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Biomedical subjects

S Radhakrishnan

Publications and source records attributed to S Radhakrishnan.

At least 19 recordsLinked to original sources
PubMed1997

Takayasu's arteritis: evaluation with three-dimensional time-of-flight MR angiography.

Three-dimensional time-of-flight MR angiography was performed in 16 patients with Takayasu's arteritis. Two regions were evaluated, the arch of aorta and its intrathoracic major branches, and the abdominal aorta with proximal portions of its major visceral and renal branches. Individual arteries and aortic segments, i. e. aortic arch and abdominal aorta, were evaluated for abnormalities such as stenosis, occlusion, dilatation and aneurysm formation. The results were compared with contrast angiography. Follow-up MR angiography was performed in three patients after 9-12 months. MR angiography demonstrated steno-occlusive lesions in all the patients and aneurysms in 2. In comparison with contrast angiography, good correlation was found in 129 of the 145 arteries and aortic segments. For the 12 false-positive results, incorrect slab placement and overestimation of stenosis were implicated. Interestingly, there were three false-negative results and one occlusion was underestimated as stenosis. A new lesion developed in 1 patient and one stenosis progressed in another patient upon follow-up. Three-dimensional time-of-flight MR angiography is a simple and fairly accurate method for documenting the lesions in Takayasu's arteritis and for its follow-up.

Adolescent↗
PubMed1997

Ulcerative colitis in Oman. A prospective study of the incidence and disease pattern from 1987 to 1994.

OBJECTIVE: Inflammatory bowel disease has been reported to have varying frequencies in different parts of the world, and there seem to be significant differences in the disease pattern and clinical course in cases of ulcerative colitis (UC). The aim of the present study was to assess the incidence and disease pattern of UC in Oman. METHOD: A prospective study, over a period of 8 years (1987-1994), was performed to study 108 patients found to have UC. RESULTS: The annual incidence of UC was 1.35/100,000. The disease was mainly seen in the middle and upper middle class group, and the majority were nonsmokers or exsmokers. There was no significant difference in the incidence of the disease between nationalities or sexes. Total colitis was seen in 18%, and a significant number had disease extending up to the splenic flexure. Proctitis was seen in 8%. Although, the extent of the disease was similar to reports from the West, these patients had fewer hospital admissions, blood transfusions and none of them suffered local complications such as toxic dilatation, perforation or severe bleeding. Sclerosing cholangitis occurred in 2 patients. Patients were followed up for a maximum period of up to 7 years after diagnosis and none developed dysplasia or cancer. Three patients had surgery mainly for failure of medical treatment. CONCLUSIONS: From this report it seems that UC occurs in Oman at a lower frequency compared to the West. Although, the extent of the disease was similar to Europeans, these patients had less severe disease with fewer complications.

Adolescent↗
PubMed1997

Absent conal septum in tetralogy of Fallot. An angiographic study.

Absent conal septum in tetralogy of Fallot (TF) is usually noted intraoperatively when the ventricular septal defect (VSD) is found abutting the pulmonary valve, its superior rim being nearly inaccessible transatrially, and the posterior rim being separated from the tricuspid valve (TV) by a muscular ridge. The authors retrospectively analyzed angiograms of 208 consecutive patients with TF seen at their center from July 1989 to December 1995 for absence of the conal septum and the presence of an interval between the TV and the margin of the VSD in 30 degrees right anterior oblique view. In 13 (6%) patients, angiograms were inadequate or of poor quality for assessment and were excluded. Twenty-two of the remaining 195 (11%) patients had a large muscular interval between the tricuspid annulus and the margin of the VSD, which was associated with an absent conal septum in 14 (7.2%) and a diminutive septum in 8 (4%) patients. Nine of the 14 patients with an absent conal septum at angiography underwent surgery, and this finding was confirmed in all. The authors conclude that absent conal septum is not uncommon in TF and constitutes an important variation in its anatomy that can be identified preoperatively at angiography for optimal surgical management.

Coronary Angiography↗
PubMed1997

Immediate and follow up results of Inoue balloon mitral valvotomy in juvenile rheumatic mitral stenosis.

