Aerobic Stress Research Articles

Effect of Aerobic stress on responding some protein and cholesterol variables in blood serum

Effect of Aerobic stress on responding some protein and cholesterol variables in blood serum

Proteomic analysis of proteins expressed by Helicobacter pylori under oxidative stress

Helicobacter pylori is a spiral, slow growing gram-negative microaerophilic bacterium. It has been shown to be the etiological agent of gastroduodenal diseases, such as chronic gastritis, gastric and duodenal ulcers, and gastric cancer. To address the influence of oxidative stress and its underlying mechanisms, we have compared proliferation, urease activity and protein expression profile of H. pylori incubated under normal microaerophilic (5% O2) and aerobic stress (20% O2) conditions. Oxidative-stress cells displayed coccoid morphology and time-dependent decrease in proliferation. The urease activity was completely abrogated after 32 h. We have further compared the protein expression profiles of H. pylori under normal growing and oxidative-stress conditions by a global proteomic analysis, which includes high-resolution 2-DE followed by MALDI-TOF-MS and bioinformatic databases search/peptide-mass comparison. The results revealed that more than ten proteins were differentially expressed under oxidative stress. Most notably, the protein expression levels of urease accessory protein E (UreE, an essential metallochaperone for urease activity) and alkylhydroperoxide reductase (AhpC) with antioxidant potential are greatly decreased under stress conditions. Measurements of messenger RNA transcription level by performing RT-PCR on total mRNA also confirmed that gene expressions for these two proteins are consistently repressed under oxygen tension. These changes form a firm basis to account for the loss of urease activity and anti-oxidative ability of H. pylori after long-term exposure to reactive oxygen. Conceivably, UreE and AhpC may thus be listed as potential targets for the development of therapeutic drugs against H. pylori.

Relative Ef. cacy of Aerobic Training and Stress Management In Lowering Cardiovascular Activity During Psychological Stress

Relative Ef. cacy of Aerobic Training and Stress Management In Lowering Cardiovascular Activity During Psychological Stress

Allozyme Loci Selection in the Pacific Mussel Mytilus trossulus under Stressful Conditions

The allozyme variability for 15 loci in two samples of the Pacific mussel Mytilus trossulus collected from a single giant cluster was investigated using the method of gel electrophoresis. One sample was subjected to short-term anaerobic stress and then to a longer aerobic stress, leading to the death of about 85% of the individuals. At some of the loci, significant differences in the genotypic and allele frequencies were found between the samples. The results are suggestive of the differential survival of mussels with different genotypes and alleles at some of the surveyed loci under stress. Our data are in agreement with the hypothesis of the adaptive significance of allozyme polymorphism.

Effects of Anaerobic Preculture on Aerobic Stress Responses of Campylobacter jejuni

Survival responses to aerobic stress in the Campylobacterjejuni are highly influenced by preculturing conditions in either microaerobic or anaerobic environments before the stress is induced. In anaerobically precultured cells, culturability was maintained longer than that in microaerobically precultured cells under aerobic conditions, without significant concomitant damage to cellular components by aerobic stress, although the culturability finally fell below the level of detection. These results suggest a possibility that the survival of C. jejuni in natural aerobic environments is highly influenced by the environmental conditions, such as varied oxygen partial pressure, where the bacterium has resided.

Naive and Memory T Cell Subsets are Differentially Mobilized During Physical Stress

