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Biomedical subjects

A Yamada

Publications and source records attributed to A Yamada.

At least 19 recordsLinked to original sources
PubMed2007

Manipulation of cell-sized phospholipid-coated microdroplets and their use as biochemical microreactors.

Cell-sized water droplets coated by a phospholipid layer mimicking the inner surface of living cells were manipulated by laser tweezers and used as biochemical microreactors. The cell-sized phospholipid-coated microdroplets (CPMDs) consisted of a water droplet in mineral oil with a diameter of 1-100 microm and coated by 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine. We monitored the time development of biochemical reactions in a single CPMD obtained after the controlled fusion of two CPMDs containing a substrate and an enzyme, respectively. We present results on two enzymatic reactions: calcein production in the presence of esterase and green fluorescence protein expression.

Biochemistry↗
PubMed2007

Expression of APOBEC3G in kidney cells.

The apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3G (APOBEC3G), a member of the APOBEC family possessing DNA mutator activity through cytosine deamination, is reported to play an important role in host defense against infections such as those of hepatitis B virus and human immunodeficiency virus. Here, we examined the expression of APOBEC3G in human kidney cells to better understand its biological role against infection. APOBEC3G was immunohistochemically detectable in kidney mesangial cells and also to some extent in kidney epithelial tubular cells. In addition, overexpression of APOBEC3G was shown in renal carcinoma tissues and cell lines. APOBEC3G expression was upregulated by inflammatory cytokines, such as interferon, interleukin-6, and tumor necrosis factor. These results may provide new insight into the role of APOBEC3G in host defense against viral infection and cancer.

APOBEC-3G Deaminase↗
PubMed2006

Requirement of nectin, but not cadherin, for formation of claudin-based tight junctions in annexin II-knockdown MDCK cells.

Adherens junctions (AJs) and tight junctions (TJs) comprise a junctional complex which plays key roles not only in cell adhesion and polarization but also in regulation of cell movement and proliferation in epithelial cells. E-Cadherin and nectin are major cell-cell adhesion molecules (CAMs) at AJs, whereas claudin is a major CAM at TJs. We have shown that the cadherin-based cell-cell adhesion is not formed in MDCK cells in which annexin II, a Ca(2+)- and phospholipid-binding protein, is knocked down. Here, we found that TJs and the nectin-based cell-cell adhesions were formed in annexin II-knockdown cells. The formation of TJs in annexin II-knockdown MDCK cells required the nectin-based cell-cell adhesion and afadin, a nectin- and actin-filament-binding protein. In addition, it required the activation of Cdc42 and Rac small G proteins and subsequent reorganization of the IQGAP1-dependent actin cytoskeleton which were induced by the nectin-based cell-cell adhesion. These results indicate that the nectin-based cell-cell adhesion and afadin, but not the cadherin-based cell-cell adhesion, are necessary for the formation of TJs and that the signaling by nectin and the subsequent reorganization of the actin cytoskeleton are also necessary for the formation of TJs under certain conditions.

Animals↗
PubMed2006

The effect of dexamethasone on defective nephrin transport caused by ER stress: a potential mechanism for the therapeutic action of glucocorticoids in the acquired glomerular diseases.

The mechanism by which glucocorticoids govern antiproteinuric effect in nephrotic syndrome remains unknown. Present study examined the protective role of dexamethasone (DEX) in the intracellular trafficking of nephrin under endoplasmic reticulum (ER) stress. Human embryonic kidney-293 cell line expressing a full-length human nephrin was cultured in mediums containing 5.5 or 25 mM glucose with or without DEX. The result revealed that glucose starvation evoked a rapid ER stress leading to formation of underglycosylated nephrin that was remained in the ER as a complex with calreticulin/calnexin. DEX rescued this interfered trafficking through binding to its receptor and stimulating the mitochondrial transcripts and adenosine 5' triphosphate (ATP) production, leading to synthesis of fully glycosylated nephrin. These results suggest that ER-stress in podocytes may cause alteration of nephrin N-glycosylation, which may be an underlying factor in the pathomechanism of the proteinuria in nephrotic syndrome. DEX may restore this imbalance by stimulating expression of mitochondrial genes, resulted in the production of ATP that is essential factor for proper folding machinery aided by the ER chaperones.

Adenosine Triphosphate↗
PubMed2005

The Tokyo subway sarin attack--lessons learned.

