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R Yamashita

Publications and source records attributed to R Yamashita.

At least 19 recordsLinked to original sources
PubMed2004

Time-frequency analysis for pulse driven ultrasonic microscopy for biological tissue characterization.

The authors have proposed a new type of ultrasonic microscopy for biological tissue characterization. The system is driven by a nanosecond pulse voltage, the generated acoustic wave being reflected at the front and rear side of the sliced tissue. In this report, a time-frequency analysis was applied to determine the sound speed thorough the tissue. Frequency dependence of sound speed was obtained with a myocardium of a rat sliced into 10 microm. As the reflected waveform had a significant amount of oscillating component, the waveform was once subjected to the deconvolution process. As the result, two reflections were clearly separated in time domain. Then these two reflections were separately analyzed by time-frequency analysis. Each reflection was extracted by using a proper window function. Phase angles of these reflections at the same frequency were compared. A sound speed micrograph at an arbitrary frequency in between 50 and 150 MHz was successfully obtained. A tendency was found that the sound speed slightly increases with frequency.

Animals↗
PubMed2001

A synchrotron X-ray study of triclinic LiCa2Nb3O10 with perovskite-type slabs.

The triclinic superstructure of a small crystal of LiCa(2)Nb(3)O(10), lithium dicalcium triniobium decaoxide, has been investigated by synchrotron X-ray diffraction. The unit cell is an almost rectangular parallelepiped, although there is a 0.245 degrees offset from orthogonality for beta. The structure essentially belongs to a homologous series of Li[Na(n-3)Ca(2)Nb(n)O(3n+1)] with n = 3, where the moiety in square brackets has a perovskite-type slab structure. The superstructure has a doubled unit-cell volume with respect to the tetragonal aristotype. The NbO(6) octahedra are rotated about axes parallel to [110] by approximately 10 degrees. Adjacent slabs are connected by Li atoms and are geometrically related by 4(2) pseudosymmetry lying parallel to c. There are twice as many sites as Li atoms, providing a variation of population at these Li sites.

Journal Article↗
PubMed2001

A comprehensive collection of mouse zinc finger motifs compiled by molecular indexing.

The C(2)H(2) zinc finger motif found in many transcription factors is thought to be for nucleic acid binding and/or dimerization. Nearly 1% of eukaryote genes are estimated to encode this motif. We investigated the gene family encoding this motif in the Mus musculus mRNA by molecular indexing, a technique used to select a subpopulation of cDNA by ligation of adapters to cDNA fragments digested by a class IIS restriction enzyme(s). In place of oligo-dT primers in the original method, a polymerase chain reaction primer designed based on the conserved sequence of the C(2)H(2) zinc finger protein stranded cDNA was made from various mouse tissue mRNAs, digested with FokI and BsmAI, and joined with adapters. Amplification of the cDNA with an adapter primer and zinc finger-specific primer yielded products enriched in zinc finger protein genes. Fragments were separated by subsequent denaturing polyacrylamide gel electrophoresis, and characterized by DNA sequencing. Consequently, 259 C(2)H(2) zinc finger motif sequences were obtained, among which 166 were novel. Combined with the reported sequences, these mouse motif sequences were compared with those of other species such as Saccharomyces cerevisiae and Caenorhabditis elegans. Some of the amino acids in the motif sequence showed strong bias among species. Most of the novel sequences were supposed to be DNA-binding according to the surface potential of predicted tertiary structures.

Amino Acid Motifs↗
PubMed2001

Myosin I mutants with only 1% of wild-type actin-activated MgATPase activity retain essential in vivo function(s).

The single class I myosin (MYOA) of Aspergillus nidulans is essential for hyphal growth. It is generally assumed that the functions of all myosins depend on their actin-activated MgATPase activity. Here we show that MYOA mutants with no more than 1% of the actin-activated MgATPase activity of wild-type MYOA in vitro and no detectable in vitro motility activity can support fungal cell growth, albeit with a delay in germination time and a reduction in hyphal elongation. From these and other data, we conclude that the essential role(s) of myosin I in A. nidulans is probably structural, requiring little, if any, actin-activated MgATPase or motor activity, which have long been considered the defining characteristics of the myosin family.

