The impact of metabolic stress on hormonal responses and muscular adaptations

PURPOSE: The purpose of this study was to examine the impact of exercise-induced metabolic stress on hormonal responses and chronic muscular adaptations. METHODS: We compared the acute and long-term effects of an "NR regimen" (no-rest regimen) and those of a "WR regimen" (regimen with rest period within a set). Twenty-six male subjects were assigned to either the NR (N = 9), WR (N = 9), or control (CON, N = 8) groups. The NR regimen consisted of 3-5 sets of 10 repetitions at 10-repetition maximum (RM) with an interset rest period of 1 min (lat pulldown, shoulder press, and bilateral knee extension). In the WR regimen, subjects completed the same protocol as the NR regimen, but took a 30-s rest period at the midpoint of each set of exercises in order to reduce exercise-induced metabolic stress. Acute hormonal responses to both regimens were measured followed by a 12-wk period of resistance training. RESULTS: Measurements of blood lactate and serum hormone concentrations after the NR and WR regimens showed that the NR regimen induced strong lactate, growth hormone (GH), epinephrine (E), and norepinephrine (NE) responses, whereas the WR regimen did not. Both regimens failed to cause significant changes in testosterone. After 12 wk of resistance training, the NR regimen caused greater increases in 1RM (P < 0.01), maximal isometric strength (P < 0.05), and muscular endurance (P < 0.05) with knee extension than the WR regimen. The NR group showed a marked increase (P < 0.01) in muscle cross-sectional area, whereas the WR and CON groups did not. CONCLUSION: These results suggest that exercise-induced metabolic stress is associated with acute GH, E, and NE responses and chronic muscular adaptations following resistance training.     

Reductions in basal limb blood flow and lumen diameter after short-term leg casting

PURPOSE: We tested the hypotheses that short-term casting immobilization of a leg would reduce basal blood flow and vascular conductance and induces structural alterations in femoral artery. METHODS: Right knee and ankle joints of eight healthy young men were immobilized with casting for 7 d. Before and immediately after casting, and 14 d after the cast was removed, femoral artery hemodynamics and structure were measured using a high-resolution ultrasound. RESULTS: Femoral artery lumen diameter in the immobilized leg decreased after the immobilization (P < 0.05) and returned to baseline during the recovery period, in which the subjects did not receive any special rehabilitation treatment. Femoral artery intima-media thickness (IMT) and IMT/lumen ratio in both legs did not show significant changes throughout the interventions. In the immobilized leg, femoral artery blood flow and vascular conductance decreased (-23 to 24%) after the immobilization (all P < 0.05). These parameters returned to the baseline during the recovery period, and there were no significant differences between the baseline and recovery values. In the control leg, femoral blood flow and vascular conductance did not change throughout the investigation. After 7 d of casting, femoral arterial distension, an index of arterial distensibility, tended to decrease in the immobilized leg but not in the control leg. CONCLUSION: We concluded that a short-term immobilization of lower limb decreases basal limb blood flow and arterial lumen diameter. These results suggest that basal limb blood flow and lumen diameter decrease rapidly upon the cessation of muscular weight bearing and locomotor activity, and may be modulated by an ordinary level of physical activity.     

Studies on novel bacterial translocase I inhibitors,A-500359s. I. Taxonomy,fermentation, isolation,physico-chemical properties and structure elucidation of A-500359 A,C, D and G

In the course of our screening for bacterial phospho-N-acetylmuramyl-pentapeptide-translocase (translocase I: EC 2.7.8.13) inhibitors, we found inhibitory activity in the cultured broth of the strain identified as Streptomyces griseus SANK 60196. The strain produced capuramycin and four novel capuramycin derivatives designated as A-500359 A, C, D and G. Purification and structural analysis were performed, and the structures of A-500359 A, C, D and G were elucidated as 6'-methylcapuramycin, 3'-demethyl-6'-methylcapuramycin, 2'-deoxy-6'-methylcapuramycin and 3'-demethylcapuramycin, respectively.     

N-[11C-Methyl]chlorphentermine and N,N-[11C-dimethyl]chlorphentermine as brain blood-flow agents for positron emission tomography

N-[11C-methyl]chlorphentermine ([11C]NMCP) and N,N-[11C-dimethyl]chlorphentermine ([11C]NDMCP) were prepared from chlorphentermine and 11CH3I in DMF and evaluated in rats as brain blood-flow agents for positron emission tomography (PET). Tissue distribution of [11C]NMCP showed that brain uptake was 2.70 +/- 0.40% of injected dose per organ at 5 min with no change in radioactivity concentration up to 30 min after i.v. injection. Approximately 80% of the initial brain uptake remained at 60 min. On the other hand, initial brain uptake of [11C] NDMCP (3.66 +/- 0.31 and 3.63 +/- 0.88% injected dose per organ at 5 and 15 min, respectively) was greater than that of [11C]NMCP. The brain activity however, rapidly decreased to 2.38 +/- 0.17 and 1.82 +/- 0.32% at 30 and 60 min, respectively. Because of its longer retention in the brain compared with [11C]NDMCP, [11C]NMCP would be a potential brain blood-flow agent for quantitative PET studies.     

