A possible role for vitamins C and E in cataract prevention.

Biochemical evidence suggests that oxidative stress caused by accumulation of free radicals is involved in the pathogenesis of senile cataracts. If so, appropriate amounts of the antioxidant vitamins C and E might be expected to prevent or retard the process. Such activity has been observed in several in vitro and in vivo studies of experimentally-induced cataracts. A recent epidemiologic study found that cataract patients tended to have lower serum levels of vitamins C, E, or carotenoids than did control subjects. The present investigation, which compared the self-reported consumption of supplementary vitamins by 175 cataract patients with that of 175 individually matched, cataract-free subjects, revealed that the latter group used significantly more supplementary vitamins C and E (P = 0.01 and 0.004, respectively). Because the results suggested a reduction in the risk of cataracts of at least 50%, a randomized, controlled trial of vitamin supplementation in cataract prevention may be warranted.

Vitamin E intake and risk of cataracts in humans.

Experimental evidence suggests that oxidative stress due to the accumulation of free radicals plays a role in the pathogenesis of cataracts and that the process can be prevented or ameliorated by antioxidants. In addition, a recent study found that cataract patients tended to have lower serum levels of vitamins C, E, or carotenoids than did control subjects. This investigation, which compared the self-reported consumption of supplementary vitamins by 175 cataract patients with that of 175 individually matched, cataract-free subjects, revealed that the latter group used significantly more supplementary vitamins C and E (p = 0.01 and 0.004, respectively). Inasmuch as the observed reduction in risk of cataracts was at least 50%, a randomized, controlled trial of vitamin supplementation in cataract prevention seems justified.

A comparison of three methods to evaluate change in the spontaneous language of aphasic individuals.

Three methods for evaluating change in the spontaneous language of aphasic subjects were compared. Clinical judgments (CJ) of experienced speech-language pathologists showed excellent agreement and served as a comparison with the Shewan Spontaneous Language Analysis (SSLA) and the WAB Spontaneous Speech subtest. Although reliable and easy to use, however, the CJ method does not provide comprehensive information needed for treatment planning. The SSLA, although more time-consuming, provided comprehensive information and agreed highly with CJ for detecting change. The WAB method, although almost as economical timewise as the CJ method, did not agree as highly with CJ and did not provide adequate information for treatment planning.

The effect of psychosocial factors on lung cancer mortality at one year.

In this study newly diagnosed male and female lung cancer patients admitted to two Ontario Cancer Foundation treatment clinics were interviewed. Information was obtained on demographic variables, presence of other chronic illness and the following psychosocial attributes: locus of control, social support and personality traits. From the clinic charts, information on stage of disease and pathological diagnosis was obtained. After controlling for the effects of stage and pathological diagnosis, the following psychological variables were found to increase the odds of death from lung cancer among males and females combined at one year after diagnosis: a high need for one aspect of social support, a reserved personality and the extremes of the personality trait soberness vs enthusiasm.

Assessing hypertension control in the community: the need for follow-up measurements to ensure clinical relevance.

In community surveys of hypertension control the diagnosis is often based on blood pressure measurements taken on only one visit. The clinical diagnosis of hypertension requires demonstration of sustained blood pressure elevation. We conducted a survey that contrasted the results of these two approaches to determining the prevalence of hypertension and the extent to which hypertension is detected and treated. A multistage random sample of 2737 people was selected, examined and interviewed on up to three occasions. Rates of hypertension prevalence and control were computed from data from one, two and three visits. The prevalence of hypertension was overestimated by 30% when the diagnosis was based on data from one rather than three visits, the rates being 149 and 115/1000. The prevalence of undetected hypertension was overestimated by 350%, the rates being 27 and 6/1000. The proportion of subjects with controlled hypertension was underestimated by 23%, at 56%, compared with 73%. These results confirm the need for follow-up measurements to provide a valid assessment of hypertension control in the community.

Factors affecting the incidence of hypertension.

