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Biomedical subjects

J Lindsay

Publications and source records attributed to J Lindsay.

At least 37 records · Page 2Linked to original sources
PubMed2001

Data collected in the Canadian Study of Health and Aging.

The Canadian Study of Health and Aging collected data focusing on the epidemiology of dementia, using interviews and questionnaires, clinical and neuropsychological examinations, physical measurements and blood collection, and access to public records such as death certificates, from people 65 and over in community (N = 9,008) institutional settings (N = 1,255). The study produced 12 data sets, including community health interviews, clinical and neuropsychological assessments, risk factor questionnaires, and caregiver interviews. This report describes the data collection and processing procedures, summarizes the content of each data set, and outlines the information collected in sufficient detail to permit its suitability for secondary analyses to be scrutinized.

Aged↗
PubMed2001

Study organization in the Canadian Study of Health and Aging.

The Canadian Study of Health and Aging was a complex undertaking that faced management challenges not encountered by smaller-scale projects. The study followed 10,263 elderly people in 18 study centers spanning six time zones; it was administered in two languages, and over 70 investigators were involved. The data collected from each participant were not fixed, but varied according to the results of earlier testing. The data could include a screening interview, a self-completed risk factor questionnaire, an interview with a relative, a clinical examination, neuropsychological testing, blood samples, and neuroimaging. This report describes the approach taken to organize the study, to track participants, and to monitor adherence to the study protocol. It also describes the human organizational aspects, including systems for staff training, for communicating among study centers, and for coordinating the publication of results. The discussion proposes some guiding principles for administering multicenter studies.

Aged↗
PubMed2001

Molecular genetics of SaPI1--a mobile pathogenicity island in Staphylococcus aureus.

The Staphylococcus aureus gene for toxic shock toxin (tst) is carried by a 15 kb mobile pathogenicity island, SaPI1, that has an intimate relationship with temperate staphylococcal phage 80alpha. During phage growth, SaPI1 is excised from its unique chromosomal site, attC, replicates autonomously, interferes with phage growth, and is efficiently encapsidated into special small phage heads commensurate with its size. Upon transfer to a recipient organism, SaPI1 integrates at attC by means of a self-coded integrase. One or more phage functions are required for excision, autonomous replication and encapsidation of the element and, thus, the overall relationship between SaPI1 and 80alpha is similar to that between coliphages P4 and P2. Among other staphylococcal phages tested, only phi13 interacts with SaPI1, inducing excision but not replication or transfer of the element.

Attachment Sites, Microbiological↗
PubMed2000

Incidence, management, and outcome of coronary artery perforation during percutaneous coronary intervention.

We have analyzed the incidence, management, and outcome of 84 cases of coronary artery perforation in patients who underwent percutaneous coronary intervention at our institution. This complication was more frequent in female patients and in patients who underwent lesion modification with atheroablative devices. A total of 8 patients (9.5%) died after the procedure. They were usually older and had a higher incidence of cardiac tamponade; a larger percentage of these patients underwent emergency surgery than those who survived.

Adult↗
PubMed2000

Ethnicity does not affect outcomes of coronary angioplasty.

BACKGROUND: Access to high quality medical care and especially to complex procedures may be adversely affected in members of a minority ethnic group or a lower socioeconomic class. For example, Caucasians undergo coronary artery bypass grafting (CABG) or percutaneous transluminal coronary interventions (PTCI) twice as frequently as African-Americans. Data exist to suggest that African-Americans derive less benefit than Caucasians from CABG. HYPOTHESIS: We investigated the possibility that outcomes of catheter-based coronary angioplasty might also be less favorable in minority populations. METHODS: We analyzed in-hospital outcomes in 6,559 consecutive patients who underwent PTCI in our laboratory. In 37 ethnicity was classified as "other," 5,203 (79.8%) were identified as Caucasians, 863 (13.2%), as African-Americans, and 456 (7.0%), as Hispanics. Twelve baseline clinical, angiographic, and procedural characteristics were entered into a computerized data base. Hospital complications were identified by trained quality assurance nurses. RESULTS: Substantial differences in baseline characteristics existed between the populations. Despite these differences, on univariate comparison of ethnicity and outcome, no differences between ethnic groups were found with a single exception. Mortality in Hispanics was higher than in the other two populations. (2.0 vs. 0.7 and 0.8%, respectively, p = 0.008). However, when this was adjusted for baseline characteristics, the difference was not significant. CONCLUSIONS: In contrast to previous studies suggesting less favorable outcomes of CABG in African-American patients, this analysis demonstrates an equal frequency of procedural success and rate of hospital complications for PTCI in that population, in Hispanics, and in Caucasians.

