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M Swaminathan

Publications and source records attributed to M Swaminathan.

At least 19 recordsLinked to original sources
PubMed2002

Unusual luminescence characteristics of aminobiphenyls.

Analysis of fluorescence solvatochromic shifts of ortho, meta and para aminobiphenyls reveals that the change in dipolemoment of m-aminobiphenyl on excitation is more when compared to other isomers. This change is due to the resonance interaction of unsubstituted phenyl ring with -NH2 group at meta position in the excited singlet state. The fluorimetric titration curves of three aminobiphenyls are found to be different from each other. The stretched sigmoidal curves obtained for m-aminobiphenyl indicates that the rates of proton transfer in S1 state are comparable to the rates of fluorescence.

Aminobiphenyl Compounds↗
PubMed2002

Hypocarbia in the ventilated preterm infant and its effect on intraventricular haemorrhage and bronchopulmonary dysplasia.

OBJECTIVE: To examine the relationship between PaCO2 levels in ventilated very preterm infants and (i) the incidence of severe intraventricular haemorrhage (IVH) and periventricular leukomalacia (PVL); and (ii) bronchopulmonary dysplasia (BPD). METHODS: A retrospective cohort analysis of preterm infants comparing PaCO2 levels with the incidence of severe IVH/PVL and BPD was carried out on patients born at less than 29 weeks gestation from 1992 to 1994 and admitted to the tertiary neonatal intensive care unit at the King Edward Memorial Hospital (314 infants). During the first 96 h, PaCO2 levels were examined including lowest and highest PaCO2 levels, mean PaCO2 levels and duration of hypocarbia both pre- and post-surfactant administration. RESULTS: Of the 314 infants, there were 40 early neonatal deaths (less than 48 h) who were not included in the analysis. Of the 274 surviving infants, 72 (26%) infants had severe IVH. Infants whose PaCO2 fell below 30 mmHg at any stage in the first 48 h of life had an increased risk of severe IVH or PVL (odds ratio 2.38; 95% CI 1.27-4.49; P = 0.007). Of the 265 survivors to 36 weeks corrected gestational age, 134 (51%) had BPD. Infants with at least three PaCO2 values less than 30 mmHg in the first 24 h of life had an increased risk of BPD (odds ratio 2.21; 95% CI 1.05-4.57; P = 0.036). CONCLUSIONS: The risk of severe IVH/PVL was significantly increased by hypocarbia. There was also an association between hypocarbia and BPD, particularly when hypocarbia was prolonged. These findings suggest that avoidance of hypocarbia may reduce the incidence of severe IVH/PVL and BPD in preterm infants.

Bronchopulmonary Dysplasia↗
PubMed2001

Report of a substudy on warm versus cold cardiopulmonary bypass: changes in creatinine clearance.

BACKGROUND: Renal dysfunction remains a major complication of cardiac operations. There is concern regarding the possibility of increased renal injury during warm cardiopulmonary bypass (CPB). Therefore, we tested the hypothesis that warm CPB is associated with a greater reduction in creatinine clearance after cardiac surgery than hypothermic CPB. METHODS: We randomly assigned 300 patients who had elective coronary artery bypass grafting to warm (35.5 to 36.5 degrees C) or cold (28 degrees C to 30 degrees C) CPB. Preoperative and peak postoperative serum creatinine values were recorded. Creatinine clearance was estimated using the Cockroft Gault equation. Univariate and multivariable analyses were performed to test the association of CPB temperature and perioperative change in creatinine clearance. RESULTS: Demographic variables were similar between groups. Multivariable analysis did not confirm an association between temperature and change in creatinine clearance (p = 0.87). CONCLUSIONS: We did not confirm an association between warm CPB and increased renal dysfunction after cardiac operations compared with hypothermic CPB.

Aged↗
PubMed2001

Spectral characteristics of 2-aminodiphenylamine in different solvents and at various pH values.

The absorption and fluorescence spectra of 2-aminodiphenylamine (2ADA) have been studied as a function of solvent polarity and acid concentration. Analysis of solvatochromic and prototropic shifts of 2ADA reveals: (i) the presence of intramolecular hydrogen bonding between imino and amino groups in the ground state, (ii) dual fluorescence (360 and 430 nm) of the monocation (2ADA+) formed by the protonation of amino group; and (iii) proton-induced quenching of the monocation (2ADA+) fluorescence. In the dual fluorescence of 2ADA+, the longer wavelength emission at 430 nm is found to be from the twisted form of the monocation. The rate constants of the proton-induced quenching of 2ADA+ are determined.

