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Biomedical subjects

D T Lowenthal

Publications and source records attributed to D T Lowenthal.

At least 19 recordsLinked to original sources
PubMed2001

Effects of resistance training on insulin-like growth factor-I and IGF binding proteins.

PURPOSE: Our goal was to determine the effects resistance training on circulating IGF-I and on two of its major binding proteins, IGFBP-1 and IGFBP-3. Additional goals were to compare the time course of hormonal changes with the time course of strength changes and to determine the effect of training volume on the extent of hormonal changes. METHODS: Thirty-one men and women (mean age = 37 +/- 7 yr) completed a 25-wk, 3 d x wk(-1) program in which they performed single-set resistance training (1-SET, N = 11), multiple-set resistance training (3-SET, N = 11), or no exercise (Control, N = 9). Before training, and after 13 and 25 wk of training, blood hormones were analyzed and strength was assessed as the sum of one-repetition maximum (1-RM) for leg extension and chest press exercises. RESULTS: During the first 13 wk of resistance training, circulating IGF-I increased by approximately 20% in both the 1-SET and 3-SET groups (P = 0.041). No further increases occurred between 13 and 25 wk. In the 3-SET group, IGFBP-3 decreased 20% between 13 and 25 wk (P = 0.008). Training did not alter IGFBP-1. Increases in 1-RM strength occurred mainly during the first 13 wk of training and were significantly higher with 3-SET training compared to 1-SET. CONCLUSIONS: These findings indicate that increased circulating IGF-I may, at least in part, mediate increases in strength that result from resistance training.

Adult↗
PubMed2000

Exercise training in the debilitated aged: strength and functional outcomes.

OBJECTIVE: Resistance and endurance training result in gains in fitness in the aged. It is unclear whether the debilitated elderly can perform moderate-intensity training and whether such training results in short-term improvements in strength, endurance, and function in this population. DESIGN: Randomized, controlled trial. SETTINGS AND PATIENTS: Subjects were from a Veterans Affairs nursing home and rehabilitation unit and a community nursing home. They were older than 60 yrs with impairment in at least one physical activity of daily living. Seventy-eight subjects volunteered and 58 (mean age, 75 yrs; 9 women, 49 men) completed the intervention and initial posttest. Only one subject withdrew because of injury or disinterest. INTERVENTION: Thrice-weekly resistance training (using an isokinetic dynamometer) and twice-weekly endurance training for 4 to 8 weeks. MAIN OUTCOMES: Isometric strength in dominant arm and leg, heart rate response to timed endurance test, and activities of daily living score. RESULTS: The mean change in isometric strength across the muscle movements tested was 32.8% in the training group and 10.2% in the control group (difference, 22.6%; 95% confidence interval, 6.2% to 39.0%). No change in heart rate during exercise was seen in the training group. Trained subjects tended to have a greater improvement in functional activity than control subjects, which was statistically significant (p = .04) for those subjects who at enrollment were most dysfunctional (i.e., activities of daily living score less than 13 [maximum score 26]). CONCLUSION: This group of debilitated elderly patients effectively performed resistance training and increased their strength, with the most impaired gaining the most function. Few in the group could effectively perform endurance training.

Aged↗
PubMed2000

Effects of fosinopril or sustained-release verapamil on blood pressure and serum catecholamine concentrations in elderly hypertensive men.

A randomized, double-blind, placebo-controlled clinical trial showed 14 of 18 (78%) of the elderly hypertensive men in this study had an uncomplicated and beneficial response to either fosinopril or verapamil. There was a well-tolerated reduction in systolic blood pressure (SBP) and diastolic blood pressure (DRP). There were no significant adverse drug events. Only the sitting SBP and the sitting DBP were significantly lowered by fosinopril and verapamil SR. Because reduction in both SBP and DBP in elderly hypertensives has been shown to be beneficial, these findings take on further importance when considering the choice of medication for antihypertensive therapy in the elderly. The increase in norepinephrine in the fosinopril-treated patients may explain why patients treated with long-term angiotensin-converting enzyme inhibitors alone or in combination with diuretics rarely complain of orthostatic symptoms.

Aged↗
PubMed2000

Androgens, anabolic-androgenic steroids, and inhibitors.

Androgens are steroid hormones responsible for male sexual characteristics, testosterone being the principal androgen secreted by the testes. Androgens have both masculinizing and growth-stimulating or anabolic effects. Synthetic analogs of androgens have been used by professional, as well as amateur, athletes for possible performance enhancement. The subject of androgens, pharmacologic actions, organ system effects, therapeutic uses, adverse reactions, and abuse potential are reviewed.

