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T Maeda

Publications and source records attributed to T Maeda.

At least 325 records · Page 18Linked to original sources
PubMed1999

[A successful surgical case of billowing mitral leaflet syndrome (Barlow syndrome) combined with severe mitral regurgitation].

We report a successful surgical case of billowing mitral leaflet syndrome combined with severe mitral regurgitation. A 45-year-old man suffered from congestive heart failure and admitted our institution for precise examination. A heart murmur was pointed out by a medical examination at his high school, and mitral valve prolapse was detected by echocardiography at 23 year of age. No medication was applied because he showed no symptom. From 44 year of age, he noted palpitation on exercise. Holter monitor showed blocked PAC and Wenckebach A-V block, and transesophageal echocardiography indicated severe mitral regurgitation due to the billowing of voluminous both leaflets. At his operation, we recognized the billowing of both leaflets with torn chordae, and size of the mitral valve orifice was 8.5 x 5 cm. The huge mitral valve was replaced with a CarboMedics 31M prosthetic valve by plicating mattress stitches of native mitral annulus. Histopathologic findings showed accumulation of acid mucopolysaccharide. Postoperative echocardiography showed reduction of the left ventricular volume and preservation of the left ventricular function. Relatively slow progression of the billowing mitral leaflet syndrome did not cause apparent symptoms of heart failure in this patient. Therefore, proper selection of the procedure and timing of surgical treatments might be important for successful long-term results after operation of the billowing mitral leaflet syndrome.

Cardiac Surgical Procedures↗
PubMed1999

[Detection of serum p53 antibodies in colorectal cancer patients and the clinical significance of postoperative monitoring].

p53 protein overexpression was found to induce the production of antibodies in patient serum and, recently, the easy detection of serum antibodies has been made possible. The aim of this study is to determine the significance of serum p53 antibodies in patients with primary colorectal adenocarcinoma in comparison with their clinicopathological features, and the tumor marker sensitivities of carcinoembryonic antigen (CEA), carcinoma antigen 19-9 (CA19-9) and alpha-fetoprotein (AFP). Thirty-nine of 86 patients (45.3%) were positive for serum p53 antibodies. However, there was no relation with the cancer progression or clinicopathological findings. The sensitivities of CEA, CA19-9 and AFP were 36.0%, 38.4%, and 8.1% respectively, but there was no relation between serum p53 antibodies and these three markers. When the sensitivity of serum p53 antibodies and CEA was evaluated according to clinical stage, the presence of serum p53 antibodies was more significantly associated with stage 0, I and II colorectal cancer than was CEA. Thirty-three patients who showed preoperative positivity for serum p53 antibodies were followed by serial evaluation of circulating antibodies after resection. Negative conversions after resection were significantly higher in the "Cur A" group than in the "Cur B" or "Cur C" groups. Serum p53 antibodies appear to be a useful tumor marker independent of the other markers, especially in the early stage, and are expected to be useful in the development of a method of early diagnosis for mass screening, and as a postoperative monitoring marker for colorectal cancer.

Adult↗
PubMed1999

Influence of retinyl acetate on osteochondral junction chondrocytes in C3H and balb mice.

OBJECTIVE: To establish the pathophysiology of retinoid induced hyperostosis. METHODS: Radiographical, histological, ultrastructural, and immunohistochemical features of retinoid induced hyperostosis were evaluated using C3H-Heston mice and Balb mice. RESULTS: Dose dependent and progressive ossification was noted at extraosseous sites of both mouse strains. New bone formation was seen not only in the extraosseous tissues, but subchondral bone showed prominent proliferation. Major histopathological abnormalities appeared to take place in the chondrocytes near the osteochondral junctions, and some of the metaplastic chondrocytes near the osteochondral junction expressed osteocalcin and type I collagen, extracellular molecules normally present in bone. Species dependent responsiveness was also noted. CONCLUSION: Longterm administration of retinoids may induce an aberrant differentiation of the articular and entheseal chondrocytes near the osteochondral junctions, and the affected cells appeared to produce extracellular components including osteocalcin and type I collagen.

