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Biomedical subjects

C Nair

Publications and source records attributed to C Nair.

At least 19 recordsLinked to original sources
PubMed2004

99Tc(m)(V)DMSA scintigraphy in skeletal metastases and superscans arising from various malignancies: diagnosis, treatment monitoring and therapeutic implications.

Skeletal metastases arising from a wide variety of malignancies including a few cases with superscan appearance were evaluated using (99)Tc(m) MDP bone scanning and (99)Tc(m)(V)DMSA scintigraphy. Whole body planar scans were obtained at 3 h and 24 h after injection of 740 MBq (99)Tc(m) MDP and 5 days later at similar times after injection of 555 MBq of (99)Tc(m)(V)DMSA. A qualitative as well as quantitative comparison was made between the (99)Tc(m) MDP bone scan and the (99)Tc(m)(V)DMSA scan in detection of osseous metastases. The reference methods used for discordant or equivocal lesions were correlative morphological imaging modalities, for example additional conventional radiography, CT or MRI. The present pictorial review deals with the results of qualitative analysis of the study. A total of 75 cases have been evaluated. The vignettes illustrated in the present article demonstrate avid (99)Tc(m)(V)DMSA concentration in skeletal metastases from a wide variety of malignancies and thus expand the potential therapeutic indications for 188/186 Re(V)DMSA. The study also demonstrates the valuable supporting role a (99)Tc(m)(V)DMSA scan can play in the confirmation as well as evaluation of the extent of malignant infiltration in a suspected superscan in routine skeletal scintigraphy. In addition, a (99)Tc(m)(V)DMSA scan detected a number of metastatic lesions in and around joints and regions with previous surgical intervention that were inconclusive in the bone scan. The results in a few patients who were available for repeat scintigraphy following treatment, support the convincing evidence that (99)Tc(m)(V)DMSA accumulation may be a sensitive indicator of patient response to therapy. This might have an important bearing in the context of increasing "cold" bisphosphonate usage in the treatment of skeletal metastases, where skeletal scintigraphy with a radiolabelled bisphosphonate derivative can often be fallacious because of competitive inhibition by the non-labelled form.

Adolescent↗
PubMed2000

The clinical and biologic significance of abnormal lipid profiles in patients with myelodysplastic syndromes.

Serum lipid profiles were obtained in 108 patients with myelodysplastic syndrome (MDS) and compared to 28 healthy volunteers. Serum cholesterol and low-density and high-density lipoproteins (LDL and HDL) were found to be significantly lower in MDS patients than in normals (p = 0.0001, 0.0038 and 0.037, respectively). This difference was significant for all MDS categories. Serum cholesterol and HDL were negatively related to biopsy cellularity (p = 0.001 and 0.0001, respectively), and serum triglycerides were negatively related to labeling index (p = 0.0003). No differences were noted in the lipid profiles of MDS patients with normal versus abnormal karyotypes. However, low-risk MDS patients with abnormal karyotypes had significantly lower triglyceride levels compared with the high-risk patients (p = 0.027), as did low-risk patients with normal cytogenetics (p = 0.015). Serum HDL levels were significantly higher for the low-risk group with normal cytogenetics as well (p = 0.003). We conclude that serum cholesterol, LDL, and HDL are significantly reduced in MDS patients, probably indicating excessive intracellular lipid biosynthesis in the expanding clone. These relatively simple measurements could serve as important prognostic markers and reliable indicators of disease activity in individual patients. Prospective studies to determine their utility as independent variables that guide the need for active therapeutic intervention are warranted.

Adult↗
PubMed1999

Cardiovascular and cancer mortality among Canadians of European, south Asian and Chinese origin from 1979 to 1993: an analysis of 1.2 million deaths.