This study examined the naive and memory phenotypic profiles of CD4+ and CD8hi T cells that were mobilized to the peripheral circulation during a combination of aerobic exercise and heat stress, determining expression of the adhesion molecules CD62L and CD11a on the recruited cells. Twelve recreationally active males (age 27.1 +/- 5.3 yr, height 1.77 +/- 0.08 m, mass 76.9 +/- 12.0 kg, VO2peak 43.9 +/- 6.7 mL x kg(-1) x min(-1)) completed a 40 min bout of cycle ergometry at 65 % of VO2peak while immersed to mid-chest in a water bath at 39 degrees C. Venous blood samples were collected before (T0), during (T40) and 30 min after (T70) exposure to combined exercise and heat stress. Specimens were analyzed by three-colour flow cytometry for CD4+ and CD8hi T cell expression of CD45RO, CD11a and CD62L. Some 80 % of the CD4+ T cells that were mobilized were of the CD45RO memory phenotype, with the numbers of CD11alo and CD62L+ cells increasing more than those of CD11ahi and CD62L- cells. For the CD8hi cells, there was a more equal recruitment of CD45RO- naive (43 %) and CD45RO+ memory (57 %) cells. The majority (84 %) of recruited CD8+ cells were CD11ahi; there was a trend to predominance of CD62L- cells (57 %) for the memory subset, but with almost equal recruitment of CD62L+/- for the naive subset. We conclude that the exercise + heat stress induced trend to an increase in CD4+ T cells is linked in some way to memory phenotype; it cannot be explained simply by a high density expression of CD11a and lack of the lymph node homing receptor (CD62L). Furthermore, although mobilization of CD8hi T cells is not linked to memory phenotype, a high density expression of CD11a and a lack of the lymph node homing receptor are important determinants of CD8hi T cell mobilization.

An iron-regulated alkyl hydroperoxide reductase (AhpC) confers aerotolerance and oxidative stress resistance to the microaerophilic pathogen Campylobacter jejuni.

Microaerophiles like Campylobacter jejuni must resist oxidative stresses during transmission or infection. Growth of C. jejuni 81116 under iron limitation greatly increased the expression of two polypeptides of 26 and 55 kDa. The identification of these proteins by N-terminal amino acid sequencing showed both to be involved in the defense against oxidative stress. The 55-kDa polypeptide was identical to C. jejuni catalase (KatA), whereas the N terminus of the 26-kDa polypeptide was homologous to a 26-kDa Helicobacter pylori protein. The gene encoding the C. jejuni 26-kDa protein was cloned, and the encoded protein showed significant homology to the small subunit of alkyl hydroperoxide reductase (AhpC). The upstream region of ahpC encoded a divergent ferredoxin (fdxA) homolog, whereas downstream sequences contained flhB and motB homologs, which are involved in flagellar motility. There was no evidence for an adjacent homolog of ahpF, encoding the large subunit of alkyl hydroperoxide reductase. Reporter gene studies showed that iron regulation of ahpC and katA is achieved at the transcriptional level. Insertional mutagenesis of the ahpC gene resulted in an increased sensitivity to oxidative stresses caused by cumene hydroperoxide and exposure to atmospheric oxygen, while resistance to hydrogen peroxide was not affected. The C. jejuni AhpC protein is an important determinant of the ability of this microaerophilic pathogen to survive oxidative and aerobic stress.

A Novel High Activity Cationic Ascorbate Peroxidase from Tea ( Camellia sinensis) — A Class III Peroxidase with Unusual Substrate Specificity

A cationic class III peroxidase (TcAPX II) with the highest reported specific activity (kcat = 1,500 μmol min-1 mg-1) for ascorbate as reducing substrate has been isolated from freshly picked tea leaves (Camellia sinensis) in 45 % glycosylated, 55 % non-glycosylated forms. TcAPX II exhibits important structure-function differences with respect to not only conventional class I (e.g. pea cytosolic ascorbate peroxidase) and class III peroxidases (e.g. horseradish peroxidase) but also to another recently characterised class III ascorbate specific enzyme, TcAPX I [Kvaratskhelia et al. Plant Physiol. 144, 1237-1245 (1997)]. TcAPX II has a high preference for ascorbate as a reducing substrate, while TcAPX I oxidises ascorbate and organic phenols at 10-fold lower, but comparable rates. Hydrogen peroxide (100–4,000 fold excess) reacts with the ferric and compound II states of TcAPX II to yield compound II and an inactive type P670 species with no detectable compound III formation. The inactivation rate is comparable with that of horseradish peroxidase but significantly lower than that of pea cytosolic APX. These data together with the instability of TcAPX II compound I (t1/2 = 5 sec) in the absence of added reducing substrate, suggest that TcAPX II is protected from H2O2 induced inactivation by a catalase like reaction. Partial sequence data for TcAPX II show that recognised structural similarities between class I ascorbate peroxidases and yeast cytochrome c peroxidase (the archetypal class I peroxidase) are not essential for ascorbate peroxidase activity. TcAPX II is a distinct class III peroxidase of generic interest because of its potential to act as a key antioxidant in aerobic stress response in planta.

