Prevalence of risk factors for cardiovascular disease in Canadians 55 to 74 years of age: results from the Canadian Heart Health Surveys, 1986-1992

BACKGROUND: By 2016, the proportion of Canadians older than 65 years of age will increase to 16%, and there will be an increase in the absolute number of cases of cardiovascular disease in older Canadians. The Canadian Heart Health Surveys database provides information about this population upon which health policy related to cardiovascular disease can be based. This paper presents for the first time population-based data on the risk factors for cardiovascular disease in older Canadians. METHODS: Canadians from all 10 provinces participated in surveys of cardiovascular risk factors; health insurance registries were used as sampling frames. In each province, probability samples of 2200 adults 18 to 74 years old not living in institutions, on reserves or in military camps were asked to participate in interviews and to undergo testing at clinics for major risk factors for cardiovascular disease. RESULTS: A total of 2739 men (response rate 70%) and 2617 women (response rate 66%) aged 55 to 74 years participated in the survey and also provided follow-up clinical measurements at the clinic. Overall, 52% of participants were hypertensive, 26% had isolated systolic hypertension, and 30% had a total blood cholesterol level of 6.2 mmol/L or greater. Rates of current smoking were lower in women than men (17% v. 22%). Overall, 87% of men and 78% of women who were current smokers smoked at least 10 cigarettes per day. Only slightly more than half of participants exercised at least once a week for at least 15 minutes, and almost half had a body mass index of 27 or greater. In only 4% was no major risk factor for cardiovascular disease detected. INTERPRETATION: Significant numbers of older Canadians have one or more major risk factors for cardiovascular disease. Many of these risk factors are amenable to modification.     

Relationship between surface H-2 concentration, size of different target cells, and lysis by cytotoxic T cells

We have examined the parameters of target cell cross-sectional area and surface H-2 concentration in relation to their susceptibility to cytotoxic T-cell-mediated lysis, using a series of commonly used murine target cells of the H-2k haplotype. We used a sensitive immunoferritin labeling technique and electron microscopy to estimate relative cell diameter and H-2 concentration combined with standard 51Cr-release assays for cytotoxicity. We found that susceptibility to cytotoxic T-cell lysis was not related consistently to either factor alone, but was related to a combination of the two, such that above a certain value for the product of the two factors, no further increase in cytotoxic T-cell efficiency was seen. The information presented here should be of value to workers seeking to select a target cell type that will maximize the sensitivity of 51Cr-release-based assays for the detection of cytotoxic T cells.     

Coevolution of the glucose dehydrogenase gene and the ejaculatory duct in the genus Drosophila

The glucose dehydrogenase gene (Gld) in Drosophila melanogaster exhibits a unique spatial and temporal pattern of expression. GLD expression switches from a non-sex-limited state at the pupal stage to a male-limited state at the adult stage. At the adult stage, the enzyme is restricted to the ejaculatory duct. Within the genus Drosophila, the ejaculatory duct has undergone a simple morphological divergence. In order to determine whether correlated changes in GLD expression had occurred, GLD activity during the pupal and adult stages was determined for several Drosophila species. It was found that virtually all of the species exhibit pupal GLD activity, whereas only those species with an expanded ejaculatory duct express male-limited GLD. The results of interspecific genital imaginal disc transplantation experiments indicate that the expanded morphology and GLD expression do not require any species- or sex-specific diffusible factors. An apparent regulatory polymorphism exists within the D. takahashii species with respect to male-limited GLD expression.      

The cell-mediated immune response to ectromelia virus infection. I. Kinetics and characteristics of the primary effector T cell response in vivo.

