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Biomedical subjects

H Miyazaki

Publications and source records attributed to H Miyazaki.

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

Serum antioxidant micronutrients and the risk of oral leukoplakia among Japanese.

A population-based case-control study was designed for the investigation of any association between serum micronutrient levels and oral leukoplakia. Out of a total of 9536 subjects over the age of 40 years who participated in the oral mucosal screening programme in Tokoname city, 48 cases detected with oral leukoplakia (38 male:10 female) were recruited. For each case, four controls matched by age and sex were selected from the same cohort. We examined the fasting serum levels of retinol, alpha-tocopherol, zeaxanthin and lutein, cryptoxanthin, lycopene and carotenoids (alpha-carotene and beta-carotene) by high-performance liquid chromatography. Among males with leukoplakia mean serum lycopene and beta-carotene levels (0.175+/-0.202, 0.357+/-0.295 micromol/l) were significantly lower than those of controls (0.257+/-0.252, 0.555+/-0.408 micromol/l) (P<0.05, P<0.005). Logistic regression analysis with leukoplakia as the dependent variable showed that high serum levels of beta-carotene were related to low risk of oral leukoplakia (odds ratio 0.160, 95% C.I.: 0.029-0.866, P<0.05). There were no significant differences in any of the serum nutrients estimated in female subjects. Our results suggest for the first time that high serum levels of beta-carotene may provide protection against oral precancer for the Japanese male.

Adult↗
PubMed2000

Regulation of cellular functions by nucleoside diphosphate kinases in mammals.

The role of nucleoside diphosphate (NDP) kinases in cell growth, differentiation, and tumor metastasis in relation to signal transduction was investigated. The essential role of NDP kinase in cell growth was validated by coupling between reduced NDP kinase levels, induced by antisense oligonucleotides, and the suppression of proliferative activity of a cultured cell line. In addition, because NDP kinase levels are often enhanced with development and differentiation, as has been demonstrated in postmitotic cells and tissues, such as the heart and brain, we further examined this possibility using the bone tissue (osteoblasts) and a cultured cell line PC12D. The enhanced NDP kinase accumulation was demonstrated in the matured osteoblasts in vivo and in vitro by immunohistochemistry. In PC12D cells, neurite outgrowth took place in NDP kinase beta-transfected clones without differentiation inducers, which was accompanied by prolongation of doubling time. Neurite outgrowth, triggered by nerve growth factor and a cyclic AMP analog, was down-regulated upon forced expression of inactive mutant NDP kinase by virtue of a dominant negative effect. NDP kinase alpha-transfected rat mammary adenocarcinoma cells (MTLn3) and nm23-H2-transfected human oral squamous cell carcinoma cells (LMF4) manifested reduced metastatic potential and were associated with an altered sensitivity to environmental factors, such as motility and growth factors. NDP kinase alpha, compared to NDP kinase beta, was involved in a wide variety of the cellular phenomena examined. Taken together, NDP kinase isoforms appear to elicit both their own respective and common effects. They may have an ability to lead cells to both proliferative and differentiated states by modulating responsiveness to environmental factors, but their fate seems to depend on their surrounding milieu.

Amino Acid Sequence↗
PubMed2000

Expression of hepatic thrombopoietin mRNA in primary cultured hepatocytes and in rats with acute liver injury or bone marrow suppression with or without cirrhosis.