Aged↗
PubMed2000

Hyperthyroid heart disease.

The heart is an organ sensitive to the action of thyroid hormone, and measurable changes in cardiac performance are detected with small variations in thyroid hormone serum concentrations. Most patients with hyperthyroidism experience cardiovascular manifestations, and the most serious complications of hyperthyroidism occur as a result of cardiac involvement. Recent studies provide important insights into the molecular pathways that mediate the action of thyroid hormone on the heart and allow a better understanding of the mechanisms that underlie the hemodynamic and clinical manifestations of hyperthyroidism. Several cardiovascular conditions and drugs can interfere with thyroid hormone levels and may pose a difficulty in interpretation of laboratory data in patients with suspected thyroid heart disease. The focus of this report is a review of the current knowledge of thyroid hormone action on the heart and the clinical and hemodynamic laboratory findings as well as therapeutic management of patients with hyperthyroid heart disease.

Atrial Fibrillation↗
PubMed2000

Factors affecting the severity of motor vehicle traffic crashes involving elderly drivers in Ontario.

A population-based cross-sectional study was conducted to examine factors affecting the severity of motor vehicle traffic crashes (MVTCs) involving elderly drivers in Ontario. The study population included drivers aged 65 and over involved in injury-producing MVTCs between 1988 and 1993 on Ontario public roads. Information was obtained from the Canadian Traffic Accident Information Databank (TRAID) compiled from police reports. The severity of MVTC was classified as fatal, major, minor or minimal. Comparisons between fatal-, major-, minor- and minimal-injury crashes were conducted. Percentage distributions of crashes at each level of severity involving elderly drivers were examined according to specific factors and tested using the X2 test. Multivariate unconditional logistic regression was used to calculate the estimated relative risk as odds ratios (ORs) while controlling for confounding factors. A number of factors were significantly related to the increased risk of fatal-injury in crashes compared with a reference category for each variable. These included age (OR = 1.4 for 70-79 and OR = 2.3 for 80 + ), sex (OR = 1.4 for males), failing to yield right-of-way/disobeying traffic signs (OR = 1.7), non-use of seat belts (OR = 4.0), ejection from vehicle (OR = 11.3), intersection without traffic controls (OR = 1.7), roads with higher speed limits (OR = 7.9 for 70-90 km/h; OR= 5.8 for 100 km/h), snowy weather (OR= 1.6), head-on collisions (OR=55.1), two-vehicle turning collisions (OR = 3.1 for left-turn, OR = 8.7 for right-turn), overtaking (OR = 5.6), and changing lanes (OR = 2.1). Adverse medical/physical conditions increased the risk of fatality by a factor of 5 for drivers 75-79 years of age and a factor of 3.5 for those 80 years and over. However, in the age group 65-74, medical/physical condition did not appear to be related to risk of fatality. Similar but weaker associations between these factors and risk of major- and minor-injury in crashes were also observed. To reduce the severity of crashes involving elderly drivers, strategies could target specific factors such as head-on collisions, single-vehicle collisions, and traffic controls at intersections. Driver conditions such as medical/physical conditions and driver actions such as failing to yield right-of-way/disobeying traffic signs should be examined further.

Accidents, Traffic↗
PubMed2000

Vascular dementia : incidence and risk factors in the Canadian study of health and aging.

BACKGROUND AND PURPOSE: Very few population-based studies have systematically examined incident vascular dementia (VaD). From the Canadian Study of Health and Aging cohort, incidence rates of VaD were determined and risk factors analyzed. METHODS: This was a cohort incidence study that followed 8623 subjects presumed to be free of dementia over a 5-year period. The risk factors were examined with a nested prospective case-control study. Exposure was determined by means of a risk factor questionnaire administered to the subject or a proxy at the beginning of the study. RESULTS: On the basis of 38 476 person-years at risk, the annual incidence rate was estimated to be 2.52 per thousand undemented Canadians (95% CI 2. 02 to 3.02). Including an estimation of the probability of VaD among the decedents, this figure rose to 3.79. For the risk factors study, 105 incident cases of VaD according to the NINCDS-AIREN criteria were compared with 802 control subjects. Significant risk factors were: age (OR=1.05), residing in a rural area (2.03), living in an institution (2.33), diabetes (2.15), depression (2.41), apolipoprotein E epsilon4 (2.34), hypertension for women (2.05), heart problems for men (2.52), taking aspirin (2.33), and occupational exposure to pesticides or fertilizers (2.05). Protective factors were eating shellfish (0.46) and regular exercise for women (0.46). There was no relation with sex, education, or alcohol. CONCLUSIONS: The study confirmed some previously reported risk factors but also suggested new ones. It raised concerns about the prescription of aspirin and perhaps other factors related to rural life.

