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Biomedical subjects

S Dodd

Publications and source records attributed to S Dodd.

At least 19 recordsLinked to original sources
PubMed1992

High intensity exercise training-induced metabolic alterations in respiratory muscles.

Limited information exists concerning the effects of high intensity interval exercise training (HIET) on metabolic alterations in both inspiratory and expiratory muscles. To test the hypothesis that HIET will improve the oxidative capacity of the diaphragm and major expiratory muscles, we examined Krebs cycle and beta oxidation enzyme activities in the diaphragm and three groups of expiratory (abdominal) muscles in rats subjected to 12 weeks (5 days.wk-1) of treadmill exercise. Two groups of female Sprague-Dawley rats (age ca 120 days) were studied: (1) HIET group (n = 10; animals performed 6 x ca 5-min running intervals.day-1 at ca 90-95% VO2max); (2) sedentary control group (n = 7). When compared to controls, HIET resulted in significantly elevated (P less than 0.05) activities of 3-hydroxy-acyl-Co-A dehydrogenase (HADH) and citrate synthase (CS) in the costal diaphragm, rectus abdominus, external obliques, and the plantaris muscles. In contrast, training did not increase (P greater than 0.05) the activities of CS or HADH in the crural diaphragm or the internal obliques/transversus abdominus muscles. By comparison, the training-induced increases in oxidative capacity (e.g., CS activity) in the costal diaphragm, rectus abdominus, and external obliques were relatively small (ca 23, 10, 12%, respectively) when contrasted to the exercise-induced increase in CS activity in the plantaris muscle (ca 47%). We conclude that HIET results in small but significant improvements in the oxidative and beta oxidation capacities of the costal diaphragm and at least two abdominal expiratory muscles.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1992

Diaphragmatic fiber type specific adaptation to endurance exercise.

Recent evidence suggests that exercise training results in a significant improvement in the oxidative capacity of the mammalian diaphragm; however, limited data exist concerning which diaphragmatic fiber types are metabolically altered due to training. To test the hypothesis that exercise training increases the oxidative capacity of diaphragmatic type I and IIa fibers only, we examined the effects of endurance training on the fiber type specific changes in oxidative capacity, cross-sectional area, and capillarity of the costal diaphragm. Female Fischer-344 rats (age ca 180 days) were divided into either sedentary control group (n = 6) or an exercise training group (n = 6). The trained animals exercised for 10 wks on a motor-driven treadmill (60 min.day-1; 5 days.wk-1) at a work rate equal to ca 55-65% VO2max. Capillaries were identified histologically and fiber types determined using ATPase histochemistry. Fiber cross-sectional area (CSA) and succinate dehydrogenase (SDH) activity in individual fibers were measured using a computerized image analysis system. Compared to control animals, training did not increase the capillary to fiber ratio in any diaphragm fiber type (P greater than 0.05); however, training increased capillary density (capillary No./CSA) in type IIa fibers due to a reduction in cell CSA (P less than 0.05). Further, training resulted in significant (P less than 0.05) increases in total diaphragmatic SDH activity (delta increase = 17.5%) and an increase in SDH activity in both type I (delta increase = 14%) and IIa fibers (delta increase = 17.4%). In contrast, training did not alter (P greater than 0.05) SDH activity in type IIb fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1992

Exercise-induced cellular alterations in the diaphragm.

Limited data exist concerning the effects of exercise training on cellular oxidative capacity in the diaphragm of senescent animals. In this study we examined the changes in cellular oxidative capacity, muscle cell cross-sectional area (CSA), and capillarity within the costal diaphragm of senescent animals after a 10-wk endurance-training program. Twelve 24-mo-old female Fischer 344 rats were divided into either a sedentary control group (n = 6) or exercise training group (n = 6). The trained animals exercised on a motor-driven treadmill (60 min/day, 5 days/wk) at a work rate equal to approximately 55-65% VO2max. Capillaries were identified histologically and fiber types determined using adenosinetriphosphatase (ATPase) histochemistry. Succinate dehydrogenase (SDH) activity and CSA in individual fibers were measured using a computerized image analysis system. Exercise training did not increase (P > 0.05) the capillary-to-fiber ratio for any fiber type. However, training significantly decreased CSA (P < 0.05) and increased capillary density (capillary number/CSA) (P < 0.05) in type I, type IIa, and type IIb fibers. Furthermore, exercise training resulted in small but significant increase in SDH activity (P < 0.05) in type I and IIa fibers, whereas training did not alter SDH activity (P > 0.05) in type IIb fibers. These data demonstrate that endurance training in senescent animals results in small relative improvements in both oxidative capacity and capillary density in costal diaphragmatic type I and IIa muscle fibers. The increase in both capillary density and fiber SDH activity was largely due to a reduction in fiber CSA.

