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Biomedical subjects

N Chandra

Publications and source records attributed to N Chandra.

At least 73 records · Page 4Linked to original sources
PubMed1980

Simultaneous chest compression and ventilation at high airway pressure during cardiopulmonary resuscitation.

In most patients blood flow during cardiopulmonary resuscitation (CPR) results from a rise in intrathoracic pressure rather than from direct heart compression. Intrathoracic pressure was increased by the use of positive-pressure ventilation synchronous with sternal compression in eleven arrested patients who were intubated. A computer system allowed 15-30 s periods of alternation between conventional CPR and "new CPR" (rate of 40/min, 60% compression duration, and simultaneous ventilation at airway pressures from 60 to 110 cm H2O). Compression force was identical with the two methods. New CPR increased mean systolic radial artery pressure significantly from 40.6 +/- 4.4 to 53.1 +/- 3.9 mm Hg for 14 runs in nine patients. In 15 runs in ten patients an index of carotid flow increased with new CPR to 252% (range 113-643%) of control values. Lowering airway pressure during a new CPR lowered flow index and arterial pressure, confirming that these increases with new CPR were due to higher intrathoracic pressure. Thus, increased airway pressure synchronous with sternal compression increases arterial pressure and likely blood flow during CPR in man. However, further studies of potential complications and long-term effects of new CPR, particularly on adequacy of ventilation, are needed before clinical implementation is undertaken.

Blood Circulation↗
PubMed1967

Studies of the chemical composition of a healing skin wound in rats, and of the concentrations of some constituents of tissues distant from the healing wound.

1. A skin lesion was made in rats by dorsal incision and the insertion of a polythene tube. 2. Over a period of 25 days after wounding, assays were performed for ascorbic acid, DNA, hydroxyproline, methionine, tryptophan, tyrosine and free amino acids in the lesion tissue. 3. The neutral-salt-soluble proteins of the lesion tissue were fractionated on DEAE-Sephadex, with the separation of fibrinogen and gamma-globulin from a serum protein fraction. 4. Over a period of 20 days after wounding, in wounded rats and in controls, assays were conducted for: ascorbic acid in lens and liver, hydroxyproline, soluble protein, methionine and water in muscle and tendon, and free amino acids in muscle. 5. Relative to controls there was a decrease in lens and liver ascorbic acid, a rise in tendon hydroxyproline, a rise in muscle free amino acids, a fall in muscle protein and a rise in tendon and muscle water.

Journal Article↗
PubMedDate not supplied

Substructure-based support vector machine classifiers for prediction of adverse effects in diverse classes of drugs.

Unforeseen adverse effects exhibited by drugs contribute heavily to late-phase failure and even withdrawal of marketed drugs. Torsade de pointes (TdP) is one such important adverse effect, which causes cardiac arrhythmia and, in some cases, sudden death, making it crucial for potential drugs to be screened for torsadogenicity. The need to tap the power of computational approaches for the prediction of adverse effects such as TdP is increasingly becoming evident. The availability of screening data including those in organized databases greatly facilitates exploration of newer computational approaches. In this paper, we report the development of a prediction method based on a support machine vector algorithm. The method uses a combination of descriptors, encoding both the type of toxicophore as well as the position of the toxicophore in the drug molecule, thus considering both the pharmacophore and the three-dimensional shape information of the molecule. For delineating toxicophores, a novel pattern-recognition method that utilizes substructures within a molecule has been developed. The results obtained using the hybrid approach have been compared with those available in the literature for the same data set. An improvement in prediction accuracy is clearly seen, with the accuracy reaching up to 97% in predicting compounds that can cause TdP and 90% for predicting compounds that do not cause TdP. The generic nature of the method has been demonstrated with four data sets available for carcinogenicity, where prediction accuracies were significantly higher, with a best receiver operating characteristics (ROC) value of 0.81 as against a best ROC value of 0.7 reported in the literature for the same data set. Thus, the method holds promise for wide applicability in toxicity prediction.

Algorithms↗
PubMedDate not supplied

Use of captopril as an isolated agent for the management of stable angina pectoris--a double blind randomised trial.

In this double blind randomised placebo controlled study, we investigated the antianginal efficacy of oral captopril in 33 patients of angiographically documented coronary artery disease (chronic stable angina). Apart from sublingual nitrates, all other antianginal drugs were withdrawn. Patients were then evaluated both subjectively by questionnaire and objectively by treadmill stress test. No patient had more than mild hypertension and all patients had good left ventricular function. One group of patients received oral captopril while the other group was given placebo. A repeat assessment was done after six weeks and the results compared with baseline. Anginal attacks decreased from 20.11 +/- 1.86 per week on placebo to 9.92 +/- 1.38 (p < 0.01) on captopril as also the number of sublingual nitrates (18.84 +/- 3.01 to 11.14 +/- 2.94, p < 0.01). Assessment by the treadmill stress test showed that in comparison to the pretreatment test, captopril therapy resulted in a significantly increased exercise duration (6.26 +/- 0.21 to 6.98 +/- 0.31 minutes, p < 0.05), total work done (6.76 +/- 0.26 METS to 7.48 +/- 0.29 METS, p < 0.05). In addition there was a significant increase in time to angina (6.16 +/- 0.18 to 6.85 +/- 0.24 min, p < 0.05) and time to 1mm ST depression (5.18 +/- 0.26 to 6.46 +/- 0.30 min, p < 0.01). We conclude that captopril is an effective monotherapy for patients with chronic stable angina and has both antianginal as well as anti-ischemic effects, possibly secondary to direct coronary vasodilation.

