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Biomedical subjects

Y Nishimura

Publications and source records attributed to Y Nishimura.

At least 217 records · Page 12Linked to original sources

The intra-aortic cannula pump: A novel assist device for the acutely failing heart.

OBJECTIVE: The intra-aortic cannula pump is a catheter pump designed to support the acutely failing heart. It expels blood from the left ventricle into the ascending aorta in a pulsatile flow pattern. The aim of the study was to analyze the hemodynamic performance of this new intracardiac support system in acute heart failure. METHODS: A 24F cannula was studied in a series of 16 sheep. Hemodynamic changes were assessed in the nonfailing, the moderately failing, and the severely failing heart. Heart failure was induced by an injection of microspheres into the left anterior descending coronary artery. The cannula was inserted through the aortic arch and introduced through the aortic valve into the left ventricle. RESULTS: Cannula insertion was feasible in all animals. Flow through the intra-aortic cannula flow was increased to a maximum of 3 L/min. No hemodynamic changes were observed in the nonfailing heart. A significant increase in cardiac output was observed in the moderately and severely reduced left ventricle (2.67 +/- 0.7 L to 3.51 +/- 0.83 L; P =.001; and 1.18 +/- 0.77 L to 2.43 +/- 0.44 L; P =.001, respectively). A drop in left atrial pressure was achieved in moderate and severe heart failure (14.1 +/- 5.93 mm Hg to 9.71 +/- 2.63 mm Hg; P =.0001; and 23 +/- 7.16 mm Hg to 11.2 +/- 2.55 mm Hg; P = 0.0001, respectively). Systolic and diastolic systemic blood pressures increased in the severely failing heart (57.3 +/- 12.8 mm Hg to 75.4 +/- 11.2 mm Hg; P =.0001; and 35.6 +/- 8.2 mm Hg to 60 +/- 14.3 mm Hg; P =.0006, respectively). CONCLUSIONS: Hemodynamic data demonstrate the beneficial effects of the intra-aortic cannula pump in moderate and severe heart failure. The intra-aortic cannula pump represents a new modality for the treatment of acute heart failure.

Animals↗

Wernicke's encephalopathy associated with hemodialysis: report of two cases and review of the literature.

Two rare cases of Wernicke's encephalopathy (WE) in non-alcoholic patients on hemodialysis (HD) are reported. They presented with the clinical triad of WE (ophthalmoplegia, ataxia and disturbance of consciousness) and intravenous administration of thiamine led to complete elimination of these manifestations. Reduced plasma thiamine levels prior to the administration confirmed the diagnosis of WE. Interestingly, a reduction in plasma thiamine levels by about half was seen in one of the patients on HD, suggesting that thiamine, a water-soluble vitamin, can be depleted with HD. In the literature, nine HD-dependent patients have been reported to develop WE, seven of whom were diagnosed postmortem. Their premortem diagnoses included uremic encephalopathy, dysequilibrium syndrome and dialysis dementia, which can often complicate HD and present symptoms similar to those of WE. We therefore emphasize that WE, even though a rare complication, should be suspected in all patients on HD who present with at least one of the clinical triad of WE.

Aged↗

Long-term observation on the changes of somatotopy in the facial nucleus after nerve suture in the cat: morphological studies using retrograde labeling.

To examine the time course of plasticity of the cranial nucleus during axonal regeneration, we followed the topographical reorganization of the cat facial nucleus (FN) up to 24 months after facio-facial nerve suture using retrograde labeling methods. The trunk of the temporal-zygomatico-orbital and both superior and inferior buccolabial branches (defined as main branch) of the facial nerve was cut and sutured again under ketamine hydrochloride anesthesia. At 11-722 days after nerve suture, Fast Blue (FB) and 1,1'-dioctadecyl-3, 3, 3', 3'-tetramethylindocarbocyanine perchlorate (Dil) or horseradish peroxidase (HRP) were injected into the distal part of the sutured main branch and the unoperated posterior auricular branch, respectively. Until about 3 months after suture, the topographical pattern in FN was similar to that observed in normal cats. At about 4 months after suture, FB-labeled motoneurons were distributed not only in the lateral part (including intermediate, dorsal and ventrolateral divisions) but also in the medial subdivision of FN. After a survival period of 18-24 months, FB-labeled neurons were found all over the FN, and their number increased significantly. Interestingly, in the longer survival cases, we noticed that the Dil- or HRP-labeled posterior auricular branch motoneurons also showed a tendency to distribute outside the medial region. The present study showed that somatotopic disorganization starts at around 4 months after suture, which seems to be somewhat slower than that in rats, and continues until a much later postoperative period. Furthermore, we suggested a possibility that the regeneration of one branch may affect the somatotopy of the unoperated nerve branch. These phenomena may contribute to aberrant facial nerve functions such as abnormal associated movement and facial spasm observed after nerve injury.

