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Biomedical subjects

C Foster

Publications and source records attributed to C Foster.

At least 109 records · Page 6Linked to original sources
PubMed1994

Skeletal muscle fiber type, resistance training, and strength-related performance.

The research goal was to attempt to clarify the consequences of increased strength on performance at submaximal exercise intensities. Eight subjects (4 males, 4 females) completed a 3-d.wk-1, 16-wk resistance training regimen. After training, upper (bench press, BP) and lower (parallel squat, PS) extremity strength were increased by 23% and 37%, respectively. Performance at the same absolute work rates as before training was increased by 30-159% following training depending on intensity and type of exercise. Performance at the same relative work rates (80%, 60%, 40%) remained unchanged by the training for both exercises. Prior to training, PS repetitions at 40% were correlated (r = 0.69, P < 0.05) with the percentage of slow-twitch (ST) fibers in the vastus lateralis muscle. There were similar relationships at 40% (r = 0.73) and at 60% (r = 0.83) for the PS exercise after training. However, the resistance program did not result in greater relative submaximal performance in individuals with a higher percentage of ST fibers. We conclude that strength improvement of up to 40% does not produce a strength-related performance deficit, when training and testing procedures are identical. Yet, these data do not rule out the potential of a strength-related repetition performance deficit. When subjects were equally divided by strength levels, those tested at the highest absolute resistance had significantly lower bench press repetition performance at 60% and 40% of the 1-RM than the subjects tested at the lowest absolute resistance.

Adult↗
PubMed1994

How effective is training for blood pressure measurement?

Monitoring blood pressure is a procedure most medical and nursing staff frequently perform, and forms the basis for many decisions about treatment. This study, however, highlights a disturbing lack of clarity among practitioners about how the procedure should be performed.

Blood Pressure Determination↗
PubMed1993

Chronic liver disease due to hepatitis C.

The low concentration of hepatitis C virus in the blood of infected patients has made it difficult to detect. Infected patients can now be identified by using more sensitive immunoassays and amplification of viral RNA by the polymerase chain reaction. Nevertheless, the virus remains difficult to eliminate. We present the case of a woman with a history of autoimmune haemolytic anaemia, thrombocytopenia, and common variable immunodeficiency who developed chronic hepatitis.

Adult↗
PubMed1993

Unconventional medicine in the United States. Prevalence, costs, and patterns of use.

BACKGROUND: Many people use unconventional therapies for health problems, but the extent of this use and the costs are not known. We conducted a national survey to determine the prevalence, costs, and patterns of use of unconventional therapies, such as acupuncture and chiropractic. METHODS: We limited the therapies studied to 16 commonly used interventions neither taught widely in U.S. medical schools nor generally available in U.S. hospitals. We completed telephone interviews with 1539 adults (response rate, 67 percent) in a national sample of adults 18 years of age or older in 1990. We asked respondents to report any serious or bothersome medical conditions and details of their use of conventional medical services; we then inquired about their use of unconventional therapy. RESULTS: One in three respondents (34 percent) reported using at least one unconventional therapy in the past year, and a third of these saw providers for unconventional therapy. The latter group had made an average of 19 visits to such providers during the preceding year, with an average charge per visit of $27.60. The frequency of use of unconventional therapy varied somewhat among socio-demographic groups, with the highest use reported by nonblack persons from 25 to 49 years of age who had relatively more education and higher incomes. The majority used unconventional therapy for chronic, as opposed to life-threatening, medical conditions. Among those who used unconventional therapy for serious medical conditions, the vast majority (83 percent) also sought treatment for the same condition from a medical doctor; however, 72 percent of the respondents who used unconventional therapy did not inform their medical doctor that they had done so. Extrapolation to the U.S. population suggests that in 1990 Americans made an estimated 425 million visits to providers of unconventional therapy. This number exceeds the number of visits to all U.S. primary care physicians (388 million). Expenditures associated with use of unconventional therapy in 1990 amounted to approximately $13.7 billion, three quarters of which ($10.3 billion) was paid out of pocket. This figure is comparable to the $12.8 billion spent out of pocket annually for all hospitalizations in the United States. CONCLUSIONS: The frequency of use of unconventional therapy in the United States is far higher than previously reported. Medical doctors should ask about their patients' use of unconventional therapy whenever they obtain a medical history.

Acupuncture Therapy↗
PubMed1993

Bronchodilator response to nebulized salbutamol in elderly patients with stable chronic airflow limitation.

