Longitudinal changes in physical capacity from adolescence to middle age in men and women

The aim was to investigate how physical capacity changes from adolescence through early adulthood to middle age with focus on early aging. The aim was also to study if physical capacity in middle age could be predicted by factors in adolescence or early adulthood. A cohort of men and women in Sweden (SPAF-1958, n = 425) have been followed for 36 years, at 16, 34, and 52 years of age. The study includes, among other variables, objective measures of physical capacity. At age 52, 50% of the original cohort participated in exercise testing. Physical capacity increased from 16 to 34 years. From 34 to 52 years, physical capacity decreased in both genders by 15-20% in all but one test. Physical capacity at 16 and 34 years of age were better predictors of physical capacity at age 52 than body dimensions, school grades and life style factors. In conclusion, present data confirm earlier cross-sectional studies regarding the decrease in aerobic capacity and muscular strength during the early ageing period in both genders. The study has also generated novel data that show a smaller decline in muscular endurance than previously reported. Finally, physical capacity is fairly stable from adolescence to middle age.

Custom-Shaped Organic Photovoltaic Modules-Freedom of Design by Printing

Freedom of design that was introduced as organic photovoltaic (OPV) modules were fabricated by printing. As proof-of-concept, we show OPV leaf fabrication in A5 size using gravure and rotary screen printing processes for the main active layers of the OPV structure. These printing methods allow direct printing of any kind of arbitrary, two-dimensional shapes including patterning of the electric contacts thus post-patterning stages are not needed. Fabrication of custom-shaped OPV modules requires detailed information about the technical boundaries set by the manufacturing process and materials which in turn influence the layout design and R2R upscaling. In this paper, we show custom-shaped OPV modules, patterned directly in a shape of a tree leaf with an overall size of 110 cm² and an active area of 50 cm² providing a power conversion efficiency of 2.0% and maximum power of 98 mW.

Influence of pericardial suction blood retransfusion on memory function and release of protein S100B

Background: To study the influence of pericardial suction blood (PSB) on postoperative memory disturbances and release patterns of protein S100B during and after cardiopulmonary bypass (CPB).

Methods: Sixty male patients admitted for coronary artery bypass surgery were prospectively randomized to receive PSB either by using conventional cardiotomy suction retransfusion or after cell-saver processing.

Results: The concentration of S100B rose during the period of CPB from 0.065±0.004 to 0.24±0.001 mg/L (p<0.001). PSB contained 18.0±1.7 mg/L of S100B. Direct retransfusion from the cardiotomy reservoir made the systemic level increase to 1.42±0.19 mg/L compared to 0.25±0.02 mg/L using a cell-saver. Signs of postoperative memory dysfunction (> 1 SD) were discovered in one of three tests, but were unrelated to technique of retransfusion. No associations were found between serum concentrations of S100B and memory function.

Conclusion: In this study, retransfusion of PSB during cardiac surgery appeared not to cause memory disturbances. PSB contained high concentrations of protein S100B making its use as a marker of cerebral injury unsuitable.

Metapopulation effective size and conservation genetic goals for the Fennoscandian wolf (Canis lupus) population

The Scandinavian wolf population descends from only five individuals, is isolated, highly inbred and exhibits inbreeding depression. To meet international conservation goals, suggestions include managing subdivided wolf populations over Fennoscandia as a metapopulation; a genetically effective population size of N_e⩾500, in line with the widely accepted long-term genetic viability target, might be attainable with gene flow among subpopulations of Scandinavia, Finland and Russian parts of Fennoscandia. Analytical means for modeling N_e of subdivided populations under such non-idealized situations have been missing, but we recently developed new mathematical methods for exploring inbreeding dynamics and effective population size of complex metapopulations. We apply this theory to the Fennoscandian wolves using empirical estimates of demographic parameters. We suggest that the long-term conservation genetic target for metapopulations should imply that inbreeding rates in the total system and in the separate subpopulations should not exceed Δf=0.001. This implies a meta-Ne of N_eMeta⩾500 and a realized effective size of each subpopulation of N_eRx⩾500. With current local effective population sizes and one migrant per generation, as recommended by management guidelines, the meta-N_e that can be reached is ~250. Unidirectional gene flow from Finland to Scandinavia reduces meta-N_e to ~130. Our results indicate that both local subpopulation effective sizes and migration among subpopulations must increase substantially from current levels to meet the conservation target. Alternatively, immigration from a large (N_e⩾500) population in northwestern Russia could support the Fennoscandian metapopulation, but immigration must be substantial (5–10 effective immigrants per generation) and migration among Fennoscandian subpopulations must nevertheless increase.

Effects of a one-year physical activity programme for women with systemic lupus erythematosus - a randomized controlled study

OBJECTIVES

To study the effects of a one-year physical activity programme on aerobic capacity, physical activity and health-related quality of life (HRQL) in patients with systemic lupus erythematosus (SLE) by a randomized control design.

METHODS

Thirty-five women with low or moderate disease activity and organ damage were randomized to intervention (I) or control (C) group. The intervention during months 0-3 consisted of education, supervised aerobic exercise at high intensity and individual coaching, as well as self-managed physical activity at low-to-moderate intensity. During months 4-12, the physical activity was self-managed and the coaching was successively reduced over time. Outcome measures included: maximal oxygen uptake (VO2 max) from a bicycle ergometer test, self-reported physical activity and HRQL (SF-36).

RESULTS

VO2 at sub-max. and max. increased, independent of group, during the one-year study period (main effect of time p < 0.0001). VO2 max. increased between baseline and month 3 (p < 0.0001), between months 3 and 6 (p = 0.01) and the increase was sustained at month 12 (ns). Frequency of physical activity at high intensity also increased, independent of group, during the study period. It was increased at months 3, 6 and 12 compared to baseline (p = 0.02, p < 0.001, p = 0.03). Improvement in mental health between baseline and month 6 (p = 0.002) was seen for the I-group, not the C-group (p = 0.03). Disease activity and organ damage did not change.

