Weight loss and wrestling training: effects on growth-related hormones

Roemmich, James N., and Wayne E. Sinning. Weight lossand wrestling training: effects on growth-related hormones.J. Appl. Physiol. 82(6):1760-1764, 1997.Adolescent wrestlers(n = 9, 15.4 yr) and recreationallyactive control males (n = 7, 15.7 yr)were measured before, at the end of, and 3.5-4 mo after acompetitive wrestling season to assess the influence of dietary restriction on growth-related hormones. Wrestlers had significant elevations preseason to late season for morning serum concentrations (mean of 8 serial samples) of growth hormone (GH; 2.9 ± 0.7 vs. 6.5 ± 1.4 ng/ml) and sex hormone-binding globulin (SHBG; 16.1 ± 2.3 vs. 27.9 ± 6.9 nmol/l) and significant reductions in GH-binding protein (GHBP; 178 ± 19 vs. 109 ± 17 pmol/l), insulin-likegrowth factor I (IGF-I; 332 ± 30 vs. 267 ± 34 ng/ml),testosterone (T; 4.9 ± 0.4 vs. 3.6 ± 0.4 ng/ml), and freetestosterone (Free-T; 22.4 ± 3.6 vs. 15.7 ± 2.8 pg/ml).Wrestlers had significant postseason reductions in GH (3.44 ± 1.30 ng/ml) and SHBG (10.43 ± 4.13 nmol/l) but elevationsin GHBP (66.7 ± 23.8 pmol/l), IGF-I (72.9 ± 25.1 ng/ml),T (2.10 ± 0.46 ng/ml), and Free-T (9.76 ± 3.01 pg/ml). Concentrations of luteinizing hormone (LH), estradiol,prolactin, cortisol, insulin, and thyroid hormones did not differbecause of exercise-dietary practices of wrestlers. In-seasonelevations in GH, with concomitant reductions in GHBP and IGF-I, thatwere reversed during the postseason suggest a reduction in GH receptor number and partial GH resistance during the season. Nonelevated LH withreduced T levels suggests a central hypothalamic-pituitary-gonadal (H-P-G) axis impairment. In conclusion, undernutrition may lead toaltered H-P-G and GH-IGF-I axes function in adolescent wrestlers. However, only the wrestlers' late-season Free-T concentrations wereoutside the normal range, and the hormone axis impairments were quicklyreversed. The present data do not address hormonal axis responses toseveral years of wrestling and weight loss.

     

Increase in percutaneous muscle biopsy yield with a suction-enhancement technique

Hennessey, James V., Joseph A. Chromiak, ShirleyDellaVentura, Jennifer Guertin, and David B. MacLean. Increasein percutaneous muscle biopsy yield with a suction-enhancementtechnique. J. Appl. Physiol. 82(6):1739-1742, 1997.The percutaneous muscle biopsy technique is usedin clinical practice and biomedical research. We developed a newenhanced-suction technique [suction-enhancing nipples(SEN)] and compared it with techniques currently in practice byassessing biopsy yields on anesthetized pigs. We applied the enhanced-suction technique to human subjects participating in aclinical trial. In the pig, there was a mean 91% (1.9-fold) increasein the size of the samples obtained with the 4-mm needle when SEN wasused and a mean 507% (fivefold) increase in sample size when the SENwas applied to the 6-mm needles. Nine passes of the 6-mm needle withSEN obtained from five consecutive human subjects yielded a meanindividual sample size of 109.4 mg or 219.4 mg per needle pass whenusing the double-sample technique. Adequate tissue samples forhistomorphometric and other analyses were obtained in all samplesobtained. The percutaneous muscle biopsy performed with enhancedsuction using inexpensive, readily available nipples enhances tissueyield two- to fivefold.

