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Biomedical subjects

G Harari

Publications and source records attributed to G Harari.

At least 37 records · Page 2Linked to original sources
PubMed1997

Exercise blood pressure changes between seasons.

BACKGROUND: Blood pressure (casual and daytime) is higher in winter than it is in summer, and this factor might be partly responsible for the higher cardiovascular mortality in winter. OBJECTIVE: To determine in a prospective study whether there is also a seasonal variation in exercise blood pressure. METHODS: We evaluated the pretest, exercise (five-step treadmill test) and recovery values of systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate of 94 healthy men, aged 20-65 years, during the summer and winter. RESULTS: SBP and DBP values were higher in winter than they were in summer during the resting period immediately before exercise (P = 0.003 and P = 0.07, respectively), and during recovery (both P < 0.0001). Exercise SBP and heart rate values were similar in the two seasons, although exercise DBP was higher in winter than it was in summer (P < 0.0001). The increase in DBP from pretest to stage 3 was 6.5 mmHg in summer and 10.4 mmHg in winter (P = 0.002). After we had controlled for possible confounders, the increase in DBP during exercise was found to be independently associated with season of the year and resting DBP. CONCLUSIONS: Exercise DBP varies according to season whereas exercise SBP does not. Our results suggest that, since measures of the response of blood pressure to exercise testing are frequently used in blood pressure and hypertension research as well as in clinical practice, the seasonal influences should be taken into account.

Journal Article↗
PubMed1997

Seasonal differences in blood cell parameters and the association with cigarette smoking.

Seasonal changes in red cell parameters need to be defined in order to properly interpret laboratory results. In this study blood counts were obtained prospectively in 104 healthy men (84 non-smokers and 20 smokers) aged 28-63 years during the summer and winter months. Seasonal changes in plasma volume were also calculated. In healthy non-smokers, their haemoglobin concentration and haematocrit ratio were lower in summer than in winter with a concomitant 5.5% increase in plasma volume. In smokers, there was no change in plasma volume, but haematocrit levels increased in summer. We conclude that both smoking status and seasonal variation should be taken into account in the evaluation of blood count results. Further studies are warranted to determine if our results can be extrapolated to subjects of both sexes and of various ages exposed to different climatic conditions.

Adult↗
PubMed1996

Body mass index is associated with differential seasonal change in ambulatory blood pressure levels.

Seasonal changes in blood pressure may be partially explained in thermoregulatory terms. We hypothesized that the seasonal variation in blood pressure is related to body mass index, due to the increased thermoregulatory requirements of leaner individuals. Ambulatory systolic and diastolic blood pressure were monitored once each in summer and winter in 101 healthy normotensive men aged 28 to 63 years. Environmental conditions and body mass index were measured. The population was divided according to quartiles of body mass index. The percentage of subjects with systolic blood pressure increases of more than 10 mm Hg from summer to winter was highest among subjects in the lowest body mass index category, and lowest among those in the highest body mass index category (35% and 8%, respectively, P < .0001). After adjusting for possible confounders, the change in mean systolic blood pressure from summer to winter was inversely associated with body mass index (beta = -0.26, P = .0149). There was no association between diastolic blood pressure change and body mass index. The increase in systolic blood pressure from summer to winter is inversely and independently associated with body mass index. Hypertension research and epidemiological blood pressure studies should take into account the interaction between season, body mass index, and blood pressure. It may also be important to assess hypertension and response to antihypertensive treatment in relation to season, particularly in lean hypertensives.

Adult↗
PubMed1996

Fatigue among Israeli industrial employees.

We examined the prevalence of fatigue and its association with occupational conditions and health-related habits in 3785 industrial employees of six industrial sectors to define modifiable factors. The factors examined included complaints of fatigue during and after work, an ergonomic evaluation of employees' workstations, demographic characteristics, and health-related habits. Eighteen percent of the subjects complained of severe fatigue frequently or very frequently. We were able to identify two major modifiable variables that were independently associated with the presence of fatigue. Logistic regression showed that those workers who did not participate in physical activity at least once a week had a 1.7-fold increase in prevalence of severe fatigue (95% confidence interval = 1.3 to 2.3, P < 0.001). The other major modifiable factor was temperature control, with those workers who worked at non-temperature-controlled workstations having a 50% increase in the prevalence of fatigue (odds ratio = 1.5, 95% CI = 1.1 to 2.1; P = 0.01). Accidents were significantly more frequent in those workers with fatigue. Further studies should focus on intervention programs to modify the factors identified by this study.

