Biomedical subjects

Masaki Hayashi

Publications and source records attributed to Masaki Hayashi.

12 recordsLinked to original sources

PubMed2006

Genetics of symbiosis in Lotus japonicus: recombinant inbred lines, comparative genetic maps, and map position of 35 symbiotic loci.

Development of molecular tools for the analysis of the plant genetic contribution to rhizobial and mycorrhizal symbiosis has provided major advances in our understanding of plant-microbe interactions, and several key symbiotic genes have been identified and characterized. In order to increase the efficiency of genetic analysis in the model legume Lotus japonicus, we present here a selection of improved genetic tools. The two genetic linkage maps previously developed from an interspecific cross between L. japonicus Gifu and L. filicaulis, and an intraspecific cross between the two ecotypes L. japonicus Gifu and L. japonicus MG-20, were aligned through a set of anchor markers. Regions of linkage groups, where genetic resolution is obtained preferentially using one or the other parental combination, are highlighted. Additional genetic resolution and stabilized mapping populations were obtained in recombinant inbred lines derived by a single seed descent from the two populations. For faster mapping of new loci, a selection of reliable markers spread over the chromosome arms provides a common framework for more efficient identification of new alleles and new symbiotic loci among uncharacterized mutant lines. Combining resources from the Lotus community, map positions of a large collection of symbiotic loci are provided together with alleles and closely linked molecular markers. Altogether, this establishes a common genetic resource for Lotus spp. A web-based version will enable this resource to be curated and updated regularly.

Alleles↗

PubMed2006

Cost-effectiveness of tonsillectomy for recurrent acute tonsillitis.

OBJECTIVES: We used a retrospective case series to perform a preliminary study to determine the clinical effectiveness and cost-effectiveness of tonsillectomy for recurrent acute tonsillitis. METHODS: We studied 25 children and 16 adults who had tonsillectomy for recurrent acute tonsillitis. The adult patients and the children's caregivers were asked to respond to a questionnaire regarding the efficacy of their tonsillectomy. The cost of medical care and the work disability cost for tonsillitis and for tonsillectomy were calculated. We then applied the technique of break-even time analysis to assess when the total health care cost savings from surgery overtook the total cost of tonsillectomy. RESULTS: In children, the overall economic costs (medical costs and work-related costs) were recovered at 1.6 years after tonsillectomy (break-even point). In adults, the overall economic costs (medical costs and work-related costs) were recovered at 2.5 years after tonsillectomy (break-even point). CONCLUSIONS: Tonsillectomy for recurrent acute tonsillitis is both clinically effective and cost-effective for children and adults in Japan.

Acute Disease↗

PubMed2005

Phase II study of oral fludarabine phosphate in relapsed indolent B-Cell non-Hodgkin's lymphoma.

PURPOSE: Although intravenous (IV) fludarabine phosphate is effective against indolent B-cell non-Hodgkin's lymphoma (B-NHL), IV administration for 3 to 5 consecutive days is inconvenient in an outpatient setting. To assess the efficacy and toxicity of oral fludarabine phosphate in patients with indolent B-NHL, we conducted a multicenter phase II study. PATIENTS AND METHODS: Patients with relapsed indolent B-NHL received fludarabine phosphate tablets orally once daily on days 1 through 5 every 28 days for three to six cycles. The efficacy was separately analyzed in a mantle-cell lymphoma (MCL) cohort and indolent B-NHL except for MCL (IL) cohort. The primary end point was the overall response rate (ORR). RESULTS: Fifty-two patients, including 46 in the IL cohort (41 with follicular lymphoma) and six in the MCL cohort, were registered, and all patients were eligible. Forty-one patients (79%) had received rituximab as prior therapy. In the IL cohort, the ORR and complete response rate were 65% (30 of 46 patients; 95% CI, 50% to 79%) and 30% (14 of 46 patients; 95% CI, 18% to 46%), respectively. One of six patients with MCL achieved a partial response. The median times to treatment failure for the 46 patients in the IL cohort and for the six patients in the MCL cohort were 8.6 and 6.1 months, respectively. Hematologic toxicities, including grade 4 neutropenia (37%), were the most frequent toxicities, and nonhematologic toxicities were mild. CONCLUSION: Oral fludarabine phosphate is highly effective in patients with relapsed indolent B-NHL who have mostly been pretreated with rituximab and is more convenient than the IV formulation.

