Publications by authors named "Akira Takatsuki"
Article Synopsis
- Two novel urushiols (1 and 2) and two known urushiols (3 and 4) were extracted from the leaves of Rhus verniciflua and evaluated for their ability to inhibit HIV-1 reverse transcriptase (RT).
- The new compounds were identified through spectroscopic methods, with compound 2 demonstrating the strongest inhibitory activity (IC50: 12.6 µM), making it 2.5 times more effective than the standard drug adriamycin.
- The research highlights the potential of Rhus verniciflua leaves as a source for developing novel bioactive urushiols that may have therapeutic applications.
To evaluate changes in the visual processing of patients with progressive retinitis pigmentosa (RP) who acquired improved reading capability by eye-movement training (EMT), we performed functional magnetic resonance imaging (fMRI) before and after EMT. Six patients with bilateral concentric contraction caused by pigmentary degeneration of the retina and 6 normal volunteers were recruited. Patients were given EMT for 5 min every day for 8-10 months.
View Article and Find Full Text PDFAriakemicins A (1) and B (2), unusual linear hybrid polyketide-nonribosomal peptide antibiotics, were discovered from the fermentation extract of the marine gliding bacterium Rapidithrix sp. These metabolites were positional isomers with regard to a double bond and chromatographically inseparable, rendering the structure study on a mixture basis. The ariakemicins were composed of threonine, two omega-amino-(omega-3)-methyl carboxylic acids with diene or triene units, and delta-isovanilloylbutyric acid.
View Article and Find Full Text PDFArticle Synopsis
- Researchers developed a noncontact backscatter-mode near-infrared time-resolved imaging system (noncontact B-TRIS) to improve spatial resolution and depth information for absorbers buried in scattering materials, aimed at functional brain mapping.
- The system utilizes mode-locked Ti-sapphire lasers for illumination and a specialized camera for detection, successfully imaging a 70 mm area without making contact.
- Testing with a light-scattering phantom showed that the system can accurately identify the position of buried absorbers with a discrepancy of less than 2 mm, demonstrating its potential for imaging cognitive brain functions.
Article Synopsis
- High-pressure carbon dioxide treatment (HPCT) is a non-thermal sterilization method that primarily kills microorganisms by acidifying their cytoplasm.
- A study on Saccharomyces cerevisiae revealed that mutants with impaired vacuole function (slp1) and vacuolar ATPase (vma1) showed increased sensitivity to HPCT, indicating that these cellular components play a crucial role in resistance.
- The results demonstrated that both vacuolar and plasma membrane H(+)-ATPases help S. cerevisiae tolerate HPCT by managing hydrogen ion levels, thus protecting the cells from acidity.
We designed and synthesized hydrogen bond based probes 1-8 with the exception of known glycosidase inhibition mechanisms, and aglycon specificity of 11 different sources of alpha-glucosidases were investigated using their probes. Probe 4 (2,6-anhydro-1-deoxy-1-[(1-oxopentyl-5-hydroxy)amino]-D-glycero-D-ido-heptitol) showed a potent inhibition of S. cerevisiae alpha-glucosidase among all alpha-glucosidases.
View Article and Find Full Text PDFArticle Synopsis
- BOLD-fMRI measures brain activity by detecting changes in blood flow and oxygen levels in response to brain activation, which typically results in increased MR signal intensity.
- Some studies struggle to identify expected brain activation, leading to confusion about fMRI results.
- The authors categorize brain activation into BOLD-positive, BOLD-negative, and BOLD-silent based on blood flow and oxygen concentration, providing a framework to explain inconsistencies observed in sensory motor studies.
Article Synopsis
- Near infrared spectroscopic imaging for brain function mapping needs enhanced spatial resolution, as current systems using optical fibers have limitations due to their arrangement and detector placement.
- The study proposes using multiple detectors for a single light source to better identify local brain activity, modeled as a local absorber in a scattering medium.
- By analyzing the difference in detected light intensities instead of just absorbance, the research demonstrates that a localized absorber affects the measurements directly above it, supporting improved spatial resolution in imaging techniques.
Nordihydroguaiaretic acid (NDGA) protected microtubules in NRK cells from depolymerization caused by structurally and functionally diverse drugs such as nocodazole, colchicine, vinblastine, and ilimaquinone. Hitherto reported drugs, although structurally unrelated to paclitaxel, stabilize microtubules in a way similar to that of paclitaxel and compete for paclitaxel binding to tubulin. However, NDGA had activity toward microtubules different from the effects of paclitaxel.
View Article and Find Full Text PDFMepanipyrim, a novel inhibitor of pharmacologically induced Golgi dispersion.
Biosci Biotechnol Biochem
January 2003
Article Synopsis
- * The drug caused changes in the Golgi structure and prevented damage to the Golgi caused by nocodazole, indicating its role in stabilizing Golgi during cellular stress.
- * Mepanipyrim's unique effects suggest it could be a useful tool for studying how the Golgi functions and its role in membrane transport and dynamics.
Article Synopsis
- The study focuses on developing specific inhibitors for the M phase of mitosis, targeting proteins involved in cell division rather than tubulins.
- Researchers screened microbial products and identified terpendole E (TerE) as a new inhibitor of the Eg5 protein, which is crucial for spindle formation during mitosis.
- TerE was found to disrupt ATPase activities specific to human Eg5 without affecting microtubule structure in interphase, and its inhibitory effect was independent of previously known functions like acyl-CoA:cholesterol O-acyltransferase (ACAT) inhibition.
Hydrolysis of probe substrates, eight possible monodeoxy and mono-O-methyl analogs of p-nitrophenyl alpha-D-glucopyranoside (pNP alpha-D-Glc), modified at the C-2, C-3, C-4, and C-6 positions, was studied as part of investigations into the glycon specificities of seven alpha-glucosidases (EC 3.2.1.
View Article and Find Full Text PDFPossible implication of Golgi-nucleating function for the centrosome.
Biochem Biophys Res Commun
March 2002
Article Synopsis
- The Golgi apparatus disassembles during mitosis, causing Golgi proteins to disperse, but certain proteins like TGN38 and golgin-97 remain linked to the centrosome throughout the cell cycle in NRK cells.
- This association of TGN38 and golgin-97 with the centrosome is unaffected by various treatments that typically disrupt protein positioning, indicating a unique stability.
- Additionally, evidence suggests that the centrosome may play a crucial role in the organization of the Golgi apparatus by interacting with specific Golgi proteins, even while influenced by different microtubule-targeting drugs.