BACKGROUND AND AIMS: The main causes of thrombocytopenia in cirrhosis are thought to be platelet destruction and the reduction of thrombopoietin (TPO) expression in the liver. The mechanisms by which levels of TPO mRNA are regulated in cirrhosis have not been elucidated. In this study, we investigated some possible mechanisms. METHODS: We used three experimental models: bone marrow suppression, acute liver injury and primary cultured hepatocytes. We used northern blots to assess the kinetics of TPO mRNA expression in the livers of irradiated rats (with and without cirrhosis) in acute liver injury and in primary cultured hepatocytes treated with hepatotoxin or cytokines. RESULTS: Although the bone marrow was hypocellular, there was no apparent enhancement of TPO mRNA expression in the irradiated rats with cirrhotic livers compared with the unirradiated rats with cirrhotic livers. There were no conspicuous changes in hepatic TPO mRNA expression between the livers of the control rats and the three models of acute liver injury. There were no conspicuous changes in the levels of TPO mRNA between control hepatocytes and hepatocytes treated with hepatotoxin or cytokines. CONCLUSIONS: Our results suggest that bone marrow is not a regulator of hepatic TPO production in cirrhosis. The reduced TPO mRNA expression found in cirrhotic rats may not result merely from serious cellular damage; it may be associated with cirrhosis-specific regulatory mechanisms for the expression of the TPO gene. Further studies are needed to search for other factors that may induce reduced TPO expression.

Acute Disease↗
PubMed2000

Glial cell line-derived neurotrophic factor modulates ischemia-induced tyrosine hydroxylase expression in rat hippocampus.

Recently, we have reported that glial cell line-derived neurotrophic factor (GDNF), which supports the survival of dopaminergic neurons, prevents delayed neuronal death in the hippocampal CA1 region induced by transient forebrain ischemia. In the present study, we examined the role of GDNF in the expression of tyrosine hydroxylase (TH) mRNA induced by transient forebrain ischemia in rats. The expression of TH mRNA was increased in a time-dependent manner, with a significant increase in 24 h to 7 days, in the hippocampus after induction of transient forebrain ischemia, as determined using the reverse transcription and polymerase chain reaction method. Although it has been suggested that the increase of dopamine beta-hydroxylase mRNA expression correlates with the activation of noradrenergic neurons, no increase of dopamine beta-hydroxylase mRNA in the hippocampus was observed in our system. Western blot analysis revealed that TH protein, but not dopamine beta-hydroxylase protein, was produced in a time-dependent manner in the hippocampus during the ischemia. Interestingly, the induction level of TH mRNA was reduced by intrahippocampal microinjection of GDNF (1.0 microg), and this local GDNF treatment also reduced the increase of TH-like immunohistochemistry-positive terminals in the hippocampus. In contrast, local GDNF treatment of normal rats increased the TH mRNA expression at 6-12 h. These findings suggest that GDNF protects against neuronal degeneration including delayed neuronal death in the hippocampal CA1 region by modulating the expression levels of TH mRNA and protein.

Animals↗
PubMed2000

Assessment of drug concentrations in tears in therapeutic drug monitoring: I. Determination of valproic acid in tears by gas chromatography/mass spectrometry with EC/NCI mode.

A rapid and sensitive method for the quantitation of valproic acid in tears has been developed using gas chromatography/electron capture negative chemical ionization/mass spectrometry. Valproic acid was converted directly into its pentafluorobenzyl ester derivative without the need to perform any extraction from the biologic fluid. The concentrations in tears [C]t correlated very well with those of the free form in the plasma [Cf]p and those of the total form in the plasma [Cb+f]p. The ratios between valproic acid concentrations in tears and plasma were as follows: [C]t/[Cb+f]p = 0.10 +/- 0.02; [C]t/[Cf]p = 0.57 +/- 0.11. Ratios of [C]t/[Cb+f]p were in good agreement with previously published data.

Anticonvulsants↗
PubMed2000

Cascading glia reactions: a common pathomechanism and its differentiated control by cyclic nucleotide signaling.

