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Biomedical subjects

C B Scott

Publications and source records attributed to C B Scott.

At least 73 records · Page 4Linked to original sources
PubMed1991

Women walking for health and fitness. How much is enough?

OBJECTIVE: We studied whether the quantity and quality of walking necessary to decrease the risk of cardiovascular disease among women differed substantially from that required to improve cardiorespiratory fitness. DESIGN: A randomized, controlled, dose-response clinical trial with a follow-up of 24 weeks. SETTING: A private, nonprofit biomedical research facility. PARTICIPANTS: One hundred two sedentary premenopausal women, 20 to 40 years of age, were randomized to one of four treatment groups; 59 completed the study (16 aerobic walkers [8.0-km/h group], 12 brisk walkers [6.4-km/h group], 18 strollers [4.8-km/h group], and 13 sedentary controls). Eighty-one percent were white, 17% black, and 2% Hispanic. INTERVENTION: Intervention groups walked 4.8 km per day, 5 days per week at 8.0 km/h, 6.4 km/h, or 4.8 km/h on a tartan-surfaced, 1.6-km track for 24 weeks. MAIN OUTCOME MEASURES: Fitness (determined by maximal oxygen uptake) and cardiovascular risk factors (determined by resting blood pressure and serum lipid and lipoprotein levels). RESULTS: As compared with controls, maximal oxygen uptake increased significantly (P less than .0001) and in a dose-response manner (aerobic walkers greater than brisk walkers greater than strollers). In contrast, high-density lipoprotein cholesterol concentrations were not dose related and increased significantly (P less than .05) and to the same extent among women who experienced considerable improvements in their physical fitness (8.0-km/h group, +0.08 mmol/L) and those who had only minimal improvements in fitness (4.8-km/h group, +0.08 mmol/L). High-density lipoprotein cholesterol also increased among the 6.4-km/h group, but did not attain statistical significance (+0.06 mmol/L; P = .06). Dietary patterns revealed no significant differences among groups. CONCLUSION: Thus, we conclude that vigorous exercise is not necessary for women to obtain meaningful improvements in their lipoprotein profile. Walking at intensities that do not have a major impact on cardiorespiratory fitness may nonetheless produce equally favorable changes in the cardiovascular risk profile.

Adult↗
PubMed1991

Randomized study of preoperative versus postoperative radiation therapy in advanced head and neck carcinoma: long-term follow-up of RTOG study 73-03.

This is a report of a 10-year median follow-up of a randomized, prospective study investigating the optimal sequencing of radiation therapy (RT) in relation to surgery for operable advanced head and neck cancer. In May 1973, the Radiation Therapy Oncology Group (RTOG) began a Phase III study of preoperative radiation therapy (50.0 Gy) versus postoperative radiation therapy (60.0 Gy) for supraglottic larynx and hypopharynx primaries. Of 277 evaluable patients, duration of follow-up is 9-15 years, with 7.6% patients lost to follow-up before 7 years. Loco-regional control was significantly better for 141 postoperative radiation therapy patients than for 136 preoperative radiation therapy patients (p = 0.04), but absolute survival was not affected (p = 0.15). When the analysis was restricted to supraglottic larynx primaries (60 postoperative radiation therapy patients versus 58 preoperative radiation therapy patients), the difference for loco-regional control was highly significant (p = .007), but not for survival (p = 0.18). In considering only supraglottic larynx, 78% of loco-regional failures occurred in the first 2 years. Thirty-one percent (18/58) of preoperative patients failed locally within 2 years versus 18% (11/60) of postoperative patients. After 2 years, distant metastases and second primaries became the predominant failure pattern, especially in postoperative radiation therapy patients. This shift in the late failure pattern along with the increased number of unrelated deaths negated any advantage in absolute survival for postoperative radiation therapy patients. The rates of severe surgical and radiation therapy complications were similar between the two arms. Because of an increased incidence of late distant metastases and secondary primaries, additional therapeutic intervention is required beyond surgery and postoperative irradiation to impact significantly upon survival.

Adult↗
PubMed1991

The effect of local-regional control on distant metastatic dissemination in carcinoma of the head and neck: results of an analysis from the RTOG head and neck database.

