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Biomedical subjects

Y Kato

Publications and source records attributed to Y Kato.

At least 91 records · Page 5Linked to original sources
PubMed2002

Multi-slice 3D-CTA - an improvement over single slice helical CTA for cerebral aneurysms.

BACKGROUND AND OBJECTIVE: The aim of this study was to demonstrate the utility of volume rendered multi-slice helical three-dimensional CT angiography in patients with cerebral aneurysm when compared with single slice CT angiography and formal digital subtraction angiography. METHODS: A prototype Toshiba Aquilon multi-slice CT scanner was employed with the following scan conditions: voltage 135 kV; current 300 mA; slice thickness 0.8 mm; scan speed 0.75 sec/cycle; couch speed 1 mm/sec; range 50 mm from foramen magnum; scan pitch 3; three dimensional images were reconstructed using multiple image projections and integral volume rendering algorithms on a Xlink/Xtension workstation. 80 cases of multi-slice CTA for cerebral aneurysm carried out at Fujita University from January 1999 to January 2001 were reviewed. RESULTS: The advantages of multi-slice imaging are illustrated with representative cases of cerebral aneurysm - good demonstration of three dimensional anatomy, appreciation of perforators down to 1 mm in size, delineation of the vessels around the aneurysm complex, relationship between the aneurysm and skull base, information on calcification, thrombus and blebs in the wall and eleven routine views for perusal. CONCLUSION: Multi-slice CTA is a significant improvement over single slice CTA for cerebral aneurysms. It is our experience the superior and precise images produced by multi-slice technology displays anatomical information not readily available from standard DSA. Multislice 3D-CTA is relatively non-invasive and provides better and adequate detail for surgical planning. The basis of multi-slice CT angiography is described. Multi slice CTA is changing the way cerebral aneurysms are being managed nowadays. New advances in the technology of multi-slice CTA resulting in increased image resolution are outlined.

Angiography, Digital Subtraction↗
PubMed2002

Selective nitration of mitochondrial complex I by peroxynitrite: involvement in mitochondria dysfunction and cell death of dopaminergic SH-SY5Y cells.

3-Nitrotyrosine (3-NT) is a specific marker of protein nitration by peroxynitrite (ONOO-) produced from nitric oxide and superoxide. Increase in 3-NT containing protein (3-NT protein) was reported in brains from patients with some neurodegenerative disorders and aging. In this paper, intracellular localization of 3-NT protein was examined in dopaminergic SH-SY5Y cells using the selective antibody against protein-bound 3-NT. 3-NT protein was detected in plasma membrane/nucleus and mitochondria fractions, and interestingly in polypeptide composition of mitochondrial complex I. ONOO--generating SIN-1 induced apoptotic cell death with concomitant increase in 3-NT protein and reduction in mitochondrial ATP synthesis. In addition, an inhibitor of proteasomes, carbobenzoxy-L-isoleucyl-gamma-t-butyl-L-glutamyl-L-alanyl-L-leucinal, enhanced the effects of ONOO-. These results suggest that ONOO- may induce mitochondrial dysfunction and cell death in neurons through nitration of mitochondrial complex I subunits.

Adenosine Triphosphate↗
PubMed2002

The contribution of 2,3,5-trichlorophenyl methyl sulfone, a metabolite of 1,2,4-trichlorobenzene, to the delta-aminolevulinic acid synthetase induction by 1,2,4-trichlorobenzene in rat liver.

