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Biomedical subjects

P Subramaniam

Publications and source records attributed to P Subramaniam.

At least 19 recordsLinked to original sources
PubMed2006

An in vitro evaluation of pH variations in calcium hydroxide liners.

The purpose of this present study was to determine the pH changes of five different commercially available calcium hydroxide liners and variations of pH at different time intervals. The following commercially available materials were investigated: Dycal (LD Caulk); Calcimol (Vocco Products); calcium hydroxide powder (Deepti Products); Calcimol LC (Vocco Products); Lime-Lite (Pulpdent Corporation). Five samples were prepared from each liner. The pH measurements were recorded at time intervals of 1 h, 24 h, 3 days and 7 days after mixing of the liner. The pH variations of each material at the given time intervals were recorded and the means were calculated. Comparison of the mean values at all time intervals with the statistical analysis showed significantly high differences (P < 0.001) between pH values induced by each material at all time intervals. Among the water-insoluble products, Dycal had the strongest alkaline effect after 7 days interval. The materials that chemically hardened produced higher pH values than materials that hardened by a visible light source after 7 days.

Analysis of Variance↗
PubMed2005

Prophylactic nasal continuous positive airways pressure for preventing morbidity and mortality in very preterm infants.

BACKGROUND: Cohort studies (Avery 1987; Jonsson 1997) have suggested that early post-natal nasal continuous positive airways pressure (CPAP) may be beneficial in reducing the need for intubation and intermittent positive pressure ventilation, and in preventing chronic lung disease in preterm or low birth weight infants. OBJECTIVES: To determine if prophylactic nasal CPAP commenced soon after birth regardless of respiratory status in the very preterm or very low birth weight infant reduces the use of IPPV and the incidence of chronic lung disease (CLD) without adverse effects. SEARCH STRATEGY: The search was updated in April 2005. The standard search strategy of the Neonatal Review Group was used. This included searches of the Oxford Database of Perinatal Trials, Cochrane Library Issue 1 2005, MEDLINE 1966-April 2005, previous reviews including cross references, abstracts, conferences, symposia, proceedings, expert informants, journal hand searching mainly in the English language. SELECTION CRITERIA: All trials using random or quasi-random patient allocation of very preterm infants < 32 weeks gestation and / or < 1500 gms at birth were eligible. Comparison had to be between prophylactic nasal CPAP commencing soon after birth regardless of the respiratory status of the infant compared with "standard" methods of treatment where CPAP or IPPV is used for a defined respiratory condition. DATA COLLECTION AND ANALYSIS: Standard methods of the Cochrane Collaboration and its Neonatal Review Group, including independent assessment of trial quality and extraction of data by each author, were used. Data were analysed using relative risk (RR). Meta-analysis was performed using a fixed effects model. MAIN RESULTS: There are no statistically significant differences in any of the outcomes studied in either of the eligible trials (Han 1987; Sandri 2004) reporting on 82 and 230 infants respectively. In Han 1987 there are trends towards increases in the incidence of BPD at 28 days [RR 2.27 (0.77, 6.65)], death [RR 3.63 (0.42, 31.08)] and any IVH [RR 2.18 (0.84, 5.62)] in the CPAP group. In Sandri 2004 there is a trend towards an increase in IVH grade 3 or 4 [RR 3.0 (0.96, 28.42)] in the CPAP group. No outcome was significantly different in any of the meta-analyses. AUTHORS' CONCLUSIONS: There is currently insufficient information to evaluate the effectiveness of prophylactic nasal CPAP in very preterm infants. Neither of the included studies reviewed showed evidence of benefit in reducing the use of IPPV. The tendency for some adverse outcomes to be increased is of concern and further multicentre randomized controlled trials are needed to clarify this.

Chronic Disease↗
PubMed2005

An in vitro comparison of root canal measurement in primary teeth.

To compare the accuracy of root canal lengths in primary teeth determined by tactile sense, electronic apex locator, conventional radiography, and digital radiography in primary teeth. The study sample consisted of twenty 20 extracted, single-rooted primary teeth. A comparison was made between the working length measurements obtained by tactile sensation, electronic apex locator, conventional film, and digital radiography, using stereomicroscopic measurements to obtain real canal length. The mean readings obtained were 15.91+/-2.06 by tactile measurement, 15.94 94+/-1.42 by apex locator, 16.06+/-1.73 by conventional radiography, and 15.91+/-1.60 by digital radiography. No statistically significant differences were seen between the techniques.

