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PubMed2004

Effect of prior multiple-sprint exercise on pulmonary O2 uptake kinetics following the onset of perimaximal exercise.

We hypothesized that the metabolic acidosis resulting from the performance of multiple-sprint exercise would enhance muscle perfusion and result in a speeding of pulmonary oxygen uptake (VO2)kinetics during subsequent perimaximal-intensity constant work rate exercise, if O2 availability represented a limitation to VO2 kinetics in the control (i.e., no prior exercise) condition. On two occasions, seven healthy subjects completed two bouts of exhaustive cycle exercise at a work rate corresponding to approximately 105% of the predetermined Vo2 peak, separated by 3 x 30-s maximal sprint cycling and 15-min recovery (MAX1 and MAX2). Blood lactate concentration (means +/- SD: MAX1: 1.3 +/- 0.4 mM vs. MAX2: 7.7 +/- 0.9 mM; P < 0.01) was significantly greater immediately before, and heart rate was significantly greater both before and during, perimaximal exercise when it was preceded by multiple-sprint exercise. Near-infrared spectroscopy also indicated that muscle blood volume and oxygenation were enhanced when perimaximal exercise was preceded by multiple-sprint exercise. However, the time constant describing the primary component (i.e., phase II) increase in VO2 was not significantly different between the two conditions (MAX1: 33.8 +/- 5.5 s vs. MAX2: 33.2 +/- 7.7 s). Rather, the asymptotic "gain" of the primary Vo2 response was significantly increased by the performance of prior sprint exercise (MAX1: 8.1 +/- 0.9 ml.min(-1).W(-1) vs. MAX2: 9.0 +/- 0.7 ml.min(-1).W(-1); P < 0.05), such that VO2 was projecting to a higher "steady-state" amplitude with the same time constant. These data suggest that priming exercise, which apparently increases muscle O2 availability, does not influence the time constant of the primary-component VO2 response but does increase the amplitude to which VO2 may rise following the onset of perimaximal-intensity cycle exercise.

Adaptation, Physiological↗
PubMed2006

Relationship between repetitive work and the prevalence of carpal tunnel syndrome in part-time and full-time female supermarket cashiers: a quasi-experimental study.

OBJECTIVES: To investigate the prevalence of Carpal Tunnel Syndrome (CTS) in full-time and part-time supermarket cashiers exposed to a different weekly duration of biomechanical load. METHODS: All the 269 cashiers and 127 office workers were asked to participate. The protocol included ergonomic risk assessment, collection of personal and clinical data and bilateral electrodiagnostic study of the median nerve. CTS symptoms were defined as past and/or current nocturnal and/or diurnal numbness, tingling, burning or pain involving at least one of the first three fingers. Results were evaluated according to two case definitions based on current symptoms and on the combination of current symptoms and slowing of sensory conduction velocity from wrist to palm, respectively. Difference in proportions of CTS symptoms and cases was evaluated by the Pearson's chi-square (chi(2)) test, univariate and multivariate logistic regression analyses were performed to determine the impact of weekly exposure. RESULTS: The final female study population included 71 full-time cashiers, 155 part-time cashiers and 98 office workers. Ergonomic risk level was rated 5 for hand activity level and 4 for peak of force according to ACGIH. The intersection of the two values fell on the threshold limit value line, confirming the possible exposure to biomechanical risk factors for CTS. The prevalence of current CTS symptoms was higher among full-time (31.0%) than in part-time cashiers (19.3%) or controls (16.3%) (p = 0.055). A similar pattern was found for CTS past symptoms and cases. Univariate analysis showed that full-time cashiers had a 2.3 fold increased risk for CTS specific current symptoms than control subjects. A similar trend also emerged for CTS cases but was not significant (Odds ratios 1.23). Multivariate logistic regression analysis confirmed the increased risk for CTS current symptoms in full-time cashiers. CONCLUSIONS: Intensive manual work associated with inadequate recovery time might have generated an impairment of the median nerve at the wrist level proportionally increasing with duration of hand use. Our study can provide useful information both for ergonomic risk assessment and work organization.

