Biomedical subjects

A Yamauchi

Publications and source records attributed to A Yamauchi.

At least 19 recordsLinked to original sources

PubMed2000

Fractalkine-mediated endothelial cell injury by NK cells.

Endothelial cells (ECs) are primary targets of immunological attack, and their injury can lead to vasculopathy and organ dysfunction in vascular leak syndrome and in rejection of allografts or xenografts. A newly identified CX3C-chemokine, fractalkine, expressed on activated ECs plays an important role in leukocyte adhesion and migration. In this study we examined the functional roles of fractalkine on NK cell activity and NK cell-mediated endothelial cell injury. Freshly separated NK cells expressed the fractalkine receptor (CX3CR1) determined by FACS analysis and efficiently adhered to immobilized full-length fractalkine, but not to the truncated forms of the chemokine domain or mucin domain, suggesting that fractalkine functions as an adhesion molecule on the interaction between NK cells and ECs. Soluble fractalkine enhanced NK cell cytolytic activity against K562 target cells in a dose- and time-dependent manner. This enhancement correlated well with increased granular exocytosis from NK cells, which was completely inhibited by the G protein inhibitor, pertussis toxin. Transfection of fractalkine cDNA into ECV304 cells or HUVECs resulted in increased adhesion of NK cells and susceptibility to NK cell-mediated cytolysis compared with control transfection. Moreover, both enhanced adhesion and susceptibility of fractalkine-transfected cells were markedly suppressed by soluble fractalkine or anti-CX3CR1 Ab. Our results suggest that fractalkine plays an important role not only in the binding of NK cells to endothelial cells, but also in NK cell-mediated endothelium damage, which may result in vascular injury.

Adjuvants, Immunologic↗

PubMed2000

Eosinophil-specific regulation of gp91(phox) gene expression by transcription factors GATA-1 and GATA-2.

The glycoprotein gp91(phox) is an essential component of the phagocyte NADPH oxidase and is expressed in eosinophils, neutrophils, monocytes, and B-lymphocytes. We previously suggested an eosinophil-specific mechanism of gp91(phox) gene expression. To elucidate the mechanism, we performed functional assays on deletion mutants of the gp91(phox) promoter in various types of gp91(phox)-expressing cells. A 10-base pair (bp) region from bp -105 to -96 of the promoter activated transcription of the gene in eosinophilic cells, but not in neutrophilic, monocytic, or B-lymphocytic cells. A 2-bp mutation introduced into the GATA site spanning bp -101 to -96 (-98GATA site) of the fragment abolished its activity. Gel shift assays using a GATA competitor and specific antibodies demonstrated that both GATA-1 and GATA-2 specifically bound to the -98GATA site with similar affinities. Individual transfection of GATA-1 and GATA-2 into Jurkat cells, which have neither endogenous GATA-1 nor GATA-2, activated the -105/+12 construct in a -98GATA site-dependent manner. Combined transfection of GATA-1 and GATA-2 activated the promoter less than transfection of GATA-1 alone. These results suggest that GATA-1 is an activator and that GATA-2 is a relative competitive inhibitor of GATA-1 in the expression of the gp91(phox) gene in human eosinophils.

Base Sequence↗

PubMed2000

150-kDa oxygen-regulated protein (ORP150) functions as a novel molecular chaperone in MDCK cells.

To assess the participation of the 150-kDa oxygen-regulated protein (ORP150) in protein transport, its function in Madin-Darby canine kidney (MDCK) cells was studied. Exposure of MDCK cells to hypoxia resulted in an increase of ORP150 antigen and increased binding of ORP150 to GP80/clusterin (80-kDa glycoprotein), a natural secretory protein in this cell line. In ORP150 antisense transformant MDCK cells, GP80 was retained within the endoplasmic reticulum after exposure to hypoxia. Metabolic labeling showed the delay of GP80 maturation in antisense transformants in hypoxia, whereas its matured form was detected in wild-type cells, indicating a role of ORP150 in protein transport, especially in hypoxia. The affinity chromatographic analysis of ORP150 suggested its ability to bind to ATP-agarose. Furthermore, the ATP hydrolysis analysis showed that ORP150 can release GP80 at a lower ATP concentration. These data indicate that ORP150 may function as a unique molecular chaperone in renal epithelial cells by facilitating protein transport/maturation in an environment where less ATP is accessible.

