Comparison of gait of young men and elderly men

The purpose of this study was to describe and compare the free-speed gait characteristics of healthy young men with those of healthy elderly men. Data collection consisted of high-speed cinematography resulting in synchronized front and side views of 24 healthy male volunteers, 12 between 20 and 32 years of age and 12 between 60 and 74 years of age. Young men were recruited to match the elderly men on the basis of right-leg length. Each subject participated in three filmed trials of free-speed ambulation down a 14-m walkway. The processed film was analyzed for eight gait characteristics. Differences in characteristics between the two groups were examined using a correlated t test (p less than .01). No significant differences were observed between the groups for step and stride length, velocity, ankle range of motion, vertical and horizontal excursions of the center of gravity, and pelvic obliquity; however, the younger men demonstrated a significantly larger stride width than the elderly men (p less than .01). The results suggest that the two populations of healthy adult men have similar gait characteristics.     

Thigh composition in young and elderly men determined by computed tomography

Summary. Computed tomography (CT) was used to quantify components of the thigh in young (n= 13) and elderly (n= 11) men. Cross-sectional areas (CSA) of the total limb, total muscle plus bone, quadriceps compartment, hamstring compartment and bone were measured at each of five scan sites along the length of the thigh. Non-muscle tissue (NMT) areas within the muscle compartments were measured using changes in density based on Hounsfield units. Skin plus subcutaneous fat areas and quadriceps and hamstring lean muscle areas were calculated by subtraction. Geometric formulae were used to calculate related volumes for each thigh component. Volumes were also predicted from regression equations employing thigh length and component CSA from single mid-limb CT scans. The results showed that while total thigh CSA was not different in elderly men, they had significantly smaller total muscle plus bone (13-0%), and quadriceps (26.4%), and hamstring (17.9%) muscle areas. The elderly men also had significantly greater CSA for skin plus subcutaneous fat (37-6%), and for NMT in the quadriceps (59.4%) and hamstring (127.3%) muscle compartments. These results suggest that comparisons of relative leg muscle strength between young and elderly men may be misleading due to the decrease in actual muscle tissue associated with ageing. Appropriate quantification of muscle size and CSA must be carried out before such comparisons can be meaningful.     

Prednisolone disposition in obese men

Obesity is accompanied by altered secretion and disposition of sex and glucocorticoid hormones, including cortisol, and also confounds parameter normalization and drug dosage selection relative to body weight. Prednisolone disposition was assessed in eight obese and four normal male subjects after a dose of 33 mg iv. Steroid concentrations were determined by HPLC. Kinetics were related to ideal body weight (IBW) and total body weight (TBW). Uncorrected steady-state volume of distribution (Vss) of total prednisolone was 20% greater in obese subjects (36.7 and 44.1 l). This effect could be described by the relationship: Vss = 0.54 IBW + 0.09(TBW-IBW), with a distribution coefficient of 0.09 reflecting limited prednisolone uptake by fat. Protein binding parameters and albumin and transcortin concentrations were similar between groups. Uncorrected total and free prednisolone clearances (Cl) were increased in obesity (11.1 and 8.3 l/hr total; 65.4 and 46.5 l/hr free). Free prednisolone Cl correlated strongly (r = 0.80) with degree of obesity expressed as TBW/IBW. In the obese, endogenous cortisol concentrations were initially higher before exogenous steroid dosing, were suppressed at an identical rate, and returned to baseline more slowly than in normal subjects. The apparent hypersensitivity of the adrenal gland offsets the increased Cl of free prednisolone in obesity, indicating that weight-proportional dosage adjustments of this steroid in obesity should reflect TBW.     

Detection and decision factors in pain perception in young and elderly men.

The effect of age on ability to discriminate between levels of electrical stimulation of tooth pulp and willingness to report shocks as painful was evaluated using the Sensory Decision Theory. While threshold did not increase with age for tooth pulp stimulation as is often observed for thermal pain thresholds, a significant age deficit in ability to discriminate between suprathreshold shocks was observed. Significant changes with age in willingness to report the electrical shocks as painful were also observed. These results indicate that changes with age in pain perception are complex, involving not only possible discrimination deficits but also changes in bias for and against labeling noxious events as painful. These findings stress the need for within individual comparisons of laboratory techniques for evoking acute pain experiences where variables such as age are under consideration.     

