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Biomedical subjects

Hiroshi Miyazaki

Publications and source records attributed to Hiroshi Miyazaki.

At least 19 recordsLinked to original sources
PubMed2006

Carbonic-adsorbent AST-120 reduces overload of indoxyl sulfate and the plasma level of TGF-beta1 in patients with chronic renal failure.

BACKGROUND: We previously reported a significant increase in plasma TGF-beta1 in patients with chronic renal failure (CRF). Progression of CRF may be caused by persistent renal production of TGF-beta1. In CRF rat models, an oral carbonic absorbent (AST-120) reduces the expression of the TGF-beta1 gene in the kidney, and delays the progression of CRF, in part by alleviating the overload of indoxyl sulfate. The aim of this study was to evaluate the effect of AST-120 on plasma levels of indoxyl sulfate and TGF-beta1 in CRF patients. METHODS: Ten CRF patients (aged 59.3 +/- 9.5 years, 5 men, serum creatinine 4.37 +/- 1.72 mg/dl) were enrolled in this study. All patients maintained a regular dietary therapy and the same medication throughout the study. AST-120 was added at a dose of 6 g/day. Parameters including the slope of the reciprocal of the serum creatinine-time plot, plasma indoxyl sulfate level, and plasma and urinary levels of TGF-beta1 were compared before and after the treatment with AST-120. The mean observation periods before and after the treatment were 9.7 +/- 2.8 and 6.5 +/- 2.9 months, respectively. RESULTS: Administration of AST-120 significantly reduced the plasma levels of indoxyl sulfate (1.42 +/- 1.50 vs. 1.26 +/- 1.40 mg/dl, P < 0.05) and TGF-beta1 (17.9 +/- 7.2 vs. 10.6 +/- 4.7 ng/ml, P < 0.05) and improved the slope of the reciprocal of serum creatinine (-0.061 +/- 0.041 vs. -0.032 +/- 0.055 dl/mg/year, P < 0.05). CONCLUSIONS: These results support the notion that indoxyl sulfate and TGF-beta1 may be involved in the progression of CRF, and that the oral adsorbent AST-120 may suppress the progression, at least in part, by reducing overproduction of TGF-beta1.

Adsorption↗
PubMed2006

Characteristic air temperature distributions observed in summer and winter in urban area in Japan.

The air temperature distributions in August (summer) and December (winter) were measured in an approximately 15 x 15-km urban area in Hyogo Prefecture, Japan, in order to study the spatial distribution of the air temperature and to propose effective measures against the heat island phenomenon. The air temperature was measured mainly by using thermometer shelters installed in an elementary school and a junior high school. The characteristic air temperature distribution depended on the season. The air temperature was higher inland than in the coastal region in August but was higher in the coastal region in December. The air temperature index indicated that the area where higher air temperatures would most likely appear was 5 to 10 km inland from the coast in August and around the coast in December. The seasonal air temperature distribution was presumably due to the strength of solar radiation and anthropogenic exhaust heat.

Environmental Monitoring↗
PubMed2006

Highly sensitive quantification of 7alpha-hydroxy-4-cholesten-3-one in human serum by LC-ESI-MS/MS.

We describe a highly sensitive and specific method for the quantification of serum 7alpha-hydroxy-4-cholesten-3-one (C4), which has been used as a biomarker for bile acid biosynthesis. This method is based upon a stable isotope dilution technique by liquid chromatography-tandem mass spectrometry (LC-MS/MS). C4 was extracted from human serum (2-50 mul) by a salting-out procedure, derivatized into the picolinoyl ester (C4-7alpha-picolinate), and then purified using a disposable C(18) cartridge. The resulting picolinoyl ester derivative of C4 was quantified by LC-MS/MS using the electrospray ionization mode. The detection limit of the C4 picolinoyl ester was found to be 100 fg (signal-to-noise ratio = 10), which was approximately 1,000 times more sensitive than the detection limit of C4 with a conventional HPLC-ultraviolet method. The relative standard deviations between sample preparations and between measurements by our method were calculated to be 5.7% and 3.9%, respectively, by one-way layout analysis. The recovery experiments were performed using serum spiked with 20.0-60.0 ng/ml C4 and were validated by a polynomial equation. The results showed that the estimated concentration with 95% confidence limit was 23.1 +/- 2.8 ng/ml, which coincided completely with the observed X(0) +/- SD = 23.3 +/- 1.0 ng/ml with a mean recovery of 93.4%. This method provides highly reliable and reproducible results for the quantification of C4, especially in small volumes of blood samples.