In the present study, we investigated the contribution of methylsulfonyl metabolite derived from 1,2,4-trichlorobenzene (1,2,4-TCB) on the delta-aminolevulinic acid (ALA) synthetase induction by the parent compound in rats. The time courses of increasing of hepatic microsomal total cytochrome P450 content after a single i.p. administration of 1,2,4-TCB (1.36 mmol/kg), and 2,3,5- and 2,4,5-trichlorophenyl methyl sulfones (2,3,5- and 2,4,5-TCPSO2Mes) (50 micromol/kg each) were in parallel with those of increasing of the total heme content in liver microsomes. 1,2,4-TCB significantly increased the heme oxygenase activity, but 2,3,5- and 2,4,5-TCPSO2Mes did not. On the other hand, 1,2,4-TCB and 2,3,5-TCPSO2Me markedly enhanced the ALA synthetase activity. No change was observed in this enzyme activity after the administration of 2,4,5-TCPSO2Me. After the administration of 1,2,4-TCB to the rats treated with DL-buthionine-(S,R)-sulfoximine (BSO) and to the non-BSO-treated rats, the concentrations of both 2,3,5- and 2,4,5-TCPSO2Mes were significantly lower in liver of the BSO-treated rats than in liver of the non-BSO-treated rats. Additionally, the 1,2,4-TCB did not elevate the ALA synthetase activity in the BSO-treated rats. On the other hand, the administration of 2,3,5-TCPSO2Me to BSO-treated rats resulted in induction of ALA synthetase. The results strongly suggest that the methyl sulfone derived from 1,2,4-TCB, i.e., 2,3,5-TCPSO2Me, contributes highly to the induction of the ALA synthetase activity by the parent compound.

5-Aminolevulinate Synthetase↗
PubMed2002

Circulating D-dimer and thrombomodulin levels in acute febrile phase of measles.

OBJECTIVES: Circulating D-dimer and thrombomodulin (TM) levels are now routinely measured in clinical laboratories. Plasma levels of D-dimer are used as a marker of fibrin formation and degradation, and serum TM is used to assess the state of endothelial cell injuries. While the levels of circulating D-dimer and TM have been investigated in many diseases, to our knowledge they have not been studied in patients with measles. We measured circulating levels of D-dimer in patients with measles to discuss whether fibrin formation and degradation occur and TM whether endothelial injury occur. METHODS: The plasma levels of D-dimer and serum levels of alanine aminotransferase (ALT) and creatinine were measured of 14 adolescent and adult Japanese patients with measles, and the serum or plasma levels of TM of 10 of these 14 patients were measured in the acute febrile phase and convalescent afebrile phase with commercially available kits. RESULTS: Plasma D-dimer levels were significantly higher in the acute febrile phase than in the convalescent afebrile phase in patients with measles, and no significant difference was shown in serum and plasma TM levels between the two phases. Plasma D-dimer levels were not correlated with serum or plasma TM levels in either phase. No significant differences were identified in the serum ALT and creatinine levels between the acute febrile and convalescent afebrile phases, and the levels of plasma D-dimer were not significantly correlated with the serum ALT levels. CONCLUSIONS: Our results indicate that while clot formation and fibrinolysis may tend to occur in patients with the acute febrile phase of measles, there may be little risk that such patients will suffer endothelial injury.

Acute Disease↗
PubMed2002

Insights into enzyme evolution revealed by the structure of methylaspartate ammonia lyase.

Methylaspartate ammonia lyase (MAL) catalyzes the magnesium-dependent reversible alpha,beta-elimination of ammonia from L-threo-(2S,3S)-3-methylaspartic acid to mesaconic acid. The 1.3 A MAD crystal structure of the dimeric Citrobacter amalonaticus MAL shows that each subunit comprises two domains, one of which adopts the classical TIM barrel fold, with the active site at the C-terminal end of the barrel. Despite very low sequence similarity, the structure of MAL is closely related to those of representative members of the enolase superfamily, indicating that the mechanism of MAL involves the initial abstraction of a proton alpha to the 3-carboxyl of (2S,3S)-3-methylasparic acid to yield an enolic intermediate. This analysis resolves the conflict that had linked MAL to the histidine and phenylalanine ammonia lyase family of enzymes.

Amino Acid Sequence↗
PubMed2002

Airway epithelial cells promote transmigration of eosinophils in a new three-dimensional chemotaxis model.