Aging↗
PubMed1992

Alterations in diaphragmatic oxidative and antioxidant enzymes in the senescent Fischer 344 rat.

We investigated age-related changes in antioxidant, glycolytic, beta-oxidation, and tricarboxylic acid cycle enzyme activity in the diaphragm and plantaris muscle of female Fischer 344 rats. Tissue samples from the costal and crural diaphragm and plantaris muscle were obtained from 30 animals in the following age groups: 1) 6 mo old (n = 10), 2) 26 mo old (n = 10), and 3) 30 mo old (n = 10). Aging had no effect (P greater than 0.05) on the activities of citrate synthase (CS) and 3-hydroxyacyl-CoA dehydrogenase (HADH) in the costal or crural diaphragm. Similarly, no age-related differences existed (P greater than 0.05) in the crural diaphragm in lactate dehydrogenase (LDH) or glutathione peroxidase (GPX) activity. In contrast, the activities of LDH and GPX were significantly (P less than 0.05) higher in the costal diaphragm in the 30- than in the 6-mo old animals. In addition, the ratio of LDH to CS activity increased (P less than 0.05) as a function of age in the costal diaphragm. Conversely, the ratio of CS to GPX activity in the costal diaphragm was lower (P less than 0.05) in the 30- than in the 6-mo old animals. No significant (P greater than 0.05) age-related differences existed in LDH-to-CS or CS-to-GPX activity ratios in the crural diaphragm. Finally, aging resulted in a significant decrease (P less than 0.05) in the activities of LDH, CS, and HADH in the plantaris muscle. These data demonstrate that, unlike many hindlimb locomotor muscles, the oxidative capacity of the Fischer 344 rat diaphragm does not decrease in old age.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1992

Endurance training-induced increases in expiratory muscle oxidative capacity.

Recent evidence demonstrates that endurance exercise training improves the oxidative capacity of the major mammalian inspiratory muscle (e.g., costal diaphragm). In contrast, no data exist concerning the effects of exercise training on abdominal expiratory muscles. We tested the hypothesis that 12 wk of endurance exercise training would significantly increase the activity of selected beta oxidation and Krebs cycle enzymes of abdominal expiratory muscles of the rat. To test this hypothesis two groups of female Sprague-Dawley rats were studied: group 1, continuous exercise training (n = 13); and group 2, sedentary control (n = 6). Exercise trained animals ran 5 d.wk-1 on a motorized treadmill for 45 min.d-1 at approximately 75-80% VO2max. When compared with controls, exercise training resulted in elevated (P less than 0.05) activities of 3-hydroxy-acyl-Co-A dehydrogenase (HADH) and citrate synthase (CS) in two abdominal expiratory muscles (rectus abdominus and external obliques). In contrast, training did not alter (P greater than 0.05) CS or HADH activity in the internal obliques/transversus abdominus muscles. In general, the training-induced increases in expiratory muscles CS activity were relatively small (approximately 10-13%) when compared with the training-induced increase in CS activity in the plantaris muscle (approximately 44%). These data demonstrate that continuous exercise training results in small but statistically significant improvements in the oxidative and beta oxidation capacities of expiratory muscles.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1991

Age-related changes in enzyme activity in the rat diaphragm.

Limited data exist concerning the effect of growth and aging on the metabolic properties of the diaphragm. Therefore, we investigated age-related changes in protein concentration and glycolytic and Krebs cycle enzyme activity in the diaphragm as well as the plantaris muscle of female Sprague-Dawley rats ranging in age from 1 to 12 months. Samples from the costal and crural diaphragm and the plantaris muscle were obtained from 38 animals in the following age groups: (1) 1 month old (N = 7); (2) 4 month old (N = 6) (3) 6 month old (N = 13); and (4) 12-month-old (N = 12). Body weight and diaphragm weight increased rapidly by a factor of 6 and in parallel during 1-4 months postpartum before reaching a plateau at 6 months of age. No significant difference (P greater than 0.05) existed in the ratio of diaphragm weight to body weight among age groups. Protein concentration was significantly higher (P less than 0.05) in the costal diaphragm and plantaris at 4 and 6 months when compared to 1 and 12 months of age. In the crural diaphragm, protein concentration was significantly lower (P less than 0.05) at 1 month postpartum when compared to all other age groups. Succinate dehydrogenase (SDH) activity was significantly higher (P less than 0.05) at 1 month of age in the plantaris, the costal diaphragm and the crural diaphragm when compared to older animals. In contrast, the activity of lactate dehydrogenase (LDH) in the plantaris, the costal diaphragm and the crural diaphragm was significantly lower (P less than 0.05) in the 1-month-old animals when compared to all other ages.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1991

Evidence for an alveolar-arterial PO2 gradient threshold during incremental exercise.

