Biomedical subjects

T Miyazaki

Publications and source records attributed to T Miyazaki.

At least 109 records · Page 6Linked to original sources

PubMed2000

Electron spin echo study of long-lived radicals which cause mutation in gamma-ray irradiated mammalian cells.

Long-lived radicals, produced by gamma-ray irradiation of mammalian cells at room temperature, cause mutation and morphological transformation in the cells. The local environment near the long-lived radicals in irradiated cells was investigated here by the analysis of electron spin echo envelope modulation (ESEEM) spectra. The number of hydrogen (deuterium) atoms surrounding the long-lived radical, which may correspond to the number of water molecules, was estimated roughly as one or two. It is postulated that the long-lived radicals are generated in the interior of biopolymers. The radicals are not produced by the reaction of OH radicals, but mainly by the decomposition of biopolymer which absorbed directly the energy of the ionizing radiation.

Albumins↗

PubMed2000

Overexpression of the csk gene suppresses tumor metastasis in vivo.

The non-receptor tyrosine kinase c-Src has been implicated in the development of numerous human cancers. c-Src is activated in colon cancers, particularly in highly metastatic cells, and its overexpression strongly correlates with tumor progression. C-terminal Src kinase (Csk) has been demonstrated to negatively regulate Src family tyrosine kinases through tyrosine phosphorylation at the C-terminal regulatory site (Tyr-527). We report herein that down-regulation of Src kinase activity by adenovirus-mediated csk gene transfer abrogated the highly metastatic phenotype of colon cancer cells. Overexpression of Csk decreased Src tyrosine kinase activity in NL-17 cells, the highly metastatic clone of mouse colon adenocarcinoma 26. Importantly, Csk overexpression in NL-17 cells resulted in significant suppression of in vivo metastasis, without affecting its tumorgenicity. Csk overexpression decreased the invasiveness of NL-17 cells through Matrigel, in vitro reconstituted basement membrane. Gelatin zymography confirmed the decreased protein levels of MMP-2 (gelatinase A) in the supernatants of Csk-overexpressed NL- 17 cells. These results provide a therapeutic basis for interfering with metastasis of colon cancer by csk gene-mediated down-regulation of Src kinase activity.

Adenoviridae↗

PubMed2000

Clinical trial results on the use of a recombinant feline interferon-omega to protect Japanese pearl oysters Pinctada fucata martensii from akoya-virus infection.

Japanese pearl oysters (akoya oyster: Pinctada fucata martensii) are currently suffering mass mortalities from akoya-virus infection. In the present study, akoya oysters were injected with an anti-viral, recombinant feline interferon-omega) (rFeIFN-omega) in an attempt to confer resistance to this virus. In infectivity experiments, oysters were twice injected with rFeIFN-omega at 1 mega unit kg(-1) of the meat weight. They were challenged with a single inoculation of cultured akoya-virus and held for 20 to 30 d at 25 degrees C. Control oysters received only the viral challenge without rFeIFN-omega administration. In prophylactic experiments, oysters that were given the akoya-virus on Days 1 to 5 after rFeIFN-omega administration showed lower mortalities. Furthermore, the survivors had fewer muscular lesions resulting from the virus infection than the controls. In treatment experiments, the virus was inoculated on Days 1 to 3 before rFeIFN-omega administration. None of the treated oysters died within a 30 d experimental period. Survivors displayed repaired lesions with fibrous tissues that were produced by enhanced agranulocytes in the body musculature. Moreover, rFeIFN-omega) was not toxic to akoya oysters. Thus, rFeIFN-omega administration is efficacious in preventing mortality of akoya oysters with akoya-virus infection.

Animals↗

PubMed2000

Spatiotemporal expression of BDNF in the hippocampus induced by the continuous intracerebroventricular infusion of beta-amyloid in rats.

