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Biomedical subjects

V Jaganathan

Publications and source records attributed to V Jaganathan.

11 recordsLinked to original sources
PubMed2005

A novel multiple frequency stimulation method for steady state VEP based brain computer interfaces.

The objective is to increase the number of selections in brain computer interfaces (BCI) by recording and analyzing the steady state visual evoked potential response to dual stimulation. A BCI translates the VEP signals into user commands. The frequency band from which stimulation frequency can be selected is limited for SSVEP. This paper discusses a method to increase the number of commands by using a suitable combination of frequencies for stimulation. A biopotential amplifier based on the driven right leg circuit (DRL) is used to record 60 s epochs of the SSVEP (O(z)-A(1)) on 15 subjects using simultaneous overlapped stimulation (6, 7, 12, 13 and 14 Hzs and corresponding half frequencies). The power spectrum of each recording is obtained by frequency domain averaging of 400 ms SSVEPs and the spectral peaks were normalized. The spectral peaks of the combination frequencies of stimulation are predominant compared to individual stimulating frequencies. This method increases the number of selections by using a limited number of stimulating frequencies in BCI. For example, six selections are possible by generating only three frequencies.

Adult↗
PubMed2005

Role of transthoracic Doppler pulmonary venous flow pattern in large atrial septal defects.

OBJECTIVE: Large uncomplicated atrial septal defect (ASD) alters the pulmonary venous flow (PVF) pattern. We aimed to study the role of transthoracic echocardiography (TTE) in estimating the PVF Doppler abnormalities in ASD. By repeating the study soon after ASD closure, we correlated the hemodynamics of atrial shunting with PVF patterns. METHODS: This study was performed in a tertiary care referral teaching hospital in 2003. The TTE PVF patterns of 34 patients with ASD were studied. TTE study was reported by two blinded investigators independently. Surgical closure of ASD was done on eleven patients and the early postoperative PVF Doppler pattern was also studied with TTE. RESULTS: PVF patterns were adequately recorded in 34 of 38 (90%) subjects with ASD with equal male: female ratio (n = 17 each). The mean age of the study group was 21.4 +/- 8.7 years. ASD ranged from 10 to 38 mm in diameter with a mean of 18 +/- 4.2 mm. Continuous antegrade wave (CAW, mean 68.45 +/- 13.6 cm/s) replaced normally occurring S and D waves in all ASD patients. The atrial reversal wave was reduced or absent (mean 20.18 +/- 3.28 cm/sec). After ASD closure, the CAW was replaced by the S (46.18 +/- 7.5 cm/sec) and D waves (57.72 +/- 9.7 cm/sec) with increase in atrial reversal wave to 27.81 +/- 5.1 cm/sec. CONCLUSIONS: The S and D antegrade waves normally seen in PVF are replaced by a continuous antegrade wave in ASD. Atrial reversal wave is also reduced. PVF waveform becomes normal after ASD closure. TTE PVF Doppler pattern can help estimate ASD hemodynamics.

Adolescent↗
PubMed1992

Excretion of cefprozil into human breast milk.

The excretion of cefprozil into breast milk in nine healthy, lactating female subjects was investigated. Each subject received a single 1,000-mg oral dose of cefprozil consisting of cis and trans isomers in an approximately 90:10 ratio. Serial blood, urine, and breast milk samples were collected and analyzed for the concentrations of the cis and trans isomers by a specific high-pressure liquid chromatography-UV assay. The mean pharmacokinetic parameters for both isomers were essentially the same. The mean peak concentrations in plasma for the cis isomer were 14.8 micrograms/ml, and the area under the concentration curve was 54.8 micrograms.h/ml. The mean values of elimination half-life, renal clearance, and urinary excretion for the cis isomer were 1.69 h, 164 ml/min, and 60%, respectively. The mean concentrations in milk of the cis isomer over a 24-h period ranged from 0.25 to 3.36 micrograms/ml, with the maximum concentration appearing at 6 h after dosing. The average maximum concentration in milk of the trans isomer was less than 0.26 micrograms/ml. The concentrations of the trans isomer in plasma and in breast milk were about 1/10 of those for the cis isomer. Less than 0.3% of the dose was excreted in breast milk for both isomers of cefprozil. Even if one assumes that the concentration of cefprozil in milk remains constant at 3.36 micrograms/ml (the highest concentration of cefprozil observed in breast milk), an infant ingesting an average of 800 ml of milk per day will be exposed to a maximum amount of about 3 mg of cefprozil per day. This value represents about 0.3% of the maternal dose. Low excretion of cefprozil in breast milk and the excellent safety profile of cefprozil suggest that this cephalosporin may be administered to nursing mothers when indicated.

Administration, Oral↗
PubMed1983

A case of ST-segment and T-wave alternans.

