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Biomedical subjects

P Ramachandran

Publications and source records attributed to P Ramachandran.

At least 19 recordsLinked to original sources
PubMed1997

Congenital malformations of the lung and mediastinum--a quarter century of experience from a single institution.

Congenital malformations of the lung are rare and vary widely in their presentation and severity. The authors reviewed 25 years of experience with specific reference to diagnosis, treatment, and outcome. From July 1970 to June 1995, 70 patients were diagnosed with congenital malformations of the lung, which included sequestration (n = 20), foregut anomalies (n = 20), congenital lobar emphysema (CLE; n = 10), congenital cystic adenomatoid malformation (CCAM; n = 5), benign lung cysts (n = 6), lung aplasia/ hypoplasia (n = 4), and other miscellaneous disorders (n = 5). All patients with pulmonary hypoplasia presented at birth. With the exception of one patient, infants with CCAM and CLE presented before 5 months of age. All other patients presented from birth to 16 years of age. A prenatal diagnosis was accurate in two patients. Although prompt surgical management is the rule, the exceptions were children with bilateral lung involvement. Corrective surgery was delayed in some patients in whom extended respiratory support was required or in whom the delay led to an increase in pulmonary reserve. Extracorporeal membrane oxygenation (ECMO) was used in two patients pre- and postoperatively to manage persistent pulmonary hypertension. This review, representing the largest series of congenital lung lesions, showed that (1) prenatal diagnosis is useful but generally does not change the outcome; (2) computerized tomography (CT) is the optimum postnatal diagnostic imaging modality if chest radiography is not definitive; (3) ECMO can be an adjunct in treating associated pulmonary hypertension; (4) pulmonary resection (lobectomy) is the surgical procedure of choice for most lesions; (5) expected survival is good; and (6) pulmonary hypertension is the most common cause of mortality.

Adolescent↗
PubMed1996

Role of O-acetyltransferase in activation of oxidised metabolites of the genotoxic environmental pollutant 1-nitropyrene.

The genotoxic environmental contaminant 1-nitropyrene is metabolised in mammalian systems by pathways more complex than the straightforward nitroreduction which accounts for most of its biological activity in bacteria. In order to evaluate the role of O-acetyltransferase (OAT) activity in generation of genotoxic intermediates from 1-nitropyrene, the mutagenicity of the major primary oxidised metabolites of 1-nitropyrene was characterised in the Ames Salmonella typhimurium plate incorporation assay with strain TA98, and with variants of TA98 deficient (TA98/1,8-DNP6) or enhanced (YG1024) in O-acetyltransferase. 1-Nitropyren-3-ol was more mutagenic in the absence than in the presence of S9, while 1-nitropyren-4-ol, 1-nitropyren-6-ol and 1-nitropyren-8-ol required S9 for maximum expression of mutagenicity. 1-Nitropyren-4-ol (176 rev/nmol without S9, 467 rev/nmol with S9 in TA98) and 1-nitropyren-6-ol (13 rev/nmol without S9, 266 rev/nmol with S9 in TA98) were overall the most potent nitropyrenol isomers assayed. 1-Acetamidopyren-8-ol and 1-acetamidopyrene 4,5-quinone were only minimally active. 1-Acetamidopyren-3-ol exhibited direct-acting mutagenicity. 1-Acetamidopyren-6-ol, previously shown to be a major contributor to mutagenicity in the urines of rats dosed with 1-nitropyrene (Ball et al., 1984b), was confirmed as a potent (359 rev/nmol) S9-dependent mutagen. Both the direct-acting and the S9-dependent mutagenicity of all the compounds studied was enhanced in the OAT-overproducing strain and much diminished (though not always entirely lost) in the OAT-deficient strain, showing that OAT amplifies expression of the genotoxicity of these compounds. 1-Acetamidopyren-6-ol required both S9 and OAT activity in order to exhibit any mutagenicity; this finding strongly implicates N-hydroxylation followed by O-esterification, as opposed to further S9-catalyzed ring oxidation, as a major route of activation for urinary metabolites of 1-nitropyrene.

Acetyltransferases↗
PubMed1996

High performance liquid chromatographic assay of amprolium and ethopabate in chicken feed using solid-phase extraction.

