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Biomedical subjects

K Hattori

Publications and source records attributed to K Hattori.

At least 19 recordsLinked to original sources
PubMed2000

Structure and function of a novel coliphage-associated sialidase.

A coliphage named 63D, isolated previously, associated sialidase as a component of phage particles. In order to localize the enzyme in phage particles, phages were partially destroyed by sonication, and the disrupted particles were size fractionated using a sucrose density gradient. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, enzyme assay and electron micrography of the fractions revealed the enzyme to be composed of four identical subunits with a molecular mass of 90 kDa, and the subunits were cross-linked by disulfide bonds. Electron micrographic observation indicated that six enzyme molecules were localized in a phage tail plate as a hexagonal array.

Cell Fractionation↗
PubMed2000

Significance of plasma thymosin alpha1 measurements in gastric cancer patients.

Thymosin alpha1 is a cleavage product of prothymosin alpha. Expression of prothymosin alpha increases during cell proliferation. Thymosin alpha1, measurable in plasma, may be an indicator of cell proliferation especially if a cancer is present. In this report we investigated the relation between the clinical behavior of gastric cancer and the plasma thymosin alpha1 level. Plasma thymosin alpha1 was measured in 52 gastric cancer patients using a newly developed radioimmunoassay. Twenty-one tumors and lymph nodes were examined for thymosin alpha1 using immunohistochemistry. The plasma thymosin alpha1 level was higher in gastric cancer patients than in normal volunteers; and it was higher in patients with lymph node involvement than in those with negative nodes. Immunohistochemical study of thymosin alpha1 showed positivity in 52% of gastric cancers and 100% of lymph node metastasis. We concluded that a high level of plasma thymosin alpha1 suggests aggressive behavior of a gastric cancer, such as lymph node involvement.

Biomarkers, Tumor↗
PubMed2000

Bioabsorbable thread for tight tying of bones.

The purpose of this research was to develop a bioabsorbable thread for tight fixation of fractured bones and to examine its mechanical performance in an in-vitro simulation study. The thread is a blend of bioabsorbable poly(L-lactic acid); (PLLA) and poly(epsilon-caprolactone); (PCL) fibers and can be tightly connected by fusion welding of the PCL fibers. The tying strength of the PLLA-PCL blend thread was 39.7 N, which was comparable to that of stainless steel wire. A testing machine was fabricated to measure the fatigue strength of the tying by simulating bone fixation. The results showed that metal wires always failed because of breakage within 25,000 loading cycles, whereas the blend threads did not fail until 50,000 loading cycles. The looseness of tying for simulated bone fixation by the blend thread was within 1mm even after 50 000 loading cycles. In-vivo testing using rats revealed that the blend thread did not cause any severe inflammatory reaction.

Animals↗
PubMed2000

Relationships between structure and molting hormonal activity of tebufenozide, methoxyfenozide, and their analogs in cultured integument system of Chilo suppressalis Walker.

The molting hormonal activity of methoxyfenozide (RH-2485), tebufenozide (RH-5992), five analogs with various alkyl groups, and 18 acyl analogs was measured by using cultured integument of rice stem borers, Chilo suppressalis Walker. The hormonal activity of methoxyfenozide was remarkably high (EC(50) = 1.1 x 10(-9) M), being equivalent to that of tebufenozide (RH-5992). The hormonal activity of several tebufenozide analogs with varying alkyl groups such as CH(3), n-C(3)H(7), i-C(3)H(7), n-C(4)H(9) and n-C(5)H(11) at the para-position of the benzene ring furthest from the tert-butyl group was lower than that of tebufenozide (alkyl group is C(2)H(5)). The activity decreased to varying degrees as a result of replacement of the 3,5-dimethylphenyl moiety of tebufenozide with either a phenyl, naphthyl, or cyclohexyl group. Both 1- and 2-naphthyl derivatives were very active (EC(50) = 4.3 x 10(-8) M and 3.2 x 10(-8) M, respectively) without any significant difference between them. The activity of the 1-cyclohexenyl analog (EC(50) = 1.0 x 10(-7) M) was about 40x that of the corresponding 3-cyclohexenyl analog (EC(50) = 4.4 x 10(-6) M), but 1/100 that of tebufenozide. The activity varied parabolically with respect to the molecular hydrophobicity, and decreased with longer acyl moieties.