Calibration↗
PubMed2006

Isolated splenic vein thrombosis secondary to splenic metastasis: a case report.

A 49-year-old, previously healthy woman sought treatment for abdominal pain. Colonoscopy revealed ascending colon cancer. Computed tomography and angiography showed splenic metastasis and thrombosis extending from the splenic vein to the portal vein. She underwent right hemicolectomy, splenectomy, and distal pancreatomy. Histological findings showed no malignant cell in the splenic vein which was filled with organizing thrombus. We postulate the mechanism of splenic vein thrombosis in our case to be secondary to the extrinsic compression of the splenic vein by the splenic metastasis or by the inflammatory process produced by the splenic metastasis. In conclusion, we suggest that splenic metastasis should be added to the list of differential diagnosis which causes splenic vein thrombosis. In the absence of other sites of neoplastic disease, splenectomy seems to be the preferred therapy because it can be performed with low morbidity and harbors the potential for long-term survival.

Adenocarcinoma↗
PubMed2006

Down-regulation of CXCL5 inhibits squamous carcinogenesis.

We report a novel role for the CXC-chemokine, CXCL5, in the proliferation and invasion of head and neck squamous cell carcinoma (HNSCC). Previously, we reported transcriptional up-regulation of CXCL5 in metastatic cells. In this study, we provide biological validation of these findings and show that CXCL5 is intimately involved in tumor cell proliferation, migration, and invasion. Cells derived from a lymph node metastasis, but not from a synchronous primary tumor, secreted CXCL5 as judged by Western blotting of conditioned media. We used RNA interference to generate cell lines (shL5) in which CXCL5 expression was greatly reduced, and tested whether this modulated the cell phenotype. shL5 cells showed decreased proliferation compared with cells harboring nontargeting control sequences. In addition, we found that the ability of shL5 cells to migrate and invade in vitro through a basement membrane substitute was greatly impaired compared with control cells. Finally, whereas control cells were highly tumorigenic in nude mice, the tumorigenic potential in vivo of shL5 cells was found to be ablated. Taken together, these data suggest that CXCL5 production contributes to both enhanced proliferation and invasion of squamous cell carcinomas and that targeting of chemokine pathways may represent a potential therapeutic modality for these lesions.

Carcinoma, Squamous Cell↗
PubMed2006

Strangulated hernia through a defect of the broad ligament and mobile cecum: a case report.

We report a case of 28-year-old woman presenting with small bowel obstruction. She had neither prior surgery nor delivery. An upright abdominal radiograph revealed several air-fluid levels in the small bowel in the midabdomen and the pelvic cavity. Computed tomography demonstrated a dilated small bowel loop in the Douglas's fossa,but no definite diagnosis could be made. Supportive therapy with draining the intestinal fluid by a long intestinal tube did not result in improvement,which suggested the possibility of a strangulated hernia. Exploratory laparotomy revealed mobile cecum and a 20-cm length of the ileum herniated into a defect of the right broad ligament. As a gangrenous change was recognized in the incarcerated bowel, its resection was carried out,followed by end-to-end anastomosis and closure of the defects of the broad ligament. The postoperative course was uneventful. Intestinal obstruction is a very common cause for presentation to an emergency department,while internal hernia is a rare cause of obstruction. Among internal hernias, those through defects of the broad ligament are extremely rare. Defects of the broad ligament can be either congenital or secondary to surgery, pelvic inflammatory disease,and delivery trauma. In conclusion, we emphasize that hernia of the broad ligament should be added to the list of differential diagnosis for female patients presenting with an intestinal obstruction. Early diagnosis and surgical repair reduce morbidity and mortality from strangulation.

Adult↗
PubMed2006

Inhibition of basic leucine zipper transcription is a major mediator of atrial dilatation.