Adult↗
PubMed1996

Summer-winter variation in 24 h ambulatory blood pressure.

OBJECTIVE: To examine possible seasonal differences in circadian blood pressure patterns and the specific contribution of indoor temperature. METHOD: Twenty-four-hour ambulatory systolic blood pressure (SBP) and diastolic blood pressure (DBP) were monitored once in summer and once in winter in 101 healthy subjects aged 28-63 years. Subjects were interviewed concerning health-related habits, and measurements of environmental and occupational conditions were obtained. RESULTS: After controlling for possible confounders, mean SBP during work was significantly higher in winter than in summer by 3.4 mmHg. Both in winter and in summer, the highest values were recorded during work. The daily SBP circadian amplitude was higher in winter, reflected by higher mean SBP during the day and lower mean SBP at night. All of the daytime DBP measurements were higher in winter than in summer, but at night there were no seasonal differences. The blood pressure showed an independent association with season and with environmental temperature (SBP) beta = 3.98 mmHg and -1.14 mmHg/ degrees C, respectively; DBP beta =4.39 mmHg and -0.58 mmHg/ degrees C, respectively).CONCLUSION: In healthy men, the daily amplitude of ambulatory blood pressure varies physiologically by season with the highest values being obtained during work time in the winter months. If these results can be extrapolated to hypertensives then it might be necessary to tailor drug therapy to these variations. The daily average or clinical measurements may lead to an underestimation of the extent of the seasonal variation in blood pressure. The season of the year must be controlled for in clinical and epidemiological studies comparing blood pressure levels and amplitudes between groups or between baseline and follow-up study.

Journal Article↗
PubMed1995

A prospective study of the effects of changes in smoking habits on blood count, serum lipids and lipoproteins, body weight and blood pressure in occupationally active men. The Israeli CORDIS Study.

In cross-sectional studies, significant differences in cardiovascular disease risk factors have been observed between smokers and non-smokers. The aim of this study was to examine the effects of smoking initiation and cessation on these factors in a population-based prospective study. 987 male employees in Israeli industry underwent health screening in the CORDIS study and were re-examined an average of two and a half years later. We examined the associations between smoking initiation and cessation and changes in blood count, serum lipids and lipoproteins, body weight and blood pressure. After adjusting for potential confounders, smoking cessation was associated with significant decreases in leukocyte count, hemoglobin and hematocrit whereas smoking initiation resulted in increased leukocyte count. There were moderate, non-significant increases in both serum HDL cholesterol (HDL-C) and LDL-C, and a slight decrease in serum triglycerides. Blood pressure remained essentially unchanged, despite the fact that smoking cessation resulted in a significant weight increase and smoking initiation in a significant decline in weight. These findings demonstrate that changes in smoking habits result in fairly rapid changes in blood count and body weight, but have much smaller effects on serum lipids and blood pressure.

Adult↗
PubMed1995

Seasonal changes in ambulatory blood pressure in employees under different indoor temperatures.

OBJECTIVE: The effect of indoor temperature control on summer and winter ambulatory blood pressure levels at work was studied. METHOD: Ambulatory systolic blood pressure (SBP) and diastolic blood pressure (DBP) were monitored once in summer and once in winter in 101 healthy normotensive subjects aged 28-63 years, engaged in similar physical work, from two plants with and three without air conditioning. Subjects were interviewed about health related habits, and measurements of environmental and occupational conditions were obtained. RESULTS: After controlling for possible confounders, mean SBP and DBP during work were significantly higher in winter than in summer (delta SBP = 3.4 mm Hg, P = 0.035; delta DBP = 3.3 mm Hg, P < 0.003). The seasonal change in SBP and DBP showed an independent association with the presence or absence of air conditioning of the industrial plants (SBP: beta = 0.194, P < 0.0001; DBP: beta = 0.054, P = 0.038). The percentage of subjects with increases of more than 10 mm Hg from summer to winter was higher in plants without than with air conditioning. CONCLUSIONS: (1) In normotensive subjects ambulatory working BP varies by season, with higher values in winter. If validated for hypertensive subjects, it may be necessary to tailor drug treatment to these variations. (2) The findings make it clear that drawing valid conclusions from comparisons of BPs between groups requires controlling for several factors, particularly season of the year. (3) Climatic conditions in the industrial plant influence the magnitude of seasonal variations in BP. Work in plants without air conditioning places a considerable added load on the employee's cardiovascular system.