Hydrogen-Ion Concentration↗
PubMed2001

Measurement of the transverse cerebellar diameter in preterm neonates and its use in assessment of gestational age.

This study aims to confirm the relationship between gestational age (GA) and transverse cerebellar diameter (TCD), to define the prediction of GA by TCD, and assess the reliability of TCD measurements. Infants were included in the study if they had a routine cranial ultrasound scan by day 3, and the TCD was measured. Infants were excluded from the study if the GA was not known, if there was any cranio-spinal malformation or grade 3 or 4 intraventricular haemorrhage (IVH). The GA assessment was an early pregnancy scan or certain dates. Cranial ultrasound scans were done with a LOGIQ 500 scanner (GE Medical Systems, Waukesha, WI, USA) with a 7 MHz curvilinear sector probe (GE LOGIQ-C721; GE Medical Systems). The posterior fossa was scanned using the asterion as the acoustic window with the TCD measured in the coronal plane. Intra- and interobserver reliability were assessed. A total of 221 infants of known GA had their TCD measured. The linear regression for GA versus TCD is: GA(weeks) = (0.470 x TCD(millimetres)) + 13.162 (r = 0.89, r(2) = 0.79, P < 0.001). The 95% confidence interval predicts GA to +/- 2.33 weeks for a given TCD. Intra- and interobserver intraclass correlation coefficients are 0.98 and 0.99, respectively. Transverse cerebellar diameter correlates closely with GA and predicts GA to +/- 2.33 weeks. Measurements of TCD have excellent reproducibility.

Cephalometry↗
PubMed2000

A preliminary study of the application of the transductal velocity ratio for assessing persistent ductus arteriosus.

OBJECTIVE: To compare the transductal velocity ratio (TVR) of the persistent ductus arteriosus (PDA) with other echocardiographic criteria for haemodynamic significance of a PDA. METHODS: This was a prospective study (from January 1997 to August 1998) in the nurseries of the Royal Women's Hospital, Melbourne. Infants with a clinically suspected PDA were eligible and included if the echocardiogram showed a PDA with a structurally normal heart and the TVR had been measured. The PDA was assessed for evidence of left heart dilatation, the presence of reverse or absent diastolic flow in the descending aorta, the pattern of Doppler flow velocity waveform in the ductus arteriosus, and subjective assessment of ductal diameter on the real time image. The peak systolic velocity (PSV) was obtained from the pulmonary and aortic ends of the PDA, and the TVR calculated by dividing the PSV at the pulmonary end by the PSV at the aortic end. RESULTS: Forty two infants had 59 echocardiographs with their TVR calculated. Mean (SD) birth weight was 1008 (362) g. Mean (SD) gestational age at birth was 27.4 (2.2) weeks with a mean (SD) corrected gestational age of 28.7 (2.7) weeks. The mean TVR was decreased in those infants with a high left atrial diameter/aortic diameter (LA/Ao) ratio (1.9 v 2.8, p = 0.0032) or reverse/absent diastolic flow in the descending aorta (2.1 v 3.0, p = 0.02). This difference was greater if those two criteria were combined (1.7 v 3.4, p = 0.0027). The mean TVR was decreased in infants with a wide open duct seen on two dimensional imaging (1.5 v 3.0, p < 0.0001) or pulsatile flow seen on pulsed Doppler in the PDA (1.9 v 3.4, p = 0.0001). The LA/Ao and left ventricle internal diameter/aortic diameter (LVIDd/Ao) ratios were higher in the group with a TVR < 1.8 than in the other two groups; these differences were statistically significant. CONCLUSIONS: The TVR as a measure of the degree of constriction of a PDA is associated with other echocardiographic criteria for a haemodynamically significant PDA. A low TVR (signifying a poorly constricted duct) is associated with echocardiographic features of a significant left to right shunt, and vice versa. Further research is required to determine the usefulness of the TVR in predicting closure or likely continuing patency of a PDA and the need for treatment.

Birth Weight↗
PubMed2000

Reference ranges for the linear dimensions of the intracranial ventricles in preterm neonates.

