Search PubMed⌕ Search

Biomedical subjects

Y Kitagawa

Publications and source records attributed to Y Kitagawa.

At least 37 records · Page 2Linked to original sources
PubMed2002

Proposed double-layer target for the generation of high-quality laser-accelerated ion beams.

In order to achieve a high-quality, i.e., monoenergetic, intense ion beam, we propose the use of a double-layer target. The first layer, at the target front, consists of high-Z atoms, while the second (rear) layer is a thin coating of low-Z atoms. The generation of high-quality proton beams from the double-layer target, irradiated by an ultraintense laser pulse, is demonstrated with three-dimensional particle-in-cell simulations.

Ions↗
PubMed2002

A novel murine myotonia congenita without molecular defects in the ClC-1 and the SCN4A.

The authors report a new murine model for myotonia congenita designated as B6MT. This line spontaneously arose from breeding of transgenic C57BL/6CrSlc mice, irrelevant of the transgene. The B6MT mouse showed moderate to severe action myotonia, and electromyography revealed myotonic discharge. The phenotype was transmitted with autosomal recessive inheritance. Molecular genetic study of the ClC-1 and the SCN4A genes revealed polymorphism with no functional consequences.

Amino Acid Substitution↗
PubMed2002

Observation of neutron spectrum produced by fast deuterons via ultraintense laser plasma interactions.

We report the first precise spectral measurement of fast neutrons produced in a deuterated plastic target irradiated by an ultraintense sub-picosecond laser pulse. The 500-fs, 50-J, 1054-nm laser pulse was focused on the deuterated polystyrene target with an intensity of 2 x 10(19) W/cm(2). The neutron spectra were observed at 55 degrees and 90 degrees to the rear target normal. The neutron emission was 7 x 10(4) per steradian for each detector. The observed neutron spectra prove the acceleration of deuterons and neutron production by d(d,n)3He reactions in the target. The neutron spectra were compared with Monte Carlo simulation results and the deuteron's directional anisotropy and energy spectrum were studied. We conclude that 2% of the laser energy was converted to deuterons, which has an energy range of 30 keV up to 3 MeV.

Journal Article↗
PubMed2002

Radio-guided sentinel node detection for gastric cancer.

BACKGROUND: Radio-guided detection of sentinel nodes (SNs) has been used to predict regional metastases in patients with malignant melanoma and breast cancer. However, the validity of the SN hypothesis is still controversial for gastrointestinal cancers including gastric cancer. The aim of this study was to test the feasibility and accuracy of radio-guided mapping of SNs for gastric cancer. METHODS: Some 145 consecutive patients with gastric cancer diagnosed as T1 or T2 and evaluated clinically as N0 were enrolled. Endoscopic injection of technetium-99m-radiolabelled tin colloid was performed before operation and radioactive SNs were identified with a gamma probe. Standard radical gastrectomy with lymphadenectomy was performed in all patients and all resected nodes were evaluated by routine histopathological examination. RESULTS: Using radio-guided methods, SNs were detected in 138 (95.2 per cent) of 145 patients. The SN was positive in 22 of 24 patients with lymph node metastasis. The incidence of metastasis in the SNs (7.8 per cent) was significantly higher than that in the non-SNs (0.3 per cent) (P < 0.01). The diagnostic accuracy according to SN status was 98.6 per cent (136 of 138). CONCLUSION: Radio-guided SN mapping is an accurate diagnostic procedure for detecting lymph node metastasis in patients with early-stage gastric cancer.

Chi-Square Distribution↗
PubMed2002

Immunohistochemical localization of CEA, CA19-9 and DU-PAN-2 in hepatitis C virus-infected liver tissues.

