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Articles by K Shimada
Total Records ( 3 ) for K Shimada
  K Shimada , H Isoda , T Okada , T Kamae , S Arizono , Y Hirokawa and K. Togashi
 

OBJECTIVE. For this study, we aimed to selectively visualize the intrahepatic portal veins using 3D half-Fourier fast spin-echo (FSE) MR angiography (MRA) with a time-space labeling inversion pulse (T-SLIP) and to optimize the acquisition protocol.

SUBJECTS AND METHODS. Respiratory-triggered 3D half-Fourier FSE scans were obtained in 25 healthy adult subjects combined with two different T-SLIPs: one placed on the liver and the thorax to suppress signals of the liver parenchyma, hepatic veins, and abdominal arteries and the other on the lower abdomen to suppress the ascending signal of the inferior vena cava. One of the most important factors was the inversion time (TI) of the inversion pulse for the liver and thorax. Image quality was evaluated in terms of signal-to-noise ratio, contrast-to-noise ratio, and mean visualization scores at four different TIs: 800, 1,200, 1,600, and 2,000 milliseconds.

RESULTS. Selective visualization of the portal vein was successfully achieved in all volunteers, and anatomic variations were also seen in three subjects. A TI of 1,200 milliseconds was optimal in our protocol because it was sufficient for peripheral portal vein visualization and was most suitable for signal suppression of the hepatic veins and liver parenchyma.

CONCLUSION. Half-Fourier FSE scanning with T-SLIPs enabled selective visualization of the portal vein without an exogenous contrast agent.

  S Koganemaru , T Mima , M. N Thabit , T Ikkaku , K Shimada , M Kanematsu , K Takahashi , G Fawi , R Takahashi , H Fukuyama and K. Domen
 

Patients with chronic stroke often show increased flexor hypertonia in their affected upper limbs. Although an intervention strategy targeting the extensors of the affected upper limb might thus be expected to have benefits for functional recovery, conventional repetitive motor training has limited clinical utility. Recent studies have shown that repetitive transcranial magnetic stimulation could induce motor recovery. The present study tested whether 5 Hz repetitive transcranial magnetic stimulation of the upper-limb area of the primary motor cortex, combined with extensor motor training, had a greater effect on motor recovery than either intervention alone in stroke hemiparesis. Nine patients with chronic subcortical stroke and nine age-matched healthy subjects completed the crossover study. In separate sessions, we examined the single intervention effect of repetitive wrist and finger extension exercises aided by neuromuscular stimulation, the single intervention effect of 5 Hz repetitive transcranial magnetic stimulation and the combined effect of the two interventions. The motor functions were evaluated behaviourally in patients (Experiment 1) and electrophysiologically in healthy subjects (Experiment 2), both before and after the intervention. In addition, we tested the long-term effect by repeating the combined interventions 12 times in patients (Experiment 3). The motor functions were measured again 2 weeks after the end of the repetitive intervention period. In Experiment 1, the combined intervention, but neither of the single interventions, resulted in an improvement of extensor movement (P < 0.0001) and grip power (P < 0.05), along with a reduction of flexor hypertonia (P < 0.01), in their paretic upper limbs. In Experiment 2, only the combined intervention resulted in selective plastic changes of cortico-spinal excitability (P < 0.01), motor threshold (P < 0.001) and silent period (P < 0.01) for the extensors. In Experiment 3, we also confirmed long-term beneficial effects of the combined intervention in patients. These findings indicate that combining motor training with repetitive transcranial magnetic stimulation can facilitate use-dependent plasticity and achieve functional recovery of motor impairments that cannot be attained by either intervention alone. This method could be a powerful rehabilitative approach for patients with hemiparetic stroke.

  M Shiozuka , A Wagatsuma , T Kawamoto , H Sasaki , K Shimada , Y Takahashi , Y Nonomura and R. Matsuda
 

To induce the readthrough of premature termination codons, aminoglycoside antibiotics such as gentamicin have attracted interest as potential therapeutic agents for diseases caused by nonsense mutations. The transdermal delivery of gentamicin is considered unfeasible because of its low permeability through the dermis. However, if the skin permeability of gentamicin could be improved, it would allow topical application without the need for systemic delivery. In this report, we demonstrated that the skin permeability of gentamicin increased with the use of a thioglycolate-based depilatory agent. After transdermal administration, the readthrough activity in skeletal muscle, as determined using a lacZ/luc reporter system, was found to be equivalent to systemic administration when measured in transgenic mice. Transdermally applied gentamicin was detected by liquid chromatography-tandem mass spectrometry in the muscles and sera of mice only after depilatory agent-treatment. In addition, expansion of the intercellular gaps in the basal and prickle-cell layers was observed by electron microscopy only in the depilatory agent-treated mice. Depilatory agent-treatment may be useful for the topical delivery of readthough-inducing drugs for the rescue of nonsense mutation-mediated genetic disorders. This finding may also be applicable for the transdermal delivery of other pharmacologically active molecules.

 
 
 
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