Adult↗
PubMed1991

Maturation of ventilatory responses to 1-minute exercise.

To test the hypothesis that ventilatory responses to exercise mature during growth in healthy children, we examined CO2 production (VCO2) and minute ventilation (VE) before, during, and for 10 min after 1-min bursts of cycle ergometry exercise. Ten children (range: 7-11 y old) and 13 adults (26-42 y old) exercised at work rates corresponding to 50 and 80% of the anaerobic or lactate threshold, 50% of the difference between anaerobic threshold and maximum O2 consumption, 100% of maximum O2 consumption, and 125% of maximum O2 consumption (125% max). Gas exchange was measured breath by breath. Children recovered faster from high-intensity (above anaerobic threshold) exercise as judged by the time constant of single exponential curve-fits to postexercise VCO2 [55 +/- 10 s (1 SD) at 125%. max in children compared with 92 +/- 17 s at 125% max in adults; p less than 0.001] and VE (58 +/- 10 s at 125% max in children compared with 125 +/- 37 s in adults, p less than 0.001). Although we found no significant difference between VCO2 and VE recovery times in children, VE was significantly slower than VCO2 in adults for high-intensity exercise. Moreover, recovery times in adults increased with work intensity but were independent of them in children. Whereas the CO2 costs [calculated as total CO2 produced above baseline per unit work done (mL.J-1)] increased with work intensity in adults, no similar significant relationship was observed in children.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2004

Effect of heliox on lung dynamic hyperinflation, dyspnea, and exercise endurance capacity in COPD patients.

We tested the hypothesis that heliox breathing, by reducing lung dynamic hyperinflation (DH) and dyspnea (Dys) sensation, may significantly improve exercise endurance capacity in patients with chronic obstructive pulmonary disease [n = 12, forced expiratory volume in 1 s = 1.15 (SD 0.32) liters]. Each subject underwent two cycle ergometer high-intensity constant work rate exercises to exhaustion, one on room air and one on heliox (79% He-21% O2). Minute ventilation (VE), carbon dioxide output, heart rate, inspiratory capacity (IC), Dys, and arterial partial pressure of CO2 were measured. Exercise endurance time increased significantly with heliox [9.0 (SD 4.5) vs. 4.2 (SD 2.0) min; P < 0.001]. This was associated with a significant reduction in lung DH at isotime (Iso), as reflected by the increase in IC [1.97 (SD 0.40) vs. 1.77 (SD 0.41) liters; P < 0.001] and a decrease in Dys [6 (SD 1) vs. 8 (SD 1) score; P < 0.001]. Heliox induced a state of relative hyperventilation, as reflected by the increase in VE [38.3 (SD 7.7) vs. 35.5 (SD 8.8) l/min; P < 0.01] and VE/carbon dioxide output [36.3 (SD 6.0) vs. 33.9 (SD 5.6); P < 0.01] at peak exercise and by the reduction in arterial partial pressure of CO2 at Iso [44 (SD 6) vs. 48 (SD 6) Torr; P < 0.05] and at peak exercise [46 (SD 6) vs. 48 (SD 6) Torr; P < 0.05]. The reduction in Dys at Iso correlated significantly (R = -0.75; P < 0.01) with the increase in IC induced by heliox. The increment induced by heliox in exercise endurance time correlated significantly with resting increment in resting forced expiratory in 1 s (R = 0.88; P < 0.01), increase in IC at Iso (R = 0.70; P < 0.02), and reduction in Dys at Iso (R = -0.71; P < 0.01). In chronic obstructive pulmonary disease, heliox breathing improves high-intensity exercise endurance capacity by increasing maximal ventilatory capacity and by reducing lung DH and Dys.

Administration, Inhalation↗
PubMed2000

Physical activity surveillance in the 21(st) century.