Adult↗
PubMed1995

Factors affecting differences in supine, sitting, and standing heart rate: the Israeli CORDIS Study.

BACKGROUND: Measuring postural changes is among the simplest methods to elicit basic cardiovascular responses from patients who should not be subjected to treadmill stress testing. We attempted to clarify the individual factors that may affect these changes in resting heart rate (HR). METHODS: In a cross-sectional study, 6016 employees in Israeli industries were screened during 1985-87 for cardiovascular disease risk factors (The CORDIS Study). Measures of resting HR (supine, sitting, and standing) were obtained from 5428 subjects. The association between the HR differences for different postures and age, sex, height, body mass index, blood pressure level, health related habits, environmental temperature, and time of the day was analyzed. RESULTS: The difference in HR between supine and standing position was found to be greater among women than men (12.7 vs. 11.6%, p < 0.03). It was independently positively associated with height (p < 0.0001), cigarette smoking (p < 0.0001), and coffee drinking (p < 0.001), and inversely associated with age (p < 0.002), blood pressure level (p < 0.0005), and physical activity at work (p < 0.0001). CONCLUSION: The interindividual variability in HR response to different postures is partially explained by individual variables such as age, sex, height, blood pressure level, and health-related habits.

Adult↗
PubMed1994

Serum lipids and haematological factors associated with resting heart rate: the CORDIS Study. Cardiovascular Occupational Risk Factors Detection in Israeli Industries.

OBJECTIVE: We set out to examine the association between resting heart rate and haematological factors and blood lipids, all believed to be associated with coronary heart disease. METHODS: In a cross-sectional study, 6016 industrial employees in Israel were screened between 1985 and 1987 for cardiovascular disease risk factors [the CORDIS Study (Cardiovascular Occupational Risk Factors Detection in Israeli Industries)]. Repeated measures of resting heart rates were obtained. Complete data were available for 5393 participants. The lowest mean measure was used to examine the association with individual factors. RESULTS: For men, of the blood lipids, only triglycerides were independently positively associated with resting heart rate after controlling for all the possible confounding factors (P<0.002). Mean heart rate was higher at elevated triglyceride levels (70 beats/min at < or = 93 mg/dl and 73.3 beats/min at > 150 mg/dl). Platelet count and haemoglobin were independently positively associated with heart rate (P < 0.0001 in both groups). For women, low-density lipoprotein cholesterol and leucocyte count were independently positively associated with resting heart rate (P < 0.05 and P = 0.006, respectively). CONCLUSION: These associations suggest that the role of resting heart rate as a predictor of coronary heart disease may be partly explained by its association with triglycerides, haemoglobin, platelet count and leucocyte count, which may be confounding factors or intervening variables.

Adult↗
PubMed1993

Seasonal changes in red blood cell parameters.

Seasonal changes in blood count (haematocrit and haemoglobin values) have been described in studies of small samples. Since Israel is characterized by high summer temperatures, we attempted to determine whether there are circannual changes in blood count, and how they are influenced by mean monthly temperature. In a cross-sectional study, venous blood was drawn from 4317 male employees in industry aged 20-64 years. Blood count values were analysed by month. To estimate possible changes in serum osmolality, serum electrolytes were also examined. Values of haemoglobin and haematocrit in August were significantly lower than during the rest of the year. Circannual rhythms explained between 10% and 57% of the variances of all the variables as assessed by cosinor rhythmometry, although they had wide confidence intervals and most were not statistically significant. The lower mean haematocrit in August reflected reduction in mean corpuscular volume (MCV) rather than a decrease in red blood cell count (RBC). The change observed in haematocrit and haemoglobin in August is possibly related to heat acclimatization rather than to endogenous sinusoidal circannual rhythms. Both plasma and red cell volume expansion appear to occur. Possible seasonal changes should be taken into account in evaluation of blood counts.