CONCLUSIONS

Physical activity and aerobic capacity increased after supervised exercise and coaching, and the improvement was sustained during the one-year programme. However, no interactions between the group differences were seen, which suggests that repeated measurements could motivate to increased physical activity and thereby to increased aerobic capacity. As sub-max. VO2 increased over time, training-induced changes in VO2 on-kinetics could be another explanation. Little influence on HRQL was seen after the programme. The study indicates that physical activity at high intensity over one year is tolerated by patients with mild to moderate SLE.

R2R-printed inverted OPV modules--towards arbitrary patterned designs

We describe the fabrication of roll-to-roll (R2R) printed organic photovoltaic (OPV) modules using gravure printing and rotary screen-printing processes. These two-dimensional printing techniques are differentiating factors from coated OPVs enabling the direct patterning of arbitrarily shaped and sized features into visual shapes and, increasing the freedom to connect the cells in modules. The inverted OPV structures comprise five layers that are either printed or patterned in an R2R printing process. We examined the rheological properties of the inks used and their relationship with the printability, the compatibility between the processed inks, and the morphology of the R2R-printed layers. We also evaluate the dimensional accuracy of the printed pattern, which is an important consideration in designing arbitrarily-shaped OPV structures. The photoactive layer and top electrode exhibited excellent cross-dimensional accuracy corresponding to the designed width. The transparent electron transport layer extended 300 µm beyond the designed values, whereas the hole transport layer shrank 100 µm. We also examined the repeatability of the R2R fabrication process when the active area of the module varied from 32.2 cm(2) to 96.5 cm(2). A thorough layer-by-layer optimization of the R2R printing processes resulted in realization of R2R-printed 96.5 cm(2) sized modules with a maximum power conversion efficiency of 2.1% (mean 1.8%) processed with high functionality.

Sprint exercise enhances skeletal muscle p70S6k phosphorylation and more so in women than in men

AIM

Sprint exercise is characterized by repeated sessions of brief intermittent exercise at a high relative workload. However, little is known about the effect on mTOR pathway, an important link in the regulation of muscle protein synthesis. An earlier training study showed a greater increase in muscle fibre cross-sectional area in women than men. Therefore, we tested the hypothesis that the activation of mTOR signalling is more pronounced in women than in men. Healthy men (n=9) and women (n=8) performed three bouts of 30-s sprint exercise with 20-min rest in between.

METHODS

Multiple blood samples were collected over time, and muscle biopsy specimens were obtained at rest and 140 min after the last sprint.

RESULTS

Serum insulin increased by sprint exercise and more so in women than in men [gender (g) × time (t)]: P=0.04. In skeletal muscle, phosphorylation of Akt increased by 50% (t, P=0.001) and mTOR by 120% (t, P=0.002) independent of gender. The elevation in p70S6k phosphorylation was larger in women (g × t, P=0.03) and averaged 230% (P=0.006) as compared to 60% in men (P=0.04). Phosphorylation rpS6 increased by 660% over time independent of gender (t, P=0.003). Increase in the phosphorylation of p70S6k was directly related to increase in serum insulin (r=0.68, P=0.004).

CONCLUSION

It is concluded that repeated 30-s all-out bouts of sprint exercise separated by 20 min of rest increases Akt/mTOR signalling in skeletal muscle. Secondly, signalling downstream of mTOR was stronger in women than in men after sprint exercise indicated by the increased phosphorylation of p70S6k.

Training response of mitochondrial transcription factors in human skeletal muscle

AIM

Mitochondrial function is essential for physical performance and health. Aerobic fitness is positively associated with mitochondrial (mt) biogenesis in muscle cells through partly unknown regulatory mechanisms. The present study aimed to investigate the influence of exercise and training status on key mt transcription factors in relation to oxidative capacity in human skeletal muscle.

METHODS

The basal mRNA and protein levels of mitochondrial transcription factor A (TFAM), mitochondrial transcription factors B1 (TFB1M) or B2 (TFB2M), and mRNA levels of mitochondrial transcription termination factor (mTERF), were measured in a cross-sectional study with elite athletes (EA) and moderately active (MA) and the basal mRNA levels of these factors were measured during a 10-day endurance training programme with (R-leg) and without (NR-leg) restricted blood flow to the working leg.

RESULTS

TFAM protein expression was significantly higher in the EA than in the MA, while protein levels of TFB1M and TFB2M were not different between the groups. There was no difference between EA and MA, or any effect with training on TFAM mRNA levels. However, the mRNA levels of TFB1M, TFB2M and mTERF were higher in EA compared with MA. For TFB1M and TFB2M, the mRNA expression was increased in the R-leg after 10 days of training, but not in the NR-leg. mTERF mRNA levels were higher in EA compared with MA.

CONCLUSION

This study further establishes that TFAM protein levels are higher in conditions with enhanced oxidative capacity. The mRNA levels of TFB1M and TFB2M are influenced by endurance training, possibly suggesting a role for these factors in the regulation of exercise-induced mitochondrial biogenesis.

Greater growth hormone and insulin response in women than in men during repeated bouts of sprint exercise

AIM

In a previous study, sprint training has been shown to increase muscle cross-sectional area in women but not in men [Eur J Appl Physiol Occup Physiol 74 (1996) 375]. We hypothesized that sprint exercise induces a different hormonal response in women than in men. Such a difference may contribute to explaining the observed gender difference in training response.

METHOD

Metabolic and hormonal response to three 30-s sprints with 20-min rest between the sprints was studied in 18 physically active men and women.

RESULTS

Accumulation of blood lactate [interaction term gender (g) x time (t): P = 0.022], and plasma ammonia (g x t: P < 0.001) after sprint exercise was greater in men. Serum insulin increased after sprint exercise more so in women than in men (g x t: P = 0.020), while plasma glucose increased in men, but not in women (g x t: P < 0.001). Serum growth hormone (GH) increased in both women and men reaching similar peak levels, but with different time courses. In women the peak serum GH level was observed after sprint 1, whereas in men the peak was observed after sprint 3 (g x t; P < 0.001). Serum testosterone tended to decrease in men and increase in women (g x t: P = 0.065). Serum cortisol increased approx. 10-15% after sprint exercise, independent of gender (time: P = 0.005).

