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Biomedical subjects

L A Wolfe

Publications and source records attributed to L A Wolfe.

At least 19 recordsLinked to original sources
PubMed1992

Relationships between cardiac dimensions, anthropometric characteristics and maximal aerobic power (VO2max) in young men.

Echocardiographic dimensions, anthropometric data and maximal oxygen uptake (VO2max) were studied in 26 healthy sedentary male controls (mean age, 22.0 yrs) and 15 male endurance athletes (mean age, 20.3 yrs). Athletes displayed significantly greater mean values for left ventricular internal dimension at end-diastole (LVIDd), end-diastolic volume (LVEDV) and left ventricular mass (LVM). Statistically significant positive correlations were observed within the sedentary control group between left ventricular end-diastolic dimensions (LVIDd, mm and/or LVEDV, cm3) and body height (cm), body weight (kg), chest circumference (cm) and body surface area (m2). Left ventricular mass (LVM, g) correlated significantly with lean body mass (kg). Ectomorphic somatotype rating (Ecto) correlated negatively with LVEDV and LVM. Finally, VO2max (l/min) correlated significantly with LVIDd, LVEDV and LVM. Multiple linear regression analysis indicated that the degree of endomorphy (Endo), LVIDd (mm/m2) and chest circumference accounted for 89% of the variance in VO2max (ml/kg/min) within the athlete group. Endo, Ecto and LVIDd (mm/m2) accounted for 86% of the variance in VO2max (ml/kg/min) in the control group. This study supports the hypothesis that maximal aerobic power can be predicted from cardiac and anthropometric measurements.

Adult↗
PubMed1992

Cardiac responses of young women to conditioning for a 10 kilometer race.

Seven previously sedentary women (mean age, 19 yrs) participated in an 11-week running program (4-5 sessions/week) in preparation for a 10 km race. Training intensity was 80-85% of maximum heart rate reserve. Exercise duration began at 20 minutes/session and was lengthened 5 minutes/session every 2 weeks. A control group consisting of 4 women was also evaluated. Maximal oxygen uptake (VO2max, ml/kg/min) increased 11% in the trained group and decreased 6% in the control group during the study (p less than 0.05). Oxygen uptake, cardiac output (Q), and stroke volume (SV) increased significantly (p less than 0.05) in the trained group during each of 3 levels of steady state cycle ergometer exercise (heart rate targets: 115, 135 and 155 beats/min, respectively). Arteriovenous oxygen difference (a-V02 diff) was not increased significantly after training. Resting left ventricular dimensions and performance evaluated by echocardiography also did not change significantly after training. It was concluded that short-term conditioning in this population results in an increased exercise Q without concomitant increases in left ventricular dimensions or arteriovenous oxygen difference.

Adult↗
PubMed1992

Microscopy of bone cells, bone tissue, and bone healing around implants.

Newer methods of scanning microscopy using both light and electrons are particularly relevant to the study of bone cells, bone matrix organization, matrix mineralization, bone modeling and remodeling, and the adaptation of cells and matrix to implants. Most of such studies are conducted on retrieved implants, at least after the death of the related tissue. Because the retention of the tissue-implant relationship in such preserved tissue is crucial for critical evaluation of the implant, methods based on the study of flat surfaces of embedded tissue blocks are very important. Using electrons, the backscattered electrons in a scanning electron microscope can be employed to evaluate mean atomic number (density) and cathodoluminescence can identify polymers and fluorescent labels. Using light, confocal microscopical techniques permit the examination of layers deep to the block face. Confocal reflected and fluorescence methods allow the study of cell behavior upon both transparent and opaque substrates in the laboratory. Examples of the above are presented and interpretation problems discussed. Current experiments are aimed at enabling the study of bone wound healing and bone adaptation to implanted materials in vivo, through the implantation of optical quality windows and/or newly conceived and designed microscopical objective lenses.

Animals↗
PubMed1991

Microculture screening assay for primary in vitro evaluation of drugs against Pneumocystis carinii.