AIMS: To establish normal ranges, in preterm infants < 33 weeks' gestation, for measurements of the lateral, third, and fourth ventricles and to assess intra-observer and inter-observer reliability. To assess the effect of head position during scanning on lateral ventricle size. To determine whether sex influences ventricle size. METHODS: A prospective study involving infants < 33 weeks' gestational age (GA) at birth. Cranial ultrasound scans were done during the first 3 days of life. Linear dimensions of the anterior horn width and thalamo-occipital distance of the lateral ventricles, the width of the third ventricle, and the width and length of the fourth ventricle were measured. Measurements were plotted against GA and reference ranges produced. All measurements were tested for intra-observer and inter-observer reliability. Head position and sex differences were studied. RESULTS: 120 infants with known GA (23(+1) to 32(+6) weeks) had their intracranial ventricles measured. Reference ranges obtained were-anterior horn width: 0-2.9 mm; thalamo-occipital distance: 8.7-24.7 mm; third ventricle width: 0-2.6 mm; fourth ventricle width: 3.3-7.4 mm; fourth ventricle length: 2.6-6.9 mm. Dependent and non-dependent lateral ventricles did not differ significantly in size. There was no clinically significant difference in ventricular size between sexes. CONCLUSIONS: Reference ranges for the measurement of the intracranial ventricles in preterm infants from 23 to 33 weeks' GA are provided and can be used in the diagnosis and assessment of ventricular enlargement in preterm infants. All measurements have good intra-observer and inter-observer reliability. Head position at the time of scanning does not influence the asymmetry of the lateral ventricular measurements. The infant's sex does not influence ventricular size.

Cerebral Ventricles↗
PubMed1999

Transverse cerebellar diameter on cranial ultrasound scan in preterm neonates in an Australian population.

OBJECTIVE: Fetal measurement of transverse cerebellar diameter (TCD) has been shown to correlate well with gestational age (GA), even in the presence of growth retardation. The aim of this study was to define the normal range of TCD in preterm neonates in an Australian population between 23 and 32 weeks GA. METHODOLOGY: Infants admitted to the Royal Women's Hospital, Melbourne, having routine cranial ultrasound scans (< 1500 g and/or of gestational age </= 32 weeks at birth) had their TCD measured on a cranial scan performed during the first 3 days of life. The posterior fossa was examined through the asterion using a General Electric LOGIQ 500 scanner (GE Medical Systems, Waukesha, USA) and TCD measurement was taken in the coronal plane. RESULTS: 106 infants < 1500 g and/or of GA </= 32 weeks at birth had their TCD measured between 1 January 1997 and 30 November 1997. Transverse cerebellar diameter and associated 95% confidence intervals are described for infants between 23 and 32 weeks GA. The linear regression equation relating TCD and GA was: TCD (mm) = -12.9 + 1.61 x GA (weeks). R2 = 0.80, P < 0.001. CONCLUSION: This is the only study of TCD measurement using cranial ultrasound in a group of preterm newborns, and forms the basis for nomograms of TCD which can be used as a tool to assist in the assessment of GA, even in growth-retarded preterm newborns, and in the diagnosis of cerebellar hypoplasia.

Cephalometry↗
PubMed1998

A comparative evaluation of intrapleural and thoracic epidural analgesia for postoperative pain relief after minimally invasive direct coronary artery bypass surgery.

OBJECTIVE: To compare the efficacy of thoracic epidural analgesia (TEA) and intrapleural analgesia (IPA) after minimally invasive direct coronary artery bypass (MIDCAB) surgery with regard to quality of analgesia and complications. DESIGN: A prospective, randomized study. SETTING: A specialty research hospital. PARTICIPANTS: Fifty consenting adults scheduled for MIDCAB surgery. INTERVENTIONS: All patients underwent elective MIDCAB surgery. Patients in the TEA group (n=25) had an epidural catheter inserted in the fourth to fifth thoracic interspace and those in the IPA group (n=25) had an intrapleural catheter inserted in the sixth to seventh intercostal space intraoperatively under vision. MEASUREMENTS AND MAIN RESULTS: Parameters evaluated after administration of bupivacaine (8 mL of 0.25% in the TEA group and 20 mL of 0.25% in the IPA group) on first demand included visual analog scale (VAS) pain scores, cardiovascular and respiratory (clinical, blood gases) function, wakefulness, supplemental analgesic requirement, and complications. Measurements were made at 2-hour intervals for the next 12 hours. VAS scores were significantly lower at 2, 6, 8, and 12 hours in the IPA group (TEA = 3.5, 4.5, 4.9, 4.6; IPA = 2.2, 3.6, 3.5, 3.7). There were no significant differences in hemodynamic or respiratory parameters or postoperative requirement for supplemental analgesia. In the TEA group, three patients had catheter migration and four had severe backache. CONCLUSION: IPA is a safe and effective technique for postoperative analgesia after MIDCAB surgery and has a low complication rate compared with TEA. Careful positioning, chest tube clamping, and anchoring of the catheter are mandatory for IPA to be effective.