PURPOSE: The 1996 Surgeon General's Report on Physical Activity and Health emphasized the health-related benefits of moderate-intensity physical activities, especially everyday activities. Unfortunately most surveillance systems in the U.S. primarily measure sports-related activities, particularly vigorous intensity sports. This report describes a new physical activity surveillance instrument designed to go beyond our current measures and include moderate-intensity everyday activities.METHODS: Data were collected from a nationally representative sample of adults (n = 5010). Questions were asked about occupational activity (mostly sitting; mostly walking; mostly heavy labor); walking (for exercise, transportation, or any other reason); moderate-intensity activities (brisk walking, yard work, vacuuming); vigorous-intensity activities (running, aerobics, heavy yard work); and strengthening activities (lifting weights, pull-ups, sit-ups). Questions included frequency and duration of activities. Respondents were defined as recommended if they participated in either moderate-intensity activities >/=30 min/day for >/=5 days/wk OR vigorous-intensity activities >/=20 min/day for >/=3 days/wk. Insufficient was defined as not meeting recommended levels while inactive was defined as no leisure-time activity.RESULTS: Overall 40% of adults were in the recommended group, 44% were in the insufficient group and 16% were inactive. Among working adults 37% had jobs that involved mostly walking or heavy labor and about 50% of those also were in the recommended group. Among the 63% of working adults who report mostly sitting at work, 39% were in the recommended group.CONCLUSIONS: These results suggest that measuring only leisure-time physical activity may under represent the physical activity experience of many U.S. adults. Broadening the concept of physical activity beyond traditional sports-related vigorous "exercise" may provide a more accurate picture of the prevalence of health-related physical activity.

Journal Article↗
PubMedDate not supplied

Chemiluminescence ELISA for the detection of antibodies to bovine leukaemia virus antigens.

A chemiluminescence enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to bovine leukaemia virus antigens (BLV) has been developed. The possibility of using an enhanced chemiluminescence reaction for the determination of adsorbed immunoperoxidase conjugates was studied in this work. The intensity of chemiluminescence depends on both the concentration of reagents and experimental conditions used. The efficiency of the assay is determined by the formation of an immobilized antigen monolayer. A relationship between the quantity of the protein added and adsorbed has been shown. The optimal time and temperature for the antigen-antibody incubation steps have been estimated for each system (3 h at 37 degrees C was chosen as a standard incubation time). A linear dependence of the chemiluminescence intensity and optical density on the concentration of antibodies to the BLV antigens was observed. The detection limit of antibodies in the chemiluminescence ELISA is 2-3 times lower than that in the spectrophotometric one. The results obtained indicate the possibility of using both methods.

Animals↗
PubMedDate not supplied

Chemiluminescent immunoassay (CLIA) for the detection of brucellosis and tularaemia antigens.

The detection of brucellosis and tularaemia infection agents is of particular interest for medical practice. The possibility of using enhanced chemiluminescence reactions for the determination of these agents is studied in this work. Light intensity depends on both the conjugate concentration used and the conditions at which the adsorption was performed. Optimal conditions for these test-systems were: approximately 20 micrograms/mL of Ig and 200 micrograms/mL (titre 1:20) of conjugate. As is seen from the chemiluminescent and spectrophotometric results the lowest determined concentrations are 10 and 30 ng/mL (for brucellosis) and 1 and 5 ng/mL (for tularaemia), respectively. Calibration curves in the antigen concentrations ranging from 10 to 2500 ng/mL (for brucellosis) and from 1 to 500 ng/mL (for tularaemia) are observed. Optical density depends linearly on the logarithm of the antigen concentration from 30 to 5000 ng/mL (for brucellosis) and from 5 to 250 ng/mL (for tularaemia). The results obtained permit the conclusion that the chemiluminescence method can be used in enzyme immunoanalysis for brucellosis and tularaemia antigens.