A retrospective analysis of the effect of local control on the development of distant metastases was performed in 2648 patients with carcinoma of the head and neck selected from the RTOG database. The 5-year time-adjusted incidence of distant metastases was 21% for patients who were in local-regional control at 6 months after the start of treatment, compared to 38% for local-regional failure patients (p less than 0.001). The incidence of distant metastases detected between the interval of 6 months to 2.5 years after treatment was significantly increased in patients with tumors of the oral cavity, oropharynx, supraglottic larynx, and glottis who developed local-regional failure within this time period, compared to those who remained locally controlled (19% distant metastases for local-regional failure vs 7% for local-regional control (p less than 0.001)). In contrast, there as no difference in the incidence of distant metastases in patients with carcinoma of the nasopharynx or hypopharynx regardless of the local-regional disease status. A Cox proportional hazards regression analysis demonstrated that local-regional control was the most significant variable affecting the development of distant metastases, followed by tumor site, N-stage, and T-stage. For all tumor sites, except for the hypopharynx and nasopharynx, improvements in local-regional control are likely to improve survival. Tumors of the hypopharynx and nasopharynx have a higher probability of micro-metastatic dissemination at the time of initial diagnosis, and until effective methods to treat disseminated disease are developed, the effect of local control on survival will not be readily discerned.

Carcinoma, Squamous Cell↗
PubMed1991

Primary and secondary depression: a review.

The literature on the distinction between primary and secondary depression is reviewed. The research data indicate that less severe, non life-threatening suicidal thoughts and behaviours occur more often in patients with secondary depression than in those with primary depression and that the prognosis for secondary depression after somatic forms of therapy is poorer than that for primary depression. The data also suggest that secondary depressives, unlike primary depressives, suffer from chronic dysphoria. It is concluded that, because the available evidence suggests that there are no qualitative differences between the episodes of primary and secondary depression, future research should concentrate on investigating the characteristics of different groups of patients with secondary depression rather than on comparisons between primary and secondary depression in general.

Depressive Disorder↗
PubMed1991

Exercise and mild essential hypertension.

The achievement of chronic blood pressure (BP) control in persons with mild hypertension is of central strategic concern in the prevention of hypertension-related morbidity and mortality. Epidemiologic and longitudinal studies suggest that regular participation in physical activity may be beneficial both in preventing hypertension and in lowering an already elevated BP. Moreover, preliminary analyses from our center suggest that cardiorespiratory fitness and, by inference, aerobic exercise may be of benefit in reducing mortality rates in hypertensive patients. When prescribing exercise with the intention of reducing an elevated BP and attenuating the risk for coronary artery disease, several factors must be considered to optimize the likelihood of a safe and effective response. These factors include specific safety aspects, and the type, frequency, intensity, and duration of exercise. In this respect, we recommend that aerobic exercise be performed at an intensity corresponding to 55 and 85% of the maximal heart rate and that the duration and frequency of training be modulated to achieve a weekly energy expenditure of between 14 and 20 kcal/kg of body weight. For those patients who require drug therapy, the interaction between the specific antihypertensive agent and exercise must also be considered.

Antihypertensive Agents↗
PubMed1991

The role of exercise in the primary and secondary prevention of coronary artery disease.

Over the past 30 years, mortality rates from coronary artery disease (CAD) have decreased by more than 30% in the United States. However, CAD remains the major public health problem in this country. There is now substantial evidence linking exercise training to a reduced risk for CAD and for mortality after myocardial infarction. The actual mechanism by which physical activity aids in reducing the risk for developing or dying from CAD has still to be elucidated. Several highly plausible mechanisms have been postulated, including decreased myocardial oxygen demand, increased myocardial oxygen supply, reduced propensity toward ventricular arrhythmias, reduced platelet aggregation, increased plasma fibrinolytic activity, and modification of multiple CAD risk factors. Irrespective of the precise mechanism, it now appears that lower levels of physical activity are needed to reduce the risk for CAD than are needed to optimize cardiorespiratory fitness. In this regard, we recommend that the type, frequency, intensity, and duration of exercise training be modulated to achieve a weekly energy expenditure of between 14 and 20 kilocalories per kilogram of body weight. Although aerobic activities should be emphasized, muscle strengthening and flexibility exercises should also be incorporated into the training program in order to promote musculoskeletal health.

Coronary Disease↗
PubMed1991

The maximally accumulated oxygen deficit as an indicator of anaerobic capacity.

Recently, a procedure has been established for the determination of the maximally accumulated oxygen deficit (MAOD) (Medbo et al., J. Appl. Physiol. 64:50-60, 1988) as an indicator of anaerobic capacity. We hypothesized that, if MAOD were a valid indicator of anaerobic capacity, it should distinguish between aerobically and anaerobically trained athletes and correlate with other existing anaerobic testing measures. Subjects were four distance and five middle distance runners, three sprinters, and four controls. The subjects ran for 2-3 min at 125-140% of VO2max until exhaustion, and the accumulated O2 deficit for that run was calculated by an extrapolation procedure. Subjects also performed the Wingate cycle ergometer test and runs of 300, 400, and 600 m. (Only athletes performed the runs.) Post-exercise blood lactates were obtained following the supramaximal treadmill run. MAOD (in O2 equivalents-ml.kg-1) was higher for the sprinters (78) and middle distance runners (74) than for the long distance runners (56) and control subjects (56) (P less than or equal to 0.05), indicating a greater anaerobic capacity for the former two groups. Consequently, the relative anaerobic contribution was larger for the sprinters (39%) and middle distance runners (37%) than for the long distance runners (30%; P less than or equal to 0.05). Significant correlations were found between MAOD and both Wingate power and treadmill work for all subjects and between Wingate power, Wingate capacity, treadmill work, and 300 m time for the athletes, suggesting that relationships do exist among MAOD and other anaerobic test measures. Potential use of MAOD as an indicator of anaerobic capacity is therefore promising and should be further explored.

