Biomedical subjects

Y Yoshida

Publications and source records attributed to Y Yoshida.

At least 271 records · Page 15Linked to original sources

PubMed2000

[Craniopharyngioma presenting a symptom of pituitary apoplexy and hyponatremia: a case report].

We report a case of a 70-year-old woman admitted to our hospital with sudden headache, drowsiness and hyponatremia. MRI on admission showed an intrasellar mass with suprasellar extension. Serum examination revealed decreased sodium and hypopituitarism, but they were normalized gradually by compensation using hydrocortisone, thyroid hormone and salt. Afterwards, masked diabetes insipidus appeared and required aqueous pitressin for the control of urine volume. A removal operation was performed uneventfully using the transsphenoidal approach and histological examination confirmed squamous-papillary type craniopharyngioma. Intratumoral hemorrhage of the craniopharyngioma is extremely rare. These cases tend to occur after over 15 years of maturation and the squamous-papillary type tend to bleed more than the adamantinomatous type. However, it is very difficult to make a differential diagnosis between craniopharyngioma with intratumoral hemorrhage and pituitary apoplexy, judging only by symptoms or interventional radiology. The definite mechanism of hyponatremia associated with a parasellar lesion is still obscure, but compression to the anterior hypothalamus or pituitary gland by an enlargement of the parasellar tumor is generally hypothesized.

Aged↗

PubMed2000

[The medical thought of Nanmei Kamei].

Nanmei Kamei (1743-1814) was a representative Confucianist and herbal doctor of the Post-Edo age in the Fukuoka han. While in the former half of his life he gained fame with his excellent Chinese poetry in the west part of Japan, in the latter half of his life he also became famous as a teacher of his son "Shoyo" (1773-1836), Tanso Hirose (1782-1856) and others. Until the present, studies of him have centered on these aspects of his work, but they have been insufficient. The purpose of this paper is to clarify the thought of Nanmei's medical science which was taught by Dokusyoan Nagatomi (1732-66) in 1761. In it we can find not only Confucian thought but also European thought. Moreover, he brought forward an eclectic position combining Chinese and European medicine which became "Ichizu ni Yoranu noga Michi," by associating frequently wuth some scholars of Dutch medicine, such as Genshun Koishi (1743-1803), Nankei Tachibana (1732-1805) and Gentaku Otuki (1757-1827). Studying the details of how he came to this thought can be, I think, a way of understanding the whole of his thought completely.

History, 17th Century↗

PubMed2000

Microscopy investigations. Techniques, results, limitations.

This paper critically reviews current microscopy techniques that are used to image resin-dentin interfaces and more in particular to investigate the process of hybridization and resin-tag formation. A short description of the four most commonly used microscopy techniques with their necessary specimen-preparation methodology is provided along with a discussion of their possibilities, limitations and potential artifact formation. With this critical appraisal on microscopy techniques available to study adhesive interfaces, it is hoped to encourage the use of high-resolution analytical tools to further elucidate the mechanisms of bonding at the ultra-structural level. Besides ultra-morphologic characterization, more research should be devoted to study the chemical and physical properties of resin-dentin bonds. The final objective of such fundamental research should be to establish a more durable and reliable adhesive restorative technique.

Artifacts↗

PubMed2000

On-line measurement of intracellular ATP of Saccharomyces cerevisiae and pyruvate during sake mashing.

The concentrations of intracellular ATP of Saccharomyces cerevisiae and pyruvate in a medium were instantaneously increased by pulse addition of glucose during starvation. They were reduced rapidly by alcohol fortification of the medium, accompanied by simultaneous increases of acetaldehyde concentration and inviability of yeast cells. These results were monitored during fermentation of sake mash by an on-line measuring method. Intracellular ATP and pyruvate concentrations were considered to be indicators of the physiological state of the yeast in sake mash. During sake mashing, it was observed that an increase in temperature enhanced the intracellular ATP concentration and the pyruvate production of the yeast. Since pyruvate production was not affected intensely by changes in temperature during cultivation in a glucose-limited chemostat, this effect was thought to be due to the enhanced rates of cell-growth and/or alcohol production. This suggests that the control of mashing temperature during cell growth until about 10% alcohol accumulation is achieved is important for the control of the pyruvate concentration in sake mash.