Animals↗
PubMed1998

Blockade of ATP-sensitive K+ channels attenuates preconditioning effect on myocardial metabolism in swine: myocardial metabolism and ATP-sensitive K+ channels.

OBJECTIVE: We investigated if blockade of ATP-sensitive K+ channels (KATP) abolishes the protective effect of ischemic preconditioning (IP) on myocardial metabolism and ischemia-induced reactive hyperemia (RH) in pigs. METHODS: IP was elicited by a single cycle of 5 min occlusion and 5 min reperfusion of coronary artery, followed by 15 min of test ischemia and 120 min of reperfusion. Vehicle or the ATP-sensitive K+ channels (KATP) blocker, glibenclamide (3 or 6 mg/kg; G3 or G6) was administered before IP (groups; IP, G3+IP, G6+IP). As respective controls, the same treatment was performed in groups without IP (groups; C, G3, G6). Tissue levels of ATP, creatine phosphate (CP) and intracellular pH (pHi) in the area at risk were measured by 31P-nuclear magnetic resonance spectroscopy. RH after 5 min of preconditioning ischemia was assessed by regional myocardial blood flow. RESULTS: ATP and pHi were preserved after 15 min of ischemia in the IP group [C/IP; ATP=57+/-4/76+/-10% of baseline, pHi=6.18+/-0.08/6.66+/-0.03, P<0.05, C vs. IP]. Both doses of glibenclamide completely abolished the ATP sparing effect of IP. The high dose completely abolished pHi preservation (G6+IP=6.33+/-0.06), while the low dose showed only a partial effect (G3+IP=6.48+/-0.03). Glibenclamide did not adversely affect myocardial metabolism in groups without IP. Glibenclamide attenuated RH after 5 min of ischemia by 30% in both subendocardium and subepicardium. CONCLUSIONS: Blockade of KATP abolished the preconditioning effect on myocardial metabolism, and partially attenuated post-ischemic reactive hyperemia in pigs. These results indicate that KATP activation might be involved in the mechanisms of these phenomena, reactive hyperemia is not sufficient to induce IP protection.

Adenosine Triphosphate↗
PubMed1998

Immunocytochemical detection of S-100beta in the periodontal Ruffini endings in the rat incisor.

Subcellular localization of S-100 protein, a kind of calcium binding proteins, was examined immunohistochemically in the Ruffini ending, a primary mechanoreceptor, in the periodontal ligament of the rat incisor. The periodontal ligament of the rat incisor was found to contain many S-100beta-immunoreactive (-IR) structures but no S-100alpha-IR elements. The S-100beta-IR structures ramified extensively to form Ruffini endings and were frequently associated with round cells, the terminal Schwann cells, which also showed S-100beta-like immunoreactivity. In many periodontal Ruffini endings, S-100beta-IR products were recognized in the cytoplasm of Schwann cells, but not in the axoplasm. However, some axon terminals which had fewer or shorter axonal fingers, were filled with S-100beta-IR products. The present findings indicated the existence of S-100beta, not S-100alpha, in axon terminals of the periodontal mechanoreceptive endings which were identified as type II Ruffini endings.

Animals↗
PubMed1998

High-resolution solution NMR structure of the minimal active domain of the human immunodeficiency virus type-2 nucleocapsid protein.

The retroviral nucleocapsid (NC) protein is a multifunctional protein essential for RNA genome packaging and viral infectivity. The NC protein, NCp8, of the human immunodeficiency virus type-II (HIV-2) is a 49 amino acid peptide containing two zinc fingers, of the type C-X2-C-X4-H-X4-C, connected by seven amino acid residues, called the "basic amino acid cluster." It has been shown that the N-terminal zinc finger flanked by the basic amino acid cluster is the minimal active domain for the specific binding to viral RNA and other functions. However, the structure-activity relationships of NCp8 have not been investigated in detail. In the present study, the three-dimensional structure of a 29 amino acid peptide, including the minimal active domain (NCp8-fl), was determined by two-dimensional 1H NMR spectroscopy with simulated annealing calculations. A total of 15 converged structures of NCp8-fl were obtained on the basis of 355 experimental constraints, including 343 distance constraints obtained from nuclear Overhauser effect connectivities, 12 torsion angle (phi, chi1) constraints, and four constraints for zinc binding. The root-mean-square deviation of the 15 converged structures was 0.29 +/- 0.04 A for the backbone atoms (N, C(alpha), C) and 1.27 +/- 0.13 A for all heavy atoms. Interestingly, the basic amino acid cluster itself was defined well, with a loop-like conformation in which three arginine residues in the cluster and one arginine residue in the zinc finger are located approximately in the same plane of the molecule and are exposed to the solvent. The structure-activity relationships are discussed on the basis of the comparison of this well-defined structure with those of other NC proteins.