Dental Pulp Cavity↗
PubMed2001

Effect of calcium channel blockers on proteoglycan synthesis by vascular smooth muscle cells and low density lipoprotein--proteoglycan interaction.

Calcium channel blockers are known to retard atherosclerosis. In this study, we tested the hypothesis that one mechanism by which calcium channel blockers retard atherosclerosis is through the modulation of proteoglycan metabolism by vascular smooth muscle cells. We investigated the effect of amlodipine and nifedipine on proteoglycan synthesis by human aortic smooth muscle cells and the ability of the newly synthesized proteoglycans to bind low density lipoprotein (LDL). Confluent smooth muscle cells were incubated with [(35)S]sulfate alone or [(35)S]sulfate and [(3)H]leucine in the presence and absence of different concentrations of amlodipine and nifedipine (0.1--20 microg/ml) for 24 h, and newly synthesized proteoglycans were analyzed. Both amlodipine and nifedipine inhibited proteoglycan synthesis by smooth muscle cells in a dose-dependent manner; however, amlodipine was significantly more potent than nifedipine in this regard. In the presence of 20 microg/ml amlodipine, media and cellular proteoglycans decreased by 56%. This was due to inhibition of de novo proteoglycan synthesis by amlodipine. Compared with the proteoglycans synthesized by control smooth muscle cells, those synthesized by cells exposed to amlodipine were smaller and less sulfated, and contained fewer glycosaminoglycan chains. In addition, proteoglycans synthesized by cells treated with amlodipine bound LDL with low affinity. These results suggest that amlodipine may protect against atherosclerosis through a proteoglycan-mediated mechanism.

Amlodipine↗
PubMed2001

Bovine interferon-tau stimulates the Janus kinase-signal transducer and activator of transcription pathway in bovine endometrial epithelial cells.

Trophoblastic bovine interferon-tau (bIFN-tau) suppresses luteolytic pulses of endometrial prostaglandin F(2alpha) (PGF(2alpha)) at the time of maternal recognition of pregnancy. This results in maintenance of the corpus luteum in cattle. The hypothesis that effects of bIFN-tau in the endometrium were through activation of the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway of signal transduction was tested. Whole cell, cytosolic, and nuclear extracts from bovine endometrial cells treated with bIFN-tau were analyzed by immunoprecipitation, immunoblotting, and electrophoretic mobility shift assays in a series of dose- and time-dependency experiments. Bovine IFN-tau stimulated tyrosine phosphorylation, homo- and heterodimer formation, nuclear translocation, and DNA binding of STAT proteins 1, 2, and 3. Moreover, bIFN-tau induced synthesis of interferon-regulatory factor. In conclusion, bIFN-tau stimulates the JAK-STAT pathway in the bovine endometrium. It is proposed that activation of the JAK-STAT pathway is involved in regulating the antiluteolytic effects of bIFN-tau.

Animals↗
PubMed2001

The prevalence and pattern of wife beating in the Trincomalee district in eastern Sri Lanka.

A descriptive cross-sectional study was carried out to determine the prevalence and to identify some socio-demographic factors associated with wife beating in the Medical Officer of Health (MOH) area of Kantale in the Trincomalee district of eastern Sri Lanka. A random sample of 417 women in the age category 18-49 years constituted the sample population. Data were obtained by focus group discussions followed by the administration of a structured questionnaire by trained interviewers. The prevalence of reported wife beating among ever-married women was 30% and the prevalence of wife beating in the year preceding the study was 22%. There was no significant association between wife beating and ethnicity of the study population or a particular age group of either the batterer or the victim. Moreover, wife beating was associated with an early age at marriage for women, low-income, a low standard of living index, large families and alcohol consumption by the batterer. A significant inverse relationship between domestic violence and the level of education of both the batterer and the victim was also identified. Contusions, typically distributed in the region of the head, face and neck were found to be the commonest type of injury suffered by battered women. A majority of women, irrespective of their level of education and employment status placed the welfare of their children as the prime reason for continuing to stay in an abusive relationship. The study concludes that wife beating is a serious health and social problem for the women population of Kantale. Intervention is recommended in relation to key issues identified by the study, including alcohol abuse by men, relative lack of education among the population, lack of family planning, societal influences promoting teenage marriages of the girl-child and absence of programs aimed at creating awareness on wife beating.