OBJECTIVE: Atrial fibrillation is the most prevalent clinically significant cardiac arrhythmia. Atrial dilatation, a predictor of atrial fibrillation, is thought to result from increased ventricular pressure. However, the underlying molecular mechanisms responsible for atrial dilatation are largely unknown. Here we sought to examine whether the expression of a basic leucine zipper inhibitor protein, JDP2, in the heart is sufficient for the generation of atrial dilatation. METHODS: A tetracycline-regulated transgene was used to express JDP2 specifically in the mouse heart. Mice hearts were dissected and subjected to Northern and Western analysis, or analyzed by ECG recording and echocardiography. Regulation of gene expression was studied using electromobility shift assays and luciferase gene reporter analysis. RESULTS: Expression of JDP2 resulted in massive bi-atrial dilatation, defects in conduction, and a lethal phenotype. These effects were developmentally independent, acquired during adulthood, and were reversible upon abolishing of JDP2 expression. Connexin 40 and myosin light chain 2a expression were identified as potential target genes. CONCLUSION: Expression of basic leucine zipper transcription inhibitors is sufficient to results in atrial dilatation. This dilatation is acquired postnatally and is reversible. Thus, basic leucine zipper transcription inhibitors may be a relevant therapeutic target for preventing atrial dilatation and atrial fibrillation.

Activating Transcription Factor 3↗
PubMed2006

Thrombopoietin in postoperative thrombocytopenia following living donor hepatectomy.

Thrombocytopenia is a frequent finding following living donor hepatectomy. It appears more pronounced in right graft donors than in left graft donors. This study analyzed postoperative thrombocytopenia in 20 living liver donors and examined the change of endogenous thrombopoietin (TPO) in its recovery. Platelet count, TPO level, fibrinogen degradation product (FDP), and D-Dimer were measured before surgery and on postoperative days (PODs) 1, 2, 3, 5, 7, and 14. Concurrently, liver and spleen volumes were calculated by computed tomography. Platelet count on POD 3 was significantly lower in right graft donors than in left graft donors (13.0 +/- 3.7 x 10(4)/microL vs. 16.8 +/- 4.0 x 10(4)/microL, P = 0.039) but recovered by POD 7 in all donors. Postoperative elevations of FDP and D-Dimer were significantly higher in right graft donors than in left graft donors. TPO level rose immediately after surgery, peaked on POD 5 in left graft donors and on POD 7 in right graft donors, and fell nearly to preoperative levels by POD 14. Postoperative TPO level per liver volume was significantly higher in right graft donors than in left graft donors. In conclusion, thrombocytopenia following living donor hepatectomy resolved within the first week regardless of graft type and was mainly associated with increasing consumption of circulating platelets, possibly due to intrahepatic and splenic congestion. With a reduced number of circulating platelets, TPO level rapidly increases. Also, with reduced consumption of platelets related to recovery from surgery, thrombocytopenia should resolve. As a consequence, TPO level would be expected to fall.

Adult↗
PubMed2006

An uncommon case of diabetic mastopathy in type II non-insulin dependent diabetes mellitus.

Diabetic mastopathy is an uncommon tumor-like proliferation of fibrous tissue of the breast that usually occurs in a patient who has suffered from type I diabetes mellitus of long duration. Here we report a rare case of diabetic mastopathy that occurred in type II non-insulin dependent diabetes mellitus. This patient was a 63-year-old postmenopausal woman. Mammography, ultrasonography and MR imaging could not distinguish it from breast cancer. Although the core needle biopsy specimen showed fibrosis without evidence of malignancy, excisional biopsy was performed. Histological findings demonstrated typical diabetic mastopathy with keloid-like fibrosis, perivascular lymphocytic infiltration, and lymphocytic lobulitis without evidence of malignancy. These lymphocytes were composed predominantly of B-cells. Five months after surgical biopsy, a nodular formation approximately 4 cm in diameter recurred adjacent to the resected end of the biopsy.

Biopsy, Needle↗
PubMed2006

Role of Porphyromonas gingivalis FeoB2 in metal uptake and oxidative stress protection.