BACKGROUND: Cardiovascular disease and cancer are important health problems worldwide, yet our knowledge of these conditions is derived principally from populations of European descent. To investigate ethnic variations in major causes of death in Canada, the authors examined total and cause-specific mortality among European, south Asian, and Chinese Canadians. METHODS: Canadians of European, south Asian and Chinese origin were identified in the Canadian Mortality Database by last name and country of birth and in the population census by self-reported ethnicity. Age-standardized death rates by cause, per 100,000 population, were calculated for ages 35 to 74 years from 1979 to 1993 and in 5-year intervals grouped around census years (1979/83, 1984/88 and 1989/93). RESULTS: Rates of death from ischemic heart disease were highest among Canadians of south Asian origin (men 320.2, women 144.5) and European origin (men 319.6, women 109.9) and were markedly lower among Canadians of Chinese origin (men 107.0, women 40.0); the rates declined significantly in all 3 groups over the study period. Rates of death from cerebrovascular disease were relatively low and showed less ethnic variation (Canadian men of European, south Asian and Chinese origin 49.5, 47.0 and 45.8 respectively; Canadian women of European, south Asian and Chinese origin 34.8, 39.0 and 42.2 respectively) and declined similarly in all groups over time. Rates of death from cancer were highest among Canadians of European origin (men 343.6, women 236.2), intermediate among those of Chinese origin (men 258.1, women 161.6) and lowest among those of south Asian origin (men 122.3, women 131.3). Over time, cancer mortality increased in Canadians of European origin but remained constant or declined in those of south Asian and Chinese origin. INTERPRETATION: Substantial differences exist in rates of death from ischemic heart disease and cancer among European, south Asian and Chinese Canadians.

Adult↗
PubMed1999

Trilateral retinoblastoma with an RB1 deletion inherited from a carrier mother: a case report.

A presentation of intracranial tumor in bilateral and unilateral retinoblastoma with or without family history is termed as trilateral retinoblastoma (TRB). It always occurs either as a pineal tumor or supra/parasellar tumor, which differ in presentation and prognosis. We report here the first case of TRB with transmission of retinoblastoma gene (RB1) deletion from an unaffected mother (a carrier), presenting as concurrent intracranial neoplasm with bilateral retinoblastoma. The presence of RB1 mutation in both child and mother could be responsible for development of intracranial neoplasm which occurred simultaneously with bilateral RB in our patient. Our patient, who had a suprasellar mass, received radiation and intrathecal chemotherapy, and died 6 months after diagnosis. The occurrence of intracranial tumor in an asymptomatic stage can be avoided by routine computed tomography (CT) and magnetic resonance imaging (MRI) scan, and improved survival can be achieved by aggressive multimodality therapy.

Adult↗
PubMed1999

Increased winter mortality from acute myocardial infarction and stroke: the effect of age.

OBJECTIVES: We examined seasonal variations in mortality from acute myocardial infarction (AMI) and stroke by age using 300,000 deaths in the Canadian Mortality Database for the years 1980 to 1982 and 1990 to 1992. BACKGROUND: The effect of age on environmental determinants of AMI and stroke is not well understood. METHODS: Seasonal variations were analyzed by month and for the four seasons (winter beginning in December). A chi-square test was used to test for homogeneity at p < 0.01, and relative risk ratios (RRs) for high and low periods were determined in relation to the overall mean. For each of four age subgroups, the magnitude of the seasonal variation was reported as the difference in mortality between the highest and lowest frequency seasons. RESULTS: By month, AMI deaths were highest in January (RR = 1.090) and lowest in September (RR = 0.904), a relative risk difference of 18.6%. The seasonal mortality variation in AMI deaths (winter vs. summer) increased with increasing age: 5.8% for <65, 8.3% for 65 to 74, 13.4% for 75 to 84 and 15.8% for >85 years (p < 0.005 for trend). Stroke mortality peaked in January (RR = 1.113) and had a trough in September (RR = 0.914), a relative risk difference of 19.9%. The seasonal variation in stroke mortality also increased with age. Seasonal variations were not seen in those aged <65 years, compared with 11.6% for 65 to 74, 15.2% for 75 to 84 and 19.3% for >85 years (p < 0.005 for trend). CONCLUSIONS: The elderly demonstrate a greater winter increase in AMI and stroke mortality than younger individuals. An understanding of these seasonal patterns may provide novel avenues for research in cardiovascular disease prevention.

Age Factors↗
PubMed1999

Double-blind study of clozapine dose response in chronic schizophrenia.

