Osteocalcin and its forms respond similarly to exercise in males and females.

INTRODUCTION: Acute exercise increases osteocalcin (OC), a marker of bone turnover, and in particular the undercarboxylated form (ucOC). Males and females differ in baseline levels of total OC and it is thought the hormonal milieu may be driving these differences. Males and females adapt differently to the same exercise intervention, however it is unclear whether the exercise effects on OC are also sex-specific. We tested whether the responses of OC and its forms to acute High Intensity Interval Exercise (HIIE) and High Intensity Interval Training (HIIT) differed between males and females. Secondly, we examined whether sex hormones vary with OC forms within sexes to understand if these are driving factor in any potential sex differences. METHODS: Total OC (tOC), undercarboxylated OC (ucOC), and carboxylated OC (cOC) were measured in serum of 96 healthy participants from the Gene SMART cohort (74 males and 22 females) at rest, immediately after, and 3 h after a single bout of HIIE, and at rest, 48 h after completing a four week HIIT intervention. Baseline testosterone and estradiol were also measured for a subset of the cohort (Males = 38, Females = 20). Linear mixed models were used to a) uncover the sex-specific effects of acute exercise and short-term training on OC forms and b) to examine whether the sex hormones were associated with OC levels. RESULTS: At baseline, males had higher levels of tOC, cOC, and ucOC than females (q < 0.01). In both sexes tOC, and ucOC increased to the same extent after acute HIIE. At baseline, in males only, higher testosterone was associated with higher ucOC (ß = 3.37; q < 0.046). Finally, tOC and ucOC did not change following 4 weeks of HIIT. CONCLUSION/DISCUSSION: While there were no long-term changes in OC and its forms. tOC and ucOC were transiently enhanced after a bout of HIIE similarly in both sexes. This may be important in metabolic signalling in skeletal muscle and bone suggesting that regular exercise is needed to maintain these benefits. Overall, these data suggest that the sex differences in exercise adaptations do not extend to the bone turnover marker, OC.

The relationship between metformin therapy and the fasting plasma lactate in type 2 diabetes: The Fremantle Diabetes Study.

AIMS: To determine (i) which factors, including metformin, are associated with the fasting plasma lactate concentration in type 2 diabetes, and (ii) whether plasma lactate is associated with haemodynamic and metabolic effects. METHODS: We measured fasting plasma lactate in 272 well-characterized diabetic patients from a community-based sample, 181 (67%) of whom were taking metformin with or without other therapies. Linear regression analysis was used to identify predictors, including metformin therapy, of the plasma lactate, and to investigate associations between plasma lactate and resting pulse rate and serum bicarbonate. Factor analysis assessed independent relationships between groups of cosegregating variables. RESULTS: Metformin-treated patients had higher plasma lactate concentrations than nonmetformin-treated subjects (geometric mean [s.d. range] 1.86 [1.34-2.59] vs 1.58 [1.09-2.30] mmol x l(-1), respectively; P < 0.001). In a linear regression model, plasma glucose, BMI and metformin use (but not dose) were independently associated with plasma lactate (P < or = 0.028); after adjustment for the former two variables, metformin-treated patients had a mean plasma lactate 0.16 mmol l-1 greater than in subjects not taking the drug. Factor analysis revealed that plasma lactate, plasma glucose, BMI and pulse rate cosegregated but serum bicarbonate was not in this grouping. CONCLUSIONS: The present results show that metformin therapy increases the fasting plasma lactate in ambulant patients with type 2 diabetes from a community-based cohort. From associations in the data we hypothesize that this increase reflects (i) increased sympathetic activity in patients with the metabolic syndrome (ii) increased substrate (glucose) availability and (iii) a direct metformin effect.

Progression of skeletal muscle damage during treatment of severe falciparum malaria.

To assess the relationship between severity of malaria and progression of skeletal muscle damage during initial treatment, we studied 28 Thai adults with slide-positive falciparum malaria. Six had uncomplicated malaria (Group 1), 12 had severe non-cerebral malaria (Group 2) and ten had cerebral malaria (Group 3). There were no significant differences between baseline serum creatine kinase (CK) levels in the three groups (P=0.071). There was no change in serum CK during the first 48 h of treatment in Group 1 cases. In Group 2 patients, the median peak serum CK was nine times that at baseline while in Group 3, serum CK peaked at a median concentration 20 times that at presentation. In Groups 2 and 3, the peak serum CK occurred at least 24 h after presentation in more than half the patients, and was independent of intramuscular injections and convulsions during initial therapy. These longitudinal data suggest that: (i) severe falciparum malaria is associated with skeletal muscle damage that increases during initial therapy especially in patients with coma; (ii) the effect of other major treatment or infection-specific factors that are associated with muscle damage does not diminish this relationship; and (iii) cerebral malaria in combination with a high baseline and rising serum CK should pre-empt monitoring and management strategies aimed at preserving renal function including renal dialysis.