Amidines↗

High prevalence of Borna disease virus in domestic cats with neurological disorders in Japan.

A total of 15 (T-1-T-15) domestic cats with neurological disorders in Tokyo area were examined for association with Borna disease virus (BDV). None had detectable antibodies to feline immunodeficiency virus (FIV), feline leukemia virus, feline infectious peritonitis virus and Toxoplasma gondii, and only cat T-8 had detectable antibody to FIV. Serological and molecular epidemiological studies revealed a significantly high prevalence of BDV infection in these cats: antibodies against BDV p24 and/or p40 proteins in 10/15 (66.7%) and p24 and/or p40 RNA in peripheral blood mononuclear cells in 8/15 (53.3%). Further, in situ hybridization and immunohistochemistry analyses of the autopsied brain samples derived from one of the cats (T-15) revealed BDV RNA predominantly in neuronal cells in restricted regions, such as olfactory bulb and medulla of cerebrum. Thus, BDV is present in Japanese domestic cats with neurological disorders at a high prevalence.

Animals↗

MR fluid-attenuated inversion recovery imaging as routine brain T2-weighted imaging.

We tried to investigate if magnetic resonance (MR) fluid-attenuated inversion recovery (FLAIR) imaging can be used as a routine brain screening examination instead of spin-echo T2-weighted imaging. Three hundred and ninety-four patients with clinically suspected brain diseases were randomly selected and examined with both brain MR FLAIR and T2-weighted imaging on the axial plane. These two imaging techniques were evaluated by two neuroradiologists as to which imaging was better for routine brain T2-weighted imaging. In 123 of 394 cases (31%), FLAIR imaging was superior to spin-echo T2-weighted imaging. Especially in cases with inflammatory diseases, traumatic diseases and demyelinating diseases, FLAIR imaging was particularly useful. Small lesions bordering cerebrospinal fluid (CSF) are often detected only by FLAIR imaging. In 259 cases (66%), including 147 normal cases (37%), they were equally evaluated. Only in 12 cases (3%) was conventional T2-weighted imaging superior to FLAIR imaging. Cerebrovascular lesions like cerebral aneurysm and Moyamoya disease could not be detected on FLAIR images because these structures were obscured by a low signal from the CSF. Also, because old infarctions tend to appear as low signal intensity on FLAIR images, the condition was sometimes hard to detect. Finally, FLAIR imaging could be used as routine brain T2-weighted imaging instead of conventional spin-echo T2-weighted imaging if these vascular lesions were watched.

Adolescent↗

A randomised dose-comparison trial of granisetron in preventing emesis in children with leukaemia receiving emetogenic chemotherapy.

This randomised study was performed to assess the anti-emetic efficacy and tolerability of two-dose regimens of granisetron in children with leukaemia. 49 children with leukaemia were treated with three consecutive courses of high-dose methotrexate or cytarabine regimen. During the first course, patients were evaluated regarding the emetogenicity of each regimen. They were randomised in a crossover manner to receive 20 or 40 micrograms/kg of granisetron before the second and third course of chemotherapy. Neither emesis nor severe appetite loss were observed in over 80% of patients within the first 24 h in all treatment groups. There was no significant difference in the anti-emetic efficacy between the two-dose regimens of granisetron. However, complete protection was achieved less frequently on days 2 and 3. Older children and girls appeared to be less well protected. No adverse events attributable to granisetron were observed. Granisetron dose regimens of 20 and 40 micrograms/kg are, comparably, well tolerated and effective in controlling chemotherapy-induced emesis in the first 24 h, though this protection fails thereafter, particularly in older patients and girls.

Adolescent↗

Role of Bcl-2 family proteins (Bax, Bcl-2 and Bcl-X) on cellular susceptibility to radiation in pancreatic cancer cells.