Journal Article↗

PubMed1999

Genetic analysis of the gene cluster responsible for synthesis of serotype e-specific polysaccharide antigen in Actinobacillus actinomycetemcomitans.

A gene cluster associated with the biosynthesis of the serotype e-specific polysaccharide antigen (SPA) of Actinobacillus actinomycetemcomitans IDH1705 belonging to serotype e was cloned and sequenced. This cluster consisted of 18 open reading frames. Escherichia coli produced the polysaccharide that reacts with the serotype e-specific antiserum when transformed with a plasmid containing the cluster. Comparing the structure of the gene cluster with similar clusters from A. actinomycetemcomitans strains Y4 (serotype b) and NCTC9710 (serotype c) revealed that a 5.3-kb region containing the distal half of one gene and two entire genes in the cluster from strain IDH1705 replaced a 6.2-kb region containing eight genes in the cluster from strain Y4, and a 4.7-kb region containing four genes in the cluster from strain NCTC9710. These results suggest that this region is essential to the antigenic specificity of serotype e A. actinomycetemcomitans.

Aggregatibacter actinomycetemcomitans↗

PubMed1999

Tob2, a novel anti-proliferative Tob/BTG1 family member, associates with a component of the CCR4 transcriptional regulatory complex capable of binding cyclin-dependent kinases.

Human cDNAs encoding a novel member of Tob/BTG1 anti-proliferative family proteins were cloned. The putative protein product termed Tob2 consisted of 344 amino acids with high similarity to the Tob protein. The tob2 mRNA was 4.1 kb long and was ubiquitously expressed in human adult tissues, as was revealed by Northern blot hybridization. However, further in situ hybridization analysis showed a characteristic expression of the tob2 mRNA in oocytes, suggesting a unique role of Tob2 in oogenesis. Like the Tob protein, Tob2 inhibited cell cycle progression from the G0/G1 to S phases. Intriguingly, the amino-terminal half of Tob2 as well as that of Tob was associated with a human homologue of yeast Caf1, a component of the CCR4 transcription factor complex. Moreover, Caf1 was associated with cyclin dependent kinases. These data suggested that both Tob and Tob2 were involved in cell cycle regulation through their interaction with Caf1. Finally, the tob2 gene was mapped to human chromosome 22q13.1-q13.31.

3T3 Cells↗

PubMed1999

Aortic arch reconstruction by transluminally placed endovascular branched stent graft.

BACKGROUND: Recently, thoracic aortic stent grafting has emerged as an alternative therapeutic modality for patients with thoracic aortic aneurysms and aortic dissections. However, its application has been limited to descending thoracic aortic aneurysms distal to the aortic arch. We report our initial clinical experience of endovascular branched stent graft repair for aortic arch aneurysms. METHODS AND RESULTS: Endovascular grafting with Inoue branched stent grafts was attempted for 15 patients with thoracic aortic aneurysms and aortic dissections under local anesthesia (n=14) or general anesthesia (n=1). Single-branched stent grafts were used in 14 patients, and a triple-branched stent graft in one. The branched stent grafts were delivered through a 22F or a 24F sheath under fluoroscopic guidance and implanted across the aneurysmal aortic arch. In 2 patients, the single-branched stent graft did not pass through the 22F sheath used. Complete thrombosis of the aneurysm was ultimately achieved in 11 patients (73%). Of 4 persistent leaks, 1 minor leak spontaneously thrombosed and 1 major leak was successfully treated by additional straight stent graft placement. In 1 patient, the right external iliac artery ruptured during the withdrawal of the sheath and was successfully repaired by the implantation of a straight stent graft. One patient with severe stenosis of the aortic graft section was successfully managed by additional stent deployment. Peripheral microembolization to a toe occurred in 1 patient, and cerebral infarction occurred in 1 other patient. Two patients who had failed to receive endovascular stent grafts died during an average follow-up of 12.6 months, 1 of pneumonia and the other of rupture of a concomitant abdominal aortic aneurysm. CONCLUSIONS: This report demonstrates the technical feasibility of endovascular branched stent graft repair for aneurysms located at the aortic arch. Careful, longer follow-up and further extensive clinical trials are awaited toward establishing this technique as a recommendable alternative to surgical treatment of thoracic aortic aneurysms.

