Biomedical subjects

K Shimizu

Publications and source records attributed to K Shimizu.

At least 253 records · Page 14Linked to original sources

PubMed2000

Glibenclamide enhances cortical spreading depression-associated hyperemia in the rat.

We investigated the contribution of ATP-sensitive potassium channels (K(ATP)) and calcium-activated potassium channels (Kca2+) to cortical spreading depression (CSD)-associated hyperemia using the rat closed cranial window model. The peak CBF response was enhanced by 12 +/- 5, 13 +/- 4, and 28 +/- 8% (p<0.01) of the control with 10(-6), 10(-5) and 10(-4) mol/l glibenclamide (glyb), a K(ATP) antagonist, respectively. We also calculated the area under the CBF curve to fully represent the extent of hyperemia during CSD. The area increased by 30 +/- 8 (p<0.05), 72 +/- 31 (p<0.05) and 88 +/- 20% (p<0.05) of the control with 10(-6), 10(-5) and 10(-4) mol/l glyb, respectively. However, charybdotoxin (CTX), a Kca2+ antagonist showed no effect. The effect of glyb was inhibited by pretreatment with 5 mg/kg indomethacin. We conclude that activation of K(ATP), perhaps associated with neurons, plays an inhibitory role in the CSD-associated hyperemia via an indomethacin-sensitive mechanism.

Animals↗

PubMed2000

AML1-MTG8 leukemic protein induces the expression of granulocyte colony-stimulating factor (G-CSF) receptor through the up-regulation of CCAAT/enhancer binding protein epsilon.

The t(8;21) translocation is one of the most frequent chromosomal abnormalities associated with acute myeloid leukemia (AML). In this translocation, the AML1 (CBFA2/PEBP2aB) gene is disrupted and fused to the MTG8 (ETO) gene. The ectopic expression of the resulting AML1-MTG8 fusion gene product in L-G and 32Dcl3 murine myeloid precursor cells stimulates cell proliferation without inducing morphologic terminal differentiation into mature granulocytes in response to granulocyte-colony stimulating factor (G-CSF). This study found that the ectopic expression of AML1-MTG8 elevates the expression of the G-CSF receptor (G-CSFR). Analysis of the promoter region of the G-CSFR gene revealed that up-regulation of G-CSFR expression by AML1-MTG8 does not depend on the AML1-binding sequence, but on the C/EBP (CCAAT/enhancer binding protein) binding site. The results suggest that the overproduction of G-CSFR is at least partly mediated by C/EBPepsilon, whose expression is activated by AML1-MTG8. The ectopic expression of G-CSFR in L-G cells induced cell proliferation in response to G-CSF, but did not inhibit cell differentiation into mature neutrophils. Overexpression of C/EBPepsilon in L-G cells also stimulated G-CSF-dependent cell proliferation. High expression levels of G-CSFR were also found in the leukemic cells of AML patients with t(8;21). Therefore, G-CSF-dependent cell proliferation of myeloid precursor cells may be implicated in leukemogenesis.

Animals↗

PubMed2000

Inhibition of CD40 signaling limits evolution of established atherosclerosis in mice.

Interruption of inflammatory pathways may provide a novel approach to the therapy of atherosclerosis. Recently, we and others have implicated the immune mediator dyad CD40/CD40L (CD40 ligand), which is expressed on endothelial and smooth muscle cells, macrophages, and T lymphocytes within human atherosclerotic lesions, in aspects of atherogenesis and the acute coronary syndromes, including regulation of matrix metalloproteinases, procoagulant activity, cytokines, etc. In vivo, interruption of CD40 signaling reduced the initiation and early phases of atheroma formation in hypercholesterolemic mice. However, whether interruption of CD40 signaling can retard the progression or even regress established lesions remains unknown. We report here that anti-CD40L antibody treatment of randomly assigned low-density lipoprotein receptor-deficient mice during the second half of a 26-week regimen of high-cholesterol diet did not regress, but did significantly reduce further evolution of established atherosclerotic lesions within the aortic arch and particularly the thoracic and abdominal aorta, as compared with control treatment (application of rat-IgG or saline; 13 weeks, continued high-cholesterol diet). In addition to limiting lesion progression, anti-CD40L treatment changed the composition of atheroma in manners thought to favor plaque stability, e.g., reduced relative content of macrophages and lipid, as well as increased relative content of smooth muscle cells and collagen. These data implicate CD40/CD40L as crucial mediators not only in the initial events of atherogenesis but also during the evolution of established atheroma. This study lends further support to the importance of this specific inflammatory signaling pathway in atherosclerosis and its complications.