Age Distribution↗
PubMed1999

Procedural results of coronary angioplasty but not late mortality have improved in patients with depressed left ventricular function.

BACKGROUND: Published experience with coronary angioplasty in patients with severely depressed left ventricular (LV) ejection fraction indicates that procedural complications are more frequent in such patients than in those with normal or near normal LV function. Although the immediate outcomes of transcatheter revascularization in unselected populations have improved substantially since the procedures upon which these reports were based were performed, outcomes with this subset of patients has not been recently reviewed. HYPOTHESIS: This study was undertaken to document the results of the application of current transcatheter technology to this patient subset. METHODS: We analyzed data from 194 consecutive patients with a visually estimated LV ejection fraction < 30%, who underwent coronary angioplasty in this institution between January 1, 1995, and April 30, 1996, and compared their outcomes with those of 1,390 patients with normal LV function treated concurrently. RESULTS: Angiographic success in the two groups was similar. The hospital mortality of the patients with low ejection fraction was higher (2.6 vs. 0.6%, p = 0.02) than in concurrently treated patients with normal LV function. Other procedural complications were no more frequent than in such patients. Late mortality in patients with low ejection fraction was 16%, a similar value to that in older reports. CONCLUSION: Compared with older reports, current hospital outcomes of coronary angioplasty are improved in patients with severely depressed LV function. Unfortunately, late outcomes are not demonstrably better.

Aged↗
PubMed1999

Pathology of bailout coronary stenting in human beings.

OBJECTIVES: The aim of this study was to perform detailed postmortem analysis of bailout coronary stenting to gain insights into the mechanism of success or failure of the procedure. Bailout stenting is increasingly used for acute or threatened arterial closure after angioplasty. Few pathologic data from bailout stenting have been reported. METHODS AND RESULTS: The coronary arteries from 6 cases of bailout stenting were analyzed at autopsy. All stents were placed for extensive coronary dissection or abrupt vessel closure after balloon angioplasty. Twenty stents (11 Palmaz-Schatz and 9 Gianturco-Roubin stents) were placed in 8 coronary arteries, ranging from 1 to 5 stents per artery. After stenting, angiography showed good coronary flow in 3 of 6 cases. All patients died secondary to acute myocardial infarction. Histologically, in all cases, the stents were well opposed to the coronary artery wall, with a focally widely patent lumen by compression of the dissection plane. However, in 4 of 6 cases, there was residual dissection present in the nonstented portion of the arteries proximal, proximal to, and between stents or distal to the stented segment, resulting in focal luminal compression or obstruction. In 2 cases, bailout stenting effectively covered the dissection and prevented luminal compression. CONCLUSIONS: Bailout stenting for dissection after balloon angioplasty restores lumen patency in the stented segment. Residual dissection in nonstented segments adversely affects outcome and supports the need for continued development of new stents with increased trackability and tapering designs to more effectively treat major coronary dissections.

Adult↗
PubMed1999

Frequency of major adverse cardiac events within one month of coronary angioplasty: a useful measure of operator performance.

OBJECTIVES: To test one-month outcomes in a single center for their statistical power to corroborate conclusions derived from large multicenter databases. BACKGROUND: Only with large, multicenter databases has it been possible to demonstrate more frequent occurrences of complications in patients treated by "low-volume operators." Critics feel that such analyses mask excellent performance by many "low-volume operators." METHODS: In a high-volume cardiac catheterization laboratory in a large, nonuniversity teaching hospital, baseline clinical and angiographic characteristics were collected for a consecutive series of 1,029 patients treated by 37 percutaneous transluminal coronary intervention (PTCI) operators over a four-month period. One-month follow-up was obtained in 967 (94%) patients who form the basis for this analysis. RESULTS: Only the group of operators performing <50 cases annually had a major adverse cardiac event (MACE) (death, myocardial infarction or symptom-driven revascularization) rate at one month significantly greater than predicted from baseline characteristics. (Observed rate: 15.1%, expected: 9.7%, 95% confidence interval [CI]: 4.7%, 14.6%.) The difference was driven by the significantly more frequent rate at which repeat revascularization was performed in patients treated by that group of operators (observed: 13.8%, expected: 7.1%, 95% CI: 2.8%, 11.4%). CONCLUSIONS: As is true of analyses of large multicenter databases, lower volume operators as a group have less good outcomes than those performing more. The greater statistical power provided by one-month MACE rate offers advantages over the use of in-hospital complications for the analysis of operator performance.

