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Biomedical subjects

Y Kitamura

Publications and source records attributed to Y Kitamura.

At least 109 records · Page 6Linked to original sources
PubMed2000

Evaluation of bioactive bone cement in canine total hip arthroplasty.

Total hip arthroplasties (THAs) were performed in beagle dogs using a bioactive bone cement (BABC) consisting of a silane-treated apatite- and wollastonite-containing glass-ceramic (AW glass-ceramic) powder and a silica glass powder as the filling particles and a bisphenol-A-glycidyl dimethacrylate-based resin (Bis-GMA-based resin) as the organic matrix. The outcomes were compared with the results of polymethylmethacrylate (PMMA) bone cement. The mechanical properties of the BABC were stronger than those of PMMA bone cement. The bonding strength of the BABC to bone in the dogs' femora increased with time and reached 3.7 MPa at 24 months after implantation whereas that of PMMA bone cement was 2.0 MPa (p < 0.05). Histological examination showed direct bonding between the BABC and the femoral bone for up to 24 months after implantation. However, with PMMA bone cement an intervening soft-tissue layer consistently was observed at the bone-cement interface. Direct bonding at the interface between the BABC and the bone through a calcium phosphorous layer 30 microm-thick was revealed by scanning electron microscopy. Femoral bone resorption was observed at 24 months after implantation in the BABC group, but it was not observed in the PMMA bone cement group. Direct bonding between BABC and the bone may have accelerated femoral bone resorption. Cement fractures of the BABC were observed on the acetabular side 24 months after implantation. Weak bonding between the BABC and an acetabular component made of ultrahigh molecular weight polyethylene (UHMWPE), relatively high elastic characteristics of BABC, and weakness of the calcium phosphorous layer formed on the surface of this cement seemed to lead to failure at 24 months on the acetabular side.

Animals↗
PubMed2000

Bioactive polymethyl methacrylate-based bone cement: comparison of glass beads, apatite- and wollastonite-containing glass-ceramic, and hydroxyapatite fillers on mechanical and biological properties.

A new bioactive bone cement (designated GBC) consisting of polymethyl methacrylate (PMMA) as an organic matrix and bioactive glass beads as an inorganic filler has been developed. The bioactive beads, consisting of MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) glass, have been newly designed, and a novel PMMA powder was selected. The purpose of the present study was to compare this new bone cement GBC's mechanical properties in vitro and its osteoconductivity in vivo with cements consisting of the same matrix as GBC and either apatite- and wollastonite-containing glass-ceramic (AW-GC) powder (designated AWC) or sintered hydroxyapatite (HA) powder (HAC). Each filler added to the cements amounted to 70 wt %. The bending strength of GBC was significantly higher than that of AWC and HAC (p < 0.0001). Cements were packed into intramedullar canals of rat tibiae in order to evaluate osteoconductivity as determined by an affinity index. Rats were sacrificed at 2, 4, and 8 weeks after operation. An affinity index, which equaled the length of bone in direct contact with the cement expressed as a percentage of the total length of the cement surface, was calculated for each cement. At each time interval studied, GBC showed a significantly higher affinity index than AWC or HAC up to 8 weeks after implantation (p < 0.03). The value for GBC increased significantly with time up to 8 weeks (p < 0.006). The handling property of GBC was comparable with that of PMMA bone cement. Our study revealed that the higher osteoconductivity of GBC was due to the higher bioactivity of the bioactive glass beads at the cement surface and the lower solubility of the new PMMA powder to MMA monomer. In addition, it was found that the smaller spherical shape and glassy phase of the glass beads gave GBC strong enough mechanical properties to be useful under weight-bearing conditions. GBC shows promise as an alternative with improved properties to the conventionally used PMMA bone cement.

Animals↗
PubMed2000

Nitric oxide generation around buccal ganglia accompanying feeding behavior in the pond snail, Lymnaea stagnalis.