BACKGROUND: Prominent infiltration of eosinophils in airway mucosa is the pathognomonic sign of asthma. The role of airway epithelial cells in eosinophil infiltration, however, has not been fully elucidated. OBJECTIVE: The aim of this study is to develop a new in vitro transmigration system composed of airway epithelial cells and extracellular matrix, and to investigate the role of airway epithelial cells in eosinophil infiltration. METHODS: A layer of type I collagen gel was formed in Netwell, and BEAS-2B bronchial epithelial cells were cultured on the gel. Then the wells covered with epithelial monolayer were filled with medium, inverted, and new upper chambers were constructed on the gel side by applying a ring cap. After further incubation with or without exogenous cytokines for 48 h, eosinophils or neutrophils were loaded in upper chambers (the gel side) and cells transmigrated to lower chambers (the epithelial cell side) were counted. Immunohistochemical analyses were also performed. RESULTS: While a simple collagen gel hardly promoted eosinophil migration even in the presence of eotaxin or RANTES, significant numbers of eosinophils migrated to lower chambers in the presence of the epithelial cells. Replacement of medium in the lower chamber (the epithelial cell side) with fresh medium, addition of exogenous eotaxin or RANTES in the upper chamber (the gel side), or pre-treatment of eosinophils with anti-CCR3 all inhibited transmigration. We found that the epithelial cells produced and deposited extracellular matrix proteins such as type IV collagen onto the type I collagen gel. Separately, we found that type IV collagen itself was capable of enhancing eotaxin-induced eosinophil migration in a standard chemotaxis assay. Neutrophils also efficiently migrated in the present transmigration system. Pre-treatment of epithelial cells with TNF-alpha and IL-4 enhanced eosinophil transmigration, while that of neutrophils was enhanced by TNF-alpha but suppressed by IL-4. CONCLUSION: By utilizing a new in vitro transmigration system mimicking the airway mucosa, we have demonstrated that airway epithelial cells play an essential role in transmigration of eosinophils and that multiple factors such as chemokines, extracellular matrix proteins and exogenous inflammatory cytokines are involved in efficient transmigration.

Bronchi↗
PubMed2002

Isolation and characterization of Lactococcus piscium strains from vacuum-packaged refrigerated beef.

AIMS: To characterize gram-positive, catalase-negative, psychrotrophic, lactic acid-homofermentative, non-motile cocci isolated from vacuum-packaged refrigerated beef using phenotypic and genotypic methods. METHODS AND RESULTS: A total of 89 strains was isolated at 2 and 6 weeks as one of the predominant microflora of five samples of vacuum-packaged beef stored at 2 degrees C. The strains were compared with reference strains of some gram-positive, catalase-negative cocci using SDS-PAGE whole-cell protein pattern analysis, biochemical characterization and 16S rDNA sequencing. The biochemical and physiological characteristics of the isolates resembled those of Lactococcus piscium GTC 552(T). Numerical analysis of the SDS-PAGE whole-cell protein patterns resulted in close clustering of the strains with L. piscium GTC 552(T) (r > 0.68). Other Lactococcus and Leuconostoc species could be distinguished from the isolates using SDS-PAGE whole-cell protein patterns (r < 0.58) and biochemical characteristics. The 16S rDNA sequencing of four randomly selected strains showed that the strains differed from L. piscium GTC 552(T) by two to three bases in the highly variable region of the sequence. This is the first report on the isolation of L. piscium from vacuum-packaged beef. CONCLUSIONS: The gram-positive catalase-negative cocci isolated from vacuum-packaged refrigerated beef have been identified as L. piscium. SIGNIFICANCE AND IMPACT OF THE STUDY: The findings of this work contribute to the knowledge of the microflora of vacuum-packaged refrigerated beef.

Animals↗
PubMed2002

Full-length sequence and functional analysis of hepatitis B virus genome in a virus carrier: a case report suggesting the impact of pre-S and core promoter mutations on the progression of the disease.