Amino Acid Sequence↗
PubMed1998

Expression of caveolin-1 in human T cell leukemia cell lines.

Caveolae are plasma membrane invaginations that function as a center for signal transduction. Recent studies indicate that caveolins, the main proteins in caveolae, serve as scaffolding proteins onto which many classes of signaling molecules are assembled. There are multiple forms of caveolins: caveolin-1 and caveolin-2 are expressed as stable heterooligomeric complexes within most cell types, while caveolin-3 is restricted to striated muscle cells. However, neither caveolin proteins nor caveolae structures are detected in peripheral blood cells or blood cell lines. We identified caveolin-1 in one T cell leukemia cell line, a subline of Jurkat cells, by immunostaining and Western blotting. The cells showed enlarged cell bodies similar to activated T cells. This led us to investigate caveolin expression in adult T cell leukemia (ATL) cell lines, which are known to be constitutively activated. Two of five ATL cell lines expressed caveolin-1. The phenotype of caveolin-1-positive cells expressed not only high levels of the T cell activation markers, as with CD25 or HLA-DR, but also CD54 at extremely high levels. These findings demonstrate for the first time that hematological cells express caveolin-1 in certain states of cell activation. In addition, the caveolin-1 expression may be a useful marker for the diagnosis of ATL malignancy.

Biomarkers, Tumor↗
PubMed1998

A novel human RasGAP-like gene that maps within the prostate cancer susceptibility locus at chromosome 1q25.

We report the molecular cloning of a human cDNA that encodes a molecule having striking homology with Ras-specific GTPase-activating proteins (RasGAPs). Among previously described RasGAPs, the cDNA product is most closely related to Caenorhabditis elegans GAP-2, including a predicted coiled-coil structure near the carboxyl terminus. Expression of the cDNA in Saccharomyces cerevisiae defective in one of two RasGAPs, Ira2, complemented loss of the Ira2 function, indicating that the cDNA product functions as a RasGAP. The RasGAP-like gene is located on the human chromosome 1q25, the locus that appears to contain a hereditary prostate cancer susceptible gene, HPC1.

Amino Acid Sequence↗
PubMed1998

Regulation of Zn-alpha2-glycoprotein-mediated cell adhesion by kininogens and their derivatives.

MC3T3-E1 (mouse osteoblast-like) cells adhered to a tissue culture plate coated with human Zn-alpha2-glycoprotein (Znalpha2gp). The adhesion of MC3T3-E1 cells to Znalpha2gp was inhibited by synthetic peptides such as RGDS and ELRGDV, and by antibody against vitronectin receptor. These findings suggested that the RGD region of Znalpha2gp interacts with the vitronectin receptor (alphavbeta3) on the MC3T3-E1 cell surface. Furthermore, we found that the common heavy chain of both HMW- and LMW-kininogens accelerated the Znalpha2gp-mediated MC3T3-E1 cell adhesion. Among the three domains of the common heavy chain of both kininogens, domain 3 promoted the cell adhesion by up to 200%. Among the nine synthetic peptides covering domain 3, the peptide, N334AEVYVVPWEKKIYPTVN351 accelerated in a dose-dependent manner the Znalpha2gp- and vitronectin (VN)-mediated MC3T3-E1 cell adhesion. These findings suggested that a defined region of domain 3 is responsible for the acceleration of cell adhesion.

