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Biomedical subjects

Y Hayashi

Publications and source records attributed to Y Hayashi.

At least 19 recordsLinked to original sources
PubMed2006

Clonic perseveration in the subacute stage of Japanese encephalitis.

We report a very rare case of Japanese encephalitis (JE) presenting with reversible stereotyped movement in the subacute stage. A 58-year-old woman presented with high fever, headache, nausea, vomiting, and consciousness disturbance. Cranial magnetic resonance imaging (MRI) of fluid attenuated inversion recovery (FLAIR) and T2-weighted image (WI) showed high intensity areas in the bilateral thalamus, caudate nucleus and hippocampus. She developed coma, convulsion, and ballism in the acute stage. One month after onset, she showed rhythmic, stereotyped, repetitive movements with hypoperfusion in the thalamus and frontal cortex on single photon emission computed tomography (SPECT). Three months later, her stereotyped movement improved accompanied by recovery of hypoperfusion in the thalamus and frontal cortex on SPECT. We speculated that her stereotyped movement was clonic perseveration due to frontal dysfunction induced by thalamofrontal disconnection.

Brain↗
PubMed2006

The intra-arterial injection of microglia protects hippocampal CA1 neurons against global ischemia-induced functional deficits in rats.

In the present study, we have attempted to elucidate the effects of the intra-arterial injection of microglia on the global ischemia-induced functional and morphological deficits of hippocampal CA1 neurons. When PKH26-labeled immortalized microglial cells, GMIR1, were injected into the subclavian artery, these exogenous microglia were found to accumulate in the hippocampus at 24 h after ischemia. In hippocampal slices prepared from medium-injected rats subjected to ischemia 48 h earlier, synaptic dysfunctions including a significant reduction of synaptic responses and a marked reduction of long-term potentiation (LTP) of the CA3-CA1 Schaffer collateral synapses were observed. At this stage, however, neither significant neuronal degeneration nor gliosis was observed in the hippocampus. At 96 h after ischemia, there was a total loss of the synaptic activity and a marked neuronal death in the CA1 subfield. In contrast, the basal synaptic transmission and LTP of the CA3-CA1 synapses were well preserved after ischemia in the slices prepared from the microglia-injected animals. We also found the microglial-conditioned medium (MCM) to significantly increase the frequency of the spontaneous postsynaptic currents of CA1 neurons without affecting the amplitude, thus indicating that MCM increased the provability of the neurotransmitter release. The protective effect of the intra-arterial injected microglia against the ischemia-induced neuronal degeneration in the hippocampus was substantiated by immunohistochemical and immunoblot analyses. Furthermore, the arterial-injected microglia prevented the ischemia-induced decline of the brain-derived neurotrophic factor (BDNF) levels in CA1 neurons. These observations strongly suggest that the arterial-injection of microglia protected CA1 neurons against the ischemia-induced neuronal degeneration. The restoration of the ischemia-induced synaptic deficits and the resultant reduction of the BDNF levels in CA1 neurons, possibly by the release of diffusible factor(s), might thus contribute to the protective effect of the arterial-injection of microglia against ischemia-induced neuronal degeneration.

Animals↗
PubMed2006

Arabidopsis thaliana fatty acid alpha-dioxygenase-1: evaluation of substrates, inhibitors and amino-terminal function.