The beta-amyloid protein (Abeta) is the major component of senile plaques found in the brain in Alzheimer's disease (AD). Its neurotoxic properties in vivo, however, are not well defined. Since the expression of neurotrophin genes is considered an important component of the intrinsic neuroprotective response to insults, we analyzed the gene expression of neurotrophins in the brains of rats which received a continuous infusion of Abeta-(1-42) into the cerebroventricle. Northern blot analysis revealed a significant increase in brain-derived neurotrophic factor (BDNF) expression in the hippocampus but no change in the cerebral cortices. The alteration peaked on days 3-7 and returned to the basal level on day 14 after the start of Abeta-(1-42) infusion. No significant changes in nerve growth factor or neurotrophin-3 mRNA expression were observed. The infusion of Abeta-(1-40) and (25-35) also triggered the expression of BDNF mRNA, whereas neither Abeta-(40-1) nor (1-16) had any effect. In situ hybridization histochemistry revealed that the expression mainly occurred in the hilus and granular layer of the dentate gyrus and to a lesser extent in the pyramidal neurons of the CA1 region. These results demonstrate that the continuous intracerebroventricular infusion of Abeta induces selective and spatiotemporal expression of BDNF mRNA in the hippocampus.

Alzheimer Disease↗

PubMed2000

Mutation and expression of the metastasis suppressor gene KAI1 in esophageal squamous cell carcinoma.

BACKGROUND: KAI1/CD82, a tumor metastasis suppressor gene, is correlated inversely with the progression and invasion of several tumors. It also has been reported that the KAI1 gene is related to the tumor suppressor gene p53. This study was performed to clarify the correlation between KAI1/CD82 expression and clinicopathologic characteristics and p53 expression in patients with esophageal squamous cell carcinoma (ESCC). The authors also investigated mutation of the KAI1 gene coding region to determine whether this may reduce KAI1 expression in ESCC. METHODS: Using immunohistochemistry with anti-KAI1 polyclonal antibody and monoclonal antibody against p53, KAI1/CD82 and p53 expression were detected in 55 patients with ESCC who had undergone surgery. The authors examined the KAI1 gene mutation in 22 patients with ESCC by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis and DNA sequencing. RESULTS: KAI1/CD82 expression was positive in 36 of 55 patients (65.5%). There was a significant inverse correlation between KAI1/CD82 expression and regional lymph node metastasis (P = 0.0045), distant metastasis (P = 0.0092), the number of lymph node metastases (P = 0.0019), and pathologic stage (P = 0.0046). The survival rates of KAI1/CD82 negative patients were poorer than those of positive patients (P = 0. 024). The correlation between KAI1 positive and p53 positive tumors was not statistically significant. None of the 22 patients with ESCC showed mutation of the KAI1 gene by PCR-SSCP. In one patient, there was polymorphism in the SSCP assay and DNA sequencing. CONCLUSIONS: The authors demonstrated immunohistochemically that the expression of KAI1 protein appeared to be correlated with lymph node metastasis. Mutation does not seem to be a mechanism for dysregulation of the KAI1 protein in ESCC.

Adult↗

PubMed2000

Genome analysis of collagen disease in MRL/lpr mice: polygenic inheritance resulting in the complex pathological manifestations.

MRL/MpJ-lpr/lpr (MRL/lpr) mice develop collagen disease involving vasculitis, glomerulonephritis, arthritis and sialoadenitis, each of which has been studied as a model for polyarteritis, lupus nephritis, rheumatoid arthritis and Sjögren's syndrome, respectively. In the previous studies, we observed genetic segregation of these complex pathological manifestations throughout the genome recombination with a C57Bl/6-lpr/lpr or a C3H/HeJ-lpr/lpr (C3H/lpr) strain of mice which rarely develops such lesions, indicating that development of collagen disease is dependent on an MRL host genetic background. To clarify the mode of inheritance and the gene loci affecting four types of the lesions in MRL/lpr mice; vasculitis, glomerulonephritis, arthritis and sialoadenitis, a genetic dissection of the lesions was carried out by using MRL/lpr, C3H/lpr, (MRL/lprxC3H/lpr) F1 intercross, and MRL/lprx(MRL/lprxC3H/lpr) F1 backcross mice. Definition of each lesion was performed by histopathology under light microscopy, and genomic DNA of the backcross mice were subjected to association studies by chi-square analysis for determining which polymorphic microsatellite locus occurs at higher frequency among affected compared to unaffected individuals for each lesion. We observed that gene loci recessively associated with each lesion were mapped on different chromosomal positions. We conclude that each of four types of the lesions in MRL/lpr mice is under the control of different set of genes, suggesting the complex pathological manifestations of collagen disease result from polygenic inheritance.