Dehydroepiandrosterone sulfate: kinetics of metabolism in normal young men and women

The constant infusion technique was used to study the kinetics of dehydroepiandrosterone sulfate (DHEAS) metabolism in normal young men and women. The metabolic clearance rates (MCR) (means +/- SEM) for normal young men and women were 15.2 +/- 1.7 1/24 h (8.2 +/- 0.7 1/m2/24 h) and 11.8 +/- 0.8 1/24 h (7.3 +/- 0.4 1/m2/24 h) respectively. Coupled with the plasma levels of 5.07 +/- 1.95 and 4.02 +/- 0.57 mumole/L the resulting blood production rates were 76.7 +/- 25.7 and 48.0 +/- 9.4 mumole/24 h for men and women respectively. The conversion ratios for the conversion of DHEAS to dehydroepiandrosterone (DHEA) were 0.006 for men and 0.004 for women. Because of the high metabolic clearance rates for DHEA relative to those for DHEAS and the high production rates of DHEAS most of the DHEA produced per day can arise from DHEAS.     

Pharmacokinetics of meropenem and its metabolite in young and elderly healthy men.

The pharmacokinetics of meropenem and its ring-opened metabolite (ICI 213,689) were investigated with eight young (20- to 34-year-old) and eight elderly (67- to 80-year-old) healthy male volunteers given single 30-min intravenous infusions of 500 mg of meropenem. All subjects had normal age-correlated glomerular function. The mean terminal half-life of meropenem was 1.27 h in the elderly subjects versus 0.81 h in the younger subjects (P less than 0.001). This and similar increases in mean residence time and area under the concentration-time curve were explained by a reduction in total [139 versus 203 ml/(min.1.73 m2); P less than 0.001], renal, and nonrenal clearances in subjects at advanced ages. The apparent volume of distribution and urinary recovery over 8 h were not significantly altered. With the metabolite, prolonged serum half-life and mean residence time, enlarged area under the concentration-time curve, and lower renal clearance but no significant changes in peak plasma concentration or urinary recovery were found in the elderly. The reduction in the renal excretion rate of meropenem and its metabolite corresponds to the age-associated physiological decline in renal function. The capacity to metabolize meropenem may also be slightly impaired in people at advanced ages. Dose reduction of meropenem should be considered for elderly patients.     

Nadolol antihypertensive effect and disposition in young and elderly adults with mild to moderate essential hypertension

Nadolol was effective and well tolerated as once-daily monotherapy for mild to moderate essential supine diastolic hypertension (SDBP) in 10 young (mean age, 39 years) and 12 elderly (mean age, 68 years) patients in a single-blind, placebo-baseline, escalating-dose study. Doses required to reduce SDBP to 90 mm Hg were not different in young (1.08 +/- 0.21 mg/kg/day) and elderly (0.82 +/- 0.14 mg/kg/day) patients (mean +/- SE). Trough plasma nadolol concentrations at steady state were similar and were linearly related to dose in both groups. More unchanged nadolol was recovered in 24-hour urine samples from young subjects (15.6% +/- 1.9%) than from elderly ones (10.7% +/- 1.1%) (p = 0.028). With increasing nadolol doses, plasma norepinephrine concentration increased and isoproterenol sensitivity decreased in both young and elderly subjects, and creatinine clearance and plasma active renin levels were unchanged; plasma inactive renin levels increased in the young, and aldosterone concentration declined in the elderly with the lowest nadolol dose.     

Arm and leg composition determined by computed tomography in young and elderly men