Porphyromonas gingivalis, a gram-negative anaerobic bacterium, is a recognized periodontopathogen. It exhibits a high degree of aerotolerance and is able to survive in host cells, indicating that efficient oxidative stress protection mechanisms must be present in this organism. Manganese homeostasis plays a major role in oxidative stress protection in a variety of organisms; however, the transport and role of this metal in P. gingivalis is not well understood. Analysis of the genome of P. gingivalis W83 revealed the presence of two genes encoding homologs of a ferrous iron transport protein, FeoB1 and FeoB2. FeoB2 has been implicated in manganese accumulation in P. gingivalis. We sought to determine the role of the FeoB2 protein in metal transport as well as its contribution to resistance to oxygen radicals. Quantitative reverse transcriptase PCR analyses demonstrated that expression of feoB2 is induced in the presence of oxygen. The role of FeoB2 was investigated using an isogenic mutant strain deficient in the putative transporter. We characterized the FeoB2-mediated metal transport using (55)Fe(2+) and (54)Mn(2+). The FeoB2-deficient mutant had dramatically reduced rates of manganese uptake (0.028 pmol/min/10(7) bacteria) compared with the parental strain (0.33 pmol/min/10(7) bacteria) (after 20 min of uptake using 50 nM of (54)Mn(2+)). The iron uptake rates, however, were higher in the mutant strain (0.75 pmol/min/10(7) bacteria) than in the wild type (0.39 pmol/min/10(7) bacteria). Interestingly, reduced survival rates were also noted for the mutant strain after exposure to H(2)O(2) and to atmospheric oxygen compared to the parental strain cultured under the same conditions. In addition, in vitro infection of host cells with the wild type, the FeoB2-deficient mutant, and the same-site revertant revealed that the mutant had a significantly decreased capability for intracellular survival in the host cells compared to the wild-type strain. Our results demonstrate that feoB2 encodes a major manganese transporter required for protection of the bacterium from oxidative stress generated by atmospheric oxygen and H(2)O(2). Furthermore, we show that FeoB2 and acquisition of manganese are required for intracellular survival of P. gingivalis in host cells.

Aerobiosis↗
PubMed2005

Laminin alpha5 is required for dental epithelium growth and polarity and the development of tooth bud and shape.

In tooth development, the oral ectoderm and mesenchyme coordinately and reciprocally interact through the basement membrane for their growth and differentiation to form the proper shape and size of the tooth. Laminin alpha5 subunit-containing laminin-10/11 (LM-511/521) is the major laminin in the tooth germ basement membrane. Here, we have examined the role of laminin alpha5 (Lama5) in tooth development using laminin alpha5-null mouse primary dental epithelium and tooth germ organ cultures. Lama5-null mice develop a small tooth germ with defective cusp formation and have reduced proliferation of dental epithelium. Also, cell polarity and formation of the monolayer of the inner dental epithelium are disturbed. The enamel knot, a signaling center for tooth germ development, is defective, and there is a significant reduction of Shh and Fgf4 expression in the dental epithelium. In the absence of laminin alpha5, the basement membrane in the inner dental epithelium becomes discontinuous. In normal mice, integrin alpha6beta4, a receptor for laminin alpha5, is strongly localized at the basal layer of the epithelium, whereas in mutant mice, integrin alpha6beta4 is expressed around the cell surface. In primary dental epithelium culture, laminin-10/11 promotes cell growth, spreading, and filopodia-like microspike formation. This promotion is inhibited by anti-integrin alpha6 and beta4 antibodies and by phosphatidylinositol 3-kinase inhibitors and dominant negative Rho-GTPase family proteins Cdc42 and Rac. In organ culture, anti-integrin alpha6 antibody and wortmannin reduce tooth germ size and shape. Our studies demonstrate that laminin alpha5 is required for the proliferation and polarity of basal epithelial cells and suggest that the interaction between laminin-10/11-integrin alpha6beta4 and the phosphatidylinositol 3-kinase-Cdc42/Rac pathways play an important role in determining the size and shape of tooth germ.

Animals↗
PubMed2005

Growth factor-sensitive molecular targets identified in primary and metastatic head and neck squamous cell carcinoma using microarray analysis.

