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Biomedical subjects

C Foster

Publications and source records attributed to C Foster.

At least 73 records · Page 4Linked to original sources
PubMed1981

Fifty years of training and competition in the marathon: Wally Hayward, age 70--a physiological profile.

A 70-year-old South African long-distance runner, holder of his age group's marathon record and former Olympic marathon runner, was studied to determine the effects of 52 years of regular training on functional capacity and health. Maximal treadmill exercise testing revealed no ischaemic ECG abnormalities and an excellent functional capacity (58,6 ml/kg/min). Submaximal testing showed that the subject ran at approximately 86% of maximum aerobic capacity when completing the marathon in his record time. The subject was very lean (13,6% fat) for his age. Muscles contained 82% slow-twitch fibres. Pulmonary function and blood chemical values were within normal limits. Although total cholesterol was somewhat high (247 mg/dl), high-density lipoprotein cholesterol was elevated (53 mg/dl). Twenty-four-hour Holter monitoring revealed no significant ventricular ectopic activity although frequent premature atrial contractions were noted. M-mode echocardiography revealed a normal heart with moderately hypertrophied left ventricular wall thickness. Radionuclide cine angiography showed a normal ejection fraction at rest (69%), followed by a slight drop at maximal exercise (62%). Left ventricular regional wall motion was considered normal at both rest and exercise. He had no significant orthopaedic abnormalities but showed normal flexibility and well-balanced muscular strength. Thickened heel pads were also noted. These results appear to indicate a beneficial effect of habitual physical activity upon the retention of functional capacity with ageing.

Aged↗
PubMed1981

Left ventricular function during sudden strenuous exercise.

Strenuous exercise without warm-up has been shown to produce ischemia-like electrocardiographic (ECG) abnormalities in 60-70% of healthy subjects. These abnormalities appeared to be related to the development of an unfavorable myocardial supply/demand balance and, in chronically instrumented dogs, to transient decreases in coronary blood flow. A mechanism involving subendocardial ischemia has been proposed to explain the response to sudden strenuous exercise (SSE). To determine whether the response to SSE included the development of changes in myocardial pump performance typical of ischemia, left ventricular (LV) function at rest, during graded exercise and during SSE was evaluated in nine young (26.6 +/- 3.4 years), well-trained male volunteers using first-pass radionuclide angiography. During graded exercise, the LV ejection fraction increased from 66.9 +/- 9.4% at rest to 73.0 +/- 7.1% during peak exercise, and the LV ejection rate increased from 3.36 +/- 0.67 sec-1 at rest to 6.58 +/- 1.10 sec-1 during peak exercise. Segmental wall motion was normal in all studies. During SSE, the LV ejection fraction decreased in very subject, from an average 72.2 +/- 8.6% at rst to 57.3 +/- 8.1% during exercise. The LV ejection rate remained relatively constant (3.98 +/- 0.92 sec-1 at rest vs 4.33 +/- 0.74 sec-1 during SSE). No segmental wall motion abnormalities were observed during SSE; however, LV wall motion appeared to be diffusely hypokinetic during SSE. In contrast to previous reports, few ECG abnormalities were observed during SSE. These results support the hypothesis that subendocardial ischemia is an important mechanism in the response to SSE. However, the lack of ECG changes and segmental wall motion abnormalities and the relatively high absolute value of the LV ejection fraction suggest that if subendocardial ischemia occurs during SSE, it is attributable to physiologic rather than pathologic mechanisms.

Adult↗
PubMed1980

Limb blood flow. The influence of temperature during halothane-nitrous oxide anesthesia.

Twenty adult patients were examined before anesthesia, during anesthesia, and at the end of surgery to determine the influence of body cooling on limb blood flow during prolonged halothane-nitrous oxide anesthesia. Measurements included temperature, mean arterial pressure, and leg blood flow. Cooling was prevented in ten patients by warmed anesthetic gases. The mean tympanic temperature at end of surgery was 37 degrees C for the warmed (W) and 35 degrees C for the unwarmed (UW) patients, a significant difference. The mean value for leg blood flow was significantly decreased in the UW patients (W = 5.0 vs UW = 3.1 mL/100 cc of tissue/min). These results indicate that body cooling during prolonged inhalation anesthesia was associated with a reduced limb blood flow. Therefore, pulmonary warming may be of potential benefit under similar conditions to help prevent intraoperative vascular complications.

Abdomen↗
PubMed1980

Particulate cancellous marrow crib graft reconstruction of mandibular defects.

Between 1969 and 1978 more than 1000 mandible fractures were treated by the otolaryngology services at the University of Minnesota and affiliated hospitals. Most were successfully treated but 17 patients had significant loss of mandibular bone resulting in a much more difficult management problem. The loss of bone was usually due either to the initial injury such as a gunshot wound or was secondary to the complications of non-union or osteomyelitis. Particulate cancellous marrow grafts within a Vitallium or titanium mesh crib (PCM crib graft) were used to reconstruct the mandibular defects. One patient had bilateral defects requiring 2 PCM crib grafts. Thus, 18 grafts spanning defects 2 to 12 cm were performed. Success was measured by a stable mandible with satisfactory occlusion and he ability to chew, swallow and articulate satisfactorally. Of 18 grafts, 15 met these requirements. Several factors important to successful mandibular reconstruction included adequate immobilization, intraoral soft tissue coverage, external skin cover and tension-free closure and optimal intraoral hygiene. The crib used to hold the particulate cancellous marrow in position during the healing phase has been removed in three otherwise successful cases because of intraoral mucosal tenting or dehiscence or to allow adequate fitting of dentures. In our experience, the use of autogenous cancellous bone and marrow in metallic mesh has been a successful means of restoring function and stability to mandibular defects.