Examination of the alveolar-to-arterial O2 tension (A-a PO2 difference) provides a method of examining the efficiency of pulmonary gas exchange during exercise. At present, considerable confusion exists as to the exact pattern of the A-a PO2 difference during incremental exercise. We tested the hypothesis that the A-a PO2 difference during incremental exercise is alinear with respect to metabolic rate. Measurements of the A-a PO2 difference were made on six healthy male subjects during incremental exercise under sea level conditions (PIO2 = 149 torr). An alinear model best described the relationship between the A-a PO2 difference and metabolic rate; only small increases in the A-a PO2 difference occurred at low work rates followed by a rapid increase at higher work rates. The existence of a "A-a PO2 difference threshold" was mathematically confirmed by the use of a computer algorithm to define inflection points. These data provide evidence that the relationship between the A-a PO2 difference and metabolic rate is alinear and that a metabolic threshold exists for a rapid increase in the A-a PO2 difference. We conclude that the efficiency of pulmonary gas exchange during exercise is unaltered from rest during low-to-moderate power outputs, however, high intensity exercise compromises pulmonary gas exchange efficiency as evidenced by a significant widening of the A-a PO2 difference.

Adult↗
PubMed1991

Effects of self-monitored exercise on selected blood chemistry parameters of end-stage renal disease patients.

The effects of exercise on patients with end-stage renal disease (ESRD) is relatively unexplored. Of the complications associated with kidney failure, anemia and abnormal blood lipids profiles are among those that exercise may alter. Thus, the purpose of this study was to determine the effects of a self-monitored exercise program on the blood chemistry status in ESRD patients. The program consisted of aerobic activity maintained for a minimum of 15 min at least three times per week at an intensity of 10.8 +/- 2.13 on the Borg rating of perceived exertion scale (this scale correlates with heart rate and is used in cases where heart rate is not a reliable predictor of exercise intensity such as hemodialysis patients). Monthly blood samples were taken to assess the patients status regarding anemia and blood lipids. Results indicate no significant differences (P greater than 0.05) were seen from the beginning of the program until the end of the eighth month as seen below: [table; see text] Values are X +/- SEM. These data indicate that a self-monitored exercise program of moderate intensity may not be beneficial in helping regulate the anemia and altered blood lipid status of ESRD patients. Thus, since no physiological benefits are apparent with a self-monitored exercise program of low intensity, it is important to realize the potential risk involved with patients undertaking an unsupervised exercise program. These data illustrate that ESRD patients need supervised exercise programs in order to elicit a physiological training response.

Adult↗
PubMed1991

Influence of a carbohydrate-electrolyte beverage on performance and blood homeostasis during recovery from football.

This study compared the efficacy of a 7% glucose polymer beverage containing electrolytes (GP) versus a nonnutrient, nonelectrolyte placebo (P) in maintaining blood homeostasis during recovery from football and determined whether consumption of the GP beverage improved anaerobic performance immediately after football competition when compared with the placebo. Forty-four high school football players participated in a 50-play scrimmage designed to simulate game conditions. At each of six periods before and during the scrimmage, players consumed 170 ml of the GP or P beverage. Eight maximal-effort 40-yd sprints (40-sec rest intervals) were performed before and after the scrimmage to assess the decrement in anaerobic performance from the scrimmage. Venous blood samples were drawn before and after the scrimmage and analyzed. The pre- to postscrimmage differences in mean and peak sprint velocities did not differ between treatments, nor did body weight and plasma. In contrast, the percent decrease in plasma volume was significantly greater in the P group. Postscrimmage increases in glucose and insulin were greater in the GP group. These data suggest that CHO-electrolyte drinks do not prevent a decline in anaerobic performance when compared to water, but a CHO-electrolyte drink is more effective in maintaining PV than water during recovery from anaerobic exercise.