Polypeptide growth factors play key roles in the processes of cell migration and invasion. In this study, we have used cDNA microarrays to identify target genes whose expression is differentially modulated by the growth factors TGFbeta and EGF. HN4 and HN12 cell lines, established from primary tumor and a lymph node metastasis arising in one patient with head and neck squamous cell carcinoma, were treated with 2nM EGF or 50pM TGFbeta for 24h and extracted RNA was used to prepare labeled cDNAs which were hybridized to NCI UniGem 2.0 cDNA microarrays containing 9128 features. Results revealed constitutive overexpression of 41 genes and underexpression of 109 genes in metastatic HN12 compared to HN4 under conditions of serum withdrawal. Furthermore, TGFbeta treatment resulted in relative upregulation of 53 genes and downregulation of 91 genes in HN12 compared with HN4, whereas cells treated with EGF showed relative upregulation of 67 genes and downregulation of 113 genes. Partial overlap was found between TGFbeta and EGF-modulated gene sets. Results were verified for a subset of each category using quantitative PCR, western blotting and zymography. The data indicate that TGFbeta and EGF differentially affect gene expression in primary and metastatic HNSCC cells, and likely contribute to the invasive properties of metastatic cells through regulation of both common and specific mediators for each growth factor.

Blotting, Western↗
PubMed2005

Uncoupling of epidermal growth factor-dependent proliferation and invasion in a model of squamous carcinoma progression.

Cell lines pairs were established from a primary squamous carcinoma of tongue and a lymph node metastasis and their biological behavior characterized. HN12 cells, derived from metastatic SCC, formed tumors upon subcutaneous transplantation to athymic mice, whereas HN4, derived from a primary lesion in the same individual, were non-tumorigenic in this assay. EGF stimulated proliferation of HN4 cells; in comparison, not only were metastatic HN12 cells refractory to the stimulatory effects of this growth factor but showed inhibition at higher growth factor concentrations. However, in contrast to the effects on proliferation, EGF (10 ng/ml) readily induced HN12 cells to invade in Boyden chamber assays whereas HN4 were non-invasive under these conditions. The invasive properties of HN12 cells were apparently independent of MMP-2 activity, as levels of active MMP-2 were higher in the non-invasive cells. However, EGF stimulated MMP-9 activity in invasive cells. Additionally, HN12 cells expressed constitutively high levels of active MMP-7 and MMP-3/10. The pharmacological agents LY294002, PD098059, SP600125, or SB202190 inhibited invasion of HN12 cells, suggesting requirement for phosphoinositide 3-OH kinase- and mitogen activated protein kinase-dependent pathways in the process. The data indicate that distinct biochemical differences distinguish metastatic squamous carcinoma cells from those derived from corresponding primary tumors, resulting in their contrasting biological properties.

Animals↗
PubMed2005

Thrombopoietin in the cerebrospinal fluid of patients with aseptic and bacterial meningitis.

Despite the recent evidence of the localization of thrombopoietin (TPO) and its receptor in the central nervous system (CNS), TPO protein concentrations in the cerebrospinal fluid (CSF) remained to be clarified. We previously reported that serum TPO is increased in children with meningitis. To determine changes in TPO concentrations in the CSF by meningitis and to explore the relationship between serum and CSF TPO concentrations, we measured TPO concentrations in 110 CSF samples and 33 serum/CSF pairs from 11 bacterial meningitis, 49 aseptic meningitis, and 50 nonmeningitis children. In only 12% (13 of 110) of CSF samples (0 bacterial meningitis, 8 aseptic meningitis, and 5 controls), TPO concentrations could be determined (24.1 +/- 29.0 pg/ml). CSF TPO concentrations did not significantly differ among the three groups and did not correlate with age. TPO concentrations in all serum samples were detectable, and mean concentrations in bacterial meningitis (510.6 +/- 237.0 pg/ml) were significantly higher than those in aseptic meningitis (136.6 +/- 71.6, p < 0.01) and controls (181.3 +/- 88.3, p < 0.01). These findings suggest that TPO is not produced in the CNS of patients with meningitis and that TPO did not cross the blood-brain barrier even during meningeal infection.

Adolescent↗
PubMed2005

Expression of erythropoietin receptor-like molecule in Xenopus laevis and erythrocytopenia upon administration of its recombinant soluble form.