Although there are many lines of evidence for both the presence of nitric oxide synthase (NOS) in the central nervous system (CNS) and the effects of NO on activating and modulating the feeding circuit in Lymnaea stagnalis, there has been no direct evidence that NO generation in the CNS accompanies feeding behavior. In the present study, we used a NO specific electrode to measure the increase in NO concentration around the buccal ganglia when the lips of semi-intact preparations of L. stagnalis were stimulated by sucrose. The NO concentration of the buccal ganglia was significantly increased by an application of sucrose to the lips. A NO scavenger and a NOS inhibitor suppressed this increase in NO concentration. A pair of putative NO-generative neurons in the buccal ganglia, the B2 cells, are active during the inter-feeding phase, and the bursting of the B2 cell elicited by sucrose application starts simultaneously with the feeding response. The rhythmic pulses of NO generation corresponded well with the rhythmic bursting of the B2 cells, which itself corresponds to the 'fictive feeding response'. The present data provide the first direct evidence that NO is generated in the buccal ganglia of L. stagnalis and is involved in a specific behavior such as feeding.

Animals↗
PubMed2000

Primary T-cell non-Hodgkin's malignant lymphoma of the appendix.

A case of primary T-cell lymphoma of the appendix in an 84-year-old female was reported. Appendectomy was performed as a result of the clinical diagnosis of acute appendicitis, due to the rebound tenderness of McBurney's point and thickness of the appendix wall as determined from ultra echo sonograph. Grossly, the surgical resected appendix did not have a dominant inflammatory appearance, therefore a tumor was suspected. Microscopic examination showed diffused proliferation of large and medium size lymphoma cells. Immunohistochemical examination further revealed that the lymphoma cells were positive for T-cell markers. To ensure this was a T-cell lymphoma, molecular examination was performed using paraffin-embedded tissue sections, since T-cell lymphoma of the appendix is extremely rare. Polymerase chain reaction (PCR) single-strand conformation polymorphism (SSCP) analysis demonstrated monoclonal T-cell receptor gene rearrangement. T-cell-rich B-cell lymphoma was excluded. To our knowledge, this is the first reported case of primary T-cell lymphoma of the appendix. PCR-SSCP analysis in paraffin-embedded tissue section was very useful in the diagnosis of lymphoma cell monoclonality.

Aged↗
PubMed2000

Inhibitory effects of antisense oligonucleotides on the expression of procollagen type III gene in mouse hepatic stellate cells transformed by simian virus 40.

The effects of phosphorothioate antisense oligonucleotides (ASO), complementary to the AUG start region, the junctional region of the intron and exon, and to exon of the procollagen type III gene, were investigated in a mouse hepatic stellate cell (HSC) line transformed by the simian virus 40 gene, SV68c-IS cells. ASO were transfected by lipofection. Immunohistochemistry, western and northern blotting showed inhibitory effects on procollagen type III gene expression by ASO that were complementary to the AUG start region and the junctional region of the intron and exon 2. However, ASO complementary to the exon 2 and 3, junctional region of the intron and exon 3, and sense oligonucleotides complementary to each ASO did not show any inhibitory effects. The effects of ASO complementary to the AUG start region were greater than those of ASO complementary to the junctional region. The effects of ASO were transient and a large amount of ASO was required to induce inhibitory effects without lipofection. ASO were effective in inhibiting the expression of the procollagen type III gene in the HSC which is well known to play a critical role in liver fibrosis.

Actins↗
PubMed2000

Quantitative detection of binding of PCNA protein to DNA strands on a 27 MHz quartz-crystal microbalance.

We report here binding kinetics of proliferating cell nuclear antigen (PCNA) to the dsDNA immobilized on a 27 MHz quartz-crystal microbalance. PCNA is a toroidal-shaped protein and encircles dsDNA sliding along the strand. The binding behavior of this sliding clamp protein was compared with those of other side binding proteins such as GCN4-bZIP and Zn-finger peptides.

Base Sequence↗
PubMed2000

Immunohistochemical studies on vascular endothelial growth factor and platelet endothelial cell adhesion molecule-1/CD-31 in islet transplantation.