Adult↗

PubMed1999

Synthesis and anti-Helicobacter pylori activity of FR182024, a new cephem derivative.

The synthesis and anti-Helicobacter pylori activity of a novel cephem derivative FR182024 (1) are described. FR182024 having a (5-methyl-1,3,4-thiadiazol-2-yl)-thio moiety at the 3-position and a phenylacetamido at the 7-position was found to have extremely potent in vitro anti-H.pylori activity, superior therapeutic efficacy to AMPC and CAM, and low potential for causing diarrhea.

Amoxicillin↗

PubMed1999

Adenovirus-mediated transfer of p33ING1 with p53 drastically augments apoptosis in gliomas.

The p53 tumor suppressor gene is an important target for the gene therapy of cancers, and clinical trials targeting this gene have been conducted. Some cancers, however, are refractory to p53 gene therapy. Therefore, it has been combined with other therapies, including chemotherapy and radiotherapy, to enhance the cytopathic effect of p53 induction. The p33ING1 gene cooperates with p53 to block cell proliferation. In this study, we investigated whether adenovirus (Adv)-mediated coinduction of p33ING1 and p53 enhances apoptosis in glioma cells (U251 and U-373 MG), which showed no genetic alterations but low expression levels of p33ING1. Although the single infection of Adv for p33ING1 (Adv-p33) at a multiplicity of infection (MOI) of 100, or Adv for p53 controlled by myelin basic protein (MBP) promoter (Adv-MBP-p53), a glioma-specific promoter, at a MOI of 50, did not induce apoptosis in U251 and U-373 MG glioma cells; coinfection of Adv-p33 and Adv-MBP-p53 at the same MOIs induced drastically enhanced apoptosis in both cell lines. Apoptosis was not induced in NGF-treated PC-12 cells infected with a high MOI (300) of Adv-p33 nor in those coinfected with Adv-p33 (100) and Adv-MBP-p53 (50). Coinfection of Adv-p33 and Adv-MBP-p53 demonstrated morphological mitochondrial damage during the initial stage of apoptosis, which likely led to apoptotic cell death. Our results indicate that this coinfection approach can be used as a modality for the gene therapy of gliomas, sparing damage to normal tissues.

Adenoviridae↗

PubMed1999

Phosphorylation/Dephosphorylation steps are crucial for the induction of CYP2B1 and CYP2B2 gene expression by phenobarbital.

The effects of several protein kinase activators and protein phosphatase inhibitors on the phenobarbital (PB)-induced gene expression of CYP2B1 and CYP2B2 (CYP2B1/2B2) in adult rat hepatocytes were investigated. Insulin, epidermal growth factor, interleukin 6, cAMP, phorbol 12-myristate 13-acetate, tumor necrosis factor alpha, vanadate, and okadaic acid were found to suppress the induction of CYP2B1/2B2 at mRNA and protein levels in hepatocytes. cAMP and vanadate completely suppressed the induction of CYP2B1/2B2 gene expression in both rat hepatocytes and liver. The addition of genistein to vanadate-treated hepatocytes partially recovered the induction of CYP2B1/2B1 gene expression by PB. These results of the present study demonstrate that phosphorylation/dephosphorylation steps are crucial for the induction of CYP2B1/2B2 gene expression by PB.

Animals↗

PubMed1999

Relative level of expression of Bax and Bcl-XL determines the cellular fate of apoptosis/necrosis induced by the overexpression of Bax.