Animals↗

PubMed2000

Genomic structure of the human ING1 gene and tumor-specific mutations detected in head and neck squamous cell carcinomas.

We characterized the genomic structure of the human ING1 gene, a candidate tumor suppressor gene, and found that the gene has three exons. We also demonstrated that four mRNA variants were transcribed from three different promoter regions. Of 34 informative cases of head and neck squamous cell carcinoma, 68% of tumors showed loss of heterozygosity at chromosome 13q33-34, where the ING1 gene is located. Here we present the first report that three missense mutations and three silent changes were detected in the ING1 gene in 6 of 23 tumors with allelic loss at the 13q33-34 region. These missense mutations were found within the PHD finger domain and nuclear localization motif in ING1 protein, probably abrogating the normal function.

Carcinoma, Squamous Cell↗

PubMed2000

Structure of the human retinoblastoma-related p107 gene and its intragenic deletion in a B-cell lymphoma cell line.

The human p107 protein shares many structural and functional features with the retinoblastoma gene product and retinoblastoma-related p130 protein. In this study, we have cloned and elucidated the complete intron-exon organization of the gene encoding the p107 protein. The gene contains 22 exons spanning over 100kilobase pairs of genomic DNA. The length of individual exons ranges from 50 to 840base pairs. The arrays of exons in the p107 gene are rather similar among members of the gene family, especially to those of the p130 gene, while the length of introns is extensively diverse. This study will provide a molecular basis for implementing comprehensive screening for p107 mutations using genomic DNAs from human malignancies. We also show a detailed structure of an intragenic deletion of the p107 gene found in a human B-cell lymphoma cell line, KAL-1, which was shown to occur by homologous recombination between the two directly repeated Alu family sequences.

Base Sequence↗

PubMed2000

Molecular cloning of a novel NF2/ERM/4.1 superfamily gene, ehm2, that is expressed in high-metastatic K1735 murine melanoma cells.

We have cloned a novel gene, Ehm2, that is expressed in high-metastatic but not in low-metastatic K-1735 murine melanoma cells. The Ehm2 gene encodes a protein of 527 amino acid residues, showing up to 41% amino acid identity with the FERM domain of NF2/ERM/4.1 superfamily proteins, which have the function of connecting cell surface transmembrane proteins to cytoskeletal molecules. The Ehm2 gene was mapped to chromosome 4 and was expressed in the liver, lung, kidney, and testis and in 7- to 17-day embryos. The highest level of homology was observed with NBL4, which is a new subfamily protein of the NF2/ERM/4.1 superfamily. A human homologue of the mouse Ehm2 gene, showing significant homology (83% identity), was identified in the genomic DNA and EST databases. Furthermore, seven rat EST clones and one pig EST clone in the GenBank EST database were identified as having 83-92% sequence homology with the cDNA sequence of the mouse Ehm2 gene. Thus, Ehm2 is a highly conserved gene that encodes a novel member of the NF2/ERM/4.1 superfamily proteins.

Animals↗

PubMed2000

Suppression of tumor angiogenesis and growth by gene transfer of a soluble form of vascular endothelial growth factor receptor into a remote organ.

