Identifying HIF activity in three-dimensional cultures of islet-like clusters.

PURPOSE: Hypoxia is a major cause for failure of encapsulated islet grafts. Three-dimensional (3D) re-aggregation and hypoxic preconditioning are used to help overcome this obstacle. However, it is still difficult to identify hypoxic cells in a 3D system. We evaluate the efficacy of a fluorescent system for detecting HIF-1 activity in live ß-cells. Identification of HIF-1 activity and correlation with insulin secretion and viability will allow for more informed implant construction and better prediction of post-transplantational function.
 METHODS: MIN6 cells were infected with the marker virus and rotationally cultured to form clusters. Clusters were encapsulated in PEG hydrogels and incubated in 20%, 2%, or 1% O2. Gels were imaged daily for hypoxia marker signaling and for morphological observation. Daily GSIS was quantified by insulin ELSIA and cell viability was assessed by LIVE/DEAD staining.
 RESULTS: Clusters cultured in 2% and 1% O2 displayed high levels of HIF activity compared to 20% O2 clusters. 20% O2 clusters maintained viability and achieved a smooth, islet-like morphology by Day 14. Clusters in 2% and 1% O2 failed to associate cohesively and showed reduced viability. As a whole, constructs cultured in 20% O2 exhibited 10-fold higher GSIS than constructs in 2% and 1% O2.
 CONCLUSIONS: Our marker is an effective approach for identifying cellular hypoxia in 3D cultures. ß-cell clusters in 2% and 1% O2 are similarly affected by reduced oxygen tension, with HIF-1 activity correlating to reduced GSIS and impaired cell/cluster morphology. Simultaneous aggregative culture and hypoxic conditioning may not be beneficial to ß-cell transplantation.

The effects of 6-week training programs on throwing accuracy, proprioception, and core endurance in baseball.

CONTEXT: With a limited number of outcomes-based studies, only recommendations for strength-training and rehabilitation programs can be made. OBJECTIVE: To determine the extent to which throwing accuracy, core stability, and proprioception improved after completion of a 6-week training program that included open kinetic chain (OKC), closed kinetic chain (CKC), and/or core-stability exercises. DESIGN: A 2 x 3 factorial design. SETTING: Division III college. PARTICIPANTS: 19 healthy baseball athletes with a control group of 15. INTERVENTIONS: Two 6-week programs including OKC, CKC, and core-stabilization exercises that were progressed each week. MAIN OUTCOME MEASURES: Functional throwing-performance index, closed kinetic chain upper extremity stability test, back-extensor test, 45 degrees abdominal-fatigue test, and right- and left-side bridging test. RESULTS: There was no significant difference between groups. An increase was evident in all pretest-to-posttest results, with improvement ranging from 1.36% to 140%. CONCLUSION: Both of the 6-week training programs could be used to increase throwing accuracy, core stability, and proprioception in baseball.

The effects of a 10-week, periodized, off-season resistance-training program and creatine supplementation among collegiate football players.

The periodized resistance-training model has not been well documented in the literature. Further research is needed to determine if periodized resistance training in conjunction with creatine supplementation can cause changes in strength, performance, total body weight, girth, and lean muscle mass. Therefore, the purpose of this investigation was to determine the effects of periodized resistance training in conjunction with low-dose (LD) and high-dose (HD) creatine supplementation on strength, body composition, and anaerobic muscular endurance. Subjects were divided into 3 groups: LD, HD, and placebo (P). Testing took place pre-, mid-, and postsupplementation for the following: weight, body composition (fat-free mass and fat mass), 1 repetition maximum squat, and anaerobic muscular endurance testing. Results revealed no significant differences in either creatine group when compared with the P group. However, significant differences were noted over time. These data suggest that 10 weeks of periodized resistance training was effective for causing changes in strength, body composition, and anaerobic muscular endurance.

The Effects of Low-Dose Creatine Supplementation Versus Creatine Loading in Collegiate Football Players.

OBJECTIVE: To compare the effects of low doses of creatine and creatine loading on strength, urinary creatinine concentration, and percentage of body fat. DESIGN AND SETTING: Division IA collegiate football players took creatine monohydrate for 10 weeks during a sport-specific, periodized, off-season strength and conditioning program. One-repetition maximum (1-RM) squat, urinary creatinine concentrations, and percentage of body fat were analyzed. SUBJECTS: Twenty-five highly trained, Division IA collegiate football players with at least 1 year of college playing experience. MEASUREMENTS: We tested strength with a 1-RM squat exercise before, during, and after creatine supplementation. Percentage of body fat was measured by hydrostatic weighing before and after supplementation. Urinary creatinine concentration was measured via light spectrophotometer at 0, 1, 3, 7, 14, 21, 28, 35, 42, 48, 56, and 63 days. An analysis of variance with repeated measures was computed to compare means for all variables. RESULTS: Creatine supplementation had no significant group, time, or interaction effects on strength, urinary creatinine concentration, or percentage of body fat. However, significant time effects were found for 1-RM squat and fat-free mass in all groups. CONCLUSIONS: Our data suggest that creatine monohydrate in any amount does not have any beneficial ergogenic effects in highly trained collegiate football players. However, a proper resistance training stimulus for 10 weeks can increase strength and fat-free mass in highly trained athletes.