Search

The primary motor cortex (M1) is crucial for motor learning; however, its interaction with other brain areas during motor learning remains unclear. We hypothesized that the fronto-parietal execution network (FPN) provides learning-related information critical for the flexible cognitive control that is required for practice. We assessed network-level changes during sequential finger tapping learning under speed pressure by combining magnetic resonance spectroscopy and task and resting-state functional magnetic resonance imaging. There was a motor learning-related increase in preparatory activity in the fronto-parietal regions, including the right M1, overlapping the FPN and sensorimotor network (SMN). Learning-related increases in M1-seeded functional connectivity with the FPN, but not the SMN, were associated with decreased GABA/glutamate ratio in the M1, which were more prominent in the parietal than the frontal region. A decrease in the GABA/glutamate ratio in the right M1 was positively correlated with improvements in task performance (p = 0.042). Our findings indicate that motor learning driven by cognitive control is associated with local variations in the GABA/glutamate ratio in the M1 that reflects remote connectivity with the FPN, representing network-level motor sequence learning formations. [ABSTRACT FROM AUTHOR]

Professional boxers train to reduce their body mass before a match to refine their body movements. To test the hypothesis that the well-defined movements of boxers are represented within the motor loop (cortico-striatal circuit), we first elucidated the brain structure and functional connectivity specific to boxers and then investigated plasticity in relation to boxing matches. We recruited 21 male boxers 1 month before a match (Time1) and compared them to 22 age-, sex-, and body mass index (BMI)-matched controls. Boxers were longitudinally followed up within 1 week prior to the match (Time2) and 1 month after the match (Time3). The BMIs of boxers significantly decreased at Time2 compared with those at Time1 and Time3. Compared to controls, boxers presented significantly higher gray matter volume in the left putamen, a critical region representing motor skill training. Boxers presented significantly higher functional connectivity than controls between the left primary motor cortex (M1) and left putamen, which is an essential region for establishing well-defined movements. Boxers also showed significantly higher structural connectivity in the same region within the motor loop from Time1 to Time2 than during other periods, which may represent the refined movements of their body induced by training for the match. [ABSTRACT FROM AUTHOR]

State self-esteem, the momentary feeling of self-worth, functions as a sociometer involved in maintenance of interpersonal relations. How others’ appraisal is subjectively interpreted to change state self-esteem is unknown, and the neural underpinnings of this process remain to be elucidated. We hypothesized that changes in state self-esteem are represented by the mentalizing network, which is modulated by interactions with regions involved in the subjective interpretation of others’ appraisal. To test this hypothesis, we conducted task-based and resting-state fMRI. Participants were repeatedly presented with their reputations, and then rated their pleasantness and reported their state self-esteem. To evaluate the individual sensitivity of the change in state self-esteem based on pleasantness (i.e., the subjective interpretation of reputation), we calculated evaluation sensitivity as the rate of change in state self-esteem per unit pleasantness. Evaluation sensitivity varied across participants, and was positively correlated with precuneus activity evoked by reputation rating. Resting-state fMRI revealed that evaluation sensitivity was positively correlated with functional connectivity of the precuneus with areas activated by negative reputation, but negatively correlated with areas activated by positive reputation. Thus, the precuneus, as the part of the mentalizing system, serves as a gateway for translating the subjective interpretation of reputation into state self-esteem. [ABSTRACT FROM AUTHOR]

Background:Cancer cells utilise the glycolytic pathway even when adequate oxygen is present, a phenomenon known as the Warburg effect. We examined whether this system is operative in multiple myeloma (MM) cells and whether glycolysis inhibition is a potential therapeutic modality.Methods:The MM cells were purified from 59 patients using CD138-immunomagnetic beads. The expression levels of genes associated with glycolysis, c-MYC, GLUT1, LDHA, HIF1A and pyruvate dehydrogenase kinase-1 (PDK1) were determined by real-time PCR. Glucose consumption and lactate production by MM cell lines were analysed. Oxamate, an LDH inhibitor, and dichloroacetate (DCA), a PDK1 inhibitor, were employed. Inhibition of PDK1 expression was achieved using a siRNA.Results:High LDHA expression was found to be an indicator of poor prognosis. It was also positively correlated with the expression of PDK1, c-MYC and GLUT1. Greater glucose consumption and lactate production in MM cells was associated with higher LDHA expression. All the glycolysis inhibitors (oxamate, DCA and PDK1 siRNA) induced apoptosis in MM cells. DCA combined with bortezomib showed additive cytotoxic effects.Conclusion:The present data suggest that the Warburg effect is operative in MM cells. As PDK1 is not overexpressed in normal tissues, PDK1 inhibition could serve as a novel therapeutic approach. [ABSTRACT FROM AUTHOR]