Adolescent↗
PubMed1991

Factors affecting adherence of end-stage renal disease patients to an exercise programme.

Recently it has been shown that regular exercise is both physiologically and psychologically beneficial to patients with end-stage renal disease (ESRD). However, ESRD patients traditionally have a high non-adherence level to their self-care and medical regimens. To date, their adherence to exercise programmes has not been studied. Background information about employment, medical history, previous exercise habits and locus of control was obtained from 40 volunteer ESRD patients who started exercise at home. Twenty-eight participants maintained the exercise programme, consisting of aerobic activity lasting an average of 25 min, four times per week, for 12 weeks. The adherent patients were found to have encouraging support groups (75 versus 25%), to be between 41 and 60 years of age (64 versus 33%), to have been on dialysis for between 2 and 5 years, and to have loci of control (feeling of control over life events) classed as 'internal' (68 versus 25%). Factors such as sex, race, employment status and depression were found to have little influence on adherence. The major finding of this study was that patients adherent to exercise could be distinguished by unique psychological and psychosocial factors, and that adherence in this population was higher (70 compared with 50%) than some estimates for the general population.

Adult↗
PubMed1990

Fluid replacement drinks during high intensity exercise: effects on minimizing exercise-induced disturbances in homeostasis.

The purpose of these experiments was to examine the influence of various fluid replacement drinks on exercise-induced disturbances in homeostasis during heavy exercise. Nine trained cyclists performed constant load exercise on a cycle ergometer to fatigue on three occasions with 1-week separating experiments. The work rate was set initially at approximately 85% of VO2max (range 82-88%) with fatigue being defined as a 10% decline in power output below the initial value. During each experiment subjects consumed one of the following three beverages prior to and every 15 min during exercise: (1) non-electrolyte placebo (NEP; 31 mosmol.kg-1); (2) glucose polymer drink containing electrolytes (GP; 7% CHO, 231 mosmol.kg-1), and (3) electrolyte placebo drink without carbohydrate (EP; 48 mosmol.kg-1). Both the GP and EP beverage contained sodium citrate/citric acid (C) as a flavoring agent while C was not contained in the NEP drink. Although seven of nine subjects worked longer during the GP and EP treatment when compared with the NEP trial, the difference was not significant (P greater than 0.05). No differences (P greater than 0.05) existed between the GP and EP treatments in performance time. Exercise changes in rectal temperature, heart rate, delta % plasma volume and plasma concentrations of total protein, free fatty acids, glucose, lactate, potassium, chloride, calcium, and sodium did not differ (P greater than 0.05) between trials.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Endurance-training-induced cellular adaptations in respiratory muscles.

Controversy exists concerning the adaptability of mammalian respiratory muscles in response to endurance training. We examined the effects of 8 wk of progressive treadmill exercise (45 min/day 5 days/wk) on the biochemical adaptations of rat diaphragm and intercostal muscles. Female Sprague-Dawley rats were randomly assigned to a sedentary control (n = 10) or an exercise-training group (n = 10). Endurance training resulted in an enhanced oxidative capacity in the anterior costal diaphragm as evidenced by a 29% increase (P less than 0.05) in the activity of succinate dehydrogenase (SDH) in trained animals compared with controls (4.15 +/- 0.13 vs. 3.21 +/- 0.17 mumol.g-1.min-1). Similarly, SDH activity in the intercostal muscles was 32% greater (P less than 0.05) in the trained animals than in the untrained animals (1.72 +/- 0.11 vs. 1.30 +/- 0.06 mumol.g-1.min-1). In contrast, the crural region of the diaphragm showed no significant increase (P greater than 0.05) in oxidative capacity as a result of the training program (3.28 +/- 0.12 vs. 3.13 +/- 0.18). Furthermore, training did not alter (P less than 0.05) lactate dehydrogenase activity in the intercostals or in the crural or the costal diaphragm. These data demonstrate that the oxidative capacity of the costal diaphragm and the intercostal muscles can be enhanced by increasing respiratory loads via regular endurance exercise. We speculate that the lack of metabolic adaptation in the crural region of the diaphragm was not due to limited plasticity of the fibers in this area but to failure to the exercise-training program to provide the appropriate stimulus for cellular adaptation.

Adaptation, Physiological↗
PubMed1990

Multiple myeloma in pregnancy: a case report.