Adult↗
PubMed2000

Continuous positive airway pressure versus theophylline for apnea in preterm infants.

BACKGROUND: Recurrent apnea is common in preterm infants, particularly at very early gestational ages. These episodes of loss of effective breathing can lead to hypoxemia and bradycardia which may be severe enough to require resuscitation including use of positive pressure ventilation. Theophylline stimulation of breathing and continuous positive airways pressure have been used to prevent apnea and its consequences. OBJECTIVES: The main objective was to determine in preterm infants with recurrent apnea, if treatment with CPAP compared with treatment with theophylline leads to a clinically important reduction in apnea or use of mechanical ventilation, without clinically important side effects. SEARCH STRATEGY: The standard search strategy of the Neonatal Review Group was used. This includes searches of the Oxford Database of Perinatal Trials, Cochrane Controlled Trials Register, MEDLINE, previous reviews including cross references, abstracts, conferences, symposia proceedings, expert informants and journal hand searching mainly in the English language. SELECTION CRITERIA: All trials using random or quasi-random allocation to CPAP or theophylline in preterm infants with clinical recurrent apnea/bradycardia were eligible. DATA COLLECTION AND ANALYSIS: Data were extracted using standard methods of the Cochrane Collaboration and its Neonatal Review Group, with separate evaluation of trial quality and data extraction by each author and synthesis of data using relative risk. MAIN RESULTS: The use of mask CPAP is associated with a higher treatment failure rate as measured by less than a 50% reduction in apnea or use of the alternative treatment [RR 2.89 (95% CI 1.12,7.47); RD 0.42 (95% CI 0. 11, 0.74)]. For every 2.4 infants (95% CI 1.4, 9.5) treated with mask CPAP rather than theophylline, there results one treatment failure. In the mask CPAP group there is more use of IPPV [RR 3.09 (1.42,6.70; RD 0.58 (95% CI 0.30, 0.86). For every 1.7 infants (95% CI 1.2, 3.3) treated with mask CPAP rather than theophylline, one infant is intubated for IPPV. In the mask CPAP group, there are trends towards more deaths in the first year, and in death or major disability in survivors at follow up, which do not reach significance. There are no differences in rates of necrotizing enterocolitis or major disability in survivors at follow up. REVIEWER'S CONCLUSIONS: Theophylline is more effective than mask CPAP for preterm infants with apnea. Since CPAP is no longer administered by mask, the results of this review have limited importance for current clinical practice. Further evaluation of the benefits and harms of CPAP vs theophylline for preterm infants with apnea requires further trials in which CPAP is administered by current methods.

Apnea↗
PubMed2000

Prophylactic nasal continuous positive airways pressure for preventing morbidity and mortality in very preterm infants.

BACKGROUND: This section is under preparation and will be included in the next issue. OBJECTIVES: To determine if prophylactic nasal continuous positive airways pressure (CPAP) commenced soon after birth regardless of respiratory status in the very preterm or very low birth weight infant reduces the use of IPPV and the incidence of chronic lung disease (CLD) without adverse effects. SEARCH STRATEGY: The standard search strategy of the Neonatal Review Group was used. This included searches of the Oxford Database of Perinatal Trials, Cochrane Controlled Trials Register, MEDLINE, previous reviews including cross references, abstracts, conferences, symposia, proceedings, expert informants, journal hand searching mainly in the English language. SELECTION CRITERIA: All trials using random or quasi-random patient allocation of very preterm infants < 32weeks gestation and / or < 1500 gms at birth were eligible. Comparison had to be between prophylactic nasal CPAP commencing soon after birth regardless of the respiratory status of the infant compared with "standard" methods of treatment where CPAP or IPPV is used for a defined respiratory condition. DATA COLLECTION AND ANALYSIS: Standard methods of the Cochrane Collaboration and its Neonatal Review Group, including independent assessment of trial quality and extraction of data by each author, were used. Data were analysed using relative risk (RR). MAIN RESULTS: There are no statistically significant differences in any of the outcomes reported in the single eligible study of 82 very low birth weight infants. More infants in the prophylactic nasal CPAP group received IPPV; however, this difference is not statistically significant. There are trends towards increases in the incidence of CLD (undefined) [RR 2.27 (0.77, 6.65)], of death [RR 3.63 (0.42, 31.08)] and of intraventricular hemorrhage [RR 2.18 (0.84, 5.62)] in the treatment group. The study also found a trend towards a reduction in the incidence of necrotizing enterocolitis in the treatment group [RR 0.40 (0.13, 1.21)]. REVIEWER'S CONCLUSIONS: There is currently insufficient information to make recommendations for clinical practice. The single study reviewed showed no strong evidence of benefit in reducing the incidence of IPPV. The tendency for some adverse outcomes to be increased is of concern and more data are needed to clarify this. A multicentre randomized controlled trial comparing prophylactic nasal CPAP with "standard" methods of treatment is needed to clarify its clinical role.