Animals↗

PubMed2000

Simultaneous determination of triclabendazole and its sulphoxide and sulphone metabolites in bovine milk by high-performance liquid chromatography.

A simple method has been developed for the simultaneous determination of triclabendazole and its metabolites (sulphoxide and sulphone) in bovine milk by reversed-phase high-performance liquid chromatography (HPLC). A milk sample was homogenized with sodium sulfate anhydrous and acetonitrile, and centrifuged. The supernatant was isolated, rinsed with n-hexane saturated with acetonitrile, and evaporated. The residue was dissolved with 0.1 M potassium dihydrogenphosphate, and 0.1 M sodium hydrogencarbonate, and then cleaned up on a Bond Elut C18 cartridge. The three compounds were separated on a Capcell Pak C18 UG 120 (5 microm, 150x4.6 mm I.D.) column and determined by UV detection at 295 nm. The mobile phase was acetonitrile-0.05 M ammonium acetate (50:50), and the flow-rate was 0.8 ml/min at 40 degrees C. The mean recoveries (n=4) were 89.1-95.0% with a relative standard deviation of 1.1-2.6%. The detection limits were 0.004-0.006 microg/g in milk. The proposed method was used to monitor raw milk samples for the market, and applied to the analysis of milk samples from 10 cows which had been administered with triclabendazole to control the liver fluke. The confirmation of the triclabendazole and its metabolites in the above milk sample has been achieved by electrospray LC-MS for the first time.

Animals↗

PubMed2000

Nitrotyrosine in esophageal squamous cell carcinoma and relevance to p53 expression.

We have examined the expression of nitrotyrosine, a marker of peroxynitrite formation, in 55 esophageal cancers by immunohistochemistry. Nitrotyrosine was detected in 21 of 55 (38.2%) esophageal cancers. Comparison of nitrotyrosine expression and the pathological findings showed that there was a significant association between the expression of nitrotyrosine and each of the depth of tumor invasion (P<0.01), occurrence of metastasis (P<0.05), pathological stage (P<0.01), smoking status (P<0.05) and alcohol intake (P<0.05). The survival rate of patients with nitrotyrosine-negative cancer was significantly higher than that of patients with nitrotyrosine-positive cancer (log-rank test, P<0.01). p53 was detected in 29 of 55 (52.7%) esophageal cancers, however, p53 expression did not correlate with nitrotyrosine expression. In conclusion, nitrotyrosine, a product of nitrogen species, is expressed in esophageal squamous cell carcinoma, which suggests that exogenous risk factors, such as tobacco and alcohol, through NO, are associated with carcinogenesis and progression of esophageal squamous cell carcinoma.

Adult↗

PubMed2000

Atomic and electronic origins of a type- C defect on Si(001)

We present an extensive set of ab initio calculations for a type- C defect on Si(001). Various models belonging to subsurface defects are studied. A substitutional B in the second surface layer is predicted as a possible atomic origin of this defect. However, H and O coupled with second-layer vacancies and a substitutional C are not responsible for a type- C defect. We also discuss how the electronic structure of a type- C defect contributes to its specific scanning tunneling microscopy images.

Journal Article↗

PubMed2000

Lympholeukemia in madai Pagrus major in Japan.