Adenosine Triphosphate↗

PubMed2000

[A therapeutic metastasectomy of pulmonary metastases by VATS].

The use of VATS to perform diagnostic metastasectomy is uniformly accepted, but the role of therapeutic VATS metastasectomy remains controversial. We retrospectively compared the value of therapeutic metastasectomy by VATS with that by open thoracotomy in the management of pulmonary metastatic tumors. The forty-six patients who underwent a complete metastasectomy of pulmonary metastatic tumors were divided into groups: one group in which metastasectomy was performed by VATS (VATS group; 23 cases, 25 operations) and another group in which metastasectomy was performed by open thoracotomy (Thoracotomy group 23 cases, 26 operations). Here, complete metastasectomy means compete resection of all tumors, which were detected by preoperative high resolution computed tomography in both groups and also by intraoperative manipulation in the thoracotomy group, without positive lesions of the surgical margin. The groups were matched with respect to preoperative clinical characteristics (age, sex, primary lesion, disease-free interval) and histological findings (maximum tumor size, number of metastatic tumors, minimum distance between surgical margin and tumor edge). The cumulative survival one-year and three-year rates were 83.5 and 83.5% in the VATS group, and 89.5 and 77.5% in the thoracotomy group, respectively. The cumulative one-year and three-year non-recurrence rates were 72.3 and 68.0% in the VATS group and 83.9 and 63.8% in the thoracotomy group, respectively. There were no significant differences between the two groups. We conclude that pulmonary metastasectomy by VATS can be used safely not only as a diagnostic but also therapeutic tool if complete resection is done following diagnosis by preoperative high resolution computed tomography.

Aged↗

PubMed1999

Evolution of cyclic sexual reproduction under host-parasite interactions.

Alternate changes of sexual and asexual generations was studied theoretically by numerical analyses, from the viewpoint of host-parasite infective interactions. The host species was considered a diploid organism, characterized by two loci determining parasite resistance type and sexual strategy, between which a linkage exists to a certain degree. The sexual reproductive strategy was assumed to be determined by three alleles: asexual, complete sexual and cyclic sexual alleles. The effect of the parasites was represented by decreasing fitness functions of each host-type frequency. Numerical analyses of various linkages between genes and frequency dependence of host fitness revealed that the dynamics varied depending on whether the cyclic sexual allele was dominant or recessive against the complete sexual allele. When the cyclic sexual allele was dominant, the cyclic sexual strain persisted under intermediate frequency dependence of host fitness. On the other hand, when the cyclic sexual allele was recessive, it always tended to spread and to be maintained in the population. In such situations, both complete and cyclic sexual strains coexist, but the asexual strain is lost.

Alleles↗

PubMed1999

Thioredoxin-dependent redox regulation of p53-mediated p21 activation.

Thioredoxin (TRX) is a dithiol-reducing enzyme that is induced by various oxidative stresses. TRX regulates the activity of DNA-binding proteins, including Jun/Fos and nuclear factor-kappaB. TRX also interacts with an intranuclear reducing molecule redox factor 1 (Ref-1), which enhances the activity of Jun/Fos. Here, we have investigated the role of TRX in the regulation of p53 activity. Electrophoretic mobility shift assay showed that TRX augmented the DNA binding activity of p53 and also further potentiated Ref-1-enhanced p53 activity. Luciferase assay revealed that transfection of TRX enhanced p53-dependent expression of p21 and further intensified Ref-1-mediated p53 activation. Furthermore, Western blot analysis revealed that p53-dependent induction of p21 protein was also facilitated by transfection with TRX. Overexpression of transdominant negative mutant TRX (mTRX) suppressed the effects of TRX or Ref-1, showing a functional interaction between TRX and Ref-1. cis-Diamminedichloroplatinum (II) (CDDP) induced p53 activation and p21 transactivation. The p53-dependent p21 transactivation induced by CDDP was inhibited by mTRX overexpression, suggesting that TRX-dependent redox regulation is physiologically involved in p53 regulation. CDDP also stimulated translocation of TRX from the cytosol into the nucleus. Hence, TRX-dependent redox regulation of p53 activity indicates coupling of the oxidative stress response and p53-dependent repair mechanism.