3T3 Cells↗
PubMed1998

Alcohol consumption enhances liver metastasis in colorectal carcinoma patients.

BACKGROUND: It is important to identify risk factors for liver metastasis in patients with colorectal carcinoma because the liver is the most common site of recurrence. Alcohol consumption reportedly is associated with hematogenous metastasis in certain animal models. Furthermore, some studies have shown that carmofur, a derivative of 5-fluorouracil, is particularly effective as adjuvant chemotherapy for colorectal carcinoma, and may even suppress liver metastasis, although the mechanism by which this occurs remains unknown. In addition, carmofur is known to inhibit alcohol metabolism. To the authors' knowledge, the relation between liver metastasis in colorectal carcinoma and alcohol consumption has not been examined previously. Therefore, the authors studied the relations between liver metastasis in colorectal carcinoma and various clinicopathologic factors including alcohol consumption status. METHODS: This study was comprised of 133 colorectal carcinoma patients with invasion beyond the submucosal layer who had undergone surgical resection. The subjects were examined and divided into two groups according to the occurrence or absence of liver metastasis. The relations between liver metastasis and other clinicopathologic factors were analyzed by univariate and multivariate statistical methods. RESULTS: Univariate analysis showed alcohol consumption (P=0.0021) and blood vessel invasion (P=0.0045) were correlated with liver metastasis. Multivariate analysis showed both to be independent risk factors for liver metastasis. CONCLUSIONS: Alcohol consumption is an independent risk factor for liver metastasis in colorectal carcinoma patients. Therefore, patients with colorectal carcinoma who drink alcohol require intensive examination and follow-up with respect to liver metastasis. Further study is necessary to confirm the effect of adjuvant chemotherapy using carmofur in colorectal carcinoma patients.

Adult↗
PubMed1998

Analogs of cyclic nucleotides in rat liver preservation.

BACKGROUND: Cyclic nucleotides mediate intracellular signal transduction of several vasodilators. In addition to its vascular relaxant effects, cAMP is known to protect endothelial cells and to suppress Kupffer cell activation. On the other hand, cGMP potently ameliorates adhesion of leukocytes and platelets. We tested the effects of two analogs of cyclic nucleotides (8bromo cyclic adenosine monophosphate [8br-cAMP] and 8bromo cyclic guanosine monophosphate [8br-cGMP]) in rat liver preservation. METHODS: In experiment 1, either analog (0.1-1.0 mM) alone was added to University of Wisconsin (UW) solution in a survival study. In experiment 2, donors and recipients were also treated with 8br-cAMP or 8br-cGMP, with the following three groups tested: group 1=control; group 2=administration of 8br-cAMP to donors, UW solution, and recipients; group 3=administration of 8br-cGMP to donors, UW solution, and recipients. Experiment 3 tested combined treatments: group 4=administration of 8br-cGMP to donors and UW solution, and cAMP to recipients; group 5=administration of 8br-cAMP to donors and UW solution, and 8br-cGMP to recipients. To elucidate the roles of each nucleotide, two further groups were tested: group 6=administration of 8br-cAMP to donors and UW solution; group 7=administration of 8br-cGMP to recipients. In experiment 4, rats in groups 1, 5, 6, and 7 were killed at several time points after reperfusion, and percent graft blood flow (%BF), number of accumulated neutrophils, plasma levels of tumor necrosis factor-alpha and interleukin-1, and serum alanine aminotransferase levels were examined. RESULTS: In experiments 1 and 2, no significant effect was observed on animal survival. In experiment 3, a significant increase in animal survival was observed only in group 5 (100%, 7/7, P=0.0004 vs. group 1: 16.7%, 2/12). In group 5, no improvement of %BF was observed during the early phase of reperfusion (15 and 30 min) compared with that in group 1. On the other hand, the %BF of group 5 was significantly higher in the later phase (6 hr), consistent with the decrease in accumulation of neutrophils observed then. Production of tumor necrosis factor-alpha and serum alanine aminotransferase levels were also reduced with this treatment. Histologically, the bleeding and segmental necrosis, observed in group 1, were completely prevented in group 5. CONCLUSIONS: We conclude that restoration of grafts with cAMP and administration of cGMP to recipients led to successful transplantation, and that the two analogs acted synergistically in opposing preservation and reperfusion injury without improvement of graft blood flow during the early phase of reperfusion. The effect was due to their regulation of neutrophil activation and sequestration.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1998

Calretinin-like immunoreactivity in the regenerating periodontal ruffini endings of the rat incisor following injury to the inferior alveolar nerve.