Lympholeukemia has been occurring to an epizootic extent with mass mortality in 1 and 2 yr old madai (= Japanese red sea bream) Pagrus major in the winter season (October-May) in the western regions of Japan since 1975. Diseased fish displayed severe anemia and markedly increased numbers of neoplastic lymphocytoid and lymphoblastoid cells in the blood. Neoplastic cells originated in the splenic lymphatic cells and systemically caused severe metastatic lesions in the heart, liver, kidney, digestive tracts, gills and the lateral musculature. Electron microscopy revealed adeno-like viral particles (78 to 83 nm in diameter) in the nucleus of lymphoblastoid cells which appeared in the early prevalent stage but no viral particles in the lymphocytoid cells or plasmacytoid cells, which subsequently increased in number. In this paper, we describe light and electron microscopic features of neoplasms and neoplastic cells.

Animals↗

PubMed2000

Pathological changes caused by cold-water stress in Japanese eel Anguilla japonica.

In the present study, histopathological changes in Japanese eel Anguilla japonica subjected to 'cold-water stress' were examined. Eels were exposed to cold water (13 to 15 degrees C) and warmer water (25 degrees C) as controls. Fish held in warm water did not show any apparent changes. Although none of the eels exposed to cold water died, they displayed nephrotic changes such as cloudy swelling and hyaline droplet degeneration of the renal tubular epithelia. Fish with nephroses had low levels of serum chloride (12 to 23 mg l-1 in fish with hyaline droplet degeneration, 71 to 81 mg l-1 in fish with cloudy swelling) compared with the control fish (87 to 109 mg l-1). In electron microscopy, affected tubular cells had variously damaged mitochondria and formations of secondary lysosomes of variable sizes. Electron microscopy also revealed mitochondrial degeneration in hepatocytes and degenerated granules of neutrophils in the hematopoietic tissue. 'Cold-water stress' was effective in damaging Japanese eels below 15 degrees C.

Anguilla↗

PubMed2000

Viremia-associated ana-aki-byo, a new viral disease in color carp Cyprinus carpio in Japan.

A new virus disease that displays dermal ulceration and high mortality has been occurring since 1996 in color carp Cyprinus carpio reared in warm water in Japan. In histological examinations, initial erosive lesions displayed necrosis, hemorrhage and fibrin deposition in the dermal loose connective tissue and were accompanied by the partial destruction of the epidermis. Developed ulcerative lesions involved the lateral musculature with bacterial invasions. In visceral organs, necrotic cells were observed in the hematopoietic tissue, the spleen and the intestinal tissues as well as in cardiac muscle fibers which showed no signs of bacterial invasion. Electron microscopy revealed corona-like virus particles in these necrotic cells. The necrotic cells of the hematopoietic tissue and the spleen were accompanied by the formation of tubular structures and crystalline inclusions. The putative virus was isolated and cultured in epithelioma papillosum cyprini (EPC) cells. Carp experimentally inoculated with the cultured virus showed virus transmission, and the same pathological signs of the disease and mortalities as in natural infections.

Animals↗

PubMed2000

Reciprocal role of ERK and NF-kappaB pathways in survival and activation of osteoclasts.

To examine the role of mitogen-activated protein kinase and nuclear factor kappa B (NF-kappaB) pathways on osteoclast survival and activation, we constructed adenovirus vectors carrying various mutants of signaling molecules: dominant negative Ras (Ras(DN)), constitutively active MEK1 (MEK(CA)), dominant negative IkappaB kinase 2 (IKK(DN)), and constitutively active IKK2 (IKK(CA)). Inhibiting ERK activity by Ras(DN) overexpression rapidly induced the apoptosis of osteoclast-like cells (OCLs) formed in vitro, whereas ERK activation after the introduction of MEK(CA) remarkably lengthened their survival by preventing spontaneous apoptosis. Neither inhibition nor activation of ERK affected the bone-resorbing activity of OCLs. Inhibition of NF-kappaB pathway with IKK(DN) virus suppressed the pit-forming activity of OCLs and NF-kappaB activation by IKK(CA) expression upregulated it without affecting their survival. Interleukin 1alpha (IL-1alpha) strongly induced ERK activation as well as NF-kappaB activation. Ras(DN) virus partially inhibited ERK activation, and OCL survival promoted by IL-1alpha. Inhibiting NF-kappaB activation by IKK(DN) virus significantly suppressed the pit-forming activity enhanced by IL-1alpha. These results indicate that ERK and NF-kappaB regulate different aspects of osteoclast activation: ERK is responsible for osteoclast survival, whereas NF-kappaB regulates osteoclast activation for bone resorption.