The incidence of hypertension was determined among 10,173 patients of general practices in southwestern Ontario studied from 1978 to 1982. For both sexes the incidence of hypertension rose with increasing age. The incidence was higher among men than among women until age 50, after which it was similar for the two sexes. Obesity was positively associated with incidence for both sexes. In men this association diminished significantly with increasing age. The similar trend in women fell just short of statistical significance. In men but not women heavy alcohol consumption was positively related to the incidence of hypertension. However, the broad definition of this variable may have obscured a relation in women. Among men the effect of obesity on the incidence of hypertension was less for heavy drinkers than for light drinkers. Smoking was not related to the incidence of hypertension in either sex.

Exercise training of men at retirement: a clinical trial.

The effects of one year of exercise training on cardiorespiratory fitness, levels of daily leisure activity, and blood lipids (cholesterol and high density lipoproteins) were studied in a prospective, randomized clinical trial. Two hundred and twenty-four men aged 55 to 65 years volunteered for the study and were randomly allocated to a control (n = 111) or an activity (n = 113) group with stratification on blue or white collar job classification. After the attrition due to loss to follow-up, 100 men remained in each of the control and activity groups. The exercising men met an average of 2.5 times per week over the year and their VO2 max or peak VO2 (ml X kg-1 X min-1) increased significantly (p = .001, 11%) compared with controls. There were no significant changes in maximal heart rate (155 bpm) and respiratory exchange ratio (1.1), although ventilation (80 to 90 l X min-1) increased significantly in the trained group. In addition, the VO2 at a heart rate of 125 bpm increased significantly (p less than .001) in the trained group (14.7%) over that observed in the control (1.9%). There were no significant differences between the groups with respect to the remaining end-points.

The effect of socioeconomic factors on the early prognosis of cancer.

Previous studies have suggested that cancer patients of low socioeconomic status (SES) have poorer short and long-term survival than cancer patients of higher SES. In this study male and female patients between the ages of 25 and 70, admitted to two Ontario Cancer Treatment and Research Foundation Clinics with newly diagnosed cancers of a number of common sites, were interviewed to obtain information on education and occupation, and chronic illnesses other than cancer. Information on stage of disease at diagnosis, exact pathologic diagnosis, date of diagnosis, and treatment before and after admission to the clinic was obtained from clinic charts. Using multiple logistic regression analysis to control for the effect of stage and other variables, there was no convincing evidence that cancer patients of low SES measured by either education or occupation had a less favourable outcome at one year after diagnosis from cancers of all sites combined or lung cancer specifically. The data suggested that any single measure of SES affects males and females differently.

Determinants of the training response in elderly men.

As part of a prospective randomized trial of the effect of regular exercise in older men, factors determining the magnitude of VO2max increase observed with endurance training were examined in 88 elderly [age 62.9 +/- 3.0 (SD) yr] males. VO2max before and after training was recorded as the highest VO2 observed during two incremental treadmill tests. One year of thrice weekly training sessions increased VO2max (12%, P less than 0.05) in the training group relative to baseline and to a control group (n = 100). The association between the post-training VO2max (VO2max, T2) and the following explanatory variables was assessed using multiple regression analysis: the initial VO2max (VO2max, T1); the reason for stopping the initial treadmill test: leisure time activity during the year previous to the study: the training intensity (speed of walking or running, pulse rate during training, and percentage of heart rate reserve); pulmonary function (forced expiratory volume in 1 s); adiposity (skinfold thickness at 8 sites) and frequency of training. VO2max T1, speed of walking or running during training, reason for stopping the treadmill test, and skinfold thickness were significantly related to post-training VO2max. The intensity and frequency of the training stimulus explained over 10% of the variance in the training effect. Subjects whose test was halted because of fatigue increased VO2max more than those whose test was discontinued for medical or other reasons, even when speed of running was held constant. Previous activity had only a weak effect on training response. The total variance explained by these independent variables was 62%.

Ventilation threshold and aging.