Coenzyme Q10 improves the tolerance of the senescent myocardium to aerobic and ischemic stress: studies in rats and in human atrial tissue.

The inferior recovery of cardiac function after interventional cardiac procedures in elderly patients compared to younger patients suggests that the aged myocardium is more sensitive to stress. We report two studies that demonstrate an age-related deficit in myocardial performance after aerobic and ischemic stress and the capacity of CoQ10 treatment to correct age-specific diminished recovery of function. In Study 1 the functional recovery of young (4 mo) and senescent (35 mo) isolated working rat hearts after aerobic stress produced by rapid electrical pacing was examined. After pacing, the senescent hearts, compared to young, showed reduced recovery of pre-stress work performance. CoQ10 pretreatment (daily intraperitoneal injections of 4 mg/kg CoQ10 for 6 weeks) in senescent hearts improved their recovery to match that of young hearts. Study 2 tested whether the capacity of human atrial trabeculae (obtained during surgery) to recover contractile function, following ischemic stress in vitro (60 min), is decreased with age and whether this decrease can be reversed by CoQ10. Trabeculae from older individuals (> or = 70 yr) showed reduced recovery of developed force after simulated ischemia compared to younger counterparts (< 70 yr). Notably, this age-associated effect was prevented in trabeculae pretreated in vitro (30 min at 24 degrees C) with CoQ10 (400 MicroM). We measured significantly lower CoQ10 content in trabeculae from > or = 70 yr patients. In vitro pretreatment raised trabecular CoQ10 content to similar levels in all groups. We conclude that, compared to younger counterparts, the senescent myocardium of rats and humans has a reduced capacity to tolerate ischemic or aerobic stress and recover pre-stress contractile performance, however, this reduction is attenuated by CoQ10 pretreatment.

Coenzyme Q10 Treatment Improves the Tolerance of the Senescent Myocardium to Pacing Stress in the Rat

In elderly patients the results of cardiac interventions are inferior to those in the young. A possible contributing factor is an age-related reduction in cellular energy transduction during the intervention which may induce aerobic or ischemic stress. To investigate whether coenzyme Q10 (CoQ10) improves the response to aerobic stress, functional recoveries of senescent and young rat hearts after rapid pacing were compared with or without CoQ10.Young (4.8 +/- 0.1 months) and senescent (35.3 +/- 0.2 months) rats were given daily intraperitoneal injections of CoQ10 (4 mg/kg) or vehicle for 6 weeks. Their isolated hearts were rapidly paced at 510 beats per minute for 120 min to induce aerobic stress without ischemia.In senescent hearts pre-pacing cardiac work was 74% and oxygen consumption (MVO2) 66% of that in young hearts. CoQ10 treatment abolished these differences. After pacing, the untreated senescent hearts, compared to young, showed reduced recovery of pre-pacing work, (16.8 +/- 4.3 vs. 44.5 +/- 7.4%; P < 0.01). CoQ10 treatment in senescent hearts improved recovery of work, (48.1 +/- 4.1 vs. 16.8 +/- 4.3%; P < 0.0001) and MVO2 (82.1 +/- 2.8 vs. 61.3 +/- 4.0%; P < 0.01) in treated versus untreated hearts respectively. Post-pacing levels of these parameters in CoQ10 treated senescent hearts were as high as in young hearts.(1) Senescent rat hearts have reduced baseline function and reduced tolerance to aerobic stress compared to young hearts. (2) Pre-treatment with CoQ10 improves baseline function of the senescent myocardium and its tolerance to aerobic stress.