The Bax protein plays a critical role in the apoptosis of cancers induced by radiotherapy or chemotherapy, which induce both apoptosis and necrosis. We transduced various glioblastoma cells with the Bax gene via an adenoviral vector and found that A-172 cells led to necrotic cell death, while U251 cells apoptotic cell death, even though a similar level of Bax protein was introduced. A-172 cells displayed a much higher constitutive expression of the Bcl-XL protein compared with that of U251 cells. Upon simultaneous overexpression of the Bcl-XL and Bax proteins in the U251 cells, Bax-induced apoptosis of U251 cells was suppressed and an increase in the number of necrotic cells was seen. Moreover, induction of a higher amount of Bax protein in A-172 cells increased the percentage of apoptotic cells. In conclusion, if a cancerous cell expresses a high enough amount of Bax to undergo death, apoptosis will be induced. If a cancerous cell expresses a level of Bcl-XL which prevents Bax-induced apoptosis, the overexpression of Bax leads to necrotic cell death.

Apoptosis↗

PubMed1999

Three isoforms of mammalian hyaluronan synthases have distinct enzymatic properties.

Three mammalian hyaluronan synthase genes, HAS1, HAS2, and HAS3, have recently been cloned. In this study, we characterized and compared the enzymatic properties of these three HAS proteins. Expression of any of these genes in COS-1 cells or rat 3Y1 fibroblasts yielded de novo formation of a hyaluronan coat. The pericellular coats formed by HAS1 transfectants were significantly smaller than those formed by HAS2 or HAS3 transfectants. Kinetic studies of these enzymes in the membrane fractions isolated from HAS transfectants demonstrated that HAS proteins are distinct from each other in enzyme stability, elongation rate of HA, and apparent K(m) values for the two substrates UDP-GlcNAc and UDP-GlcUA. Analysis of the size distributions of hyaluronan generated in vitro by the recombinant proteins demonstrated that HAS3 synthesized hyaluronan with a molecular mass of 1 x 10(5) to 1 x 10(6) Da, shorter than those synthesized by HAS1 and HAS2 which have molecular masses of 2 x 10(5) to approximately 2 x 10(6) Da. Furthermore, comparisons of hyaluronan secreted into the culture media by stable HAS transfectants showed that HAS1 and HAS3 generated hyaluronan with broad size distributions (molecular masses of 2 x 10(5) to approximately 2 x 10(6) Da), whereas HAS2 generated hyaluronan with a broad but extremely large size (average molecular mass of >2 x 10(6) Da). The occurrence of three HAS isoforms with such distinct enzymatic characteristics may provide the cells with flexibility in the control of hyaluronan biosynthesis and functions.

Animals↗

PubMed1999

Expression level of Bcl-2 determines anti- or proapoptotic function.

Bcl-2 is an oncogene with antiapoptotic function. However, Bcl-2 is converted to a Bax-like death effector by caspases, suggesting that the expression of Bcl-2 may not favor the growth of cancers. We introduced the Bcl-2 gene to gliomas via adenovirus (Adv; Adv-Bcl-2) with the Adv for Fas (Adv-Fas) and the Adv for Fas ligand (Adv-FL) to evaluate the antiapoptotic function of Bcl-2. In U251 glioblastoma cells, Bcl-2 at a low level of expression repressed apoptosis induced by Adv-Fas and Adv-FL, whereas Bcl-2 at a high level of expression did not. On the other hand, Bcl-X(L) showed antiapoptotic function against Fas-mediated apoptosis, irrespective of its expression level. In glioblastoma cells, induction of Bcl-2 alone at a high level induced apoptosis, whereas induction of Bcl-X(L) alone did not. As the multiplicity of infection of Adv-Bcl-2 was increased, the quantity of a cleaved product of Bcl-2 increased. Induction of caspase-inhibitory genes (CrmA and p35) inhibited apoptosis induced by Adv-Bcl-2. Induction of Bcl-2 led to alteration of the membrane potential and structure of the mitochondria. In summary, although Bcl-2 at a low level of expression was antiapoptotic, Bcl-2 at a high level of expression was proapoptotic to Fas-mediated apoptosis. Overexpression of Bcl-X(L) was consistently antiapoptotic to Fas-mediated apoptosis.