A pathological glia activation, stimulated by inflammatory proteins, beta-amyloid, or brain ischemia, is discussed as a common pathogenic factor for progressive nerve cell damage in vascular and Alzheimer dementia. A critical point seems to be reached, if the cytokine-controlled microglial upregulation causes a secondary activation of astrocytes which loose the negative feedback control, are forced to give up their physiological buffering function, and may add to neuronal damage by the release of nitric oxide (NO) and by promoting toxic beta-amyloid formation. A strengthening of the cyclic adenosine-5',3'-monophosphate (cAMP) signaling exerted a differential inhibition of the stimulatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) released from cultured rat microglia, but maintained the negative feedback signal IL-6; cAMP inhibited also the release of free oxygen radicals (OR) but not of NO. Reinforcement of the NO-induced cyclic guanosine monophosphate (cGMP) increase by blockade of the phosphodiesterase (PDE) subtype-5 with propentofylline counterbalanced the toxic NO action that causes with OR neuronal damage by peroxynitrate formation. In rat cultured astrocytes, a prolonged cAMP elevation favored cell differentiation, the expression of a mature ion channel patter, and an improvement of the extracellular glutamate uptake. Cyclic AMP signaling could be strengthened by PDE blockade and by raising extracellular adenosine, which stimulates A2 receptor-mediated cAMP synthesis. Via an A1 receptor-mediated effect, elevated adenosine was found to overcome a deficient intracellular calcium mobilization resulting from an impaired muscarinic signaling at pathologically decreased acetylcholine concentrations. We suggest that pharmaca, which elevate extracellular adenosine and/or block the degradation of cyclic nucleotides, may be used to counteract glia-related neuronal damage in dementing processes.

Alzheimer Disease↗
PubMed2000

Genetic analysis of azole resistance in the Darlington strain of Candida albicans.

High-level azole resistance in the Darlington strain of Candida albicans was investigated by gene replacement in C. albicans and expression in Saccharomyces cerevisiae. We sequenced the ERG11 gene, which encodes the sterol C(14)alpha-demethylase, from our copy of the Darlington strain. Both alleles contained the histidine for tyrosine substitution at position 132 (Y132H) reported in Darlington by others, but we also found a threonine-for-isoleucine substitution (I471T) not previously reported in the C. albicans ERG11. The encoded I471T change in amino acids conferred azole resistance when overexpressed alone and increased azole resistance when added to the Y132H amino acid sequence in an S. cerevisiae expression system. Replacement of one copy of ERG11 in an azole-susceptible strain of C. albicans with a single copy of the Darlington ERG11 resulted in expression of the integrated copy and a modest increase in azole resistance. The profound azole resistance of the Darlington strain is the result of multiple mutations.

Amino Acid Substitution↗
PubMed2000

Oral cancer screening as an integral part of general health screening in Tokoname City, Japan.

OBJECTIVES: To measure the attendance and compliance rates in oral mucosal screening (OMS) offered as part of a general health screen (GHS) undertaken as an organised programme in Japan. METHODS: In 1996, all adults over the age of 40 years resident in Tokoname City were invited by letter to attend a free GHS annually, conducted by the municipal cooperation and the medical and dental societies of Tokoname City. In the later years only those who attended in 1996 were reinvited. Females aged less than 39 years were also allowed to attend if they wished to participate in the GHS. The GHS consisted of completion of a self administered questionnaire to identify past and current illnesses and any medications used by the screened population coupled with a routine physical check, chest x ray, ECG, and blood and urine examination. The GHS was programmed annually during the years 1996 to 1998. All those attending the GHS were invited to participate in an OMS conducted under the same roof by a visiting dentist (n=37). A referral pathway was established for screen positives requiring follow up. RESULTS: A total of 19 305 subjects (5955 males, 13350 females; mean age 59.2 years; 7033 in 1996, 6289 in 1997, and 5983 in 1998) attended the GHS. Of those who attended the GHS, 19 056 (98.7%) attended the OMS (1.3% refused). This rate was fairly constant over the three years. Excluding repeat examinations, new cases recruited for OMS over the three years were 8723. Of those participating in OMS, 4269 (60.7%) attended all three years. In the cohorts examined, screening dentists recorded oral mucosal lesions in 5.4% in 1996, in 4.0% in 1997, and in 2.6% in 1998. Overall, this amounted to a positive detection rate of 4.1%, or 4.9% excluding repeat examinations. A higher prevalence of oral pre-cancer was recorded among male smokers. CONCLUSIONS: The overall results suggest that although compliance with attending a free GHS was low (26.2%) among Japanese subjects over 40 years of age, of those who complied 74-76% reattended annually. Hence a satisfactory participation rate can be obtained in Japan for OMS when this is coupled to a GHS conducted at the same visit.