Adolescent↗
PubMed1979

Training adaptations in skeletal muscle of juvenile diabetics.

Skeletal muscles from 12 male, juvenile-onset diabetics (JD) and 13 nondiabetics (ND) were studied to determine the effects of endurance training on mitochondrial enzyme activities, lipoprotein lipase (LPL) activity, and the oxidation of lipids (14C-palmityl CoA) in vitro. Ten weeks of endurance running (30 min/day, 5 days/wk) resulted in 11.0 and 12.9% gains in aerobic capacity for the JD and ND groups (P greater than 0.05), respectively. Both groups showed significant (P less than 0.05) increases in muscle LPL, carnitine palmityl transferase, succinate dehydrogenase, and hexokinase activities with training. Though the pretraining capacities for 14C-palmityl CoA oxidation were similar for both ND and JD groups, the diabetics showed a 41% greater improvement in the measurement of muscle lipid oxidation after training than did the ND group. The principal finding of this research was that skeletal muscle of juvenile diabetics who are in moderate insulin balance shows adaptations to endurance training that are similar to those of nondiabetic men.

Adult↗
PubMed1979

Effects of preexercise feedings on endurance performance.

Eight male and female students were studied during exercise to exhaustion on a bicycle ergometer at 80 and 100% of Vo2max following the ingestion of water (W), 75 g of glucose (G) or a liquid meal (M) (10 g protein, 12.5 g fat, 15 g CHO). When compared to the endurance ride (80% Vo2max) in the W treatment, endurance performance time was reduced by 19%, (p less than .05) (53.2 to 43.2 min) as a result of the preexercise glucose feeding (Trial G). No difference in performance at 80% Vo2max was found between the W and M trials. The preexercise feedings had no effect on exercise time to exhaustion at 100% Vo2max. During the G and M trials at 80% Vo2max, most of the subjects demonstrated a transient decline in serum glucose (less than 3.5 mM). After 30-40 min. of exercise, however, serum glucose returned to normal and was seldom low at the time of exhaustion. Serum free fatty acids (FFA) were depressed throughout the G trial. The results of these experiments indicate impaired lipid mobilization following CHO ingestion. The present data support our earlier findings (11) which demonstrate that glucose feedings 30-45 minutes before endurance exercise increase the rate of CHO oxidation and impede the mobilization of FFA, thereby reducing exercise time to exhaustion.

Adult↗
PubMed1978

Skeletal muscle enzyme activity, fiber composition and VO2 max in relation to distance running performance.

Muscle biopsy samples were obtained from the gastrocnemius of 26 well-trained runners of widely varying ability. Portions of the sample were analyzed for succinate dehydrogenase (SDH) activity and for muscle fiber composition. VO2 max was determined during uphill treadmill running. Mean values for muscle SDH activity (14.6 U/g), fiber composition (55% slow twitch) and VO2 max (60.9 ml/kg x min(-1)) were lower than reported previously for groups of elite and sub-elite runners. The physiological data were consistent with the performance ability of the sample [5 : 12,11 : 20 and 36 : 40 (min :s) for 1, 2 and 6 miles, respectively]. Within the sample, performance was most strongly related to VO2 max (r=-0.84,-0.87 and -0.88 for 1, 2, and 6 miles). There was little relationship between muscle SDH activity and either performance (r=-0.11, -0.14, -0.20 for 1,2, and 6 miles) or VO2 max (r=0.23). The relationship between muscle fiber composition and performance was only modestly strong (r=-0.52,-0.54, -0.55 for 1,2, and 6 miles). The results indicate that the primary determinant of cross-sectional differences in running performance is VO2 max. Skeletal muscle metabolism apparently contributes little to these cross-sectional differences and may be of much greater importance to variations in performance within an individual.

Humans↗
PubMed1978

Sequence of return of neurological function and criteria for safe ambulation following subarachnoid block (spinal anaesthetic).

Twenty-three adult men were studied during and after subarachnoid block anaesthesia for elective surgery. Measurements were obtained of mean arterial pressure and pulse, both supine and after standing for five minutes, core body (tympanic) and peripheral skin (toe) temperatures and blood flow in the leg. Time of measurements included one hour after the injection of tetracaine and after regression of the block. Results obtained indicate that the sequence of return of neurological activity following tetracaine subarachnoid block is sympathetic nervous system activity, pinprick sensation, somatic motor function followed by proprioception in the feet. This progression provides the basis for recommended criteria which indicate when it is safe for patients who have been subarachnoid block anaesthesia to become ambulatory. These criteria include: (1) return of pinprick sensation in the peri-anal area (sacral 4--5); (2) plantar flexion of the foot (while supine) at pre-anaesthetic levels of strength; and (3) return of proprioception in the big toe, always provided that the patient is not hypovolaemic or sedated.

Adult↗
PubMed1978

Prevention of post-anaesthesia shivering.

This study involves ventilation of the lungs with warmed humidifed anaesthetic gases during prolonged elective abdominal operations. Tympanic, oesophageal and toe temperatures were compared bewteen twenty warmed and twenty un-warmed patients at various times during operation and recovery. Fifty per cent (10/20) unwarmed patients shivered in the recovery room, while none of the warmed patients shivered. Our data indicate that pulmonary ventilation with warm humidified anaesthetic gases provides heat transfer by the lungs, preventing hypothermia during operation and post -anaesthesia shivering is prevented by maintaining the patient normothermic in both the operating room and the recovery room.

Anesthesia, General↗