     

Alterations in growth and body composition during puberty. I.Comparing multicompartment body composition models

Roemmich, James N., Pamela A. Clark, Arthur Weltman, andAlan D. Rogol. Alterations in growth and body composition duringpuberty. I. Comparing multicompartment body composition models.J. Appl. Physiol. 83(3): 927-935, 1997.A four-compartment (4C) model of body composition was used as acriterion to determine the accuracy of three-compartment (3C) andtwo-compartment (2C) models to estimate percent body fat (%BF) inprepubertal and pubertal boys (genital I & II,n = 17; genital III & IV,n = 7) and girls (breast I & II, n = 8; breast III & IV,n = 15). The 3C water-density (3C-H₂O) and 3C mineral-densitymodels, dual-energy X-ray absorptiometry, the Lohman age-adjustedequations, the Slaughter et al. skinfold equations, and the Houtkooperet al. and Boileau bioelectrical impedance equations wereevaluated. Agreement with the 4C model increased with thenumber of compartments (i.e., body water, bone mineral) measured.Except for the 3C-H₂O model, thelimits of agreement were large and did not perform well forindividuals. The mean %BF by dual-energy X-ray absorptiometry (23.6%)was greater than that of the criterion 4C method (21.7%).For the field methods, the Slaughter et al. skinfold equationsperformed better than did the Houtkooper et al. and Boileaubioimpedance equations. The hydration of the fat-free mass decreased(genital I & II = 75.7%, genital III & IV = 74.8%, breast I & II = 75.5%, breast III & IV = 74.4%) and the mineral content increased(genital I & II = 4.9%, genital III & IV = 5.0%, breast I & II = 5.1%, breast III & IV = 5.7%) with maturation. The densityof the fat-free mass also increased (genital I & II = 1.084 g/ml,genital III & IV = 1.087 g/ml, breast I & II = 1.086 g/ml, breast III & IV = 1.091 g/ml) with maturation. All of the models reduced the %BF overprediction of the Siri 2C model, but only the 4C and3C-H₂O models should be used ascriterion methods for body composition validation in children andadolescents.

     

A permanent prosthesis for converting in situ muscle contractions into hydraulic power for cardiac assist

Trumble, Dennis R., and James A. Magovern. A permanentprosthesis for converting in situ muscle contractions into hydraulic power for cardiac assist. J. Appl.Physiol. 82(5): 1704-1711, 1997.The key toutilizing muscle power for circulatory support lies with thedevelopment of a practical scheme by which contractile energy may becollected and efficiently delivered to the bloodstream. This workdescribes initial in vitro testing of a prototype muscle energyconverter (MEC) designed to transform the power of in situ musclecontractions into hydraulic form. The MEC resembles a simple pistonpump and is designed for implant beneath the humeral insertion of thelatissimus dorsi muscle. Bench tests were conducted to measurecomponent function and to characterize device performance under varioushydraulic loads. Under simulated muscle-pull conditions, MEC energytransfer capacity was found to be 170 mJ/stroke while operating at peakefficiencies (i.e., >98% of input power converted into hydraulicenergy and preload work). Transfer efficiencies dropped from 96 to 38%as mean generated pressures increased from 23 to 36 N/cm² due to metal bellowsflexion. These results demonstrate that a significant amount ofcontractile energy can be efficiently transformed to hydraulic powervia this mechanism.

     

Strength, skeletal muscle composition, and enzyme activity in multiple sclerosis

Kent-Braun, J. A., A. V. Ng, M. Castro, M. W. Weiner, D. Gelinas, G. A. Dudley, and R. G. Miller. Strength, skeletal musclecomposition and enzyme activity in multiple sclerosis. J. Appl. Physiol. 83(6):1998-2004, 1997.This study examined functional, biochemical, andmorphological characteristics of skeletal muscle in nine multiplesclerosis (MS) patients and eight healthy controls in an effort toascertain whether intramuscular adaptations could account for excessivefatigue in this disease. Analyses of biopsies of the tibialis anteriormuscle showed that there were fewer type I fibers (66 ± 6 vs. 76 ± 6%), and that fibers of all types were smaller (average26%) and had lower succinic dehydrogenase (SDH; average40%) and SDH/-glycerol-phosphate dehydrogenase (GPDH) butnot GPDH activities in MS vs. control subjects, suggesting that musclein this disease is smaller and relies more on anaerobic thanaerobic-oxidative energy supply than does muscle of healthyindividuals. Maximal voluntary isometric force fordorsiflexion was associated with both average fiber cross-sectionalarea (r = 0.71, P = 0.005) and muscle fat-free cross-sectional area by magnetic resonance imaging(r = 0.80, P < 0.001). Physical activity,assessed by accelerometer, was associated with average fiber SDH/GPDH(r = 0.78, P = 0.008). There was a tendency forsymptomatic fatigue to be inversely associated with average fiber SDHactivity (r = 0.57,P = 0.068). The results of thisstudy suggest that the inherent characteristics of skeletal musclefibers per se and of skeletal muscle as a whole are altered in thedirection of disuse in MS. They also suggest that changes in skeletalmuscle in MS may significantly affect function.