Summary. Five computed tomography (CT) scans were taken at measured intervals of the legs and arms of young (n=7) and elderly (n=13) men. Cross-sectional areas (CSA) of the total limb, muscle plus bone and bone were measured in each scan, and skin plus subcutaneous tissue areas were calculated by subtraction. In addition, in the arm scans the CSA of the extensor and flexor compartments were measured, and in the leg the CSA of the plantar flexor compartment. A value for lean muscle within these compartments was calculated by excluding non-muscle tissue using density measurements based on Hounsfield units. Related volumes for the various components were also calculated using geometric formulae. The results showed that elderly limbs were of a similar overall size as the young, but elderly muscles were smaller (28–36%) with greater amounts of non-muscle tissue located within a muscle, particularly in the plantar flexors (81% more than in the young). Elderly arms had a greater amount of skin plus subcutaneous tissue than the young, but there was no difference in the legs. Muscle volumes were similar to in vitro results reported from cadaver studies and can be predicted from single mid-limb CT scans using regression equations. These results illustrate that, due to the substantially reduced amount of ‘pure’ muscle tissue in the elderly, comparisons of relative strength with other populations may be misleading unless appropriate measurements of muscle size are considered. Methods to estimate in vivo physiological CSA, which is considered the best means of normalizing strength, have been demonstrated in this study.     

Imipramine and desipramine disposition in the elderly

Forty-six healthy male and female volunteers aged 21 to 88 received single 12.5-mg i.v. doses of imipramine, and 35 of these people received single 50-mg p.o. imipramine doses on a different occasion. Thirty-five similar volunteers received single 50-mg p.o. desipramine doses. Among these subjects 25 participated in studies of both imipramine and desipramine. Kinetic variables for the respective drugs were determined from multiple plasma drug concentrations from samples obtained during 96 hr after the dosage. Imipramine half-life was markedly prolonged in elderly vs. young males (28.6 vs. 16.5 hr; P less than .001) and females (30.2 vs. 17.8 hr; P less than .01) due to decreased clearance (males: 567 vs. 945 ml/min, P less than .01; females: 599 vs. 975 ml/min, P less than .005) with no change in volume of distribution. After p.o. imipramine doses time to peak imipramine concentration was shorter in elderly females (2.1 vs. 4.8 hr; P less than .005) but no different in males. Peak concentration achieved was greater in the elderly of both sexes (males: 40.2 vs. 19.5 ng/ml, P less than .005; females: 44.7 vs. 10.4 ng/ml, P less than .01). Comparison of p.o. and i.v. imipramine doses indicated no difference in absolute bioavailability between the elderly and young of either sex. In contrast, after p.o. desipramine more limited age-related changes were noted. Desipramine half-life was slightly prolonged in elderly males (30.8 vs. 21.2 hr; P less than .05) apparently related to a nonsignificant decrease in p.o. clearance.(ABSTRACT TRUNCATED AT 250 WORDS)     

Joint torques and dynamic joint stiffness in elderly and young men during stepping down

OBJECTIVE: To compare the joint torque pattern and dynamic joint stiffness at the knee and ankle in elderly and young men during stepping down. BACKGROUND: Adequate joint stiffness is critical during the single support phase to control forward and downward body momentum. DESIGN: Six active elderly men (mean 67.7) and six young men (mean 23.6) of similar body mass and height, were filmed stepping down from one force platform to another. Repeated trials were undertaken at three different step heights (200, 250, and 300 mm). METHOD: Joint torques were determined for the ankle and knee of the support limb throughout the single support phase. The gradient of the joint torque-angle graph was calculated to define dynamic joint stiffness of the ankle and knee in two phases; (I) from initiation of movement until heel-off of the supporting limb, and (II) from heel-off of the supporting limb to contra-limb touch down. RESULTS: Maximum ankle torque values were lower in the elderly and occurred at a larger dorsiflexion angle (P<0.05). Knee torque patterns were similar in both groups. Phase I ankle stiffness was significantly less in the elderly (4.0-5.2 Nm/ degrees ) at all step heights compared to the young (7.6 - 8.7 Nm/ degrees ). In both groups ankle stiffness in Phase II increased with step height, while knee joint stiffness decreased. CONCLUSIONS: The different torque pattern and lower dynamic ankle stiffness in the elderly, particularly for Phase I, suggested an altered control strategy. These findings highlight the importance of dynamic ankle joint stiffness in stepping down. RELEVANCE: Understanding how the elderly step down may be important in developing strategies to prevent falls.     