Carbon-Oxygen Lyases↗

PubMed1999

Kainic acid-induced seizure upregulates Na(+)/myo-inositol cotransporter mRNA in rat brain.

A major organic osmolyte, myo-inositol protects cells from perturbing effects of high intracellular concentrations of electrolytes. Myo-inositol is accumulated into cells through Na(+)/myo-inositol cotransporter (SMIT). In order to investigate the regulation of SMIT in generalized seizure, we employed Northern blot analysis and in situ hybridization to study the changes in SMIT mRNA expression in kainic acid-injected rats. Northern blot analysis demonstrated that SMIT mRNA began to increase in the brain 2 h after onset of seizure, and peaked at 12 h. In situ hybridization revealed rapid increase of SMIT mRNA (2 h of seizure) in the CA3 hippocampal pyramidal cells and in the dentate granular cells. Then, at 4-6 h SMIT mRNA expression was observed in the other limbic structure such as amygdala and piriform cortex. Finally, in neocortex and in CA1 pyramidal cells, SMIT mRNA was slowly increased and peaked at 12 h. Microautoradiogram demonstrated that cells expressed SMIT mRNA were mainly neurons. These results suggest that SMIT mRNA is upregulated by kainic acid-induced seizure primarily in structures involved in seizure activity.

Animals↗

PubMed1999

Extended survival of a porcine mitral bioprosthesis for 23 years: report of a case.

Limited durability is the major drawback of bioprosthetic valves, few of which survive for as long as 20 years. We report herein the case of a patient we recently encountered in whom a bioprothesis lasted for 23 years. To our knowledge, this is only the second case of such long survival. The patient was a 56-year-old man who was urgently admitted to our hospital with acute mitral regurgitation, 23 years after undergoing mitral valve replacement with a porcine bioprosthesis. Acute leaflet tears were found to be the cause of the mitral incompetence and the xenograft was successfully replaced with a mechanical valve. We believe that when reoperation is thought to carry a low risk, prophylactic surgery might be justified, even in patients without symptoms.

Bioprosthesis↗

PubMed1999

Visualization of esophageal non-Hodgkin's lymphoma with Ga-67 scintigraphy.

Although non-Hodgkin's lymphoma of the gastrointestinal tract is common, primary esophageal lymphomas represent less than 1% of all gastrointestinal tumors. We report a case of primary non-Hodgkin's lymphoma of the esophagus. Ga-67 scintigraphy showed characteristic intense accumulation in the esophageal wall. The histopathology belonged to the category of mucosa-associated lymphoid tissue lymphoma.

Citrates↗

PubMed1999

New simple technique for hepatic parenchymal resection using a Cavitron Ultrasonic Surgical Aspirator and bipolar cautery equipped with a channel for water dripping.