We introduce the status of the 300 MeV electron linear accelerator used for radioanalytical studies at Tohoku University. In the accelerator facility, several scientific programs for producing radioactivity have been performed in several fields, such as photon-activation analysis, nuclear chemistry, hot-atom chemistry, and radioactive tracers for material science. First, we introduce an outline of the facility and the irradiation system for producing radioactivity. Then, several topics in these fields are explored in detail. [ABSTRACT FROM AUTHOR]

In order to achieve a progressive experimental program, a new system for radioisotope production has been developed at one of the beam-courses of a multipurpose Cyclotron of K = 110 MeV. The upgraded beam-course is useful for the study of the nuclear physics and chemistry of heavy elements, radiopharmaceutical studies, the production of radioactive tracers, activation analysis using charged particles, etc. Several topics are demonstrated in the field of radioanalytical and nuclear studies. [ABSTRACT FROM AUTHOR]

We have studied the photon activation analysis of carbon in InF3-based fluoride, chalcogenide and tellurite glasses for fiber amplifiers, and especially the nuclear interference from a matrix produced by (γ,n), (γ,2n), (γ,p) and (n,γ) reactions and a flow method for the rapid and simple separation of 11C. A chemical separation technique is indispensable for determining carbon, because seventeen radionuclides are observed in these glasses. The flow method can sequentially be undertaken, the fusion of an irradiated sample with an oxidizer, the conversion of 11C into 11CO2, and the absorption of 11C in ethanolamine solution. We used a mixture of Pb3O4 and B2O3 as the oxidizer. There is interference with the 11C measurement because 18F and 68Ga are produced in fluoride and chalcogenide glasses by the 19F(γ,n), 23Na(γ,αn) and 69Ga(γ,n) reactions, respectively, and also absorbed in ethanolamine solution. Therefore, this flow method can only be applied to tellurite glasses. The chemical yield provided by the flow method was close to 100% when determining carbon in Japanese Iron and Steel Certified Reference Materials (JSS) by using lithium carbonate as a standard sample. We determined that the carbon concentrations in four kinds of tellurite glass were 7 to 14 ppm. [ABSTRACT FROM AUTHOR]

Objective: Osteoporosis is generally known to be one of the most serious adverse effects of long-term corticosteroid administration. Recently it was discovered that corticosteroid-induced osteoporosis occurs not only in trabecular bone but also in cortical bone, leading to a reduction in cortical bone strength. To ameliorate corticosteroid-induced bone injury, we administered etidronic acid plus alfacalcidol to five steroid-dependent asthmatics for 4 years and monitored therapeutic responses in trabecular bone and cortical bone using peripheral quantitative computed tomography (pQCT). Patients and interventions: The five steroid-dependent asthmatic patients included two males and three females, with a mean age 68.2 years, taking a mean daily dose of oral prednisolone of 7 mg/day. Etidronic acid 200 mg/day was administered for 14 consecutive days every 4 months for 4 years, while alfacalcidol 0.5μg was administered daily for 4 years. Main outcome measures and results: Every 4 months, the number of vertebral fractures was assessed by lateral vertebral radiographs, and the total radial bone mineral density (BMD), trabecular BMD, cortical BMD, Relative Cortical Volume (RCV) and Strength Strain Index (SSI) were assessed by pQCT (Stratec XCT-960). At follow-up, no new fractures had occurred, the trabecular BMD was found to be slightly increased (from 117.2 mg/cm at baseline to 121.6 mg/cm after 48 months), and no significant decreases were observed in the total BMD, cortical BMD, RCV or SSI. Conclusion: Based on these findings, etidronic acid plus alfacalcidol seems to be effective in preventing steroid-induced bone injury, not only in terms of trabecular and cortical BMD, but also in terms of cortical bone volume and strength, which may lead to a decrease in non-vertebral fractures. However, further investigation is required with a larger sample size and a longer administration period to confirm these findings. [ABSTRACT FROM AUTHOR]