The sarin gas attack in the Tokyo subway system is reviewed from a clinical toxicology perspective. Based on the lessons learned from this attack, the following areas should be addressed on a global scale. First, an adequate supply of protective equipment is required, including level B protective equipment with a pressure demand breathing apparatus. In addition, a system should be established that enables a possible cause to be determined based on symptoms, physical findings, general laboratory tests, and a simple qualitative analysis for poisonous substances. If an antidote is needed, the system should enable it to be administered to the victims as quickly as possible. Preparation for a large-scale chemical attack by terrorists requires the prior establishment of a detailed decontamination plan that utilizes not only mass decontamination facilities but also public facilities in the area. A system should be established for summarizing, evaluating, and disseminating information on poisonous substances. Finally, a large-scale scientific investigation of the Tokyo sarin attack should be conducted to examine its long-term and subclinical effects and the effects of exposure to asymptomatic low levels of sarin.

Antidotes↗
PubMed2005

Neuroprotective mechanisms of lidocaine against in vitro ischemic insult of the rat hippocampal CA1 pyramidal neurons.

To compare neuroprotective effects of lidocaine and procaine against ischemic insult, intracellular recordings were made from rat hippocampal CA1 pyramidal neurons in slice preparations. Superfusion of the slices with oxygen- and glucose-deprived medium (in vitro ischemia) produced a rapid depolarization 6 min from the onset. When oxygen and glucose were reintroduced, the membrane depolarized further until it reached 0 mV, and thereafter the membrane showed no functional recovery. Pretreatment with lidocaine (10 microM), but not procaine (50 microM), restored the membrane potential after the reintroduction of oxygen and glucose. Lidocaine, compared to procaine, significantly inhibited the reduction in both tissue ATP content and flavoprotein fluorescence during and after in vitro ischemia. Under electron microscopy, only lidocaine well preserved the structure of mitochondria in the CA1 pyramidal cell body. Extracellular recordings revealed that procaine reduced the field postsynaptic potential whereas lidocaine augmented it. Both drugs reduced the presynaptic volley dose-dependently. Neither lidocaine nor procaine significantly affected a rapid rise of the intracellular Ca2+ level produced by in vitro ischemia in the CA1 region. All the results suggest that the neuroprotective lidocaine action is due to the protection of the mitochondria to maintain the tissue ATP content during and after in vitro ischemia.

Adenosine Triphosphate↗
PubMed2005

Importance of early repair of isolated abdominal aortic dissecting aneurysm.

BACKGROUND: Since the available information on isolated abdominal aortic dissecting aneurysm (AADA) is mainly related to case reports or reports of small groups of patients, its natural history remains undetermined and there is no agreement on its optimal management. The purpose of this study is to define the features and pattern of development of this unusual entity as well as to propose criteria for treatment based on our own experience and previously published data. PATIENTS AND METHODS: We retrospectively evaluated the history of 6 patients diagnosed with AADA. The patients were 5 males and 1 female. The mean age was 71 +/- 8 years (range: 61-80 years), and the mean aneurysm diameter was 54 +/- 14 mm (range: 35-70 mm). All of these patients were hypertensive (100%). History of cerebrovascular accident, ischemic heart disease, peripheral arterial disease, or diabetes mellitus was present in 1 patient, respectively. Two patients developed mycotic AADA. RESULTS: Emergency operations had been performed in 3 cases, and scheduled surgical reconstruction in the remaining 3 cases. Operation consisted of aneurysmectomy and graft replacement of the diseased aortic segment in all cases. One patient treated in an emergency setting died subsequently of multisystem organ failure, but the others did well. CONCLUSION: Symptomatic patients or patients at good risk should undergo surgical repair earlier than in the case of abdominal aortic aneurysm without dissection (AAA). Dissection in addition to an AAA will further increase the weakness of the aortic wall and the possibility of aortic rupture will become higher.

Aged↗
PubMed2004

A phase I trial of cytotoxic T-lymphocyte precursor-oriented peptide vaccines for colorectal carcinoma patients.

