PubMed Health⌕ Search

Biomedical subjects

K Casey

Publications and source records attributed to K Casey.

27 records · Page 2Linked to original sources
PubMed1987

Regulation of growth hormone during exercise by oxygen demand and availability.

Five normal men performed seven sets of seven squats at a load equal to 80% of their seven repetition maximum. Plasma growth hormone (GH) and lactate levels increased during and after the completion of the exercise. A significant (r = 0.93, P less than 0.001) linear correlation was found between GH changes and the corresponding oxygen Demand/Availability (D/A) ratio expressed by (equation; see text) (where f = [lactate at time x]/[lactate at time 0]). A retrospective examination of previously published data from our laboratory and others also demonstrated the existence of a significant correlation between changes in plasma GH levels and the D/A ratios over a wide variety of exercise; aerobic and anaerobic, continuous and intermittent, weight lifting and cycling, in both fit and unfit subjects under normoxic and hypoxic conditions. It is suggested that the balance between oxygen demand and availability may be an important regulator of GH secretion during exercise.

Growth Hormone↗
PubMed1987

The effect of exercise on the central-chemoreceptor threshold in man.

1. The threshold of the central chemoreceptors was determined under resting and three exercise conditions in four volunteers. 2. The method used was the hyperoxic, Read rebreathing technique with prior hyperventilation. Plots of resting ventilation vs. carbon dioxide consisted of two straight-line segments of different slopes above and below a breakpoint which was taken as the central-chemoreceptor threshold at rest. 3. The threshold during exercise was determined from plots of exercise ventilation vs. carbon dioxide in a similar way, but the points for these plots were obtained in a different manner. They were obtained from a number of separate rebreathing experiments, so as to avoid the divergence between mouth and central-chemoreceptor carbon dioxide levels during rebreathing in exercise. 4. Exercise was started abruptly during rebreathing experiments similar to those at rest, at a particular level of carbon dioxide, and exercise ventilation was measured at the third breath. Each rebreathing experiment therefore provides one point for the exercise ventilation vs. carbon dioxide plot. 5. The results showed that the central-chemoreceptor threshold during exercise was not different from the resting threshold, and that the initial, fast component of exercise ventilation was independent of the chemical drive to breathe.

Adult↗
PubMed1987

The effect of treadmill speed on ventilation at the start of exercise in man.

1. The change in ventilation at the start of exercise was determined during both hyperoxic rebreathing and air breathing in four volunteers. 2. In order to differentiate between the effects of limb-movement frequency and exercise load in terms of oxygen uptake, three treadmill exercises were tested: E1, at an oxygen uptake of 1 l/min on a level treadmill; E2, at 2 l/min on an inclined treadmill at the same speed as E1; E3, at 2 l/min on a level treadmill at a higher speed. All of the exercises were performed at a walking pace. 3. Prior to rebreathing, hyperventilation for 5 min to 20 mmHg was used to reduce carbon dioxide to below the central chemoreceptor threshold. From eleven to fourteen rebreathing experiments were done on each volunteer for each of the three exercises, with the treadmill started at carbon dioxide levels which ranged from 36 (below threshold) to 58 mmHg (above threshold). 4. Ten experiments were performed on each volunteer for each of the three exercises during air breathing, with the treadmill started after 5 min of rest. 5. In both the rebreathing experiments and the air breathing experiments it was found that the change in ventilation at the start of exercise was the same for exercises E1 and E2, and significantly greater for exercise E3. 6. It was concluded that the frequency of limb movement, rather than exercise load (oxygen consumption) is a determinant of the change in ventilation at the start of exercise.

Adult↗
PubMed1986

Growth hormone regulation in two types of aerobic exercise of equal oxygen uptake.

Five normal men, aged 23 to 35 years, participated in two bouts of continuous aerobic cycling separated by five days. The first type of exercise (EI) was cycling at a pedalling frequency of 50 rev X min-1 with a load which produced a steady state O2 uptake of approximately 40% of the subjects' VO2max. The second type of exercise (EII) was cycling at a pedalling frequency of 90 rev X min-1 with a load such that an equal steady state VO2 was reached and maintained. Both EI and EII lasted 40 min. GH levels increased in EI and EII, reaching their maximum at 8 min of recovery (245 and 300% of resting values, respectively). No significant differences were observed between EI and EII in GH, lactate, glucagon, insulin, cortisol and glucose levels between the two exercises. While it has been reported earlier that GH levels were frequently related to lactate levels and/or decreased O2 availability (Sutton 1977; Raynaud et al. 1981; Kozlowski et al. 1983; VanHelder et al. 1984a, b), this study suggests that the opposite is also valid, that is, different types of exercise of equal VO2, duration and lactate production do not produce significantly different GH responses.