AIMS: We investigated expression of CEA, CA19-9 and DU-PAN-2 in liver tissues of chronic hepatitis, liver cirrhosis and hepatocellular carcinoma, measuring their serum value to clarify their clinical significance, and proliferating cell nuclear antigen (PCNA) was assessed in serial sections to determine whether expression of these molecules in chronic liver disease was related to regeneration of biliary ducts. METHODS AND RESULTS: Liver tissues were biopsied under peritoneoscopy or echo-guidance and resected surgically among 63 patients with anti-hepatitis C virus-positive sera. There were 26 cases of chronic hepatitis, 21 cases of liver cirrhosis and 16 cases of hepatocellular carcinoma (four cases of mixed type). They were simultaneously used for immunocytochemistry for CEA, CA19-9 and DU-PAN-2, and PCNA was demonstrated in serial liver tissues by immunohistochemistry. Serum CEA, CA19-9 and DU-PAN-2 were measured by radioimmunoassay or enzyme immunoassay. In chronic hepatitis and liver cirrhosis CEA immunoreactivity was seen on membranes facing bile canaliculi and in bile ductules. Both CA19-9 and DU-PAN-2 immunoreactivity were observed in bile ductules in chronic hepatitis liver cirrhosis and non-neoplastic areas surrounding hepatocellular carcinoma, and CA19-9 was also present in interlobular bile ducts. PCNA immunoreactivity was not detected in marker-positive bile ductules or interlobular bile ducts. In hepatocellular carcinoma CEA immunoreactivity was seen on membrane facing dilated bile canaliculi in glandular structures, and CEA, CA19-9 and DU-PAN-2 immunoreactivity was observed in cholangiolar areas in mixed type of hepatocellular carcinoma. CONCLUSIONS: CEA in chronic hepatitis and liver cirrhosis is expressed not only in bile ductules but also on membrane facing bile canaliculi, and both CA19-9 and DU-PAN-2 were seen in different levels of biliary ducts. These molecules were expressed in bile ductules in surrounding non-neoplastic areas of hepatocellular carcinoma, and their expression was not associated with regeneration of biliary ducts. CEA expression was present in the trabecular type of hepatocellular carcinoma, and CA19-9 and DU-PAN-2 were observed in cholangiolar areas in mixed type of hepatocellular carcinoma.

Antigens, Neoplasm↗
PubMed2002

Inflammatory change in the upper joint space in temporomandibular joint with internal derangement on gadolinium-enhanced MR imaging.

The object of this study was to clarify the relationship between gadopentetate dimeglumine (Gd-DTPA) contrast enhancement of the upper joint space and the severity of internal derangement of the temporomandibular joint (TMJ). Fifty patients with 63 painful TMJs underwent 1.5T MR imaging with T1-weighted images before and after an intravenous injection of Gd-DTPA with or without fat suppression. The relationship was investigated between the contrast enhancement at the upper joint space and disc position, disc morphology or bone morphology. Of the 63 joints, a significant contrast enhancement in the upper joint space was detected in 32 joints. There was a significant high incidence of anterior disc displacement without reduction in the contrast-enhancement positive group compared to the negative group (P = 0.021), but there was no significant difference for disc morphology (P = 0.094) and bone morphology (P = 0.384). Gd-DTPA enhanced MR imaging may potentially have diagnostic value for internal derangements of TMJs.

Adolescent↗
PubMed2001

alpha-, beta- or gamma-chain-specific RNA interference of laminin assembly in Drosophila Kc167 cells.

Drosophila laminin alphabetagamma trimer assembly in Kc167 cells was perturbed by chain-specific RNA interference (RNAi). The intracellular pool of alpha and gamma chains remained unchanged under beta-chain RNAi by lipofection of double-stranded RNA encoding a beta-chain partial sequence. This was also the case for the intracellular pool of alpha and beta chains under gamma-chain-specific RNAi. Nonetheless, the intracellular pool of beta and gamma chains increased markedly under alpha-chain-specific RNAi. Non-reducing SDS/PAGE revealed that some of the increased beta and gamma chains migrated as disulphide-linked betagamma dimers but that the rest migrated as monomers. Since the monomeric beta and gamma bands detected under alpha-chain RNAi were denser than the beta band under gamma-chain RNAi and the gamma band under beta-chain RNAi, respectively, beta and gamma also appeared to accumulate by forming betagamma dimers without the disulphide linkage. We suggest that interconversion of these betagamma dimers is crucial for the replaceable and selective assembly of the alpha chain for alphabetagamma trimer formation.

Animals↗
PubMed2001

A Drosophila haemocyte-specific protein, hemolectin, similar to human von Willebrand factor.