A method for the assay of mixtures of amprolium and ethopabate in chicken feed was developed utilizing reversed-phase high-performance liquid chromatography (HPLC) after sample clean-up of a methanolic extract by solid-phase extraction using CN cartridges. HPLC was done with benzocaine as internal standard on a C-8 column with methanol-water 40:60, containing octanesulfonic acid, triethylamine and acetic acid, as mobile phase. Eluate was monitored at 274 nm. Baseline separation was achieved with retention times of approximately 7.5, 9.4, and 10.4 min, for amprolium, benzocaine, and ethopabate respectively. Feed constituents did not give peaks after 6.5 min. Peak area ratios were linear over 10-180 ng of amprolium, and 2-18 ng of ethopabate injected. Limits of quantitation at AUFS 0.05 were 0.5 and 0.3 ng respectively. Recovery studies from spiked feed (n = 9), covering +/- 30% of usual doses in feed, gave percent recoveries (+/- SD) of 99.4 +/- 1.4% for amprolium and 100.5 +/- 2.6% for ethopabate. Applying the method to two different batches of commercial feed gave results which were comparable to those obtained by the AOAC spectrofluorometric methods.

Amprolium↗
PubMed1996

Ultrasonography as an adjunct in the diagnosis of acute appendicitis: a 4-year experience.

This study was designed to evaluate the sensitivity and specificity of abdominal ultrasonography as a diagnostic modality in a large series of children who presented with possible appendicitis. From August 1990 to July 1994, 452 children (203 boys, 249 girls) with an average age of 11 years (range, 1 to 20 years) underwent graded compression ultrasonography of the right lower quadrant of the abdomen for the evaluation of possible appendicitis. In the first 18 months of the study all patients with the possible diagnosis of appendicitis (group I; 180 patients) had abdominal ultrasonography after members of the surgical team evaluated and documented their findings in the medical record. In the second study period (30 months), abdominal ultrasonography was recommended only when the clinical diagnosis of acute appendicitis was equivocal (group II; 272 patients). Abdominal ultrasonography was performed using the graded compression technique with a 5.0-MHz linear array transducer. A positive ultrasound study for appendicitis was defined as the presence of an enlarged noncompressible appendix with an outer wall to outer wall diameter of greater than 6 mm, the presence of a complex mass, or the presence of an appendicolith. The sonographic data were correlated with surgical and pathological findings. Appendicitis was confirmed in 112 of the 452 cases. In 17 of these, the appendix was perforated. In the overall group of 452 children, abdominal ultrasonography had a sensitivity of 90%, specificity of 96%, and accuracy of 95%. There was no significant morbidity in the 11 patients with a false-negative study result. All 11 patients had an uncomplicated appendectomy. There were 11 false-positive results; 10 of these patients had a negative laparotomy result (negative laparatomy rate, 8.9%). For the two groups, the sensitivity and specificity of ultrasonography in the diagnosis of appendicitis were equivalent (group 1: 88% sensitivity, 96% specificity; group 2: 92% sensitivity, 97% specificity). On the basis of the high sensitivity and specificity rates, ultrasonography of the appendix can be a useful adjunct to standard examination in the diagnosis of acute appendicitis.

Abdominal Pain↗
PubMed1995

Acute Abdomen.

Abdominal pain is a common complaint in adolescents, and its evaluation is challenging. This article provides a method of evaluating the adolescent with acute abdominal pain, reviews the more common causes that may lead to surgical intervention, and provides algorithms for determining a specific diagnosis and mode of treatment.

Journal Article↗
PubMed1994

Health consequences of vasectomy in India.

Vasectomy acceptance has been declining in India during the past 20 years. Even if the risk of prostate cancer is marginally higher in vasectomized men, this risk in India has to be assessed against the immediate safety and other possible long-term benefits of this procedure. The Indian Council of Medical Research has launched a case-control study, which is unlikely to be time-consuming or beyond the available means and resources, in order to obtain definitive data on this problem. Meanwhile, vasectomy remains an excellent procedure for the couple seeking permanent methods of contraception, and specific efforts to promote its acceptance must continue in India.

Case-Control Studies↗
PubMed1993

Growth of urban breastfed infants from low socio-economic group.