Actins↗
PubMed2001

Tissue-engineered product: allogeneic cultured dermal substitute composed of spongy collagen with fibroblasts.

Recently, various types of allogeneic skin substitutes including cultured epidermal substitute (CES), cultured dermal substitute (CDS), and cultured skin substitute (CSS), which are composed of keratinocytes and/or fibroblasts as the cellular component(s), have been used as biological wound dressings. In our study, the allogeneic CDS was prepared by plating fibroblasts on a spongy collagen. The clinical evaluation was conducted using fresh or cryopreserved allogeneic CDS. In 145 of our clinical cases, 95% (138/145) of various wounds were evaluated as achieving good or excellent results, including 96% (22/23) of deep dermal burns (DDB) and dermal burns (DB), 100% (53/53) of partial-thickness donor wounds, 91% (21/23) of traumatic skin defects, 100% (5/5) of pressure ulcers, 82% (9/11) of chronic skin ulcers, 100% (6/6) of coverage for debrided DB, and 92% (22/24) of coverage for autologous meshed graft. The results obtained in our study suggest that the allogeneic CDS is able to provide an effective therapy for patients with partial and/or full-thickness skin defects.

Aged↗
PubMed2001

Characterization of coagulase from Staphylococcus intermedius.

A protein coagulase was isolated from Staphylococcus intermedius 6131 using bovine prothrombin-Sepharose 4B and Bio-gel P-4 column chromatographies. Homogeneity was demonstrated by the formation of a single band in polyacrylamide gel electrophoresis and isoelectric focusing. The purified preparation possesses a molecular weight of 64,500, an isoelectric point of 4.1, consists of 615 total amino acid residues and demonstrates coagulase activity for human and rabbit fibrinogen, but does not show the activity for rat or guinea pig fibrinogens. This purified protein contains galactose and fucose, and the amino-terminal amino acid sequence was determined. The coagulase activity is inhibited by N-bromosuccinimide (NBS), suggesting that tryptophan is involved in this activity. The coagulase was heat stable to 80 degrees C and stable to pH over the range of 7-9. This is the first report of coagulase from Staphylococcus intermedius.

Animals↗
PubMed2000

Frontal sinus adenocarcinoma.

CONTEXT: Paranasal sinus cancer is considered rare, with an incidence of less than 1 per 100,000 per year, with the frontal sinus being the primary site in only 0.3%. We report a case of adenocarcinoma arising in the frontal sinus. DESIGN: Case report. CASE REPORT: A 59-year-old woman, secretary, came in February 1998 with a 4-month history of low intensity frontal headache. She denied contact with wood dust. On examination a non-tender swelling was noted over her right forehead next to the medial aspect of the right orbit. CT scan showed a soft-tissue mass involving frontal sinus with intracranial invasion through the posterior wall. The anterior ethmoid sinus and the medial aspect of the right orbit were also involved. MRI demonstrated dural thickening in communication with the frontal mass. She underwent an en-bloc tumor resection by craniotomy including orbital clearance. Histology revealed an adenocarcinoma. After surgery she had tumor recurrence, and chemotherapy and radiotherapy were started resulting in partial improvement.

Adenocarcinoma↗
PubMed2000

Thyroid function in wholly breast-feeding infants whose mothers take high doses of propylthiouracil.