In most protocols of peptide-based vaccination, no consideration has been paid to whether or not peptide-specific cytotoxic T-lymphocyte (CTL) precursors are pre-existent in cancer patients. Initiation of immune boosting through vaccination is better than that of immune priming to induce prompt and strong immunity. In this study, 10 human histocompatibility leukocyte antigen-A24(+) patients with advanced colorectal carcinomas were treated with up to four peptides that had been positive for pre-vaccination measurement of peptide-specific CTL precursors in the circulation (CTL precursor-oriented peptide vaccine). No severe adverse effect was observed, although local pain and fever of grade I or II were observed. Post-vaccination peripheral blood mononuclear cells (PBMCs) from five patients demonstrated an increased peptide-specific immune response to the peptides. Increased CTL response to cancer cells was detected in post-vaccination PBMCs of five patients. Antipeptide immunoglobulin G became detectable in post-vaccination sera of seven patients. Three patients developed a positive delayed-type hypersensitivity response to at least one of the peptides administrated. One patient was found to have a partial response; another had a stable disease, sustained through 6 months. These results encourage further development of CTL precursor-oriented vaccine for colorectal cancer patients.

Adult↗
PubMed2004

Characterization of Oita virus 296/1972 of Rhabdoviridae isolated from a horseshoe bat bearing characteristics of both lyssavirus and vesiculovirus.

Oita virus 296/1972 was isolated from the blood of a wild horseshoe bat, Rhinolophus cornutus (Temminck) in 1972. We investigated the pathogenicity of this virus in mice in relation to its histological, immunohistochemical and ultrastructural characteristics and the entire sequence of nucleoprotein gene. This virus caused lethal encephalitis in mice through intracerebral route. This susceptibility of mice was until 3 weeks of age. Immunohistochemical analysis using the convalescent sera obtained from survived adult mice after intracerebral inoculation revealed that many neurons were positive in the cytoplasm, besides no cross reactivity with normal and rabies virus-infected mouse brain tissues to this anti-sera. Ultrastructural analysis disclosed many bullet-shaped and enveloped virions in neurons. These morphological characteristics of the virions are consistent of that of viruses in the family Rhabdoviridae. Budding from endoplasmic membrane suggests that this virus has a similarity with lyssaviruses. Molecular analysis of cDNA coding a tentative nucleoprotein sequence revealed homology with those of viruses in the family Rhabdoviridae. Distance matrix analysis of this gene sequence with those of other rhabdoviruses isolated from mammals disclosed the discrete position of this virus in the phylogenic tree of rhabdoviridae infecting mammals and we renamed this virus as Oita rhabdovirus.

Age Factors↗
PubMed2004

Analysis of cellular localization of SART3 tumor antigen by a newly established monoclonal antibody: heterotopic expression of SART3 on the surface of B-lineage leukemic cells.

SART3 has been identified as a tumor antigen recognized by cytotoxic T-lymphocytes. Subcellular localization of SART3 is still controversial, although it has been studied extensively. In this study, we established an anti-SART3 monoclonal antibody (mAb) to analyze the subcellular localization of SART3 in tumor specimens. Immunohistochemical analysis demonstrated that SART3 was preferentially expressed in the nucleus of cancer cells. Flow cytometric analysis indicated that SART3 was not expressed on the cell surface of tumor cells, except for B-lineage cells. SART3 was detected on the cell surface of several B-lineage leukemic cells with different maturation stages, but not on normal peripheral blood B cells. These results suggest that heterotopically expressed SART3 is a tumor-associated antigen rather than a differentiation antigen on B-lineage cells.

Animals↗
PubMed2004

Characterization of the eicosapentaenoic acid biosynthesis gene cluster from Shewanella sp. strain SCRC-2738.

The 38 kb eicosapentaenoic acid (EPA) biosynthesis gene cluster of Shewanella sp. strain SCRC-2738 was cloned into the cosmid vector (pEPA). A 27 kb nucleotide sequence of the XhoI to SpeI region of pEPA showed EPA production (6.3%) in E. coli JM109. Among the nine open reading frames (ORFs) in this sequence, only five (ORFs 2 and 5-8) were essential for EPA production. High levels of production (16%-22%) were found in E. coli JM109 transformed with a multicopy pNEB vector carrying only the five essential ORFs and in that transformed with a pNEB vector that integrated ORFs 3, 5, 6, 7 and 8, and vector pSTV28 that integrated the ORF2 encoding phosphopantetheinyl transferase (PPTase). Thus, production of EPA appears to be regulated by the presence of all the biosynthesis gene products and by the ratio of PPTase to the other gene products. The temperature -EPA production relationship in E. coli strain DH5alpha varied between constructs, suggesting that it is controlled not only by EPA biosynthesis enzymes but also by other factors in vivo. There was a strict upper temperature limit for EPA biosynthesis: no EPA was synthesized at 30 degrees C in E. coli transformants carrying any gene construct for EPA biosynthesis.

