ABSTRACT
OBJECTIVE: The purpose of this investigation is to analyze childhood blood lead levels and growth status (ages 2-12) in Dallas, Texas lead smelter communities in the 1980s and 2002, where smelters operated from 1936 to 1990. METHODS AND MATERIALS: A sample of convenience study design was used in two cohorts (n=360): 1980-1989 (n=191) and 2002 (n=169). Multivariate analysis of variance and covariance and tandem multiple regressions were used to evaluate the association between stature and blood lead level in two time periods. RESULTS: In 2002 average child blood lead level (1.6 microg/dL+/-0.2 SE) was significantly (p<0.001) lower compared to the 1980 cohort mean level (23.6 microg/dL+/-1.3 SE). Average height and weight in 2002 were 4.5 cm and 4.0 kg greater, respectively, than in 1980. Lowered blood lead level was associated with 3.9 cm, 3.5 kg and 1.1 units greater height, weight and body mass index (BMI), respectively. Cohort effect was associated with greater height (0.6 cm), weight (0.5 kg) and BMI (0.1). CONCLUSION: This investigation reports on child growth in a community before and after the transition from high to low blood lead levels over several decades. Using child growth as a proxy, health status of Dallas's lead smelter communities increased markedly over the past two decades, primarily because of lower blood lead levels, while the poverty rate was only marginally lower.
Subject(s)
Black or African American/statistics & numerical data , Environmental Exposure , Growth Disorders/epidemiology , Hispanic or Latino/statistics & numerical data , Lead/blood , Metallurgy , Body Height , Body Mass Index , Body Weight , Child , Child, Preschool , Cohort Studies , Female , Follow-Up Studies , Growth Disorders/blood , Growth Disorders/etiology , Humans , Infant , Lead/adverse effects , Male , Poverty , Texas/epidemiology , Urban Population/statistics & numerical dataABSTRACT
In female Wistar rats (n = 316) under pentobarbital sodium anesthesia, the soleus muscle was autografted with its nerve reimplanted. One purpose was to characterize the chronological development of graft innervation and recruitment during locomotion. Furthermore, we tested hypotheses regarding the efficacy of run conditioning of different intensities, durations, and postgrafting initiation times to alter mass and pyruvate-malate oxidation capacity of grafts. Choline acetyltransferase activity of grafts increased from 10% of control value at 7 days postgrafting to 55 and 100% at days 28 and 56, respectively. Running-induced glycogen depletion occurred in grafts; this is consistent with graft recruitment during locomotion. There was a threshold of conditioning intensity below which no improvements occurred and above which there were improvements. Spring (50 m/min) and endurance (30 m/min) conditioning of a duration of at least 28 days that was initiated at 28 or 56 days postgrafting increased mass of grafts by 30% compared with grafts from nonconditioned rats. Easy conditioning (15 m/min) had no effect on graft mass. Changes in graft total protein content paralleled those of mass. Oxidation capacity of grafts increased significantly with some conditioning protocols, but not to the same extent as mass. The exercise-induced adaptations should improve graft function in the host organism.
Subject(s)
Muscles/transplantation , Nerve Regeneration , Physical Exertion , Animals , Choline O-Acetyltransferase/metabolism , Female , Glycogen/metabolism , Hindlimb/innervation , Motor Endplate/physiology , Muscle Contraction , Muscle Proteins/metabolism , Muscles/innervation , Rats , Rats, Inbred StrainsSubject(s)
Energy Metabolism , Jogging , Running , Adult , Body Weight , Female , Humans , Male , Middle AgedABSTRACT
One hundred fifteen high school football players were screened isokinetically for the knee extensor and flexor torque generating capabilities and muscle imbalances. Each player was tested on a Cybex II at speeds of 30 degrees/sec and 180 degrees/sec. The subjects were stratified by age (15, 16, 17) and by position (linemen vs receivers and backs). Significant (p less than 0.05) torque differences were observed at both the slow and fast speeds for the knee extensors and flexors across the 3 age groups. However, the flexion to extension ratios did not differ significantly. On the other hand, when considering the positions, flexor torque and flexion to extension ratio at the slow speed were greater (p less than 0.05) for the linemen than the receivers and backs. Partial correlation analyses showed that body weight had the greatest effect on the knee torque values. It was concluded that basic torque measures differed with age and by position in the sport of football. Also, speed of movement altered the force generating capabilities of the muscle and resultant ratios.