The ventilation threshold (VeT) in 60 healthy men ages 22 to 65 years was determined on a maximal treadmill test. The VeT was identified as the highest VO2 before the ventilatory equivalent for oxygen began to increase without a corresponding increase in the ventilatory equivalent for carbon dioxide. The VO2 max was significantly lower in the 60 compared with the 20-year-old group (with age, r = -.81). The VeT was significantly lower in the oldest compared with the youngest group (with age, r = -.69); however, the VeT as a percentage of VO2 max was significantly greater in the oldest group, (with age, r = .37). The reserve capacity (VO2 max minus VeT) was significantly lower in the older men (with age, r = -.75) and was due to a greater reduction in VO2 max than in VeT. With multiple regression analysis, the variability in VeT was determined primarily by VO2 max (65.8%) and not age. Decrease in strenuous activity with age may account for the large reduction in VO2 max, whereas maintained submaximal activity may attenuate the reduction in VO2 at the ventilation threshold, thus resulting in a large loss in functional reserve above the level of the VeT.

Isometric occupational exercise and the incidence of hypertension.

The effect on blood pressure of regular exposure to isometric exercise was studied by measuring the incidence of hypertension among 4,273 men classified according to occupational isometric activity. Incidence of hypertension was lower among men in jobs with moderate or heavy isometric activity. This difference persisted after statistical adjustment for age, social class, obesity, and use of alcohol.

Prevalence and control of hypertension in an Ontario county.

A survey of a representative population sample was carried out to evaluate the prevalence and control of hypertension in Middlesex County, Ontario. Of the 3067 subjects selected 2735 completed the initial interview. If the diastolic blood pressure was greater than 89 mm Hg in three readings, up to two further visits were made. The prevalence rate of hypertension in the sample was estimated to be 115/1000. Only 5.1% of the hypertensive subjects were unaware of their condition, and 5.4% were aware but not receiving treatment. In 16.9% the hypertension was treated but uncontrolled, while in 72.6% it was treated and controlled. The prevalence rate was significantly higher in the older subjects (p less than 0.0001). Control was better in the women and the older subjects. The results indicate that physicians in Middlesex County are detecting and treating most patients with hypertension; screening programs are thus not needed. Control of hypertension could be further improved by determining why the condition in those receiving treatment is not being controlled.

Verapamil in chronic atrial fibrillation: variable patterns of response in ventricular rate.

We determined the effects of single intravenous (10 mg) and oral (80, 160 mg) doses of verapamil in 8 digitalized patients with chronic atrial fibrillation. The time course of drug effect was analyzed with computer assistance by considering several measures in atrial fibrillation, including average R-R interval (ARR), shortest R-R interval (SRR), longest R-R interval (LRR), and variability of R-R intervals. Peak plasma concentrations of verapamil were observed immediately after intravenous verapamil (mean elimination half-life of 3.3 h) and 1 hour after oral verapamil (mean elimination half-life 3.4 h, 80 mg; 3.1 h, 160 mg). In contrast to previous studies, we observed the maximum bradycardic effect of intravenous verapamil to occur at one-half to 1 h, and this effect lasted for 2-4 h. Following oral verapamil the peak effect occurred at 3-4 h and lasted for 5-8 h. Analysis of the time course of changes in APR, SRR, LRR, and variability of R-R revealed two distinct "patterns" of ventricular response. In one group (4 of 8 patients), verapamil caused an increase in SRR but a decrease in LRR. R-R intervals "regularized" in this group. In the remaining patients, verapamil increased the SRR but did not change or increase the LRR. This enhanced the observed increase in ARR intervals. We postulate that the decrease in LRR intervals after verapamil is due to reflex adrenergic discharge as a result of the vasodilator effect of the drug while the increase in SRR is a direct effect. These two opposing effects result in regularization of R-R intervals in many patients. Patients demonstrating an increase in LRR intervals after verapamil may not get reflex adrenergic discharge or may be incapable of responding to the latter due to conduction disease; these patients may experience bradycardic complications after verapamil.

Changes in pacing threshold and R wave amplitude after transvenous catheter countershock.