CONCLUSION

Women elicited a greater response of serum GH and insulin to sprint exercise. This may contribute to explaining the earlier observed muscle hypertrophy in women in response to sprint training.

Activation of estrogen response elements is mediated both via estrogen and muscle contractions in rat skeletal muscle myotubes

The aim of the present study was to investigate the activation of estrogen response elements (EREs) by estrogen and muscle contractions in rat myotubes in culture and to assess whether the activation is dependent on the estrogen receptors (ERs). In addition, the effect of estrogen and contraction on the mRNA levels of ERalpha and ERbeta was studied to determine the functional consequence of the transactivation. Myoblasts were isolated from rat skeletal muscle and transfected with a vector consisting of sequences of EREs coupled to the gene for luciferase. The transfected myoblasts were then differentiated into myotubes and subjected to either estrogen or electrical stimulation. Activation of the ERE sequence was determined by measurement of luciferase activity. The results show that both ERalpha and ERbeta are expressed in myotubes from rats. Both estrogen stimulation and muscle contraction increased (P < 0.05) transactivation of the ERE sequence and enhanced ERbeta mRNA, whereas ERalpha was unaffected by estrogen and attenuated (P < 0.05) by muscle contraction. Use of ER antagonists showed that, whereas the estrogen-induced transactivation is mediated via ERs, the effect of muscle contraction is ER independent. The muscle contraction-induced transactivation of ERE and increase in ERbeta mRNA were instead found to be MAP kinase (MAPK) dependent. This study demonstrates for the first time that muscle contractions have a similar functional effect as estrogen in skeletal muscle myotubes, causing ERE activation and an enhancement in ERbeta mRNA. However, in contrast to estrogen, the effect is independent of ERs and dependent on MAPK, suggesting activation via the estrogen related receptor (ERR).

Diagnosis of bacterial kidney disease by detection of Renibacterium salmoninarum by real-time PCR

Bacterial kidney disease (BKD), caused by Renibacterium salmoninarum (Rs), is a serious threat to salmon in aquaculture as well as to wild populations. We have developed a real-time polymerase chain reaction (PCR) for detection of Rs in kidney samples. The PCR is based on detection of unique parts of the 16S rRNA gene of Rs and DNA equivalent to 1-10 Rs genomes was detected per reaction. No cross-reactivity with other fish pathogenic or related bacteria could be demonstrated. Analysis of individual kidney samples collected from BKD classified populations identified 39.9% of the fish as positive by real-time PCR compared with 28.0% by polyclonal enzyme-linked immunosorbent assay (ELISA). The real-time PCR assay was found to be well suited for complementary use with ELISA for diagnosis of BKD, with the ability to detect clinical as well as covert Rs infections. The infection level determined by the polyclonal ELISA and by real-time PCR was significantly correlated.

Aerobic capacity correlates to self-assessed physical function but not to overall disease activity or organ damage in women with systemic lupus erythematosus with low-to-moderate disease activity and organ damage

The present aim is to investigate the relationships between aerobic capacity and disease activity, organ damage, health-related quality of life (HRQL) and physical activity in 34 women with systemic lupus erythematosus (SLE) with low-to-moderate disease activity and organ damage. Mean age was 51 (SD 10) years, disease duration 17 (SD 11) years. Aerobic capacity (maximal oxygen uptake/VO2 max) was measured with a bicycle ergometer exercise test. Overall disease activity was assessed with Systemic Lupus Activity Measure (SLAM) and the modified Systemic Lupus Erythematosus-Disease Activity Index (modified SLE-DAI), overall organ damage with the Systemic Lupus International Collaboration Clinics/American College of Rheumatology-Damage Index, [SLICC/(ACR)-DI], HRQL with the 36-item Short-form health-survey (SF-36) and physical activity with a self-assessed question. The women who were low-to-moderately physically active had 89-92% (P < or = 0.001) of VO2 max predicted for sedentary women. Maximal oxygen uptake (L/min, mL/min/kg) correlated to SF-36 physical function (rs = 0.49, rs = 0.72) (P < or = 0.01), but not (rs < or = 0.25) to other HRQL scales, overall disease activity or organ damage or physical activity. The correlation between aerobic capacity and physical function and the absence of correlation between aerobic capacity and physical activity, suggest a possible disease-related factor behind the low aerobic capacity. However, with no correlation between aerobic capacity and overall disease activity and organ damage, low physical activity may contribute to the low aerobic capacity in our sample.

The influence of physical training on the angiopoietin and VEGF-A systems in human skeletal muscle

Eleven subjects performed one-legged exercise four times per week for 5 wk. The subjects exercised one leg for 45 min with restricted blood flow (R leg), followed by exercise with the other leg at the same absolute workload with unrestricted blood flow (UR leg). mRNA and protein expression were measured in biopsies from the vastus lateralis muscle obtained at rest before the training period, after 10 days, and after 5 wk of training, as well as 120 min after the first and last exercise bouts. Basal Ang-2 and Tie-1 mRNA levels increased in both legs with training. The Ang-2-to-Ang-1 ratio increased to a greater extent in the R leg. The changes in Ang-2 mRNA were followed by similar changes at the protein level. In the R leg, VEGF-A mRNA expression responded transiently after acute exercise both before and after the 5-wk training program. Over the course of the exercise program, there was a concurrent increase in basal VEGF-A protein and VEGFR-2 mRNA in the R leg. Ki-67 mRNA showed a greater increase in the R leg and the protein was localized to the endothelial cells. In summary, the increased translation of VEGF-A is suggested to be caused by the short mRNA burst induced by each exercise bout. The concurrent increase in the Ang-2-to-Ang-1 ratio and the VEGF-expression combined with the higher level of Ki-67 mRNA in the R leg indicate that changes in these systems are of importance also in nonpathological angiogenic condition such as voluntary exercise in humans. It further establish that hypoxia/ischemia-related metabolic perturbation is likely to be involved as stimuli in this process in human skeletal muscle.