Neovascularization may be necessary for better and longer function of transplanted islets. Vascular endothelial growth factor (VEGF) is known to be one of the most important factors of angiogenesis. Recently, VEGF was reported to be expressed in islets of normal pancreas. We studied the expression of VEGF and neovascularization related peptides in transplanted islets. To determine the angiogenic microcapillary, immunochemical staining was performed for Factor VIII-related antigen (von Willebrand factor [vWF]) and platelet endothelial cell adhesion molecule-1/CD31 (PECAM-1), both of which are known as markers of the angiogenic microvessel. Transplantable islets were isolated from Lewis rats (8-10 weeks of age) by discontinuous dextran gradient after collagenase digestion. Seven to twelve hundred islets were injected into the portal vein (IPV group, n = 7) or transplanted into subnephrocapsular cavity (SNC, n = 12) of the same descent rats. In the IPV group, the liver was resected 1 hour, 1 week, or 4 weeks after transplantation (Tx). In the SNC group, the kidney was resected 1, 3, 7, or 28 days after Tx. Each tissue was fixed in formaldehyde and embedded in paraffin. Serial 4-microm slices were immunostained for insulin, VEGF, PECAM-1, or vWF using specific antibodies. In IPV group, insulin-positive cells were VEGF positive as were in the normal pancreas at all time points. Islets of 1 hour after Tx were barely PECAM-1 positive as were in normal pancreas, but islets became weakly stained at 7 and 28 days after Tx. In vWF staining, transplanted islets showed stronger staining than those in the normal pancreas. In SNC group, VEGF was also stained in insulin-positive cells at 1, 3, 7, and 28 days. In PECAM-1 staining, islets of 1 day after Tx were barely stained as were in normal pancreas. However, the staining was increasingly enhanced from 3 to 7 days and then appeared weakened at 28 days after Tx. In vWF staining, islets were always vWF positive, as was seen in IPV group. This study revealed that PECAM-1 appeared in islets after islet Tx, suggesting that neovascularization occurs within the islet grafts. On the other hand, VEGF of transplanted islet did not obviously vary with time. Enhancement of the neovascularization may lead to better results of islet Tx.

Animals↗
PubMed2000

Annexin VII as a novel marker for invasive phenotype of malignant melanoma.

Both F10 and BL6 sublines of B16 mouse melanoma cells are metastatic after intravenous injection, but only BL6 cells are metastatic after subcutaneous injection. While examining the genetic difference between the two sublines, we found a marked reduction of annexin VII expression in BL6 cells. In addition, fusion cell clones of both sublines were as poorly metastatic as F10 cells after subcutaneous injection, and contained the annexin VII message as abundantly as F10 cells. Hence, we examined whether the annexin VII expression was correlated with the less malignant phenotype of clinical cases by immunohistochemistry. Immunoreactivities to anti-annexin VII antibody in melanoma cells were evaluated quantitatively by using skin mast cells as an internal positive control. Eighteen patients with malignant melanoma were divided into two groups: lymph node metastasis-negative and positive groups. The ratio of numbers of patients positive versus negative to the antibody was significantly larger in the former than in the latter group. These results not only indicated that annexin VII serves as a marker for less invasive phenotype of malignant melanoma, but also suggested a possible role of annexin VII in tumor suppression.

Adolescent↗
PubMed2000

Integrated hepatitis B virus DNA preserves the binding sequence of transcription factor Yin and Yang 1 at the virus-cell junction.

Accumulated findings have indicated that hepatitis B virus (HBV) DNA integrates into the cellular DNA of HBV-infected chronic hepatitis tissues. The integrated sequence (IS) of HBV DNA at the virus-cell junction is conserved in a 25-bp region which is adjacent to direct repeat 1. A cellular protein which we purified from the nuclear extract of HepG2 cells binds to the IS and was designated IS binding protein 3 (ISBP3). The amino acid sequence of ISBP3 was determined and found to be identical to that of transcription initiation factor Yin and Yang 1 (YY1). An antibody against C-terminal amino acids of YY1 recognized ISBP3 in a Western blot analysis and an electrophoretic mobility shift assay. Furthermore, ISBP3 also interacted with Y3, which corresponds to the YY1 binding sequence, to enhance intramolecular recombination of polyomavirus DNA. Although YY1 is known as a transcription factor, the IS did not exhibit any effect on the transcription of precore and pregenome RNAs. The possible involvement of YY1 in the intramolecular recombination of linear replicative HBV DNA has been examined (Y. Hayashi et al., unpublished data). Data suggest that YY1 is involved in the joining reaction between HBV DNA and cellular DNA to form the virus-cell junction.