Administration, Oral↗

PubMed2005

Tonsillitis index: an objective tool for quantifying the indications for tonsillectomy for recurrent acute tonsillitis.

This report is a preliminary exploration of the concept of a "Tonsillectomy Index" (TI) as an objective tool for quantifying the indications for tonsillectomy for recurrent acute tonsillitis (AT). The TI is derived by multiplying the number of episodes of AT by the number of years during which the episodes of AT occurred. Our objective in this study was to investigate whether there is a relationship between the natural history of AT, the immunological functions of tonsils and our proposed TI. For the natural history of AT, we medically followed 11 children with a history of AT for 5 years. When TI was equal to or greater than 8 (TI> or =8), the children suffered a significantly greater number of episodes of AT. For the immunological portion of our study, we enrolled 36 children and 46 adults undergoing tonsillectomy for either AT (study group) or tonsillar hypertrophy (control group, CG). We analyzed the co-stimulatory signals, CD80 and CD86 on tonsillar B-lymphocytes. The expression rates of CD80 and CD86 in the AT group with TI> or =8 were significantly decreased compared to those with TI was less than 8 (TI<8), as well as with those in control (tonsillar hypertrophy) group. Our preliminary findings suggest that when the TI> or =8, the tonsils have deteriorated immunologically and spontaneous resolution of recurrent AT is less likely to occur, hence tonsillectomy is appropriate. TI may be a useful tool for surgical decision making.

Acute Disease↗

PubMed2005

Lotus burttii takes a position of the third corner in the lotus molecular genetics triangle.

In order to consolidate molecular genetic system in Lotus japonicus and to further access the biological diversity in Lotea, we introduce here Lotus burttii B-303 derived from West Pakistan as the third crossing partner of the Gifu ecotype (B-129-S9) for a genetic analysis. L. burttii is a relatively small and early flowering plant with non-shattering behavior. The general chromosome morphology is very similar to Gifu, and fluorescence in situ hybridization (FISH) analysis revealed that the short arm of chromosome 1 in L. burttii is comparable to that of Gifu, indicating that the translocation event involving chromosomes 1 and 2, which was observed in L. japonicus Miyakojima MG-20, is not present in L. burttii. In addition L. burttii has a higher level of DNA polymorphism compared to Gifu and MG-20 enabling design of codominant markers such as SSR, CAPS and dCAPS. Using an F2 population from a cross between Gifu and L. burttii, codominant makers that co-segregated at the translocation site could be expanded. In order to normalize the genetic background, L. burttii was inbred for nine generations and the germplasm L. burttii B-303-S9 was established.

Base Sequence↗

PubMed2005

Fine mapping of the FT1 locus for soybean flowering time using a residual heterozygous line derived from a recombinant inbred line.

Fine-mapping of loci related to complex quantitative traits is essential for map-based cloning. A residual heterozygous line (RHL) of soybean (Glycine max) derived from a recombinant inbred line (RIL) was used for fine-mapping FT1, which is a major quantitative trait locus (QTL) responsible for soybean flowering time. The residual heterozygous line RHL1-156 was selected from the RILs that were derived from two distantly related varieties, Misuzudaizu and Moshidou Gong 503. The genome of RHL1-156 contains a heterozygous segment (approximately 17 cM) surrounding the FT1 locus but is homozygous in other regions, including three other loci affecting flowering time. A large segregating population of 1,006 individuals derived by selfing of RHL1-156 included two homozygous genotypes for the nearest marker of FT1 whose flowering time differed by 26 days. No continuous range of phenotypes was observed, in contrast to the F2 population, suggesting that a single FT1 locus affected the flowering time in the RHL1-156 line. Linkage analysis revealed that the FT1 locus mapped as a single Mendelian factor between two tightly linked DNA markers, Satt365 and GM169, at distances of approximately 0.1 cM and 0.4 cM, respectively. Our results show that a RHL derived from RILs can be used to fine-map a QTL and that RHLs can be an efficient tool for a systematic fine-mapping of QTLs.

