Exercise-induced improvements in myocardial antioxidant capacity: the antioxidant players and cardioprotection.

Endurance exercise training is known to promote beneficial adaptations to numerous tissues including the heart. Indeed, endurance exercise training results in a cardioprotective phenotype that resists injury during an ischemia-reperfusion (IR) insult. Because IR-induced cardiac injury is due, in part, to increased production of radicals and other reactive oxygen species, many studies have explored the impact of exercise training on myocardial antioxidant capacity. Unfortunately, the literature describing the effects of exercise on the cardiac antioxidant capacity is widely inconsistent. Nonetheless, a growing body of evidence indicates that regular bouts of endurance exercise promote an increase in the expression of both superoxide dismutase 1 and 2 in cardiac mitochondria. Moreover, emerging evidence suggests that exercise also increases accessory antioxidant enzymes in the heart. Importantly, robust evidence indicates that as few as five consecutive days of endurance exercise training results in a cardiac phenotype that resists IR-induced arrhythmias, myocardial stunning, and infarction. Further, mechanistic studies indicate that exercise-induced increases in mitochondrial superoxide dismutase 2 play a key role in this adaptation. Future studies are required to provide a complete picture regarding the cellular adaptations that are responsible for exercise-induced cardioprotection.

Cumulative responses of muscle protein synthesis are augmented with chronic resistance exercise training.

AIM: The purpose of this study was to determine the anabolic response of a single bout of high intensity resistance exercise (RE) following 5 weeks of RE training. METHODS: To complete these studies, Sprague-Dawley rats were assigned by body mass to RE, exercise control (EC), or sedentary cage control (CC) groups and studied over 36 h after 5 weeks of RE (squat-like) training. Cumulative (final 36 h) fractional rates of muscle protein synthesis (FSR) were determined by ²H2O, and acute (16 h post-RE) rates of muscle protein synthesis (RPS) were determined by flooding with l-[2,3,4,5,6-³H]phenylalanine. Regulators of peptide-chain initiation, 4E-BP1, eIF4E and the association of the two were determined by Western blotting and immunoprecipitation respectively. RESULTS: No differences were observed with acute measures of RPS obtained 16 h following the final exercise bout in the plantaris or soleus muscles (P > 0.05). Consistent with this observation, 4E-BP1 was similarly phosphorylated and bound to eIF4E among all groups. However, upon determination of the cumulative response, FSR was significantly increased in the plantaris of RE vs. EC and CC (0.929±0.094, 0.384±0.039, 0.300±0.022% h(-1) respectively; P<0.001), but not the soleus. CONCLUSION: With the advantage of determining cumulative FSR, the present study demonstrates that anabolic responses to RE are still evident after chronic RE training, primarily in muscle composed of fast-twitch fibres.

Increased training loads do not magnify cancellous bone gains with rodent jump resistance exercise.

This study sought to elucidate the effects of a low- and high-load jump resistance exercise (RE) training protocol on cancellous bone of the proximal tibia metaphysis (PTM) and femoral neck (FN). Sprague-Dawley rats (male, 6 mo old) were randomly assigned to high-load RE (HRE; n = 16), low-load RE (LRE; n = 15), or sedentary cage control (CC; n = 11) groups. Animals in the HRE and LRE groups performed 15 sessions of jump RE during 5 wk of training. PTM cancellous volumetric bone mineral density (vBMD), assessed by in vivo peripheral quantitative computed tomography scans, significantly increased in both exercise groups (+9%; P < 0.001), resulting in part from 130% (HRE; P = 0.003) and 213% (LRE; P < 0.0001) greater bone formation (measured by standard histomorphometry) vs. CC. Additionally, mineralizing surface (%MS/BS) and mineral apposition rate were higher (50-90%) in HRE and LRE animals compared with controls. PTM bone microarchitecture was enhanced with LRE, resulting in greater trabecular thickness (P = 0.03) and bone volume fraction (BV/TV; P = 0.04) vs. CC. Resorption surface was reduced by nearly 50% in both exercise paradigms. Increased PTM bone mass in the LRE group translated into a 161% greater elastic modulus (P = 0.04) vs. CC. LRE and HRE increased FN vBMD (10%; P < 0.0001) and bone mineral content (∼ 20%; P < 0.0001) and resulted in significantly greater FN strength vs. CC. For the vast majority of variables, there was no difference in the cancellous bone response between the two exercise groups, although LRE resulted in significantly greater body mass accrual and bone formation response. These results suggest that jumping at minimal resistance provides a similar anabolic stimulus to cancellous bone as jumping at loads exceeding body mass.

Comparison of velopharyngeal gap size in patients with hypernasality, hypernasality and nasal emission, or nasal turbulence (rustle) as the primary speech characteristic.

Velopharyngeal insufficiency was assessed using multiview videofluoroscopy on eight patients with hypernasality, 10 patients with hypernasality and audible nasal emission, and 10 patients with nasal turbulence (rustle). Patients demonstrating hypernasality, with or without audible nasal emission, were found to have a significantly larger velopharyngeal gap than those with nasal rustle. This finding suggests that the degree of the velopharyngeal insufficiency can be predicted to some extent based on perceptual assessment. If the presence of a nasal rustle suggests a small velopharyngeal gap, despite the severe distortion of speech, then speech therapy should be considered prior to surgery in those cases.

Sequence and organization of 5S RNA genes from the eukaryotic protist Acanthamoeba castellanii.

A 5S RNA genomic clone has been isolated from Acanthamoeba castellanii and the sequence of the coding region plus flanking DNA was determined. This clone encodes an RNA whose sequence matches that of 5S RNA from this organism. There is sequence similarity in the 5'-flanking region to other eukaryotic 5S RNA genes which require or are greatly affected by upstream regions for transcriptional activity. The immediate 3'-flanking region has a termination sequence similar to that found in all genes that are transcribed by RNA polymerase III. The 5S RNA genes of A. castellanii are dispersed, which is highly unusual, since the majority of eukaryotic organisms contain 5S genes clustered in tandem repeats. There may be up to 480 genes encoding 5S RNA in each A. castellanii cell.

STA10: A gene involved in the control of starch utilization by Saccharomyces.

Genetic analysis of crosses carried out between starch utilizing strains of Saccharomyces diastaticus and laboratory strains of S. cerevisiae has revealed the existence of a gene which inhibits the expression of the amylolytic capability in the resulting hybrids, as well as in the meiotic offspring of the crosses. This gene is unlinked to any of the three STA genes which are known to be responsible for starch utilization by S. diastaticus.