Plant alpha dioxygenases (PADOX) convert fatty acids to 2-hydroperoxy products that are important in plant signaling pathways. The PADOX amino-terminal domain is distinct from that in other myeloperoxidase-family hemoproteins, and the positional specificity and prosthetic group of PADOX distinguish them from the non-heme iron plant lipoxygenases. The constraints of the PADOX active site on potential substrates are poorly understood and only limited structure-function and mechanistic information is available for these enzymes. We developed several bacterial and insect cell systems for expression of recombinant Arabidopsis thaliana PADOX1 and evaluated the enzyme's substrate and inhibitor profiles and explored the functional role of the amino-terminal domain. Substrate specificity studies gave the following relative oxygenase activity values: linolenate, 1.00; linoleate, 0.95; oleate, 0.84; palmitoleate, 0.69; myristate, 0.23; palmitate, 0.17; and gamma-linolenate, 0.16. Methyl esters of myristate, linoleate and linolenate were not oxygenated. 3-Thiamyristate was the only oxygenase substrate that produced pronounced enzyme self-inactivation during catalysis. 3,4-Dehydromyristate inactivated the oxygenase without appreciable oxygen consumption. Several compounds inhibited oxygenase activity, including catechol (K(i) approximately 90 microM), divalent zinc ion (K(i) approximately 50 microM), N,N,N',N'-tetramethyl-p-phenylenediamine (K(i) approximately 20 microM) and cyanide ion (K(i) approximately 5 microM). Zinc ion did not change the K(m) values for linoleate or oxygen, or the K(i) value for cyanide, indicating that zinc acts at a distinct site from the other compounds. Gel-filtration chromatography revealed considerable variation in oligomeric state of recombinant PADOX1 produced in the various expression systems, but oligomeric state was not correlated with activity. Deletion of the first eight or fourteen PADOX1 residues in a NuSA-PADOX1 fusion protein led to 13 and 83% decreases in activity, respectively, indicating the N-terminal region is important for normal catalytic activity.

Arabidopsis↗
PubMed2006

Dielectric properties of glycerol/water mixtures at temperatures between 10 and 50 degrees C.

At six temperatures T between 10 and 50 degrees C and at mole fractions x(g) of glycerol (0<x(g)<or=0.9) the complex (electric) permittivity epsilon(nu) of glycerol/water mixtures has been measured as a function of frequency nu between 1 MHz and 40 GHz. The spectra of the glycerol/water mixtures can be well represented by a Davidson-Cole [J. Chem. Phys. 18, 1417 (1950)] relaxation function that reveals an unsymmetric relaxation time distribution. The effective dipole orientation correlation factor derived from the static permittivity displays an unspectacular behavior upon mixture composition. The dielectric relaxation time reveals a simple relation to the shear viscosity of the mixtures, but both quantities are not proportional to one another. The relaxation times at high temperatures nicely complement previously determined low temperature data, following a Vogel-Fulcher-Tammann-Hesse [Z. Phys. 22, 645 (1925); J. Am. Chem. Ceram. Soc. 8, 339 (1923); Z. Anorg. Allg. Chem. 156, 245 (1926)] (VFTH) temperature dependence. When the Eyring behavior is assumed a limiting high temperature form of the VFTH relation, enthalpy, and entropy of activation values are found which adopt significantly higher values in the glycerol rich mixtures than in the water rich liquids. The relaxation time distribution parameter at high water content indicates a dynamically heterogeneous structure of the liquids. Likely there exist glycerol rich and water rich microphases.

Journal Article↗
PubMed2006

Effects of obesity phenotype on fat metabolism in obese men during endurance exercise.

OBJECTIVE: The effects of obesity phenotype on fat metabolism during endurance exercise are unclear. This study aimed to investigate in obese men whether body fat distribution would influence plasma fat availability and oxidation during endurance exercise. DESIGN: Fourteen sedentary men (body mass index (BMI) > 25 kg/m2) were divided into two groups by visceral fat (VF) area: VF obese (VF-Ob) (n = 7, age; 52.0 +/- 2.5 (s.e.) years) and abdominal subcutaneous fat obese (SF-Ob) (n = 7, age; 57.3 +/- 2.8 (s.e.) years). All participants performed stationary cycling exercise for 60 min at 50% of peak oxygen uptake. MEASUREMENTS: Blood and respiratory gas samples were taken for analysis of hormone, metabolite and substrate oxidation in each participant at rest and during exercise. RESULTS: There is a significant group x time interaction in the plasma concentration of free fatty acid (FFA) (P < 0.05) and glycerol (P < 0.05) during the exercise bout. In addition, total plasma concentration of FFA (area under the curve) was 59.2% higher in VF-Ob compared with SF-Ob men during endurance exercise (1.99 +/- 0.24 and 1.25 +/- 0.13 mEq/l/min, respectively; P < 0.05). Total plasma concentration of glycerol (area under the curve) was 102.3% higher in VF-Ob than SF-Ob men during the exercise (69.6 +/- 12.5 and 34.4 +/- 5.1 mg/dl/min, respectively; P < 0.05). However, fat oxidation was not different throughout the exercise between VF-Ob and SF-Ob men (176.5 +/- 25.7 and 183.0 +/- 12.8 kcal/60 min, respectively). CONCLUSION: During moderate endurance exercise, plasma fat availability may be higher in men with VF obesity compared to men with SF obesity. However, total fat oxidation is similar between obesity phenotype.

