Hepatic P450 Enzyme Activity, Tissue Morphology and Histology of Mink (Mustela vison) Exposed to Polychlorinated Dibenzofurans

Dose- and time-dependent effects of environmentally relevant concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQ) of 2,3,7,8-tetrachlorodibenzofuran (TCDF), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), or a mixture of these two congeners on hepatic P450 enzyme activity and tissue morphology, including jaw histology, of adult ranch mink were determined under controlled conditions. Adult female ranch mink were fed either TCDF (0.98, 3.8, or 20 ng TEQTCDF/kg bw/day) or PeCDF (0.62, 2.2, or 9.5 ng TEQPeCDF/kg bw/day), or a mixture of TCDF and PeCDF (4.1 ng TEQTCDF/kg bw/day and 2.8 ng TEQPeCDF/kg bw/day, respectively) for 180 days. Doses used in this study were approximately eight times greater than those reported in a parallel field study. Activities of the cytochrome P450 1A enzymes, ethoxyresorufin O-deethylase (EROD) and methoxyresorufin O-deethylase (MROD) were significantly greater in livers of mink exposed to TCDF, PeCDF, and a mixture of the two congeners; however, there were no significant histological or morphological effects observed. It was determined that EROD and MROD activity can be used as sensitive biomarkers of exposure to PeCDF and TCDF in adult female mink; however, under the conditions of this study, the response of EROD/MROD induction occurred at doses that were less than those required to cause histological or morphological changes

SEX-BASED ANALYSIS OF THE BIOMECHANICS OF PITCHING

Madison J. Blankenship1, Hunter L. Frisk1, Evan M. Martin1, and William P. Ebben1 1Lakeland University, Plymouth, WI Understanding pitching biomechanics and sex-based differences is necessary for training pitchers in the most sport specific method possible. PURPOSE: This study assessed sex-based differences in the propulsive and landing phase kinetics, athlete whole body velocity, and the relationship between these variables and pitched ball velocity. METHODS:15 men (age = 19.47 ± 1.18 years) and 15 women (age = 20.07 ± 2.17 years) served as subjects and provided informed written consent. The study was approved by the IRB. Subjects threw six fastballs from the wind-up. Subjects pitched from a pitching rubber bolted to the first of two force platforms, flush mounted and deployed in series. The first and second force platforms captured the propulsive and landing phases of the pitcher, respectively. Kinetic data analysis included horizontal and vertical peak ground reaction forces (GRF), the ratio of both (H:V), and the rate of force development (RFD). Ball velocity was determined by Doppler radar. Independent samples t-tests were used to assess differences in subject background, pitch velocity, propulsive and landing phase GRF, H:V, and RFD. Paired samples t-tests was used to determine differences between propulsive and landing phase GRF, H:V, and RFD. Pearson’s correlation coefficients were used to assess the relationship between the kinetic variables and ball velocity. RESULTS: Subject age, weight, and years of pitching experiences were not statistically different between men and women (p ≥ 0.05). Men were taller than women (p = 0.001). Fastball velocity was significantly greater (p = 0.001) for men (33.17 ± 2.21 m·s-1) than women (22.52 ± 1.47 m·s-1). During the propulsive phase, the H:V of men (0.37:1 ± 0.05:1) was greater (p \u3c 0.05) than women (0.32:1 ± 0.07:1). During the landing phase, women demonstrate higher (p \u3c 0.05) vertical GRF/body mass (1.91 ± 0.13 N) and RFD/body mass (23.36 ± 2.59 N·s-1) than men (1.43 ± 0.13 N) and (17.45 ± 1.53 N·s-1). There was no correlation between any biomechanical variables and ball velocity for either men or women (p ≥ 0.05). CONCLUSION: Training strategies for men should emphasize horizontal rather than vertical force production during the propulsive phase. Training strategies for women should increase their capability to manage large vertical GRF and RFD during the landing phase of pitching