Breeding↗

PubMed2005

Phase I study of radioimmunotherapy with an anti-CD20 murine radioimmunoconjugate ((90)Y-ibritumomab tiuxetan) in relapsed or refractory indolent B-cell lymphoma.

We conducted a phase I study to evaluate the safety and efficacy of radioimmunotherapy with yttrium-90-ibritumomab tiuxetan (Y2B8) in Japanese patients with relapsed or refractory indolent B-cell lymphoma. Indium-111-labeled ibritumomab tiuxetan (In2B8; 3.5 or 5 mCi [129.5 or 185 MBq]) was administered on day 1, followed by serial gamma-camera imaging to investigate the distribution of In2B8 in the whole body of patients and to judge the feasibility of Y2B8 administration. Y2B8 with a dose of 0.3 mCi/kg (11.1 MBq/kg) or 0.4 mCi/kg (14.8 MBq/kg) was administered on day 8. Grade 4 neutropenia and grade 3 thrombocytopenia were observed in three of nine of the patients evaluated for safety. Critical toxicities (prolonged thrombocytopenia or severe non-hematological toxicities) were observed in two of six patients in the 0.4 mCi/kg (14.8 MBq/kg) dose group but were not seen in any of the three patients in the 0.3 mCi/kg (11.1 MBq/kg) dose group. The non-hematological toxicities of the nine patients were of grade 2 or less, except in two patients who had been heavily treated previously. They experienced critical toxicities such as infection, diarrhea, hyponatremia and prolonged thrombocytopenia, as well as other frequent grade 2 non-hematological toxicities. Although the pharmacokinetic profiles were similar to those in the US study, one of the two patients was clarified retrospectively as showing abnormal biodistribution of In2B8 in the bone marrow, as judged by an independent third party panel of radiologists. Five of the 10 participants achieved complete responses or unconfirmed complete responses and two partial responses. In conclusion, the recommended dose of Y2B8 for the subsequent phase II study for Japanese patients is 0.4 mCi/kg (14.8 MBq/kg). This dose of radioimmunotherapy was feasible when patients with altered biodistribution of In2B8 were excluded, and it was highly effective. (Cancer Sci 2005; 96: 903-910).

Adult↗

PubMed2005

klavier (klv), a novel hypernodulation mutant of Lotus japonicus affected in vascular tissue organization and floral induction.

A novel hypernodulation mutant line was isolated from Lotus japonicus Miyakojima MG-20 by irradiation with a helium ion beam. This mutant, named klavier (klv), had roots that were densely covered with small nodules. The nodulation zone of klv was significantly wider than that of the wild type. Grafting experiments showed that klv is impaired in the long-distance shoot-to-root autoregulatory mechanism. Thus the shoot genotype was found to be responsible for the negative regulation of nodule development by KLV. Nodulation of klv showed a higher tolerance to nitrogen (KNO3) than the wild type, which is a common feature of hypernodulating mutants. In addition to an increased number of nodules, the klv mutant showed convex leaf veins on the adaxial leaf surface, markedly delayed flowering and dwarf phenotypes. Microscopic examination of the leaf veins revealed that they were discontinuous. Other phenotypes such as fasciated stems, increased number of flowers and bifurcated pistils were also frequently observed in the klv mutant. Among these phenotypes, hypernodulation, aberrant leaf vein formation and significantly delayed flowering were all linked in a monogenic and recessive manner, indicating that these phenotypes are caused by either a single mutation, or tightly linked mutations. KLV was mapped within 0.29 cM on the long arm of chromosome 1.

Flowers↗

PubMed2004

Immunity of tonsil and IgA nephropathy--relationship between IgA nephropathy and tonsillitis.