Animals↗
PubMed2000

Effect of adaptive plasticity of linear vestibulo-ocular reflex upon angular vestibulo-ocular reflex.

OBJECTIVE: The vestibulo-ocular reflex (VOR) produces compensatory eye movements during head movements. The VOR consists of the angular VOR and the linear VOR. The VOR is under adaptive control that corrects VOR performance when visual-vestibular mismatch arises during head movements. Most experiments concerning plasticity of the VOR have used the angular VOR. So far, there has been no investigation on the effect of adaptive plasticity of the linear VOR on the angular VOR. In this study, using a linear sled, we tested the hypothesis that the angular VOR is altered by changes in the linear VOR. METHODS: To modify the linear VOR, we used an adaptation paradigm. Eight subjects were translated sinusoidally at 0.125 Hz and 0.16 g peak acceleration along their inter-aural axis for 40 min, while viewing earth-fixed vertical stripes on the wall while wearing the binocular magnifying lenses. Six of the eight subjects showed an increase in linear VOR sensitivity after adaptation. Each of the six subjects who showed an increase in linear VOR sensitivity after adaptation also showed an increased angular VOR gain at 0.125 Hz. CONCLUSION: These results suggest that the linear VOR and the angular VOR share common neural pathways in such a way that a change in the synaptic efficacy of one pathway is accompanied by a commensurate change in the other.

Adaptation, Physiological↗
PubMed2000

Characterization of XET-related genes of rice.

To elucidate the mechanism of internodal elongation in rice (Oryza sativa L.), we analyzed genes encoding xyloglucan endotransglycosylase (XET), a cell wall-loosening enzyme essential for cell elongation. Four rice XET-related (XTR) genes, OsXTR1, OsXTR2, OsXTR3, and OsXTR4, were isolated and their expression patterns in rice plants determined. The expression of the four XTR genes showed different patterns of organ specificity and responses to several plant hormones. OsXTR1 and OsXTR3 were up-regulated by gibberellin and brassinosteroids, whereas OsXTR2 and OsXTR4 showed no clear response to these hormones. Expression of the four XTR genes was also investigated in elongating internodes at different developmental stages. OsXTR1 and OsXTR3 were preferentially expressed in the elongating zone of internodes, while OsXTR2 and OsXTR4 were expressed in nodes and in the divisional and elongating zones of internodes. In three genetic mutants with abnormal heights, the expression of OsXTR1 and OsXTR3 correlated with the height of the mutants, whereas no such correlation was observed for OsXTR2 and OsXTR4. Based on these observations, we discuss the roles that OsXTR1 and OsXTR3 may play in internodal elongation in rice.

Amino Acid Sequence↗
PubMed2000

[A case of left ventricular rupture and left ventricular-right atrial communication after mitral valve re-replacement].

We report a case of left ventricular rupture and left ventricular-right atrial communication after mitral valve re-replacement. A 53-year-old man was admitted to our hospital for a primary tissue failure of mitral xenograft. On June 4, 1997, he underwent mitral valve re-replacement. At 12 post operative day, he was suffered from unexpected dyspnea. The transesophageal echocardiography showed floated mitral valve and left ventricular-right atrial communication. The emergent operation was done. At the operation, posterior mitral annulus was disrupted and the disruption reached to a membranous septum. A communication was directly closed, mitral annulus was repaired with perigard and one size smaller mitral valve was implanted. The patient was discharged and returned to social life.

Fistula↗
PubMed2000

[New combination chemotherapy in urological cancers].

Although several effective therapeutic modalities are currently available for each urological cancer, there are still many patients for whom cure is not possible. Interleukin-2 (IL-2) and interferon-alpha (IFN-alpha) are both standard agents for patients with metastatic renal cell carcinoma (RCC). However, only up to 20% of patients can attain a complete response with these agents. It has been reported that for bladder transitional cell carcinoma (TCC), a cisplatin-based chemotherapy such as M-VAC chemotherapy can give patients a prognostic benefit in an adjuvant setting. There has been no therapy to improve upon M-VAC for more than a decade. In this review, several trials with new combination chemotherapies that were developed to overcome the limitations of the current therapy are discussed. These include the combination of IL-2, IFN-alpha and 5-fluorouracil for RCC, paclitaxel/gemcitabine and cisplatin/carboplatin for TCC, and paclitaxel/docetaxel and estramustine for hormone-refractory prostate cancer. The results of initial trials with these new combination therapies are promising. Large scale clinical trials, however, have yet to be done.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2000

[Successful aortic root replacement for prosthetic valve endocarditis using the freestyle stentless bioprosthesis: report of two cases].