Animals↗
PubMedDate not supplied

MRP1/GS-X pump ATPase expression: is this the explanation for the cytoprotection of the heart against oxidative stress-induced redox imbalance in comparison to skeletal muscle cells?

Striated muscle activity is always accompanied by oxidative stress (OxStress): the more intense muscle work and/or its duration, the more a redox imbalance may be attained. In spite of cardiac muscle functioning continuously, it is well known that the heart does not suffer from OxStress-induced damage over a broad physiological range. Although the expression of antioxidant enzymes may be of importance in defending heart muscle against OxStress, a series of combined antioxidant therapeutic approaches have proved to be mostly ineffective in avoiding cellular injury. Hence, additional mechanisms may be involved in heart cytoprotection other than antioxidant enzyme activities. The strong cardiotoxic effect of doxorubicin-induced cancer chemotherapy shed light on the possible role for multidrug resistance-associated proteins (MRP) in this context. Muscle activity-induced 'physiological' OxStress enhances the production of glutathione disulfide (GSSG) thus increasing the ratio of GSSG to glutathione (GSH) content inside the cells, which, in turn, leads to redox imbalance. Since MRP1 gene product (a GS-X pump ATPase) is a physiological GSSG transporter, adult Wistar rats were tested for MRP1 expression and activity in the heart and skeletal muscle (gastrocnemius), in as much as the latter is known to be extremely sensitive to muscle activity-induced OxS. MRP1 expression was completely absent in skeletal muscle. In contrast, the heart showed an exercise training-dependent induction of MRP1 protein expression which was further augmented (2.4-fold) as trained rats were challenged with a session of acute exercise. On the other hand, inducible expression of the 70-kDa heat shock protein (HSP70), a universal marker of cellular stress, was completely absent in the heart of sedentary and acutely exercised rats, whereas skeletal muscle showed a conspicuous exercise-dependent HSP70 expression, which decreased by 45% with exercise training. This effect was paralleled by a 58% decrease in GSH content in skeletal muscle which was even higher (an 80%-fall) after training thus leading to a marked redox imbalance ([GSSG]/[GSH] raised up to 38-fold). In the heart, GSH contents and [GSSG]/[GSH] ratio remained virtually unchanged even after exercise challenges, while GS-X pump activity was found to be 20% higher in the heart related to skeletal muscle. These findings suggest that an intrinsic higher capacity to express the MRP1/GS-X pump may dictate the redox status in the heart muscle thus protecting myocardium by preventing GSSG accumulation in cardiomyocytes as compared to skeletal muscle fibres.

Adenosine Triphosphatases↗
PubMed2001

Absolute Intensities of the 10-µm Bands of (16)O(3).

Two hundred ninety experimental absolute intensities of nu(1) and nu(3) transitions of ozone have been measured, with good accuracy (<2%). They are used to derive the transition-moment parameters for these bands. The agreement between our observed and calculated line intensities is satisfactory. This work shows that the intensities of these two bands are on average 4% smaller than those used in the literature. In addition, 20 intensities of the nu(2) + nu(3) - nu(2) band confirm this value. Also, 42 line intensities of the 2nu(1)-nu(3) band are reported. Copyright 2001 Academic Press.

Journal Article↗
PubMed1987

Transcutaneous monitoring of PO2 and PCO2 during running--a noninvasive determination of gas transport.

Transcutaneous pO2 and pCO2 (tcpO2 and tcpCO2) were measured during running with stepwise increased velocities and with constant speed, under both aerobic and anaerobic conditions, for the determination of blood gas transport during exercise. Arterial and transcutaneous blood gas values correlated significantly (pO2 r = 0.87, p less than 0.001, pCO2 r = 0.91, p less than 0.001 respectively). Transcutaneous pCO2 is a noninvasive method of monitoring arterial pCO2 and lactate formation during exercise. When athletes run, arterial pO2 falls to a specific limit depending on the intensity of work. This seems to be characteristic for maximum oxygen transport capacity. The aerobic endurance measured by the aerobic-anaerobic threshold may be dependent on the possibility of sustaining low arterial pO2 during high working levels at high oxygen consumption.

