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Biomedical subjects

A Shamiss

Publications and source records attributed to A Shamiss.

At least 19 recordsLinked to original sources
PubMed2001

Dietary electrolytes and hypertension in the elderly.

The effect of age on older hypertensive patient's blood pressure response to increased sodium intake is well known. Salt sensitivity which does increase with age and the decrease in renal function limiting the ability of aged kidney to excrete sodium load are major factors, responsible for rise in blood pressure during Na consumption in the elderly. Clinical studies encourage salt reduction with and without weight loss. Although potassium consumption is highly recommended, one should be aware of potassium overload in the elderly.

Aged↗
PubMed1999

The relationship of physical fitness on pilot candidate selection in the Israel Air Force.

BACKGROUND: The purpose of this study was to examine whether physical fitness is an important component in the selection process of pilot candidates to the Israel Air Force (IAF) flight school. METHODS: There were 223 male pilot candidates who volunteered to participate in the study. All subjects were tested 1 - 12 wk prior to a week-long "bootcamp" for aerobic power (Astrand bicycle test), anaerobic power (vertical jump test), and percent body fat. In addition, an activity profile was established based on an activity history questionnaire. All fitness measures were correlated to a performance score based on the IAF selection criteria measure for each candidate. RESULTS: Candidates who were accepted to flight school had a higher aerobic capacity, anaerobic power output relative to body weight and a lower percent body fat than candidates who were not successful. Significant correlations were seen between the performance score and aerobic power (r = 0.31), anaerobic power (r = 0.17) and anaerobic power relative to body weight (r = 0.21). Linear regression analysis showed that aerobic power explained 9% of the variance in the performance score, while anaerobic power explained an additional 3%. The results of this study suggest that physical fitness has a positive influence on the success of pilot candidates in gaining admittance to the IAF flight school.

Aerospace Medicine↗
PubMed1996

Effects of high gravity on cardiac dimensions in trained air crew.

We conclude that there is no difference in LV wall thickness, dimensions, or functional parameters between air crew members who fly high + Gz aircraft and those who fly other types of aircraft. No differences were detected between high +Gz air crew personnel and others in development of structural and functional changes over the short-term course of a flying career.

Adult↗
PubMed1996

Felodipine in the treatment of severe refractory hypertension.

The efficacy of felodipine and tolerance of this drug was examined in 52 patients, 23 men and 29 women, 18-76 years of age, in whom it either replaced previous therapies of nifedipine and other vasodilators, or was added to a constant dose of beta blockers and diuretics or another previous therapy, which was unchanged. Felodipine significantly reduced blood pressure (BP), from 192.3 +/- 31.9/114.3 +/- 18.0 to 155.7 +/- 19.5/93.8 +/- 11.5 mm Hg, with no change in pulse rate. There were no significant biochemical changes, renal deterioration or blood sugar disequilibrium. Adverse reactions including flushes and leg edema could be tolerated by most of the patients, however six patients dropped out. Orthostasis dictated a decrease in felodipine dosage. Felodipine appears to be a highly potent, well tolerated drug and offers a substitute treatment for severe hypertensives refractory to other vasodilators.

Adolescent↗
PubMed1996

Stapedectomy in combat pilots.

Between 1977 and 1995, nine stapedectomies using the Robinson-vein graft technique were performed in six high-performance airplane pilots diagnosed with otosclerosis. All of them returned to full active duty after stapedectomy without any vestibular symptoms. These cases illustrate that it can be safe for fighter or test pilots to return to full flight status after stapedectomy. These cases also suggest that full flight status can be reinstated as soon as 3 months after stapedectomy without endangering flight safety.

Aviation↗
PubMed1996

Mefloquine versus doxycycline for malaria prophylaxis in intermittent exposure of Israeli Air Force aircrew in Rwanda.

BACKGROUND: The issue of the best chemoprophylaxis agent for aircrew to use against malaria is still not settled. METHOD: We studied the patterns of use of both doxycycline and mefloquine in aviators and other aircrew for 2 mo during biweekly flights from Israel to Rwanda with a few hours' visits. Some 28 aviators and 15 non-aviator aircrew were treated with doxycycline and mefloquine, respectively, less than 12 h before the first flight and up to 4 wk after the last return. RESULTS: No case of malaria occurred within or after the operational period. Compliance was better for mefloquine than for doxycyline for the full period of the operation (100% vs. 75%, respectively). The rate of side effects, mostly gastrointestinal, was higher for doxycycline (39% vs. 13%, respectively) and was related mainly to the frequency of administration (daily vs. weekly). CONCLUSION: In situations involving frequent intermittent short-term visits to areas with substantial risk of acquiring malaria, we conclude that aircrew can safely take weekly mefloquine as prophylaxis.