A single bout of exercise activates matrix metalloproteinase in human skeletal muscle

The aims of this study were 1) to characterize changes in matrix metalloproteinase (MMP), endostatin, and vascular endothelial growth factor (VEGF)-A expression in skeletal muscle in response to a single bout of exercise in humans; and 2) to determine if any exchange of endostatin and VEGF-A between circulation and the exercising leg is associated with a change in the tissue expression or plasma concentration of these factors. Ten healthy males performed 65 min of cycle exercise, and muscle biopsies were obtained from the vastus lateralis muscle at rest and immediately and 120 min after exercise. In the muscle biopsies, measurements of mRNA expression levels of MMP-2, MMP-9, MMP-14, and tissue inhibitor of metalloproteinase; VEGF and endostatin protein levels; and MMP activities were performed. Femoral arterial and venous concentrations of VEGF-A and endostatin were determined before, during, and 120 min after exercise. A single bout of exercise increased MMP-9 mRNA and activated MMP-9 protein in skeletal muscle. No measurable increase of endostatin was observed in the skeletal muscle or in plasma following exercise. A concurrent increase in skeletal muscle VEGF-A mRNA and protein levels was induced by exercise, with no signs of peripheral uptake from the circulation. However, a decrease in plasma VEGF-A concentration occurred following exercise. Thus 1) a single bout of exercise activated the MMP system without any resulting change in tissue endostatin protein levels, and 2) the increased VEGF-A protein levels are due to changes in the skeletal muscle tissue itself. Other mechanisms are responsible for the observed exercise-induced decrease in VEGF-A in plasma.

Qigong reduces stress in computer operators

Chinese research indicates that the Qigong method reduces psychosomatic and physical symptoms through an effect on the sympathetic nervous system.

OBJECTIVES

The aim was to investigate the effects of Qigong on stress among computer operators.

DESIGN

Ten women were included in a Qigong group and an equal number in a control group. Heart rate, blood pressure, and finger temperature were measured at the beginning and at the end of the working day during 5 weeks. twenty four-hours urine samples were collected in the first and last weeks to measure catecholamine excretion in urine. Participants kept a daily record of psychological measures of strain and weekly measures of stress levels.

RESULTS AND CONCLUSIONS

Qigong reduced noradrenaline excretion in urine (p<0.05), and influenced the heart rate and temperature, indicating reduced activity of the sympathetic nervous system. Moreover, Qigong reduced low-back symptoms (p<0.05). In conclusion, Qigong exercise may reduce stress at computerised work.

Human skeletal muscle fibre type variations correlate with PPAR alpha, PPAR delta and PGC-1 alpha mRNA

AIMS

Studies from genetically modified animals have been instrumental in highlighting genes and their products involved in the regulation of muscle fibre type and oxidative phenotypes; however, evidence in humans is limited. Our aim was therefore to investigate expression of those genes implicated in the regulation of oxidative fibre phenotypes in humans.

METHODS

Using quantitative polymerase chain reaction we determined mRNA expression of selected genes in skeletal muscle from three different groups, displaying physiological and pathological variations in muscle fibre type, activity and skeletal muscle metabolism respectively: (i) elite athletes (cyclists), with an increased proportion of type I slow twitch, oxidative fibres, (ii) normally active subjects with an average fibre type distribution, and (iii) spinal cord-injured subjects with a low proportion of type I fibres.

RESULTS

Skeletal muscle mRNA expression of calcineurin Aalpha and Abeta, peroxisome proliferator-activated receptor (PPAR)-alpha and -delta, and PPAR gamma coactivator (PGC)-1alpha and -1beta was determined. Calcineurin Aalpha and calcineurin Abeta mRNA expression was similar between groups. In contrast, mRNA expression of PPARalpha, PPARdelta, PGC-1alpha and -1beta was increased in athletes, when compared with normally active subjects. Furthermore, mRNA expression of PPARalpha, PPARdelta, PGC-1alpha and -1beta was reduced in spinal cord-injured subjects. Additionally, PPARalpha, PPARdelta and PGC-1alpha correlated with oxidative fibre content.

CONCLUSION

Skeletal muscle mRNA expression of PPARalpha, PPARdelta, PGC-1alpha and -1beta reflects differences in type I muscle fibres associated with pathologically and physiologically induced skeletal muscle fibre type differences.

Low physical activity among adolescents in practical education

The aim of this study was to investigate physical activity levels and factors related to physical activity among 16-year-old girls and boys in secondary school practical and theoretical programs. An additional aim was to identify factors contributing to differences in physical activity patterns between the educational programs. Sixteen-year-old students in the first year of secondary school in Sweden (n=585) were systematically selected and 93% agreed to complete a questionnaire. Compared with students in theoretical programs, those in practical programs spent less time and energy per day in physical activity. Girls in practical programs were the least physically active, and boys in theoretical programs the most physically active students. Statistical analysis showed that, among students in practical programs, the influence of educational program on physical activity level was explained by lower socio-economic level, less parental support, lower perceived health level, and negative attitudes toward outdoor physical activities. These data suggest that promotion of physical activity should focus on students, especially girls, in practical programs. Because the difference in physical activity levels between educational programs was partly an effect of less positive parental influence, school-based programs may be especially influential in increasing physical activity levels among secondary school students.