Chronic Disease↗
PubMed2000

Continuous distending airway pressure for respiratory distress syndrome in preterm infants.

BACKGROUND: Respiratory distress syndrome (RDS) is the single most important cause of morbidity and mortality in preterm infants (Greenough 1998, Bancalari 1992). Intermittent positive pressure ventilation (IPPV) with surfactant is the standard treatment for the condition. The major difficulty with IPPV is that it is invasive, resulting in airway and lung injury and contributing to the development of chronic lung disease. OBJECTIVES: In spontaneously breathing preterm infants with RDS, to determine if continuous distending airway pressure (CDAP) reduces the need for IPPV and associated morbidity without adverse effects. SEARCH STRATEGY: The standard search strategy of the Neonatal Review group was used. This included searches of the Oxford Database of Perinatal Trials, Cochrane Controlled Trials Register, MEDLINE, previous reviews including cross references, abstracts, conference and symposia proceedings, expert informants, journal hand searching mainly in the English language. SELECTION CRITERIA: All trials using random or quasi-random patient allocation of newborn infants with RDS were eligible. Interventions were continuous distending airway pressure including continuous positive airway pressure (CPAP) by mask, nasal prong, nasopharnygeal tube, or endotracheal tube, or continuous negative pressure (CNDP) via a chamber enclosing the thorax and lower body, compared with standard care. DATA COLLECTION AND ANALYSIS: Standard methods of the Cochrane Collaboration and its Neonatal Review Group, including independent assessment of trial quality and extraction of data by each author, were used. MAIN RESULTS: CDAP is associated with a lower rate of failed treatment (death or use of assisted ventilation), overall mortality, and mortality in infants with birthweights above 1500 g. The use of CDAP is associated with an increased rate of pneumothorax. REVIEWER'S CONCLUSIONS: In preterm infants with RDS the application of CDAP either as CPAP or CNDP is associated with some benefits, particularly in infants with birthweights over 1500 gms. The extent of this benefit is difficult to assess given the outdated methods to administer CDAP, low use of antenatal corticosteroids, non-availability of surfactant and the intensive care setting of the 1970's in which these trials were done. Where resources are limited, such as in developing countries, CPAP for RDS may have a clinical role. Further research is required to determine the best mode of administration and its role in modern intensive care settings

Humans↗
PubMed1999

Serial echocardiographic and clinical evaluation of valvular regurgitation before, during, and after treatment with fenfluramine or dexfenfluramine and mazindol or phentermine.

