Comparison of the effects of pentagastrin and meal-stimulated gastrin on plasma calcitonin in normal man

We compared the effects of exogenous pentagastrin and meal-stimulated gastrin on plasma immunoreactive calcitonin (iCT) in various studies of 13 normal adult men. Bolus intravenous injection of pentagastrin (0.5 μg/kg) produced increases of iCT in 8 of 9 men. There was a linearly increasing response of iCT concentrations to increasing doses of pentagastrin (0.0625, 0.125, 0.25, and 0.5 μg/kg) and to achieved serum immunoreactive pentagastrin concentrations (r=0.72, P<0.01). To determine the effects of endogenous gastrin upon peripheral iCT concentrations, we measured serum immunoreactive gastrin (iG) and plasma iCT in four men at frequent intervals for 240 min after ingestion of low-(100 mg) and high- (400 mg) calcium meals. Serum iG increased in all subjects, with a peak at ～30 min. However, plasma iCT levels were unchanged from basal throughout the study. The increase of pentagastrin (0.3 pmol/ml) which caused a barely detectable increase of iCT was five-to tenfold greater than the mean maximal increases of gastrin after low- and high-calcium meals (0.04 and 0.06 pmol/ml, respectively). These results suggest that increases of plasma iCT concentrations after administration of pentagastrin in man reflect pharmacologic phenomena and that postprandial gastrin secretion may be insufficient to affect peripheral iCT concentrations.     

Genetic and environmental influences on the rate of progression to alcohol dependence in young women

Background: The development of alcohol dependence (AD) involves transitions through multiple stages of drinking behaviors and is shaped by both heritable and environmental influences. We attempted to capture this dynamic process by characterizing genetic and environmental contributions to the rate at which women progressed through 3 significant transitions along the pathway to AD: nonuse to initiation, initiation to onset of first alcohol‐related problem, and first problem to onset of AD. Methods: The sample consisted of 3,546 female twins from the Missouri Adolescent Female Twin Study. Participants ranged in age from 18 to 29 years. Retrospective reports of alcohol use histories were collected by telephone diagnostic interview and transition times between drinking milestones were coded ordinally. Standard genetic analyses were conducted in Mx to derive a trivariate model that provided estimates of genetic and environmental influences that were common as well as specific to the 3 transition times. Results: Heritable influences were found for rate of progression across all 3 transitions, accounting for 30 to 47% of the variance in transition times. Shared environmental contributions were evident only in rate of progression from nonuse to initiation (i.e., age at first drink). Heritable contributions to the rate of movement through successive drinking milestones were attributable to a common factor, whereas environmental influences were transition‐specific. Conclusions: The current study is unique in its use of a genetically informative design to document the rate of movement between drinking milestones in a female sample and to examine genetic contributions to multiple transition times over the course of AD development. Results indicate that an earlier report of heritability for males in rate of progression from regular drinking to AD generalizes to women and to other alcohol stage transitions. Findings also suggest the need to consider stage‐specific environmental contributions to alcohol outcomes in developing interventions.     

Injury Prevention in Baseball: from Youth to the Pros

Purpose of Review

This review examines recent literature on injury epidemiology and prevention in the sport of baseball from youth to professional levels.

Recent Findings

Overuse is the predominant mechanism of injury in youth baseball players. Newer stretching and exercise protocols may help prevent these injuries. At the professional level, however, overuse has not been proven to correlate with increased injury incidence, but pitch counts are still monitored. There continues to be a rise in operations performed for baseball-related injuries, including ulnar collateral ligament (UCL) reconstruction, particularly in younger athletes. As the level of play increases, there is significant loss of participation due to injuries, such as the UCL in the upper extremity and the hamstrings in the lower extremity.

Summary

Baseball is a widely popular sport, which has led to a focus on injury epidemiology and prevention. While the majority of research regarding baseball injuries focuses on pitchers, fielders and catchers are also at risk. In an attempt to decrease non-contact injuries in the upper and lower extremities, stretching and strengthening exercises are vitally important. Because injury profiles demonstrate significant variability from youth to professional baseball, unique prevention strategies are likely necessary at each level. More research is needed to develop and validate appropriately targeted injury prevention programs.