Analysis of Variance↗
PubMed2006

Estimation of photon dose generated by a short pulse high power laser.

The authors obtain a new equation to estimate the forward component of a photon dose generated through the interaction between a target and a short pulse high power laser. As the equation is quite simple, it is useful for calculating the photon dose. The equation shows that the photon dose is proportional to the electron temperature in the range>3 MeV and proportional to the square of the electron temperature in the range<3 MeV. The dose estimated with this method is roughly consistent with the result of Monte Carlo simulation. With some assumptions and corrections, it can reproduce experimental results obtained and the dose result calculated at other laboratories.

Electrons↗
PubMed2006

Influence of phase transformation on the torsional and bending properties of nickel-titanium rotary endodontic instruments.

AIM: To investigate the relationship between the functional properties and the phase transformation of nickel-titanium endodontic instruments. METHODOLOGY: Five types of rotary nickel-titanium endodontic instruments with a 0.30 mm diameter tip (EndoWave, HERO 642, K3, ProFile.06, and ProTaper) were selected to investigate torsional and bending properties, and phase transformation behaviour. A torsional test was performed according to ISO publication 3630-1, and maximum torque and angular deflection at fracture were measured. Bending load of the instruments was measured in a cantilever-bending test at 37 degrees C with the maximum deflection of 4.0 mm. A stainless steel K-file was used for reference. Phase transformation behaviour was measured by differential scanning calorimetry (DSC). From the DSC curve, transformation temperatures were calculated. Data were analysed by anova and the Tukey-Kramer's test. RESULTS: The maximum torsional torque values of HERO, K3 and ProTaper were significantly higher (P < 0.05) than those of EndoWave, ProFile and K-file. The K-files had the lowest torque value. Angular deflection at fracture was significantly higher (P < 0.05) for K-files than that for any nickel-titanium instrument. The bending load values of HERO and K3 were significantly higher (P < 0.05) than those of EndoWave, ProFile, ProTaper and K-file. The K-files had the lowest load value, although residual deflection remained. The transformation temperatures of HERO and K3 were significantly lower (P < 0.05) than those of EndoWave, ProFile and ProTaper. CONCLUSIONS: The functional properties of nickel-titanium endodontic instruments, especially their flexible bending load level, were closely related to the transformation behaviour of the alloys.

Calorimetry, Differential Scanning↗
PubMed2006

Development of a rapid strain differentiation method for methicillin-resistant Staphylococcus aureus isolated in Japan by detecting phage-derived open-reading frames.

AIMS: To develop a rapid genotyping method for investigating outbreaks of methicillin-resistant strains of Staphylococcus aureus (MRSA) isolated in Japan. METHODS AND RESULTS: Isolates were genotyped by detecting the keeping pattern of 16 open-reading frames (ORFs), a process we call phage ORF typing (POT). Thirteen of the ORFs were selected from phage genomes and one from a genomic island SaGIm in the genome of strain Mu50. The other two ORFs, one from Tn554 and one from staphylococcal cassette chromosome mec (SCCmec) type II, were used as strain markers. Three hundred and sixty-eight isolates from five hospitals were classified into 133 types by POT, whereas they were classified into 139 types by pulsed-field gel electrophoresis (PFGE) subtyping. The discriminatory power of POT (D=0.989) was equal to that of PFGE subtyping (D=0.986). CONCLUSIONS: MRSA isolates collected in Japan can be genotyped by detecting the keeping pattern of phage-derived ORFs with a discriminatory power equal to that of PFGE subtyping. SIGNIFICANCE AND IMPACT OF THE STUDY: MRSA isolates can be genotyped rapidly by detecting phage-derived ORFs. As particular pandemic clones can be found in a specific region, a typing method localized to a pandemic clone may be effective for the rapid genotyping of MRSA during outbreaks.