Antiangiogenic therapy shows promise as a strategy for cancer treatment. We constructed an adenovirus (AdVEGF-ExR) expressing the entire extracellular domain of the human vascular endothelial growth factor (VEGF) receptor (flt-1) fused to the Fc portion of human IgG. The soluble receptor secreted from AdVEGF-ExR-infected cells bound to VEGF and inhibited VEGF-induced DNA synthesis in endothelial cells. When human lung cancer cell line H157, which produces not only VEGF but also fibroblast growth factor 2 and interleukin 8 at substantial levels, was infected with AdVEGF-ExR, cell growth in vitro was not affected. However, when H157 cells infected with AdVEGF-ExR were injected s.c. into nude mice, tumor formation stopped on the 10th day after reaching a certain size (about 100 mm3), and tumor size declined gradually thereafter. When AdVEGF-ExR was injected into skeletal muscle and uninfected H157 cells were injected s.c., the soluble receptor was detectable in the circulating blood for 3 weeks, tumor growth ceased after 10 days, and tumor size declined thereafter. Histological examination revealed that intratumor angiogenesis was markedly suppressed, and apoptosis was enhanced. Using the same experimental protocol, a significant suppression of tumor growth was also seen in four of five other lung cancer cell lines, some of which secreted VEGF at nominal levels, at least under normoxic conditions in vitro. Our results demonstrate that adenovirus-mediated expression of a soluble VEGF receptor in a remote organ could inhibit tumor angiogenesis and enhance apoptosis and thereby suppress tumor growth in vivo. Adenovirus-mediated overexpression of a soluble VEGF receptor in a remote organ may have the potential to be a feasible and effective strategy for cancer treatment.

Adenoviruses, Human↗

PubMed2000

Characteristics of induced spreading depression after transient focal ischemia in the rat.

We examined characteristics of spreading depression (SD) induced on the rat cortex 1 day after transient focal ischemia. Male Wistar rats (n=21) were subjected to transient intraluminal thread occlusion of the right middle cerebral artery for 75 min. Twenty-four hours after the reperfusion, cerebral blood flow (CBF) was determined using laser Doppler flowmeter during multiple SDs elicited on both non-stroke (left) and stroke (right) cortex by the topical application of 2 M KCl. We also examined CBF responses before and after the intravenous administration of the nonspecific NOS inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg) in normal and stroke cortex. Animals were divided into two groups; Group 1 (n=12), animals with subcortical infarction and Group 2 (n=9), animals with subcortical plus cortical infarction. There were no differences between non-stroke and stroke sides in the duration or amplitude of the DC potential shifts in either group. The transient CBF hyperemia during SD was not different between non-stroke (372+/-23% of baseline, mean+/-S.E.) and stroke sides (383+/-30%) in Group 1. However, in Group 2, CBF was significantly restricted on the stroke side (192+/-15% vs. non-stroke side, 374+/-33%). In four normal animals without ischemia, there were no differences in CBF response between both sides. L-NAME had no effect on the transient CBF hyperemia during SD in any of the groups. These data suggest that the CBF responses during SD in the peri-infarction area is restricted 1 day after the transient focal ischemia, while CBF responses are intact in normal cortex overlapping a subcortical infarct. Further, our results indicate that nitric oxide does not promote CBF responses during SD in normal cortex or in tissue surrounding infarction.

Animals↗

PubMed2000

Alteration of beta-catenin expression in esophageal squamous-cell carcinoma.

beta-catenin regulates cadherin-mediated cell-cell adhesion and also functions as a signaling molecule. In this study, we examined the expression pattern of E-cadherin, alpha-catenin and beta-catenin in 22 cases of esophageal squamous-cell carcinoma by Western-blot analysis. Expression of E-cadherin, alpha-catenin and beta-catenin was lower in carcinomas than in normal esophageal mucosa in 4 cases (18.2%) for E-cadherin, 6 cases (27.3%) for alpha-catenin and 9 cases (40.9%) for beta-catenin. Expression of beta-catenin was not always correlated with that of E-cadherin. Over-expression of beta-catenin was observed in 3 cases (13.6%). Of 3 cases that presented with over-expression of beta-catenin, 2 showed cytoplasmic staining by immunohistochemistry. Nuclear localization of beta-catenin was observed in one case that had higher beta-catenin level in tumor tissue (1.4-fold higher than normal mucosa). The genomic DNA sequences of the beta-catenin and the APC gene were analyzed. No mutation of the beta-catenin gene was observed in any cases. Silent mutation of the APC gene was found in all the cases that showed over-expression or nuclear localization of the beta-catenin protein. These results indicate that alterations of the cadherin-catenin complex may play an important role in a sub-set of esophageal carcinogenesis. Furthermore, it is suggested that beta-catenin over-expression is not caused by genetic alteration of either the beta-catenin or the APC gene.

