Bone mineral density in elite junior Olympic weightlifters

The purpose of this study was to examine the relationship of bone mineral density (BMD) to muscular strength in highly trained young male athletes in order to gain insights concerning the influence of heavy resistance training on BMD. Twenty-five elite junior weightlifters (age, 17.4 +/- 1.4 yr) and 11 age-matched controls (16.9 +/- 1.1 yr) volunteered for this investigation. Measurements of BMD (g.cm-2) utilizing dual energy x-ray absorptiometry were obtained for the lumbar spine (L2-4) and the proximal femur (neck; trochanter, Ward's triangle). The BMD values for the junior lifters were found to be significantly greater at all sites for the junior weightlifters compared with their age-matched control group. The BMD values of the spine and femoral neck of the junior weightlifters when compared with adult reference data (i.e., 20-39 yr old men) were found to be significantly greater. Both simple and multiple regression analyses demonstrated significant relationships of BMD with strength accounting for 30-65% of the variance. These data suggest that in elite junior weightlifters, muscle strength, highly specific to the sport of weightlifting, has a major influence on BMD due to the influence of the chronic overloads experienced in training.     

Combined enzyme and antimicrobial susceptibility profiles of caprine Pasteurella haemolytica serovar 2 respiratory tract isolates

The present investigation describes a novel method of demonstrating strain diversity among Pasteurella haemolytica biovar A, serovar 2 (PhA2) nasal turbinate isolates from a flock of 32 experimental goats during a naturally occurring outbreak of pasteurellosis. After a 21 day conditioning period in a feedyard, 51 PhA2 isolates from 27 culture-positive goats were identified including 1 on day 22, 14 on day 25, 21 on day 39, and 15 on day 66. Each PhA2 isolate was evaluated for its enzyme activity against 19 substrates with a commercial semiquantitative enzyme system and for its antimicrobial susceptibility with 12 drugs, resulting in 7 different enzyme profiles and 8 different antimicrobial susceptibility profiles. A total of 14 combined enzyme and antimicrobial susceptibility profiles were produced. The same PhA2 strain was isolated from only 4 of the 12 goats with 2 PhA2 isolations, while the same PhA2 strain was isolated from only 1 of the 6 goats with 3 PhA2 isolations. The data from this investigation demonstrated that the PhA2 upper respiratory tract flora from goats is highly heterologous.     

Eating, weight, and dieting disturbances in male and female lightweight and heavyweight rowers

Rowers compete in a sport that allows comparison of male and female athletes and where some (lightweight) but not others (heavyweights) must meet specific weight criteria. Eating attitudes, dieting patterns, weight fluctuation, and methods of weight loss were evaluated in 162 rowers: 82 heavyweights (56 females, 26 males) and 80 lightweights (17 females, 63 males). Females displayed more disturbed eating practices and weight control methods than did males. Lightweights did not have more disturbed eating practices than heavyweights, but employed more extreme weight loss methods. Male rowers were more affected by weight restriction than were female rowers. Lightweight males showed greater weight fluctuation during the season and gained more weight during the offseason than did lightweight females and heavyweight males and females. These results indicate that rowing can join the growing list of sports where eating and weight disturbances may be present. Male athletes may be more vulnerable to these problems than previously recognized.     

Kinetic characterization of human immunodeficiency virus type-1 protease-resistant variants

Passage of human immunodeficiency virus type-1 (HIV-1) in T-lymphocyte cell lines in the presence of increasing concentrations of the hydroxylethylamino sulfonamide inhibitor VX-478 or VB-11328 results in sequential accumulation of mutations in HIV-1 protease. We have characterized recombinant HIV-1 proteases that contain these mutations either individually (L10F, M46I, I47V, I50V) or in combination (the double mutant L10F/I50V and the triple mutant M46I/I47V/I50V). The catalytic properties and affinities for sulfonamide inhibitors and other classes of inhibitors were determined. For the I50V mutant, the efficiency (kcat/Km) of processing peptides designed to mimic cleavage junctions in the HIV-1 gag-pol polypeptide was decreased up to 25-fold. The triple mutant had a 2-fold higher processing efficiency than the I50V single mutant for peptide substrates with Phe/Pro and Tyr/Pro cleavage sites, suggesting that the M46I and I47V mutations are compensatory. The effects of mutation on processing efficiency were used in conjunction with the inhibition constant (Ki) to evaluate the advantage of the mutation for viral replication in the presence of drug. These analyses support the virological observation that the addition of M46I and I47V mutations on the I50V mutant background enables increased survival of the HIV-1 virus as it replicates in the presence of VX-478. Crystal structures and molecular models of the active site of the HIV-1 protease mutants suggest that changes in the active site can selectively affect the binding energy of inhibitors with little corresponding change in substrate binding.     

Oesophagostomum spp. in pigs: resistance to reinfection

For a study on the occurrence of resistance to reinfection with porcine nodular worm species, pigs were infected twice weekly with 1,000 infective larvae (L3) of Oesophagostomum quadrispinulatum for 8 weeks. All pigs, including noninfected controls, were then treated with fenbendazole. At 10 days after treatment, all pigs received a single challenge inoculation of 5,000 L3 of either O. dentatum or O. quadrispinulatum, respectively. Pigs were slaughtered at 6 weeks after the challenge infection for determination of their worm burdens. The pigs trickle- and challenge-infected with O. quadrispinulatum had significantly lower egg excretion levels (P < 0.01) and worm burdens (P < 0.05) than challenge control pigs, thus indicating some degree of host immunity against the homologous challenge infection. No resistance to reinfection was evident for the heterologous challenge infection. This study elucidates further aspects of the interaction between nodular worm species in the pig.     

5-Benzylidene 1,2-dihydrochromeno[3,4-f]quinolines, a novel class of nonsteroidal human progesterone receptor agonists

A novel series of nonsteroidal progestins, 5-benzylidene-1, 2-dihydrochromeno[3,4-f]quinolines (2), was discovered, and a preliminary structure-activity relationship study around the 5-benzylidene ring generated several potent human progesterone receptor agonists (compounds 8, 16). These new progestins showed biological activities (EC50 = 5.7 and 7.6 nM) similar to progesterone (EC50 = 2.9 nM) in the cotransfection assay with high efficacy (132% and 166%) and binding affinity (Ki = 0.66 and 0.83 nM) similar to medroxyprogesterone acetate (MPA) (Ki = 0.34 nM). A representative analogue, 8, demonstrated similar oral potency to MPA in the uterine wet weight/mammary gland morphology assay in ovariectomized rats.