Psychological Functioning Among Middle-Aged and Older Adult Pulmonary Patients in Exercise Rehabilitation

Twenty-seven adults (10 men, 17 women) with chronic pulmonary disease participated in a 30-day rehabilitation program including aerobic exercise, education, and stress management. Mean age of the sample was 55.5± 15.8 years (Range:27-83 years). Subjects underwent assessments of physiological functioning, neuropsychological functioning, and psychological well-being before (Time 1) and after (Time 2) the exercise program. Using a median age split, the sample was divided into older adult (mean age-68.6± 9.2) and middle-aged (mean age= 43.4 ± 9.5) groups, and data were analyzed by multivariate analysis of variance, with age as a between subjects factor. The exercise intervention has no significant effect on indicators of pulmonary function, but both age groups achieved significant gains in cardiopulmonary endurance. Middle-aged subjects functioned at a higher level than older adult subjects at both times of measurement, and middle-aged subjects achieved significantly greater gains in walking distance than old...

Longer lifting hooks for forestry workers: An evaluation of ergonomic effects

This study analysed the load-reducing effects of using lifting hooks that were 0.09 m longer than those conventionally employed by forestry workers. A method for recording and analysing repetitive lifting movements is also presented. Nine experienced workers performed a standardized sagittal symmetric repetitive lifting task, with the Long and the Standard types of hook. To simulate the aerobic stress during motor-manual cutting, a 17-kg log was lifted 15 lifts·min −1. Heart rate, oxygen consumption, sagittal body movements, vertical force plate measurements, and vertical movement of the log lifted, were recorded continuously. Sagittal load moments and forces in hip and L5-S1 segment were calculated. The subjects also rated their overall, low-back and thigh exertions. The use of the Long hook resulted in a 12% reduction in O 2 consumption. Mean and peak load moments in hip and L5-S1 were reduced by 14% and 9% respectively. The loads were rated significantly lower with all three assessments. The movement analyses showed a significant difference in movement pattern between the two types of hook, and that the kinematic variables were related to each other and to the VO 2 measurements in a consistent way.

Age-dependent effect of resistance exercise on growth hormone secretion in people.

We measured serum GH responses to a standardized circuit of resistance exercise in 12 young subjects (6 men and 6 women; 27 +/- 1.6 yr old) and in 11 elders (6 men and 5 women; 72 +/- 0.8 yr old). Initial assessment of strength [1 repetition maximum (1RM)] was made of 12 muscle groups using Nautilus equipment. One week later, subjects carried out the exercise protocol, 3 sets of 8 repetitions for each of the 12 exercises, at 70% of predetermined 1RM values. Venous blood was drawn at baseline, after each exercise, and every 2 min during 10 min of recovery. In young subjects serum immunoreactive GH rose by completion of the second exercise, increased and remained elevated through the remainder of the exercise period, and decreased toward baseline by 10 min of recovery. In the elderly subjects, baseline GH values were similar to those in the young (1.76 +/- 0.41 vs. 2.61 +/- 0.73 micrograms/L) and did not increase above 6 micrograms/L at any time during or after exercise. Exercise increased GH in both groups, but peak values (14.9 +/- 3.5 micrograms/L in young; 2.44 +/- 0.6 micrograms/L in old) and integrated (198 +/- 47 in young; 37.8 +/- 0.8 in old) were significantly greater in the young subjects (P less than 0.05). GH responses showed no gender difference in either group. Brief increases in pulse rate were observed during individual exercises, but sustained elevations did not occur. To assess the effect of exercise intensity on GH response, we compared responses to exercise at 70% and 85% of 1RM in 7 young and 11 older people. In the young subjects, GH responses were nonsignificant at 60% and increased progressively at 70% and 85% of 1RM. No significant effect of exercise intensity was observed in the older subjects. We conclude that resistance exercise promptly elevates circulating GH concentrations in healthy young adults. This response is related to the intensity of the resistance stimulus, although a small contribution of aerobic stress cannot be excluded. The GH response to resistance activity is grossly diminished in healthy elderly men and women.