We report here a 33-year-old patient found at 20 weeks' gestation to be anemic and to have both a serum M-protein (immunoglobulin [Ig]G kappa) and a kappa-type urinary Bence Jones protein. The concentration of these proteins, measured during pregnancy and in the postpartum period, demonstrated the presence of the maternal serum IgG kappa component in the amniotic fluid and its transmission to, and eventual disappearance from, the newborn.

Bence Jones Protein↗
PubMed1989

Rhabdomyosarcoma in children: a histological and immunohistochemical study of 59 cases.

Recent studies have suggested that rhabdomyosarcoma can be divided into favourable and unfavourable histology groups. Those subtypes comprising the unfavourable histology group are alveolar, monomorphous round cell and anaplastic rhabdomyosarcoma, with a favourable histology group of embryonal rhabdomyosarcomas. An immunohistological study was undertaken on 59 childhood rhabdomyosarcomas, using antisera to keratin, S100 protein, vimentin, desmin, myoglobin, and troponin T. Our results suggest that desmin is the single most useful antibody in the diagnosis of rhabdomyosarcoma and was expressed in all our cases. The expression of troponin T in the majority of embryonal rhabdomyosarcomas but not in the other histological types has prognostic implications.

Child↗
PubMed1989

Effects of incomplete pulmonary gas exchange on VO2 max.

Recent evidence suggests that heavy exercise may lower the percentage of O2 bound to hemoglobin (%SaO2) by greater than or equal to 5% below resting values in some highly trained endurance athletes. We tested the hypothesis that pulmonary gas exchange limitations may restrict VO2max in highly trained athletes who exhibit exercise-induced hypoxemia. Twenty healthy male volunteers were divided into two groups according to their physical fitness status and the demonstration of exercise-induced reductions in %SaO2 less than or equal to 92%: 1) trained (T), mean VO2max = 56.5 ml.kg-1.min-1 (n = 13) and 2) highly trained (HT) with maximal exercise %SaO2 less than or equal to 92%, mean VO2max = 70.1 ml.kg-1.min-1 (n = 7). Subjects performed two incremental cycle ergometer exercise tests to determine VO2max at sea level under normoxic (21% O2) and mild hyperoxic conditions (26% O2). Mean %SaO2 during maximal exercise was significantly higher (P less than 0.05) during hyperoxia compared with normoxia in both the T group (94.1 vs. 96.1%) and the HT group (90.6 vs. 95.9%). Mean VO2max was significantly elevated (P less than 0.05) during hyperoxia compared with normoxia in the HT group (74.7 vs. 70.1 ml.kg-1.min-1). In contrast, in the T group, no mean difference (P less than 0.05) existed between treatments in VO2max (56.5 vs. 57.1 ml.kg-1.min-1). These data suggest that pulmonary gas exchange may contribute significantly to the limitation of VO2max in highly trained athletes who exhibit exercise-induced reductions in %SaO2 at sea level.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Accuracy of pulse oximetry to estimate HbO2 fraction of total Hb during exercise.

The accuracy of two pulse oximeters (Ohmeda 3700 and Biox IIa) was evaluated during cycle ergometer incremental exercise in 10 healthy subjects. The exercise protocol began at 30 W with the power output being increased 15 W.min-1 until volitional fatigue. Ear and finger probe pulse oximetry measurements of available hemoglobin (%Spo2) were compared with arterial oxyhemoglobin fraction of total hemoglobin (%HbO2) measured directly from arterial blood samples using a CO-oximeter. To provide a wide range of %HbO2 values, four subjects exercised under hypoxic conditions [inspired partial pressure of O2 (PIo2) = 107 Torr], while the remaining six subjects exercised under normoxic conditions (PIo2 = 150 Torr). Because carboxyhemoglobin (HbCO) or methemoglobin (MetHb) is not measured by pulse oximeters, %HbO2 was corrected for HbCO and MetHb and expressed as percent arterial O2 saturation of available Hb (%Sao2). Small and insignificant differences (P greater than 0.05) existed between SpO2 (all 3 instruments) and %SaO2 at the lowest work rate and the highest power output achieved. Regression analyses of %SpO2 vs. %SaO2 produced correlation coefficients of r = 0.82 [standard error of the estimate [(SEE) = 1.79], r = 0.89 (SEE = 1.48), and r = 0.93 (SEE = 1.14) for the Biox IIa, Ohmeda 3700 (ear), and the Ohmeda 3700 (finger) pulse oximeters, respectively. We conclude that pulse oximetry, within the above limits of accuracy, is useful in estimating %SaO2 during exercise in healthy subjects.

Adult↗