Biomedical subjects

Takeshi Uno

Publications and source records attributed to Takeshi Uno.

3 recordsLinked to original sources

PubMed2007

Peptide-nucleic acid-modified ion-sensitive field-effect transistor-based biosensor for direct detection of DNA hybridization.

Here, we report the development of a peptide-nucleic acid (PNA)-modified ion-sensitive field-effect transistor (IS-FET)-based biosensor that takes advantage of the change in the surface potential upon hybridization of a negatively charged DNA. PNA was immobilized on a silicon nitride gate insulator by an addition reaction between a maleimide group introduced on the gate surface, the succinimide group of N-(6-maleimidocaproyloxy) succinimide, and the thiol group of the terminal cysteine in PNA. The surface was characterized after each step of the reaction by X-ray photoelectron spectroscopy analysis, and the kinetic analysis of the hybridization events was assessed by surface plasmon resonance. In addition, we measured the -potential before and after PNA-DNA hybridization in the presence of counterions to investigate the change in surface charge density at the surface-solution interface within the order of the Debye length. On the basis of the zeta-potential, the surface charge density, DeltaQ, calculated using the Grahame equation was approximately 4.0 x 10(-3) C/m2 and the estimated number of hybridized molecules was at least 1.7 x 10(11)/cm2. The I-V characteristics revealed that the PNA-DNA duplexes induce a positive shift in the threshold voltage, VT, and a decrease in the saturated drain current, ID. These results demonstrate that direct detection of DNA hybridization should be possible using a PNA-modified IS-FET-based biosensor. PNA is particularly advantageous for this system because it enables highly specific and selective binding at low ionic strength.

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PubMed2006

Alteration of regional cerebral blood flow in patients with chronic pain--evaluation before and after epidural spinal cord stimulation.

BACKGROUND: Chronic pain is defined as intractable pain caused by abnormal pain transmission or impairment of the pain control system per se. Alteration of regional cerebral blood flow (rCBF) is known to occur under the presence of pain stimulation. Epidural spinal cord stimulation (SCS) is occasionally effective in relieving the symptom. OBJECTIVE: The aim of the current study is to investigate the alteration of rCBF in baseline condition and to find the association between the rCBF change and the efficacy of SCS in chronic pain. METHODS: A total of 18 patients underwent Tc-99m-HMPAO SPECT before and after SCS. Analysis with three-dimensional stereo-tactic surface projections (3D-SSP) with stereo-tactic extraction estimation (SEE) software was adopted to evaluate the rCBF. We assessed the extent score of the abnormal region in each segment (rate of the coordinates with a Z-value that exceeds three kinds of threshold value 2.0, 2.5 and 3.0 in all coordinates within a segment). According to the therapeutic response defined by visual analogue scale, we categorized patients into two groups, the good responder (GR) group (n=12) and poor responder (PR) group (n=6). In the analysis, we compared the extent score in the following two conditions. (1) Comparison between the PR group and normal control group under both baseline condition and after SCS. (2) Comparison between the GR group and normal control group under both baseline condition and after SCS. RESULTS: (1) In the PR group, increased rCBF was observed in left thalamus, bilateral precuneus and bilateral cerebellum under the baseline condition. After SCS, the range of these increased rCBF areas localized but remained. Decrease of rCBF was noted in bilateral subcallosal gyrus, superior temporal gyrus (STG) and bilateral anterior cingulate gyrus (ACG). They localized after SCS, but remained. (2) In the GR group, increased rCBF areas were noted in bilateral precuneus and bilateral cerebellum under the baseline condition. After SCS, they localized in bilateral precuneus but those of bilateral cerebellum remained. Decreased rCBF area was noted in bilateral subcallosal gyrus, STG and bilateral ACG under the baseline. After SCS, they localized in bilateral subcallosal gyrus and bilateral STG. In contrast, they enlarged in bilateral ACG. CONCLUSION: Chronic pain patients demonstrated abnormal rCBF distribution on both baseline and post SCS conditions. Increased rCBF of thalamus and precuneus under both conditions in the PR group and decreased rCBF of ACG under post SCS conditions in the GR group were characteristic patterns. Tc-99m-HMPAO SPECT with 3D-SSP and SEE analysis is likely objective and effective in monitoring and evaluating therapeutic outcome by SCS in chronic pain. In addition, it provides information that is useful in the selection of SCS candidates.

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PubMed2002

Ultradian rhythm of trehalose levels coupled to heat resistance in continuous cultures of the yeast Saccharomyces cerevisiae.

Heat resistance appears to cycle in concert with energy metabolism in continuous culture of the yeast Saccharomyces cerevisiae. To study the mechanism of this oscillation, the authors first examined if heat shock proteins (Hsps) are involved. Neither the protein levels of major Hsps nor the expression of the beta-galactosidase gene as a reporter under the control of the promoter carrying heat-shock element oscillated during the metabolic oscillation. The level of trehalose in yeast cycled with the same periodicity, as did energy metabolism. This oscillation was not found in a GTS1-deleted mutant that also did not show cyclic changes in heat resistance. These results suggest that heat resistance oscillation is induced by fluctuations in trehalose level and not by an oscillatory expression of Hsps. The increase in trehalose began at the start of the respiro-fermentative phase and the decrease began after the elevation of the cyclic adenosine monophosphate (cAMP) level. The authors hypothesize that the synthesis of trehalose parallels the activation of the glycolytic pathway and that trehalose is degraded by trehalase activated by cAMP coupled with the metabolic oscillation in the continuous culture of yeast.

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