Adult↗
PubMed1993

Circannual variations in blood cholesterol levels.

The seasonality of blood cholesterol is still not well established. Some have described a seasonal pattern with highest levels during autumn and lowest in summer, whereas others have reported no change. A number of studies showed circannual variations with maximum levels in winter and minimum in summer. The aim of this study was to examine the circannual variation of cholesterol in a large cohort in Israel. In the Israeli CORDIS study, employees of 21 factories were screened for cardiovascular disease risk factors during 1985-7. As part of the information gathered, serum cholesterol and blood counts were available for 3,726 men and 1,514 women. Serum cholesterol levels fit a circannual rhythm assessed by the cosinor analysis. Highest levels of serum cholesterol were found in spring and lowest in summer. We conclude that there is a circannual change of serum cholesterol, which could be partially associated with changes in environmental temperature. The circannual variation in serum cholesterol was considerable and should be taken into account when carrying out clinical evaluation of patients.

Adult↗
PubMed1992

Association of serum lipoproteins and health-related habits with coffee and tea consumption in free-living subjects examined in the Israeli CORDIS Study.

BACKGROUND: A positive association between coffee consumption and serum cholesterol levels has been demonstrated and recent results indicate that this may be due to a lipid-rich fraction present mainly in boiled coffee. The possible effects of tea consumption are less clear, although evidence has been presented which suggests that tea drinkers have lower cholesterol levels. The associations between serum lipids and lipoproteins and coffee and tea consumption were examined in the Israel CORDIS study. METHODS: Employees of 21 factories were screened for cardiovascular disease risk factors between 1985 and 1987. Detailed data on coffee and tea consumption and serum lipids and lipoproteins were available for 3,858 men and 1,511 women. RESULTS AND CONCLUSIONS: Consumption of five or more cups of coffee per day was reported by 10.1% of men and 8.7% of women, whereas only 3.4% of men and 2.2% of women consumed similar quantities of tea. After controlling for a number of potential confounders, coffee consumption (particularly "mud" coffee) was strongly and positively associated with higher serum total and low-density lipoprotein cholesterol levels in both sexes (consumers of five or more cups per day had cholesterol levels up to 18 mg/dl higher than abstainers) and with high-density lipoprotein cholesterol in women. There was a nonsignificant negative association between tea consumption and serum cholesterol (cholesterol levels about 5 mg/dl more in abstainers than in those consuming five or more cups per day). In general, more negative health-related habits were reported with increased coffee consumption, whereas this relationship was not found for tea drinking. The relatively small percentage of heavy tea drinkers limits the conclusions that one can draw from this study and controlled trials are needed to evaluate possible lipid-lowering effects of tea consumption.

Adult↗
PubMed1992

Past and present smoking behaviour and its association with health-related habits in selected Israeli working populations. The Cordis Study.

Comprehensive surveys on the characteristics of smokers provide important data for the targeting and monitoring of smoking cessation programmes, and making international comparisons. Current information on this subject in Israel is very limited. During 1985-1987, the prevalence and correlates of cigarette smoking were examined in 5281 employees in Israeli industry, screened in the framework of the CORDIS study. The prevalence of smoking in men ranged from 44.7% in the age group 20-24 years to 28.0% in those aged 55-64. For women the prevalence ranged from 23.2% to 15.0% over the same age range. Ethnic differences were most marked in younger males with the highest prevalence in those of North African origin. Among females, the highest prevalence was among those of Western European origin. In most age groups, the highest proportion of exsmokers was found among those of Eastern European origin, except for older females where differences were not significant. Among males, educational differences were strong, with those of lower education smoking the most, whereas among females no significant differences were observed. For both sexes, past smokers were more prevalent in the highest education category. There was a cohort effect in declining age at starting smoking in both sexes and females tended to start smoking about 2 years older than males. Exsmokers tended to have been heavier smokers than current smokers, suggesting that heavy smokers may be more likely to quit than light smokers.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Industrial noise exposure and ambulatory blood pressure and heart rate.