The alpha-decay of a low energy isomer of 229Th at about 3.5 eV was sought by producing it through the (g,n) reaction on a 230Th target. Thorium isotopes in the reaction products were isolated and purified by anion exchange chromatography in a concentrated nitric acid medium to remove lanthanides fission products. The thorium fraction was further purified by samarium fluoride coprecipitation and the precipitate was mounted as a source for a-spectroscopy. Decaying a-signals were observed in the energy region that was expected for 229mTh, i.e., between 4.83 and 5.08 MeV. The half-life of the decaying component was determined from repeated experiments to be 13.9±3 hours. [ABSTRACT FROM AUTHOR]

A series of N-acetyl- L-glutamic acid oligopeptide benzyl esters with exact residue numbers 4, 6, and 12 has been synthesized by a stepwise procedure. For these oligopeptide–dioxane binary systems, the behavior of the liquid-crystalline phases has been examined␣by the use of 2H NMR, and the results indicate that highly ordered aggregates formed by these oligopeptides in dioxane are in an alignment similar to that in a nematic mesophase. [ABSTRACT FROM AUTHOR]

Yields of protons emitted in the D+D reaction in Pd, Au/Pd/PdO, Ti, and Au foils are measured by a dE–E counter telescope for bombarding energies between 2.5 and 10 keV. The experimental yields are compared with those predicted from a parametrization of the cross section and stopping power at higher energies. It is found that for Ti and Au target the enhancement of the D(d,p)T reaction is similar to that observed with a deuterium gas target (several tens of eV). The dependence of the yields on the bombarding energy corresponds well to the screening potential parameters U[sub s]=250±15 eV for Pd and 601±23 eV for Au/Pd/PdO. Possible models of the enhancement obtained are discussed. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Bremsstrahlung photons associated with the α-decay of210Po were measured in α-γ coincidence measurements with Si and Ge detectors. Emission probabilities of the bremsstrahlung deduced for210Po were 10−11∼10−12/keV/sr/decay for 100≤ Eγ≤600 keV. It was found that the bremsstrahlung yields are much smaller than those predicted by a Coulomb acceleration model. This suggests that α-particles also emit photons inside the barrier. The bremsstrahlung spectrum was compared with a quasi-classical calculation in which the bremsstrahlung emission in tunneling motion of α-particles is taken into account. It is shown that the data can be interpreted as a consequence of destructive interference of radiative amplitudes outside the Coulomb barrier with those in tunneling. [ABSTRACT FROM AUTHOR]

We examined the affinity of YM022, a potent and selective gastrin/CCK-B receptor antagonist, for canine gastrin/CCK-B and CCK-A receptors and the effects of YM022 on secretagogue- and peptone meal-induced acid secretion in the denervated, surgically separated (Heidenhain) canine gastric pouch model in comparison with those of famotidine, an H2-receptor antagonist, and atropine. YM022 inhibited the binding of [(125)I]CCK-8 and [(3)H]devazepide to canine gastrin/CCK-B and CCK-A receptors, with IC50 values of 0.73 and 136 nM, respectively. Intravenous YM022 dose-dependently inhibited pentagastrin- and peptone meal-induced acid secretion with ED50 values of 0.0261 and 0.0654 micromol/kg, respectively, without affecting histamine- or methacholine-induced acid secretion. Famotidine inhibited acid secretion induced by all stimulants, while atropine inhibited the acid secretion induced by every stimulant except histamine. These results indicated that YM022 is a highly potent and selective antagonist for the canine gastrin/CCK-B receptor and suppressed pentagastrin- and peptone meal-induced gastric acid secretion without affecting histamine- or methacholine-induced acid secretion in Heidenhain pouch dogs. [ABSTRACT FROM AUTHOR]

Low-lying excited levels of231Th fed through α-decay of235U were investigated by using α-γ and γ-γ coincidence technique. From the analyses for co-relating energy levels and transition intensities, we found that the most favorable transition from 205.3 keV ([631]7/2) level that is fed by the most dominant α transition from235U is 19.6 keV transition (205.3 keV [631]7/2−→185.7 keV [631]5/2−). We also found that the transition probability of 109.2 keV, 205.3 keV [631]7/2−→96.1 keV [633]9/2+, was corrected to be weak. These findings can explain why the 185.7 keV γ-ray is so strongly observed, 0.57 photons/ga, in the γ-spectrum associated with the α-decay of235U. The decay scheme of231Th levels previously reported has been modified according to the present analysis. [ABSTRACT FROM AUTHOR]