Pneumocystis carinii inoculated into 96-well filtration plate assemblies was shown to synthesize radiolabeled folates de novo from [para-3H]aminobenzoic acid ([3H]pABA). At the end of each incubation with [3H]pABA, a vacuum manifold was used to remove the medium and wash P. carinii. The membrane at the base of each well was dried and punched out, and the level of 3H retained was determined by direct scintillation counting. High-pressure liquid chromatography analysis of duplicate filters confirmed that direct counting of 3H retained on membranes (after correction for unmetabolized [3H]pABA) was an accurate reflection of total [3H]pABA incorporation by P. carinii. Greater than 95% of the 3H recovered was shown to be present as polyglutamated species. After digestion with rat plasma folic acid gamma-glutamyl hydrolase, para-aminobenzoylglutamate, N10-formyltetrahydrofolate, and tetrahydrofolate were identified as the major 3H-labeled components. para-Aminobenzoylglutamate was presumed to have arisen from folylpolyglutamates synthesized by P. carinii and was therefore included in the calculation of total [3H]pABA incorporation. P. carinii incorporation of [3H]pABA under optimal conditions was used as a selective measure of in vitro viability against which the inhibitory effects of some antipneumocystis agents (pentamidine, sulfamethoxazole, 566C80, and piritrexim) were quantitated. The concentrations of pentamidine, sulfamethoxazole, 566C80, and piritrexim required for 50% inhibition in this assay were 7.3, 0.1, 1.4, and approximately 100 microM, respectively. The results suggest that this 96-well [3H]pABA incorporation assay has considerable potential for objective in vitro drug screening against P. carinii.

4-Aminobenzoic Acid↗
PubMed1991

The 'athletic heart syndrome'. A critical review.

Cardiological findings in athletes are often similar to those observed in clinical cases. Electrocardiographic and cardiac imaging abnormalities as well as physical findings may be the same in both of these groups. Bradycardia and rhythm disturbances are the most common abnormalities in athletes. Most athletes with abnormal electrocardiograms are asymptomatic and numerous investigators have failed to detect heart disease in association with such electrocardiograms. In contrast to cardiac dysfunction observed in clinical cases, enhanced or normal ventricular systolic and diastolic function have been reported in athletes. In endurance athletes, this is associated with very high values for maximal aerobic power (VO2max). Absolute and body size-normalised cardiac dimensions in most athletes do not approach values from chronic disease states, and may not exceed echocardiographic normal limits. In addition, pathological and physiological enlargement appear to be biochemically and functionally different. Myosin ATPase enzyme expression and calcium metabolism are different in rats with pathologically or physiologically induced enlargement. The reported biochemical differences underlie systolic and diastolic dysfunction in pathological enlargement. Conversely, trained rodents and humans have demonstrated enhanced systolic and diastolic function. It is important to note that cardiac enlargement observed in athletes is the result of normal adaptation to physical conditioning and/or hereditary influences. Conversely, pathological changes result from disease processes which can lead in turn to reduced function, morbidity and mortality. Since the mid 1970s echocardiography has been used to compare cardiac dimensions in male endurance- and resistance-trained athletes. A sport-specific profile of eccentric and concentric enlargement has been documented in endurance and resistance athletes, respectively. Subsequent studies of athletes have examined factors such as age, sex and degree of competitive success to determine their contribution to these sport-specific cardiac profiles. Unique athletic subgroups have also been analysed and have included ballet dancers, rowers, basketball players and triathletes. However, there is a paucity of data on cardiac dimensions in female athletes. Finally, physical conditioning studies have also examined echocardiographic dimensions before and after endurance and resistance training. Significant enlargement of internal dimensions, wall thickness or left ventricular mass have been reported but such increases are relatively small and by no means universal. Several conflicting explanations for enlarged cardiac dimensions appear in the literature. Chronic volume and pressure haemodynamic overloading during physical conditioning has been proposed to explain eccentric and concentric cardiac enlargement in endurance- and resistance-trained athletes respectively. However, twin studies suggest that hereditary factors may be important determinants of cardiac dimensions and/or the degree of cardiac adaptability to physical conditioning.(ABSTRACT TRUNCATED AT 400 WORDS)

Body Mass Index↗
PubMed1990

Fluorescence in the tandem scanning microscope.

Our studies have shown that the fluorescence mode can be used to good effect in both tandem scanning microscopes (TSM: direct view confocal microscopes) as well as confocal scanning laser microscopes (CSLM). Applications are presented which show that the two great advantages of TSM are real-time viewing and real colour, which allow faster use and interpretation. CSLM are complementary, not competitive, being currently more sophisticated for low-level fluorescence work. This is equally possible with available TSM, but requires further development using CCD cameras and image-processing systems.

Animals↗
PubMed1989

An in vitro analogue of immune dysfunction with altered immunoglobulin production in the aged.