We identified a novel Drosophila protein of approximately 400 kDa, hemolectin (d-Hml), secreted from haemocyte-derived Kc167 cells. Its 11.7 kbp cDNA contains an open reading frame of 3843 amino acid residues, with conserved domains in von Willebrand factor (VWF), coagulation factor V/VIII and complement factors. The d-hml gene is located on the third chromosome (position 70C1-5) and consists of 26 exons. The major part of d-Hml consists of well-known motifs with the organization: CP1-EG1-CP2-EG2-CP3-VD1-VD2-VD'-VD3-VC1-VD"-VD"'-FC1-FC2-VC2-LA1-VD4-VD5-VC3-VB1-VB2-VC4-VC5-CK1 (CP, complement-control protein domain; EG, epidermal-growth-factor-like domain; VB, VC, VD, VWF type B-, C- and D-like domains; VD', VD", VD"', truncated C-terminal VDs; FC, coagulation factor V/VIII type C domain; LA, low-density-lipoprotein-receptor class A domain; CK, cysteine knot domain). The organization of VD1-VD2-VD'-VD3, essential for VWF to be processed by furin, to bind to coagulation factor VIII and to form interchain disulphide linkages, is conserved. The 400 kDa form of d-Hml was sensitive to acidic cleavage near the boundary between VD2 and VD', where the cleavage site of pro-VWF is located. Agarose-gel electrophoresis of metabolically radiolabelled d-Hml suggested that it is secreted from Kc167 cells mainly as dimers. Resembling VWF, 7.9% (305 residues) of cysteine residues on the d-Hml sequence had well-conserved positions in each motif. Coinciding with the development of phagocytic haemocytes, d-hml transcript was detected in late embryos and larvae. Its low-level expression in adult flies was induced by injury at any position on the body.

Amino Acid Sequence↗
PubMed2001

Hypoxic enhancement of type IV collagen secretion accelerates adipose conversion of 3T3-L1 fibroblasts.

Hypoxic modulation of collagen metabolism appears to be related to pathogenesis of many diseases such as fibrosis of connective tissue after injury and scleroderma. Since most of our understanding of how procollagen assembles within the cell has come from studies on cells cultured under normoxia, it may not be helpful for the etiology of the diseases observed in peripheral tissues under hypoxic conditions. As an experimental model for the hypoxic modulation of collagen metabolism, we cultured 3T3-L1 fibroblasts under low partial oxygen pressure and found that hypoxia enhances secretion of type IV collagen 10-fold and accelerates adipose conversion of the cells. The enhanced secretion of type IV collagen was not accompanied by an appreciable increase of alpha1(IV) and alpha2(IV) mRNAs. Prolyl 4-hydroxylase alpha increased only 3-fold under hypoxia. We suggest that hypoxia creates an environment of prolyl 4-hydroxylase alpha(2)beta(2) tetramers favorable for the folding of type IV procollagen which has many interruptions of the Gly-Xaa-Yaa repeat.

3T3 Cells↗
PubMed2001

Inhibition of green tea catechins against the growth of cancerous human colon and hepatic epithelial cells.

The ability of (-)-epicatechin (EC), (-)-epigallocatechin (EGC) and (-)-epigallocatechin gallate (EGCG) to inhibit the growth of HCT 116 colorectal and Hep G2 hepatocellular carcinoma cells was examined by MTT and clonogenic assays (CA). The respective catechins inhibited the growth of HCT 116 more strongly than Hep G2. In MTT assay, IC(50) values of EGC and EGCG against HCT 116 grew smaller on prolongation of the exposure times of the cells to the catechins. In CA, however, these two catechins had IC(50) values ranging between 7.6+/-0.4 and 11.2+/-0.5 microM against the same cells regardless of the exposure times. EC showed much weaker growth inhibitions relative to the two aforementioned catechins.

Beverages↗
PubMed2001

Suppression of the transcriptional activity and DNA binding of nuclear factor-kappa B by a paraneoplastic cerebellar degeneration-associated antigen.

Paraneoplastic cerebellar degeneration (PCD) associated with gynecological malignancies is a disorder in which an autoimmune mechanism has been suggested, and both antibody- and cell-mediated immune responses exist against pcd17/cdr2, a neural protein expressed in cerebellar Purkinje neurons and brainstem neurons. In this report, we describe that pcd17 can suppress the basal or activated NF-kappaB-dependent transcriptional activity in a co-transfection study. The DNA binding of constitutive NF-kappaB complexes decreased in the nucleus of TNF-alpha-stimulated neuroblastoma cells, though pcd17 does not bind to classical NF-kappaB consensus site. These data indicate that pcd17 is a potential repressor for NF-kappaB-dependent gene transcription in neurons.

Animals↗
PubMed2001

Fast heating of ultrahigh-density plasma as a step towards laser fusion ignition.