In chronic hepatitis B virus (HBV) infection, the quiescent immunotolerant phase evolves into the immunoactive phase. The aim of the present study was to clarify the virological alterations relevant to progression. Serial serum samples obtained from a patient with HBV during long-term follow-up were analysed by sequencing of the full-length HBV-DNA using polymerase chain reaction (PCR). In addition, PCR products of HBV genome from each serum sample were transfected into HuH-7 human hepatoma cells for the functional analysis of the transfected viral genomes. Based on the HBV-DNA sequence analysis, the patient had the genotype C virus, and the mutant HBV with common core promoter mutations (T(1762)A(1764)) and deletion of the pre-S region responsible for large surface protein transcription emerged before the onset of hepatitis. When the vigorous host immune response developed (indicated by the flare-up of hepatitis), the mutant HBV containing common core promoter mutations and another pre-S deletion causing lack of the surface protein promoter became predominant. The HBV-DNA sequences, other than pre-S and core promoter regions were identical to the wild-type sequence throughout the study. Transfection of PCR products containing the mutant HBV sequences resulted in increased amounts of intracellular replicative intermediates but the decreased secretion of HBsAg and HBeAg into culture media, suggesting accumulation of nonenveloped viral core particles within the cells. These results indicate that pre-S deletion and core promoter mutations may participate cooperatively in progression of the disease.

Adult↗
PubMed2002

Recent progress and problems in animal cloning.

It is remarkable that mammalian somatic cell nuclei can form whole individuals if they are transferred to enucleated oocytes. Advancements in nuclear transfer technology can now be applied for genetic improvement and increase of farm animals, rescue of endangered species, and assisted reproduction and tissue engineering in humans. Since July 1998, more than 200 calves have been produced by nuclear transfer of somatic cell nuclei in Japan, but half of them were stillborn or died within several months of parturition. Morphologic abnormalities have also been observed in cloned calves and embryonic stem cell-derived mice. In this review, we discuss the present situation and problems with animal cloning and the possibility for its application to human medicine.

Animals↗
PubMed2002

Age of onset possibly associated with the degree of heteroplasmy in two male siblings with diabetes mellitus having an A to G transition at 3243 of mitochondrial DNA.

We describe two male siblings with diabetes mellitus caused by mitochondrial 3243 mutation. The level of heteroplasmy in peripheral blood leucocytes was determined by a last-cycle hot PCR method. The younger brother, who had 39% heteroplasmy, developed diabetes at age of 25, and demonstrated a lean body habitus and blunted insulin secretion. The elder brother, who had 22% heteroplasmy, was diagnosed at the age of 42. The younger brother showed a higher increment of serum lactate after exercise. In these siblings the level of heteroplasmy in their peripheral blood leucocytes appeared to be associated with age of onset of diabetes.

Adult↗
PubMed2002

Surgical clipping of basilar aneurysms: relationship between the different approaches and the surgical corridors.

BACKGROUND: Surgical clipping for basilar artery aneurysm (BAA) is a technically demanding procedure due to the depth of the surgical field and the presence of vital perforating arteries in the vicinity. The incorporation of various modifications in the conventional approaches has expanded the surgical armamentarium in dealing with these difficult lesions. METHODS AND FINDINGS: 87 patients of BAA were operated at our center, out of which in 48 patients, a pterional transsylvian approach was used. In 12 patients, this approach had to be extended to incorporate the anterior temporal approach in 6 cases, transzygomatic subtemporal approach in 2 cases and transcavernous approach in 4 cases. The surgical indications for the additional approaches and the relationships between the surgical corridors gained by their inclusion were studied. The use of neuroendoscopy facilitated adequate clipping in one case of high BAA without the incorporation of bone drilling, thus opening new surgical corridors. INTERPRETATION: The variable situation of the BAA makes it mandatory for the surgeon to be prepared to simultaneously work through multiple surgical corridors. Neuroendoscopic-assisted microneurosurgery occasionally utilizes a narrow surgical corridor to facilitate BAA clipping using the conventional approaches and eliminates the need to gain access using additional surgical corridors.

Basilar Artery↗
PubMed2002

Successful obliteration of a ruptured partially thrombosed giant m1 fusiform aneurysm with coil embolization at distal m1 after extracranial-intracranial bypass.