The consequences of aging of the immune system include impaired T-lymphocyte responsiveness and aberrant immunoglobulin production. Although T cells from elderly individuals have a well-described defect in lymphoblastic transformation in response to some polyclonal mitogens, immunoglobulin abnormalities have lacked a clear in vitro model. Peripheral blood mononuclear cells from 13 young and 13 old healthy donors were cultured with phytohemagglutinin (PHA) or pokeweed mitogen (PWM). Old-donor-cell phytohemagglutinin (PHA), but not PWM, cultures had significantly lower lymphoblastic transformation compared with young donor cultures. IgG, IgA, and IgM production tended to be lower in old- versus young-donor PWM cell cultures. By contrast, despite lower lymphoblastic transformation in old-donor PHA cell cultures, immunoglobulin production was higher for old- versus young-donor cell cultures. No significant age differences were present in initial lymphocyte counts, percent B cells, T cells or monocytes, or helper/suppressor ratios to explain this enhancement in immunoglobulin production. PHA-stimulated mononuclear cell cultures in the aged demonstrate not only a defect in proliferation but also increased immunoglobulin production. This in vitro system may be useful to characterize further the pathogenesis of altered immunoglobulin production in the elderly.

Adult↗
PubMed1989

Prescription of aerobic exercise during pregnancy.

Available evidence supports the existence of both risks and benefits of aerobic conditioning during human pregnancy. During intensive exertion, maternal skeletal muscle and the fetus may compete for blood flow, oxygen delivery and essential fuel substrates. Hence, the most important hypothetical risks include acute fetal hypoxia, hyperthermia and malnutrition. If exercise is repeated on a chronic basis, teratogenic effects, fetal growth retardation or altered fetal development may result if maternal/fetal adaptive reserve is exceeded. A dose-response relationship for such effects has been demonstrated in laboratory animals, but specific findings may have limited applicability to voluntary exercise in pregnant women. Although further investigation is needed, the majority of published studies suggest that fitness-type conditioning does not jeopardise fetal well-being in healthy well-nourished women. Benefits of such exercise appear to include increases in maximal aerobic power (VO2max, L/min) and enhanced cardiopulmonary reserve. It has also been proposed that exercise prevents accumulation of excess body fat, promotes psychological well-being, helps to prevent gestational diabetes and low back pain and may facilitate labour. However, these benefits remain to be confirmed by objective scientific study. Due primarily to a lack of scientific data, existing medical guidelines for exercise during pregnancy are conservative and follow a common sense approach. Good agreement exists on the need for preparticipation medical screening and continuing surveillance to verify the existence of maternal/fetal adaptive reserve. Women are advised to select safe, non-ballistic exercise modalities and to avoid thermal or hyperbaric environmental stress during exercise. Exercise in the supine position is also prudent to avoid, particularly in late gestation. The usefulness of heart rate in prescribing and monitoring exercise intensity has been questioned, with use of conventional perception of exertion scales being the most logical alternative. Prediction of maximal aerobic power (VO2max) from submaximal work rate/heart rate relationships is also problematic during pregnancy. Other areas of debate include the advisability of initiating a new exercise programme during pregnancy, methods for prevention of fetal hyperthermia, the safety of weight-training/isometric exercise and optimal methods for training of pre/postnatal fitness instructors.

Exercise Therapy↗
PubMed1989

Bone response to a matched modulus endosseous implant material.

The aim of this study was to assess bone response to a novel matched modulus material using more rigid titanium as a control. Implants subjected to different loading conditions were retrieved from rabbit tibiae after various time intervals, and new bone growth was assessed by histomorphometric methods. Block face microscopy was employed for histologic purposes. From a statistical analysis of the histomorphometric results, it could be concluded that titanium implants encouraged the greatest overall amount of bone formation around them when they were unloaded, when they were loaded immediately, and after a healing period.

Animals↗
PubMed1988

Acute effects of exercise intensity on appetite in young men.

This study investigated the acute effects of two exercise intensities on three measures of appetite. Fifteen, 12-h-fasted, college-age males completed three experimental sessions in counterbalanced orders: no-exercise control; cycle exercise performed at 35% VO2max; and cycle exercise performed at 68% VO2max. Both exercise conditions involved a total energy expenditure of 4.1 kcal.kg-1 body weight. Dependent measures were intermittent hunger and sucrose palatability ratings, and food intake at a test meal given approximately 1 h post-exercise. Hunger was briefly suppressed in the high-intensity exercise condition compared to low-intensity exercise and control, while intake of liquid-source kilocalories and carbohydrates was higher after the exercise sessions. Total caloric intake remained stable. Sucrose palatability did not vary across sessions. Intensity is inferred to be an important variable mediating exercise effects on appetite. Relations between appetite measures are discussed, and validity of sucrose palatability ratings and common methods of measuring food intake questioned. Exercise, while not decreasing food intake, does not appear to increase it, and the benefits of exercise for body fat reduction are not immediately offset by compensatory caloric intake.