Apoptosis↗

PubMed1999

Acquired immunity in nude mice induced by expression of the IL-2 or IL-4 gene in human pancreatic carcinoma cells and anti-tumor effect generated by in vivo gene transfer using retrovirus.

We have examined the anti-tumor effect in nude mice caused by human pancreatic cancer cells (AsPC-1) modified to secrete IL-2 or IL-4. Loss of tumorigenicity of cytokine-producing, but not wild-type, cells was observed despite their unaltered in vitro proliferation rates; and these anti-tumor effects were dependent on the amount of cytokine released. Wild-type cells inoculated into mice which had rejected IL-2- or IL-4-producer cells showed significant growth retardation, while no retardation was detected when unrelated human colon carcinoma cells were inoculated. Histological examination of regressing IL-2- or IL-4-producing AsPC-1 tumors in nude mice revealed infiltration by CD11b-, but not CD90-, positive cells around the tumors. Treatment of nude mice with anti-asialoGM(1) antibody did not affect loss of tumorigenicity. Mice injected i.p. with IL-2- or IL-4-producing AsPC-1 cells did not die, in contrast to mice inoculated with wild-type cells. Injection of retrovirus-bearing IL-2, but not beta-galactosidase, gene into mice which had wild-type cells in the peritoneal cavity also significantly prolonged survival. Thus, expression of the IL-2 or IL-4 gene in AsPC-1 cells may generate tumor-specific acquired immunity, even in mature T cell-deficient conditions. An anti-tumor response can be induced by in vivo transfer of the IL-2 gene.

Animals↗

PubMed1999

Highly augmented cytopathic effect of a fiber-mutant E1B-defective adenovirus for gene therapy of gliomas.

An E1B 55-kDa gene-defective adenovirus (Adv), ONYX-015, has been reported to be a highly useful replication-competent Adv that shows cytopathic effect for cancers with an abnormal p53 gene, without damaging normal tissues. In this study, we combined this Adv (Adv-E1AdB) with a fiber mutation, F/K20, which has a stretch of 20 lysine residues added at the COOH-terminus of the fiber and shows high transduction efficiency to gliomas. In U-373 MG glioma cells, the transduction efficiency of Adv-F/ K20 for lacZ was nine times higher than that of the Adv with wild-type fiber (Adv-F/wt) for lacZ. At a multiplicity of infection of 30, the replication efficiency of Adv-E1AdB-F/K20 was 11 times higher than that of Adv-E1AdB with wt fiber (Adv-E1AdB-F/wt). The ED50 value of AdvE1AdB-F/K20 to U-373 MG cells, which is a measure of the in vitro cytopathic effect, was 32 times greater than that of Adv-E1AdB-F/wt. injection of Adv-E1AdB-F/K20 suppressed the in vivo growth of tumors. The antitumoral effect of Adv-E1AdB-F/K20 was remarkably stronger than that of Adv-E1AdB-F/wt. A greater quantity of replicated virus protein (hexon) by infection with Adv-E1AdB-F/K20 was demonstrated in vitro and in vivo, compared with that of Adv-E1AdB-F/wt. In conclusion, gene therapy using Adv-E1AdB-F/K20, which drastically augmented the antitumoral effect of Adv-E1AdB, will be a promising therapeutic approach for gliomas.

Adenovirus E1B Proteins↗

PubMed1999

Activation of ascending antinociceptive system by vagal afferent input as revealed in the nucleus ventralis posteromedialis.

Thalamic nociceptive neurons receiving afferent input from the tooth pulp (TP) were recorded from the nucleus ventralis posteromedialis proper (VPM) in cats anesthetized with urethane and chloralose. Effects of cervical vagus nerve stimulation on responses of TP neurons in the VPM were investigated. Twenty-one tooth pulp specific (TPS) and eight wide dynamic range (WDR) neurons with TP input were obtained from the periphery (shell region) of the posterior half of the VPM. Of these, many were also excited by electrical stimulation of trigeminothalamic tract (TTT) fibers in the trigeminal medial lemniscus. A conditioning-test paradigm was used to examine effects of vagal stimulation on responses of VPM neurons to electrical stimulation of TP and TTT. Inhibition of the responses was observed in 12 TPS and seven WDR neurons. Local anesthetic block of the mesencephalic periaqueductal gray (PAG) and/or nucleus raphe dorsalis (NRD) eliminated the inhibitory effects of vagal stimulation on the responses of both classes of TP neurons to TTT stimulation. In contrast, the inhibitory effects on responses to TP stimulation were insignificantly affected. These data suggest that vagal afferents can activate the ascending antinociceptive pathway from PAG/NRD onto VPM, in addition to activating the descending antinociceptive system acting upon the lower brain stem.

