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Biomedical subjects

Katsuhiro Kobayashi

Publications and source records attributed to Katsuhiro Kobayashi.

25 records · Page 2Linked to original sources
PubMed2002

First total syntheses of the phytotoxins solanapyrones D and E via the domino Michael protocol.

The phytotoxins solanapyrones D (1) and E (2) have been synthesized from the decalone prepared by the domino Michael reaction of the kinetic enolate of optically pure acetylcyclohexene with methyl crotonate. The decalone was transformed into a solanapyrone core by equilibration into thermodynamically stable trans-decalone (11), dehydroxylation, and dehydration. Condensation of a methyl acetoacetate equivalent followed by cyclization installed a pyrone moiety. Introduction of a formyl or hydroxymethyl unit into the pyrone ring via Pummerer related reactions furnished solanapyrones D (1) and E (2).

Alternaria↗
PubMed2002

Childhood-onset epilepsy associated with polymicrogyria.

To study the electroclinical characteristics of patients with childhood-onset epilepsy who showed polymicrogyria (PMG) on MRI, we classified 15 patients according to the location of PMG on MRI. The composition of the subjects was as follows: four patients with PMG in both hemispheres; three with localized PMG in one hemisphere associated with other lesions such as porencephaly; and eight with only localized PMG in one hemisphere. We investigated the electroclinical characteristics of the epileptic syndromes associated with these different types of PMG. Four patients suffered from infantile spasms during their clinical course. Five patients suffered from epilepsy with electrical status epilepticus during slow sleep (ESES) and ESES-related epilepsy. The other six patients had only localization-related epilepsy throughout their clinical course. Patients with PMG in both hemispheres, and localized PMG in one hemisphere associated with other lesions tended to have early-onset intractable seizures, especially infantile spasms. On the other hand, patients with only localized PMG in one hemisphere had ESES and ESES-related epilepsy or localization-related epilepsy, and their seizure prognosis was relatively favorable. These findings are useful in predicting the outcome of patients with PMG.

Adolescent↗
PubMed2002

Systematic source estimation of spikes by a combination of independent component analysis and RAP-MUSIC. I: Principles and simulation study.

OBJECTIVES: We propose a combination of independent component analysis (ICA) and recursively applied and projected multiple signal classification (RAP-MUSIC) as a new approach to dipole source estimation of epileptiform discharges. The method is minimally dependent on subjective decisions. METHODS: Ten electroencephalographic (EEG) data matrices were generated by computer, each matrix including real background activity from a normal subject and an array of added simulated spikes. Each spike was a summation of two transients originating from slightly different 'original dipole sources'. The unaveraged EEG matrices were decomposed by ICA, and source estimation was performed by applying RAP-MUSIC to the spatial information defined by the ICA components showing epileptiform activity in their waveform. For comparison, dipoles were also estimated from the same matrices using two existing methods: RAP-MUSIC based on eigen-decomposition of the covariance matrices of averaged spikes and common spatial pattern decomposition. RESULTS: In every simulated EEG data matrix, two dipoles close to the original sources were estimated by the present method. Their unaveraged activities were also similar to those of the original sources. The two existing methods gave less precise results than the proposed method. CONCLUSIONS: RAP-MUSIC based on ICA thus proved promising for source estimation of unaveraged epileptiform discharges.

Brain↗
PubMed2002

Systematic source estimation of spikes by a combination of independent component analysis and RAP-MUSIC. II: Preliminary clinical application.

OBJECTIVES: We tried to estimate epileptic sources by a combination of independent component analysis (ICA) and recursively applied and projected multiple signal classification (RAP-MUSIC) in real epileptiform EEG discharges. METHODS: EEG data including an array of spikes from 3 patients were decomposed by ICA, and source estimation was performed by applying RAP-MUSIC to the spatial information defined by the set of ICA components that showed epileptiform activity in their waveform. Sources were also estimated from the same data using RAP-MUSIC based on eigen-decomposition of the covariance matrix of averaged spikes, and common spatial pattern decomposition for comparison. RESULTS: RAP-MUSIC based on ICA could estimate generally correct epileptic sources in the 3 patients, and its results were better than those of the other methods, when compared to intracerebral data. The present analysis proceeded without introduction of subjective decision after data selection. The separation of epileptiform discharges from the background is essential for this analysis, and was successfully performed in the real EEG data. CONCLUSIONS: RAP-MUSIC based on ICA appears promising for estimation of epileptic sources with minimal dependence on subjective decisions in the process of analysis. In particular, it was not necessary to select the number of sources.

Brain↗
PubMed2002

Physicochemical analyses of phase transition and dehydration processes of a new oral 1beta-methylcarbapenem antibiotic agent, CS-834.

The characterizations of the anhydrate (A-form), monohydrate (B1-form), and dihydrate (B2-form) of CS-834 were investigated by powder X-ray diffraction, differential scanning calorimetry (DSC), thermogravimetry-differential thermal analysis (TG-DTA), infrared spectroscopy, and Karl Fischer moisture titration. The typical DSC curve of the B2-form showed five endothermic peaks at 35.0, 46.4, 56.2, 99.2, and 190.4 degrees C and an exothermic peak at 123.4 degrees C. In TG-DTA analysis, the three peaks at 35.0, 46.4, and 56.2 degrees C had a total weight loss of 7.3%, corresponding to the release of two water molecules. From morphological observation under thermomicroscopy, the endothermic peak at 99.2 degrees C was attributed to the melting of the dehydrous crystals (B0-form) and the exothermic peak at 123.4 degrees C to the recrystallization to the A-form crystals. The endothermic peak at 190.4 degrees C was due to the melting of the A-form crystals. After incubation for 6.0 h at 35, 50, 60, and 80 degrees C, the powder X-ray diffraction patterns of the B2-form indicated that it was converted into the A-form via the B1-form and B0-form. Thus CS-834 exists in homologous hydrous crystal forms in multiple-phase transformations with the dehydration of two water molecules.

Administration, Oral↗
PubMedDate not supplied

Neoadjuvant intra-arterial chemotherapy for locally advanced uterine cervical cancer: clinical efficacy and factors influencing response.

PURPOSE: To evaluate the effects of neoadjuvant intra-arterial chemotherapy (NAIC) for locally advanced uterine cervical cancer, and to analyze factors influencing the response to the chemotherapy. METHODS: Thirty-four patients with invasive cervical cancer more than 4 cm in diameter were enrolled in this study. NAIC was performed using cisplatin-based regimens. The response was assessed by magnetic resonance imaging (MRI) and examination of surgical specimens. Pretreatment factors involved in the response to NAIC were evaluated and the relationship between the factors and the prognosis was assessed. RESULTS: Clinical response was achieved in 28 (82%) patients. Thirty-one of 49 invasions in the parametrial halves disappeared. Seventeen of 28 lymph node swellings responded to NAIC. Six of the 14 stage III patients became operable. In the 19 surgical cases, pathologically complete responses were found in four. Twenty-eight of the 38 parametrial halves were free from cancer. No lymph node metastases were found in eight patients. Initial tumor volume was found to be an independent, significant determining factor of the response to NAIC. Patients with initial tumor volumes less than 80 cm3 had a significantly better estimated 5-year disease-free survival rate compared with those with larger tumors. CONCLUSION: NAIC for locally advanced cervical cancer is useful for preoperative tumor reduction. Tumor volume is a significant determining factor for the response to NAIC.

Adenocarcinoma↗