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Biomedical subjects

Noriaki Kikuchi

Publications and source records attributed to Noriaki Kikuchi.

5 recordsLinked to original sources
PubMed2006

Circular dichroism of optically active poly(dialkylsilane) aggregates in microcapsules.

Poly[n-hexyl-(S)-3-methylpentylsilane] aggregates confined in microcapsules to keep the aggregation number and ranging in average polymer mass m(p) in a microcapsule from 2 x 10(-)(16) to 2 x 10(-)(14) g were studied by circular dichroism measurements in ethanol (a nonsolvent) and tetrahydrofuran (an associative solvent at low temperature) at various temperatures. The weight-average molecular weight M(w) and the polydispersity index (the ratio of M(w) to the number-average molecular weight) of the polysilane sample were 6.6 x 10(4) and 1.07, respectively, and the average number of polymer molecules in each capsule was estimated to be 1.9 x 10(3) for m(p) = 2 x 10(-)(16) g and 1.7 x 10(5) for m(p) = 2 x 10(-)(14) g. The size of each aggregate did not affect the optical activity because the circular dichroism thus obtained was proportional to m(p) under the same conditions in the investigated m(p) range; on the other hand, the peak height of the circular dichroism in tetrahydrofuran had a significant hysteresis between 0 and 25 degrees C. Moreover, the circular dichroism appreciably reflected the prepared method, that is, the temperature and solvent; in other words, the aggregates memorized the initial conditions in their stacking structures.

Alkylation↗
PubMed2006

Incidence and development of trigger thumb in children.

PURPOSE: Whether trigger thumb is congenital or acquired remains controversial. The purpose of this study was to identify whether trigger thumb is present at birth and to clarify whether trigger thumb represents a developmental condition. METHODS: We examined 1,116 babies born at Yamagata Prefectural Nihonkai Hospital within 14 days after birth. All patients were examined by the author (N.K.), a hand surgeon. Patients were followed up to determine whether trigger thumb would present later even though it was not present at birth. We informed parents about the development of trigger thumb by providing informational sheets for neonatal screenings after hospital discharge. They were asked to check their child for a year or more to see if any flexion deformity of the interphalangeal joint of the thumb occurred. After discharge from the hospital, the family was responsible for noticing trigger thumb in their infant and seeking medical treatment. RESULTS: Trigger thumb was not identified in any patient at birth. Responses were obtained from 601 families. Trigger thumb manifested in 2 thumbs of 2 children in the screening group at 8 and 11 months after birth; however, 3 additional children developed trigger thumb at 15, 21, and 30 months of age. CONCLUSIONS: The incidence of acquired trigger thumb in children 1 year of age was 3.3 per 1,000 live births. It is unlikely that this study identified all cases of trigger thumb in patients older than 1 year in the primary screening group. The results of this follow-up study, however, suggest that trigger thumb is not present at birth but develops with postnatal growth.

Child, Preschool↗
PubMed2004

Oculocutaneous albinism type 4 is one of the most common types of albinism in Japan.

Oculocutaneous albinism (OCA) is a complex genetic disease with great clinical heterogeneity. Four different types of OCA have been reported to date (OCA1, OCA2, OCA3, and OCA4). MATP was recently reported in a single Turkish OCA patient as the fourth pathological gene, but no other patients with OCA4 have been reported. Here, we report the mutational profile of OCA4, determined by genetic analysis of the MATP gene in a large Japanese population with OCA. Of 75 unrelated patients that were screened, 18 individuals (24%) were identified as having OCA4; they harbored seven novel mutations, including four missense mutations (P58S, D157N, G188V, and V507L) and three frameshift mutations (S90CGGCCA-->GC, V144insAAGT, and V469delG), showing that MATP is the most frequent locus for tyrosinase-positive OCA in Japanese patients. We discuss the functional melanogenic activity of each mutant allele, judging from the relationship between the phenotypes and genotypes of the patients. This is the first report on a large group of patients with OCA4.

Adolescent↗
PubMed2004

Plasma volume and blood viscosity during 4 h sitting in a dry environment: effect of prehydration.

BACKGROUND: Deep vein thrombosis and pulmonary thromboembolism are potential problems for travelers, including those who fly. We hypothesized that prehydration with an electrolyte-glucose beverage (EGB) would be better than water for maintaining body fluid balance and preventing increased blood viscosity in immobilized men. METHODS: There were 12 healthy men (24-38 yr) who participated in crossover trials of prehydration using EGB and H2O as well as a control condition (Con) with no prehydration. Fluid intake was set at 6 ml x kg(-1) body weight (mean 418 ml). For each trial, subjects sat for 4 h at a dry-bulb temperature of 23.0-23.5 degrees C and a relative humidity of 18-36%. Plasma volume (PV) and whole blood viscosity (Bvis) were determined every hour; routine laboratory hematological tests, urine volume, and body weight were recorded at 2 h and 4 h. RESULTS: For Con, subjects lost approximately 110 ml h(-1); at 2 h, PV had decreased significantly by 3.4%, and Bvis had increased significantly by 9.3%, with no further change at 4 h. For prehydration, retention of the consumed fluid at 2 h was significantly higher for EGB (57%) than for H2O (38%), while both drinks prevented significant change in PV and Bvis. There were no significant differences between trials in coagulation variables, but Bvis measured at higher shear rates for EGB were significantly attenuated compared with Con. CONCLUSION: EGB and water prevented the increase of blood viscosity that occurred without prehydration. EGB was better than water for maintaining body fluid balance and preventing hypovolemia.

Adult↗