Adult↗
PubMed2000

Effects of swimming training on three superoxide dismutase isoenzymes in mouse tissues.

The purpose of the present study was to investigate the effects of swimming training on the changes in three superoxide dismutase (SOD) isoenzymes in mice. The trained mice underwent a 6-wk swimming program (1 h/day, 5 days/wk) in water at 35-36 degrees C. Immunoreactive extracellular SOD (EC-SOD), copper- and zinc-containing SOD (CuZn-SOD), and manganese-containing SOD (Mn-SOD) contents and their mRNA abundance were determined in serum, heart, lung, liver, kidney, and gastrocnemius muscle. EC-SOD content in liver and kidney was significantly increased with training. After training, CuZn-SOD content rose significantly only in kidney but decreased significantly in heart, lung, and liver. Mn-SOD content showed a significant increase in lung, kidney, and skeletal muscle but a significant decrease in liver. In most tissues, however, the changes in SOD isoenzyme contents were not concomitant with those in their mRNA levels. The results obtained thus suggest that, except for kidney, the responses in mouse tissues of three SOD isoenzymes (protein levels and mRNA abundance) to swimming training are different and that kidney may be one of the most sensitive organs to adapt to oxidative stress during physical training, although the mechanism remains vague.

Animals↗
PubMed2000

Angiotensin II type 2 receptors stimulate collagen synthesis in cultured vascular smooth muscle cells.

Previously, we and others have shown that angiotensin II enhances vascular smooth muscle cell extracellular matrix synthesis via stimulation of the angiotensin II type 1 (AT(1)) receptor. Recently, expression of the type 2 (AT(2)) receptor has been confirmed in the adult vasculature, but its role has not yet been fully defined. The aim of the present study was to examine the effects of stimulation of AT(2) receptors on collagen synthesis in vascular smooth muscle cells. Retroviral gene transfer was used to supplement adult vascular smooth muscle cells with AT(2) receptors to mimic the vasculature in vivo. The treatment of these cells with the AT(2) receptor agonist CGP42212A (10(-7) mol/L) alone did not cause a significant change in p42/p44 MAP kinase activity but caused a modest (30% to 50%) decrease in protein tyrosine phosphatase activity. Treatment with CGP42112A also caused a dose- and time-dependent increase in both cell-associated and secretory collagen synthesis (148+/-17% of control at 48 hours, P<0.05), which was completely inhibited by the AT(2) receptor antagonist PD123319, unaffected by the AT(1) receptor antagonist losartan, and attenuated by treatment with pertussis toxin or G(alpha)(i) antisense oligonucleotides. Interestingly, studies in other cell lines demonstrated that CGP42112A caused similar results in transfected mesangial cells but had essentially opposite effects in fibroblasts (NIH-3T3-AT(2)). These results suggest that AT(2) receptor stimulation can increase collagen synthesis in vascular smooth muscle cells via a G(alpha)(i)-mediated mechanism and provide evidence for heterogeneity in the effects of AT(2) receptor stimulation in different tissues.

Animals↗
PubMed2000

Acid instillation enhances the inflammatory response to subsequent lipopolysaccharide challenge in rats.