Anabolic Agents↗
PubMed2000

Survival of vascular access during daily and three times a week hemodialysis.

AIM: A major cause of morbidity for hemodialysis patients is vascular access failure and/or occlusion. It is commonly believed that an increased frequency of dialysis sessions, among other factors, might lead to a higher rate of fistula complications. MATERIALS AND METHODS: To evaluate if patients on daily hemodialysis carry a higher risk of vascular access occlusion, we examined the incidence rate of access occlusion and the survival function of native vascular accesses in patients undergoing daily dialysis (DD; n = 24) as compared to patients on standard three times a week hemodialysis (TWD; n = 124). RESULTS: The mean follow-up time was 3.6 years. In the TWD group 42 patients had a first-access closure, whereas only 2 patients out 24 had a similar event in the DD group. The proportion of first-access closure was 33.9% for TWD and 8.3% for DD (p < 0.01). The incidence rate was 9.8 (95% CI: 7.2 -13.2) and 2.2 (95% CI: 0.4 - 7.1) events per 100 patient-years for TWD and DD, respectively. The rate difference was 7.6 (95% CI 3.4 - 11.9) events per 100 patient-years, and the unadjusted risk ratio was 4.5 (95% CI: 1.2 - 16.9; p < 0.01). The mean vascular access survival before closure was 3.3 years in TWD and 3.7 years in DD. Survival curves, obtained considering the first-access closure as the endpoint, showed a significant difference between DD and TWD (log-rank 5.16; p < 0.05). In a Cox-proportional hazard model the relative risk (RR) of vascular-access closure in TWD remained significant (RR = 4.3; 95% CI 1.1 - 18.2) after adjustment for age. CONCLUSION: The results of this observational study, conducted on a limited number of DD patients, suggest that daily dialysis might not have an adverse prognostic significance for access closure.

Arteriovenous Shunt, Surgical↗
PubMed1999

Hypertension in the elderly with coexisting benign prostatic hyperplasia.

The treatment of hypertension in the elderly can be safely achieved with low-dose diuretic therapy. Men with prostatism may benefit from peripheral alpha-blocking drugs. However, drugs such as doxazosin or terazosin may further lower blood pressure and at times may be associated with orthostatic hypotension, especially if diuretics are given concomitantly. Tamsulosin achieves relaxation of the smooth muscle of the prostate, as do terazosin and doxazosin, but without provoking changes in blood pressure, especially orthostatic hypotension. There appears to be no adverse interaction with any other antihypertensive medication or with low-dose diuretics. To manage such patients with hypertension and prostatism, hydrochlorothiazide 6.25 to 12.5 mg/day and tamsulosin 0.4 mg/day would be an adequate combination. Low-dose diuretics have been shown to be effective in both isolated systolic hypertension as well as fixed diastolic hypertension in the elderly. If other antihypertensives need to be added, then a low dose of a long-acting calcium-entry blocker, a central alpha-agonist (a transdermal clonidine for better compliance), an angiotensin-converting enzyme inhibitor (if renal vascular disease has been ruled out), or an angiotensin II receptor blocker, e.g., losartan or valsartan, should be considered.

Age Factors↗
PubMed1999

Altered IGF-I and IGFBPs in senescent male and female rats.

The effects of senescence on muscle characteristics and the insulin-like growth factor I (IGF-I) pathway were assessed in male and female BN/F344 rats. The mass and total ATPase activity of gastrocnemius and plantaris muscles were reduced with age and to a greater extent in males than in females. The mass and total ATPase activity of soleus muscle were not significantly altered with age. Circulating IGF-I was also significantly reduced with age, 60% in females and 21% in males. Circulating IGF-binding protein 3 (IGFBP-3) was reduced with age. In liver and gastrocnemius muscle, mRNAs for IGF-1, IGFBP-2, and IGFBP-3 were analyzed in young and aged males of two strains, BN/F344 and Sprague-Dawley. In BN/F344 rats, liver mRNAs were unchanged with age. Also in BN/F344 rats, muscle mRNAs for IGFBP-2, and IGFBP-3 displayed nonsignificant trends toward increase with age. In aged Sprague-Dawley males, liver mRNA for IGF-I was increased 15% and muscle mRNA for IGFBP-2 was increased 110%. Thus, different age-related changes in the growth hormone (GH)/IGF pathway occur in males and females between the sexes and strains. These changes may play a role in the muscle atrophy associated with senescence.