Bacterial Typing Techniques↗
PubMed2006

The distribution pattern of myofibroblasts in the stroma of human bladder carcinoma depends on their invasiveness.

The presence of myofibroblasts has been elucidated in the stroma of neoplasm of various organs. In the present article, we studied the distribution of myofibroblasts in the stroma of bladder carcinoma. Twenty-five surgical resected bladder tumors (urothelial carcinoma, n = 21; combined urothelial carcinoma and adenocarcinoma, n = 2; sarcomatoid squamous cell carcinoma, n = 1; combined urothelial carcinoma and squamous cell carcinoma, n = 1) were selected and we evaluated the distribution of myofibroblasts using immunohistochemical, electron and immunoelectron microscopic techniques. Immunohistochemically, the distribution pattern of myofibroblasts in invasive and non-invasive carcinomas were predominantly fascicular and reticular forms, respectively. Moreover, myofibroblasts around bladder carcinoma cells were confirmed by electron microscope. Understanding the distribution pattern of myofibroblasts in the stroma of bladder carcinoma may provide available information about the presence of carcinoma invasion.

Actins↗
PubMed2006

Cytokeratin-positive subserosal myofibroblasts in gastroduodenal ulcer; another type of myofibroblasts.

To investigate the distribution and origin of alpha-smooth muscle actin (ASMA)-positive stromal cells in the perforation of human gastroduodenal ulcers. Perforative lesions of 24 surgically resected gastroduodenal ulcers were examined immunohistochemically for ASMA, HCD, CD34, CD31, CAM5.2 and HMW-CK, and double staining of ASMA and CAM5.2 was also performed. In addition, to determine the cell source of collagen, in situ hybridization of collagen I mRNA was performed. In the normal gastroduodenal wall, the reticular network of CD34-positive stromal cells was identified in the muscularis mucosa, submucosa, muscular propria, and subserosa. In the subepithelial area, many myofibroblasts were observed, whereas no CD34-positive stromal cells were seen. In areas neighboring ulcerative lesions, no CD34-positive stromal cells were observed, but a significant number of myofibroblasts were present there. In the deep layer of ulceration, numerous fusiform or stellate stromal cells strongly positive for ASMA and CAM5.2 were observed in the subserosal area around the perforation. In the same site, many cells co-expressing ASMA and CAM5.2 were identified by double staining. In contrast, in the surface layer of ulceration, stromal cells expressing only ASMA were observed. The cytokeratin-positive subserosal myofibroblastic cell in human gastroduodenal ulcer is a novel type of myofibroblast.

Actins↗
PubMed2005

The transcriptional landscape of the mammalian genome.

This study describes comprehensive polling of transcription start and termination sites and analysis of previously unidentified full-length complementary DNAs derived from the mouse genome. We identify the 5' and 3' boundaries of 181,047 transcripts with extensive variation in transcripts arising from alternative promoter usage, splicing, and polyadenylation. There are 16,247 new mouse protein-coding transcripts, including 5154 encoding previously unidentified proteins. Genomic mapping of the transcriptome reveals transcriptional forests, with overlapping transcription on both strands, separated by deserts in which few transcripts are observed. The data provide a comprehensive platform for the comparative analysis of mammalian transcriptional regulation in differentiation and development.

3' Untranslated Regions↗
PubMed2005

Therapy-related myelodysplastic syndrome in childhood: a retrospective study of 36 patients in Japan.

We report here a retrospective analysis of 36 children with therapy-related myelodysplastic syndrome (t-MDS) diagnosed between 1990 and 1999 in Japan. Their median age was 7.7 years and the median latency period for the development of t-MDS was 38.5 months. The primary tumors were hematologic in 15 of the cases and nonhematologic in 21. Chromosomal abnormalities were detected in 32/34(94%) patients: abnormalities of chromosomes 5and/or 7 in 41% and notably, 11q23 abnormalities in 31%. The prognosis of children with t-MDS was very poor as compared to children with primary MDS (5 year survival: 16% versus 54%, p<0.0001).