We have developed a new technique to resect hepatic parenchyma without inflow occlusion by using the Cavitron Ultrasonic Surgical Aspirator (CUSA) and bipolar cautery with a saline irrigation system. The significance of this method in hepatectomy was analyzed in comparison with historical control of hepatectomy using Pringle's maneuver. An ordinary bipolar cautery was remodeled with an infusion line to bring saline droplets down the inner surface of one arm of the tweezers through an opening about 1.5 cm proximal to its tip. The optimal flow rate of saline was approximately one drop per second. The power of bipolar cautery was adjusted to 50 watts. When the tweezer blades were approximated to 1 or 2 mm, saline droplets were directed to the tip of tweezers and could be immediately evaporated. After sonicating parenchymal cells, the tissue of small branches of Glisson's tree or small tributaries of the hepatic vein were coagulated by bipolar cautery. The coagulated cords were then easily cut by scissors. The impact of this technique on ordinary liver resections was evaluated by analyzing the postoperative clinical course in relation to the hepatic functional reserve necessary for major hepatectomy, duration of hepatectomy, and intraoperative blood loss. Hepatic resection without vascular occlusion using this technique could decrease the morbidity in patients who have less hepatic functional reserve. It could also decrease intraoperative blood loss. This new technique effectively decreased the surgical load of the remnant liver during parenchymal resection by avoiding ischemic stress. Consequently it extends the safety limits of major hepatectomy.

Electrocoagulation↗

PubMed1999

Management of adrenal metastasis of hepatocellular carcinoma by asynchronous resection of bilateral adrenal glands.

We report on a 65-year-old man who received asynchronous bilateral adrenalectomy for adrenal metastasis of hepatocellular carcinoma. Fifteen months after curative resection of right hepatic lobe for hepatocellular carcinoma, a metastatic lesion of the left adrenal gland was detected and left adrenalectomy was performed. Ten months after the second operation, a metastatic lesion in the right adrenal gland, associated with tumor thrombus in the inferior vena cava, was revealed. Transcatheter arterial embolization of the arteries feeding the metastatic tumor was performed, but its effects were incomplete. As there was the tumor thrombus in the inferior vena cava and no other intrahepatic recurrence or extrahepatic metastasis was found, resection of the right adrenal gland with tumor thrombus, without the employment of veno-venous bypass, was performed, followed by postoperative hormonal supplementation. Changes in the patient's alpha-fetoprotein level were clinically useful for the detection of the metastatic lesions and the evaluation of therapeutic effects. Metastasis to adrenal gland from hepatocellular carcinoma should be actively managed, and the appropriate surgical treatment selected, if intrahepatic recurrence and/or other extrahepatic metastasis are controlled. To achieve higher curability and better outcome in patients with bilateral adrenal metastasis of hepatocellular carcinoma, bilateral total adrenalectomy is indicated, accompanied by effective postoperative hormonal supplementation.

Adrenal Gland Neoplasms↗

PubMed1999

Secondary myeloid/natural killer cell precursor acute leukemia following essential thrombocythemia.

The de novo leukemic transformation of essential thrombocythemia is a rare event, and usually associated with previous treatments. We describe a patient who received treatments with nitrosourea for long-standing essential thrombocythemia and subsequently developed extramedullary tumors, tentatively diagnosed as lymphoblastic lymphoma. Combination chemotherapy was initially successful, but relapsed with marked bone marrow involvement. Surface marker analysis revealed that the tumor cells had CD5, CD7, CD33, CD34, and CD56 antigens but lacked other T-cell, and B-cell markers. Immunogenotypical studies revealed germline configurations for both T-cell receptors and immunoglobulin genes. These clinical and phenotypical features are consistent with a myeloid/natural killer cell precursor leukemia, a recently proposed distinct clinical entity. To our knowledge, this is the first report of secondary leukemia of myeloid/ natural killer cell precursor origin, and suggest that myeloid/natural killer cell precursor might be a potent target of therapy-related leukemia.

Antigens, CD↗

PubMed1999

Hepatocyte growth inhibitory factor derived from HTLV-I(+) T-cell line is identical to IL-6.

