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Biomedical subjects

R Nair

Publications and source records attributed to R Nair.

At least 109 records · Page 6Linked to original sources
PubMed1992

Amplification and overexpression of epidermal growth factor receptor gene in human oropharyngeal cancer.

The presence of epidermal growth factor receptor (EGF-R) gene was determined in 84 patients with squamous cell carcinoma (SCC) of the oropharyngeal region--a highly prevalent, chewing-tobacco associated malignancy in India, using Southern hybridisation analysis of DNA extracted from primary tumor tissues. We observed a 3- to 8-fold amplification of EGF-R gene in 19/66 (29%) of the SCCs of the oral cavity, and about 30-fold EGF-R amplification in 2/18 (11%) hypopharyngeal cancers. Dot blot analysis of total RNA from several tumour tissues, revealed overexpression of the EGF-R gene in the examined patients, with the EGF-R gene amplified. 4 patients with single copy EGF-R gene, did not exhibit overexpression of the gene. Within our sample set, no correlation was evident between EGF-R gene amplification and clinico-pathological parameters of the malignancy. The amplification and overexpression of the EGF-R gene observed in the primary tumour tissues of 25% (21/84) of the human oropharyngeal cancers, indicate possible involvement of the gene in the pathogenesis of these cancers.

Adult↗
PubMed1992

Thrombotic thrombocytopenic purpura: outcome in 24 patients with renal impairment treated with plasma exchange. Canadian Apheresis Study Group.

The Canadian Apheresis Study Group recently completed a randomized clinical trial involving 102 patients with thrombotic thrombocytopenic purpura (TTP), in which treatment with plasma infusion and treatment with plasma exchange were compared. Thirty-three other patients were ineligible or refused to be randomly assigned in the trial. Of the 33 patients, 24 were assessed as ineligible because they would be unable to tolerate the fluid input that would occur if they were randomly assigned to receive plasma infusion. All 24 patients had oliguria and elevated creatinine and/or blood urea nitrogen level. These 24 patients were treated with acetylsalicyclic acid, dipyridamole, and plasma exchange according to the standardized protocol defined in the trial. Blood for tests of factors possibly involved in the pathogenesis of TTP was drawn before exchange and at intervals during and after exchange. The mean platelet count before exchange was 35.5 x 10(9) per L. In 12 of the 24 patients, the platelet count reached 150 x 10(9) per L or greater by 7 days after the initiation of plasma exchange. Three patients responded partially, in that their platelet count increased to at least twice that at presentation, but remained below 150 x 10(9) per L. One patient died during the first week. Of the eight other patients who experienced treatment failure at the 7-day assessment point, six subsequently responded, four while continuing to receive plasma exchange and two after plasma exchange had been discontinued. Of the 15 patients who either responded fully or responded partially by the end of the first cycle, all survived.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Anomalous septal perforator artery: a source for supportive circulation in severe coronary artery disease--case reports.

Anomalous origin of a septal perforator artery is an infrequent angiographic finding. However, its recognition is important in patients with coronary artery disease in order to avoid misdiagnosis and consequent management mistake. In 2 patients, coronary arteriography demonstrated an anomalous septal perforator artery supplying significant blood flow to a myocardial region previously perfused by a severely obstructed major coronary vessel. It appears that an anomalous septal artery can serve as an important source for supportive circulation in severe coronary artery disease.

Aged↗
PubMed1992

Laparoscopic gastrointestinal surgery.

The growth and scope of laparoscopic gastrointestinal surgery are outstripping the ability of medical journals to print series and reports of experience, and much data remain anectodal and preliminary. Laparoscopic cholecystectomy has become established, although, unfortunately, peroperative cholangiography has not yet become normal practice, despite convincing published evidence that it is likely to reduce the increased number of bile ducts that are damaged by laparoscopic surgeons. Imaging the bile ducts and the overall management of choledocholithiasis need re-evaluation, and the approach will change as more surgeons explore the bile ducts laparoscopically. Laparoscopic hiatal anti-reflux surgery will soon be routine, and a whole range of laparoscopically assisted operations on the oesophagus, colon, and rectum will become commonplace. Operations on the liver remain anecdotal. Throughout this rapid progress, surgeons must not forget the principles of (open) surgical practice, whilst carefully kept registers and regular audit of operations will provide new surgical standards.

Cholecystectomy, Laparoscopic↗
PubMed1991

Chronic myelomonocytic leukaemia (an analysis of fourteen consecutive cases).

Fourteen consecutive cases of chronic myelomonocytic leukaemia aged 6 to 73 (mean 40.5) years were reviewed to define the natural history of the disease and the risk of acute transformation. The common presenting features included anaemia, fever, purpura, and bleeding tendencies. Abnormal karyotypes were seen in 4 of 6 patients subjected to cytogenetic analysis. Low dose cytosine arabinoside achieved complete remission in two and partial remission in one, of the four patients treated with this modality. The mean survival was 5.6 (range 2-12) months and two patients) evolved to acute myeloid leukaemia. The long term survival with the present form of therapy in chronic myelomonocytic leukaemia is poor.