Adolescent↗
PubMed2005

Dialysis-related amyloidosis of the temporomandibular joint.

Dialysis-related amyloidosis (DRA) is a serious complication occurring most commonly in patients undergoing long-term hemodialysis. We describe a case of amyloidosis of the bilateral temporomandibular joint (TMJ) that developed after long-term hemodialysis therapy.

Aged↗
PubMed2005

Electron acceleration by a nonlinear wakefield generated by ultrashort (23-fs) high-peak-power laser pulses in plasma.

We study experimentally the interaction of the shortest at present (23-fs) , relativistically intense (20-TW), tightly focused laser pulses with underdense plasma. MeV electrons constitute a two-temperature distribution due to different plasma wave-breaking processes at a plasma density of 10(20) cm(-3). These two groups of electrons are shown numerically to constitute bunches with very distinctive time durations.

Journal Article↗
PubMed2005

Mono-(2-ethylhexyl) phthalate (MEHP) induces testicular alterations in male guinea pigs at prepubertal stage.

We have recently shown that MEHP induces spermatogenic cell apoptosis in guinea pigs at prepubertal stage in vitro. To evaluate the effects of MEHP on the testicular tissues of guinea pigs in vivo, we conducted this research work. Five weeks old male guinea pigs were used in this experiment. They received a single oral dose of 2000 mg/ml of MEHP in corn oil by gavage at a volume equal to 4 ml/kg. Control group received a similar volume of corn oil vehicle. Vehicle- and MEHP-treated guinea pigs were sacrificed at the interval of 3, 6, and 9 h, and the testicular tissues were processed for histopathological studies. Distinct histopathological changes were recognized in testes. Detachment and displacement of spermatogenic cells, thin seminiferous epithelia, vacuolization of Sertoli cells were prominent at 6 h after MEHP treatment. The lumina of the efferent ductules were frequently occupied with sloughed seminiferous epithelia from 6 to 9 h after MEHP treatment. Apoptotic spermatogenic cells appeared at 3 h in the control group. The incidence of apoptotic spermatogenic cells significantly increased (*p<0.05) from 3 to 9 h, and the maximal increase of apoptotic spermatogenic cells were observed at 9 h after MEHP treatment. Time-dependent increases of apoptotic spermatogenic cells was recognized throughout the experimental period. It may be suggested here that MEHP also induces spermatogenic cell apoptosis in guinea pigs in vivo and guinea pigs may be considered as a useful animal model for sensitivity test of the reproductive toxicity to some phthalate esters at their earlier stage in vivo.

Animals↗
PubMed2005

Living-related small bowel transplantation: two cases experiences.

We have recently performed living-related small bowel transplantation for 2 patients. The first patient was a 14-year-old boy with total parenteral nutrition (TPN)-dependent short-bowel syndrome associated with hypoganglionosis of the entire intestine. He received a bowel graft from his 43-year-old mother. The second patient was a 27-year-old woman, who had massive enterectomy due to volvulus and developed vitamin deficiencies and severe metabolic disorders as a result of long-term TPN. She underwent living-related bowel transplantation from her 57-year-old mother. Blood types were ABO identical, cytotoxic cross matches were negative, and cytomegalovirus statuses were positive-to-positive in both cases. Up to one third of the donor bowel was harvested from the donor distal ileum more than 30 cm away from the ileocecal valve. The graft vessels were connected to infrarenal aorta, and inferior vena cava. The immunosuppressive regimen consisted of daclizumab, tacrolimus, and steroid. The graft surveillance was accomplished using zoom endoscopy and mucosal biopsy. The first patient developed progressive acute cellular rejection (ACR) on the 9th postoperative day (POD)-9 requiring OKT-3 therapy, which was effective. Two months after transplantation, he was weaned from TPN, tolerating oral intake with a fully functioning graft. The second patient experienced no episode of ACR and was weaned off TPN on POD-29 with a functioning graft. Her metabolic disorder dramatically improved after bowel transplantation. Both donors had no complication and were discharged from the hospital on POD-10. Living-related bowel transplantation is an extreme option of treatment for patients with short-bowel syndrome.

Adolescent↗