Regeneration of calretinin (CR)-like immunoreactive (IR) nerve fibers was investigated in the periodontal ligament of the rat lower incisor following resection of the inferior alveolar nerve (IAN). In addition, the degeneration and regeneration processes of periodontal nerve fibers were examined by immunohistochemistry for protein gene product 9.5 (PGP 9.5), a general neuronal marker. In normal animals, the periodontal nerve fibers showing PGP 9.5-like immunoreactivity (LI) formed either periodontal Ruffini endings with expanded arborization and thin free nerve endings in the alveolar half of the ligament. Thick CR-IR nerve fibers also appeared in a dendritic fashion in the same region, but thin CR-IR nerve fibers were rarely observed. Five days following resection of the IAN, a major population of PGP 9.5-IR and all CR-IR nerve fibers disappeared except for some thin PGP 9.5-IR nerves in the periodontal ligament. Regenerated PGP 9.5-IR nerve fibers appeared around 7 days following resection, in contrast to a very small number of regenerated CR-IR nerve fibers. Around 14-21 days following resection, the number and terminal morphology of regenerated PGP 9.5-IR nerve fibers were comparable to those observed in normal animals, but the number of regenerated CR-IR nerve fibers was still smaller than that of normal animals. The number of regenerated CR-IR nerve fibers increased to return to normal by 56 days following injury. The delay of expression of CR-LI in the regenerated periodontal Ruffini endings suggests that functional recovery of periodontal Ruffini endings occurred after the completion of the regeneration of periodontal nerve fibers.

Animals↗
PubMed1998

A possible role of RGS9 in phototransduction. A bridge between the cGMP-phosphodiesterase system and the guanylyl cyclase system.

In the current concept of phototransduction, the concentration of cGMP in retinal rod outer segments is controlled by the balance of two enzyme activities: cGMP phosphodiesterase (PDE) and guanylyl cyclase (GC). However, no protein directly mediates these two enzyme systems. Here we show that RGS9, which is suggested to control PDE activity through regulation of transducin GTPase activity (He, W., Cowan, C. W., and Wensel, T. G. (1998) Neuron 20, 95-102), directly interacts with GC. When proteins in the Triton X-100-insoluble fraction of bovine rod outer segments were isolated by two-dimensional gel electrophoresis and binding of GC to these proteins was examined using a GC-specific antibody, proteins (55 and 32 kDa) were found to interact with GC. However, the activity of GC bound to the 55-kDa protein was not detected. This observation was elucidated by the finding that the 55-kDa protein inhibited GC activity in a dose-dependent manner. Amino acid sequence showed that five peptides derived from the 55-kDa protein were identical to corresponding peptides of RGS9. Together with other biochemical characterization of the 55-kDa protein, these observations indicate that the 55-kDa protein is RGS9 and that RGS9 inhibits GC. RGS9 may serve as a mediator between the PDE and GC systems.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1998

Protein phosphatase 2Calpha inhibits the human stress-responsive p38 and JNK MAPK pathways.

