Israel Medical Association Journal

Background: High levels of plasma homocysteine constitute a risk for cardiovascular disease. Physical activity, known to reduce CVD[1] risk, has been related to levels of Hcy[2]. Recently, higher Hcy was shown to be associated with lower cardiovascular fitness in women but not in men.

Objectives: To further explore the relationship between cardiorespiratory fitness and plasma total homocysteine levels in a large cohort of adult males and females.

Methods: This cross-sectional study included 2576 fitness and Hcy examinations in adults (62% males) aged 30–59 years, randomly drawn from a population undergoing a periodic health examination in the Sheba Medical Center's Executive Screening Survey. Blood tests were collected for tHcy[3] and a sub-maximal exercise test was performed to estimate cardiorespiratory fitness. Information on CVD/CVD risk factors (coronary heart disease, cerebrovascular accident, diabetes, hypertension or dyslipidemia) was self-reported.

Results: Mean tHcy plasma levels were 14.4 ± 7.7 and 10.2 ± 3.0 µmol/ml, and mean maximal oxygen uptake 36.5 ± 11.7 and 29 2 ± 9.5 ml/kg/min for males and females, respectively. A multiple regression analysis, adjusting for age, body mass index and CVD/CVD risk factors, showed no association between cardiorespiratory fitness and level of tHcy in males (P = 0.09) or in females (P = 0.62).

Conclusions: In this sample no relationship was found between level of cardiorespiratory fitness and plasma tHcy in men or women. The inconsistency of findings and the small number of studies warrant further research of the association between cardiorespiratory fitness and tHcy, an association that may have clinical implications for the modifications of cardiovascular risk factors.

Background: Endothelial dysfunction is recognized as a major factor in the development of atherosclerosis and it has a prognostic value.

Objectives: To detect the long-term association of peripheral vascular endothelial function and clinical outcome in healthy subjects and patients with cardiovascular disease.

Methods: We prospectively assessed brachial artery flow-mediated dilation in 110 consecutive subjects (46 CVD[1] patients and 64 healthy controls), mean age 57 ± 11 years; 68 were men. After an overnight fast and discontinuation of all medications for ≥ 12 hours, percent improvement in FMD and nitroglycerin-mediated vasodilatation were assessed using high resolution ultrasound.

Results: %FMD[2] but not %NTG[3] was significantly lower in CVD patients (9.5 ± 8.0% vs. 13.5 ± 8.0%, P = 0.012) compared to healthy controls (13.4 ± 8.0% vs. 16.7 ± 11.0%, P = 0.084; respectively). In addition, an inverse correlation between %FMD and the number of traditional CVD risk factors was found among all study participants (r = -0.23, P = 0.015) and healthy controls (r = -0.23, P = 0.036). In a mean follow-up of 15 ± 2 months, the composite CVD endpoints (all-cause mortality, myocardial infarction, hospitalization for heart failure or angina pectoris, stroke, coronary artery bypass grafting and percutaneous coronary interventions) were significantly more common in subjects with FMD < 6% compared to subjects with FMD > 6% (33.3% vs. 12.1%, P < 0.03, respectively).
Conclusions: Thus, brachial artery %FMD provides important prognostic information in addition to that derived from traditional risk factor assessment

Background: Iodine intake is necessary to maintain normal thyroid function and prevent iodine deficiency disorders. In 1990, a resolution calling for universal salt iodination to eliminate iodine deficiency worldwide was taken by the World Health Organization and endorsed by some 130 countries. As of today, very little is known about iodine intake and the prevalence of iodine deficiency disorders in Israel, and iodine enrichment of regular salt has not been authorized.

Objectives: To assess the current level of iodine intake in an unselected group of residents from the Israeli costal area.

Methods: Spot urine samples were collected from three groups: Group A comprising 51 pregnant women attending the Women s Health Clinic at our institution, with a mean age of 32 years and at gestational week 28; group B consisting of 35 healthy subjects, mean age 38; and group C consisting of 16 euthyroid subjects harboring nodular goiters. Tap drinking and mineral water were also analyzed for iodine content. Iodine concentration was measured using the catalytic reduction of ceric ammonium sulfate method.

Results: When considering all groups together the median urinary iodine concentration was 143 µg/L, with 27% of the study population having concentrations under 100 µg/L and 7.8% under 50 µg/L. Values were distributed similarly between sites of residency, and no significant differences were seen between groups. The mean iodine concentration for tap drinking water was 22.8 µg/L (range 0.5–53.5 µg/L) and for mineral water 7 µg/L (range 0–15 µg/L).