The bronchodilator response to 5 mg nebulized salbutamol was studied in 20 elderly patients with stable chronic airflow limitation. Salbutamol produced significantly greater increases in FEV1 and FVC compared with placebo although there was no difference in subjective sensation of breathlessness. Spirometry can be successfully used to assess respiratory function in appropriately selected elderly patients with chronic airflow limitation.

Aerosols↗
PubMed1993

A physiological/psychological indicator of over-reaching during intensive training.

Many indicators of over-reaching and over-training have been proposed, using both physiological and psychological techniques. Field testing of athletes has led us to believe that a decrease in the ratio of blood lactate concentration to ratings of perceived exertion indicates a fatigued and/or over-reached state following intensive training. The purpose of this study, therefore, was to test the hypothesis that a decrease in the ratio of blood lactate concentration to ratings of perceived exertion would indicate an over-reached state. Seven well-trained male cyclists performed two weeks each of: normal (moderate) training, overtraining and recovery. During each time period an incremental exercise test was performed to maximal effort with blood lactate concentration (HLa) and ratings of perceived exertion (RPE) obtained for each workload. All seven subjects became over-reached during the two week period of intensive interval training. The ratio of HLa:RPE (multiplied by 100) decreased with all workloads following both one (mean decrease 29.1 +/- 3.0%) and two (mean decrease 48.7 +/- 2.5%) weeks of overtraining. However, only the decrease at the maximal workload was statistically significant. Examining the individual data revealed that at maximal workload all seven subjects had HLa:RPE ratios of less than 100 when over-reached. The ease and speed at which the HLa:RPE ratio can be determined may make it useful for coaches and athletes in monitoring intensive exercise training and recovery.

Adult↗
PubMed1993

Exercise responses to in-line skating: comparisons to running and cycling.

A comparison of the physiological responses to in-line skating with the more traditional modes of exercise training has not been reported. The purpose of this study was to examine the physiological responses to in-line skating compared with running and cycling. Nine trained volunteers (2 male, 7 female) performed 3-6 submaximal (30-90% VO2max) workloads with each exercise mode. Oxygen uptake, heart rate and blood lactate were measured during each trial. Across the spectrum of oxygen uptakes studied, heart rate was higher with in-line skating than with cycling or running. At a lactate concentration of 4 mM, oxygen uptake was less for in-line skating and cycling than for running. Therefore, while in-line skating may be an effective mode of aerobic exercise, the training adaptations for in-line skating at 4 mM lactate may not be as great as for running, and at a given HR may be less than for running and cycling.

Adult↗
PubMed1993

Fixed time versus fixed distance protocols for the blood lactate profile in athletes.

Laboratory studies of blood lactate accumulation often use a fixed time protocol to define the onset (4 mM) of blood lactate accumulation (OBLA) or other indices of blood lactate concentration. For practical reasons, field studies with athletes often use a fixed distance protocol to accomplish the same goal. Whether these variations of protocol are comparable has not been established. We studied 10 subjects in the laboratory during fixed time (4 minute) and fixed distance (2 km) exercise protocols on a racing bicycle attached to a wind load simulator. The fixed distance studies required 3-6 minutes to complete. We also studied the subjects during fixed distance (2 km) rides in the field. In the laboratory there were no systematic differences in the velocity (34.3 4.6 vs 34.2 +/- 4.6 km.hr-1), VO2 (2.78 +/- 0.60 vs 2.84 +/- 0.62 liters.min-1), or heart rate (159 +/- 16 vs 155 +/- 14 beats.min-1) at OBLA in the fixed time vs fixed distance protocols. The correlation coefficients for velocity (r = 0.97), VO2 (r = 0.97) and heart rate (r = 0.94) further indicate the similarity of results. In the field study there was a significant difference in velocity (29.9 +/- 4.8 vs 34.2 +/- 4.6 km.hr-1) but not heart rate (155 +/- 18 vs 155 +/- 15 beats.min-1) at OBLA versus the fixed distance laboratory study. The correlations for velocity (r = 0.47) and heart rate (r = 0.93) support these data. The results suggest that the practical modification of the lactate profile technique of using fixed distance versus fixed time exercise stages does not systematically influence the outcome, at least for exercise stage durations approximating 4 minutes.

Female↗
PubMed1993

Atrial natriuretic factor potentiating and hemodynamic effects of SCH 42495, a new, neutral metalloendopeptidase inhibitor.