A 45-year-old man was admitted to the Government General Hospital, Madras, India, for Prinzmetal's angina. His condition was not responding to the combined treatment of isosorbide dinitrate and propranolol hydrochloride he had been taking one week before admission to the hospital. During his stay in the intensive care unit, 23 episodes of ST-segment elevation occurred. Three episodes showed ST-segment and T-wave alternans, a phenomenon, which, to our knowledge, have not been described. The patient was treated with verapamil hydrochloride and phenoxybenzamine hydrochloride, and he responded well. His condition continued to be stable during a two-year follow-up. A review of the literature and a discussion of this ECG phenomenon is presented.

Angina Pectoris, Variant↗
PubMedDate not supplied

Safety and efficacy of enalapril in multivalvular heart disease with significant mitral stenosis--SCOPE-MS.

Angiotensin-converting enzyme inhibitors (ACEI) are often used in preventing and treating heart failure due to regurgitant valve disease. The majority of patients with symptomatic rheumatic heart disease (RHD) have significant mitral stenosis (MS) and are denied ACEI therapy, because of the fear of hypotension in the presence of fixed obstruction. The authors assessed the safety and efficacy of ACEI in 109 consecutive patients with RHD and with significant mitral stenosis (mitral valve orifice, MVO < 1.5 cm2)and with NYHA class III or IV heart failure symptoms. Mean age was 33.1+/-12 years, systolic blood pressure (BP) was 111+/-10, and diastolic BP was 73+/-8 mm Hg. MS was significant in 100 patients with mitral regurgitation in 46, aortic regurgitation in 19, and pulmonary hypertension in 60 patients. After initial stabilization, enalapril 2.5 mg bid was started in hospital and titrated up to 10 mg bid over 2 weeks. NYHA status, Borg score, and 6-minute walk test were assessed at baseline, and at 1, 2, and 4 weeks. Seventy-nine of the 100 patients who completed the study had severe MS (MVO < 1.0 cm2). Enalapril was well tolerated by all study patients without hypotension or worsening of symptoms. NYHA class (3.2+/-0.5 baseline vs 2.3+/-0.5 at 4 weeks, p < 0.01) Borg Dyspnea Index (7.6+/-1.3 vs 5.6+/-1.3, p < 0.01), and 6-minute walk distance (226+/-106 vs 299+/-127 m, p < 0.01) improved significantly with enalapril. Patients with associated regurgitant lesions showed more improvement in exercise capacity (120+/-93 vs 39+/-56 m, p < 0.001). Enalapril was well tolerated in patients with RHD with moderate and severe MS. Irrespective of the valve pathology, enalapril improved functional status and exercise capacity with maximum benefit in patients with concomitant regurgitant valvular heart disease.

Adult↗
PubMedDate not supplied

Patterns and predictors of prehypertension among "healthy'' urban adults in India.

Cardiovascular disease is still on the increase in India owing to changing socioeconomic factors and unhealthy lifestyles. Better understanding of the role of hypertension (HTN) has led to new Joint National Committee (JNC-7) guidelines for its diagnosis and management. The authors aimed to evaluate the predictors and correlates of prehypertension (PreHTN) among adults in urban India. Study design is a cross-sectional survey among 2,007 adults in Chennai in July 2003; 1,505 men and 502 women over the age of 18 years were studied. Demographic data collected by direct interview were the following: age, smoking, alcohol intake, type of work, exercise patterns, and monthly income. Anthropometric data of height, weight, and waist and hip dimensions were measured. Blood pressure (BP) was recorded thrice, with at least 15 minutes between readings 2 and 3. The mean of readings 2 and 3 was taken for the study. Of the 2,007 people studied, 951 (47.4%) had PreHTN and 696 (34.7%) had HTN. PreHTN was found in 46.6% of the men and 49.8% of the women. PreHTN was prevalent in 47.4% of adults, and another 34.7% had hypertension (Stage I, 20%, and Stage II, 14.7%). In urban India less than 18% of adults have normal BP of less than 120/80. Multiple logistic regression analysis after age and sex correction identified obesity, diet, family history and middle-income group as correlating with PreHTN. The factors that predict HTN were age, sex, smoking, alcohol intake, sedentary lifestyle, and type of work.

Adult↗
PubMedDate not supplied

Severe left ventricular dysfunction in left atrial myxoma--report of 2 cases.

We report 2 patients with left atrial (LA) myxoma with associated severe left ventricular (LV) dysfunction. Both presented with progressive effort intolerance without a history suggestive of acute coronary event. LA myxoma was diagnosed by transthoracic echocardiography, which also detected severe systolic dysfunction and LV dilatation. Regional wall motion abnormality and thinning were absent. Coronary angiograms also showed no occlusive disease, but distal ectasia was seen in 1 patient. Metabolic and endocrine causes of reversible LV dysfunction were excluded. Cardiac function improved following surgery for myxoma in 1 patient. LV dysfunction, thus far, has not been directly attributed to myxoma. Coronary embolization leading to myocardial infarction and coexisting coronary atherosclerosis are the recognized methods by which LV dysfunction manifests in myxoma. Our report suggests the possibility of reversible severe global LV dysfunction due to cardiodepressant effect of myxoma through as yet unclear mechanisms.

Adult↗