Blotting, Western↗

PubMed2000

p38 mitogen-activated protein kinase and c-jun-NH2-terminal kinase regulate RANTES production by influenza virus-infected human bronchial epithelial cells.

Airway epithelial cells which are the initial site of influenza virus (IV) infection are suggested to participate in airway inflammatory response by expressing various cytokines including RANTES; however, the intracellular signal that regulates RANTES expression has not been determined. In the present study, we examined the role of p38 mitogen-activated protein (MAP) kinase, extracellular signal-regulated kinase (Erk), and c-Jun-NH2-terminal kinase (JNK) in RANTES production by IV-infected human bronchial epithelial cells. The results showed that IV infection induced increases in p38 MAP kinase, and Erk and JNK phosphorylation and activity. SB 203580, PD 98059, and CEP-1347 attenuated IV-infection induced p38 MAP kinase activity, Erk activity, and JNK activity, respectively. SB 203580 and CEP-1347 attenuated RANTES production by 45.3% and 45.2%, respectively, but a combination of these inhibitors additively attenuated by 69.1%. In contrast, PD 98059 did not attenuate. Anti-IL-1alpha mAb, anti-IL-1beta mAb, anti-TNF-alpha mAb, anti-IL-8 mAb, anti-IFN-beta mAb, anti-RANTES mAb, and a combination of these mAbs did not affect IV infection-induced increases in p38 MAP kinase, Erk, and JNK phosphorylation, indicating that each cytokine neutralized by corresponding Ab was not involved in IV infection-induced phosphorylation of MAP kinases. N-acetylcysteine (NAC) did not affect IV infection-induced increases in MAP kinase phosphorylation, whereas NAC attenuated RANTES production by 18.2%, indicating that reactive oxygen species may act as a second messenger leading to RANTES production via p38 MAP kinase- and JNK-independent pathway. These results indicate that p38 MAP kinase and JNK, at least in part, regulate RANTES production by bronchial epithelial cells.

Acetylcysteine↗

PubMed2000

Activation of immediate early gene, c-fos, and c-jun in the rat small intestine after ischemia/reperfusion.

BACKGROUND: Activated immediate early genes (IEGs) play key roles in mediating cellular response after ischemia/reperfusion (I/R) injuries in some organs such as liver, heart and kidney. However, there is no report investigating an association between the activation of IEGs and cellular regeneration or programmed cell death after I/R in small intestine. METHODS: We examined a sequential expression of c-fos and c-jun after I/R in rat small intestine using reverse transcription-polymerase chain reaction and Northern blot analysis, and compared the patterns with coexistent two parameters: (1) regeneration determined by immunohistochemical detection of proliferating cell nuclear antigen, (2) programmed cell death determined with the terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end-labeling (TUNEL) method and DNA fragmentation. RESULTS: The expression of c-fos and c-jun mRNA increased markedly 15 min after reperfusion and was, respectively, 6.3 and 4.4 times higher than in controls. Proliferating cell nuclear antigen expression was significantly elevated between 5 min and 4 hr, peaking at 30 min after reperfusion. Apoptosis showed a peak 60 min after reperfusion. Apoptosis after I/R was detected in the nuclei of absorptive epithelial cells by the TUNEL method, and these apoptotic signals were consistent with the expression of c-Fos and c-Jun proteins using an immunohistochemical method. CONCLUSIONS: These results suggest that overexpression of c-fos and c-jun after I/R in the small intestine correlates with programmed cell death and subsequent cellular regeneration.

Animals↗

PubMed2000

Infrared intensity and morphology of l-monolaurin-water systems.