Adult↗
PubMed1988

"Flipped" patterns of lactate dehydrogenase isoenzymes in serum of elite college basketball players.

We kinetically measured total lactate dehydrogenase (LD, EC 1.1.1.27), total creatine kinase (CK, EC 2.7.3.2), and aspartate aminotransferase (AST, EC 2.6.1.1.) in 16 elite college basketball players, before the competition season and not in close temporal relation to near-maximal exercise, and in 17 healthy non-athlete controls. LD isoenzymes were determined by both electrophoretic and immunoprecipitation methods. CK-MB isoenzyme was measured electrophoretically. We found significantly higher mean LD-1 values and LD-1/LD-2 ratios in the players than the controls: 31.6 (SD 3.7)% vs 25.8 (SD 3.2)% (P less than 0.005) and 1.1 (SD 0.13) vs 0.87 (SD 0.16) (P less than 0.001), respectively. A "flipped" LD pattern (LD-1 greater than LD-2) was found in half the players and in six of the eight black athletes, but in only two of the control group and in none of the black controls. Mean CK activity in serum exceeded normal values in the serum of the athletes and was higher in comparison with the control group [274 (SD 156) vs 103 (SD 82) U/L]. Mean CK was significantly higher in the eight athletes with the flipped LD pattern than in those with LD-1 less than LD-2 [322 (SD 163) vs 180 (SD 98) U/L; P = 0.05], and also in comparison with CK in the two controls with flipped LD pattern. We saw no significant difference in mean CK between the nine players with normal immunochemical LD-1/LD ratios and the seven players with above-normal ratios. CK-MB was not detected in either athletes or controls. None of the players had any clinical or electrocardiographic evidence for myocardial ischemia or infarction. Evidently the flipped LD pattern usually found in patients with acute myocardial infarction and reported in some athletes after extreme exercise such as ultra-marathon running may also be found in athletes who are in their "basal fitness shape" but who are not involved in competitive physical activity.

Adult↗
PubMed1988

Cardiovascular responses to acute exercise in patients with cerebrovascular accidents.

Blood pressure (BP) and heart rate (HR) responses to isometric hand grip, exercise with the cybex arm ergometer, and cybex fitron cycle ergometer were recorded for 19 stroke subjects and 19 control subjects matched by age and gender. Mean age in both groups was 66 years. There was no significant difference in the resting HR (controls: 69 +/- 10, patients: 70 +/- 11 beats per minute) and BP measurements (systolic--controls: 140 +/- 17, patients: 135 +/- 21; diastolic--controls 80 +/- 8, patients: 75 +/- 11mmHg). There was also no significant difference in either the mean HR (controls: 79 +/- 10, patients: 81 +/- 12 beats per minute) or BP (systolic--controls: 174 +/- 23, patients: 165 +/- 27; diastolic--controls: 98 +/- 15, patients: 92 +/- 14) response to exercise. With the arm ergometer test, the control group attained a significantly higher maximum systolic (190 +/- 23 mmHg) and diastolic blood pressure (102 +/- 15mmHg) than the stroke group (systolic 165 +/- 23; diastolic 91 +/- 10mmHg). During the leg ergometer exercise test, results were similar in both groups except that work completed was significantly higher for the control group (3592 +/- 1162kg) than for patients (2512 +/- 1348kg). None of the patients reported symptoms of dizziness, fainting, or chest pain. Prescribed exercise in stroke patients under supervision and within patient tolerance was found to be safe.

Activities of Daily Living↗
PubMed1986

Physical conditioning effects on cardiac dimensions: a review of echocardiographic studies.

Echocardiographic studies related to chronic exercise effects on cardiac dimensions were reviewed. Sources of error in M-mode echocardiography include its resolving power, changes in transmission velocity in a nonhomogeneous medium, subjective analysis of records, and assumptions to predict ventricular volume and mass from one-dimensional data. Existing studies document larger values for left ventricular internal diastolic dimension (LVIDd) in endurance athletes, and for septal and posterior wall thicknesses (ST, PWT) in endurance, strength-type and anaerobic-type athletes compared to nonathletes. Values for the athletes were lower than in cardiac disease states. Short-term conditioning studies generally reported unimpressive changes in ventricular dimensions. Existing literature also does not clearly support a relationship between training intensity and the degree of cardiac enlargement, or changes in the heart's trainability with age. Hereditary and/or familial factors appear to influence heart size to some degree and a correlation with anthropometric variables may exist. Further study concerning hereditary and long-term conditioning effects is recommended.