Aerospace Medicine↗
PubMed1995

The effect of enalapril with and without hydrochlorothiazide on insulin sensitivity and other metabolic abnormalities of hypertensive patients with NIDDM.

The effect of 20 mg of enalapril with and without 12.5 mg of hydrochlorothiazide on glucose metabolism insulin sensitivity and lipids was evaluated in hypertensive non-insulin-dependent diabetes. Ten mild to moderate hypertensive patients with non-insulin-dependent diabetes mellitus were treated for 8 weeks with 20 mg enalapril once a day, and then divided into two groups of 5 patients each for a second 8 weeks of treatment with enalapril alone or in combination with hydrochlorothiazide, 12.5 mg once a day. Blood pressure, fasting plasma glucose, lipids and insulin, glycosylated hemoglobin, and insulin sensitivity were measured at baseline and after 8 and 16 weeks. Results were analyzed by the ANOVA test for repeated measures and all values are given as mean +/- SD. Diastolic blood pressure decreased significantly after the first and second period of enalapril and after the combination of enalapril and hydrochlorothiazide. Glycosylated hemoglobin dropped significantly after the first and second period of enalapril monotherapy. Plasma triglycerides and fasting plasma insulin decreased significantly after the 16 weeks of enalapril. Insulin-mediated glucose uptake increased significantly after 8 and 16 weeks of monotherapy with enalapril. No significant difference was observed in any of the metabolic characteristics, including insulin sensitivity, between the values after 8 weeks of enalapril alone and the final values of the enalapril-treated and the enalapril/hydrochlorothiazide-treated groups. It is concluded that enalapril improves some of the metabolic parameters, including insulin sensitivity, of hypertensive diabetic patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Twenty-four-hour blood pressure monitoring during treatment with extended-release felodipine versus slow-release nifedipine: cross-over study.

The lack of comparative studies of nifedipine and felodipine using 24-h blood pressure (BP) monitoring in the same patients led to the present study evaluating the antihypertensive efficacy and side effects of treatment with slow-release (SR) nifedipine (20 mg twice daily) and extended-release (ER) felodipine (10 mg once daily). In the double-blind study, subjects were randomly assigned to one of two treatment groups: 6 weeks of nifedipine SR (20 mg twice daily) followed by 6 weeks of felodipine (ER) (10 mg once daily with evening matched placebo), or vice versa. Twenty-four-hour ambulatory BP monitoring showed no significant differences in systolic BP (SBP) during the day. There were no significant differences in diastolic BP (DBP) throughout the 24 h, although the frequency of DBP recordings > 90 mm Hg was greater during nifedipine (33.1%) than felodipine (27.75%) treatment. The most common side effects were flushing, palpitations, headaches, and ankle edema; there were no adverse effect on lipid profile or glucose level.

Adolescent↗
PubMed1995

Altered circadian rhythm of blood pressure in shift workers.

The effect of shift work on the circadian rhythm of blood pressure (BP) was studied in male bakery workers. The study group consisted of 28 men, blue collar non-rotating shift workers, 20-60 years of age, and the control group comprised 30 men, blue collar, day workers in the same age group. BP was evaluated in all subjects by 24h BP monitoring. Day workers showed typical circadian rhythm with a drop in both systolic and diastolic BP at night. This pattern was reversed in night workers. The peak SBP for night workers was at 11 pm and among day workers at 4 pm. Peak DBP was recorded among night workers at 10 pm and among day workers at 3 pm. All subjects showed a highly significant cyclic variation in BP. Whereas the range for SBP was similar in these two age groups (P > 0.05), the amplitude of DBP tended to be smaller in young workers. Therapeutic decisions for night shift workers with hypertension should take into account their altered BP cycle.

Adult↗
PubMed1994

Hemodynamic and humoral effects of the angiotensin II antagonist losartan in essential hypertension.