Adult↗
PubMed1985

Hormonal and metabolic response to three types of exercise of equal duration and external work output.

Five normal men, aged 20-30 years, participated in three types of exercise (I, II, III) of equal duration (20 min) and total external work output (120-180 kJ) separated by ten days of rest. Exercises consisted of seven sets of squats with barbells on the shoulders (I; Maximal Power Output Wmax = 600-900 W), continuous cycling at 50 rev X min-1 (II; Wmax = 100-150 W) and seven bouts of intermittent cycling at 70 rev X min-1 (III; Wmax = 300-450 W). Plasma cortisol, glucagon and lactate increased significantly (P less than 0.05) during the exercise and recovery periods of the anaerobic, intermittent exercise (I and III) but not in the continuous, aerobic exercise (II). No consistent significant changes were found in plasma glucose. Plasma insulin levels decreased only during exercise II. The highest increase in cortisol and glucagon was not associated with the highest VE, VO2, Wmax or HR; however it was associated with the anaerobic component of exercise (lactic acid). It is suggested that in exercises of equal duration and total external work output, the continuous, aerobic exercise (II) led to lowest levels of glucogenic hormones.

Adult↗
PubMed1984

Seven-day activity and self-report compared to a direct measure of physical activity.

To determine how well a seven-day interview-administered activity recall used in a large epidemiologic study at Stanford University reflected seven days of self-reported activity and directly measured physical activity, 30 white males, mean age 52 years, recorded daily physical activity for a week, and half of these wore an ambulatory solid-state minicomputer (Vitalog) which measures continuous heart rate and motion. Total hours of moderate, hard, and hard plus very hard activity were not significantly different for weekdays and weekends for self-report and recall and were significantly correlated. Total energy expenditure for subjects wearing the Vitalog averaged 38.5 +/- 6.7 kcal/kg/day compared to an average of 37.7 +/- 4.5 kcal/kg/day for recall or 39.6 +/- 7.2 kcal/kg/day for self-report. Conditioning activities are best remembered followed by home or leisure and job activities. Mean hours of sleep per week night were significantly greater reported by self-report than reported by recall, but the two were significantly correlated. It is concluded that a seven-day activity recall accurately reflects mean kcal/day expenditure, with conditioning activities being the best recalled. A self-report log used in conjunction with an interview-based seven-day recall might maximize accuracy of recall.

Adult↗
PubMed1983

Use of an anal sphincter pressure monitor during operations on the sacral spinal cord and nerve roots.

The distinction of sacral roots and conus medullaris from lipoma, fibrous adhesions, and an abnormally thickened filum terminale can be difficult during operations on certain complicated dysraphic lesions. We describe a simple, noninvasive method of monitoring external anal sphincter "squeeze pressure" by means of an elongated, fluid-filled, polyethylene anal balloon connected to a pressure transducer. Cutaneous electrocardiographic (ECG) leads on both hips register the stimulus artifact from a monopolar nerve stimulator. The simultaneous display on the oscilloscope screen of the stimulus artifact and the resultant pressure response form an electromechanical coupling that allows the operator to identify a faulty stimulator probe and to distinguish true stimulus-induced external anal sphincter activity from spontaneous rhythmic contractions of the internal anal sphincter. Unilateral stimulation of the S-2, S-3, and S-4 roots generates tall pressure spikes between 40 and 75 torr in peak amplitudes, whereas S-1 and L-5 stimulation produces a stimulus artifact on the ECG but either no pressure response or a mere "ripple wave" of less than 7 torr. During operations on 11 patients with various dysraphic lesions, the S-2, S-3, and S-4 roots were identified easily and preserved, and the caudal extent of functioning neurons was localized within coni grossly distorted by intramedullary lipoma or chronic tethering. We prefer the anal sphincter pressure monitor to anal sphincter electromyography because of its simplicity, the inexpensive equipment, and its noise-free display that is virtually unaffected by other electronic systems in the operating room.

Adolescent↗
PubMedDate not supplied

Programs for families of organ and tissue donors.

Until recently, the families of patients who have given the gift of life have been the invisible group in the transplant circle. They donated the organs and tissues of their loved ones to unknown transplant recipients and then were to grieve alone. As transplantation has matured and become the treatment of choice for end stage organ failure and for other life-enhancing procedures, the importance of the donor and the donor family is being recognised and their needs and expectations identified.

Adaptation, Psychological↗