Modern high-power lasers can generate extreme states of matter that are relevant to astrophysics, equation-of-state studies and fusion energy research. Laser-driven implosions of spherical polymer shells have, for example, achieved an increase in density of 1,000 times relative to the solid state. These densities are large enough to enable controlled fusion, but to achieve energy gain a small volume of compressed fuel (known as the 'spark') must be heated to temperatures of about 108 K (corresponding to thermal energies in excess of 10 keV). In the conventional approach to controlled fusion, the spark is both produced and heated by accurately timed shock waves, but this process requires both precise implosion symmetry and a very large drive energy. In principle, these requirements can be significantly relaxed by performing the compression and fast heating separately; however, this 'fast ignitor' approach also suffers drawbacks, such as propagation losses and deflection of the ultra-intense laser pulse by the plasma surrounding the compressed fuel. Here we employ a new compression geometry that eliminates these problems; we combine production of compressed matter in a laser-driven implosion with picosecond-fast heating by a laser pulse timed to coincide with the peak compression. Our approach therefore permits efficient compression and heating to be carried out simultaneously, providing a route to efficient fusion energy production.

Journal Article↗
PubMed2001

Inhibitory effects of 6-O-acylated L-ascorbic acids possessing a straight- or branched-acyl chain on Epstein-Barr virus activation.

6-O-Acylated L-ascorbic acids possessing a straight- or branched-acyl chain of varying length from C(4) to C(18) have been synthesized and evaluated their anti-tumor promoting effects on the activation of the Epstein-Barr virus early antigen. The derivatives having a straight- or branched-acyl chain of C(6) to C(11) carbon atoms exhibited marked effects.

Anticarcinogenic Agents↗
PubMed2001

Drosophila mitochondrial transcription factor A (d-TFAM) is dispensable for the transcription of mitochondrial DNA in Kc167 cells.

We have cloned cDNA encoding Drosophila mitochondrial (mt) transcription factor A (d-TFAM). RNA interference (RNAi) of d-TFAM by lipofection of haemocyte-derived Kc167 cells with double-stranded RNA reduced d-TFAM to less than 5% of the normal level. Reflecting the ability of TFAM to stabilize mtDNA, RNAi of d-TFAM reduced mtDNA to 40%. Nonetheless, transcription of the ND2 and ND5 genes and their mRNAs remained unchanged for 8 days of the duration of RNAi. We thus show that d-TFAM is not essential for the transcription of Drosophila mtDNA.

Amino Acid Sequence↗
PubMed2001

Induction of major histocompatibility complex class I molecules on human neuroblastoma line cells by a flavoid antioxidant.

Human major histocompatibility complex (MHC) class I expression is usually suppressed in neuronal cells and neuroblastoma cells. In the present study, we analyzed the effect of a flavonoid antioxidant, silymarin, on the induction of MHC class I molecules in human neuroblastoma line cells. Treatment of neuroblastoma cells with silymarin resulted in the expression of MHC class I molecules. Silymarin treatment enhanced the transcriptional activity of the reporter construct containing MHC class I promoter truncated within -428 bp of transcription initiation, but not the construct containing the promoter truncated within -284 bp. Because an E-box element is located between -428 and -285 bp of the transcription initiation, results suggest that silymarin acts on the enhancer activity of the E-box in the MHC class I promoter. Our findings indicate that silymarin induces the transcriptional factors to enhance the MHC class I promoter through the class I E-box element.

Antioxidants↗
PubMed2001

Defect in SHAP-hyaluronan complex causes severe female infertility. A study by inactivation of the bikunin gene in mice.

Hyaluronan (HA) associates with proteins and proteoglycans to form the extracellular HA-rich matrices that significantly affect cellular behaviors. So far, only the heavy chains of the plasma inter-alpha-trypsin inhibitor (ITI) family, designated as SHAPs (serum-derived hyaluronan-associated proteins), have been shown to bind covalently to HA. The physiological significance of such a unique covalent complex has been unknown but is of great interest, because HA and the ITI family are abundant in tissues and in plasma, respectively, and the SHAP-HA complex is formed wherever HA meets plasma. We abolished the formation of the SHAP-HA complex in mice by targeting the gene of bikunin, the light chain of the ITI family members, which is essential for their biosynthesis. As a consequence, the cumulus oophorus, an investing structure unique to the oocyte of higher mammals, had a defect in forming the extracellular HA-rich matrix during expansion. The ovulated oocytes were completely devoid of matrix and were unfertilized, leading to severe female infertility. Intraperitoneal administration of ITI, accompanied by the formation of the SHAP-HA complex, fully rescued the defects. We conclude that the SHAP-HA complex is a major component of the HA-rich matrix of the cumulus oophorus and is essential for fertilization in vivo.

Alpha-Globulins↗