Muscle indices do not fully account for enhanced upper extremity bone mass and strength in gymnasts.

OBJECTIVES: Muscular forces are an important determinant of bone strength, but bone may also adapt to non-muscular loading. We tested the hypothesis that loads associated with childhood gymnastics yield high arm bone mass (BMC), bone size and bone strength, independent of arm lean mass (FFM) and muscle cross-sectional area (CSA). METHODS: Total body DXA and distal radius pQCT scans were performed on 33 post-menarcheal girls (19 ex/gymnasts, 14 non-gymnasts). Physical activity and calcium intake were assessed by questionnaire. For the non-dominant arm, pQCT measured bone strength indices and bone CSA (total, cortical) (4%, 33% sites); DXA measured arm FFM, arm BMC and skull BMC. Multiple regression analyses assessed gymnastic exposure, arm FFM, gynecological age and stature as predictors of bone parameters. RESULTS: Bone outcomes at loaded upper extremity sites were 10-42% greater in ex/gymnasts than non-gymnasts. Gymnastic exposure remained a consistent, significant predictor of upper extremity skeletal parameters after accounting for the effects of muscle parameters, gynecological age and height. CONCLUSIONS: Considering the effects of either arm FFM or muscle CSA, indices of bone mass, geometry and theoretical strength are disproportionately elevated after gymnastic exposure. Thus, non-muscular loading may be a distinct and important determinant of human skeletal structure.

The effects of inhibition of plasma cholinesterase and hepatic microsomal enzyme activity on cocaine, benzoylecgonine, ecgonine methyl ester, and norcocaine blood levels in pigs.

We measured the blood levels of cocaine and its three major metabolites, benzoylecgonine, ecgonine methyl ester, and norcocaine, in three groups of male pigs weighing about 26 kg (25.75 +/- 0.25 kg) to determine the effects of inhibition of plasma cholinesterase and hepatic microsomal enzyme activity on cocaine metabolism. In addition, systemic elimination half-life, volume of distribution, and clearance of cocaine were calculated for the three groups. Group 1 pigs (n = 4) were pretreated with normal saline solution, group 2 pigs (n = 4) were pretreated with tetraisopropyl pyrophosphoramide, a specific plasma cholinesterase inhibitor, and group 3 pigs (n = 4) were pretreated with cimetidine, a hepatic microsomal enzyme inhibitor, all administered intramuscularly. Pigs were anesthetized with intravenous sodium thiopental; a carotid arterial cannula and an external jugular catheter were then inserted for the administration of cocaine and for blood sampling. Forty-five minutes later, when pigs were again completely awake, cocaine 3 mg/kg was given intravenously. Arterial blood samples were collected for the analysis of cocaine and cocaine metabolite levels just before and at 5, 10, 15, 30, 45, 60, 120, 180, and 1440 minutes after the administration of cocaine. Cocaine and cocaine metabolite blood levels were analyzed with high-pressure liquid chromatography methods and plasma cholinesterase activity was measured with a colorimetric method. The blood levels of cocaine and cocaine metabolites were significantly different among the three groups (p less than 0.05, analysis of variance). Statistically significant differences in half-life, volume of distribution and clearance were also seen among the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)