Neutral metalloendopeptidase (NEP) inhibitors delay atrial natriuretic factor (ANF) catabolism and potentiate biological responses to ANF. We describe biochemical and pharmacological profiles of a novel NEP inhibitor, SCH 42354 (N-[2(S)-(mercaptomethyl)-3-(2-methylphenyl)-4-oxopropyl]-L-methionine and its orally active ethylester prodrug, SCH 42495. SCH 42354 selectively inhibited hydrolysis of leu-enkephalin and ANF (IC50 of 8.3 and 10.0 nmol/L, respectively) in vitro. Plasma levels of exogenous ANF were augmented and ANF clearance from plasma was delayed by oral SCH 42495 (3 to 30 mg/kg) in normotensive rats. Plasma ANF levels in volume expanded rats were higher in SCH 42495-treated rats. Diuretic and natriuretic effects of ANF were increased in rats treated with SCH 42495. Oral doses of 1, 3, or 10 mg/kg of SCH 42495 produced significant reductions in blood pressure in DOCA-Na hypertensive rats of 22 +/- 6, 43 +/- 7, and 62 +/- 12 mm Hg, respectively, which were not associated with increases in heart rate. These doses did not alter urine flow, salt excretion, or plasma ANF. SCH 42495 produced significant elevation of urinary excretion of ANF and cGMP. In Dahl-S hypertensive rats, SCH 42495 (1 to 10 mg/kg orally) produced falls in blood pressure of a magnitude similar to that observed in DOCA-Na hypertensive rats. Significant hypotensive activity was observed 18 h after a single 10 mg/kg oral dose in Dahl-S hypertensive rats. In DOCA-Na hypertensive rats, a single dose of SCH 42495 significantly decreased cardiac output and did not lower systemic vascular resistance, a profile similar to that of ANF. The hypotensive response to SCH 42495 was not ascribable to ACE inhibition. Pithed rat preparations revealed no interaction of the drug with autonomic cardiovascular function. The antihypertensive effect of SCH 42495 likely results from potentiation of endogenous ANF via NEP inhibition.

Animals↗
PubMed1993

In vitro HPV-11 infection of human foreskin.

Study of the infectious process of human papillomavirus type 11 (HPV-11) has been facilitated by the discovery that HPV-11-infected neonatal human foreskin epithelium can proliferate as xenografts into condyloma-like growths within athymic nude mice. Here we describe detection of HPV-11 infection of neonatal human foreskin-derived keratinocytes, infected and cultured entirely in vitro, by use of the polymerase chain reaction and primers straddling the splice donor/acceptor site of the most prevalent early gene HPV-11 transcript (E1 increase E4). Expression of the E1 increase E4 HPV-11 mRNA is abrogated by 60 degrees C heat inactivation of the inoculum. HPV-11-infected foreskin explants continue to produce the E1 increase E4 mRNA for up to 5 weeks in culture, and second-passage keratinocytes derived from infected explant outgrowths continue to produce the E1 increase E4 mRNA. The in vitro system described here provides a new way to study HPV-11 infection and may be useful in evaluating early events of infection.

Base Sequence↗
PubMed1993

Effects on ventricular arrhythmias of oral captopril and of oral mononitrate started early in acute myocardial infarction: results of a randomised placebo controlled trial.

OBJECTIVE: To assess the effects of oral vasodilator treatment on ventricular arrhythmias in acute myocardial infarction. SETTING: Coronary care units at the John Radcliffe Hospital, Oxford, and the Royal Infirmary, Edinburgh. PATIENTS: 100 patients with suspected acute myocardial infarction entered the study at a mean of 13 hours from symptom onset. DESIGN OF INTERVENTION: Double blind randomisation to 4 weeks treatment with captopril (12.5 mg three times a day after a 6.25 mg test dose (n = 32)) or isosorbide mononitrate (20 mg three times a day (n = 31)) or placebo control (n = 37). OUTCOME MEASURES: Ventricular arrhythmic events assessed by 48 hours of Holter monitoring starting at the time of randomisation. RESULTS: The number of ventricular extrasystoles/hour for captopril, mononitrate, and placebo was respectively (median and range) 6 (0-162), 4 (0-38), and 10 (0-932) (2p < 0.02 mononitrate v placebo). The number of episodes of multiple extrasystoles/hour was 0.2 (0-22), 0.3 (0-4), and 0.5 (0-19); (2p < 0.02 mononitrate v placebo). Episodes of ventricular tachycardia showed a non-significant decrease in the captopril and mononitrate groups (mean (SEM) 3.2 (0.8), 2.4 (0.7), and 4.7 (1.3) for the 48 hour period). The incidence of idioventricular rhythm was also reduced in both active treatment groups (28%, 19%, and 46% (2p < 0.05 mononitrate v placebo)). CONCLUSIONS: Oral mononitrate (and perhaps also captopril) seems to reduce the incidence of ventricular arrhythmias in the early phase of acute myocardial infarction. The effects on life-threatening arrhythmias, such as ventricular fibrillation, and on death can only be assessed in a much larger trial.