Losartan (DuP 753) is a novel orally active angiotensin II antagonist that lowers blood pressure. The present study evaluates the hemodynamic and humoral effects of losartan in essential hypertension. Fifteen patients (12 men, 3 women; mean age, 46 +/- 2 years; range, 33 to 64 years) with a diastolic blood pressure (DBP) between 95 and 115 mm Hg after 2 weeks of placebo participated in the study. Initially the patients were treated with losartan (50 mg) once daily for 1 month. Then, if the trough DBP was > or = 93 mm Hg, hydrochlorothiazide (HCTZ), 6.25 to 12.5 mg daily, and nifedipine, 30 to 60 mg daily, were added as needed. Ten patients completed 12 months of treatment. Trough blood pressure, heart rate, plasma creatinine, potassium, uric acid, cholesterol, renin activity (PRA), aldosterone, and norepinephrine were measured at baseline and after 1 and 12 months of treatment. Losartan lowered mean arterial pressure significantly from 119 +/- 2 mm Hg at baseline to 113 +/- 2 mm Hg (P < .05) after 1 month of treatment. Coadministration of HCTZ and nifedipine further decreased the mean arterial pressure to 103 +/- 2 mm Hg after 12 months of treatment. Plasma levels of creatinine, potassium, uric acid, cholesterol, and norepinephrine remained unchanged. PRA increased and plasma aldosterone decreased significantly (P < .05). The decrease in mean arterial pressure was related to baseline PRA (r = 0.53, P < .05). and to the change in PRA (r = 0.52, P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Clinical pharmacokinetics of ramipril.

Ramipril is a long-acting nonsulfhydryl angiotensin converting enzyme (ACE) inhibitor introduced for clinical use about a decade ago. Ramipril is a prodrug that undergoes de-esterification in the liver to form ramiprilat, its active metabolite. Ramipril rapidly distributes to all tissues, with the liver, kidneys and lungs showing markedly higher concentrations of the drug than the blood. After absorption from the gastrointestinal tract, rapid hydrolysis of ramipril occurs in the liver. In the therapeutic concentration range, protein binding of ramipril and ramiprilat is 73 and 56%, respectively. Ramiprilat binds to ACE with high affinity at concentrations similar to that of the enzyme and establishes equilibrium slowly. Although ramipril is metabolised by hepatic and renal mechanisms to both a glucuronate conjugate and a diketopiperazine derivative, most of the drug is excreted in the urine as ramiprilat and the glucuronate conjugate of ramiprilat. Elimination from the body is characterised by a relatively rapid initial phase with a half-life of 7 hours and a late phase with a half-life of about 120 hours. No clinically significant pharmacokinetic interactions between ramipril and other drugs have been reported. The drug has been generally well tolerated with the most prevalent adverse effects being dizziness (3.4%), headache (3.2%), weakness (1.9%) and nausea (1.7%). Ramipril is an effective and well tolerated drug for the treatment of hypertension and congestive heart failure in all patients, including those with renal or hepatic dysfunction, and the elderly.

Drug Interactions↗
PubMed1993

The role of atrial natriuretic peptide in the diuretic effect of Ca2+ entry blockers.

The effect of three calcium entry blockers--verapamil, nifedipine and felodipine--on diuresis, natriuresis, the renin-aldosterone axis, and atrial natriuretic peptide (ANP) levels was studied in 30 previously untreated patients with mild to moderate essential hypertension. All three blockers produced significant antihypertensive effects after 2 and after 24 h. Heart rate tended to decrease, but did not change significantly after verapamil, but increased significantly 1-2 h after nifedipine and felodipine. Plasma renin activity (PRA) did not change significantly with any treatment, and plasma aldosterone decreased with all three agents. ANP levels did not change significantly after verapamil, but increased significantly after nifedipine and felodipine. There was a significant positive correlation between the maximal change in ANP level and urinary sodium after nifedipine and felodipine. The increase in urinary sodium after verapamil was not significant. The role of the direct renal effect of calcium entry blockers in their persistent natriuretic action is discussed, as well as their short-term enhancement of ANP levels, which may account for the initial diuretic and natriuretic effects seen with this class of dihydropiridines.

Adult↗
PubMed1993

Acute hypertensive response to +Gz acceleration in mildly hypertensive pilots.