Aspiration of gastric contents is one of leading causes of the acute respiratory distress syndrome (ARDS). The pathogenesis of acid aspiration-induced acute lung injury is well understood. Less clear is why patients who have suffered acid aspiration are susceptible to ARDS. We studied the effects of acid instillation on the inflammatory response to subsequent lipopolysaccharide (LPS) challenge in rats. Instillation of acid into the right lung worsened the pathology induced by LPS that was administered 24 h after acid instillation. This included worsened oxygenation, increased pulmonary edema, increased production of tumor necrosis factor-alpha (TNF-alpha) and cytokine-induced neutrophil chemoattractant, neutrophil accumulation and mobilization to the alveolar spaces, and nitric oxide (NO) production. Of interest, neutrophil mobilization, NO production, and protein permeability were also magnified in the left lung. These effects were attenuated by administration of the protein tyrosine kinase (PTK) inhibitors genistein and tyrphostin AG556. These data suggest that acid instillation primes the rat to enhance the inflammatory response to subsequent endotoxin challenge and that at least part of the augmented inflammatory response depends on PTK.

Animals↗
PubMed2000

Hypercoagulopathy with piperacillin administration in osteomyelitis.

A 51-year-old man with osteomyelitis developed acute renal failure and superior mesenteric venous (SMV) thrombosis after piperacillin (PIPC) treatment. Coagulation profile disclosed disseminated intravascular coagulation (DIC). The serum levels of IgE and eosinophil cationic protein showed significant increases, while a lymphocyte stimulation test with PIPC also demonstrated an extremely high index. These observations suggest that hypersensitivity to PIPC might play a role in the pathogenesis of acute renal failure and SMV thrombosis due to hypercoagulopathy. Withdrawal of PIPC and anticoagulation therapy resulted in clinical improvement and normalization of the affected laboratory data. This is the first report to describe PIPC-induced hypercoagulopathy.

Acute Kidney Injury↗
PubMed2000

Sex-related differences in urinary excretion of egualen sodium in rats.

Egualen sodium (sodium 3-ethyl-7-isopropyl-1-azulenesulfonate 1/3 hydrate) is a new antiulcer drug. There has been no difference observed in absorption between male and female rats, the relative amount of metabolites in male plasma has been higher than that in females, and the excretion ratios of metabolites in males have been significantly higher than those in females. However, the plasma concentration profile of total radioactivity in males has been higher than that in females. To clarify this discrepancy, the renal clearances and plasma concentrations of the unchanged drug and its metabolites were determined. The renal clearance of the unchanged drug in males was 21 times lower than that in females, and the urinary excretions in males and females were 2.1 and 39.5% of dose, respectively. This indicates that the major factor in the sex-related difference observed in the plasma concentration of total radioactivity is due to the difference in the renal clearance of the unchanged drug between the sexes. The results of treatments with probenecid in normal and gonadectomized rats revealed that egualen sodium was mainly excreted into urine by secretion through the renal tubule. Furthermore, the results of treatments with testosterone in rats revealed that the excretion of egualen sodium was highly affected by androgens. These facts indicated that the sex-related difference observed in the plasma concentration of total radioactivity can be attributed to the inhibition of renal tubular secretion of the unchanged drug by androgens. This is the first example of sex-related differences in both metabolism and excretion.

Administration, Oral↗
PubMed2000

[Multiple Aspergillus brain abscesses complicated by bronchial asthma].

A 35-year-old man was hospitalized for the treatment of severe asthma attack. His condition improved with intensive steroid chemotherapy under artificial ventilation. On the 12th hospital day, he was taken off respirator support but lost consciousness afterward. Computed tomography of the brain disclosed multiple hypodense lesions with bleeding. T1-weighted magnetic resonance imaging disclosed low-intensity lesions containing high-intensity areas. T2-weighted images showed heterogeneous high-intensity lesions. The autopsy specimen demonstrated multiple brain abscesses. Histologic examination revealed branching fungal hyphae in abscess walls and also extending through arterial walls with emboli. These findings yielded a diagnosis of multiple Aspergillus infarct abscesses of the brain.

Adult↗
PubMed2000

Thrombopoietin stimulates murine lineage negative, Sca-1+, C-Kit+, CD34- cells: comparative study with stem cell factor or interleukin-3.

