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AIM: Short-term exercise training may induce metabolic and performance adaptations before any changes in mitochondrial enzyme potential. However, there has not been a study that has directly assessed changes in mitochondrial oxidative capacity or metabolic control as a consequence of such training in vivo. Therefore, we used (31) P-magnetic resonance spectroscopy ((31) P-MRS) to examine the effect of short-term plantar flexion exercise training on phosphocreatine (PCr) recovery kinetics and the control of respiration rate. METHOD: To this aim, we investigated 12 healthy men, experienced with this exercise modality (TRA), and 7 time-control subjects (TC). RESULTS: After 5 days of training, maximum work rate during incremental plantar flexion exercise was significantly improved (P < 0.01). During the recovery period, the maximal rate of oxidative adenosine triphosphate synthesis (PRE: 28 ± 13 mm min(-1) ; POST: 26 ± 15 mm min(-1) ) and the PCr recovery time constant (PRE: 31 ± 19 s; POST: 29 ± 16) were not significantly altered. In contrast, the Hill coefficient (nH ) describing the co-operativity between respiration rate and ADP was significantly increased in TRA (PRE: nH = 2.7 ± 1.4; POST: nH = 3.4 ± 1.9, P < 0.05). Meanwhile, there were no systematic variations in any of these variables in TC. CONCLUSION: This study reveals that 5 days of training induces rapid adaptation in the allosteric control of respiration rate by ADP before any substantial improvement in muscle oxidative capacity occurs.

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The goal of this investigation was to characterize the commercially available fan unit for the KreitlerAlloy rollers at submaximal levels of effort (< or = 500 W). A single cyclist rode six times at each of three fan inlet settings (closed, half, and full open) and five fan speeds (900, 1800, 2700, 3600, and 4500 rpm). Fan power requirements were isolated by subtracting roller resistance from separate trials. Power requirements relative to fan inlet and fan speed possessed a significant interaction with the main effects for each also significant (all p < 0.001). Power increased to the cube of fan speed, regardless of inlet opening (r2 > or = 0.997). Fan resistance was virtually non existent at 900 rpm. Fan resistance then significantly increased with increasing fan speed and inlet opening. At 4500 rpm power requirements of the fan reached 269 +/- 6, 352 +/- 7, and 406 +/- 9 W with the inlet closed, half, and fully open, respectively (p < 0.001). The rear wheel-roller interaction supplied an additional 19 +/- 2 W on up to 104 +/- 4 W at the highest speed. Therefore, the fan unit increases the functionality of the rollers for a variety of training and testing environments.

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OBJECTIVE: To document the chiropractic management of a patient who sustained a Chance fracture of the third lumbar vertebra. This case study represents the first report in the scientific literature of such an injury managed through chiropractic methods. CLINICAL FEATURES: An 18-yr-old man complained of low back pain and paresthesia in the lower extremities 10 days after suffering an automobile accident. Examination revealed a large circular edematous area from L1 to L4, tenderness to palpation at the L3 spinous process, reduction in global range of motion at the thoracolumbar region, and positive Lasègue and Kemp tests (bilaterally). Radiographic and computed tomographic scans revealed a Chance fracture of the L3 vertebra. INTERVENTION AND OUTCOME: The patient received specific-contact, short-lever arm spinal adjustments delivered primarily at L3 and L5, as well as bracing. Four months after initial treatment, the patient's complaint of paresthesia had resolved and he suffered only occasional minor low back pain. The comparative radiographs demonstrate a reduction in the separation of the fracture fragments. CONCLUSION: A case report is presented of a patient who suffered a Chance fracture of L3. The patient was eventually managed by chiropractic methods including a specific contact high-velocity thrust procedure administered at the level of the fractured vertebra. The case represents the first known reporting of this type of chiropractic procedure applied to a patient with a Chance fracture.

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Functional transcription elongation complexes can be formed by adding RNA polymerase in trans to a preformed nucleic acid construct. This construct consists of a double-stranded DNA fragment that contains a noncomplementary (permanent DNA bubble) region into which an RNA primer oligonucleotide has been hybridized. By ligating a DNA fragment containing the strong intrinsic terminator T7Te to the RNA.DNA bubble duplex, we show here that Escherichia coli core RNA polymerase-catalyzed transcription, initiated from such a construct, terminates at the predicted position. Furthermore, we show that the termination efficiency obtained is comparable to that observed in a control reaction initiated with the E. coli holopolymerase from the T7A1 promoter if an RNA oligomer trap is used to permit proper displacement of the nascent RNA from the DNA template strand. The trap oligomer is complementary to the template strand of the permanent DNA bubble and prevents rehybridization of the nascent RNA at this site. Varying the amount of RNA trap that is added permits us to modulate the extent of total RNA displacement. Our results show that RNA displacement and termination efficiency are directly correlated, suggesting that intrinsic termination requires that the nascent RNA be free to assume its solution conformation. Several models of intrinsic termination are presented and discussed in light of these data.

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