MAPK (mitogen-activated protein kinase) cascades are common eukaryotic signaling modules that consist of a MAPK, a MAPK kinase (MAPKK) and a MAPKK kinase (MAPKKK). Because phosphorylation is essential for the activation of both MAPKKs and MAPKs, protein phosphatases are likely to be important regulators of signaling through MAPK cascades. To identify protein phosphatases that negatively regulate the stress-responsive p38 and JNK MAPK cascades, we screened human cDNA libraries for genes that down-regulated the yeast HOG1 MAPK pathway, which shares similarities with the p38 and JNK pathways, using a hyperactivating yeast mutant. In this screen, the human protein phosphatase type 2Calpha (PP2Calpha) was found to negatively regulate the HOG1 pathway in yeast. Moreover, when expressed in mammalian cells, PP2Calpha inhibited the activation of the p38 and JNK cascades induced by environmental stresses. Both in vivo and in vitro observations indicated that PP2Calpha dephosphorylated and inactivated MAPKKs (MKK6 and SEK1) and a MAPK (p38) in the stress-responsive MAPK cascades. Furthermore, a direct interaction of PP2Calpha and p38 was demonstrated by a co-immunoprecipitation assay. This interaction was observed only when cells were stimulated with stresses or when a catalytically inactive PP2Calpha mutant was used, suggesting that only the phosphorylated form of p38 interacts with PP2Calpha.

Amino Acid Sequence↗
PubMed1998

Molecular cloning of the rat Tpx-1 responsible for the interaction between spermatogenic and Sertoli cells.

We previously showed in a primary culture of rat testicular cells that spermatogenic cells specifically bind to somatic Sertoli cells and that this interaction is needed for spermatogenic cells to differentiate in vitro. Adopting an expression cloning procedure, we here isolated a cDNA coding for a spermatogenic cell protein whose expression gave a cultured cell line the ability to bind to Sertoli cells. The protein, 243 amino acids with a putative N-terminal signal peptide and a C-terminal Cys-rich region, turned out to be the rat homologue of a testicular protein called Tpx-1 whose function had yet to be determined. A polyclonal antibody raised against bacterially expressed Tpx-1 significantly inhibited the binding of spermatogenic cells to Sertoli cells. The above results indicated that Tpx-1 is a testicular cell adhesion molecule responsible for the specific interaction between spermatogenic and Sertoli cells.

Amino Acid Sequence↗
PubMed1998

Determination of very volatile organic compounds in environmental water by injection of a large amount of headspace gas into a gas chromatograph.

An injection method for a large amount of headspace gas which enables determination of trace amounts of very volatile organic compounds (VVOCs), dichlorodifluoromethane, chloromethane, vinyl chloride, bromomethane, chloroethane and trichlorofluoromethane in all kinds of environmental water was developed. A gas phase equilibrated with the water phase in a vial was purged with helium for a short time. The VVOCs were then introduced into a trapping tube packed with Tenax TA, which had been cooled using carbon dioxide. After trapping, the VVOCs were thermally desorbed and put into a GC-MS system for subsequent analysis. This method is applicable to various types of samples.

Chromatography, Gas↗
PubMed1998

Interleukin-15 (IL-15) can replace the IL-2 signal in IL-2-dependent adult T-cell leukemia (ATL) cell lines: expression of IL-15 receptor alpha on ATL cells.

Interleukin-15 receptor (IL-15R) and IL-2R have the same beta and gamma chains, but IL-15R has a specific alpha chain distinct from that of IL-2Ralpha, which is indispensable for the high affinity binding of IL-15. In the present study, we examined four IL-2-dependent adult T-cell leukemia (ATL) cell lines for their IL-15R expression. All cell lines bound IL-15, which was not inhibited by a 100-fold excess amount of IL-2, proliferated in response to IL-15 to the same degree as to the stimulation with IL-2, and were maintained without IL-2. The responses to 1L-15 were inhibited by the antibodies against IL-2R beta or gamma chains but was not by the IL-2R alpha chain antibody. [125I]-IL-15 exhibited a single high-affinity binding with an apparent kd of 0.17 nmol/L. Reverse transcription-coupled polymerase chain reaction (RT-PCR) showed that the cell lines had the mRNA of IL-15R alpha. The cell lines also had IL-15 mRNA. Despite the presence of IL-15 mRNA, the cell lines did not secrete IL-15, and the culture supernatants of fresh ATL cells and plasma from the patients did not contain a detectable amount of IL-15 with a few exceptional cases, although fresh ATL cells also responded to IL-15. These results suggest that ATL cells have the complete form of IL-15R and respond to IL-15. Such an IL-15-dependent cell proliferation mechanism might be used in the development of ATL and for the invasion and proliferation of ATL cells in the visceral organs.

Adult↗