The aim of this study was to examine Bax, Bcl-2 and Bcl-XL proteins in human pancreatic cancer cell lines and to clarify the mechanism of radiation resistance. PANC-1 and AsPC-1 pancreatic cell lines were used, both having mutated p53. Radioresistant PANC-1/Rad cells and AsPC-1/Rad cells were obtained by repeated 5 Gy irradiation of PANC-1 cells and AsPC-1 cells, respectively. Radiation was found to inhibit the growth of PANC-1 cells and AsPC-1 cells. After exposure to radiation, detached cells were subjected to FITC-TUNEL staining to calcualte the ratio of apoptosis. TUNEL positive ratios increased dose-dependently in both cell lines. Western blotting showed that the basal level of the Bax/Bcl-2 ratio reflected the radiosensitivity of these cell lines, and Bax expression was obviously upregulated after irradiation in the presence of mutated p53, but Bcl-2 expression remained almost constant. Both PANC-1/Rad and AsPC-1/Rad cells had greater Bcl-XL expression than the parental cells, and the basal level of the Bax/Bcl-2 ratio was no longer predictive of radiosensitivity. Upregulated expression of Bax protein after irradiation was not related to induction of apoptosis in these cells, suggesting that overexpression of Bcl-XL and functional reconstruction of Bcl-2 family proteins are important factors in acquired radioresistance.

Blotting, Western↗

A facile synthesis of D-glucose-type gem-diamine 1-N-iminosugars: a new family of glucosidase inhibitors.

gem-Diamine 1-N iminosugars of D-glucose-type, a new type of glycosidase inhibitors, have been synthesized from siastatin B, isolated from Streptomyces culture. 2-Trifluoroacetamido-1-N-iminosugar, (2S,3R,4R,5R)-2-trifluoroacetamido-5-hydroxymethylpiperidine -3,4-diol was proved to be a potent inhibitor for alpha-D- and beta-D-glucosidases (IC50 1.9x10(-7) and 4.2x10(-7) M, respectively). 2-Acetamido-1-N-iminosugar, (2S,3R,4R,5R)-2-acetamido-5-hydroxymethylpiperidine-3,4-diol also affected these enzymes (IC50 2.9x10(-6) and 5.4x10(-6) M, respectively).

Aspergillus niger↗

A novel microbial infection-responsive drug release system.

The aim of this study was to construct a novel drug delivery system suitable for controlled release of antibiotics. There is a need for devices that release antibiotics only during microbial infection, because prophylactic or prolonged use of antibiotics leads to serious problems, such as renal and liver toxicity and the emergence of drug-resistant bacteria (e.g., meticillin-resistant Staphylococcusaureus). We found previously that Staphylococcus aureus-infected wound fluid showed high thrombin-like activity; therefore, in this study we designed an antibiotic release system triggered by thrombin activity. We synthesized an insoluble polymer-drug conjugate in which gentamicin was bound to poly(vinyl alcohol) hydrogel through a newly developed thrombin-sensitive peptide linker. The conjugate released gentamicin when it was incubated with Staphylococcus aureus-infected wound fluid, with thrombin and leucine aminopeptidase, or with human plasma and Ca2+, whereas no biologically active gentamicin was released when the conjugate was incubated with noninfected wound fluid, with leucine aminopeptidase alone, with thrombin alone, or with plasma. Furthermore, the conjugate reduced the bacterial number in an animal model of Staphylococcus aureus infection. These results demonstrated that the conjugate has sufficient specificity and excellent potential as a stimulus-responsive, controlled drug release system.

Animals↗

Mitochondrial dysfunction in the pathogenesis of necrotic and apoptotic cell death.

Mitochondria are frequently the target of injury after stresses leading to necrotic and apoptotic cell death. Inhibition of oxidative phosphorylation progresses to uncoupling when opening of a high conductance permeability transition (PT) pore in the mitochondrial inner membrane abruptly increases the permeability of the mitochondrial inner membrane to solutes of molecular mass up to 1500 Da. Cyclosporin A (CsA) blocks this mitochondrial permeability transition (MPT) and prevents necrotic cell death from oxidative stress, Ca2+ ionophore toxicity, Reye-related drug toxicity, pH-dependent ischemia/reperfusion injury, and other models of cell injury. Confocal fluorescence microscopy directly visualizes onset of the MPT from the movement of green-fluorescing calcein into mitochondria and the simultaneous release from mitochondria of red-fluorescing tetramethylrhodamine methylester, a membrane potential-indicating fluorophore. In oxidative stress to hepatocytes induced by tert-butylhydroperoxide, NAD(P)H oxidation, increased mitochondrial Ca2+, and mitochondrial generation of reactive oxygen species precede and contribute to onset of the MPT. Confocal microscopy also shows directly that the MPT is a critical event in apoptosis of hepatocytes induced by tumor necrosis factor-alpha. Progression to necrotic and apoptotic cell killing depends, at least in part, on the effect the MPT has on cellular ATP levels. If ATP levels fall profoundly, necrotic killing ensues. If ATP levels are at least partially maintained, apoptosis follows the MPT. Cellular features of both apoptosis and necrosis frequently occur together after death signals and toxic stresses. A new term, necrapoptosis, describes such death processes that begin with a common stress or death signal, progress by shared pathways, but culminate in either cell lysis (necrosis) or programmed cellular resorption (apoptosis) depending on modifying factors such as ATP.