OBJECTIVE: This study explored the relative efficacy of three different doses of clozapine. METHOD: Fifty patients who met Kane et al.'s criteria for treatment-refractory schizophrenia or schizoaffective disorder were studied. All subjects were randomly assigned to 100, 300, or 600 mg/day of clozapine for 16 weeks of double-blind treatment. Forty-eight patients completed this first 16 weeks. Of the 50 patients, 36 went on to second and third 16-week trials of double-blind treatment at the remaining doses. RESULTS: Four subjects (8%) responded to the first 16-week condition, and one subject (2%) responded to the next 16-week crossover condition. A chi-square comparison of the response rates from the three dose groups failed to show a significant effect. An analysis of variance (ANOVA) comparison of Brief Psychiatric Rating Scale-Anchored (BPRS-A) total change scores from baseline to last observation carried forward showed a significant dose effect (600>300>100 mg/day) at 16 weeks of treatment. A crossover ANOVA of the BPRS-A total scores from the 48-week study also showed that the main effect for dose was highly significant; the 100-mg/day dose gave the higher (poorer) values, and the 300- and 600-mg/ day doses gave equal (better) values. Gender played a role in clinical response to treatment at 100 mg/day. CONCLUSIONS: Clozapine treatment at 100 mg/day was less effective than at 300 or 600 mg/day. At 100 mg/day, women responded better than did men. The 600 mg/day group had the best results, but an occasional patient required up to 900 mg/day. Overall response rates were lower than expected.

Antipsychotic Agents↗
PubMed1998

Absence of changes in antidiuretic hormone, angiotensin II, and atrial natriuretic peptide with clozapine treatment of polydipsia-hyponatremia: 2 case reports.

BACKGROUND: Polydipsia-hyponatremia is a poorly understood disorder that causes considerable mortality and morbidity. Hyponatremia in polydipsia-hyponatremia has been attributed to disturbances in antidiuretic hormone (ADH) function. Improvements in polydipsia-hyponatremia during clozapine treatment offered the chance to see if levels of ADH and other hormones associated with osmoregulation changed with improvement in biochemical and clinical measures of polydipsia-hyponatremia. METHOD: In this preliminary, longitudinal study, we studied 2 male schizophrenic patients (DSM-III-R) who had polydipsia-hyponatremia. Measures were (1) biochemical and clinical: serum sodium and osmolality, urine osmolality and specific gravity, normalized diurnal weight gain, and estimated urine volume and (2) endocrine: ADH, angiotensin II, atrial natriuretic peptide, and prolactin. Measures were collected during 2 months of baseline (typical neuroleptic) and 6 months of clozapine treatment. RESULTS: Single-case statistical procedures showed significant changes in sodium levels (a.m. and p.m.), estimated urine volume, and a.m. urine specific gravity in both patients and significantly decreased diurnal weight gain in 1 patient. Both serum and urine osmolality showed improvement, but values did not reach statistical significance. Low baseline ADH levels persisted through 6 months of clozapine treatment and showed no changes in the context of improvements in serum sodium and osmolality. No significant changes were seen in levels of angiotensin II and atrial natriuretic peptide. CONCLUSION: Given the limitations of this study, there is some evidence to suggest that the improvements in serum sodium and osmolality during clozapine treatment of polydipsia-hyponatremia may not be related to serum levels of ADH, although altered ADH receptor function cannot be ruled out. These data need to be extended in larger samples.

Adult↗
PubMed1998

At risk of first or recurring heart disease.

OBJECTIVES: The self-reported prevalence of risk factors for heart disease among Canadians with and without heart disease is estimated. The characteristics associated with these risk factors are examined in order to identify groups to be targeted for primary and secondary prevention. DATA SOURCE: The data are from the household component of the 1994/95 National Population Health Survey (NPHS). ANALYTICAL TECHNIQUES: For the population aged 20 and older with and without heart disease, bivariate and multiple regression analyses were used to determine associations between four risk factors (smoking, high blood pressure, diabetes, and inactivity) and demographic characteristics and socioeconomic status. MAIN RESULTS: According to the NPHS, 4.4% of people aged 20 and older reported that they heart disease. However, many more adults had risk factors for this disease. As well, about one-quarter of those without heart disease and half of those with heart disease had two or more risk factors. To some extent, many of these risks are modifiable. The groups particularly at risk were people older than 35, those with less than high school graduation, those in households with inadequate income, people who consumed three or more drinks a day, and residents of the Atlantic provinces, Quebec and Ontario.

Adult↗
PubMed1998

Current and future hospitalization after heart attack.