Proximal occlusion or trapping combined with EC-IC bypass is usually employed as a definite treatment for a giant fusiform aneurysm in cases where it is impossible to apply clips and do vascular reconstruction. Endovascular treatment is very important as an alternative or combined technique if direct surgery is impossible. The authors report a young male who presented with a 2 nd episode of intracranial bleeding in basal ganglion and subarachnoid hemorrhage with mild right hemiparesis. His 3D-CT scan revealed left ruptured partially thrombosed giant M1 fusiform aneurysm and left unruptured C3 saccular aneurysm. He underwent STA-MCA bypass with attempted M1 reconstruction and a week later attempted total occlusion of the M1 aneurysm with coils. But only a ruptured point at the distal M1 was occluded which, however, resulted in temporary mild right hemiparesis and aphasia. A month later when he was supposed to have his 2 nd coiling procedure his angiogram demonstrated spontaneous and complete obliteration of both the M1 and C3 aneurysms without any new neurological deficit, so no further endovascular procedure was attempted. The discussion is based on this case and previous reports regarding difficult giant M1 fusiform aneurysms, its treatment and spontaneous thrombosis of aneurysmal sac after bypass and distal occlusion. Conclusions are drawn that 1) spontaneous thrombosis of M1 and C3 aneurysms should be the result of hemodynamic alteration in both aneurysms due to a lower flow velocity induced by distal bypass and distal occlusion of M1, 2) combined distal bypass and endovascular obliteration of the aneurysmal sac with coils is a good alternative if vascular reconstruction is difficult or impossible.

Adult↗
PubMed2002

Metabolite of 2,2',4',5-tetrabromobiphenyl, 3-methylsulphonyl-2,2',4',5-tetrabromobiphenyl, a potent inducer of CYP2B1/2 in rat.

1. 3-Methylsulphonyl- and 4-methylsulphonyl-2,2',4',5-tetrabromobiphenyls (3-MeSO(2)- and 4-MeSO(2)-TetraBrBs) were detected in the liver, lung, kidney, adipose tissue and faeces of the 2,2',4',5-tetrabromobiphenyl (TetraBrB)-dosed rat. 2. The administration of 0.05-2.0 micromol kg(-1) doses of 3-MeSO(2)-TetraBrB produced corrresponding increases in the hepatic concentration of the methyl sulphone metabolite, corresponding increases in the content of total cytochrome P450, and corresponding increases in the activities of 7-benzyloxy-, 7-ethoxy- and 7-pentoxyresorufin O-dealkylases. The inducing effects of the 3-MeSO(2)-TetraBrB (0.2 micromol kg(-1)), both on the content of total P450 and on the activities of the three alkoxyresorufin O-dealkylases, were higher than that of the parent TetraBrB (342 micromol kg(-1)). 3. The major phenobarbital (PB)-inducible forms of P450, CYP2B1, CYP2B2, CYP3A2 and CYP2C6, were substantially induced by 3-MeSO(2)-TetraBrB, but CYP1A1 and CYP1A2 were not. On the other hand, the activities of drug-metabolizing enzymes and the four PB-inducible forms of P450 were unchanged by 4-MeSO(2)-TetraBrB treatment. 4. The induction profiles of these enzymes and P450 forms in rat treated with 3-MeSO(2)-TetraBrB were similar to those treated with PB. 5. The inducing ability of 3-MeSO(2)-TetraBrB (0.5 micromol kg(-1)) both on the activities of the three alkoxyresorufin O-dealkylases and on the contents of four PB-inducible forms of P450 was roughly equal to that of PB (431 micromol kg(-1) twice at a 24-h interval) or 3-MeSO(2)-2,2',4',5-tetrachlorobiphenyl (1 micromol kg(-1)). It is noteworthy that the effects of 3-MeSO(2)-TetraBrB on the drug-metabolizing enzymes CYP2B1 and CYP2B2 were several thousand-fold higher than those of parent TetraBrB, while the effect of its isomeric 4-MeSO(2)-TetraBrB were not. 6. The extent of hepatic accumulation of the 3-MeSO(2) metabolite after the administration of TetraBrB (342 micromol kg(-1)) was almost the same as that after the administration of 3-MeSO(2)-TetraBrB (0.1-0.2 micromol kg(-1)). The relationship between the hepatic concentration of the 3-MeSO(2) metabolite and the extent of enzyme induction after the administration of TetraBrB or 3-MeSO(2)-TetraBrB suggests that 3-MeSO(2)-TetraBrB plays an important role in the induction of microsomal drug-metabolizing enzymes by TetraBrB.