It has recently been reported that human thrombopoietin (TPO) acts on early hematopoietic progenitor cells. Consequently, we investigated the effects of TPO on murine hematopoietic progenitor cells using lineage negative (Lin-), Sca-1+, c-Kit+ marrow cells from 5-fluorouracil-treated mice. One hundred enriched cells were cultured in suspension with various single cytokines for 5 days. When cultured with the single cytokines as stem cell factor (SCF), TPO, or interleukin (IL)-3, these cells were maintained or had increased by day 5, whereas only a few cells survived in cultures with granulocyte colony stimulating factor, IL-11, or IL-6. We extended the study in serum-free or serum-containing suspension cultures with SCF or TPO. Anti-TPO antibodies did not inhibit the effects of SCF on enriched cells but did inhibit the effects of TPO on those cells. We further examined the effects of TPO, SCF, and IL-3 on other populations of murine hematopoietic progenitor cells. Either TPO or SCF as a single cytokine could maintain murine Lin-, Sca-1+, c-Kit+, CD34- marrow cells, which are the most dormant cells. In addition, IL-3 increased Lin-, Sca-1-, c-Kit+ cells more than did SCF and TPO but did not stimulate Lin-, Sca-1+, c-Kit+, CD34- cells more. These results indicate that TPO as well as SCF may be key regulators in the proliferation of murine hematopoietic early progenitor cells.

Animals↗
PubMed2000

[The stenoses at the terminal portion of the internal carotid artery improved after initiation of antithyroid therapy: a case report].

We reported the case of a 19-year-old female complicated with Basedow disease. She was admitted, complaining of headache and endocrine function tests showed hyperthyroidism. CT scan revealed left intraventricle hemorrhage and angiography revealed the stenoses at the terminal portion of the bilateral internal carotid arteries (ICA) without basal moyamoya vessels. During the angiography, a thyroid crisis occurred and we initiated the antithyroid therapy. Bilateral CAG a month after the onset revealed that the stenoses had improved partially and the stenosis was thought to be vasospasm caused by the intraventricle hemorrhage. But as the collateral circulation had already been established soon after the hemorrhage, we suspected that the stenoses at the terminal portion of the ICA had existed before the intraventricle hemorrhage. Angiography was performed one year after the onset and bilateral CAG revealed that the stenoses at the terminal portion of the ICA had also improved. As some investigators have mentioned that Basedow disease might be associated with the causal genesis of Moyamoya disease, we suspected that Basedow disease might have played an important role in vasospasm after hemorrhage and that the stenoses at the terminal portion of the ICA might have existed before the hemorrhage took place.

Adult↗
PubMed2000

[Perineural spreading along the trigeminal nerve in a patient with primary intracranial malignant lymphoma: a case report].

We report a rare primary intracranial malignant lymphoma which spread along the trigeminal nerve through the skull base foramen. The patient was a 50-year-old woman, who was diagnosed as having a primary intracranial malignant lymphoma in the right temporal lobe and had undergone an operation and radiation 5 years previously. The tumor was reduced in size and no recurrent tumor could be detected for 5 years. The patient complained of left face swelling and CT scan revealed a large mass in the pterygopalatine fossa. MRI revealed the recurrent tumor in the left Meckel's cave with extension into the cavernous sinus. The tumor extended through the foramen ovale into the pterygopalatine fossa, through the superior orbital fissure into the orbital cavity and through the infraorbital fossa into the face subcutaneously. Biopsy of the subcutaneous tumor was carried out and the pathological diagnosis was malignant lymphoma, B cell type, which was identical with the initial tumor. MRI revealed the enlarged trigeminal nerve and 3D-CT revealed the enlargement of the infraorbital fossa and the foramen ovale. We suspected that primary intracranial malignant lymphoma had recurred in the left Meckel's cave and the tumor had spread along the peripheral three divisions of the trigeminal nerve. Perineural spreading along the trigeminal nerve passing through the skull base in patients with nasopharyngeal carcinoma is not rare, but this rarely occurs in the case of intracranial tumors.

Antineoplastic Combined Chemotherapy Protocols↗