Protective role of melatonin in progesterone production by human luteal cells

This study investigated whether melatonin protects luteinized granulosa cells from reactive oxygen species (ROS) as an antioxidant to enhance progesterone production in the follicle during ovulation. Follicular fluid was sampled at the time of oocyte retrieval in women undergoing in vitro fertilization and embryo transfer (IVF-ET). Melatonin concentrations in the follicular fluid were positively correlated with progesterone concentrations (r = 0.342, P < 0.05) and negatively correlated with the concentration of 8-hydroxy-2'-deoxyguanosine (8-OHdG), an oxidative stress marker (r = -0.342, P < 0.05). The progesterone and 8-OHdG concentrations were negatively correlated (r = -0.246, P < 0.05). Luteinized granulosa cells were obtained at the time of oocyte retrieval in women undergoing IVF-ET. Cells were incubated with H(2)O(2) (30, 50, 100 μm) in the presence or absence of melatonin (1, 10, 100 μg/mL). Progesterone production by luteinized granulosa cells was significantly inhibited by H(2)O(2). Melatonin treatment overcame the inhibitory effect of H(2) O(2) . Twenty-five patients who had luteal phase defect (serum progesterone concentrations <10 ng/mL during the mid-luteal phase) were divided into two groups during the next treatment cycle: 14 women were given melatonin (3 mg/day at 22:00 hr) throughout the luteal phase and 11 women were given no medication as a control. Melatonin treatment improved serum progesterone concentrations (>10 ng/mL during the mid-luteal phase) in nine of 14 women (64.3%), whereas only two of 11 women (18.1%) showed normal serum progesterone levels in the control group. In conclusion, melatonin protects granulosa cells undergoing luteinization from ROS in the follicle and contributes to luteinization for progesterone production during ovulation.     

Automatic and imperative motor activations in stimulus–response compatibility: magnetoencephalographic analysis of upper and lower limbs

The stimulus–response (S–R) compatibility effect refers to the difference in performance due to the spatial S–R relationship in choice reaction time. We investigated the mechanism of neural activities in S–R compatibility at the level of the primary motor cortices for upper and lower limbs responses using magnetoencephalography (MEG). In the S–R compatible task, subjects were required to respond on the same side of the stimulus light using either an upper or lower limb. In the incompatible task, subjects were required to respond in the reverse manner. Premotor times of upper and lower limbs were faster for the compatible response than for the incompatible response. The neuromagnetic brain activities related to response execution were estimated using a multi-dipole model. Stimulus-locked MEG indicated that the current moments of motor dipoles for both effectors occurred bilaterally and reached the first peak at a constant delay irrespective of whether the task was compatible or incompatible. This indicates that the neural activation of the primary motor cortex is automatically synchronized with the stimulus onset. Response-locked MEG showed that the peak current moment of the motor dipole contralateral to the response was stronger for the compatible task than for the incompatible one regardless of whether the responses were made using the upper or lower limbs. The MEG results suggest that automatic motor activation facilitates imperative motor activation for a compatible response, whereas it is not sufficient to prime imperative motor activation for an incompatible response.     

A-503083 A, B, E and F, novel inhibitors of bacterial translocase I, produced by Streptomyces sp. SANK 62799

Novel nucleoside antibiotics were isolated from the cultured broth of the strain classified as Streptomyces sp. SANK 62799. The strain produced four novel capuramycin derivatives designated as A-503083 A, B, E and F. Their structures were elucidated as 2'-O-carbamoyl derivatives of A-500359 A, B (capuramycin), E and F, respectively. A-503083 A, B, E and F inhibited bacterial phospho-N-acetylmuramyl-pentapeptide-translocase (translocase I: EC 2.7.8.13) with IC50 values of 0.024, 0.038, 0.135 and 17.9 microM, respectively.     

Automatic activation in the human primary motor cortex synchronized with movement preparation.

The human primary motor cortex during a unilateral finger reactive movement to visual stimuli was examined by magnetoencephalography (MEG) measurement. The brain activity related to movement execution (the motor activity contralateral to the movement side) was estimated based on movement onset conditions and reaction times. The movement onset conditions were: (1) a simple reaction time task with a visual stimulus, (2) a Go/NoGo task with different colored stimuli and (3) a Go/NoGo task with different position stimuli. Dipole source estimation was done, and the time course of the motor activity was calculated. The results showed that not only the visual response but also the contralateral motor activity was evoked by the stimulus in all cases, and even when the NoGo stimulus was given. The motor activity in the primary motor cortex was conjectured to consist of two dominant components: the first component for the movement preparation and the second component for the movement execution. Because the first component happened with a constant delay time from the stimulus even in the NoGo case, the first component, coming through a fast pathway for signals from visual stimulus processing to the motor cortex without any intervening cognitive processing, was conjectured to make the motor cortex prepare for the forthcoming movement onset automatically regardless of the stimulus instruction.     

Platelet MAO activity and the dexamethasone suppression test in depressed patients

Platelet monoamine oxidase (MAO) activity and postdexamethasone cortisol levels were determined in 26 depressed patients. The incidence of cortisol nonsuppression and the mean postdexamethasone cortisol levels were significantly higher in patients with high MAO activity than in those with low MAO activity.     

Preparation and evaluation of 3-[125I]iodo-4-aminophentermine as a brain perfusion imaging agent. Comparison with labeled phentermine derivatives

A radioiodinated derivative of the anorexinergic drug phentermine was synthesized and evaluated as a potential brain imaging agent. Stoichiometric iodination of the intermediate 4-aminophentermine (AmP) gave a mixture of mono and diiodo products, while the radioiodination at the no-carrier-added (NCA) level gave 73% isolated yield of the 3-[125I]iodo-4-aminophentermine with less than 2% of the diiodo derivative. The tissue distribution of the radiochemical in rats showed that it was readily extracted by the brain followed by relatively slow clearance from that organ. However, a comparison with other labeled phentermine derivatives indicated that the total brain uptake, retention and selectivity of the new agent were poorer, probably as a result of the presence of the 4-amino substituent.