OBJECTIVES: This article provides an overview of patients who were hospitalized in 1993/94 because of acute myocardial infarction (AMI) and projects how many AMI patients there could be in the future. DATA SOURCE: The Person-Oriented Information Data Base was used for this analysis. ANALYTICAL TECHNIQUES: Hospital inpatients who had a primary diagnosis of AMI were analyzed, as well as their subsequent hospitalizations for coronary heart disease in the fiscal year. The age-sex specific hospitalization rates were used with population projections to estimate future hospital use. MAIN RESULTS: Of the nearly 45,000 Canadians who were discharged from hospital in 1993/94 with a primary diagnosis of AMI, most (72%) had only one hospital stay within the fiscal year, but 18% had two related stays, and 10% had three or more. AMI patients were hospitalized an average of 14.6 days. The projected number of AMI patients and the number of hospital days used will increase by approximately 36% each decade to the year 2026.

Adult↗
PubMed1998

Variations in angioplasty and bypass surgery.

OBJECTIVES: This article describes rates of and times to revascularization procedures for heart attack patients. DATA SOURCE: The data are from Statistics Canada's Person-Oriented Information Data Base. Hospital discharge records for heart attack patients were linked for fiscal years 1992/93 and 1993/94. ANALYTICAL TECHNIQUES: Hospital patients admitted between April 1 and September 30, 1993 with a primary diagnosis of acute myocardial infarction (AMI) were followed for six months to determine what percentage underwent percutaneous transluminal coronary angioplasty and/or coronary artery bypass graft surgery. Analyses of time-to-procedure were performed for those patients who had not been hospitalized for AMI in the previous 12 months. MAIN RESULTS: Approximately 24,000 Canadians were discharged from hospital during the first half of fiscal year 1993/94 with a diagnosis of AMI. Within six months, 8.7% had an angioplasty and 6.7% had a bypass; overall, 14.9% were revascularized. Women were less likely than men to have a bypass, but angioplasty rates did not differ significantly. The rate of revascularization declined with age. After adjusting for age and sex, rates were higher in the western provinces.

Adult↗
PubMed1997

Classifying ethnicity utilizing the Canadian Mortality Data Base.

UNLABELLED: The study of ethnic differences in disease is a methodological challenge as ethnicity is often not identified in existing datasets and surrogate measures need to be used. We have developed a novel methodology combining last name and country of birth to study mortality patterns of Canadians of South Asian (SA) and Chinese (CH) ethnic origin and have compared death rates among SA, CH, and White (WH) Canadians. METHODS: SA and CH were identified in the Canadian Mortality Data Base (CMDB) using the last name and country of birth of the deceased. Records of people who had been born in countries with large South Asian and Chinese populations (e.g. India, Pakistan, China, Hong Kong) were selected and manually screened by last name. A name directory was then created of distinct South Asian and Chinese names and this directory was used to search all other records in the CMDB for SA and CH deaths. Where necessary, other identifying characteristics such as first name and parents' last name were also used. Population counts were obtained from the Census self-reported question on ethnicity for SA and CH. WH were identified as non-immigrant Canadians who were neither SA nor CH. The method of assigning ethnicity in the CMDB and Census were assessed for comparability and issues of validity and reliability were addressed. RESULTS: Using this method, 10,989 SA and 21,548 CH deaths were identified. There was marked heterogeneity in birthplace, with only 56% of SA born in South Asia and only 74% of CH born in Greater China. Last names had high validity for self-reported ethnicity in a population sample of SA and were highly reproducible. Mortality rates varied dramatically between groups studied. SA and WH had high rates of ischemic heart disease while stroke mortality was similar among all three groups. Cancer death rates were high in CH and WH and much lower in SA. CONCLUSION: Last names and country of birth can be used to determined ethnicity of SA and CH with validity and reliability, and leads to a more accurate classification than country of birth alone. The contrasting patterns observed in mortality from major causes of death suggest many interesting hypotheses for further study.

Adult↗
PubMed1997

The effects of clozapine on symptom clusters in treatment-refractory patients.