Transvenous electrode catheter countershock in patients with recurrent ventricular tachyarrhythmias may be followed by transient bradycardia and require temporary pacing with a catheter. The serial changes in R wave amplitude and stimulation threshold after catheter countershock in 11 halothane-anesthetized open chest dogs ranging in weight from 11.8 to 24 kg were studied. Ventricular fibrillation was electrically induced and followed by catheter defibrillation using nonsynchronized trapezoidal waveform (65% tilt) current discharge in incremental doses (5 to 50 J). Significant decreases in bipolar R wave amplitude (8.3 +/- 1 versus 2 +/- 0.2 mV, p less than 0.001) and increases in stimulation threshold (1 +/- 0.1 versus 2.3 +/- 0.4 V, p less than 0.001) were observed using the countershock catheter 15 seconds after countershock; these changes persisted for up to 10 minutes. To determine whether these changes were localized to the defibrillating catheter and whether they were species-specific, a second electrode catheter was positioned in the right ventricle distant from the countershock catheter in five pigs. Increases in stimulation threshold were observed only at the countershock catheter, suggesting that changes were secondary to local changes at the catheter-myocardium interface. No significant change in R wave amplitude or stimulation threshold was observed at the countershock catheter in three pigs given transthoracic shocks (60 to 250 J). It is concluded that current discharge through the countershock catheter results in a significant temporary reduction in R wave amplitude and an increase in pacing threshold. This may make pacing through the countershock catheter unreliable after shock delivery.

Atrial fibrillation: minimal sampling interval to estimate average rate.

The average heart rate and maximal heart rate (average R-R and shortest R-R intervals) in atrial fibrillation are frequently calculated to assess drug effect. The minimum recording sample to obtain accurate estimates of "instantaneous" average and maximum heart rate has not been established. We analyzed the R-R intervals after a 4 minute ECG recording in 40 supine patients with chronic atrial fibrillation. A "life table" analysis revealed that the average heart rate derived from a 20 second sample of atrial fibrillation approximates (+/- 5%) the true value in an estimated 92.5% of patients. On the other hand, a two minute sample is required to approximate the shortest R-R interval within 5% of the true value in 90% of patients. Studies utilizing average R-R interval and shortest R-R interval as an index of drug response should use electrocardiographic sampling intervals of at least 30 seconds and two minutes respectively.

Development of cardiorespiratory function in circumpubertal boys: a longitudinal study.

To investigate cardiorespiratory function during circumpubertal growth, 62 boys (aged 9-10 yr) were studied annually for 6 yr. Measurements of O2 uptake (VO2), cardiac output, and arteriovenous O2 difference were made during a submaximal bicycle test. Values were interpolated to a heart rate of 155 beats X min-1 (VO2 at a heart rate of 155) for comparisons across ages 10.8-14.8 yr. To account for growth differences among the boys, data were also aligned at yearly intervals relative to their individual age of peak height velocity (PHV; maturative age). The group was further divided into early, mid, and late maturers based on their year of PHV. VO2 and stroke volume (SV) of late maturers were larger at each maturative age. SV mirrored the increase in VO2 at all stages of development except during the period of most rapid growth. Arteriovenous O2 difference showed an increase in the year of peak growth with little change during any of the other maturative age intervals. Multiple regression analysis indicated that VO2 was determined primarily by the size of SV throughout this age range.

Blood pressure control in hypertensives--a model for the study of life events.

Life events were elicited during an average recall period of 8.5 months among 235 hypertensive patients whose blood pressure was under control just prior to the beginning of the recall period. At the end of the recall period, the 41 patients no longer under control reported a significantly higher proportion both of unfavourable and unexpected life changes compared with the 194 patients whose blood pressure was still under control. The differences persisted after allowing for potentially confounding variables. The patients were not aware of their blood pressure status at the time of the life events interview.

Sexual and socioeconomic factors affecting the risk of past infections with herpes simplex virus type 2.

Between November 1978 and May 1980, a cross-sectional survey of 566 females and 391 males, aged 35 to 50 years, living in metropolitan Toronto, was conducted to examine the influence of socioeconomic status and sexual behavior on the occurrence of antibodies to herpes simplex virus type 2. Antibodies to the virus were detected in 17.5% of females and 12.8% of males. Lower socioeconomic status was associated with an increased risk of herpes simplex virus type 2 seropositivity for females but not for males. An increased risk of seropositivity was associated in both sexes with young age at first intercourse, multiple sexual partners, and renting rather than owning their residence. The risk associated with each of these attributes remained when the effects of the other attributes including socioeconomic status and age at interview were controlled. The greatest risk was associated with renting. If the renting effect is real, it suggests that there is some determinant of risk not measured by this study, which is more important than socioeconomic status or sexual behavior.