Adenosine Triphosphatases↗
PubMed1999

Treatment of nocturia in the elderly.

The aging process, behavioural habits and a multitude of pathological conditions are the main contributors to the development of nocturia in the elderly. Age-related physiological changes can alter the regular pattern of urine excretion and lead to increased nocturnal frequency of voiding. In addition, aging is associated with anatomical and physiological changes of the urinary tract itself that predispose to increased urinary frequency without affecting urine volume. Several urinary and extra-urinary tract conditions may have nocturia as a prominent symptom. These conditions can be grouped as those associated with bladder overactivity, bladder outlet obstruction, bladder hypotonicity and an increased urine volume. A detailed assessment that gathers clues from the medical history, physical examination and laboratory is of utmost importance in identifying the specific causes. Overactive bladder can be idiopathic or associated with different triggers such as UTI, bladder stones, bladder tumours and CNS diseases that disrupt the normal inhibitory signals to the bladder. It may be cured by the successful elimination of the trigger conditions. Therapeutic modalities include behavioural therapies with scheduled voiding, anticholinergic drugs and in women the use of transvaginal electrical stimulation. Benign prostatic hyperplasia is the most common cause of bladder outlet obstruction in men. Different drug classes (e.g. peripheral alpha-adrenoceptor blockers and 5 alpha-reductase inhibitors) are now available for the treatment of mild to moderate symptoms. Surgery is reserved for patients with severe symptoms or with complications, with new and less invasive surgical techniques being preferred. Bladder hypotonicity is usually caused by peripheral neuropathies, spinal cord lesions and the indiscriminate use of drugs with anticholinergic actions. Treatment involves discontinuation of implicated drugs, short term use of cholinergic drugs and urinary catheterisation. Increased urine volumes and nocturia are frequently seen in hyperosmolar and oedematous states. Excessive ingestion of fluids, caffeinated or alcoholic beverages are habits that commonly produce nocturia. Although more definitive studies are awaited, low dose loop diuretics given a few hours prior to bedtime and desmopressin nasal spray or tablets may be useful alternatives for the control of nocturic symptoms in elderly patients with nocturnal polyuria syndrome. Whenever nocturia is present, clinicians should try to identify its causes by means of a thorough history, physical examination and pertinent complimentary tests. Once the specific cause or causes are found, most cases can be satisfactorily managed with behavioural, pharmacological or surgical therapies.

Aged↗
PubMed1998

Physical activity and cardiovascular health in the elderly.

People over the age of 65 constitute a growing proportion of the world population both in western and in developing countries. A unique feature of this group is the high prevalence of cardiovascular diseases, which negatively affect its quality of life as well as its life expectancy. Among the interventions able to reduce the health burden of cardiovascular diseases is physical activity. The benefits of physical activity have been demonstrated both in healthy and chronically ill elderly subjects, while the risks have been found to be modest. Physicians should recommend moderate-intensity physical activity to sedentary older subjects, who are still the majority within the elderly population.

Aging↗
PubMed1998

The effects of endurance exercise training on ambulatory blood pressure in normotensive older adults.

This study investigated the effects of 16-weeks of endurance exercise training (EET) on ambulatory blood pressure in older adults. Twenty-one men and women, 68.5 +/- 4.7 (mean +/- SD) years of age were randomly assigned to an exercise group (EG, n = 11) or to a control group (CG, n = 10). Subjects were normotensive (mean resting BP 132.0 +/- 8.6/80.1 +/- 6.6 mm Hg), free from overt cardiovascular or renal diseases, and were taking no vasoactive or diuretic medications. Maximal oxygen uptake (VO2max), body composition, resting BP, and 24-hr ambulatory systolic (ASBP) and diastolic (ADBP) blood pressures were measured in all subjects before and after the study period. The EG completed 16 weeks (3, 1-hour bouts/wk) of EET, progressing in intensity from 50% to 85% of maximal workload. The CG did not exercise. In the EG, although body composition and resting BP did not change (p > 0.05), VO2max increased by 14% (p = 0.001), mean 24-hr ASBP decreased 7.9 mm Hg (p = 0.0001), and mean 24-hr ADBP decreased 3.6 mm Hg (p = 0.002). In the CG, there were no significant changes in these variables (p > 0.05). These data suggest that EET can improve both aerobic fitness and "real-life" blood pressures in healthy older adults and may help inhibit increases in blood pressure associated with normal aging.

Aged↗