authors studied the existence and characteristics of fast feedback regulation in normal humans. 2. Hydrocortisone hemisuccinate was infused at two different rates: 6 mg/hour and 12 mg/hour for two hours. 3. The studies did not demonstrate the existence of fast feedback regulation of basal ACTH concentration by cortisol in man. Further, the response was variable and the rate sensitive character was difficult to demonstrate.

Adrenocorticotropic Hormone↗
PubMed1991

Clinical spectrum of myasthenia gravis and problems of management.

Seventeen cases of myasthenia gravis, aged 20-79 years, including one case of ocular myasthenia gravis, seen over a 3 year period, were analysed. Dysphagia was the presenting symptom in two cases. One patient had ectopic thymus gland in relation to the cardiac border, which posed difficulty in diagnosis. A majority of the patients were on medical treatment, including neostigmine, prednisolone and azathioprim. Plasmapheresis was done in 4 cases during crisis, with significant benefit. One patient was put on intermittent ventilatory support for 14-16 hours a day for over 2 years; she died during a power failure. Seven patients were subjected to thymectomy.

Adult↗