Growth and motor performance of healthy Senegalese preschool children.

Body dimensions, motor performance tests, and an aerobic stress test were measured on three different occasions on a group of 88 healthy Senegalese children, 3-6 years of age. The children were divided into 3 cohorts according to year of birth: 1985, 1984, and 1983. The children displayed linear growth approaching North American reference data but had significant weight deficits. Their growth, however, proceeded favorably compared to Senegalese children of the previous generation. In the group of children born in 1983, boys were more muscular and had less arm fat than girls. Motor performances of Senegalese children were inferior to those of European children, but after normalization by body mass, differences in jumping and throwing tasks tended to diminish. Stepwise regression showed that variations in motor performances were particularly due to age, body weight, and stature. The importance of nutritional factors is stressed to explain the development of performance and cardiorespiratory fitness of these children. © 1992 Wiley-Liss, Inc.

Stress reactivity and exercise training in premenopausal and postmenopausal women.

Examined the influence of ovarian function on psychophysiological stress responses and determined if aerobic exercise reduced stress reactivity. Fifty premenopausal and postmenopausal women initially were subjected to a public speaking task and an ice-on-the-forehead procedure, during which time their blood pressure and heart rate were monitored and continuous blood samples were obtained. Subjects also underwent aerobic fitness evaluations with a maximum-exercise treadmill test. Subjects were then randomly assigned to a 12-week exercise program of either aerobic exercise (e.g., walking and jogging at a prescribed exercise intensity) or non-aerobic strength and flexibility training and were then reevaluated. Results indicated that postmenopausal women exhibited lower resting epinephrine levels but greater epinephrine reactivity to the speaking task compared to the premenopausal women. There were no differences between premenopausal and postmenopausal women with respect to cardiovascular or catecholamine responses during the cold challenge. Premenopausal and postmenopausal women also achieved comparable improvements in aerobic fitness. However, results of the mental stress testing were complex and provided only partial support for the role of aerobic exercise in reducing stress responses.

Influence of acute maximal exercise on lecithin: cholesterol acyltransferase activity in healthy adults of differing aerobic performance

To document the possible influence of a single episode of maximal aerobic stress on the serum lecithin:cholesterol acyltransferase (LCAT) activity in subjects with differing histories of training, two groups of healthy male adults [controls (C), n = 18, 28.6 years, SD 5.2, 50.1 ml.kg-1.min-1 maximal O2 uptake (VO2max), SD 5.3; endurance trained athletes (T), n = 18, 31.4 years, SD 8.8, 65.0 ml.kg-1.min-1 VO2max, SD 2.8] were examined in a maximal aerobic stress test. In addition to the routine assessment of lipid status, LCAT activity was measured immediately before and after exercise. At rest nearly identical LCAT activity values were found in both groups: C 64.4 nmol.ml-1.h-1, SD 16.7 vs T 65.0 nmol.ml-1.h-1, SD 20.9. The post-exercise LCAT values induced by the maximal stress test increased significantly to (C) 95.7 nmol.ml-1.h-1, SD 23.5, +48.6%, P less than 0.001; (T) 83.5 nmol.ml-1.h-1, SD 24.3, +29.1%, P less than 0.01. Neither the pre nor the postexercise individual LCAT activity values showed any significant correlation to the corresponding data on physical performance.