Relative contributions of testosterone and estrogen in regulating bone resorption and formation in normal elderly men

Young adult males who cannot produce or respond to estrogen (E) are osteopenic, suggesting that E may regulate bone turnover in men, as well as in women. Both bioavailable E and testosterone (T) decrease substantially in aging men, but it is unclear which deficiency is the more important factor contributing to the increased bone resorption and impaired bone formation that leads to their bone loss. Thus, we addressed this issue directly by eliminating endogenous T and E production in 59 elderly men (mean age 68 years), studying them first under conditions of physiologic T and E replacement and then assessing the impact on bone turnover of withdrawing both T and E, withdrawing only T, or only E, or continuing both. Bone resorption markers increased significantly in the absence of both hormones and were unchanged in men receiving both hormones. By two-factor ANOVA, E played the major role in preventing the increase in the bone resorption markers, whereas T had no significant effect. By contrast, serum osteocalcin, a bone formation marker, decreased in the absence of both hormones, and both E and T maintained osteocalcin levels. We conclude that in aging men, E is the dominant sex steroid regulating bone resorption, whereas both E and T are important in maintaining bone formation.     

Impotence in elderly men

Impotence in not a concomitant of aging. A diligent search must be undertaken to determine the cause, which may be endocrine, pharmacologic, vascular, neurologic, psychological, or miscellaneous (eg, chronic illness). Many therapies are available for elderly impotent men. Some are based on pharmacology (eg, testosterone supplementation, thyroid replacement, self-injection), some on surgery (eg, vascular reconstruction), and some on a prosthesis (semirigid, inflatable, or mechanical). In choosing the type of treatment, the physician must consider the patient's underlying medical condition, activities of daily living, social life, and partner's expectations in addition to the cause of the impotence.     

Paraphimosis in elderly men

Paraphimosis occurs when the foreskin of the penis is retracted over the glans and cannot be replaced in its normal position. The tight ring of preputial skin constricts the distal penis causing vascular occlusion, much like a tourniquet. The condition is painful and, if not dealt with quickly, can lead to necrosis of the glans. Simple reduction of the prepuce can be achieved by compressing the edematous fluid out of the glans and repositioning the foreskin. Irreducible paraphimosis is treated by dorsal slit procedure and subsequent circumcision. We present two cases illustrating the treatment techniques and possible complications of paraphimosis in men.     

Impotence in elderly men

Although some sexual changes are an inevitable consequence of aging, impotence is not one of them. In most cases, impotence in elderly men has the same causes as impotence in younger men and is treatable. Dr Rousseau discusses the six most common categories of impotence, the approach to evaluation, and treatment options for each type, with the elderly patient in mind.     

The performance of learning-disabled and normal young men on the test of visual-perceptual skills

The present study explored the discriminative validity of the motor-free Test of Visual-Perceptual Skills (TVPS) as an assessment for adults. The subjects were 26 learning-disabled and 26 normal young men. Overall, the subjects with learning disabilities made significantly more errors and took significantly more time on the total TVPS than did the normal subjects. The group with learning disabilities demonstrated significantly lower accuracy scores on four of the seven subtests and longer time scores on five subtests. Discriminant analysis revealed that the time score for Visual Sequential Memory and the accuracy score for Visual Closure were the two subtest scores that best discriminated between groups and, together, were able to correctly classify 84.6% of the subjects. The TVPS total accuracy score for the subjects with learning disabilities significantly correlated with their overall performance IQ but not with their verbal IQ. Their TVPS total accuracy scores also correlated with scores on Block Design, but not with scores on the Object Assembly or Picture Completion subtests of the WAIS-R. The results seem to indicate that the TVPS is valid as an assessment of visual-perceptual functions for young adult subjects. Recommendations for further study were made.     

Palmitate and glycerol kinetics during brief starvation in normal weight young adult and elderly subjects.

Data obtained in vitro suggest that the ability to mobilize fat decreases with age. We determined lipolytic rates in vivo in normal weight young adult (22-33 yr) and elderly (65-77 yr) subjects using a simultaneous infusion of [1,2-13C2]palmitate and [2H5]glycerol. The subjects were studied after a 12-h fast and again after 60-82 h of fasting. When lipolysis was expressed per unit of adipose tissue the values for the young adults were more than double those for the elderly (P less than 0.05). However, the amount of body fat in the elderly was twice that of the young adults, so that lipolysis per unit of body weight was similar in both groups. These results demonstrate that lipolysis per unit of adipose tissue is lower in elderly subjects. This may be due to their increase in body fat, however, since the total amount of potential energy mobilized from adipose tissue was similar to that of the young adults.