Base Sequence↗
PubMed2003

Arachidonic acid metabolites contribute to the irreversible depolarization induced by in vitro ischemia.

Intracellular recordings were made from hippocampal CA1 neurons in rat slice preparations. Superfusion with oxygen- and glucose-deprived medium (in vitro ischemia) produced a rapid depolarization approximately 5 min after the onset of the superfusion. Even when oxygen and glucose were reintroduced immediately after rapid depolarization, the membrane depolarized further (persistent depolarization) and reached 0 mV (irreversible depolarization) after 5 min from the reintroduction. The pretreatment of the slice preparation with a phospholipase A2 (PLA2) inhibitor, para-bromophenacyl bromide, or a cytochrome p-450 inhibitor, 17-octadecynoic acid, significantly restored the membrane to the preexposure potential level after the reintroduction of oxygen and glucose. The administration of 14,15-epoxyeicosatrienoic acid or 20-hydroxyeicosatetraenoic acid did not change the latency of the rapid depolarization and did not allow the membrane potential to recover after the ischemic exposure. In contrast, after pretreatment with cyclooxygenase or lipoxygenase inhibitors, such as indomethacin, resveratrol, Dup-697, nordihydroguaiaretic acid, and 3,4-dihydrophenyl ethanol, a minority of neurons tested showed postischemic recovery from the persistent depolarization. Improved recovery was also seen after treatment with the free radical scavengers, edaravone and alpha-tocopherol. These results suggest that the activation of the arachidonic acid cascade via PLA2 and the free radicals produced by arachidonic acid metabolism contribute to the irreversible depolarization produced by in vitro ischemia.

Action Potentials↗
PubMed2003

IgG reactive to CTL-directed epitopes of self-antigens is either lacking or unbalanced in atopic dermatitis patients.

We previously demonstrated that CTL-directed epitopes derived from non-mutated self-antigens elicit a type-I allergy in the majority of healthy donors (HD) as did the presence of IgE and IgG reactive to these peptides in the sera of the donors. We investigated in this study whether Igs reactive to eight types of CTL-directed peptides were elevated in the sera of 40 patients with atopic dermatitis (AD). Total IgE levels in the sera of AD patients were significantly higher than those of HD, however, no significant differences between the AD patients and the HD were observed in either the serum levels or the positive rates of IgE reactive to seven of the eight peptides. Total IgG levels were not different from each other, however, IgG reactive to the two peptides with no sequence similarity to other species and one peptide that had similarity to DNA helicase II of enterobacteria were not detectable in the sera of the AD patients. Although IgG reactive to the remaining five peptides, which had sequence similarity to other species, were detectable in both the AD patients and the HD, ratios of peptide-specific IgG1/IgG2 were mostly lower in the AD patients than in the HD. These results indicate that IgG reactive to CTL-directed epitopes of self-antigens is either lacking or unbalanced in AD patients. This information may provide new insight into the immune-mechanisms of elevated auto-reactivity of AD patients.

ADP Ribose Transferases↗
PubMed2003

Identification of an amino acid responsible for the CD3 polymorphism in cynomolgus monkeys (Macaca fascicularis).

The FN18 monoclonal antibody (mAb), directed to CD3 molecules, did not react with the lymphocytes of some cynomolgus monkeys (Macaca fascicularis), because of the polymorphism of the CD3epsilon chain. The epitope recognized by the FN18 mAb was successfully expressed on COS7 cells upon transfection of plasmid DNA coding for the CD3epsilon derived from T cells of a FN18 positive cynomolgus monkey. By construction and expression of plasmid DNA encoding the mutant CD3epsilon, the amino acid residue at position 67 was demonstrated to be involved in the formation of an epitope recognizable by the FN18 mAb.

Amino Acid Sequence↗
PubMed2003

Identification of ribosomal proteins S2 and L10a as tumor antigens recognized by HLA-A26-restricted CTL.