OBJECTIVE: The prevalence of cardiac valvular regurgitation demonstrated by echocardiography in patients who took appetite-suppressant medication for weight loss has been assessed at 5%-30%. We studied 86 patients who had echocardiograms before treatment with appetite suppressants to determine the incidence of new cases and to evaluate the clinical implication of the echocardiographic findings. RESEARCH METHODS AND PROCEDURES: We studied 69 men [Mean+/-Standard Deviation (S) age 49+/-8] and 17 women (mean+/-S age 50+/-7) who had 233 echocardiograms before, during, and after a weight-loss program that used predominantly fenfluramine (or dexfenfluramine) with mazindol (or phentermine). Mean drug exposure was 17 months. Blinded echocardiographic readings were performed to identify and grade aortic regurgitation (AR) or mitral regurgitation (MR). RESULTS: Seven of 86 patients (8%) had pre-existing regurgitation with five (6%) meeting our case definition. Thirteen (16.5%) of initially normal patients developed valvular regurgitation and were new cases. Of the new cases, 12 were grade I/IV AR and one was both grade II/III MR and II/IV AR. All 13 patients were asymptomatic, and only two aortic insufficiency murmurs could be auscultated. There was significantly greater risk for developing valvulopathy for those who took medications longer than 6 months (p = 0.03), and no new cases were observed in patients exposed for less than 8 months. No increased risk associated with age, presence of hypertension, or exposure to fenfluramine-phentermine combination was demonstrated. Although there was a higher incidence of new regurgitation in women (31% vs. 13% for men), this was not statistically significant (p = 0.093). DISCUSSION: Some patients who had normal echocardiograms at baseline developed cardiac valvular regurgitation after exposure to fenfluramine or dexfenfluramine with mazindol or phentermine. The development of valvulopathy was significantly correlated with duration of exposure. The clinical implications of echocardiographically demonstrated regurgitation are uncertain, since there were only two audible murmurs and no other clinically relevant signs or symptoms among the patients.

Aortic Valve Insufficiency↗
PubMed1998

Infrarenal aortic aneurysm surgery in a rural surgical service: risk factors for mortality.

BACKGROUND: An audit of both the emergency and elective abdominal aortic surgery that was performed in a rural surgical service, was carried out. METHODS: Retrospective data analysis was performed on 41 patients who were treated for abdominal aortic aneurysms (AAA) during an 8-year period from 1989 to 1996. Postoperative outcomes were analysed with respect to patient age, mode of presentation (elective or emergency), transfusion requirements and pre-existing cardiac and respiratory disease. Univariate analysis was performed using Fisher's exact test, and the odds ratio for adverse outcome was calculated. RESULTS: A postoperative mortality rate of 5.8% in elective repairs and 68% in cases of rupture was noted. Pre-existing respiratory disease, transfusion requirements of more than six units and presentation with retroperitoneal leak or rupture correlated with postoperative mortality, while age and pre-existing cardiac disease were shown not to be predictive of adverse outcome following surgery. CONCLUSIONS: An overall improvement in operative outcomes in the institution (Wimmera Base Hospital) that was audited would be affected by earlier referral for elective repair in selected patients. Like others, the authors believe that age on its own is not a contraindication to elective AAA repair.

Aged↗
PubMed1998

Inguinal hernia repair: a comparison between local and general anaesthesia.

BACKGROUND: A comparative analysis of outcomes of inguinal hernia repair performed under local (LA) and general anaesthesia (GA) by a single surgeon using a standardized technique of anterior transversalis repair was performed. Ninety-three cases were examined, 56 of which were cases of LA hernia repair. METHODS: A retrospective analysis of the patient hospital record was performed with particular attention to intra-operative and post-operative analgesia requirements. RESULTS: An overall series complication rate of 6.5% (6/93) is reported. Only one of 56 LA patients (2%) required more than 24 h of narcotic analgesic injections compared to 11% (4/37) in the GA group (P < 0.05). The mean total postoperative parenteral narcotic requirement in the LA group was 86+/-14 mg of pethidine as compared to the GA group who had a mean total requirement of 121+/-17 mg of pethidine (P > 0.08). CONCLUSIONS: The LA infiltration technique is an effective method for inguinal hernia repair. This series demonstrates benefits in terms of length of hospital stay and a lower incidence of postoperative parenteral narcotic analgesic requirement although when post-operative parenteral narcotics were required by the LA group of patients, the difference in mean total pethidine requirement was not statistically significant.

Adult↗
PubMed1997

beta-Galactosidase reporter system in mycobacteria and its application in rapid antimycobacterial drug screening.

Pathogenic mycobacteria are generally slow growing organisms and it takes several weeks to evaluate inhibitors of growth. Therefore, for rapid screening of the inhibitors of mycobacterial growth, a beta-galactosidase reporter system has been described which utilises a recombinant Mycobacterium smegmatis mc(2)155 expressing E. coli lacZ gene as the test organism. The assay is based on production of beta-galactosidase in presence of drugs during growth. A correlation between beta-galactosidase production and colony forming ability of mycobacteria was obtained. beta-galactosidase production was inhibited within 6 h by front line standard antimycobacterial drugs like streptomycin, rifampicin, isoniazid, ethambutol, pyrazinamide and ofloxacin at their reported MICs. The assay was performed on mycobacterial cells permeabilized with chloroform and sodium dodecyl sulfate.