Adult↗
PubMed1990

Exercise and mild essential hypertension. Recommendations for adults.

Chronic essential hypertension is a major public health problem afflicting an estimated 15 to 30% of persons from most Western industrialised countries. Persons with mild hypertension (diastolic blood pressure between 90 and 104mm Hg and/or systolic blood pressure between 140 and 159mm Hg) represent the overwhelming majority of hypertensive individuals in the general population. The achievement of long term blood pressure control in these individuals is of central strategic concern in the prevention of hypertension-related morbidity and mortality. Epidemiological studies suggest that regular participation in physical activity may be beneficial in preventing hypertension. The findings of epidemiological studies are supported by a recent meta-analysis of 25 longitudinal aerobic training studies, in which the average sample-size-weighted reductions in resting systolic and diastolic blood pressures were 10.8mm Hg and 8.2mm Hg, respectively. Moreover, preliminary analyses from our centre suggest that cardiorespiratory fitness and, by inference, aerobic exercise training may be of benefit in reducing mortality rates in hypertensive patients. When compiling an exercise prescription with the intention of reducing an elevated blood pressure and attenuating the risk for coronary artery disease, several factors must be considered in order to optimise the likelihood of a safe and effective response. Specifically, the 5 basic components of the exercise prescription for patients with mild hypertension are safety aspects, the type of exercise to be performed, and the frequency, intensity and duration of exercise training. For those patients who require pharmacotherapy, the interaction between the specific antihypertensive agent and exercise responses must also be considered. We recommend that aerobic exercise training be performed at an intensity corresponding to 60 to 85% of the maximal heart rate and that the duration and frequency be modulated to achieve a weekly energy expenditure of between 14 and 20 kcal/kg of bodyweight.

Adult↗
PubMed1987

Fluorescent visualization of binding and internalization of the anticarcinogenic Bowman-Birk type protease inhibitors in transformed fibroblasts.

The Bowman-Birk protease inhibitors from soybeans and chick peas suppress in vitro malignant transformation. This fluorescent microscopy study is designed to visualize the cellular site of action of these protease inhibitors. Binding and internalization of active protease inhibitors occur over a time course of 2 h. The rate and character of fluorescent micrographs obtained are compared to insulin as a positive control. Internalization of both molecules is completely blocked at 4 degrees C. Interpretation of the fluorescent micrographs in conjunction with biochemical data suggests the anticarcinogenic action of Bowman-Birk type protease inhibitors may involve receptor-mediated endocytosis resulting in the internalization of both the protease inhibitors and a membrane-associated protease.

Antineoplastic Agents↗
PubMed1984

Lipid-laden macrophages in tracheal aspirates of newborn infants receiving intravenous lipid infusions: a cytologic study.

Seventy-four neonates with respiratory distress syndrome had cytologic study of tracheal aspirates. Thirteen, all of whom were receiving intravenous lipid and nothing orally had abundant macrophages with foamy cytoplasm, positive for intracytoplasmic lipid by Sudan black stain, in the tracheal aspiration specimens. Cytologic surveillance of tracheal aspiration specimens may be a useful method of monitoring infants receiving intravenous lipid infusions.

Fat Emulsions, Intravenous↗
PubMed1983

Developmental pattern of maximal transdiaphragmatic pressure in infants during crying.

Diaphragm strength was measured as maximal transdiaphragmatic pressure (Pdi) during airway occlusion in 38 infants aged 11.6 +/- 0.5 (S.E.) months postconception (mpc), range 8-21 mpc. All infants were asymptomatic at the time of study and required no mechanical ventilatory assistance. Ten infants had previous surgical correction of abdominal wall defects (gastroschisis/omphalocele); 10 infants had previous surgical correction of congenital diaphragmatic hernia; and 18 infants had no thoracic or abdominal surgery. The mean maximal Pdi for all infants was 72 +/- 3 cmH2O. There were no significant differences between the three groups. All infants with a maximal Pdi of less than 60 cmH2O were aged less than 10 mpc. After 13 mpc there was no significant increase in maximal Pdi. Between the ages 8-13 mpc there was a significant positive correlation between maximal Pdi and age postconception (r = 0.87, P less than 0.0005), reflecting a developmental pattern of increasing maximal transdiaphragmatic pressure in infants during crying.