Recent identification of cytotoxic T lymphocyte (CTL)-directed peptides binding to the HLA-A2 and -A24 alleles has opened the door to peptide-based cancer immunotherapies. However, subsequent studies have succeeded in identifying no more than a few CTL-directed peptides that bind to alleles other than HLA-A2 and -A24, thus hampering development of immunotherapies directed at other alleles. We have shown in this study that two genes coding for ribosomal proteins (S2 and L10a) encoded tumor antigens recognized by HLA-A26-restricted CTLs. The S2 mRNA was expressed in all of the cancer cells and non-malignant cell lines tested, but was not expressed in normal tissues except for the testis, muscle, and peripheral mononuclear leukocyte cell (PBMC). In contrast, the L10a mRNA was expressed in all of these cancer and non-malignant cell lines, and also normal tissues, although the expression levels in normal tissues were mostly low. One S2-derived peptide and two L10a-derived peptides had the ability to induce HLA-A26-restricted and peptide-specific CTLs reactive to tumor cells in PBMCs of cancer patients, respectively. These ribosomal protein-derived peptides, and particularly the S2-derived peptide, could be suitable for use in peptide-based immunotherapy for HLA-A26+ cancer patients.

Amino Acid Sequence↗
PubMed2003

A polymorphism in the CYP17 gene relates to the risk of recurrent pregnancy loss.

The CYP17 gene encodes the enzyme cytochrome P450c17alpha, which mediates both 17alpha-hydroxylase and 17,20-lyase activity in the steroid biosynthesis pathway. A T-->C polymorphism in the 5' promoter region of CYP17 has been described. To examine the association between recurrent pregnancy loss (RPL) and a polymorphism in CYP17, a case-control study of 117 cases with RPL and 164 controls was conducted. This polymorphism was investigated by PCR/restriction fragment length polymorphism using DNA from peripheral lymphocytes. The T-->C transition in the variant allele (A2) creates a new recognition site for the restriction enzyme MspA1, which permits designation of the wildtype allele (A1) and A2. Women with the A2 allele of CYP17 had an increased risk of RPL [A1/A1 genotype (reference); A1/A2 genotype: odds ratio (OR), 1.68; 95% confidence interval (CI), 0.94-3.01; A2/A2 genotype: OR, 2.37; 95% CI, 1.16-4.83; P trend, 0.016]. Additionally, there was a similar tendency for the increased risk of primary RPL [A1/A1 genotype (reference); A1/A2 genotype: OR, 2.14; 95% CI, 1.14-4.01; A2/A2 genotype: OR, 2.50; 95% CI, 1.16-5.41; P trend, 0.015]. These results suggest that possession of the A2 variant of CYP17 may predispose to an increased risk of RPL with a gene dosage effect.

Abortion, Habitual↗
PubMed2003

Inhibition of arthritis by systemic administration of endostatin in passive murine collagen induced arthritis.

OBJECTIVE: To investigate the arthritis inhibiting effect of endostatin, known to have potent antiangiogenic activity, systemically given to animal models of rheumatoid arthritis (RA). METHODS: Four kinds of monoclonal anti-type II collagen antibody followed by lipopolysaccharide (LPS) three days later were given to 6 week old, female Balb/c mice to induce arthritis. Three groups of mice received 0.2 mg/kg/day, 2 mg/kg/day, and 10 mg/kg/day of endostatin, respectively, whereas a control group received phosphate buffered saline (PBS). Endostatin or PBS was given for 13 days, starting before the development of arthritis. Arthritis was evaluated by arthritis scores and hind paw thicknesses. Mice were killed for histological examination on the 22nd day after the administration of monoclonal anti-type II collagen antibody. RESULTS: Arthritis developed within three days after LPS administration in both the control and endostatin treatment groups. No difference in the development rate of arthritis was noted between the control and endostatin treatment groups. Arthritis scores remained significantly lower in the endostatin 10 mg/kg/day group than in the control group. Hind paw thicknesses also remained significantly smaller in the endostatin 10 mg/kg/day group than in the control group. Histopathological examination showed that synovial thickening and subchondral bone erosion improved more in the endostatin treatment groups than in the control group. CONCLUSION: The systemic administration of endostatin had an arthritis inhibiting effect in RA animal models. Endostatin inhibited, in particular, pannus formation and bone destruction.

Analysis of Variance↗