Adolescent↗
PubMed1985

Chronic exercise and left ventricular structure and function in healthy human subjects.

Twelve healthy well-trained participants in a supervised exercise program (mean age, 41.3 yr) were compared with 12 sedentary control subjects (mean age, 38.9 yr) with physical characteristics similar to the exercised group (EG) before training. Resting echocardiograms revealed significantly lower heart rates (HR) in the EG compared with control group (CG) but no evidence for cardiac structural differences between groups. Radionuclide angiograms performed at rest and during two levels of supine cycling (HR targets: 120 and 140 beats X min-1) resulted in increases in background-corrected end-diastolic counts [EDC(bc)] and confirmed use of the Frank-Starling mechanism in the majority of subjects. Mean values (+/- SD) for ejection fraction (EF) and normalized peak systolic ejection rate (PSER) (P greater than 0.05 between groups) were the following. (Formula: see text) The results suggested that fitness training does not induce significant cardiac enlargement as apparent from measurements at rest or important changes in contractile state during exercise. Increases in exercise stroke volume with such training may be the result of an increased end-diastolic volume.

Adult↗
PubMed1985

Absence of left ventricular hypertrophy in elite college basketball players.

Left ventricular dimensions of 11 successful male college basketball players engaged in pre-season conditioning (mean age, 20.3 years) and 13 tall healthy male controls (mean age, 21.6 years) were studied by echocardiography. Left ventricular internal dimension (LVIDd, mm), posterior wall thickness (PWT, mm), septal thickness (ST, mm), and calculated left ventricular mass (LV mass, g) in the athletes were within or only slightly in excess of echocardiographic normal limits and mean values were not significantly different from the control group. LVIDd (mm/m2 body surface area) was significantly lower in the athletes. However, five guard-type players displayed significantly greater mean values for PWT and LV mass compared to six taller forwards/centers with linear body builds. It was concluded that left ventricular hypertrophy is not a common characteristic of college basketball players. It was hypothesized that cardiac dimensions of young men may vary independently of gross body size in relation to somatotype or other anthropometric variables.

Adult↗
PubMed1979

Effects of endurance training on left ventricular dimensions in healthy men.

Echocardiography was employed to measure the serial effects of jogging on resting left ventricular dimensions and function. Twelve men were exercised (mean age 36.8 yr) and 10 served as controls (mean age 34.8 yr). Increases of 14 and 18% were observed for predicted aerobic capacity in the training group (TG) after 3 and 6 mo of training, respectively; the control group (CG) displayed a small detraining effect. Echocardiographic findings included a significant (P less than 0.05) reduction in resting heart rate and a moderate increase in stroke volume (SV) in the TG compared to the CG. The increased SV appeared to be due to increased end-diastolic dimensions (LVIDd, LVEDV), secondary to greater ventricular filling rather than a more vigorous ventricular contraction. Posterior wall thickness, septal thickness, and calculated left ventricular muscle mass were not significantly increased in the TG compared to CG after either 3 or 6 mo training. It was concluded that left ventricular structure and resting contractile status are not altered by 6 mo of jogging training in healthy, previously sedentary men.

Heart↗
PubMed1978

Relationship between maximal oxygen uptake and left ventricular function in exercise.

Left ventricular systolic time intervals (STI's), cardiac output, and arterial blood pressures were measured during bicycle ergometer work in three groups of 10 young men (aged 20-33 yr) who represented average (VO2max = 42-45 ml.kg-1.min-1), moderate (VO2max = 50-56 ml.kg-1.min-1), and high (VO2max = 59-72 ml.kg-1.min-1) levels of cardiovascular fitness. The subjects were studied using noninvasive procedures at steady-state heart rate of approximately 110, 130, and 150 beats.min-1. At all exercise levels, the fitter subjects displayed slightly shorter values for the preejection period (PEP) compared with less fit groups. Significantly (P less than 0.05) larger stroke volumes, longer left ventricular ejection times (LVET), faster mean systolic ejection rates and lower PEP/LVET ratios were found in the group with the highest aerobic capacity. Although these observations appear to indicate a superior mean level of left ventricular performance in groups who represent high levels of cardiovascular fitness, it was concluded that the use of STI values by themselves to describe the cardiovascular fitness of an individual would not be warranted.

Adult↗