Exercise-induced arrhythmias in diuretic-treated patients with uncomplicated systemic hypertension

Although hypertensioe patients have been shown to have a higher prevalence of arrhythmias during ambulatory monitoring when treated with diuretic drugs than when untreated, the effects of maximal aerobic stress on arrhythmia frequency in such patients is unknown. The incidence of arrhythmias during graded maximal treadmill exercise in a group of 68 subjects with mild, clinically uncomplicated systemic hypertension treated chronically with diuretics alone for a median of 4.5 years was compared with that in an age-matched normotensive control group. The prevalence of exercise-induced arrhythmias was higher in the group treated with diuretics, than in the control group, 57% vs 38% (p <0.05) This difference was entirely due to the higher incidence of isolated atrial or ventricular premature complexes in the diuretic-treated patients, 44% vs 26% (p <0.05). There was no difference in the incidence of frequent (more than 10% of beats) or complex supraventricular or ventricular premature complexes between the diuretic-treated and control groups. Within the diuretic group, no difference in the incidence of simple or complex arrhythmia was found between men and women, between those with and those without rest or exercise-induced electrocardiographic abnormalities or between those with a serum potassium level of less than 3.7 mEq/liter vs those with a level of 3.7 mEq/liter or greater. Thus, patients with uncomplicated hypertension treated with chronic diuretic monotherapy do not appear to be at increased risk for major arrhythmias during aerobic exercise.

Stress-management interventions: A 15-month follow-up of aerobic conditioning and stress inoculation training

This report presents findings from a 15-month follow-up of a study that compared the effectiveness of aerobic conditioning (i.e., jogging) and stress inoculation training in the reduction of anxiety for chronically stressed community residents (N =61). At this follow-up, both interventions led to continued reports of significantly less anxiety and greater self-efficacy. The superior treatment effects of stress inoculation in modifying inner dialogue, increasing positive self-statements, and decreasing negative self-statements were maintained. In addition, subjects experiencing stress predominantly as cognitive anxiety either maintained or increased their anxiety from post to follow-up, while somatic subjects continued to reduce their anxiety level. This held regardless of treatment condition. Since only 40% of the jogging group were still jogging at follow-up, the long-term maintenance of therapeutic gain with aerobic conditioning warrants further investigation.

Prediction of maximal aerobic power in man.

A general prediction formula has been derived for predicting maximal aerobic power (VO2 max) based on nonlinear relationship between aerobic stress and cardiorespiratory strains imposed on the subject during submaximal exercise on bicycle ergometer. The validity of the prediction formula has been tested for the data consisting of 135 observations on 45 moderately active young subjects who were asked to exercise on the bicycle ergometer at three submaximal and one maximal work rate. It has been found that product moment correlations of aerobic stress with respiratory strain and cardiac strain expressed logarithmically were 0.7651 and 0.7457 respectively. These correlations were significant (P less than 0.001). The multiple correlation between observed and estimated aerobic stress expressed logarithmically in terms of cardiorespiratory strains was 0.8142 which was significant (P less than 0.001). There is a significant improvement in multiple correlation from the product moment correlations of aerobic stress with either of two strains expressed logarithmically. It has been conclusively established that combined index of cardioresiratory strains will be better predictor of aerobic stress than either respiratory or cardiac strain alone as commonly employed by several workers.

Stress relaxation of unaccelerated natural rubber–sulfur vulcanizates before and after treatment with triphenylphosphine

AbstractThe aerobic and anaerobic stress relaxation of unaccelerated natural rubber–sulfur vulcanizate networks has been examined before and after treatment with triphenylphosphine, a reagent which converts polysulfidic crosslinks into di‐ and monosulfide crosslinks. This treatment reduces the rate of anaerobic stress relaxation and makes the network more susceptible to protection by zinc dibutyldithiocarbamate against aerobic stress relaxation. Aerobic stress relaxation of the network after treatment with triphenylphosphine remains nonautocatalytic, indicating that it still contains the precursor of an antioxidant, and crosslinking continues to occur during aging, showing that the presence of polysulfide groups is not a sole prerequisite for such network formation.