The infrared spectra for some metastable states in 1-monolaurin water systems were observed at room temperature, where the relative intensity of bands due to paraffin chains changed considerably, especially in the CH2 rockings, which disappear in some cases. It is considered that the spectral changes result from the morphology change on going from the crystal to the liquid crystal, smectic B phase, so-called gel phase, which consists of the lipid bilayers with ordered paraffin chains alternating with water layers. The model for explaining the intensity change is proposed on the basis of the interaction among oscillating dipoles.

Glycerides↗

PubMed2000

Somatic mutations and genetic polymorphisms of the PPP1R3 gene in patients with several types of cancers.

Recently, we found nonsense and missense mutations of the PPP1R3 (protein phosphatase 1, regulatory subunit 3) gene in diverse human cancer cell lines and primary lung carcinomas, indicating that PPP1R3 functions as a tumor suppressor in human carcinogenesis. In this study, to assess the prevalence of PPP1R3 mutations in human primary cancers and the genetic diversity of the PPP1R3 gene in the human population, somatic mutations and genetic polymorphisms in the PPP1R3 gene were examined in 137 pairs of cancerous and non-cancerous tissues of patients with cancers of colon, ovary, and liver. Five somatic mutations including two missense mutations were detected in three cancerous tissues consisting of two colorectal carcinomas and one ovarian carcinoma. Five novel single nucleotide polymorphisms (SNPs) associated with the substitution of amino acids were also identified in cancer patients, in addition to five known nonsynonymous SNPs, including three previously reported ones as having an impact on the susceptibility to insulin resistant disorders. Differences in the activities and properties of multiple PPP1R3 proteins, which are produced in human cells due to variable somatic mutations and genetic polymorphisms in the PPP1R3 gene, can be involved in human carcinogenesis and susceptibility to diseases.

Amino Acid Substitution↗

PubMed2000

Absence of p51 mutation in human hepatocellular carcinoma.

The p51 gene encodes a protein with significant homology to p53. To investigate the involvement of the p51 gene in human hepatocarcinogenesis, mutation analysis of the p51 gene was performed in 54 cases of hepatocellular carcinoma (HCC). No mutations causing amino acid substitutions or frameshifts were found by polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) analysis of the entire coding region. The result indicated that mutation of the p51 gene does not play a major role in the development of HCC in Japanese patients. Further studies on p51 expression and its functions, including the interaction with p53, are necessary to elucidate the role of the p51 gene in human hepatocarcinogenesis.

Carcinoma, Hepatocellular↗

PubMed2000

The interspinous ligament of the lumbar spine. Magnetic resonance images and their clinical significance.

STUDY DESIGN: A preliminary study of magnetic resonance features of the interspinous ligament in degenerative lumbar spine. OBJECTIVES: To classify the magnetic resonance imaging features of the interspinous ligaments in relation to the patient's age, disc degeneration, and radiographic instability. Magnetic resonance imaging also was correlated with the histologic findings of the interspinous ligaments. SUMMARY OF BACKGROUND DATA: As reported, rupture of the interspinous ligament frequently is found in the degenerative lumbar spine. However, little information is available in the literature on imaging assessment of the interspinous ligament in degenerative lumbar disorders. METHODS: In this study, 24 interspinous ligaments at L1-L2 or L2-L3 from 15 patients with nondegenerated discs were selected to represent normal magnetic resonance features of the interspinous ligament, and 38 patients with the mean age of 49 years underwent functional radiography and magnetic resonance imaging. The magnetic resonance features of the interspinous ligament were classified into five categories according to their signal intensities: Type 1A (low intensity on T1- and T2-weighted images without hypertrophy of the spinal process); Type 1B (same signal pattern as in Type 1A with hypertrophy of spinal process); Type 2 (low intensity on T1- and high intensity on T2-weighted images); Type 3 (high intensity on T1-weighted images); and Type 4 (others). Seven patients with variable patterns of the interspinous ligament were selected to undergo histologic examinations. RESULTS: Of the interspinous ligaments considered normal, 80% were classified as Type 1A. There were 14 Type 1A, 30 Type 1B, 19 Type 2, 16 Type 3, and 20 Type 4 ligaments. The mean age and disc degeneration grade of the patients with the Type 1B ligaments was significantly higher. Instability was found to be associated with Type 2 interspinous ligaments (7 of 19), whereas instability rarely was noted in Types 1A (1 of 14) and 1B (1 of 30) ligaments. The histologic examination revealed that chondrometaplasia and necrotization of fiber bundle predominated in Type 1B, proliferation of cells and vascular invasion in Type 2, fatty degeneration in Type 3 ligaments. CONCLUSIONS: The magnetic resonance imaging characteristics may be helpful in assessing normal or pathologic changes in the interspinous ligaments.