Afferent Pathways↗

PubMed1999

A novel NDP-6-deoxyhexosyl-4-ulose reductase in the pathway for the synthesis of thymidine diphosphate-D-fucose.

The serotype-specific polysaccharide antigen of Actinobacillus actinomycetemcomitans Y4 (serotype b) consists of D-fucose and L-rhamnose. Thymidine diphosphate (dTDP)-D-fucose is the activated nucleotide sugar form of D-fucose, which has been identified as a constituent of structural polysaccharides in only a few bacteria. In this paper, we show that three dTDP-D-fucose synthetic enzymes are encoded by genes in the gene cluster responsible for the synthesis of serotype b-specific polysaccharide in A. actinomycetemcomitans. The first and second steps of the dTDP-D-fucose synthetic pathway are catalyzed by D-glucose-1-phosphate thymidylyltransferase and dTDP-D-glucose 4,6-dehydratase, which are encoded by rmlA and rmlB in the gene cluster, respectively. These two reactions are common to the well studied dTDP-L-rhamnose synthetic pathway. However, the enzyme catalyzing the last step of the dTDP-D-fucose synthetic pathway has never been reported. We identified the fcd gene encoding a dTDP-4-keto-6-deoxy-D-glucose reductase. After purifying the three enzymes, their enzymatic activities were analyzed by reversed-phase high performance liquid chromatography. In addition, nuclear magnetic resonance analysis and gas-liquid chromatography analysis proved that the fcd gene product converts dTDP-4-keto-6-deoxy-D-glucose to dTDP-D-fucose. Moreover, kinetic analysis of the enzyme indicated that the Km values for dTDP-4-keto-6-deoxy-D-glucose and NADPH are 97.3 and 28.7 microM, respectively, and that the enzyme follows the sequential mechanism. This paper is the first report on the dTDP-D-fucose synthetic pathway and dTDP-4-keto-6-deoxy-D-glucose reductase.

Aggregatibacter actinomycetemcomitans↗

PubMed1999

Stromelysin promoter 5A/6A polymorphism is associated with acute myocardial infarction.

BACKGROUND: Rupture of the fibrous cap of an atherosclerotic plaque is a key event that predisposes to acute myocardial infarction (AMI). Matrix metalloproteinases (MMPs) may contribute to weakening of the cap, which favors rupture. Stromelysin, a member of MMP family, is identified extensively in human coronary atherosclerotic lesions. It can degrade most of the constituents of extracellular matrix as well as activating other MMPs, which suggests that it may play an important role in plaque rupture. Recently, a common variant (5A/6A) in the promoter of the stromelysin gene has been identified. The 5A/6A polymorphism could regulate the transcription of the stromelysin gene in an allele-specific manner. METHODS AND RESULTS: To investigate the relation between the 5A/6A polymorphism in the promoter of the stromelysin gene and AMI, we conducted a case-control study of 330 AMI patients and 330 control subjects. The prevalence of the 5A/6A+5A/5A genotype was significantly more frequent in the patients with AMI than in control subjects (48.8% vs 32.7%, P<0.0001). In logistic regression models, the odds ratio of the 5A/6A+5A/5A was 2.25 (95% CI, 1.51 to 3.35). The association of 5A/6A polymorphism with AMI was statistically significant and independent of other risk factors. CONCLUSIONS: The 5A/6A polymorphism in the promoter of the stromelysin gene is a novel pathogenetic risk factor for AMI.

Alleles↗