Amino Acid Sequence↗
PubMed2000

The binding site of transcription factor YY1 is required for intramolecular recombination between terminally repeated sequences of linear replicative hepatitis B virus DNA.

In the replication cycle of hepadnavirus DNA, the double-stranded linear form of viral DNA is generated as a minor replicative intermediate, which is efficiently converted to covalently closed circular DNA (cccDNA) by intramolecular recombination (W. Yang and J. Summers, J. Virol. 69:4029-4036, 1995). We previously found a binding site of transcription factor Yin and Yang 1 (YY1) in one terminal region of the double-stranded linear replicative hepatitis B virus (HBV) DNA (M. Nakanishi-Matsui, Y. Hayashi, Y. Kitamura, and K. Koike, J. Virol. 74:5562-5568, 2000). However, it is not known whether the YY1-binding site is required for the intramolecular recombination of HBV DNA. In this study, we established an HBV-producing system in which the cccDNA appeared to be generated from the transfected linear DNA or the linear replicative DNA by nonhomologous end joining (NHEJ) or by both NHEJ and homologous recombination between terminally repeated sequences, respectively. When the YY1-binding site in the terminal region of transfected linear viral DNA was mutated, the cccDNA was generated merely by NHEJ. Results suggest that the YY1-binding site in the terminal region of linear replicative HBV DNA is required for intramolecular recombination between terminally repeated sequences.

Base Sequence↗
PubMed2000

Upregulation of two death pathways of perforin/granzyme and FasL/Fas in septic acute respiratory distress syndrome.

Accumulation and activation of inflammatory cells in the lung characterize the acute respiratory distress syndrome (ARDS). However, the precise mechanism for lung epithelial and endothelial cell damage remains unknown. Based on evidence that rapid apoptosis caused by CD8(+) cytolytic T cells can induce pathological cell death, we hypothesized that this mechanism may also participate in the acute lung injury, and attempted to evaluate apoptosis-related factors in bronchoalveolar lavage fluid (BALF) from ARDS patients. Quantitative polymerase chain reaction (PCR) analysis revealed that the messenger ribonucleic acids (mRNAs) for several apoptosis molecules, such as perforin, granzyme A, granzyme B, FasL, and Fas were highly upregulated in the acute phase of ARDS following sepsis. In contrast, low or negligible mRNA expression of these molecules was detected in patients with normal lung function, in septic patients without lung injury (septic non-ARDS), and in patients in the late phase of septic ARDS (late ARDS). While the genes of the classic proinflammatory cytokines interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), IL-6, and IL-8, and inducible nitric oxide synthase (iNOS) were upregulated in septic non-ARDS or late ARDS patients, expressions of these genes in the acute phase of septic ARDS were most distinct. The immunofluorescence flow cytometry showed that only the lymphocyte population in BALF from acute phase of septic ARDS patients expressed perforin and granzyme. The level of soluble FasL in the BALF increased only in the acute ARDS patients. These results thus suggested that the dual apoptosis pathway, perforin/granzyme and FasL/Fas system, is likely to be another participant for the pathogenesis of acute lung injury.

Adult↗
PubMed2000

A role for heterologous gap junctions between melanoma and endothelial cells in metastasis.