Adolescent↗

PubMed2000

A giant cell angiofibroma involving 6q.

Giant cell angiofibroma, a recently proposed new clinicopathological entity, arises exclusively in the orbit in adults and histologically exhibits features intermediate between those of giant cell fibroblastoma and solitary fibrous tumor. In a typical case of giant cell angiofibroma, abnormalities of chromosome 6 with a common pattern involving 6q13 were detected together with various other chromosomal aberrations. To our knowledge, this is the first reported case of giant cell angiofibroma demonstrating chromosomal abnormalities.

Angiofibroma↗

PubMed2000

A soluble transforming growth factor beta receptor expressed in muscle prevents liver fibrogenesis and dysfunction in rats.

We demonstrated that local expression of a dominant-negative type II TGF-beta receptor prevents live fibrogenesis and dysfunction in dimethylnitrosamine-treated rats. Using the same model, we have now tested whether a soluble TGF-beta receptor expressed in skeletal muscle can effectively suppress TGF-beta signaling in a remote organ (the liver). We constructed an adenovirus expressing an entire ectodomain of human TGF-beta type II receptor fused to the Fc portion of human IgG (AdTbeta-ExR). This soluble receptor secreted from AdTbeta-ExR-infected cells bound TGF-beta and blocked TGF-beta-signaling in vitro. After intramuscular injection of AdTbeta-ExR in rats, the soluble receptor protein was detectable in the blood for at least 3 weeks. When such rats were treated with dimethylnitrosamine, liver fibrosis was markedly attenuated without apparent systemic or local side effects. The hepatic hydroxyproline content was reduced to a level indistinguishable from that achieved by local expression of the dominant-negative TGF-beta receptor. Since a qualitatively and quantitatively similar suppression was achieved by the two methods, it may be concluded that the new strategy can achieve a complete inhibition of TGF-beta signaling under pathophysiological conditions in vivo. This strategy should facilitate clarification of the role of TGF-beta in vivo in various organs where direct gene transfer seems to be difficult.

Animals↗

PubMed2000

Pituitary-adrenocortical responses to the first dyadic encounters in male rhesus monkeys: effect of dominance relationship.

Male rhesus monkeys unfamiliar with each other were paired in a cage, and blood samples were collected before and a few hours after pair formation. Adrenocorticotrophic hormone (ACTH) and cortisol levels in each blood sample were measured. Dominant-subordinate status was ascertained through two rank tests, the food competition test and the agonistic behavior test, which were performed immediately after pair formation. As a result, the dominance relationship was determined in seven pairs formed from five animals, and the differences in ACTH and cortisol values between the dominant and subordinate animal in these pairs were compared statistically. The day after the first encounter, a second encounter was conducted in randomly selected pairs of monkeys. In the first encounters, higher levels of both ACTH and cortisol were detected in dominant animals in comparison to subordinate animals. Changing the animal's partner altered the stress responses whenever the animal's dominant-subordinate status changed. The elevated levels of ACTH and cortisol in dominant animals disappeared on the day after the first encounter. In dominant animals, the pituitary-adrenocortical stress response reacts sharply to situational demands, whereas subordinate animals have a weaker response. This acute stress response is different from a chronic stress response. When the subordinate animal cannot escape, its hypothalamic-pituitary-adrenocortical axis appears to be suppressed.

Adrenocorticotropic Hormone↗