Gastrointestinal bacteria generate nitric oxide from nitrate and nitrite

Denitrifying bacteria in soil generate nitric oxide (NO) from nitrite as a part of the nitrogen cycle, but little is known about NO production by commensal bacteria. We used a chemiluminescence assay to explore if human faeces and different representative gut bacteria are able to generate NO. Bacteria were incubated anaerobically in gas-tight bags, with or without nitrate or nitrite in the growth medium. In addition, luminal NO levels were measured in vivo in the intestines in germ-free and conventional rats, and in rats mono-associated with lactobacilli. We show that human faeces can generate NO after nitrate or nitrite supplementation. Lactobacilli and bifidobacteria generated much NO from nitrite, but only a few of the tested strains produced NO from nitrate and at much lower levels. In contrast, Escherichia coli, Bacteroides thetaiotaomicron, and Clostridium difficile did not produce significant amounts of NO either with nitrate or nitrite. NO generation in the gut lumen was also observed in vivo in conventional rats but not in germ-free rats or in rats mono-associated with lactobacilli. We conclude that NO can be generated by the anaerobic gut flora in the presence of nitrate or nitrite. Future studies will reveal its biological significance in regulation of gastrointestinal integrity.

Expression of oestrogen receptor alpha and beta is higher in skeletal muscle of highly endurance-trained than of moderately active men

AIM

Two known oestrogen receptors (ERs), ERalpha and the recently cloned ERbeta, are expressed in the human skeletal muscle of both males and females. The effects of oestrogen and the role of ERs in skeletal muscle tissue are not well known. Oestrogen receptors and some of their target genes are involved in angiogenic processes. It was hypothesized that ERs are expressed at a higher level in a group with higher oxidative capacity, and that such an enhanced expression would parallel expression of the angiogenic factor -- vascular endothelial growth factor (VEGF).

METHOD

Muscle biopsies were taken from vastus lateralis in 10 highly endurance-trained males and 10 moderately active males and analysed for the expression of ERs and VEGF.

RESULTS

The major findings in the present study were the higher mRNA levels of ERalpha, ERbeta and VEGF in the highly endurance-trained than in the moderately active group.

CONCLUSION

These data suggest that the greater mRNA expression of ERalpha and ERbeta and the oestrogen-associated angiogenic factor VEGF support the hypothesis of an involvement of ERs in the adaptation of skeletal muscle to endurance training.

Measurement of the activated clotting time during cardiopulmonary bypass: differences between Hemotec ACT and Hemochron Jr apparatus

BACKGROUND

Measurement of the activated clotting time (ACT) represents a standard method for coagulatory assessments. The test employs specific agents to trigger the coagulation process. The present study aimed to compare kaolin (Hemotec) versus a combination of silica, kaolin and phospholipid (Hemochron Jr) ACTs.

METHODS

Hemotec and Hemochron Jr ACT monitors were compared by simultaneous measurement of paired arterial blood samples (n = 114) with respect to precision and bias during clinical conditions of cardiopulmonary bypass (CPB). The influence of haemodilution on the ACT was tested in an ex-vivo model.

RESULTS

The precision of Hemotec and Hemochron Jr ACT measurements attained 21 +/- 2.6 s versus 27.0 +/- 2.6 s (p = 0.126) during CPB and 2.5 +/- 2.2 s versus 9.4 +/- 6.9 s (p = 0.000) after protamine administration, respectively. The Hemochron Jr monitor was associated with a bias of -102 +/- 13.7 s compared to the Hemotec ACT monitor (p = 0.000) during CPB and -6.9 +/- 2.9 s after protamine (p = 0.025). Linear regression analysis of ACT readings between monitors reached r = 0.526 (p = 0.000). Hemochron Jr ACT values correlated with the erythrocyte volume fraction r = 0.379 (p = 0.000). Ex-vivo data indicated that the Hemotec ACT monitor was associated with relatively higher ACT readings after haemodilution.

CONCLUSION

The ACT is not a standardized measure. Test results are strongly associated with the specific compounds used to initiate the coagulation process.

VEGF-A splice variants and related receptor expression in human skeletal muscle following submaximal exercise

VEGF-A contributes to muscle tissue angiogenesis following aerobic exercise training. The temporal response of the VEGF-A isoforms and their target receptors has not been comprehensively profiled in human skeletal muscle. We combined submaximal exercise with and without reduced leg blood flow to establish whether ischemia-induced metabolic stress was an important physiological stimuli responsible for regulating the VEGF-A system in humans. Nine healthy men performed two 45-min bouts of one-leg knee-extension exercise, with and without blood flow restriction. Muscle biopsies were obtained at rest and 2 and 6 h after exercise. Expression (mRNA) of the VEGF-A splice variants and related receptors [VEGF receptor (VEGFR)-1, VEGFR-2, and neuropilin-1] was determined by using qPCR. VEGF-A(total) expression increased more robustly after exercise with reduced blood flow, and initially this principally reflected an increase in VEGF-A(165). Six hours after exercise, there was a relatively greater increase in VEGF-A(189), and this response was not influenced by blood flow conditions. VEGFR-1 mRNA expression increased 2 h after exercise, and neuropilin-1 expression was transiently reduced, while all three receptors increased by 6 h. There was no evidence for the expression of the inhibitory VEGF-A(165B) variant in human skeletal muscle. Our study, reflecting both VEGF-A ligand and receptors, implicates metabolic perturbation as a regulator of human muscle angiogenesis and demonstrates that VEGF-A splice variants are distinctly regulated. Our findings also indicate that all three receptor genes exhibit different pretranslational regulation, in response to exercise in humans.

Oestrogen receptor β is expressed in adult human skeletal muscle both at the mRNA and protein level

AIM

There are two known oestrogen receptors (ER), oestrogen receptor alpha (ERalpha) and the recently cloned oestrogen receptor beta (ERbeta). ERalpha mRNA has been detected in mouse, rat, bovine and human skeletal muscle. ERbeta mRNA has been detected in bovine skeletal muscle. To our knowledge, no study has investigated the expression of oestrogen receptor beta in human skeletal muscle. Therefore, the primary aim of the present investigation was to study ERbeta mRNA and protein expression in human skeletal muscle. In addition the ERalpha expression was also studied.

METHODS

Muscle biopsies were taken from vastus lateralis in six healthy adults (three women and three men). mRNA expression was detected with real-time PCR (TaqMan) and protein localization by immunohistochemistry.