Adenoviridae↗

PubMed2000

c-Myb acetylation at the carboxyl-terminal conserved domain by transcriptional co-activator p300.

Transcription factor c-Myb plays important roles in cell survival and differentiation in immature hematopoietic cells. Here we demonstrate that c-Myb is acetylated at the carboxyl-terminal conserved domain by histone acetyltransferase p300 both in vitro and in vivo. The acetylation sites in vivo have been located at the lysine residues of the conserved domain (K471, K480, K485) by the use of the mutant Myb (Myb-KAmut), in which all three lysine residues are substituted into alanine. Electrophoretic mobility shift assay reveals that Myb-KAmut shows higher DNA binding activity than wild type c-Myb and that acetylation of c-Myb in vitro by p300 causes dramatic increase in DNA binding activity. Accordingly, transactivation activity of both mim-1 and CD34 promoters by Myb-KAmut is higher than that driven by wild type c-Myb. Furthermore, the bromodomain of p300, in addition to the histone acetyltransferase (HAT) domain, is required for effective acetylation of c-Myb, and hGCN5 is revealed to be a factor acetyl-transferase for c-Myb in vitro. We present a new manner of post-translational modification of the c-Myb protein and the potential significance of the acetylation in c-Myb.

Acetylation↗

PubMed2000

Th1 dominance in HAM/TSP and the optico-spinal form of multiple sclerosis versus Th2 dominance in mite antigen-specific IgE myelitis.

To clarify the Th1/Th2 balance in spinal cord inflammation, we used ELISA to measure the total and allergen-specific IgE in 69 patients with clinically definite multiple sclerosis (MS), including 24 patients with the optico-spinal form of MS, 45 with HAM/TSP, 30 HTLV-I carriers without HAM/TSP, 40 patients with acute myelitis, 43 with neurodegenerative disorders, and 42 healthy subjects, and flow cytometry to study the intracellular IFNgamma-positive versus IL-4-positive cell ratio (intracellular IFNgamma/IL-4 ratio) in peripheral blood CD4(+) T cells in 40 patients with MS, including 17 patients with the optico-spinal form of MS, 23 with HAM/TSP, 22 with acute myelitis, 23 with neurodegenerative disorders, and 36 healthy subjects. Patients with HAM/TSP showed a significantly higher intracellular IFNgamma/IL-4 ratio, lower IL-4(+)/IFN-gamma(-) cell percentages, lower total IgE level, and lower frequency of cedar pollen-specific IgE than did the controls. The patients with optico-spinal MS showed a significantly higher intracellular IFNgamma/IL-4 ratio and higher IL-4(-)/IFN-gamma(+) cell percentages than the controls even at remission or in the convalescence phase. In contrast, in the patients with acute myelitis, the total serum IgE level and the frequency of mite antigen-specific IgE were significantly elevated in comparison to the controls, while those having mite antigen-specific IgE myelitis showed a significantly lower IFNgamma/IL-4 ratio in the CD4(+) T cells in comparison to the controls. These findings suggest that the Th1 cell response is predominant in HAM/TSP and optico-spinal MS, whereas the Th2 cell response is predominant in mite antigen-specific IgE myelitis.

Adult↗

PubMed2000

Bonding of alkali- and heat-treated tantalum implants to bone.