The cell-mediated immune (CMI) response to ectromelia virus infection in mice was studied. Virus doses from 4 × 10² up to 5 × 10⁴ PFU of an attenuated strain inoculated intravenously (iv) all induced cytotoxic T cell responses in the spleen as measured in a ⁵¹Cr release assay using virus-infected target cells. Higher virus doses gave larger responses. There was little variation between individual animals, and mice ranging in age from 4–22 weeks gave similar responses. Following iv infection, virus grew logarithmically in spleen for 2 days, then titers declined to undetectable levels by day 5. The peak of the virus-specific cytotoxic T cell response occurred at 5–6 days post-infection, as determined by calculation of effector units based on a linear log-log relationship between killer cells added and targets lysed. T cells responsible for virus clearance in vivo gave similar kinetics, suggesting the possibility that both functions are mediated by the same T cell subset. Two other categories of cytotoxic activity were also generated at low levels in the spleen during ectromelia infection or during infection with a bacterium, Listeria monocytogenes. These activities were significantly sensitive to anti-δ and complement treatment, suggesting T cell dependence, but participation of other mechanisms has not been rigorously excluded. One category lysed allogenic target cells and reached a peak at 4 days post-infection. The other lysed H-2-compatible cells, syngeneic embryo cells, and some syngeneic tumor cells but not syngeneic macrophages, and was present at similar low levels through days 1–4. These different kinetics and evidence from “cold” target competition experiments suggested that the total cytotoxic activity of immune spleen cell populations was a composite of the activities of separate cellular subsets (probably mainly T cells), killing of any one target cell type being the responsibility of a subset with receptors at least partly specific for antigens on that target cell.     

A report on methods to reduce,refine and replace animal testing in industrial toxicology laboratories

The Committee to Promote Principles of Reduction, Refinement and Replacement of Animal Testing in Industrial Toxicology Laboratories was established in 1987 to work toward industrywide improvements in laboratory animal testing methods. The committee's goals are to gather information about effective nonanimal testing techniques and other methods of conserving and improving the care of laboratory animals, to work toward the systematic validation of nonanimal alternatives, and to disseminate useful information about progressive programs and policies throughout the industrial toxicology community. This is the first in a continuing series of reports the committee plans to produce as part of an ongoing program to promote communication among industrial toxicologists about successful methods of reducing, refining and replacing animal testing. Here are some of the report's major findings: (1) Animal care and use committees charged with the oversight of laboratory animal use are a universal practice at the companies surveyed. (2) Significant reductions in the number of animals used for acute toxicity testing have taken place at all the companies during the last 5- to 10-year period. (3) Structure-activity relationships (predicting a test compound's properties based on the known properties of familiar chemicals with similar structures) are widely used to minimize, but not replace, the use of animals. (4) Tissue and organ culture systems are being used with increasing frequency for screening and mechanistic studies, but are not completely replacing animal evaluations as a final step. (5) There is a pressing need for the systematic and scientifically sound validation of nonanimal alternative techniques to reduce the use of animals in toxicology testing while satisfying requirements for the protection of public safety.     

Total antioxidant capacity – a novel early bio-chemical marker of oxidative stress in HIV infected individuals

Background  

Oxidative stress induced by the production of reactive oxygen species may play a critical role in the stimulation of HIV replication and the development of immunodeficiency. This study was conducted as there are limited and inconclusive studies on the significance of a novel early marker of oxidative stress which can reflect the total antioxidant capacity in HIV patients,     

Exhaustion of type I interferon response following an acute viral infection

Viral infections often cause a period of heightened susceptibility to a secondary infection but the cause of this phenomenon is unknown. We found that a primary viral infection in mice rapidly triggers an IFN-I-dependent partial activation state in the majority of B and T lymphocytes, which reverts to a resting phenotype within 5 days. When a secondary infection with an unrelated virus occurred 5 to 9 days after the primary infection, no recurrence of marked activation of lymphocytes was observed. This was not due to an inherent inability of the previously activated cells to undergo renewed partial activation, because they responded when challenged with virus after transfer into "naive" recipients. Instead, the failure to respond optimally resided in the original host's incapacity to mount an IFN-I response to the secondary infection during this time period. Thus, transient immunosuppression through exhaustion of IFN-I production during an acute viral infection creates a time period of enhanced susceptibility to secondary infection.