BACKGROUND AND AIMS OF THE STUDY: Juvenile rheumatic mitral stenosis (MS) with severe pulmonary venous and arterial hypertension (PAH) is a relatively common occurrence in developing countries. The study objectives were to evaluate the safety, efficacy and follow up of Inoue balloon mitral valvotomy (IBMV) in juveniles with rheumatic MS. METHODS: A total of 193 patients with juvenile rheumatic MS were analyzed and compared with adults, with specific reference to the effect of IBMV on hemodynamics and pulmonary vasculature in patients with severe PAH. RESULTS: Mitral valve areas were smaller (0.76 +/- 0.22 versus 0.81 +/- 0.22 cm2), while mean pulmonary arterial pressure (MPAP) (44.5 +/- 16.5 versus 38.4 +/- 15.1 mmHg) and pulmonary vascular resistance (PVR) (5.5 +/- 4.6 versus 4.41 +/- 4.04 Wood units) were greater in juvenile patients when compared with adults. There was a 99% procedural success. Juvenile patients showed an overall greater fall in MPAP and PVR when compared with adults. The incidence of severe PAH was much higher (32%) among juveniles than adults (16%). Only 5% of patients with juvenile MS with severe PAH had residual severe PAH immediately after IBMV, compared with 17% in older patients. Hemodynamic benefits (echocardiographic mean transvalvular gradient and mitral valve area) were sustained at a mean follow up of 29 months, and there was no documented case of restenosis after successful IBMV. CONCLUSIONS: We conclude that IBMV is safe and effective in juvenile rheumatic MS and provides greater hemodynamic benefit compared with adults; such benefit is sustained during a mean follow up of 29 months.

Adolescent↗
PubMed1996

Transesophageal dobutamine-atropine stress echocardiography: diagnostic accuracy for coronary stenosis detection and localization.

Transesophageal echocardiography with dobutamine-atropine stress (TE-DASE) is a recently described technique for evaluation of coronary artery disease (CAD). We undertook this study prospectively to determine the feasibility, reliability and safety of this procedure in patients with known CAD and to evaluate its diagnostic accuracy for coronary stenoses of varying severity. Thirty-seven patients who underwent coronary arteriography (CART) and TE-DASE within a 3-month interval without intervening ischemic events or revascularisation were included in the study CART and stress echograms were independently evaluated by different observers. Stenosis was measured with calipers and a > or = 50% lumen diameter stenosis was considered significant. A reduction or lack of endocardial motion and/or wall thickening on progressive incremental stress was considered an abnormal response. TE-DASE could be successfully completed in 33/37 (90%) patients. Using a modified 16-segment model of the left ventricle (LV), 15.2 +/- 0.8 segments/patient and 501/528 (95%) segments overall could be optimally evaluated. Inter-observer concordance for an abnormal response was 94%. Predictive accuracies for one-vessel disease (1-VD), two-vessel disease (2-VD) and three-vessel disease (3-VD) were 88, 58 and 23% respectively. Overall sensitivity for detection of a significant (> or = 50%) stenosis was 72% (32% for moderate (50-69%), 90% for severe (> or = 70%) stenosis) and specificity was 96%. Diagnostic accuracy for localisation of significant stenosis was 95% for the left anterior descending artery (LAD), 86% for the left circumflex artery (LCX) and 88% for the right coronary artery (RCA). There were no major complications. We conclude that TE-DASE is a safe, reliable and easily-performed procedure and provides excellent visualisation of myocardial segments. Diagnostic accuracy for detection of severe stenosis and its localisation is excellent.

Atropine↗
PubMed1996

Importance of partitioning membranes of the brain and the influence of the neck in head injury modelling.

A head injury model consisting of the skull, the CSF, the brain and its partitioning membranes and the neck region is simulated by considering its near actual geometry. Three-dimensional finite-element analysis is carried out to investigate the influence of the partitioning membranes of the brain and the neck in head injury analysis through free-vibration analysis and transient analysis. In free-vibration analysis, the first five modal frequencies are calculated, and in transient analysis intracranial pressure and maximum shear stress in the brain are determined for a given occipital impact load.

Biomechanical Phenomena↗
PubMed1996

Use of dopamine in prevention of contrast induced acute renal failure--a randomised study.

We report the use of dopamine in renal doses (5 micrograms/kg/min) to prevent contrast induced nephropathy (CIN). Forty patients with diabetes mellitus who were undergoing coronary angiography were randomly divided into two groups. Gr I (20 patients) was infused with dopamine starting 30 min before cardiac catheterization and continued for 6 h thereafter. Gr II (20 patients) did not receive dopamine. Baseline blood chemistry was performed before catheterization and then repeated 24 h after the procedure. The mean age and sex distribution were similar in both the groups. Urograffin (76%; 120-150 ml) was used in all the cases. The mean serum creatinine and blood urea nitrogen (BUN) levels in Gr I patients before catheterization were 1.5 +/- 0.32 mg % and 16.3 +/- 8.05 mg %, respectively. The corresponding values for Gr II were 1.52 +/- 0.68 mg % and 19.6 +/- 13.4 mg %, respectively. After angiography, Gr I patients did not show significant changes in renal parameters (serum creatinine, 1.37 +/- 0.25 mg % and BUN, 14.7 +/- 5.5 mg %) while Gr II patients showed a significant rise (serum creatinine, 1.96 +/- 1.2 mg % and BUN, 23.25 +/- 12.7 mg %; P = 0.01 and P = 0.05, respectively). Ten patients in Gr II (50%) developed a 25% rise in serum creatinine levels within 24 h of injection of the contrast. None of the patients developed renal failure severe enough to warrant dialysis. Hence alterations of renal function are common after cardiac catheterization. Dopamine in renal doses appears to be an effective means to prevent deterioration in renal function induced by contrast.