Animals↗
PubMed2002

RGD-CAP (betaig-h3) exerts a negative regulatory function on mineralization in the human periodontal ligament.

In our previous studies, RGD-CAP/betaig-h3 was isolated from a fiber-rich fraction of cartilage and was found to have a negative function on mineralization of hypertrophic chondrocytes. However, the expression and biological function of RGD-CAP in the periodontal ligament (PDL) are not known. We hypothesized that RGD-CAP could be expressed in the PDL and regulate its mineralization. To test this, we investigated the expression of RGD-CAP in human PDL and the effects of RGD-CAP on mineralization of cultured PDL cells. RGD-CAP was detected in the human PDL as multimeric proteins greater than 200 kDa. The RGD-CAP mRNA level decreased in cultured PDL cells exposed to 10(-8) M dexamethasone or 10(-8) M 1alpha,25-dihydroxyvitamin D(3) when these steroids increased alkaline phosphatase (ALP) activity. Furthermore, exogenous RGD-CAP suppressed the ALP activity and bone nodule formation of cultured PDL cells. These findings suggest that RGD-CAP in the PDL modulates the mineralization which affects adjacent alveolar bone metabolism.

Alkaline Phosphatase↗
PubMed2002

Effect of enucleation procedures and maturation conditions on the development of nuclear-transferred rabbit oocytes receiving male fibroblast cells.

Enucleated oocytes matured in vitro, from which chromosomes were removed by treatment with ionomycin and demecolcine, were used as recipient oocytes for nuclear transfer of fibroblast cells from a mature male rabbit. The enucleated oocytes with donor nuclei were electrically activated 2 h after fusion. The potential of nuclear-transferred oocytes matured in vitro and ovulated oocytes to develop into blastocysts was high (33-55%), except for oocytes cultured for 8.0 (19%) and 8.5 h (25%) in vitro. After transfer of nuclear-transferred oocytes to recipients, ten of 62 (16%) and one of eight (13%) recipients that received in vitro-matured and ovulated oocytes, respectively, had 19 (1%) and one (0.6%) implantation sites at the time of laparotomy on days 8-17 after transfer. Four fetuses, including two with beating hearts, were obtained on day 15 of gestation after transfer of nuclear-transferred oocytes matured in vitro. The reason for the low efficiency of fetus production was not clear. One possibility is chromosomal abnormalities of nuclear-transferred oocytes, as most (21 of 22) of the oocytes had chromosomes dispersed along the spindle fibre at the first cell cycle. This is the first report of successful production of fetuses after nuclear transfer of rabbit somatic cells.

Animals↗
PubMed2001

Wnt/Frizzled activation of Rho regulates vertebrate gastrulation and requires a novel Formin homology protein Daam1.

Wnt signaling via the Frizzled (Fz) receptor controls cell polarity and movement during development, but the molecular nature of Wnt/Fz polarity signal transduction remains poorly defined. Here we report that in human cells and during Xenopus embryogenesis, Wnt/Fz signaling activates the small GTPase Rho, a key regulator of cytoskeleton architecture. Wnt/Fz activation of Rho requires the cytoplasmic protein Dishevelled (Dvl) and a novel Formin homology protein Daam1. Daam1 binds to both Dvl and Rho, and mediates Wnt-induced Dvl-Rho complex formation. Inhibition or depletion of Daam1 prevents Wnt/Fz activation of Rho and of Xenopus gastrulation, but not of beta-catenin signaling. Our study illustrates a molecular pathway from Wnt/Fz signaling to Rho activation in cell polarity signal transduction.

Adaptor Proteins, Signal Transducing↗