Adolescent↗
PubMed1990

Restriction fragment length polymorphism of the L-myc gene in oral cancer patients.

Restriction fragment length polymorphism (RFLP) of the L-myc gene was examined in DNAs from primary tumour tissues and peripheral blood cells (PBC) of 76 Indian patients with squamous cell carcinoma of the oral cavity, and PBC from 101 normal healthy volunteers. The patients and the normal healthy volunteers were classified into three genetic types according to the polymorphic patterns defined by the two alleles (6.6 kb, S fragment; and 10.0 kb, L fragment). DNA isolated from the PBC of each patient always exhibited the same pattern of L-myc alleles as that observed for the corresponding tumour DNA. However, a striking correlation was found between the RFLP pattern and the stage of differentiation of the tumours, as well as the size of the tumour. Thus, a preponderance of the S fragment was observed in the poor to moderately differentiated tumours and the larger (greater than 4 cm) sized tumours. Further, analysis of L-myc RFLP with the clinical pattern of the malignancy showed no significant correlation with nodal metastasis, TNM staging or recurrence of the tumour. The relative ratios of the three genotypes (L-L, L-S, S-S) in the oral cancer patients were not significantly different from those seen in the healthy Indians, implying no predisposition to oral cancer by either allele. However, our results showed that oral cancer patients with a genotype including an S fragment are more likely to develop a poor to moderately differentiated tumour or a larger tumour than a patient without an S fragment. The L and S alleles were equally distributed in the population, with the frequency of each allele being 0.50, consistent with Hardy-Weinberg's law.

Adult↗
PubMed1989

Elucidation of the nifedipine-quinidine interaction.

Four case reports have been published that document a clinically significant drug interaction between nifedipine and quinidine in patients with left ventricular dysfunction. To define the population at risk and the mechanisms involved in manifestations of this interaction, 12 patients currently treated with quinidine for either ventricular or supraventricular arrhythmias were stratified into two groups based on left ventricular ejection fraction (EF) measurements (group A greater than 35%; group B less than 35%). The interaction was conducted through two phases: oral quinidine (Q) and oral quinidine plus nifedipine (N + Q). Pharmacokinetic modeling of total body clearance (CL) and AUC were assessed for each phase. One patient (group A, 70% EF) exhibited the interaction with a 41% decrease in steady-state serum quinidine concentrations. The patient's AUC and CL were 48.2 micrograms/ml.hr (Q) versus 28.6 micrograms/ml.hr (N + Q) and 94.4 ml/min (Q) versus 159.1 ml/min (N + Q), respectively. There was no difference in AUC or CL between the Q and N + Q phases or between groups A and B for the entire population. The N + Q interaction is not hemodynamically mediated. Clinical consideration of the possibility of this low-frequency interaction should be noted.

Adult↗
PubMed1989

Oncogene amplification in squamous cell carcinoma of the oral cavity.

We have determined the prevalence of amplification of c-myc, N-myc, L-myc, H-ras, Ki-ras, and N-ras oncogenes in 23 cases of squamous cell carcinoma of the oral cavity, using Southern hybridization analysis of DNA extracted from the primary tumor tissues. Nick-translated oncogene probes and oncogene inserts labeled to high specific activities were used. We observed a 5- to 10-fold amplification of one or more of c-myc, N-myc, Ki-ras and N-ras oncogenes in 56% of the tumor tissue samples, with these oncogenes not being amplified in the peripheral blood cells of the same patients. L-myc and H-ras were not amplified in any of our samples. The oncogene amplifications seemed to be associated with advanced stages of squamous cell carcinomas, with the ras and myc family oncogenes being amplified in stages 3 and 4. Hybridization with N-myc detected an additional 2.3 kb EcoRI fragment, along with the normal 2.1 kb fragment. Our data also demonstrated amplification of multiple oncogenes in the same tumor tissue sample. About 60% of the samples with amplified oncogenes showed simultaneous amplification of 2 or more oncogenes. The results showing different oncogene amplifications in similar tumors, as well as multiple oncogene amplifications in the same tumor, suggest that these oncogenes may be alternatively or simultaneously activated in oral carcinogenesis.

Adult↗
PubMed1988

Does parasternal irradiation reduce thoracic vertebral metastases in breast cancer?