RESULTS

A clear expression of ERalpha and ERbeta mRNA was seen in skeletal muscle in all subjects. The ERalpha mRNA expression was 180 fold higher compared with that of ERbeta mRNA. Immunohistochemistry demonstrated positive staining for ERbeta, but not for ERalpha, with localization to the nuclei of skeletal muscle fibres. On average, 70% of all nuclei were ERbeta-positive.

CONCLUSION

The present study shows for the first time ERbeta mRNA and protein expression in human skeletal muscle tissue in both males and females.

Secular trends in sports: participation and attitudes among adolescents in Sweden from 1974 to 1995

AIM

To study the secular trend (time changes) in participation in leisure-time sports activities and in attitudes towards sports activities and physical education in a representative sample of Swedish adolescents between 1974 and 1995.

METHODS

A questionnaire was distributed to 16-y-old girls and boys (n = 395 in 1974, n = 542 in 1995) to assess participation in leisure-time sports activity, attitudes towards sports activities and attitudes towards physical education at school. Height and weight were measured and body mass index (BMI) was calculated.

RESULTS

Compared with 1974, more subjects in 1995 answered that they were engaged in leisure-time sports activities, and that they were members of sports clubs. BMI increased from 1974 to 1995. By 1995, adolescents participated in and had become more interested in individual sports activities, including keep-fit activities (e.g. strength training and aerobics) compared with 1974. A gender difference in the feeling of anxiety towards physical education, with more girls experiencing it, appeared in 1995, but not in 1974.

CONCLUSION

Although more adolescents participated in leisure-time sports activity in 1995 than in 1974, the lifestyle of adolescents between sports training sessions may have become more sedentary. This is negative in a health perspective, since the benefits of physical activity on health are largely correlated to the total energy expenditure. However, the increased interest in keep-fit activities is important, since these activities have the potential to be continued into adulthood.

Secular trends in body dimensions and physical fitness among adolescents in Sweden from 1974 to 1995

AIM

To investigate changes over time in body dimensions, and muscular and aerobic fitness in a representative sample of 16-year-old-girls and boys in secondary schools in Sweden from 1974 to 1995 (n = 855).

METHOD

Height and weight were measured and five tests were performed: run-walk, two-hand-lift, Sargent jump, sit-ups, and bench-press.

RESULTS

In 1995, girls and boys had higher body mass index (BMI) than in 1974. Girls and boys performed less well in bench-press, sit-ups, and run-walk-tests in 1995. Boys, but not girls, performed better in Sargent jump in 1995 than in 1974. Girls and boys performed better in two-hand-lift in 1995 than in 1974. However, after adjustment for body dimensions, there were no differences in performance in two-hand-lift or run-walk-tests between 1974 and 1995.

CONCLUSION

There was a decreased aerobic fitness and an increased maximal static strength among adolescents in Sweden between 1974 and 1995. These changes were partly due to increased BMI. However, decreased daily physical activity level cannot be excluded as a contributing factor to the decreased aerobic fitness. The reduced performance in muscular endurance in 1995 was not related to increased BMI. Instead, it is suggested that it is to be related to a specific decrease in hip flexion and arm muscle endurance.

Bone formation after 4 weeks around blood-plasma-modified titanium implants with varying surface topographies: an in vivo study

The aim of the present study was to investigate and compare the stability and bone ingrowth capacity to screw-shaped titanium implants with five different surface treatments. The implants were: (1) standard turned with a thin blood plasma coat (TP), (2) NaOH-etched dito with pore size 0.2-0.3 microm (E), (3) NaOH-etched with pore size 0.2-0.3 microm and a thin blood plasma coat (EP), (4) electrochemically oxidised with pore size 1-2 microm (O), (5) electrochemically oxidised with pore size 1-2 microm and a thin blood plasma coat (OP). A total of 66 implants were divided into the above-described five groups and inserted for 4 weeks into tibia and femur of 11 rabbits. The implants were evaluated by resonance frequency (RF) measurements at the time of insertion and removal, and analysed histomorphometrically at removal. The RF measurements showed that the implant stability was lower in soft bone compared to dense and increased with time. No significant differences were observed between the different surface modifications. The histomorphometric analysis revealed no statistically significant differences between the implants regarding bone-to-metal contact (BMC) and bone area inside the threads (BA). The above results indicate that thin blood plasma-coated and non-coated screw-shaped titanium implants with turned, NaOH-etched and electrochemically etched surface profiles integrate similarly to bone at 1 month of implantation.

Increased expression of vascular endothelial growth factor in human skeletal muscle in response to short-term one-legged exercise training

The effects of short-term exercise training on vascular endothelial growth factor (VEGF) and one of its regulatory transcription factors, the hypoxia inducible factor 1 (HIF-1) subunit, were studied in eight healthy males. Muscle and blood samples were obtained before the 1st, and 24 h after the 7th training session. VEGF and HIF-1 mRNA were analysed using RT-PCR, VEGF mRNA localization with in situ hybridization and VEGF protein with ELISA. Concurrent increases in VEGF mRNA and protein levels were observed in skeletal muscle, and the mRNA was expressed within the skeletal muscle fibres and in cells in the interstitium. These data support the idea of a pretranslational regulation of exercise-induced changes in VEGF mRNA, and indicate that increased VEGF protein expression is an early event in skeletal muscle adaptation to training. Furthermore, different cell types may act as sources for the production of angiogenic factors in response to exercise. The levels of HIF-1 mRNA subunits did not change, suggesting no change in HIF-1 mRNA transcript levels in the regulation of training-induced VEGF expression. In contrast to increased tissue VEGF expression, the arterial and femoral venous plasma levels of VEGF were decreased by training, which may indicate an exercise-induced enhancement of the peripheral uptake of VEGF.

Use of heparin-bonded circuits in cardiopulmonary bypass improves clinical outcome

OBJECTIVE

The use of heparin-coated surfaces in cardiopulmonary bypass has been shown to decrease the inflammatory response imposed by the contact between blood and artificial surfaces. One would expect this reaction to improve clinical outcome. However, this has been difficult to verify. This investigation is based on an aggregation of two randomized studies from our institution and highlights possible effects of heparin coating on a number of clinically oriented parameters.