     

Thermoregulatory control during pregnancy and lactation in rats

Eliason, Heather L., and James E. Fewell.Thermoregulatory control during pregnancy and lactation in rats.J. Appl. Physiol. 83(3): 837-844, 1997.Although the mechanisms remain unknown, maternal coretemperature (T_c) decreases nearterm of pregnancy and is increased throughout lactation in rats. Thepurpose of our present experiments was to determine whether pregnancy and lactation shift the thermoneutral zone of rats and to investigate whether the changes in maternal T_cduring pregnancy and lactation result from "forced" or"regulated" thermoregulatory responses. Conscious, chronicallyinstrumented nonpregnant and pregnant and lactating rats were studiedboth in a thermocline (a chamber with a linear temperature gradientfrom 12 to 36°C) and in a metabolic chamber to determine theinfluence of pregnancy and lactation on selected ambient temperature aswell as the thermoregulatory response to changes in ambienttemperature. We found that selected ambient temperature, oxygenconsumption, and thermal conductance did not change in rats studied ina thermocline as T_c decreased nearterm of pregnancy. There was, however, a downward shift in thethermoneutral zone of rats studied in a metabolic chamber near term ofpregnancy. During lactation, selected ambient temperature decreased inrats studied in a thermocline as oxygen consumption andT_c increased. The thermoneutralzone of lactating rats was not different from that of nonpregnantanimals. Thus our data provide evidence that the decrease inT_c near term of pregnancy in ratsresults from a regulated thermoregulatory response,whereas the increase in T_c duringlactation results from a forced thermoregulatory response.

     

Clinical and Molecular Characterization of Patients with Distal 11q Deletions

Jacobsen syndrome is caused by segmental aneusomy for the distal end of the long arm of chromosome 11. Typical features include mild to moderate psychomotor retardation, trigonocephaly, facial dysmorphism, cardiac defects, and thrombocytopenia, though none of these features are invariably present. To define the critical regions responsible for these abnormalities, we studied 17 individuals with de novo terminal deletions of 11q. The patients were characterized in a loss-of-heterozygosity analysis using polymorphic dinucleotide repeats. The breakpoints in the complete two-generation families were localized with an average resolution of 3.9 cM. Eight patients with the largest deletions extending from 11q23.3 to 11qter have breakpoints, between D11S924 and D11S1341. This cytogenetic region accounts for the majority of 11q⁻ patients and may be related to the FRA11B fragile site in 11q23.3. One patient with a small terminal deletion distal to D11S1351 had facial dysmorphism, cardiac defects, and thrombocytopenia, suggesting that the genes responsible for these features may lie distal to D11S1351. Twelve of 15 patients with deletion breakpoints as far distal as D11S1345 had trigonocephaly, while patients with deletions distal to D11S912 did not, suggesting that, if hemizygosity for a single gene is responsible for this dysmorphic feature, the gene may lie distal to D11S1345 and proximal to D11S912.     

Elemental signatures of human diets from the Georgia Bight

Multielement analysis was performed on bone samples extracted from the femora of 39 adults from three mortuary sites (Johns Mound, Santa Catalina de Guale, and Santa Catalina de Guale de Santa Meria) and time periods (late preagricultural, early contact, and late contact) in the Georgia Bight. This study was used to investigate whether elemental analysis would support or contradict other lines of data regarding diets and dietary change previously generated for the region. The data are in agreement with an earlier interpretation, based on stable isotopes, that dietary maize increases through time but fails to support the idea that marine resources decreased in importance. Rather, it appears that the wild plant food component of the diets decreases as maize increases in importance; throughout the sequence, marine resources comprise a significant portion of the diets. © 1995 Wiley-Liss, Inc.