We report two cases of prosthetic valve endocarditis which were successfully treated with aortic root replacement using the freestyle stentless bioprosthesis. Prosthetic valve endocarditis occurred in two patients after aortic valve replacement and modified Bentall operation, respectively. The aortic annulus was severely damaged and left ventriculo-aortic discontinuity was found in both cases. We used the freestyle stentless bioprosthesis, which fits well to the destroyed aortic annulus with left ventriculo-aortic discontinuity, because of its flexibility. Postoperative echocardiography revealed excellent hemodynamic results in both cases. Although the long-term results obtained with the freestyle stentless bioprosthesis, such as resistance to bacterial infection, have not been reported, this prosthesis appears to be very useful for treatment of prosthetic valve endocarditis. We expect that this prosthesis might be a option for PVE as an alternative to a homograft.

Adult↗
PubMed1999

Structure and expression of the gene encoding mouse F-box protein, Fwd2.

A novel class of ubiquitin ligases, termed the SCF complex, consists of invariable components, Skp1 and Cullin, and variable components called F-box proteins, which have a primary role in determining substrate specificity. We have isolated a cDNA encoding the mouse F-box protein Fwd2 (also known as MD6) as a possible constituent of an SCF-type ubiquitin ligase. Fwd2 cDNA contains 1890 bp with a 1362-bp open reading frame and encodes an approximately 51.5-kDa protein. Fwd2 is expressed predominantly in liver and, to a lesser extent, in the testis, lung, heart, and skeletal muscle. Immunofluorescence staining for Fwd2 protein shows a pattern with the cytoplasm. A coimmunoprecipitation assay has revealed the in vivo interaction between Skp1 and Fwd2 through the F-box domain. Fwd2 also interacts with Cul1 through Skp1, suggesting that Skp1, Cul1, and the F-box protein Fwd2 form an SCF complex (SCF(Fwd2)). We have also isolated and determined the nucleotide sequence and genomic organization of the gene that encodes mouse Fwd2. This gene spans approximately 17 kb and consists of six exons and five introns. Our results suggest that Fwd2 is an F-box protein that constitutes an SCF ubiquitin ligase complex and that it plays a critical role in the ubiquitin-dependent degradation of proteins expressed in the liver.

Amino Acid Sequence↗
PubMed1999

Molecular dissection of the interactions among IkappaBalpha, FWD1, and Skp1 required for ubiquitin-mediated proteolysis of IkappaBalpha.

The SCF complex containing Skp1, Cul1, and the F-box protein FWD1 (the mouse homologue of Drosophila Slimb and Xenopus beta-TrCP) functions as the ubiquitin ligase for IkappaBalpha. FWD1 associates with Skp1 through the F-box domain and also recognizes the conserved DSGXXS motif of IkappaBalpha. The structural requirements for the interactions of FWD1 with IkappaBalpha and with Skp1 have now been investigated further. The D31A mutation (but not the G33A mutation) in the DSGXXS motif of IkappaBalpha abolished the binding of IkappaBalpha to FWD1 and its subsequent ubiquitination without affecting the phosphorylation of IkappaBalpha. The IkappaBalpha mutant D31E still exhibited binding to FWD1 and underwent ubiquitination. These results suggest that, in addition to site-specific phosphorylation at Ser(32) and Ser(36), an acidic amino acid at position 31 is required for FWD1-mediated ubiquitination of IkappaBalpha. Deletion analysis of Skp1 revealed that residues 61-143 of this protein are required for binding to FWD1. On the other hand, the highly conserved residues Pro(149), Ile(160), and Leu(164) in the F-box domain of FWD1 were dispensable for binding to Skp1. Together, these data delineate the structural requirements for the interactions among IkappaBalpha, FWD1, and Skp1 that underlie substrate recognition by the SCF ubiquitin ligase complex.