DESIGN

Departmental analysis of patients subjected to coronary artery bypass surgery using heparin-coated circuits. Cardiopulmonary bypass was employed using either the Carmeda or Duraflo heparin coatings compared with a control. The systemic heparin dose was reduced in the heparin-coated groups (ACT > 250 s) vs control group patients (ACT > 480 s). The effects of heparin coating related to clinical outcome were studied.

RESULTS

The use of heparin-coated circuits reduced the mean length of stay in hospital from 7.8 +/- 2.5 to 7.3 +/- 1.8 days (p = 0.040) and postoperative ventilation time from 9.7 +/- 9.2 to 8.2 +/- 8.5 h (p = 0.018), blood loss 8 h post surgery from 676 +/- 385 to 540 +/- 245 ml (p = 0.001), individual perioperative change of haemoglobin loss (p = 0.001), leukocyte count (p = 0.000) and creatinine elevation (p = 0.000), proportion of patients exposed to allogenous blood transfusions 39.2 vs 23.9% (p = 0.001), postoperative coagulation disturbances 4.4 vs 0.4% (p = 0.006), postoperative deviations from the normal postoperative course 47.2 vs 36.7% (p = 0.035), neurological deviations 9.4 vs 3.9% (p = 0.021) and atrial fibrillation 26.4 vs 18.0% (p = 0.041). No effects were found with respect to perioperative platelet count, postoperative fever reaction and 5-year survival.

CONCLUSION

Based on several indicators, the use of heparin coating in cardiopulmonary bypass is associated with improved clinical results.

Ultrasound-guided percutaneous biopsies of the semitendinosus muscle following ACL reconstruction--a methodological description

PURPOSE

To evaluate whether the ultrasound-guided biopsy technique could be used to analyse the histochemical profile of m. semitendinosus following ACL reconstruction with autologous semitendinosus tendon graft.

MATERIAL AND METHODS

Sixteen patients were included in the study. During ACL surgery, specimens from m. semitendinosus were obtained via open biopsy. Ultrasound-guided biopsies from m. semitendinosus were performed 7 - 11 months postoperatively from operated leg (n = 16) and non-operated leg (n = 8).

RESULTS

Two biopsy samples were pooled and formed a specimen of approximately 150 fibres. For fibre type composition, there was correlation between open biopsy and ultrasound-guided biopsy data, (P = 0.003, r = 0.89). The r-value for mean fibre area was 0.72 (P = 0.06). The methodological error for fibre type 1 % and mean fibre area was 9 %. Postoperatively, no significant differences were found in fibre type composition or fibre type areas between the operated and non-operated leg.

CONCLUSION

Ultrasound-guided biopsy is an easy and safe technique that can be used for scientific studies and in clinical practice where biopsy from small muscles or from special location in muscles, such as in ruptures, scars or others is needed.

Lactate concentrations in human skeletal muscle biopsy, microdialysate and venous blood during dynamic exercise under blood flow restriction

The intramuscular microdialysate lactate concentration during dynamic exercise with various degrees of blood flow restriction and its relation to lactate concentration in skeletal muscle biopsy and venous blood were studied. Nine healthy males performed three one-legged knee extension exercises (Ex 1-3). Blood flow was restricted stepwise by applying supra-atmospheric pressure over the working leg. Microdialysate mean (range) lactate concentrations at the end of the exercise periods were 3.2 (0.5-6.6), 4.4 (1.1-9.8) and 7.9 (1.1-11.6) mmol.l(-1)during unrestricted, moderately restricted and severely restricted blood flow respectively. There was a significant correlation between microdialysate and venous lactate concentrations at the end of all three exercise periods. Microdialysate lactate concentration correlated significantly to skeletal muscle biopsy lactate concentration at the end of Ex 1. In conclusion, microdialysate lactate concentration in the working muscle increased step-wise with increasing blood flow restriction. It showed a better correlation to venous than to muscle biopsy lactate, which is possibly partly explained by the characteristics of diffusion between body compartments and differences in time resolution between the methods used.

On the formation of fibrous capsule and fluid space around machined and porous blood plasma clot coated titanium

Machined and machined submicron porous titanium, with and without a thin blood plasma coating (100 nm), were implanted for 7 or 28 days in subcutaneous pockets on the back of the rat. After explantation the specimens were analyzed by light microscopy with respect to thickness of the fibrous capsule, the fluid space width between implants and fibrous capsule, and formation of blood vessels. The results at 7 days indicate a thinnest fluid space for the plasma clot coated porous titanium surface, and the spaces vanished at the light microscopic level after 28 days outside all the analyzed surfaces. The thickness of the fibrous capsule increased outside the different surfaces at 7-28 days, and in this respect no significant differences were observed between the different surfaces at any time. Analysis of neovascularization showed that the number of vessels and proportion of vessels in the fibrous capsule increased with time at all surfaces, except machined Ti where the number instead decreased from 7 to 28 days. The average distance between the blood vessels and the fluid space increased with time for all types of surfaces. The results in the present study indicate that the healing process around titanium can be modulated by porosity and thin pre-prepared plasma coatings.

Semitendinosus muscle in anterior cruciate ligament surgery: Morphology and function

PURPOSE

To evaluate the fate of the hamstring muscles in general and the semitendinosus muscle in particular, after anterior cruciate ligament (ACL) reconstruction with an autologous semitendinosus tendon graft from the ipsilateral side.

TYPE OF STUDY

Prospective consecutive case series investigation.

METHODS

Included were 16 consecutive patients, 14 male and 2 female, with a mean age of 26 years. The inclusion criterion was chronic unilateral ACL insufficiency with no concomitant knee ligament injuries. ACL reconstruction was performed with a quadruple semitendinosus tendon graft using the EndoButton technique (Acufex, Mansfield, MA). Intraoperatively, muscle specimens were taken from the semitendinosus muscle on the harvested side. Follow-up at a minimum of 6 months included clinical examination, isokinetic strength performance, magnetic resonance imaging (MRI) of the thigh and knee, and ultrasound-guided muscle biopsy procurement from the semitendinosus muscle for histochemical and enzymatic analyses.