Two fighter pilots with mild hypertension and a mildly hypertensive response to exercise underwent ambulatory blood pressure monitoring during a routine flight that included a brief exposure to +4 Gz stress. They exhibited an acute elevation of both systolic and diastolic blood pressures during +4 Gz stress: from 140/90 and 135/90 mm Hg to 179/139 and 180/140 mm Hg, respectively. Heart rate reached 182 and 132 beats/min. These responses of hypertensives may reflect exaggerated baroreceptor and sympathetic responses which cause a pronounced over-shoot of blood pressure. The findings demonstrate the value of 24-h ambulatory blood pressure monitoring for documenting episodic elevations of blood pressure that do not influence the "normal" average blood pressure, but may nevertheless have important clinical implications.

Acute Disease↗
PubMed1992

Insulin resistance in secondary hypertension.

The insulin sensitivity of five essential hypertensive patients was compared to five patients with renovascular hypertension, five patients with primary hyperaldosteronism, and five normotensive subjects, using the euglycemic hyperinsulinemic clamp technique. Essential hypertensive patients had significantly lower insulin sensitivity than patients with hyperaldosteronism and renovascular hypertensive patients (P = .0066, P = .004, respectively). Hyperaldosteronism patients also had less insulin sensitivity than renovascular hypertensive patients (P = .016). A significant negative correlation was found between body mass index and insulin sensitivity index for essential hypertension patients only (r = -0.87, P less than .003). No such correlation was found in the secondary hypertension patients. The findings suggest a causal relationship between insulin resistance and the development of essential hypertension. Secondary hypertension, on the other hand, is not such an insulin resistant state.

Adult↗
PubMed1992

The role of atrial natriuretic peptide in natriuresis of fasting.

OBJECTIVE: To examine the relation between plasma atrial natriuretic peptide (ANP) and the natriuresis of fasting. DESIGN: ANP, aldosterone and renin were examined during natriuresis of fasting in 25 obese essential hypertensive patients and nine overweight normotensive subjects placed on a supervised 500-KCal diet composed of 50% carbohydrates, 30% fat and 20% protein, and unlimited salt. Twenty-four-hour urinary electrolytes were measured on days 0, 4, 7 and 10 of the diet. RESULTS: Urinary sodium concentration nearly doubled in the patients on day 4, and increased 1.4-fold in the normotensive controls. Plasma ANP rose nearly threefold in the hypertensives on day 4 and nearly doubled in the normotensives. Patients and controls showed similar patterns of natriuresis and ANP secretion during the diet. CONCLUSIONS: We conclude that there is a clear association between ANP levels and natriuresis of fasting.

Adolescent↗
PubMed1992

Left ventricular mass in diabetes-hypertension.

BACKGROUND: This study was undertaken to identify whether diabetes mellitus (DM) accelerates the development of left ventricular hypertrophy (LVH) in hypertensive patients. METHODS: Cardiac structure, systolic function, and hemodynamics were evaluated by two-dimensional M-mode echocardiography in diabetic and nondiabetic patients with essential hypertension. RESULTS: Patients with hypertension with and without DM had the same end-systolic and end-diastolic dimensions, cardiac output, total peripheral resistance, and ejection fraction. Diabetic hypertensive patients had greater interventricular septum (1.32 +/- 0.20 vs 1.07 +/- 0.20 cm) and posterior wall (1.20 +/- 0.20 vs 1.00 +/- 0.10 cm) thickness than did nondiabetic hypertensive patients. Consequently, left ventricular mass index was greater in patients with hypertension and DM than in those without DM (158 +/- 45 vs 113 +/- 20 g/m2). With the use of Devereux criteria for recognition of LVH (left ventricular mass index above 134 g/m2 in men and above 110 g/m2 in women), 72% of the diabetic patients had LVH, whereas only 32% of the nondiabetic patients had LVH. Left ventricular contractility, as reflected by the ratio of end-systolic wall stress to end-systolic volume index, was decreased in diabetic compared with nondiabetic hypertensive patients. CONCLUSIONS: The data suggest that DM accelerates the development of LVH in patients with essential hypertension independent of arterial pressure and, therefore, may contribute to the increased cardiovascular morbidity and mortality in patients with hypertension.

Analysis of Variance↗