Alkali- and heat-treated tantalum (Ta) has been shown to bond to bone. The purpose of this study was to investigate the effects of chemical treatments on the bone-bonding ability of tantalum implants in rabbit tibiae. Miyazaki et al. reported in vitro that alkali- and heat-treated tantalum had an apatite forming ability in an acellular simulated body fluid (SBF). In this study, smooth-surfaced rectangular plates (15 x 10 x 2 mm) of pure tantalum and treated tantalum were prepared. The plates were implanted transcortically into the proximal metaphyses of bilateral rabbit tibiae, alkali- and heat-treated plates for one limb and untreated plates for the contralateral limb, which served as a paired control. Bone bonding at the bone/implant interface was evaluated by tensile testing and undecalcified histological examination, at 8 and 16 weeks after implantation. The treated implants showed weak bonding to bone at 8 weeks, and exhibited significantly higher tensile failure loads compared with untreated tantalum implants at 16 weeks. The untreated implants showed almost no bonding, even at 16 weeks. Histological examination by Giemsa surface staining, contact microradiography (CMR), and scanning electron microscopy (SEM) revealed that treated tantalum implants bonded directly to bone tissue. In contrast, the untreated tantalum implants had a intervening fibrous tissue layer between the bone and the plate and did not bond to bone at 8 and 16 weeks. It is clear from these results that alkali and heat treatment induce the bone-bonding ability of tantalum. This new bioactive tantalum should be an effective material for weight-bearing and bone-bonding orthopedic devices.

Alkalies↗

PubMed2000

Bioactive tantalum metal prepared by NaOH treatment.

Untreated tantalum metal formed an apatite on its surface in simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma. However, it took an induction period as long as 4 weeks for apatite formation. The tantalum metal formed the apatite within 1 week when it was previously soaked in a 0.2 or 0.5M NaOH aqueous solution at 60 degrees C for 24 h to form a sodium tantalate hydrogel layer on its surface. The decrease in the induction period of apatite formation was attributed to the catalytic effect of the Ta-OH groups on the surface of the tantalum metal for apatite nucleation and acceleration of the apatite nucleation by an increased ionic activity product of the apatite in the fluid due to the release of Na(+) ions. The NaOH-treated tantalum metal can form apatite in a short period even in the living body and bond to the bone through this apatite layer. This indicates that a highly bioactive tantalum metal can be obtained by a simple chemical treatment.

Apatites↗

PubMed2000

Genetic dissection of vasculitis in MRL/lpr lupus mice: a novel susceptibility locus involving the CD72c allele.

An MRL/MpJ strain of mice bearing the Fas deletion mutant gene, lpr (MRL/lpr), composed of genomes derived from LG/J, AKR/J, C3H/Di and C57BL/6J mice, develops systemic vasculitis coincidentally with other collagen diseases, but a C3H/HeJ-lpr/lpr (C3H/lpr) strain does not. In a genome-wide screening of the MRL background genes mediating susceptibility to collagen diseases using N2 progeny mice MRL/lpr x (MRL/lpr x C3H/lpr)F1, we previously found that each collagen disease is controlled by a different set of genes. To clarify the candidate genes for vasculitis, we extended the linkage analysis of renal vasculitis to a larger number of N2 mice and to F2 intercross mice. Two distinct recessive susceptibility loci for vasculitis were mapped on chromosome (Chr) 4 at D4Mit89 and D4Mit147 in both progenies. The former was a novel locus for lupus phenotypes, which involved the MRL allele CD72(c) in contrast to the C3H allele CD72(b). The one on Chr 3 was a recessive locus which had an inhibitory effect on vasculitis. From their composition these loci seemed to be derived from AKR/J (for one) and LG/J (for another two) strains, and appeared to act in an additive manner on the development of vasculitis, indicating that vasculitis in MRL/lpr mice is inherited in a polygenic manner.

Alleles↗