RESULTS

Of the patients, 75% showed regeneration of their semitendinosus tendons. The neotendons all inserted below the knee joint where they had fused with the gracilis tendon to a conjoined tendon inserting in the pes anserinus. The semitendinosus muscle had a smaller cross-sectional area on the operated side but none showed total atrophy. Less atrophy was present in the patients with a regenerated semitendinosus neotendon compared with those without regeneration (P =.029). In the latter group the semimembranosus muscle seemed to compensate for this with hypertrophy (P =.019). Cross-sectional muscle fiber areas, the relative number of each fiber type and oxidative potential as estimated by citrate synthase activity, showed no significant differences between the operated and nonoperated legs. The isokinetic strength of the hamstrings and quadriceps was significantly lower in the operated leg than in the nonoperated leg.

CONCLUSIONS

With this surgical technique, the semitendinosus muscle can recover and the tendon has, according to the MRI images, a great potential to regenerate after its removal.

Mitochondrial transcription factor A and respiratory complex IV increase in response to exercise training in humans

Protein levels of mitochondrial transcription factor A (Tfam) and nuclear- and mitochondrial-encoded subunits of respiratory chain complex IV (COX I and COX IV) as well as citrate synthase activity were analysed in muscle biopsy samples of vastus lateralis in six healthy male subjects before and after 4 weeks of one-legged cycle training. One leg was trained with restricted blood flow. The other leg was trained with the same power profile but with non-restricted blood flow. Tfam, COX I and COX IV levels all increased with training, with no differences observed between the legs. The training-induced increase in citrate synthase activity was greater in the leg trained with restricted blood flow. These findings indicate that changed expression of Tfam protein could be one mechanism of exercise-induced mitochondrial biogenesis. The increases of COX I and COX IV indicate a concurrent increase of nuclear- and mitochondrial-encoded subunits of respiratory enzyme complex IV at the protein level in skeletal muscle in response to increased muscle activity. In this study, it was not possible to demonstrate that the greater energy disturbance induced by reduced blood flow further stimulates the expression of mitochondrial proteins, even though it did cause a greater enhancement of citrate synthase activity in concordance with earlier studies.

Adolescent determinants of cardiovascular risk factors in adult men and women

AIMS

To investigate how physical activity, physical performance and sociodemographic characteristics at the age of 16 are related to adult health habits (physical activity, dietary intake, smoking) and biological risk factors for cardiovascular diseases (being overweight, low aerobic fitness, unfavorable levels of serum lipids, high blood pressure).

METHODS

A randomly selected group of 220 male and 205 female students at 16 years of age was tested in 1974, and reinvestigated 18 years later.

RESULTS

The predictive health profiles for adult lifestyle and biological risk factors were different in men and women. Leisure sports activity along with high performance in the nine-minute run among the boys and in the two-hand lift test among the girls were significant predictors of adult physical activity. A positive attitude to aerobic exercise and high performance in the nine-minute run test among the boys and high marks in physical education among the girls decreased the risk of smoking. Leisure sports activities together with body mass index at young ages were the most powerful predictors of adult biological risk factors, but attitudes to sports and educational level were also significant determinants.

CONCLUSION

These results contribute to the knowledge of which factors at young ages may promote adult healthy habits in particular physical activities.

In vitro preparation and ellipsometric characterization of thin blood plasma clot films on silicon

The wound-healing process around implants differs from that of a normal healing without the inserted material. In this work, the composition of a natural wound surface was mimicked through clotting of a thin human blood plasma film with approximate ellipsometric thickness of 100 nm onto differently pretreated silicon surfaces. Their stability was investigated by incubations in sodium dodecyl sulphate (SDS) solutions. The enzymatic clot degradation was induced through addition of human tissue plasminogen activator (t-PA) to the plasma and the surface protein remnants after the degradation were analyzed with polyclonal antibodies. The results show that the plasma films were not SDS resistant on hydrophilic silicon. However, stability was obtained after preparation on hydrophobic silicon or when albumin or fibrinogen was immobilized to silicon before the plasma incubations. Different surfaces bound different polyclonal antibodies after the clot film degradation. The methods indicate a simple means to improve or reestablish a normal tissue inflammatory response around biomaterials.

Regulation of skeletal muscle ATP catabolism by AMPD1 genotype during sprint exercise in asymptomatic subjects

Deficiency of myoadenylate deaminase, the muscle isoform of AMP deaminase encoded by the AMPD1 gene, is a common myopathic condition associated with alterations in skeletal muscle energy metabolism. However, recent studies have demonstrated that most individuals harboring this genetic abnormality are asymptomatic. Therefore, 18 healthy subjects with different AMPD1 genotypes were studied during a 30-s Wingate test in order to evaluate the influence of this inherited defect in AMPD1 expression on skeletal muscle energy metabolism and exercise performance in the asymptomatic population. Exercise performances were similar across the AMPD1 genotypes, whereas significant differences in several descriptors of energy metabolism were observed. Normal homozygotes (NN) exhibited the highest levels of AMP deaminase activities, net ATP catabolism, and IMP accumulation, whereas intermediate values were observed in heterozygotes (MN). Conversely, mutant homozygotes (MM) had very low AMP deaminase activities and showed no significant net catabolism of ATP or IMP accumulation. Accordingly, MM also did not show any postexercise increase in plasma ammonia. Unexpectedly, MN consistently exhibited greater increases in plasma ammonia compared with NN despite the relatively lower accumulation of IMP in skeletal muscle. Moreover, time course profiles of postexercise plasma ammonia and blood lactate accumulation also differed across AMPD1 genotypes. Finally, analysis of adenosine in leftover biopsy material revealed a modest twofold increase in MN and a dramatic 25-fold increase in MM.