Our study hypothesized that cytokines or chemokines induced in tonsils by infectious stimulations play an important role on the exacerbation of the glomerular injuries in patients with IgA nephropathy (IgAN). Tonsils from six patients with IgAN diagnosed by renal biopsy were studied after getting their written informed consents Tonsils from six patients with tonsil disorders with non-renal disorders were examined as controls. Tonsillar mononuclear cells (TMCs) were isolated and resuspended with RPMI 1640 with 10% FCS. These cells were incubated for 48 h with staphlococcus enterotoxin-B (SEB) or lipopolysaccaride (LPS). The levels of IL-6, IL-8, IL-12 and MCP-1 in the supernatants were measured by solid-phase enzyme-linked immunosorbent assay (ELISA) kits. The actual cytokine concentrations were calculated by determining the standard curves. The experiments were performed in duplicate, and the mean value was calculated. We found that tonsillar mononuclear cells of IgA nephropathy produced mesangial proliferative chemokines (MCP-1, IL-8) in higher amounts compared to tonsils from non-IgA nephropathy. This result suggests that upper respiratory tract infections such as tonsillitis may be one of the risk factors of the aggravation in patients with IgA nephropathy.

Cells, Cultured↗

PubMed2002

HAR1 mediates systemic regulation of symbiotic organ development.

Symbiotic root nodules are beneficial to leguminous host plants; however, excessive nodulation damages the host because it interferes with the distribution of nutrients in the plant. To keep a steady balance, the nodulation programme is regulated systemically in leguminous hosts. Leguminous mutants that have lost this ability display a hypernodulating phenotype. Through the use of reciprocal and self-grafting studies using Lotus japonicus hypernodulating mutants, har1 (also known as sym78), we show that the shoot genotype is responsible for the negative regulation of nodule development. A map-based cloning strategy revealed that HAR1 encodes a protein with a relative molecular mass of 108,000, which contains 21 leucine-rich repeats, a single transmembrane domain and serine/threonine kinase domains. The har1 mutant phenotype was rescued by transfection of the HAR1 gene. In a comparison of Arabidopsis receptor-like kinases, HAR1 showed the highest level of similarity with CLAVATA1 (CLV1). CLV1 negatively regulates formation of the shoot and floral meristems through cell-cell communication involving the CLV3 peptide. Identification of hypernodulation genes thus indicates that genes in leguminous plants bearing a close resemblance to CLV1 regulate nodule development systemically, by means of organ-organ communication.

Arabidopsis Proteins↗

PubMedDate not supplied

Temperature-electrical conductivity relation of water for environmental monitoring and geophysical data inversion.

Electrical conductivity (EC) is widely used for monitoring the mixing of fresh water and saline water, separating stream hydrographs, and geophysical mapping of contaminated groundwater. The measured EC values at various temperatures need to be reported as corresponding to a standard temperature because EC is dependent on temperature. An arbitrary constant is commonly used for temperature compensation assuming that EC-temperature relation is linear (for example 2% increase of EC per 1 degrees C). This paper examines the EC-temperature relation of natural waters having vastly different compositions and salinities. EC-temperature relation was slightly nonlinear in a temperature range 0-30 degrees C, but the linear equation approximated the relation reasonably well. The temperature compensation factor corresponding to 25 degrees C ranged between 0.0175 and 0.0198. When the mean value 0.0187 was used, the error of estimating EC at 25 degrees C from EC at 10 degrees C was less than about 2% for all samples tested. Temperature compensation factors vary substantially depending on the choice of standard temperature. Therefore, a care must be taken when standard temperatures different from 25 degrees C are used.

Calibration↗

PubMedDate not supplied

Effects of ground water exchange on the hydrology and ecology of surface water.

Ground water exchange affects the ecology of surface water by sustaining stream base flow and moderating water-level fluctuations of ground water-fed lakes. It also provides stable-temperature habitats and supplies nutrients and inorganic ions. Ground water input of nutrients can even determine the trophic status of lakes and the distribution of macrophytes. In streams the mixing of ground water and surface water in shallow channel and bankside sediments creates a unique environment called the hyporheic zone, an important component of the lotic ecosystem. Localized areas of high ground water discharge in streams provide thermal refugia for fish. Ground water also provides moisture to riparian vegetation, which in turn supplies organic matter to streams and enhances bank resistance to erosion. As hydrologists and ecologists interact to understand the impact of ground water on aquatic ecology, a new research field called "ecohydrology" is emerging.

Animals↗