Administration, Oral↗
PubMed1993

Bias and variability in blood pressure measurement with ambulatory recorders.

This study sought to determine whether patient characteristics such as age, sex, blood pressure, and pulse pressure differently affect the accuracy of an oscillometric (SpaceLabs 90207) and a microphonic (TM2420 version 7) blood pressure monitor. Blood pressure recorded by two oscillometric and two microphonic ambulatory monitors was compared with simultaneous readings by two pairs of trained, blinded observers using random-zero sphygmomanometry. One hundred and eighteen subjects (53 men and 65 women, aged 17 to 94 years; systolic pressure, 89 to 211 mm Hg; diastolic, 44 to 116 mm Hg) were studied. There were no significant differences within each observer pair or between the two observer pairs as well as no correlation between interobserver differences and patient characteristics. The differences between the monitor and trained observers' readings were 2.8 +/- 9.9 mm Hg systolic and 3.9 +/- 6.8 mm Hg diastolic for the SpaceLabs and 5.0 +/- 5.2 mm Hg systolic and 3.4 +/- 6.1 mm Hg diastolic for the TM2420. Patient characteristics that predicted measurement error were defined by multiple regression. For oscillometry, systolic measurement error was highly correlated with systolic pressure, pulse pressure, and subject age. The diastolic error was significantly correlated with pulse pressure, diastolic pressure, and subject sex. For the oscillometric monitor, patient characteristics accounted for 36.6% of the variation of the systolic error and 34.7% of the variation of the diastolic error. For the microphonic monitor, only age correlated with diastolic error, and no significant correlations were seen with systolic error. Patient characteristics accounted for only 1.2% of the systolic and 8.9% of the diastolic error.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Overtraining in endurance athletes: a brief review.

Overtraining is an imbalance between training and recovery, exercise and exercise capacity, stress and stress tolerance. Stress is the sum of training and nontraining stress factors. Peripheral (short-term overtraining, STO) or peripheral and central fatigue may result (long-term overtraining, LTO). STO lasting a few days up to 2 wk is termed overreaching. STO is associated with fatigue, reduction, or stagnation of the 4 LT performance capacity (performance at 4 mmol lactate or comparable criterion), reduction of maximum performance capacity, and brief competitive incompetence. Recovery is achieved within days, so the prognosis is favorable. LTO lasting weeks or months causes overtraining syndrome or staleness. The symptomatology associated with overtraining syndrome has changed over the last 50 yr from excitation and restlessness (so-called sympathetic form) to phlegmatic behavior and inhibition (so-called parasympathetic form). Increased volume of training at a high-intensity level is likely the culprit. The parasympathetic form of overtraining syndrome dominates in endurance sports. Accumulation of exercise and nonexercise fatigue, stagnation, or reduction of the 4 LT performance capacity, reduction in maximum performance capacity, mood state disturbances, muscle soreness/stiffness, and long-term competitive incompetence can be expected. Complete recovery requires weeks and months, so the prognosis is unfavorable. Other optional or further confirmation requiring findings include changes in blood chemistry variables, hormone levels, and nocturnal urinary catecholamine excretion. Based on the findings reported, recommendations for training monitoring can be made, but their relevance in the practice must still be clarified.

Exercise↗
PubMed1993

Physiological responses during simulated competition.