Studies on the effects of long-term exposure to industrial noise on resting blood pressure have yielded inconsistent results. Ambulatory blood pressure and heart rate were monitored simultaneously with noise exposure in normotensive male industrial workers in Israel (85 aged 25 to 44 and 77 aged 45 to 65 years). In the younger group, average ambulatory systolic blood pressure was 3.2 mm Hg higher and diastolic blood pressure 2.3 mm Hg higher in subjects exposed to more than 85 dBa (P less than .001), after adjusting for potential confounding variables. In those aged 45 to 65, ambulatory systolic blood pressure was 3.3 mm Hg lower and diastolic blood pressure unchanged in noise-exposed subjects. Ambulatory heart rate was 2.7 and 2.6 beats per minute higher at the higher noise level (P = .002) in the respective age groups. These findings suggest that industrial noise exposure is associated with higher ambulatory blood pressure and heart rates in men under 45 years old, but the effect on blood pressure appears to diminish considerably with age.

Adult↗
PubMed1977

[Gentamycin in distributive balance between serum, perilymph and liquor in guinea-pig after dosage in therapeutical range (author's transl)].

Dosage of gentamycin in therapeutical range just as in higher doses results in a distributive balance between serum, perilymph and liquor under the condition of steady serum levels. After high doses the perilymph levels compared to the serum levels are relatively lower than after less doses. The distributive balance is reached after about 7 h in doses, which lead to concentrations of the serum levels of the supposed ototoxic critical range. Afterwards the concentration in the inner ear doesn't increase. In steady state, the concentration in serum is always higher than in perilymph, whereas the perilymph concentration is always higher than the one in liquor.

Animals↗
PubMedDate not supplied

Acute and chronic effects of noise exposure on blood pressure and heart rate among industrial employees: the Cordis Study.

The effects of industrial noise on resting heart rate and blood pressure were studied in 3,105 blue-collar workers. Heart rate and blood pressure were measured in different workers at various times during the workday. After controlling for several possible confounders, we found that resting heart rate in females was associated positively with noise intensity (p = .036) and with time of day (p = .054). In males, resting heart rate was associated with noise intensity; however, such association was related to time of day (p = .046). No such associations were found for blood pressure in either sex. We plotted the mean resting heart rate by time of day for workers exposed to high [ > or = 80 db(A)] and low noise, and no difference was evident with respect to morning heart rate in either sex. After 4 h of noise exposure for males (and less time for females), individuals who were exposed to high noise had higher heart rates; however, in females this was not observed at the end of the workday. Thus, recurrent daily exposure to high noise at work has an acute, though not residual, effect on resting heart rate.

Adult↗
PubMedDate not supplied

Type A behavior, tension, and ambulatory cardiovascular reactivity in workers exposed to noise stress.

Recent negative findings regarding differences in blood pressure (BP) and heart rate (HR) reactivity at work between Type A and Type B workers may stem from the failure to note the stressors to which they were exposed. In this naturalistic study, an objective work stressor--varying levels of ambient noise--was individually monitored among 123 normotensive males. We examined the relationship of Type A behavior (assessed by the Thurstone Temperament Schedule) to ambulatory BP and HR reactivity under high and low noise conditions. We also tested the hypothesized mediating function of tension arousal. Results of multiple regression analyses indicated that when workers were exposed to high noise levels (> or = 80 dB(A)), Type A behavior was positively related to diastolic BP (p = 0.029) and HR reactivity (p = 0.0001), even after adjusting for clinic values, time of measurement, worker activities, and body position during measurement. When the same workers were exposed to low noise levels, the results were not significant. This suggests that noise constitutes a stressor for Type A individuals, and highlights the importance of noting the actual stressor-exposure condition. In addition, Type A individuals reported high tension, noted concurrently with the ambulatory measurements. Tension arousal was also related to BP and HR reactivity. Adding the tension variable to the above regressions weakened the relationship between Type A behavior and BP and HR reactivity. Thus, the tension experienced by Type A workers exposed to noise stress may have served as a mediator of cardiovascular reactivity.

Adult↗