Amino Acid Sequence↗
PubMed1999

Common pathway for the ubiquitination of IkappaBalpha, IkappaBbeta, and IkappaBepsilon mediated by the F-box protein FWD1.

FWD1 (the mouse homolog of Drosophila Slimb and Xenopus betaTrCP, a member of the F-box- and WD40 repeat-containing family of proteins, and a component of the SCF ubiquitin ligase complex) was recently shown to interact with IkappaBalpha and thereby to promote its ubiquitination and degradation. This protein has now been shown also to bind to IkappaBbeta and IkappaBepsilon as well as to induce their ubiquitination and proteolysis. FWD1 was shown to recognize the conserved DSGPsiXS motif (where Psi represents the hydrophobic residue) present in the NH(2)-terminal regions of these three IkappaB proteins only when the component serine residues are phosphorylated. However, in contrast to IkappaBalpha and IkappaBbeta, the recognition site in IkappaBepsilon for FWD1 is not restricted to the DSGPsiXS motif; FWD1 also interacts with other sites in the NH(2)-terminal region of IkappaBepsilon. Substitution of the critical serine residues in the NH(2)-terminal regions of IkappaBalpha, IkappaBbeta, and IkappaBepsilon with alanines also markedly reduced the extent of FWD1-mediated ubiquitination of these proteins and increased their stability. These data indicate that the three IkappaB proteins, despite their substantial structural and functional differences, all undergo ubiquitination mediated by the SCF(FWD1) complex. FWD1 may thus play an important role in NF-kappaB signal transduction through regulation of the stability of multiple IkappaB proteins.

Amino Acid Sequence↗
PubMed1999

A TSH/dibutyryl cAMP activated Cl-/I- channel in FRTL-5 cells.

An iodide (I) and chloride (Cl) channel has been identified in the continuously cultured FRTL-5 thyroid cell line using a cell attached patch clamp technique. The channel is activated by TSH and dibutyryladenosine cyclic monophosphate (Bt2-cAMP) but not by phorbol 12-myristate 13-acetate (TPA). Gluconate can not replace chloride or iodide and the channel is impermeable to Na+,K+ and tetraethylammonium ions. The current-voltage relationship demonstrates that the single channel current is a linear function of the clamp voltage. Single channel currents reversed at a pipette potential close to 0 mV. The mean single channel conductance was 60 pS for Cl- and 50 pS for I-. From the I-V relationship there was a strong outward rectification with Cl-, and a complete block with I-, in the single channel current above +40 mV. The feature of the channel is manifested in the single channel records by four distinct, equally spaced conductance levels. We suggest the channel is important for the transport of I and Cl ions across the apical membrane into the colloid space and is important for hormone synthesis and follicle formation.

Animals↗
PubMed1999

Expression of galectin-3 in fine-needle aspirates as a diagnostic marker differentiating benign from malignant thyroid neoplasms.

BACKGROUND: Galectin-3 is a beta-galactoside-binding protein that has been reported to be expressed preferentially in thyroid malignancies. The current study was designed to substantiate this finding further and to establish a presurgical diagnostic modality of differentiating between benign and malignant thyroid neoplasms by analyzing galectin-3 expression in fine-needle aspirates. METHODS: The expression of galectin-3 was examined immunohistochemically in total of 172 specimens: 45 primary and 20 metastatic papillary carcinomas, 8 primary and 2 metastatic follicular carcinomas, 5 primary and 3 metastatic anaplastic carcinomas, 3 primary medullary carcinomas, 25 follicular adenomas, 3 goiters, and 58 adjacent normal thyroid tissue. Alternatively, epithelial cells were isolated from the fine- needle aspirates of 14 thyroid nodules and subjected to immunoblotting analysis of galectin-3. RESULTS: Immunohistochemical analysis revealed that all thyroid malignancies of follicular cell origin (including papillary, follicular, and anaplastic carcinomas) showed high and diffuse expression of galectin-3, whereas one of the three medullary carcinomas of parafollicular cell origin displayed weaker and focal expression of galectin-3. In contrast, neither benign thyroid adenomas, goiters, nor normal thyroid tissues expressed galectin-3. Immunoblot analysis of the isolated epithelial cells detected galectin-3 in nine thyroid nodules that were proven histologically to be malignant ( eight papillary carcinomas and one follicular carcinoma) after surgical intervention, whereas galectin-3 was not detected in five nodules proven to be benign follicular adenomas. CONCLUSIONS: Galectin-3 serves as a marker of thyroid malignancy of follicular cell origin. Analysis of galectin-3 expression in fine-needle aspirates enhances the differential diagnostic accuracy between benign and malignant thyroid neoplasms.