F10 and BL6 sublines of B16 mouse melanoma cells are metastatic after intravenous injection, but only BL6 cells are metastatic after subcutaneous injection. We found that connexin (Cx) 26 is upregulated in BL6 cells. To examine gap junction formation, we devised a coculture system, in which an opened vein segment was placed at the bottom of a culture dish and then dye-labeled melanoma cells were seeded onto it. Immunohistochemistry indicated that the vein segment preserved the integrity of the endothelial monolayer. In this system, BL6 cells could transfer dye into endothelial cells but F10 cells could not. Transfection with wild-type Cx26 rendered F10 cells competent for coupling with endothelial cells and as spontaneously metastatic as BL6 cells. Conversely, transfection with a dominant-negative form of Cx26 rendered BL6 cells deficient in coupling and less metastatic. In human melanoma lesions, the level of Cx26 expression was low in melanoma cells residing in the basal layer, but significantly upregulated in melanoma cells invading the dermis. The results suggested that Cx26 plays a role in intravasation and extravasation of tumor cells through heterologous gap junction formation with endothelial cells.

Animals↗
PubMed2000

The parkinsonian models: invertebrates to mammals.

In contrast to Alzheimer's disease, effective therapeutic options are available for Parkinson's disease. Therapy of dopamine replacement such as levodopa improves the symptoms of this disease, but does not inhibit neurodegeneration in the substantia nigra. Numerous studies have suggested that endogenous and environmental neurotoxins, and oxidative stress may participate in this disease, but the detailed mechanisms are still unclear. Recent genetic studies in familial Parkinson's disease and parkinsonism show several gene mutations. This new information regarding pathogenesis offers novel prospects for therapy. To develop novel neuroprotective drugs, it is necessary to have a model for each type of parkinsonism. This review summarizes current findings regarding parkinsonian models in vertebrates and invertebrates and discusses their value.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2000

Mechanisms of [2,3-butanedione bis(N4-dimethylthiosemicarbazone)]zinc (Zn-ATSM2)-induced protection of cultured hippocampal neurons against N-methyl-D-aspartate receptor-mediated glutamate cytotoxicity.

Hyperexcitation of glutamatergic neurons may play a key role in ischemia-related neurodegeneration. Recent studies have suggested that the zinc ion (Zn2+), which is present in the central nervous system, has a modulatory role in glutamatergic neuron activity. Zinc ions block glutamate-induced depolarizing currents and neuronal damage by binding with zinc sites on the NMDA subtypes. Therefore, we examined the usefulness of zinc as a therapeutic agent for the prevention of ischemic neuronal damage in the brain. In our previous study, 2,3-butanedione bis(N4-dimethylthiosemicarbazonato) zinc complex (Zn-ATSM2), with high brain uptake, showed significant neuroprotective effects against cerebral ischemia in rats when administered systemically. In this study, to elucidate the mechanism of the neuroprotective effect of Zn-ATSM2, we first examined its in vitro protective effects against glutamate-, NMDA- and kainite-induced neurotoxicity in primary cultures of hippocampal neurons. Zn-ATSM2 elicited protective effects against this glutamate- and NMDA-induced neurotoxicity, but did not affect kainite-induced cytotoxicity. In addition, we studied the effects of Zn-ATSM2 on influx of Ca2+, which undergoes modification subsequent to NMDA activation. Zn-ATSM2 significantly decreased glutamate-induced 45Ca2+ uptake. Thus, Zn-ATSM2 protected against glutamate-induced neurotoxicity and its protective effect was, at least in part, due to the blockage of NMDA receptor-mediated Ca2+ influx.

Animals↗
PubMed2000

Multiseptate gallbladder with cholelithiasis diagnosed incidentially in an elderly patient.

A 70-year-old woman with rheumatoid arthritis was admitted to our hospital because of gastric ulcers. Abdominal echography incidentally revealed that the patient's gallbladder was multiseptate, an extremely rare anomaly. The diagnosis was confirmed by endoscopic retrograde cholangiography. This is the 26th case of multiseptate gallbladder in the world literature, but the patient is the oldest yet recorded with this condition. Furthermore, unlike most patients with multiseptate gallbladder, she had no biliary symptoms with concomitant cholelithiasis.

Aged↗