Animals↗

Molecular cloning and sequence analysis of the phosphoprotein (P) gene of the lapinized rinderpest virus.

We determined the nucleotide sequence of the coding region for the phosphoprotein (P) gene of the L strain of rinderpest virus (RPV). The gene encodes two overlapping open reading frames of 1521 and 531 nucleotides. Use of the first ATG would produce a P polypeptide of 507 amino acids, while use of the second ATG would produce a C polypeptide of 177 amino acids. In addition, the insertion of an extra G residue at the editing site generates an alternative mRNA potentially encoding the V protein of RPV. Homology comparisons of the P, C and V proteins among various viruses suggest that RPV is closer to measles virus (MV) than to canine distemper virus (CDV). Alignment of the sequences unique to the V protein revealed that the cysteine residues are well conserved among RPV, MV and CDV, and form a "zinc finger"-like motif.

Amino Acid Sequence↗

Evolution of phosphagen kinase VII. Isolation of glycocyamine kinase from the polychaete Neanthes diversicolor and the cDNA-derived amino acid sequences of alpha and beta chains.

Glycocyamine kinase (GK) was isolated from the marine polychaete Neanthes diversicolor by gel filtration, DEAE-cellulose chromatography, butyl-Toyopearl hydrophobic chromatography, and chromatofocusing. The GK was eluted as a single peak on the latter three chromatographies, and the molecular mass for the native GK was estimated to be about 80 kDa. The SDS-PAGE showed that the isolated GK consists of two distinct subunits in equal proportion, alpha and beta chains, with molecular masses of 42.2 and 43.8 kDa, respectively. The present results suggest that the Neanthes GK has a heterodimeric structure. The cDNAs for alpha and beta chains of Neanthes GK were amplified by PCR and their cDNA-derived amino acid sequences were determined. The alpha and beta chains are composed of 374 and 390 amino acids, and the molecular masses were calculated to be 42,392 and 43,966 Da, respectively, in good agreement with the apparent masses on SDS PAGE. The beta chain has a characteristic N-terminal extension of 15 amino acids, and all of the sequence differences between alpha and beta chains were restricted in the N-terminal region of 50 residues. The overall sequence identity was 92%. The occurrence of heterodimeric nature in Neanthes GK is of great interest from the evolutionary point of view, because the heterodimeric structure is only known for creatine kinase MB-isozyme specific for mammalian heart muscle among phosphagen kinases.

Amino Acid Sequence↗

Augmentation of immune response by altered peptide ligands of the antigenic peptide in a human CD4+ T-cell clone reacting to TEL/AML1 fusion protein.

The 12;21 chromosomal translocation occurs in leukemic cells from 20(30% of patients with B-lineage childhood acute lymphoblastic leukemia, the result being the TEL/AML1 fusion gene carrying a sequence different from TEL or AML1. Because the protein newly formed by TEL/ AML1 fusion is probably not tolerated by human immune system, the fusion region is a good candidate for tumor antigen expressed only in TEL/ AML1-positive leukemic cells. We established two human CD4+ alphabeta T-cell clones (T31.1 and Y41.2) reacting to the TEL/AML1 fusion region, from two unrelated healthy donors. In order to do this, we stimulated peripheral blood mononuclear cells with synthetic peptides corresponding to the TEL/ AML1 fusion region. Both T31.1 and Y41.2 proliferated in response to TEL/ AML1 fusion protein as well as to a peptide IGRIAECILGMNPSR, in the context of HLA-DP5 and DP17, respectively, and killed B lymphoblastoid cells pulsed with the peptide. Furthermore, these T-cell clones proliferated in response to several altered peptide ligands carrying a single residue substitution in the TEL/AML1 peptide, and some induced augmentation of proliferation and production of Th1-type cytokines. These superagonistic altered peptide ligands can be given consideration for anti-leukemic immunotherapy.