Analgesia, Epidural↗
PubMed1995

Djenkol bean poisoning (djenkolism): an unusual cause of acute renal failure.

This report describes a patient with acute renal failure that resulted from the ingestion of djenkol beans. Features of acute djenkolism include nausea, vomiting, bilateral loin pain, gross hematuria, and oliguria. The blood urea level was 16.2 mmol/L and the serum creatinine was 460 mumol/L. Phase contrast microscopy of the urinary sediment indicated that the hematuria was nonglomerular. Ultrasound of the kidneys showed slightly enlarged kidneys with no features of obstruction. Renal biopsy showed acute tubular necrosis similar to the single animal study reported in the literature. With conservative therapy, which included rehydration with normal saline and alkalinization of the urine with sodium bicarbonate, the acute renal failure resolved. Based on its chemistry, djenkol bean-associated acute renal failure may be analogous to acute uric acid nephropathy.

Acute Kidney Injury↗
PubMed1995

Algorithm for managing a baby with dusky soles.

We have been using dusky colour of the sole in newborns as proxy to cyanosis. An algorithm for management of dusky soles was developed presupposing that a baby can have dusky soles due commonly to hypothermia, hypoxaemia, or hypotension in isolation or in combination. Fifty-one consecutive babies were managed according to a predetermined algorithm based largely on clinical signs. Forty babies were covered by these three broad groups and 37 of them could be managed successfully. Of the remaining babies two were found to have congenital malformations on autopsy and one died of hyperthermia. Algorithmic approach has simplified the management with low failure rate and can be useful when hi-tech neonatal care is unaffordable.

Algorithms↗
PubMed1994

Acute renal failure in falciparum malaria.

We report two patients who had cerebral malaria, heavy parasitemia, hyperbilirubinemia, hypercatabolism with rapid rises of blood urea and serum creatinine and acute renal failure. There was no evidence of intravascular hemolysis. Renal biopsy was consistent with acute tubular necrosis. Both patients responded to treatment with intravenous quinine and dialysis.

Acute Kidney Injury↗
PubMed1992

Duodenal leiomyosarcoma: a report of a rare and aggressive tumour.

A 45-year-old Malay lady who presented with intermittent abdominal pain and a left hypochondrial mass was found to have a 10 x 8 x 5 cm duodenal tumour without local invasion at laparotomy. En bloc resection of the tumour with adequate margin of clearance was done and histopathological diagnosis of low grade leiomyosarcoma was made. Fourteen months later, she returned with multiple metastases in the liver and needed palliative chemotherapy for pain relief. Duodenal leiomyosarcomata are very rare tumour. Their prognostic indicators include biological grading, tumour size and presence of metastases. Recognition of its high malignant potential calls for close surveillance calls even after apparent curative surgery.

Duodenal Neoplasms↗
PubMed1988

Ivermectin for the treatment of Wuchereria bancrofti filariasis. Efficacy and adverse reactions.

Ivermectin treatment was evaluated for efficacy and side effects in 40 patients in South India who had microfilaremia and bancroftian filariasis. Ivermectin was administered once orally at four dose levels (range, 25 to 200 micrograms/kg), and at each it was found to be completely effective in clearing blood microfilariae within five to 12 days. In most patients, microfilariae reappeared by three months; by six months the levels averaged 14% to 32% of pretreatment values in the four study groups, and all groups showed equivalent efficacy. Detailed monitoring identified some side effects in almost all patients: usually fever, headache, light-headedness, myalgia, sore throat, or cough that occurred most prominently 18 to 36 hours after treatment. These were most frequent and severe in patients with the greatest microfilaremia, but only when treated with the two higher doses of ivermectin (100 and 200 micrograms/kg). The low-dose (25 micrograms/kg) ivermectin group, despite equivalent efficacy in parasite killing, had clinical reaction scores that were minimal and that were not correlated with parasitemia. Since efficacy and side effects of ivermectin therapy compare favorably with those reported for treatment with the standard antifilarial drug diethylcarbamazine citrate, the major advantage of single-oral-dose administration makes ivermectin the best candidate to replace diethylcarbamazine as the treatment of choice for bancroftian filariasis.

Adult↗