Blood Gas Monitoring, Transcutaneous↗
PubMed1988

Pulmonary mechanics during treadmill exercise in race ponies.

Exercise-induced variations in their ventilatory mechanics were studied in 8 healthy ponies 4.2 +/- 1.4 years old and weighing 282 +/- 11 kg. Airflow (V), tidal volume (VT), esophageal pressure, mask pressure and electrocardiogram were simultaneously recorded before, during and after a treadmill (incline 8.3 degrees) exercise which consisted of 2 min walking (1.5 m.sec-1), 3 min slow trotting (3.0 m.sec-1) and 3 min fast trotting (3.5 m.sec-1). The results of three consecutive daily measurements were averaged for each pony. Heart rate, minute volume (Ve), respiratory frequency (f) and peak inspiratory and expiratory V, mean inspiratory and expiratory V, and peak to peak changes in transpulmonary pressure (maxdPtp) increased linearly and significantly with increasing velocity (v) (R2 = 0.99). Tidal volume and the inspiratory time to total breathing time ratio showed a curvilinar relation with v (R2 = 0.99). Minute volume, maxdPtp, total pulmonary resistance (RL) and VT increased from rest to fast trot 6.7, 5.7, 1.5 and 1.6 times respectively. When the ponies stopped all these values decreased significantly. After 5 min recovery, the Ve was approximately doubled, VT and max dPtp unchanged and RL 30% smaller than their respective resting values. The exercise-induced increase in Ve was achieved by an increase in f at both low and high intensity of work.

Animals↗
PubMed1980

Plasma AVP, neurophysin, renin activity, and aldosterone during submaximal exercise performed until exhaustion in trained and untrained men.

The effect of intense muscular work (80% of maximal oxygen uptake) on responses of plasma hormones involved in electrolyte and water balance were measured in 14 male subjects. They were divided into three groups according to their maximal oxygen uptake and the duration of exercise performed until exhaustion: well trained subjects (group I), trained subjects (group II), and untrained subjects (group III). Pulmonary gas exchange, heart rate, rectal and skin temperature, and weight loss were measured as well as hematocrit and plasma and urine sodium and potassium concentrations. Rectal temperature increased significantly in all subjects after exhaustion. The variation of hematocrit was smallest and the weight loss greatest in the well-trained subjects. Plasma aldosterone, renin activity (PRA), vasopressin (AVP), and neurophysin (Np) displayed highly significant increases after exercise in all three groups: PRA was increased 4.5 times (p < 0.01), aldosterone 13 times (p < 0.05), Np 2.6 times (p pe 0.05), and AVP 4.8 times (p < 0.05). Nevertheless, there was no correlation between the changes in PRA and those in plasma aldosterone, nor between aldosterone and plasma sodium or potassium. At the urinary level, the only striking observation was that free water clearance tends to become positive after exercise. Our results provide evidence that this kind of exercise produces a highly significant increase in plasma levels of the hormones involved in electrolyte and water balance. They also indicate that it is among the well-trained subjects that sweat loss is highest though the hematocrit increase is the smallest; this suggests that water is shifted more efficiently from the extravascular compartment.

Adult↗
PubMed1987

Effects of two high-intensity intermittent training programs interspaced by detraining on human skeletal muscle and performance.