Adjuvants, Immunologic↗

Phospholipase A2 augments contraction and intracellular calcium mobilization through thromboxane A2 in bovine tracheal smooth muscle.

Phospholipase A2 (PLA2) induces hyper-sensitivity to muscarinic agonists in airway smooth muscle in vitro. The precise mechanism of this is unknown, but might involve altered calcium homeostasis. In order to elucidate the effects of PLA2, on bovine tracheal smooth muscle contraction, isometric tension and intracellular calcium concentration ([Ca2+]i) were simultaneously measured in fura 2-loaded muscle strips. A high concentration of PLA2 (0.5 microg x mL(-1)) caused the muscle strips to contract, and this contractile response was significantly attenuated by pretreatment with indomethacin (IND; 10 microM), but not by nordihydroguaiaretic acid (NDGA; 10 microM). A low concentration of PLA2 (0.02 microg x mL(-1)) did not directly contract muscle strips. However a low concentration PLA2 significantly enhanced the threshold of the contractile response and that of the [Ca2+]i response to acetylcholine (ACh), but not that of the response to a high K+ concentration. These augmented responses to ACh returned to control levels after pretreatment with IND, a thromboxane (TX) synthetase inhibitor (OKY-046; 10 microM) or a TXA2 receptor antagonist (ONO-3708; 10 microM), but not after NDGA pretreatment. These results suggest that a low concentration of phospholipase A2 enhances smooth muscle responsiveness to acetylcholine by agonist-mediated Ca2+ mobilization facilitated by thromboxane A2. It is concluded that phospholipase A2 plays an important role in bronchial hypersensitivity involving thromboxane A2. It remains to be examined whether similar abnormalities in calcium homeostasis and muscarinic receptor function or coupling are involved in the pathogenesis of asthma.

Airway Resistance↗

Prognostic values of proliferating cell nuclear antigen (PCNA) and Ki-67 for radiotherapy of oesophageal squamous cell carcinomas.

The relationship of immunohistochemical indices of proliferating cell nuclear antigen (PCNA) and Ki-67 to local control and survival rates for patients with oesophageal squamous cell carcinomas treated by definitive radiotherapy (RT) was investigated. Biopsy materials before RT were obtained from 65 patients with oesophageal cancer. The median PCNA labelling index (LI) and the median Ki-67 LI were 52% and 45% respectively. The PCNA LI was independent of known prognostic factors on local control for oesophageal cancer, although Ki-67 LI correlated with several prognostic factors. In the univariate analysis, patients with the PCNA LI of < 52% or the Ki-67 LI of < 45% showed significantly higher local recurrence rates than those with higher LIs (both P < 0.05). This difference in local control rate according to LIs was prominent for the patients treated with conventional fractionation. In the multivariate analysis, T-stage (P = 0.0056) and PCNA LI (P = 0.0332) were significant factors for local control in the final model using a stepwise regression procedure. In conclusion, PCNA LI and Ki-67 LI were significantly correlated with local control probabilities in oesophageal squamous cell carcinomas treated by definitive RT.

Aged↗

Internal tandem duplication of the FLT3 gene and clinical evaluation in childhood acute myeloid leukemia. The Children's Cancer and Leukemia Study Group, Japan.

We analyzed tandem duplication in the juxtamembrane (JM) domain of the FLT3 (FMS-like tyrosine kinase 3/FLK2, CD135) gene in 94 children with acute myeloid leukemia (AML) and evaluated its correlation with clinical features. Longer polymerase chain reaction (PCR) products were observed in five patients; 1/3 of M0, 119 of M1, 1/39 of M2, 1/9 of M3 and 1/12 of M5. The sequence analyses of abnormal PCR products showed that all the abnormal products were derived from tandem duplications involving the JM domain and that all the lengthened sequences were in-frame as we previously reported. Statistical analyses revealed a significantly lower incidence of the tandem duplication in childhood AML patients than in adult patients (P < 0.05), and significantly shorter disease-free survival in patients with mutant FLT3 than in patients with wild-type FLT3 (P < 0.05). Our results suggest that the tandem duplication in the JM domain of the FLT3 gene is not a frequent phenomenon but might be a factor of poor prognosis in childhood patients with AML.

Acute Disease↗