New Findings r What is the central question of this study?Does intense intermittent exercise provide a sufficient angiogenic stimulus to induce capillary growth in skeletal muscle conditioned by moderate intensity exercise training? r What is the main finding and its importance?We show that higher levels of shear stress and metabolism associated with intense exercise do not provide further stimulus for capillary growth. Instead, secretion of vascular endothelial growth factor and proliferation of endothelial cells are lower in response to intense compared with moderate-intensity exercise, suggesting that intense exercise is a weaker stimulus for angiogenesis. The data provide novel insight into the regulation of vascular endothelial growth factor secretion in muscle and the role of pro-angiogenic and angiostatic factors.The effect of acute intense intermittent exercise compared with moderate-intensity exercise on angiogenic factors and the effect of 4 weeks of intense intermittent training on capillary growth were examined in nine healthy young men, preconditioned by moderate-intensity endurance training. The intense training consisted of 24 bouts of 1 min cycling at an initial work rate of 316 ± 19 W (∼117% of pretraining maximal oxygen uptake), performed three times per week. Skeletal muscle biopsies and muscle microdialysates were otained from the vastus lateralis before, during and after acute exercise performed at either moderate or high intensity. Comparison of the response in angiogenic factors to acute moderate-versus high-intensity exercise, performed prior to the intense training intervention, revealed that intense exercise resulted in a markedly lower (∼60%; P < 0.05) increase in interstitial vascular endothelial growth factor than did moderateintensity exercise. Muscle interstitial fluid obtained during moderate-intensity exercise increased endothelial cell proliferation in vitro more than interstitial fluid obtained during intense exercise (sixfold versus 2.5-fold, respectively; P < 0.05). The 4 weeks of high-intensity training did not lead to an increased capillarization in the muscle but abolished the exercise-induced increase in mRNA for several angiogenic factors, increased the protein levels of endothelial nitric oxide synthase, lowered the protein levels of thrombospondin-1 in muscle but increased the interstitial protein levels of thrombospondin-1. We conclude that intense intermittent exercise provides a weak stimulus for vascular endothelial growth factor secretion and endothelial cell proliferation

Serum creatine-kinase (CK) and pyruvate-kinase (PK) levels were determined in 201 boys and girls less than 15 years old to establish values and to investigate a possible correlation between enzyme activity, sex, and age. It was observed that the mean CK activity in boys was significantly higher than in females (of all ages), whereas it did not differ statistically between girls and women. A slight but significant correlation between CK activity and age was found only in females. The mean PK activity in children was significantly greater than in adult women and it decreased significantly with age in children of both sexes. Furthermore, a slight correlation between CK and PK was observed only in girls. Based on these results, we suggest that the results of CK and PK determinations of females at risk for Duchenne muscular dystrophy should be compared with controls of comparable age and sex.

No abstract

Creatine-kinase (CK) and pyruvate-kinase (PK) were determined in cord blood samples from 125 normal newborn infants in order 1) to investigate the correlation between CK and PK, 2) to evaluate a possible influence of the mode of delivery (cesarean section versus vaginal delivery) and birth weight on enzyme activity, 3) to establish normal values for both sexes. In the present investigation, the enzyme activities of cord blood were significantly higher than in the normal adult, and no correlation was observed between enzyme activity and mode of delivery or birthweight. Although there was an apparent and significant correlation (r = 0.5) between CK and PK levels in cord blood samples, in no case did we find both high CK and PK values, something that would suggest preclinical DMD or a false-positive result. These results have led us to suggest determination of serum PK activity in male newborn screening programs. This would allow an early discrimination between false-positives and clinical cases already in the neonatal period. Furthermore, the concomitant use of PK and CK in boys not walking by 18 months could be a useful test for diagnosing preclinical DMD boys.