Anti-Bacterial Agents↗
PubMed1996

Acute aortic dissection as a complication of coronary artery surgery.

Acute dissection of the ascending aorta is a rare, potentially fatal complication of cardiac surgery. During surgery patients with long-standing hypertension and atheromatous arterial disease require careful handling and cannulation of the aorta and aggressive intra-operative and postoperative management of aortic pressure. We present the successful treatment of a patient with acute aortic dissection following elective coronary artery surgery.

Acute Disease↗
PubMed1996

Initial parathyroid exploration: current trends in Australia.

BACKGROUND: An Australia-wide multicentre prospective study was undertaken to audit cases of initial parathyroid exploration between 1 January and 31 December 1992. One hundred and sixty-two cases were audited. The audit was designed to study pre-operative biochemical assessment, localization techniques and the technique of exploration. METHOD: A pro forma audit form was circulated to all Australian surgeons known to perform parathyroid surgery. Eleven responded. RESULTS: Free serum ionized calcium (iCa) was measured in 30% of cases, with the majority of pre-operative calcium assays being performed using total serum calcium (tCa). In 40 cases (29%) pre-operative localization techniques were used. These proved inaccurate in 10 cases. The intra-operative technique of localization with methylene blue infusion was used in 11% of cases. All four glands were biopsied in 11% of cases. No deaths were reported and a postoperative morbidity rate of 3.1% was noted. Eighty-eight per cent of patients were discharged within 5 days of surgery with a third going home within 48 h of neck exploration surgery. Only one patient (0.6%) required re-exploration for persistent hypercalcaemia due to a second adenoma. CONCLUSIONS: The surgical treatment of hyperparathyroidism can be regarded as safe, with minimum morbidity in experienced hands. Pre-operative localization studies in initial parathyroid exploration are not indicated.

Adolescent↗
PubMed1996

P53 tumour suppressor gene expression in hyperparathyroidism.

BACKGROUND: Mutations of the p53 tumour suppressor gene lead to the loss of control of normal cellular proliferation and differentiation and have been shown to be associated with the development of malignancy. METHOD: Archival paraffin resection specimens from 86 cases of hyperparathyroidism treated surgically using the rabbit polyclonal CMI antibody were investigated to detect p53 immunoreactivity in these sections. RESULTS: Eighteen of the 86 sections examined (21%) showed nuclear immunoreactivity. No correlation was detected between tumour histology and p53 immunoreactivity (P = 0.45), nor was there any correlation between tumour clonality and immunoreactivity (P = 0.54). Multiple endocrine neoplasia type 1 (MEN 1) status did not correlate with p53 immunoreactivity. A significant correlation between p53 immunoreactivity and preparathyroidectomy calcium levels of > 1.5 mmol/L was detected (P < 0.005) although no correlation was noted between p53 immunoreactivity and higher levels of preparathyroidectomy intact parathyroid hormone (PTH) levels. CONCLUSION: A relationship is postulated between abnormal serum calcium regulation and p53 mutation in hypercalcaemic states associated with hyperparathyroidism.

Calcium↗
PubMed1995

Inactivation of retinoblastoma gene in malignant parathyroid growths: a candidate genetic trigger?

The molecular basis for parathyroid carcinoma remains undetermined. Parathyroid carcinoma potentially remains curable by early en bloc resection. This requires a reliable diagnostic tool as histological features alone are insufficient to distinguish parathyroid carcinoma from its benign counterpart, parathyroid adenoma. A variety of human cancers arise from the inactivation of the retinoblastoma (RB) gene, a tumour-suppressor gene on chromosome 13q14. We investigated the role of this gene in parathyroid growths by using a mouse monoclonal antibody to detect RB gene expression immunohistochemically. Two of the three parathyroid carcinomas in this study showed evidence of RB gene inactivation compared with one of 11 benign parathyroid entities. Three normal parathyroid glands stained showed strong evidence of RB gene expression in all three glands. The relationship between RB gene inactivation and parathyroid malignancy, however, was not statistically significant.

Animals↗