BACKGROUND: Propylthiouracil (PTU) might theoretically be preferred over methimazole (MMI) during breast-feeding because of its lower milk/serum concentration ratio (0.1 vs. 1.0). The problem is that Graves' disease often relapses during the postpartum period, and high doses of PTU are sometimes needed to control maternal hyperthyroidism) during breast-feeding. However, there are virtually no data on the effects of maternal PTU on thyroid status of infants whose mothers take more than 300 mg PTU daily and who are wholly breast-feeding. OBJECTIVES: To investigate whether mothers can breast-feed without adverse effects on infants' thyroid status while taking 300 mg or more daily of PTU. SUBJECTS AND DESIGN: Eleven infants who were wholly breast-fed while their mothers took PTU 300-750 mg daily for Graves' hyperthyroidism were included in this study. In one of the 11 infants, the mother also took iodine 6 mg daily for a limited period. Thyroid status in these infants was evaluated. MEASUREMENTS: Free T4 (FT4), thyrotrophin (TSH), and TSH binding inhibiting antibody (TBIAb) concentrations were examined at least once in the age range 6 days to 9 months. Maternal blood was also examined for FT4 and TBIAb on the same day, or within a week, of the infants' blood tests. FT4, TSH and TBIAb concentrations at birth were examined, using cord blood, in cases where antithyroid drugs had been continued through delivery. RESULTS: Three of the 11 infants had TSH concentrations higher than the normal range for adults. In one of the three infants, the TSH concentration, which was determined 19 weeks after birth, was just above the normal range. In the remaining two infants whose mothers had taken PTU through delivery, TSH concentrations, determined within 7 days after birth, were distinctly high, but they became normal while maternal PTU doses were the same as or higher than those at the initial examination. Maternal PTU doses or FT4 concentrations were not significantly correlated with infants' TSH concentrations. CONCLUSION: Mothers can breast-feed while taking propylthiouracil at doses as high as 750 mg daily without adverse effects on thyroid status in their infants.

Adult↗
PubMed2000

Regulation of human jaw tapping force with visual biofeedback.

The purpose of this study, which made use of visual biofeedback, was to determine whether jaw tapping force reproduction is related to the strength of tapping and to investigate how jaw tapping force affects the tapping movement curve. Nine healthy examinees were asked to reproduce jaw tapping force. We found that the ease and method of regulating jaw tapping force differed depending on the target force. We also found that jaw tapping force was regulated by alteration of the jaw opening distance, the duration of the tooth contact phase, the duration of the jaw closing phase, the maximum jaw opening velocity, and the maximum jaw closing velocity. However, the duration of the jaw opening phase and cycle time was not affected by force regulation under our experimental conditions.

Adult↗
PubMed1999

Lung carcinoma in patients age younger than 30 years.

BACKGROUND: To the authors' knowledge, no study regarding lung carcinoma patients age <30 years has been published. Therefore, this study was undertaken to define the characteristics of lung carcinoma patients age <30 years. METHODS: Information regarding 26 patients with primary lung carcinoma who were age <30 years was obtained from 10 medical institutions and reviewed retrospectively. For comparison, 304 patients age > or = 30 years who were admitted to the First Department of Internal Medicine at Toyama Medical and Pharmaceutical University between 1980-1996 were studied. RESULTS: Among the characteristics observed in the group of lung carcinoma patients age <30 years was a high incidence of female gender, no history of smoking, so-called "low grade malignancy," American Joint Committee on Cancer Stage I disease, and previous surgical resection. In addition, a low incidence of squamous cell carcinoma was noted, and a more favorable prognosis was observed. CONCLUSIONS: The current study noted clinical features that could be defined clearly in lung carcinoma patients age <30 years.

Adolescent↗
PubMed1999

Head, neck and trunk movements accompanying jaw tapping.

Several studies have examined the functional relationship between mandibular movement and head or body posture, but head and body motion during jaw movement have not been extensively investigated. Ten healthy participants performed repetitive jaw tapping movement. Piezoelectric accelerometers were attached on the surfaces of the participant's forehead, mentum, and over the spinous processes of the sixth cervical, twelfth thoracic and third lumbar vertebrae. The direction in which the antero-posterior acceleration signals appeared around the onsets of jaw opening and closing were observed for the period from the 6th to the 25th strokes of the jaw tapping. Around the onset of jaw opening, the forehead and the lumbar vertebra tended to move posteriorly, but the cervical and thoracic vertebrae moved anteriorly with significant frequencies. The directions of the motions of these locations reversed themselves at the beginning of jaw closing; so the motions of the forehead and the lumbar vertebra were opposed again to the ones of the cervical and thoracic vertebrae. The results suggest that the head extend-flex motion often accompanied the jaw open-close movement, and the motions of the neck and trunk existed, which would serve the purpose of promoting the mandible to move smoothly.