Conclusions: Overall, iodine intake appeared to be satisfactory in our study population, however mild deficiency may exist in up to 26% of this group. A nationwide survey is needed to better determine the status of iodine intake in Israel, allowing for recommendations on salt-iodine enrichment in the future.

Background: A high total plasma homocysteine level is an independent risk factor for cardiovascular and cerebrovascular disease, but the evidence connecting plasma tHcy level with hypertension is inconsistent.

Objective: To determine the association between plasma tHcy level and some common risk factors for cerebrovascular disease (recurrent  stroke, diabetes mellitus, hypertension, ischemic heart disease and hyperlipidemia) in patients presenting with primary or recurrent acute ischemic strokes.

Methods: This retrospective cross-sectional chart analysis was conducted in a university-affiliated referral hospital. During an 18 month period we identified 113 acute ischemic stroke patients (mean age 71.2), 25 of whom had a recurrent stroke. Plasma tHcy[1] level, obtained 2–10 days after stroke onset, was determined by the high performance liquid chromatography method with fluorescence detection. A multivariate logistic regression model was used to determine the independent relationship between each potential risk factor and tHcy level above or below the 75th percentile.

Results:  Hypertension was more frequent among patients with plasma tHcy level above than below the 75th percentile (51.7% vs. 80.8%, respectively, P = 0.012). After adjusting for demographic and clinical variables, the odds ratio for recurrent stroke and hypertension, with tHcy above or below the 75th percentile, was 3.4 (95% confidence interval 1.01–10.4, P = 0.037) and 4.02 (95% CI[2] 1.2–13.9, P = 0.028), respectively.

Conclusions: A high plasma tHcy level is associated with history of hypertension and recurrent stroke among patients presenting with acute ischemic stroke. These results were independent of other risk factors such as atrial fibrillation, diabetes and hyperlipidemia. Hypertensive stroke patients with hyperhomocysteinemia should be identified as high risk patients as compared to non-hypertensive stroke patients, and may warrant more vigorous measures for secondary prevention.

Background: Case-control and prospective studies indicate that an elevated plasma homocysteine level is a powerful risk factor for atherosclerotic vascular diseases. Certain medications can induce hyperhomocystinemia, such as methotrexate, trimethoprim and anti-epileptic drugs. There are few reports indicating an interaction between lipid-lowering drugs (cholestyramine and niacin) and homocysteine. Recently, an interaction was shown between fenofibrate and benzafibrates (a fibric acid derivative) and homocysteine plasma levels.

Objectives: To evaluate the effects of different fibrates on plasma homocysteine levels and to measure the reversibility of this effect.

Methods and Results: We investigated the effects of ciprofibrate and bezafibrate on homocysteine levels in patients with type IV hyperlipidemia and/or low high density lipoprotein levels. While a 57% increase in homocysteine was detected in the ciprofibrate-treated group (n=26), a 17% reduction n homocysteine was detected in the group treated with bezafibrate (n=12). The increase in homocysteine in the ciprofibrate-treated group was sustained for the 12 weeks of treatment and was partially reversible after 6 weeks of discontinuing the ciprofibrate therapy.

Conclusions: These results indicate that an increase In plasma homocysteine levels following administration of flbrates is not a class effect, at least in its magnitude. Moreover, it is reversible upon discontinuation of the treatment.
 

Background: Most corneal damage induced by contact lenses is due to interference with corneal oxygenation.

Objective: To investigate the effect on the rabbit cornea of a rigid gas-permeable contact lens with a newly designed periphery.

Method: We fitted New Zealand white rabbits (n=12) with RGP[1] contact lenses that were identical in all respects except for the design of the periphery. In each animal, one contact lens had an innovative periphery consisting of a microscopic diffractive relief lathed on the back surface; the other contact lens was of a conventional design. The lenses were worn continuously for 7 days. During this experimental period and for 1 additional week we assessed the corneal damage by daily testing lactic dehydrogenase activity in the tears.

Results: On the last day of the experimental week and the first 3 days of the healing period, mean tear LDH[2] activity was significantly lower in the eyes with the new contact lens design than in eyes with the conventional lenses.

Conclusions: The novel periphery design reduces corneal damage resulting from contact lens wear, as reflected by LDH levels in the tears. The new design probably facilitates the flow and exchange of tears under the contact lens, resulting in improved metabolism of the cornea. These findings may also prove applicable to soft contact lenses.