The regulation of hematopoiesis in non-mammalian vertebrates is poorly understood. This is partly because the structures and effects of most hematopoietic regulators have not been identified. As a first step towards studies on the key mechanism of hematopoietic regulation among phyla as well as the diversity of organisms, we have focused on amphibian hematopoiesis. A cDNA sharing the highest degree of homology with mammalian erythropoietin (EPO) receptors, tentatively named xlEPOR, was cloned from a cDNA library of Xenopus laevis immature erythrocytes. The comparative identities of the deduced entire amino acid sequence to mammalian EPO receptors were quite low, although functional domains indispensable for erythropoietic activities were found in the molecule. Northern analysis revealed that xlEPOR were expressed in peripheral blood cells. In the peripheral blood of phenylhydrazine-treated adult Xenopus, immature erythrocytes expressing xlEPOR were identified by in situ hybridization and immunostaining with polyclonal antibodies to xlEPOR. To confirm the biological functions of this molecule, the extracellular domain of xlEPOR (i.e., soluble xlEPOR) was administered to adult Xenopus by consecutive intracardiac injection. The peripheral erythrocyte counts were decreased gradually; meanwhile, immature erythrocytes appeared in the circulation, demonstrating that xlEPOR plays a significant physiological role in erythropoiesis in Xenopus laevis.

Amino Acid Sequence↗
PubMed2005

Behavior of caveolae and caveolin-3 during the development of myocyte hypertrophy.

Recent studies have indicated that caveolae are enriched in a variety of signaling molecules, some of which are associated with cardiomyocyte hypertrophy. Caveolin-3, a major constituent of cardiac caveolae, has been suggested to interact with several signaling molecules. We investigated the morphologic changes of caveolae and caveolin-3 expression in hypertrophied cardiomyocytes induced by an alpha1-adrenergic agonist. Cultured rat neonatal cardiomyocytes were used for the experiments. Phenylephrine induced cellular hypertrophy associated with an increase of the number of caveolae and an up-regulation of caveolin-3. Although PMA increased the number of caveolae and the caveolin-3 expression, the extent of these up-regulations was less than that by phenylephrine. Moreover, ionomycin increased the number of caveolae and up-regulated caveolin-3 as much as phenylephrine. Phenylephrine-induced up-regulations of caveolae and caveolin-3 expression were inhibited by BAPTA, suggesting that the intracellular Ca2+ is involved in those regulations. Inhibitors of calcineurin and Ca2+calmodulin-dependent kinase II attenuated the phenylephrine-induced up-regulation of caveolin-3. In pressure-overloaded rat hearts, caveolin-3 protein levels were increased compared with sham-operated rats. In conclusion, the number of caveolae and the expression of caveolin-3 were up-regulated in rat hypertrophied cardiomyocytes, possibly via the alterations of intracellular Ca2+ and protein kinase C.

Adrenergic alpha-1 Receptor Agonists↗
PubMed2005

Determination of thrombopoietin-derived peptides recognized by both cellular and humoral immunities in healthy donors and patients with thrombocytopenia.

Thrombopoietin (TPO) is a cytokine that promotes megakaryocytopoiesis and thrombopoiesis and is considered a drug suitable for patients with thrombocytopenia. However, unexpected severe thrombocytopenia has developed in some healthy individuals participating in phase I clinical trials with a pegylated recombinant human megakaryocyte growth factor (PEG-rHuMGDF) that contained the first 163 amino acids of endogenous TPO, which resulted in hampering the further development of clinical trials. Autoimmune responses to PEG-rHuMGDF, which cross-reacted with endogenous TPO, were suggested to be involved in this rare but severe adverse event, although the immunogenic epitopes have not yet been determined. To better understand the molecular basis of such autoimmune reactions, we investigated the reactivity of 18 TPO-derived peptides with HLA-A2-binding motifs to plasma and T cells, both from patients with thrombocytopenia (n=24) and from healthy donors (HDs) (n=24). Four peptides, including those possessing amino acids in receptor-binding sites, were preferentially reactive to plasma from at least 20% of the patients, whereas one peptide at position 101-109 was equally reactive to those of the patients and the HDs. Each of the five peptides had the ability to induce peptide-specific cytotoxic T lymphocytes (CTLs) in both groups, albeit with less frequency among the patients. More important, each of these five peptides had the ability to induce HLA-A2-restricted and peptide-specific CTL activity reactive to cells that produce TPO. These results may provide new insights to gain a better understanding of autoimmune reactions to TPO.

Adult↗