Laboratory studies with competitive athletes often use graded exercise protocols to elicit physiologic responses. This pattern of power output is different than ordinarily employed by athletes during competition. To understand the physiologic responses during competition, we studied 24 athletes (speed skaters, cyclists, triathletes) during simulated competition, a 5-km time trial on a racing bicycle attached to a windload simulator, and during cycle ergometer graded exercise testing (N = 8). During the time trial the velocity pattern was similar to real world competitions, and the subjects indicated that the time trial was perceptually similar to competition. Physiologic responses were of significantly greater magnitude vs graded exercise (VO2max: 3.46 +/- 0.73 vs 3.27 +/- 0.79 l.min-1; VEmax: 138 +/- 27 vs 119 +/- 22 l.min-1; HRmax 184 +/- 11 vs 175 +/- 11 beats x min-1; HLa 14.8 +/- 3.7 vs 11.9 +/- 2.1 mM). All physiologic measures increased steadily throughout the time trial (km 0, 1, 2, 3, 4, and 5: VO2 = 1.03, 2.95, 3.42, 3.69, 3.82, and 3.92 l.min-1; HR = 93, 175, 181, 185, 189, and 194 beats.min-1; VE = 31, 99, 120, 129, 145, and 156 l.min-1; HLa = 2.9, 5.6, 7.2, 9.2, 10.6, and 13.5 mM). In six subjects (speed skaters), the peak values observed during time trial for HR (188 +/- 6 vs 191 +/- 5 beats.min-1) and HLa (16.4 +/- 3.1 vs 17.0 +/- 4.2 mM) were not significantly different than observed during real world competition.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Hypertension, diabetes, and obesity in Barbados: findings from a recent population-based survey.

A stratified random sample of 464 persons aged 40 to 79 years, drawn from enumeration registers in the Bridgetown area of Barbados, participated in this survey. The prevalence of hypertension (defined as systolic blood pressure of at least 160 mm Hg, diastolic blood pressure of at least 95 mm Hg, or use of antihypertensive medication) was 47% and 43% for women and men, respectively. Diabetes was present in 17% of all subjects (18% of women and 15% of men). Of the 209 hypertensive subjects, 82% were aware of their blood pressure status. The proportion of previously diagnosed hypertensive subjects on medication was 72% for men and 68% for women. Fifty-three percent of men and 42% of women were overweight (body mass indices [weight in kilograms divided by height in meters squared] between 25 and 30). However, 30% of women and 10% of men were obese (body mass indices over 30), supporting the growing recognition of the marked gender disparity in obesity among persons of African origin in the Caribbean. Body mass index was positively associated with hypertension (OR = 1.33; 95% CI: 1.1-1.6). Obese persons experienced a 2.6 times greater risk of hypertension compared to those with body mass indices below 25. Similar statistically significant associations were observed between diabetes and body mass index: OR comparing body mass index over 30 with body mass index under 25 was 2.5 (95% CI: 1.3-5.1) for all subjects, 1.0 (0.3-4.1) for men only, and 5.2 (1.9-14) for women only. Preventing obesity in this population could reduce the incidence of hypertension and diabetes by approximately 30% and 33% among men and women, respectively.

Adult↗
PubMed1993

Effect of pacing strategy on cycle time trial performance.

Despite interest in competitive strategy by coaches and athletes, there are no systematically collected data regarding the effect of differences in pacing strategy on the outcome of middle distance (2-4 min duration) events. In this study different pacing strategies were evaluated using a 2-km time trial on a bicycle attached to a wind load simulator. Well-trained subjects (N = 9) performed five separate time trials with the pace during the first 50% of the trial experimentally constrained within the usual real world range from very slow (approximately 55% of best time) to very fast (approximately 48% of best time). Serial VO2 was measured to estimate the oxidative contributions to the trial and accumulated O2 deficit and postexercise blood lactate measured to estimate the anaerobic contribution to the trial. The evenly paced trial (first 1 km = 50.9% final time) produced the fastest total time. The starting pace to final time relationship was described by a U shaped second order polynomial curve with the nadir for final time at a starting pace of 51% of best total time. There were no systematic differences in serial VO2, accumulated O2 deficit, or postexercise lactate that could account for the pacing related variations in performance. The data support the concept of relatively even pacing in middle distance events with negative consequences for even small variations in this strategy.

Analysis of Variance↗
PubMed1992

The relationship between age and depressive symptoms in two national surveys.

There is inconsistency in the literature on the relationship between age and depressive symptoms. Although a careful review shows that some of this inconsistency can be reconciled by recognizing the nonlinear relationship (Newmann, 1989), 2 additional issues remain unclear. One is that most previous studies used depression screening scales that contain somatic items that could introduce an age bias. The other is that most previous studies combined samples of men and women even though there is evidence that the sex difference in depressive symptoms varies with age. These 2 issues are addressed in this article, using analyzed data from 2 large national surveys. There is a consistent, but quite modest, nonlinear association between age, somatic, and nonsomatic depressive symptoms in both surveys. There is no significant sex difference in the age curves.

Adult↗