Acceleration↗
PubMed1998

Direct evidence of autosomal recessive inheritance of Arg24 to termination codon in purine nucleoside phosphorylase gene in a family with a severe combined immunodeficiency patient.

Purine nucleoside phosphorylase (PNP) deficiency is a rare immunodeficiency disease involving a T-lymphocyte-dysfunction that is fatal unless bone marrow transplantation is successful. In this study we undertook genetic analysis of a patient with PNP deficiency. Sequencing of the PNP gene, which is located on chromosome 14ql3, of the patient led to the identification of three point mutations in exon 2 at amino acid positions 20 (His, silent mutation), 24 (Arg-->termination codon) and 51 (Ser-->Gly). Intrafamilial sequence analysis of exon 2 revealed that both parents were heterozygous for the Arg24 and termination codon 24 alleles. Two of their three children had inherited different homozygous alleles, termination codon 24 for the patient, and Arg24 for his healthy sibling. Transcriptional termination was suggested as the mechanism giving rise to the disorder in this case. A lack of PNP protein was also confirmed by immunoblot analysis of the patient's hemolysate. This could be the first report providing evidence of autosomal recessive inheritance in PNP deficiency by sequence-based analysis.

Amino Acid Sequence↗
PubMed1998

Chitin-graft-poly(2-methyl-2-oxazoline) enhanced solubility and activity of catalase in organic solvent.

Catalase from bovine liver was lyophilized from an aqueous solution containing chitin-graft-poly(2-methyl-2-oxazoline) (3), which was synthesized by the reaction of 52% deacetylated chitin (1) with living poly(2-methyl-2-oxazoline) (2). The rate of consumption of H2O2 in chloroform catalyzed by the lyophilized catalase with 3 was enhanced more than 10 times that by catalase without 3. The dispersibility and solubility of lyophilized catalase with 3 in chloroform were improved in comparison with catalase itself.

Animals↗
PubMed1998

Propagation of various tooth impacts in the human body.

The purpose of this study was to investigate how far tooth impacts were propagated in the body and whether the propagation would be influenced by posture. The impacts were propagated to all recording sites on the head and neck of the 10 examinees tested. In the recordings on the limbs, even at the most distal site, the number of examinees detecting the vibration was seven out of nine examinees. These results showed that the impacts exerted on the tooth were propagated to distal sites of limbs through the bones and soft tissues and implied that the propagated vibration would influence the whole of the body. On the other hand, as the amplitude of propagated vibration was influenced by posture and recording site, the posture during jaw functioning appears to be important.

Acromion↗
PubMed1998

Transcriptional regulation of fatty acid cyclooxygenases-1 and -2.

Transcriptional regulation of fatty acid cyclooxygenase isozymes (COX-1 and COX-2) were studied using two cell lines. A rapid and transient induction of COX-2 was observed by the addition of tumor necrosis factor alpha (TNF alpha) to murine osteoblastic cells MC3T3-E1. Possible involvement of NF kappa B and NF-IL6 as transcription factors was shown by deletion experiments using a luciferase reporter gene. COX-1 induction by a phorbol ester was demonstrated along with differentiation of human megakaryoblastic cells CMK to megakaryocytes.

Animals↗
PubMed1997

Prostaglandin D synthase in human megakaryoblastic cells.

The cytosol fraction of human platelets did not convert prostaglandin (PG) H2 to PGD2. However, a homogenate of human megakaryoblastic CMK cells (precursor cells of platelets) produced PGD2 from PGH2. The PGD synthase activity was localized in the cytosol of CMK cells, and absolutely required glutathione. The catalytic properties and Western and Northern blottings indicated that the enzyme was PGD synthase of the hematopoietic type rather than the lipocalin type. When CMK cells were differentiated to megakaryocytes with phorbol ester along with induction of cyclooxygenase-1, the PGD synthase activity increased about 2-fold for 2 days and then decreased. In another human megakaryoblastic cell line, Dami, the PGD synthase increased about 10-fold by the addition of phorbol ester. Thus, the PGD synthase, which was undetectable in platelets, appeared during differentiation of megakaryoblasts to megakaryocytes.

Chromatography, Affinity↗