Antigens, Differentiation↗
PubMed1999

An F-box protein, FWD1, mediates ubiquitin-dependent proteolysis of beta-catenin.

beta-catenin plays an essential role in the Wingless/Wnt signaling cascade and is a component of the cadherin cell adhesion complex. Deregulation of beta-catenin accumulation as a result of mutations in adenomatous polyposis coli (APC) tumor suppressor protein is believed to initiate colorectal neoplasia. beta-catenin levels are regulated by the ubiquitin-dependent proteolysis system and beta-catenin ubiquitination is preceded by phosphorylation of its N-terminal region by the glycogen synthase kinase-3beta (GSK-3beta)/Axin kinase complex. Here we show that FWD1 (the mouse homologue of Slimb/betaTrCP), an F-box/WD40-repeat protein, specifically formed a multi-molecular complex with beta-catenin, Axin, GSK-3beta and APC. Mutations at the signal-induced phosphorylation site of beta-catenin inhibited its association with FWD1. FWD1 facilitated ubiquitination and promoted degradation of beta-catenin, resulting in reduced cytoplasmic beta-catenin levels. In contrast, a dominant-negative mutant form of FWD1 inhibited the ubiquitination process and stabilized beta-catenin. These results suggest that the Skp1/Cullin/F-box protein FWD1 (SCFFWD1)-ubiquitin ligase complex is involved in beta-catenin ubiquitination and that FWD1 serves as an intracellular receptor for phosphorylated beta-catenin. FWD1 also links the phosphorylation machinery to the ubiquitin-proteasome pathway to ensure prompt and efficient proteolysis of beta-catenin in response to external signals. SCFFWD1 may be critical for tumor development and suppression through regulation of beta-catenin protein stability.

Adenomatous Polyposis Coli Protein↗
PubMed1999

Ubiquitin-dependent degradation of IkappaBalpha is mediated by a ubiquitin ligase Skp1/Cul 1/F-box protein FWD1.

Activation of the transcription factor nuclear factor kappa B (NF-kappaB) is controlled by proteolysis of its inhibitory subunit (IkappaB) via the ubiquitin-proteasome pathway. Signal-induced phosphorylation of IkappaBalpha by a large multisubunit complex containing IkappaB kinases is a prerequisite for ubiquitination. Here, we show that FWD1 (a mouse homologue of Slimb/betaTrCP), a member of the F-box/WD40-repeat proteins, is associated specifically with IkappaBalpha only when IkappaBalpha is phosphorylated. The introduction of FWD1 into cells significantly promotes ubiquitination and degradation of IkappaBalpha in concert with IkappaB kinases, resulting in nuclear translocation of NF-kappaB. In addition, FWD1 strikingly evoked the ubiquitination of IkappaBalpha in the in vitro system. In contrast, a dominant-negative form of FWD1 inhibits the ubiquitination, leading to stabilization of IkappaBalpha. These results suggest that the substrate-specific degradation of IkappaBalpha is mediated by a Skp1/Cull 1/F-box protein (SCF) FWD1 ubiquitin-ligase complex and that FWD1 serves as an intracellular receptor for phosphorylated IkappaBalpha. Skp1/Cullin/F-box protein FWD1 might play a critical role in transcriptional regulation of NF-kappaB through control of IkappaB protein stability.

Amino Acid Sequence↗
PubMed1999

Mesenteric venous thrombosis associated with protein C deficiency.

An 83-year-old man had gradually worsening abdominal pain and vomiting. Laparotomy revealed segmental intestinal infarction resulting from thrombosis in the superior mesenteric vein. Necrosed intestine was resected and anastomosis was performed successfully. The patient was anticoagulated with intravenous heparin and nafamostat mesilate followed by oral aspirin. He recovered rapidly. Blood chemistry revealed protein C deficiency, while protein S and antithrombin III levels were normal. Laboratory evaluation of these proteins may help define the cause of mesenteric venous thrombosis.

Abdominal Pain↗