Abdominal Muscles↗
PubMed1982

Diaphragm strength in near-miss sudden infant death syndrome.

Diaphragm muscle strength was measured as maximal transdiaphragmatic pressure during airway occlusion in ten near-miss sudden infant death syndrome infants aged 4.1 +/- 0.6 (SE) months post-term, range 2 to 7 months, and ten control infants aged 4.5 +/- 0.8 months post-term, range 0.8 to 8 months. In the near-miss sudden infant death syndrome group, the mean maximal transdiaphragmatic pressure was 106 +/- 6 cm H2O, range 78 to 132 cm H2O, compared with a mean maximal transdiaphragmatic pressure 86 +/- 4 cm H2O, range 69 to 106 cm H2O, in the control group. Diaphragm strength is normal or increased in near-miss sudden infant death syndrome infants.

Crying↗
PubMed1981

An immunohistologic study of Shope fibroma virus in rabbits: tumor rejection by cellular reaction in adults and progressive systemic reticuloendothelial infection in neonates.

The development of lesions in adult and neonatal New Zealand White rabbits following intradermal inoculation of Shope fibroma virus was studied by immunofluorescence for viral antigens. T-cells, and immunoglobulin. In adults a self-limiting local fibroxanthosarcomatous tumor was rejected within 10-12 days in association with a dense infiltration of T-cells. In neonates expanding skin lesions were associated with systemic presence of virus in the reticuloendothelial system. In surviving infected neonates, granulomas formed at the site of infection after 3 weeks. These reactions may have limited further dissemination of the virus. These results support the hypothesis that the progressive disease produced by Shope fibroma virus in neonatal rabbits may be due to the inability of the reticuloendothelial system to clear infectious virus.

Animals↗
PubMed1981

Cell-mediated immune response to Shope fibroma virus-induced tumors in adult rabbits.

The parameters of cell-mediated immune responses of adult rabbits infected with Shope fibroma virus (SFV) were characterized by measurement of the size of local draining nodes, number of cells per lymph node, mitogen responses of lymphocytes, and kinetics of virus-specific cell-mediated lymphocytotoxicity (CML). In addition, the cytolytic effector population was characterized. After intradermal injections, tumors appeared within 3-4 days, reached maximum size in 10-12 days, and then regressed completely with 24 days. The size of local popliteal lymph nodes, in particular the diffuse cortex (paracortex), and the number of cells per node increased during tumor growth but then declined as the tumor regressed. Maximum specific CML to SFV-infected kidney cell monolayers (RK-13) occurred 10 days after inoculation of SFV and correlated with the initiation of tumor regression. Adult cytotoxic lymphocytes passed through nylon wool, and most of their activity was removed by treatment with antithymocyte globulin plus complement. Cytotoxic T-cells from SFV tumor-bearing rabbits killed only targets infected with SFV and not targets uninfected or infected with vaccinia virus. Therefore, T-cell-mediated virus-specific CML appeared as a major immune effector mechanism that correlated with tumor regression. However, antibody-dependent cell-mediated and NK cytotoxicity were also demonstrable. The presence of different cell-mediated cytotoxic mechanisms suggested a heterogeneity of effector mechanism.

Animals↗
PubMed1976

In vitro studies of the rabbit immune system. V. Suppressor T cells activated by concanavalin A block the proliferation, not the induction of antierythrocyte plaque-forming cells.

The late B-cell proliferative phase of the in vitro antibody response by rabbit spleen cells is highly susceptible to suppression by activated T cells. The in vitro antisheep erythrocyte plaque-forming cell (PFC) response by spleen cells from normal or primed rabbits can be suppressed by adding concanavalin A (Con A), Con A-prestimulated peripheral blood or spleen lymphocytes, or supernates from Con A-prestimulated peripheral blood lymphocytes. The suppression is not mediated by a direct interaction of Con A with responding cells as shown by the effectiveness of prestimulated cells. Primed spleen cultures remain sensitive to Con A suppression as late as 72 h after initiation, and the addition of Con A after 24-72 h rapidly stops the increase in the number of PFC. T cells are required for Con A addition to be effective but the suppression can be induced at a time when T-helper cells are no longer necessary. Further, the suppressive effect of Con A addition is abrogated by specific antisera to rabbit T cells. We propose that Con A activates suppressor T cells which then exert their effects on proliferating PFC or their immediate precursor B cells. The early inductive or recruitment phase of the response is probably not blocked by suppressor cells. Also, there is an apparent relationship between the number of proliferating B cells and the number of suppressor cells required. Finally, the difficulties in inducing a stimulatory effect by Con A and the prolonged period that Con A addition is suppressive suggests that the rabbit has relatively more and/or longer-lived suppressor cells than the mouse and may be a particularly useful species for studying suppressive phenomena and their mechanisms.

Animals↗