Breastfeeding has been considered the best mode of feeding the infant. In traditional countries like India, it has been the tradition among poor income groups of women and the universal adage breast feed as long as possible goes uncontested. However, the appropriate age at which supplementation should start is replete with controversy and varies between as early as 3-6 months. While the debate on when should supplementation be started continues, it is also important to know if the nutritional benefit is expressed in terms of growth of the infant, under the existing unhygienic conditions. This study was therefore undertaken.

Adult↗
PubMed1993

The epidemiology of AIDS in the Vellore region, southern India.

OBJECTIVE: To describe the epidemiology of patients with AIDS in Vellore region, Southern India. DESIGN AND METHODS: Sixty-one patients with AIDS were diagnosed and treated between July 1987 and June 1992. Information on their demographic characteristics and probable modes of acquiring HIV infection was collected at interviews with them and their spouses. RESULTS: There was a progressive increase in the number of patients seen over the 5 years. The mean ages of the 51 men and the 10 women were 33 and 29 years, respectively. Of the 44 patients from our district (population, 5 million), 28 were from Vellore town and 10 from rural areas. Forty-seven (92%) men had frequently used prostitutes. Of the women, four were prostitutes, one had had multiple sex partners and five had not had extramarital sexual contact. One man and one woman had no other risk factor except blood transfusion. Thirty-one (51%) patients had died by August 1992. CONCLUSION: The AIDS epidemic in this region is in its early ascending phase, with a doubling time of approximately 1 year. Most men with AIDS were infected by heterosexual contact with prostitutes, while some women were prostitutes themselves. Together with the male-to-female ratio of 5:1, these results suggest that the male population at risk has sex with a much smaller population of female prostitutes, constituting the major chain of transmission. HIV infection is occurring in both urban and rural populations.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Trisomy 22 with congenital diaphragmatic hernia and absence of corpus callosum in a liveborn premature infant.

We report on a liveborn premature male with trisomy 22 who had multiple congenital anomalies, including congenital diaphragmatic hernia and absence of corpus callosum. He died of pulmonary hypoplasia associated with diaphragmatic hernia within 12 hours of age. Chromosome analysis by multiple banding techniques based on lymphocyte culture confirmed that he had trisomy 22. This may be the first report of congenital diaphragmatic hernia and isolated absence of corpus callosum associated with trisomy 22.

Abnormalities, Multiple↗
PubMed1992

Defaults, defaulter action and retrieval of patients during studies on tuberculous meningitis in children.

Chemotherapy studies were undertaken on 180 children, aged between 1 and 12 years, with tuberculous meningitis. They received therapy for 12 months. As approximately one-half of the patients came from outside Madras city, retrieval action was not possible in all cases of default. Despite this, a high rate of compliance and punctuality was achieved as a result of initial and periodic motivation. This report highlights the role and importance of motivation in the prevention of default and the retrieval of defaulters during the treatment of children with tuberculous meningitis.

Antitubercular Agents↗
PubMed1991

Effect of vascular puncture on blood gases in the newborn.

Continuous monitoring methods have shown changes of oxygenation in neonates during various procedures. However, actual changes in blood gases during vascular punctures have not been reported. We studied the effect of vascular puncture on arterial blood gases during routine venipuncture in 17 neonates who had indwelling arterial catheters. Arterial blood gases were analyzed before, during, and following recovery from venipuncture. Ventilator settings were not changed during the study, though oxygen concentration (FiO2) was adjusted as indicated by continuous PO2 or saturation monitors. During venipuncture, there was a significant fall in PaCO2 from 38 +/- 5 to 32 +/- 7 mmHg (P less than 0.0001) and in PaO2 from 75 +/- 21 to 58 +/- 23 mmHg (P less than 0.0001). Following venipuncture, both values returned to baseline. The results of this study imply that blood gases obtained by intermittent arterial sticks may provide data that do not accurately reflect the neonates' respiratory status.

Blood Gas Monitoring, Transcutaneous↗
PubMed1989

Long-term status of children treated for tuberculous meningitis in south India.