A review of 197 patients with bone metastases from breast carcinoma was undertaken to assess the effect of adjuvant parasternal irradiation on the distribution of those metastases. A total of 128 patients (Group I) received radiation. The control group consisted of 69 patients (Group II) who did not receive adjuvant radiation. The dose absorbed by the mid-thoracic vertebrae (T3 to T8) varied from 10 Gy in 3 weeks to 20 Gy in 4 weeks. The distribution of bone metastases was analyzed at the initial development in the 197 patients. Repeat assessments (X ray/scans) were available for analysis in 132 patients. Patients in Group I had less metastases from T3 to T8: 37/128 (29%), vs 30/69 (43.5%) for patients in Group II: (chi 2 = 3.62; p less than 0.10). For the 132 patients with serial assessments, the difference at last evaluation was more significant: 45/86 (52%) in Group I, vs 36/46 (78%) in Group II: (chi 2 = 7.44; p less than 0.01). The data shows that patients receiving low-dose exit beam irradiation from the parasternal field have fewer mid-thoracic bone metastases. Potential implications are discussed.

Breast Neoplasms↗
PubMed1987

Change in composition of high density lipoprotein during gemfibrozil therapy.

We investigated the high density lipoprotein cholesterol (HDL-C) response in 20 middle-aged males during a 12-week course of gemfibrozil. Three aspects of the increase in HDL-C (25%) were studied and our observations are as follows: (1) subfraction analysis showed that HDL3-C rose earlier and to a larger extent (28%) than HDL2-C (15%), (2) analysis of variance group--time interaction effect and correlation studies of HDL-C and total triglycerides suggest the increase in HDL-C was due to a direct effect of gemfibrozil on HDL metabolism, and (3) HDL-C was the only one of 4 HDL components to increase. Apoprotein A-I (apo A-I) and HDL-phospholipid (HDL-PL) did not change, and HDL-triglyceride (HDL-TG) decreased. This pattern is consistent with a change in composition of HDL, i.e. cholesterol enrichment and triglyceride depletion.

Adult↗
PubMed1987

Regulation of cell-mediated immunity in mice immunised with Salmonella enteritidis.

The effects of diverse factors, such as route of immunisation, composition of immunogen and administration of interferon inducer, on the expression of cell-mediated immune responses against Salmonella enteritidis were investigated in BALB/c and Swiss white mice. Immunisation with live cells of S. enteritidis by the intraperitoneal route (ip) generated both delayed type hypersensitivity (DTH) and protective cell-mediated immunity (CMI). However, the two responses showed diametrically opposite time kinetics. The decline and disappearance by 9 weeks after ip immunisation of DTH and the rise of protective immunity in the same period suggested the possibility that the two responses were mediated by different subsets of T cells. Immunisation by the intradermal (id) route with a sonicate of S. enteritidis generated only DTH; id immunisation also suppressed the development of the protective response following ip immunisation with live S. enteritidis. Both responses were not seen when T cells were eliminated with anti-T cell serum. Oral immunisation with live cells of S. enteritidis induced excellent CMI expressing both DTH and protective responses. On the other hand, oral immunisation with the sonicate of S. enteritidis not only did not induce CMI, but also prevented the development of the DTH and protective response to ip immunisation with live S. enteritidis. Induction of interferon by the administration of poly I: poly C for four consecutive days after id immunisation with killed S. enteritidis suppressed the generation of DTH.

Animals↗
PubMed1986

Prevalence of speech and language disorders in 5-year-old kindergarten children in the Ottawa-Carleton region.

A representative sample of 5-year-old kindergarten children was assessed for speech and/or language disorder. Of the 1,655 children tested, 180 were identified as having speech or language impairment. It is estimated that within the total reference population, between 16.2% and 21.8% would show some impairment; for the boys, the rate would be 15.5% to 20.7% and for the girls, between 19.1% and 25.1%. Most of these children would show some language impairment as opposed to speech problems only. Approximately 36% of the identified boys and 30% of the girls would have speech problems only, the remainder having speech and language problems or language problems only. Followup studies of these children are needed to ascertain their outcome and language status in middle childhood.

Articulation Disorders↗
PubMed1986

The effect of dietary polyunsaturated fat on cation transport and hypertension in the rat.

1. Essential hypertension is associated with increased intracellular sodium in both erythrocytes and leucocytes. Reports in the literature indicate that increasing the level of polyunsaturated fat in the diet reduces hypertension. In the present study, spontaneously hypertensive rats (Wistar-Kyoto, which develop systolic blood pressures in excess of 140 mmHg by 8 weeks of age) were fed on high-fat diets (40% energy derived from fat), the fat being maize oil (high in polyunsaturated fatty acids, PUFA) and coconut oil (low in PUFA). 2. Significantly higher blood pressures developed by 110 d of age in the rats fed on a high-PUFA diet, compared with those fed on the low-PUFA diet. 3. In thymocytes, ouabain-sensitive efflux rate constants were significantly lower in the group fed on the high-PUFA diet. Ouabain-insensitive efflux rate constants were unaffected by diet.

Animals↗