We previously reported that the culture supernatant of the human T-cell leukemia virus (HTLV-I) infected-T-cell line--ATL-2--included factor(s), which had an inhibitory effect on epidermal growth factor (EGF)-stimulated proliferation of primary cultured rat hepatocytes. After crude purification, we arbitrarily named it hepatocyte growth inhibitory factor (HGI). In this study, we further purified HGI and determined its amino acid sequence. For purification, we used 4-steps column chromatography and SDS-PAGE. The purified proteins consisted of two bands of 20 and 27 kDa in SDS-PAGE analysis. Protein extracted from each band had an inhibitory effect on rat hepatocyte growth. Amino acid analysis of the purified 20 kDa band revealed that the 34 amino acids were identical to those of IL-6. The inhibitory effect of the factor was neutralized by an anti IL-6 neutralizing antibody. Using Western blot analysis of HGI, an anti IL-6 antibody recognized both 20 and 27 kDa bands. Consequently HGI was determined to be identical to IL-6, which occurred in higher levels in the sera of adult T-cell leukemia (ATL) patients.

Aged↗

PubMed1999

Differential regulation of adenine nucleotide translocators by hypertonicity in the brain.

To determine the gene(s) induced by hypertonicity in the brain, we performed a differential display analysis using RNA isolated from isotonic and hypertonic rat astrocytes. One cDNA rapidly up-regulated by hypertonicity was isolated, and the DNA sequence revealed that it was identical to adenine nucleotide translocator (ANT)2. ANT2 protein exchanges intramitochondrial ATP for cytoplasmic ADP. Among three ANT isoforms, only ANT2 mRNA was up-regulated markedly from 1 to 4 h after exposure to hypertonicity. Induction of the mRNA did not require de novo protein synthesis. Furthermore, ADP translocase activity in mitochondria of astrocytes was increased significantly by hypertonicity. To see the localization and regulation of ANT2 mRNA in the brain, we performed in situ hybridization of rat brain after intraperitoneal injection of a high concentration of NaCl. Although there were only weak signals in the control, intense hybridization signals were seen in hypertonic rat whole brain. Microscopic examination showed that ANT2 signals were present in the neurons, as well as glial cells. These results suggest that ANT2 may play a role in brain cells to adapt to the hypertonic environment.

Adenosine Diphosphate↗

PubMed1999

Neuroprotective role of Na+/myo-inositol cotransporter against veratridine cytotoxicity.

Na+/myo-inositol cotransporter has been shown to protect cells from the perturbing effects of hypertonic stress by the accumulation of myo-inositol. Here we report a regulatory mechanism for the cotransporter. Induction of myo-inositol cotransporter mRNA was observed after exposure to veratridine, a voltage-gated sodium channel opener. The veratridine-elicited induction was inhibited when Na+ was eliminated from the bath, although calcium chelation failed to modify the gene expression. Veratridine evoked an accumulation of Na+ in the cells, which paralleled the abundance of the mRNA. These results strongly suggested that an increase in Na+ influx due to sodium channel opening affected transcription of the cotransporter gene. Activity of the myo-inositol cotransporter was also up-regulated after veratridine exposure. To clarify the possible roles of myoinositol accumulation under veratridine exposure, we next examined the neurotoxic effects of veratridine when myo-inositol uptake was blocked. Neither 30 microM veratridine nor 500 microM 2-O,C-methylene myo-inositol, a competitive inhibitor of myo-inositol, elicited apparent cytotoxicity. However, a combination of these agents markedly increased cytotoxicity in culture, suggesting that an adequate amount of myo-inositol was necessary when the cells were stimulated with veratridine.

Carrier Proteins↗

PubMed1999

High water intake ameliorates tubulointerstitial injury in rats with subtotal nephrectomy: possible role of TGF-beta.