Aged↗
PubMedDate not supplied

The efflux of nor-epinephrine from platelets in genetic hypertension.

Platelets have been used as a model of sympathetic neurons to study the storage of nor-adrenaline in normotensive individuals belonging to families with essential hypertension for at least two generations. The efflux and initial efflux rate (K) of noradrenaline was determined in 36 young relatives (mean age 29.2 years) and in 20 young controls with no family history of hypertension (mean age 26.5 years). From the groups of relatives all those with definite hypertension had been excluded. Efflux and efflux rate K was significantly higher in young relatives (50.82 +/- 3.84 and 28.2 +/- 6.3) than in the controls (39.2 +/- 0.71 and 15.2 +/- 4.8). Of the relatives 25.2% had higher K values than any of the controls.

Adolescent↗
PubMedDate not supplied

Clinical relevance of vegetations in infective endocarditis.

Two-dimensional echocardiograms of 58 patients with infective endocarditis were examined to determine if presence and/or size of vegetations on echocardiogram were predictive of morbidity and mortality. Group 1 (38 patients) with one or more vegetations, had a significantly higher rate of complications (emboli, congestive heart failure, need for surgery and death) than group 2 (20 patients) without vegetations (p less than 0.001). Analysis of morphologic characteristics of the vegetations in group 1 was of no predictive value for complications in individual patients. In contrast, patients whose echocardiograms demonstrated vegetations on aortic valve had a significantly higher incidence of heart failure, embolisation, surgery and death than those with vegetations on mitral valve. Thus, the detection of vegetations on initial echocardiogram clearly identifies a subgroup at risk for complications, more so if vegetations are present on the aortic valve, but the vegetations size does not predict an adverse clinical outcome.

Adult↗
PubMedDate not supplied

The efflux of nor-epinephrine from platelets in essential hypertension.

The precise role of sympathetic nervous system in initiation and/or maintenance of essential hypertension is unclear even today. Platelets have been used as a suitable model for studying neuronal turnover of biogenic amines. The present study comprised of hypertensive subjects (23) and normotensive controls (10). Hypertensive subjects exhibited significantly enhanced norepinephrine efflux from platelets at both 30 minutes and 60 minutes (p less than 0.001). The percent norepinephrine efflux from platelets correlated with diastolic (r = 0.66 and 0.76) and mean arterial blood pressure (r = 0.54 and 0.65) but not with systolic blood pressure. The norepinephrine efflux rate (K) similarly correlated with diastolic and mean arterial blood pressure in hypertensive subjects studied. From the above findings it appears that operative sympathetic nervous system activity is enhanced in essential hypertension. The enhanced efflux of norepinephrine from platelets may also indicate activated state of platelets in hypertension. Both could be important in genesis and complications of essential hypertension.

Adult↗
PubMedDate not supplied

Abdominal binding during cardiopulmonary resuscitation in man.

Prior studies in dogs have shown improved blood pressure (BP) and carotid flow with abdominal binding during cardiopulmonary resuscitation (CPR). We assessed the effect of abdominal binding at pressures of 60 to 110 cm H2O during CPR in ten patients experiencing cardiac arrest. Abdominal binding for brief periods (30 to 60 s) raised mean arterial pressure from 53.9 +/- 7.1 mm Hg before binding to 67.2 +/- 8.4 mm Hg after binding. In six patients studied who had abdominal binding performed for four minutes, this beneficial effect was still apparent at the end of the time period. No abdominal visceral injury was found in six patients at autopsy. Thus, abdominal binding is an effective yet simple technique for increasing BP during CPR in man with considerable field use potential.

Abdomen↗
PubMedDate not supplied

Beneficial effects of long-term metoprolol therapy on cardiac haemodynamics in patients with mitral stenosis in sinus rhythm--a randomised clinical trial.

We conducted a placebo controlled randomised clinical trial to evaluate the effects of 6 months therapy with metoprolol on resting and exercise haemodynamics in 31 patients with isolated mitral stenosis in sinus rhythm. Twenty six of them (placebo n = 13, metoprolol n = 13) completed the study protocol. Their mean age was 23.1 +/- 7.9 years and the mean mitral valve area was 0.93 +/- 0.25 cm2. The dose of metoprolol ranged between 50-100 mg per day. The primary outcome variables for the study were the resting and exercise mean pulmonary capillary wedge pressure (PCWP) and cardiac index (CI) and the secondary outcome variables consisted of resting and exercise heart rate, mean pulmonary artery pressure (PAP), mean pulmonary vascular resistance (PVR) and clinical improvement on visual analog scale. These outcome variables were assessed blindly. The resting and exercise mean PCWP (mmHg) increased by 9.1 +/- 3.1 and 16.4 +/- 6.4 on placebo and 2.5 +/- 2.1 and -4.6 +/- 2.3 on metoprolol after 6 months therapy. These differences were statistically significant (p < 0.01). The resting and exercise CI (liters/min/m2) decreased by 0.2 +/- 0.1 and 0.1 +/- 0.1 on placebo and 0.3 +/- 0.5 and 0.3 +/- 1.0 on metoprolol. These haemodynamic effects were accompanied with much better symptomatic improvement in patients treated with metoprolol. The differences in change in mean PAP and PVR in two groups were statistically not significant. Our results suggest that the symptomatic patients with MS, waiting for definitive intervention for 6 months or less, would benefit if given beta blockers during this period.

Adult↗