Acute Kidney Injury↗
PubMed1996

Three-dimensional time-of-flight MR angiography of the arch of aorta and its major branches: a comparative study with contrast angiography.

The region of the arch of aorta and the intrathoracic course of its major branches was evaluated in 11 patients using three-dimensional time-of-flight magnetic resonance (MR) angiography. Abnormalities such as stenosis, occlusion, dilatation and aneurysm formation were documented in the innominate, both common carotid and both subclavian arteries. The results were compared with those of contrast angiography. There was a good correlation in 47 of the 55 arteries compared. There were five false positive results including overestimation of a stenosis, and three false negative results including underestimation of a stenosis. MR angiography had a sensitivity of 93% and a specificity of 89% for correctly detecting or excluding an abnormality. These results suggest that three-dimensional time-of-flight MR angiography demonstrates lesions in the major branches of the arch of aorta fairly accurately and will prove useful in the initial evaluation and in follow up studies.

Adolescent↗
PubMed1996

Effect of vitamin A supplementation to mother and infant on morbidity in infancy.

OBJECTIVES: To assess the impact of Vitamin A supplementation to the mother soon after delivery and to the infant at six months on morbidity in infancy. DESIGN: Randomized double blind placebo controlled field trial. SETTING: 51 villages in two contiguous Primary Health Centers in Villupuram Health Unit District of Tamil Nadu, South India. SUBJECTS: 909 newly delivered mother-and-infant pairs. INTERVENTIONS: Both mother and infant received Vitamin A (300,000 IU for mothers and 200,000 IU for children) in 311 instances (AA); mother received Vitamin A but infant received Placebo in 301 instances (AP); and both mother and infant received Placebo in the remaining 297 instances (PP). MAIN OUTCOME MEASURES: Incidence of diarrhea and Acute Respiratory Infection (ARI); distributions of infants by frequency of episodes and number of infected days. RESULTS: 233 in the AA Group and 228 each in the AP and PP Groups were followed up regularly. The incidence of diarrhea in these infants was 97.4%, 96.9% and 94.7% in the three groups, mean number of diarrheal episodes was 4.4, 4.6 and 4.2 and median number of days in infancy with diarrhea was 26, 26 and 22 days, respectively. For ARI, the incidences were 96.6%, 95.6% and 96.1%, means were 4.8, 5.1 and 4.8 episodes, and the medians were 32, 34 and 34 days, respectively. CONCLUSIONS: Prophylactic administration of mega doses of Vitamin A to the mother soon after delivery and to the infant at six months do not have any beneficial impact on the incidence of diarrhea and ARI in infancy.

Adult↗
PubMed1995

Changing patterns of group B streptococcal serotypes associated with human infections.

One hundred strains of group B streptococci (GBS) isolated from diverse clinical specimens of patients seen in our hospital were subjected to serotyping by an indigenously prepared coagglutination system. Serotype NT/c was the most predominant (24%), followed by Ia (23%), II/c (12%) and Ib (11%). Type Ia was the most predominant in all specimens except genital samples where NT/c was the most predominant. Comparison of the distribution of serotypes identified during 1975-78 with that of the present study showed a great increase in the prevalence of types NT/c, II/c and Ia and a dramatic decline of types III, Ia/c and Ib. Despite the inclusion of reagents for newer serotypes, IV and V two strains were nontypable indicating the prevalence of hitherto unidentified GBS serotypes in our community.

Humans↗
PubMed1994

Left atrial dilatation in constrictive pericarditis: a pre and post-operative echocardiographic study.

Thirty-three surgically proven cases of constrictive pericarditis were studied pre-operatively by echocardiography for left atrial dilatation and 18 of them underwent post-operative study at a mean follow-up period of 229 +/- 105 days. The degree of left atrial dilatation in these patients was compared with patients of restrictive cardiomyopathy (n = 8) and sex matched controls of similar age (n = 33). Significant left atrial dilatation was present in patients of constrictive pericarditis compared to controls and it was of a similar or greater degree compared to patients of restrictive cardiomyopathy (the left atrium to aorta ratio was 1.7 +/- 0.31, 1.53 +/- 0.18 and 1.07 +/- 0.1, in constrictive pericarditis, restrictive cardiomyopathy and controls, respectively, P = NS for constrictive pericarditis vs. restrictive cardiomyopathy and P < 0.001 for constrictive pericarditis vs. controls). There was no correlation of degree of left atrial dilatation with clinical and hemodynamic variables. Postoperatively, there was regression of left atrial size in patients with normal hemodynamics (n = 12, pre- vs. post-operative left atrium to aorta ratio 1.65 +/- 0.23 vs. 1.32 +/- 0.14, P < or = 0.001) and persisting or increasing left atrial dilatation in patients with persisting hemodynamic abnormality (n = 6, left atrium to aorta ratio 1.66 +/- 0.23 vs. 1.82 +/- 0.15, P = NS). We conclude that significant left atrial dilatation is a consistent echocardiographic feature of constrictive pericarditis. Hemodynamic normalization following successful pericardiectomy is associated with regression of atrial size.