BACKGROUND: It has been shown that tubulointerstitial injury correlates well with a decline of renal function. In this study, we investigated the effect of high water intake (HWI) on functional and structural parameters in rats with subtotal nephrectomy. METHODS: Two weeks after the ablative procedure, rats were divided into two groups. One group received the treatment with HWI (3% sucrose added to drinking water) for eight weeks. Functional parameters were compared with sham-operated control (CONT) or nephrectomized rats without treatment (NX). Remnant kidneys were then assessed histologically for evidence of interstitial fibrosis and glomerulosclerosis. RESULTS: Creatinine clearance was significantly improved in HWI rats compared with NX rats. Simultaneously, urinary protein was also significantly reduced in HWI rats. HWI predominantly ameliorated interstitial lesions and, to a lesser extent, glomerular lesions. Northern blot analysis demonstrated that transforming growth factor-beta (TGF-beta) mRNA expression was significantly suppressed in HWI rats. In situ hybridization revealed that HWI suppressed TGF-beta mRNA expression mainly in the outer medulla. Fibronectin mRNA was also reduced by the HWI treatment. The changes in TGF-beta and fibronectin mRNA were in parallel with Na+/myo-inositol cotransporter (SMIT) mRNA, which is regulated by extracellular osmolarity. Immunohistochemistry demonstrated that protein expression of TGF-beta and fibronectin coincided with the mRNA expression. CONCLUSION: These results suggest that HWI reduces TGF-beta mRNA expression in medullary interstitium and ameliorates tubulointerstitial injury in rats with reduced renal mass.

Animals↗

PubMed1999

Involvement of histone phosphorylation in thymocyte apoptosis by protein phosphatase inhibitors.

Incubation of rat thymocytes with the inhibitors of protein phosphatase such as calyculin A and okadaic acid resulted in an increase in DNA fragmentation. These effects were dependent on the concentration of the inhibitors and the incubation time. Analyses of the fragmented DNA revealed the production of approximately 50 kbp of DNA and a 180 bp DNA ladder. In addition, a laser scanning-microscopic analysis showed that these compounds caused nuclear condensation. Thus, these results demonstrated that protein phosphatase inhibitors induced thymocyte apoptosis. The inhibitors of protein phosphatase increased the phosphorylation of proteins of approximately 15 kDa. The phosphorylation of proteins preceded the DNA fragmentation induced by these inhibitors. Judging from acetic acid-urea-Triton X-100 gel electrophoresis, the phosphorylated proteins were histone H1 and H2A/H3. Therefore, these results suggest that phosphorylation of histones triggers the DNA fragmentation of thymocytes undergoing apoptosis.

Animals↗

PubMed1999

Response to hypertonicity in mesothelial cells: role of Na+/myo-inositol co-transporter.

BACKGROUND: During peritoneal dialysis, the peritoneal mesothelium is exposed continually to hypertonic dialysates. The purpose of this study is to see if rat mesothelial cells have an osmoregulatory mechanism to adapt to hypertonic environment. METHODS: The intracellular content of organic osmolytes was measured by HPLC methods. Myo-inositol transport activity was measured by Na+-dependent uptake of [3H]myo-inositol. mRNA abundance for the Na+/myo-inositol co-transporter (SMIT) was examined by Northern and slot-blot analyses. RESULTS: In isotonic mesothelial cells, only myo-inositol could be detected. After switching to hypertonic medium made by addition of NaCl, myo-inositol content gradually increased and peaked at 48 h after the switch. The myo-inositol content in hypertonic cells increased > 7-fold over the value in isotonic cells. The contents of betaine and glycerophosphorylcholine (GPC) also increased but were less than that of myo-inositol. Sorbitol was not accumulated in this condition. When glucose was used to increase medium osmolality, all of the four osmolytes were increased by hypertonicity (myo-inositol > sorbitol > GPC > betaine). Thus, myo-inositol is the most abundant osmolyte in the mesothelial cells. Na+-dependent myo-inositol uptake in hypertonic cells was approximately 7-fold the uptake in isotonic cells, reaching a maximum 16 h after switching to a hypertonic medium. The uptake rate increased as medium osmolality increased from 300 to 500 mosm/kg. SMIT mRNA rapidly increased after increasing medium osmolality, reaching a maximum 8 h after the switch. The relative increase in the mRNA abundance was approximately 11 times isotonic levels. CONCLUSIONS: Mesothelial cells respond to extracellular hypertonicity by increasing SMIT mRNA abundance, myo-inositol transport activity and accumulating myo-inositol into the cells.

Animals↗