Preliminary results of a double-blind clozapine study in a population of chronic psychotic patients at a state psychiatric facility are reported. Thirty "treatment-refractory" schizophrenic patients given a diagnosis according to DSM-III-R criteria (mean age of 44 +/- 9.1 years and a duration of illness of 24.9 +/- 8.8 years) who received 300 mg or 600 mg of clozapine and randomized in a double-blind fashion were analyzed. Subjects were evaluated using the Brief Psychiatric Rating Scale (BPRS) and the Clinical Global Impression (CGI) Scale on a weekly basis for 16 weeks. Based on the changes in their CGI scores at week 16 of clozapine treatment, subjects were retrospectively categorized as "improvers" (N = 12) and "nonimprovers" (N = 18). The two groups were compared for changes in total BPRS and BPRS factor scores. In terms of total BPRS scores, we expected a difference between the two groups because they were categorized based on changes in their CGI scores. However, the total BPRS scores in improvers showed a significant decrease by week 6 of clozapine treatment. On analyzing the four BPRS factors, the improvers showed improvement in the thinking disturbance factor by week 1 that remained steady from week 7. On the hostility-suspiciousness factor, the improvers showed an improvement across time when compared with nonimprovers. The withdrawal-retardation factor showed improvement in both groups across time, whereas the anxiety-depression factor was least influenced by clozapine. These observations suggested that all BPRS symptom factors did not uniformly contribute to improvement in overall psychopathology, which was observed as a decrease in total BPRS scores.

Adult↗
PubMed1996

Clozapine withdrawal effects and receptor profiles of typical and atypical neuroleptics.

Withdrawal effects of neuroleptics have not received much attention. Clozapine withdrawal phenomena have been attributed to psychosis arising from D2 supersensitivity, which is unlikely since it has minimal action on D2 receptors. The time course and clinical features of this phenomenon suggest that cholinergic overdrive and gamma-aminobutyric acid (GABA) supersensitivity occurs after withdrawal, since it is strongly anticholinergic and has a GABAergic action. Recently, a number of patients showed marked decompensation when they were switched from clozapine to risperidone, especially when they were rapidly tapered off clozapine. This was probably more due to withdrawal effects than the primary psychosis or a lack of efficacy of risperidone. A slow withdrawal schedule would facilitate homeostatic mechanisms; anticholinergics would be useful in clozapine withdrawal. This area has not received any attention from researchers, nor are there any guidelines for clinicians. This will be particularly important with the widespread use of atypical agents in the future.

Antipsychotic Agents↗
PubMed1996

Extracorporeal methods of vascular control for difficult IVC procedures.

Surgical procedures in the juxtaheptic and intrapericardial inferior vena cava (IVC) are difficult because of the complexity of achieving vascular control in the area. We describe 10 patients with a variety of pathologies in this region who underwent venovenous bypass (VVB) or cardiopulmonary bypass with hypothermic circulatory arrest (CBCA). Renal cell carcinoma with IVC extension was present in three patients (with tumor extension into the right atrium in two), adrenal adenocarcinoma in one, septic IVC thrombus in one, and blunt IVC/hepatic trauma in five. Those patients without atrial involvement underwent VVB with a mean bypass time of 40 minutes (range 12-144). Those patients with tumor extension into the right atrium underwent CBCA with systemic hypothermia to 18(0)C, total body exsanguination for a bloodless field, and removal of the tumor by cavotomy and right atriotomy. The mean bypass, aortic cross-clamp, and circulatory arrest times were 152, 92, and 36 minutes, respectively. Eight of the 10 patients did well and went home within 4 weeks of surgery. Two patients died, one from metabolic sequelae of exsanguinating IVC injury (VVB) and one from sepsis 2 weeks postoperatively (CBCA).

Adult↗
PubMed1996

Declining cesarean section rates: a continuing trend?

Since the mid-1980s, cesarean section rates in Canada have declined. By 1993, 18 of every 100 deliveries were by cesarean section, compared with close to 20 per 100 in 1987. As well, in 1993, 9 of every 100 deliveries were primary cesareans, down from a high of almost 11 per 100 in the mid-1980s. And the repeat cesarean section rate fell from 39 per 100 cesareans in the mid-1980s to 34 in 1993. A major factor in the downtum of cesarean section rates has been a steady increase in vaginal births after cesarean section (VBACs). From 1979 to 1993, the rate rose more than tenfold from 3 to 33 per 100 women who previously had a cesarean section. This trend toward VBAC deliveries was apparent among women in all age groups. Within Canada, there are large provincial differences in cesarean section and VBAC rates. In 1993, cesarean rates ranged from 15 per 100 deliveries in Manitoba to 22 in New Brunswick. VBAC rates ranged from 16 per 100 previous cesarean sections in New Brunswick and Newfoundland to 42 in Alberta. This article traces trends in cesarean section and VBAC rates in Canada and the provinces from 1979 to 1993. The data are based on individual patient admission/separation records of general and allied hospitals, that are submitted to Statistics Canada.

Adult↗