Adolescent↗
PubMed1993

Analysis of hand forces in health and disease during maximum isometric grasping of cylinders.

An analysis of force distribution in the hand during maximum isometric grasping actions is reported in a detailed and accurate manner. A microcomputer-controlled instrument which measures all 12 phalangeal forces of fingers simultaneously, in a single attempt at squeezing a cylindrical object, is described. The study involved 20 normal subjects of different weights and age groups grasping tubes of 50 mm, 75 mm, 90 mm and 110 mm diameters. Normal grasp forces decreased significantly with the increase in tube diameter, with the force being concentrated more on the distal segments of the fingers on the proximal and middle segments. The mean percentage contributions of finger forces to total grip strength, from index to little fingers, were 31, 33, 22 and 14 per cent, respectively. The study was extended to cover leprotic and paralytic hands to assess their functional capabilities. In the case of leprosy subjects, the grip strength decreased with the severity of the disease and was only about 50 per cent of that of normal subjects. In hemiplegics, the grip strength was only about one-eighth of the normal values. The above assessment procedure provides baseline data which could serve as guidelines to a clinician in assessing the severity of the disease and observing the patient's recovery following the treatment. It would also be useful in the design of hand-operated controls and prosthetic arms.

Fingers↗
PubMed1993

Atrio-ventricular regurgitations in constrictive pericarditis: incidence and post-operative outcome.

We studied 33 surgically proven cases of constrictive pericarditis during the period 1989-1991 by color Doppler echocardiography and angiography to look for incidence and postoperative outcome of atrioventricular regurgitation. The mean age was 27.2 + 16.5 years (21 males, 12 females). There was a very high incidence of mitral (79%, trivial in 13, mild in 11 and moderate in 2) and tricuspid (73%, trivial in 7, mild and moderate in 6 each and severe in 5) regurgitation. There was good correlation between 'color Doppler' and angiography for detection and quantification of these regurgitations (r = 0.89 for mitral and 0.76 for tricuspid regurgitation, respectively). There were no preoperative clinical or hemodynamic predictors for the incidence or severity of these regurgitations. Immediate postoperative (7-10 days) evaluation by color Doppler did not show any change in these regurgitations. A follow-up study (by color Doppler and angiography) in 18 patients at a mean period of 229 + 105 days revealed regression of these regurgitations by at least 1 grade in 50% of patients. Patients with persisting regurgitations had persisting hemodynamic abnormality and relatively longer duration of symptoms. The presence of atrio-ventricular regurgitations should not be taken as evidence favoring diagnosis of restrictive cardiomyopathy and against that of constrictive pericarditis. The mechanism of these regurgitations is not clear to us.

Adult↗
PubMed1993

Helicobacter pylori-associated gastritis in Kuwait: endoscopy-based study in symptomatic and asymptomatic children.

Information is limited concerning the prevalence of Helicobacter pylori infection in asymptomatic children. Since January 1989, we have endoscoped 60 children for recurrent abdominal pain or for obtaining small-intestinal biopsy (their ages were a mean of 6.6 (range 9 months-13 years); there were 37 boys and 23 girls. Antral biopsies were obtained from all subjects and these were studied for the presence of gastritis and stained for H. pylori using modified Gram's stain. All biopsies were cultured for H. pylori. Children endoscoped for small-intestinal biopsy (n = 18) were used for comparison. Of the 42 children who had abdominal pain, 24 showed histological gastritis and 13 had H. pylori on microscopy (31% H. pylori-associated gastritis). In the compared group, five showed histological gastritis, and all had H. pylori on microscopy (27.7%). Culture was positive in 15; sensitivity was 85.7%. Six children, three pairs of siblings, had H. pylori gastritis supporting environmental etiology. Two had coinfection with intestinal giardiasis. Seven children were treated with daily oral amoxycillin (50 mg/kg) and tinidazole (20 mg/kg) for 6 weeks. In 3 (42.3%) H. pylori colonization cleared with healing of gastritis and resolution of symptoms. These results indicate that H. pylori gastritis is equally prevalent in symptomatic and asymptomatic children (31 and 27.7%, respectively; p > 0.05) in our population. It seems that the combination of oral amoxycillin and tinidazole is a poor choice in the treatment of H. pylori-associated gastritis in Kuwaiti children.

Abdominal Pain↗