Aged↗
PubMed1999

Patterns of self-reported health care use in injured and uninjured older adults.

METHOD: Using cross-sectional data obtained from the 1994 National Population Health Survey, we have compared self-reported health-care use between injured and non-injured older adults. RESULTS: Over 12 months, 9% of non-institutionalized people over 65 reported an injury. The commonest injuries were sprains or strains and fractures and half of these were caused by a fall. Older people sustaining injuries are more likely to spend a night in hospital and receive physiotherapy.

Accidental Falls↗
PubMed1999

Uncertain knowledge: a national survey of high school students' knowledge and beliefs about hepatitis C.

OBJECTIVE: Hepatitis C (HCV) has recently emerged as an important public health issue. This study documents young people's hepatitis C (HCV) knowledge, risk perceptions and sources of information. METHOD: Australia, 1997; nationally representative survey; sample of students in Years 10 and 12 in government secondary schools (n = 3,550). RESULTS: Students' knowledge about HCV was found to be extremely poor. Of the seven questions on hepatitis, only one was answered correctly by more than half the students. Few could differentiate between hepatitis A, hepatitis B and hepatitis C. Only a small number (12%) perceived themselves to be at risk of hepatitis and fewer than half (41%) had sought advice about hepatitis. CONCLUSION: There is a need for more HCV education and health promotion for secondary school students. IMPLICATIONS: Some lessons from HIV education can be readily transferred to this new epidemic but others cannot. There is a danger that HIV and HCV will be conflated in education programs.

Adolescent↗
PubMed1999

Same-sex attraction, drug injection and binge drinking among Australian adolescents.

OBJECTIVE: To document the prevalence of same-sex attraction among students in years 10 and 12 in Australian Government high schools and to assess the association between same-sex attraction, binge drinking and drug injection. METHOD: Cross-section survey by anonymous, self-administered questionnaire of 3,387 students in Years 10 and 12 of the Government school system in Australia. RESULTS: Approximately 6% of respondents reported being currently attracted to members of their own sex. Being attracted to members of the same-sex was associated with more frequent binge drinking among boys and girls, and a three- to four-fold increase in the likelihood of reporting injecting drug use both over the lifetime and within the previous 12 months. CONCLUSIONS: Adolescents attracted to members of the same-sex report engaging in elevated levels of health-limiting behaviours. There is an urgent need for further research to document the reasons for this. It is recommended that health promotion activities directed at moderating young people's drug and alcohol practices explicitly acknowledge the over-representation of same-sex attracted young people in their target audience.

Adolescent↗
PubMed1998

Prescription drug use and self-prescription among resident physicians.

CONTEXT: Self-prescription is common among practicing physicians, but little is known about the practice among resident physicians. OBJECTIVE: To determine prescription drug use and self-prescription among US resident physicians. DESIGN AND SETTING: Anonymous mail survey of all resident physicians in 4 US categorical internal medicine training programs in February 1997. MAIN OUTCOME MEASURES: Self-reported use of health care services and prescription medications and how they were obtained. RESULTS: A total of 316 (83%) of 381 residents responded; 244 residents (78%) reported using at least 1 prescription medicine and 162 residents (52%) reported self-prescribing medications. Twenty-five percent of all medications and 42% of self-prescribed medications were obtained from a sample cabinet; 7% of all medications and 11% of self-prescribed medications were obtained directly from a pharmaceutical company representative. CONCLUSIONS: Self-prescription is common among resident physicians. Although self-prescription is difficult to evaluate, the source of these medications and the lack of oversight of medication use raise questions about the practice.

Drug Prescriptions↗
PubMed1998

Determination of pretest probability for detection of a cardiovascular source of emboli by transesophageal echocardiography using clinical and transthoracic echocardiographic data.

Transesophageal echocardiographic findings and their effect on disease management were evaluated in 216 patients with suspected cardiovascular source of emboli. Clinical and transesophageal echocardiographic findings were useful in defining pretest probability for finding a probable cardiovascular source of emboli on transesophageal echocardiography.

Adult↗