The purpose of this study was to investigate the effects of repeated high-intensity intermittent training programs interspaced by detraining on human skeletal muscle and performances. First, nineteen subjects were submitted to a 15-week cycle ergometer training program which involved both continuous and high-intensity interval work patterns. Among these 19 subjects, six participated in a second 15-week training program after 7 weeks of detraining. Subjects were tested before and after each training program for maximal aerobic power and maximal short-term ergocycle performances of 10 and 90s. Muscle biopsy from the vastus lateralis before and after both training programs served for the determination of creatine kinase (CK), hexokinase, phosphofructokinase (PFK), lactate dehydrogenase (LDH), malate dehydrogenase, 3-hydroxyacyl-CoA dehydrogenase (HADH) and oxoglutarate dehydrogenase (OGDH) activities. The first training program induced significant increases in all performances and enzyme activities but not in CK. Seven weeks of detraining provoked significant decreases in maximal aerobic power and maximal 90s ergocycle performance. While the interruption of training had no effect on glycolytic enzyme markers (PFK and LDH), oxidative enzyme activities (HADH and OGDH) declined. These results suggest that a fairly long interruption in training has negligeable effects on glycolytic enzymes while a persistent training stimulus is required to maintain high oxidative enzyme levels in human skeletal muscle. The degree of adaptation observed after the second training program confirms that the magnitude of the adaptive response to exercise-training is limited.

Adult↗
PubMed1991

Dehydrogenase activation by Ca2+ in cells and tissues.

The activation of intramitochondrial dehydrogenases by Ca2+ provides a link between the intensity of work performance by a tissue and the activity of pyruvate dehydrogenase and the tricarboxylate cycle, and hence the rate of ATP production by the mitochondria. Several aspects of this model of the control of oxidative phosphorylation are examined in this article, with particular emphasis on mitochondrial functioning in situ in cardiac myocytes and in the intact heart. Recent use of the fluorescent Ca2+ chelating agents indo-1 and fura-2 has allowed a more quantitative description of the dependence of dehydrogenase activity upon concentration of free intramitochondrial Ca2+, in experiments with isolated mitochondria. Further, a novel technique developed by Miyata et al. has allowed description of free intramitochondrial Ca2+ within a single cardiac myocyte, and the conclusion that this parameter changes in response to electrical excitation of the cell over a range which would be expected to give substantial modulation of dehydrogenase activity.

Animals↗
PubMed1981

[Vitamin D 1980--a stocktaking (author's transl)].

Vitamin D3 and its various metabolites have a central position in the regulation of the calcium- and phosphorus metabolism. Of special importance is 1,25-dihydroxyvitamin D3, which is almost exclusively synthesized in the kidney. Its production is dependent upon several hormonal stimuli and of course occurs normally only in intact renal tissue. The multifactorial regulation of its formation implies that a variety of diseases could cause disturbances in the metabolism of vitamin D. 1,25-dihydroxyvitamin D3 exerts its biological effects not only at the intestine, bone and kidney, but as well presumably in organs as the parathyroid glands, hypophysis, pancreas and skin. 24,25-dihydroxyvitamin D3--although its biological value is still in debate--represents possibly a second vitamin D-hormone of importance. Inspite of intensive research work the metabolic fate of vitamin D3 and its full biological significance is not yet entirely understood.

24,25-Dihydroxyvitamin D 3↗
PubMed1986

Metabolic disorders in patients with calcium urolithiasis.

In the last two decades, intensive research work has been done in the field of urolithiasis. Due to improved and extended diagnostic methods, it has been recognized that metabolic disturbances play an important role in stone disease.

Acidosis, Renal Tubular↗
PubMed1990

Longterm meningeal involvement as the only clinical manifestation of low grade malignant non-Hodgkin's lymphoma.

We present the case of a 56-year-old man who developed-at the age of 46-paraesthesia and numbness in the perianal region, the feet and lower legs accompanied by the presence of B-lymphocytes in the cerebrospinal fluid (CSF). Despite intensive work-up an explanation was not found until he developed hepato-splenomegaly ten years after the initial symptoms. Haematologic evaluation at that time disclosed a low-grade malignant B-cell lymphoma. Repeated CSF examination revealed 31 leukocytes/mm3, of which were mainly lymphocytes. These proved to be B-lymphocytes of monoclonal origin. These findings suggest that a leptomeningeal localisation of a low-grade malignant lymphoma had been present for ten years before systemic manifestation of the disease.

Adult↗