This report gives the findings of long-term follow-up (4 1/2-8 years) of 119 children who recovered from tuberculous meningitis. Of these, 17 patients died (10 due to severe tuberculous meningitis sequelae and 7 due to non-tuberculous causes) and 2 could not be traced. Of the remaining 100 patients for whom information was available, 47 (47%) made a complete recovery, while 53 (53%) had neurological sequelae--2 (2%) had severe, 39 (39%) moderate and 12 (12%) mild sequelae. There were no relapses during the 4 1/2-8 year period, indicating that regular treatment for 12 months may be adequate.

Antitubercular Agents↗
PubMed1986

Prognostic assessment of various parameters in chronic myeloid leukemia.

In 152 cases of chronic myeloid leukemia (CML) (actuarial median survival [MS], 59.2 months), the statistical relation of individual parameters with survival was studied to ascertain their prognostic value. The following parameters were found to be unrelated to the survival: age, sex, duration of symptoms, sternal bone tenderness, degree of hepatomegaly, level of hemoglobin, and leukocyte and platelet counts at the time of diagnosis. Splenomegaly of less than 10 cm and duration of first remission of 6 months or more were associated with significantly longer survival (MS, 70.5 and 68.5 months, respectively) as compared to bigger spleen size and duration of remission of less than 6 months (MS, 50.5 and 26 months; P less than 0.01 and P less than 0.05, respectively). The most significant prognostic parameter was the time required to achieve first remission. MS was 70 months in patients who achieved first remission in 2 months or less; it was 23.5 months in the remaining patients. This difference was statistically highly significant (P less than 0.001).

Adolescent↗
PubMed1986

Hepatic toxicity in South Indian patients during treatment of tuberculosis with short-course regimens containing isoniazid, rifampicin and pyrazinamide.

Results are presented of the incidence of hepatitis, nearly always with jaundice, among 1686 patients in clinical trials of the treatment of spinal tuberculosis, of tuberculosis meningitis and of pulmonary tuberculosis with short-course regimens containing rifampicin, isoniazid, streptomycin and pyrazinamide. The incidence was high in patients treated with daily regimens of isoniazid and rifampicin: 16-39% in children with tuberculous meningitis, 10% in patients with spinal tuberculosis (non-surgical cases), and 2-8% in those with pulmonary tuberculosis. Hepatitis, in those receiving rifampicin occurred more often in slow than in rapid acetylators of isoniazid, the proportions amongst those whose acetylator phenotype had been determined being 11% of 317 slow acetylators and 1% of 244 rapid acetylators. In children with tuberculous meningitis, the risk of hepatitis with isoniazid 20 mg/kg (39%) was higher than that with 12 mg/kg (16%), and appreciably lower in patients given rifampicin twice-weekly (5%) rather than daily (21%). There was no indication that pyrazinamide contributed to the hepatic toxicity.

Adolescent↗
PubMed1986

Three chemotherapy studies of tuberculous meningitis in children.

Chemotherapy studies were undertaken in 180 patients with tuberculous meningitis. They were treated for 12 months with 1 of 3 regimens: the first consisted of streptomycin, isoniazid and rifampicin daily for the first 2 months, followed by ethambutol plus isoniazid for 10 months; in the second, pyrazinamide was added for the first 2 months, and in the third, rifampicin was reduced to twice weekly in the first 2 months. Steroids were prescribed for all the patients in the initial weeks of treatment. Approximately 50% of the patients were aged less than 3 years. On admission, 13% of the patients were classified as stage I, 77% as stage II and 9% as stage III. Cerebrospinal fluid (CSF) culture results were available for all the 180 patients and M. tuberculosis was isolated in 59 (33%). CSF smear results for acid fast bacilli were available only for the 103 patients admitted to the second and the third studies, and of these in 60 (58%) the CSF was positive either by smear or culture. The response to therapy was similar in the 3 studies. Despite administration of rifampicin for 2 months, the mortality was high. In all, 27% of the patients died of tuberculous meningitis, 39% had neurological sequelae and 34% recovered completely. There was a strong association between the stage on admission and the mortality rate, the deaths being highest in stage III. In the first study, when isoniazid was prescribed daily in a dosage of 20 mg/kg, 39% of the patients developed jaundice; however, when the dosage was reduced to 12 mg/kg, the incidence fell to 16%. In the third study, where rifampicin was administered twice a week, the incidence of jaundice was much lower (5%).

Antitubercular Agents↗