Search PubMed⌕ Search

Biomedical subjects

M Murakami

Publications and source records attributed to M Murakami.

At least 451 records · Page 25Linked to original sources
PubMed1998

Effect of carboxy-PTIO, a nitric oxide scavenger, on the proliferation of murine hematopoietic progenitor cells in vitro.

We investigated the effect of 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (c-PTIO), a specific nitric oxide scavenger and a stable radical compound, on the proliferation of murine hematopoietic progenitor cells in vitro. The c-PTIO promoted colony formation by erythropoietin and either interleukin-6 (IL-6) or the c-kit ligand/stem cell factor (SCF) in a methylcellulose culture, where the number of colonies increased 2.2-fold and 1.7-fold, respectively. During the addition of c-PTIO to the liquid cultures of murine bone marrow cells containing a combination of IL-6 and SCF, colony-forming cells in vitro (CFC) and the colony-forming unit in the spleen (CFU-S) increased about 1.8-fold and 1.7-fold, respectively, higher than the control culture after 7 day of culture. When c-PTIO was added twice at days 0 and 2 during the culture, 3.6-fold and 1.7-fold increases over the control were observed in the number of CFC and CFU-S. These results suggest the possibility that c-PTIO regulates the proliferation and differentiation of hematopoietic stem/progenitor cells in vitro.

Animals↗
PubMed1998

Double-sector Lorenz plot scattering in an R-R interval analysis of patients with chronic atrial fibrillation: incidence and characteristics of vertices of the double-sector scattering.

Animal experiments have demonstrated that the minimum R-R interval during atrial fibrillation is proportional to the functional refractory period of the atrioventricular node. On Lorenz plots, atrial fibrillation is characterized by sector-shaped scattering; the vertex of the sector (ie, the minimum R-R interval) represents the functional refractory period. According to the atrioventricular nodal dual-pathway theory, it was hypothesized that the dual atrioventricular nodal pathways associated with chronic atrial fibrillation represent two vertices with two sectors. Detection of two-sector Lorenz plot scattering was attempted in 48 patients with chronic atrial fibrillation who underwent 24-hour ambulatory electrocardiography. Lorenz plot scattering was constructed by means of a computer. Two sectors, suggesting dual pathways, were detected in 19 (40%) of the 48 patients. The two vertices, located at 388 +/- 61 ms (mean +/- SD) and 580 +/- 60 ms were considered to represent the functional refractory periods of the fast and slow pathways, respectively. The vertex indicating the fast pathway showed greater circadian variation than that indicating the slow pathway. In one patient with dual-sector Lorenz plot scattering, whose atrial fibrillation spontaneously converted to sinus rhythm, an electrophysiologic study demonstrated dual atrioventricular nodal pathways. Thus, the Lorenz plot analysis identified two sectors, indicating the dual pathways, in approximately 40% of the patients with chronic atrial fibrillation, and the characteristics of the functional refractory periods of both pathways were estimated from the characteristics of the vertices. Although this study did not provide direct evidence of the dual atrioventricular nodal pathways, the analysis of Lorenz plot scattering may be clinically useful for studying the effects of drugs and/or ablation on the ventricular response in patients with atrial fibrillation based on the dual atrioventricular nodal pathway theory.

Aged↗
PubMed1998

Cell-mediated immunological responses in cervical and vaginal cancer patients immunized with a lipidated epitope of human papillomavirus type 16 E7.

Human papillomavirus (HPV) infection has been causally associated with cervical cancer. We tested the effectiveness of an HLA-A*0201-restricted, HPV-16 E7 lipopeptide vaccine in eliciting cellular immune responses in vivo in women with refractory cervical cancer. In a nonrandomized Phase I clinical trial, 12 women expressing the HLA-A2 allele with refractory cervical or vaginal cancer were vaccinated with four E786-93 lipopeptide inoculations at 3-week intervals. HLA-A2 subtyping was also performed, and HPV typing was assessed on tumor specimens. Induction of epitope-specific CD8+ T-lymphocyte (CTL) responses was analyzed using peripheral blood leukapheresis specimens obtained before and after vaccination. CTL specificity was measured by IFN-gamma release assay using HLA-A*0201 matched target cells. Clinical responses were assessed by physical examination and radiographic images. All HLA-A*0201 patients were able to mount a cellular immune response to a control peptide. E786-93-specific CTLs were elicited in 4 of 10 evaluable HLA-A*0201 subjects before vaccination, 5 of 7 evaluable HLA-A*0201 patients after two vaccinations, and 2 of 3 evaluable HLA-A*0201 cultures after all four inoculations. Two of three evaluable patients' CTLs converted from unreactive to reactive after administration of all four inoculations. There were no clinical responses or treatment toxicities. The ability to generate specific cellular immune responses is retained in patients with advanced cervical cancer. Vaccination with a lipidated HPV peptide epitope appears capable of safely augmenting CTL reactivity. Although enhancements of cellular immune responses are needed to achieve therapeutic utility in advanced cervical cancer, this approach might prove useful in treating preinvasive disease.

Adult↗
PubMed1998

[Organ failure during the perioperative period: pathophysiology and strategy].

After the establishment of the theoretical and clinical background of SIRS, the mechanism of organ failure induction during the perioperative period was gradually clarified. The deterioration of the mutual regulation of cytokines after surgical stress is considered to be a major cause of organ failure. Hypercytokinemia is one of the pathophysiological features after surgical stress, and thus a new therapeutic approach ameliorating the impaired cytokine network has been applied instead of direct targeting therapy for impaired organs. Organ failure can be anticipated based on a precise assessment of the severity of SIRS or CARS. For example, to prevent postsurgical hepatic failure it is important to minimize surgical stress by assessing the preoperative liver reserve capacity. Excessive surgical stress coupled with underestimation of liver function may result in primary multiple organ failure (MOF) after hepatic surgery. Secondary MOF after postsurgical infection may implicate the bacterial translocation mechanism. At present, only CHDF is considered to be a promising therapy for hypercytokinemia. Therefore the prophylactic approach cannot be neglected. The monitoring of cytokines such as IL-6 during the perioperative period provides valuable information for the prediction of organ failure.

Cytokines↗
PubMed1998

NMR studies of salivary glands: from energy metabolism to morphology.

Nuclear magnetic resonance (NMR) spectroscopy has been used to study various physiological functions of salivary glands. This short review summarizes results on energy metabolism and acid-base balance (31P and 14N NMR), electrolytes transport (23Na, 39K, 35Cl and 87Rb NMR) and water transport (1H NMR). The latest development of 1H nuclear magnetic resonance imaging (MRI) allows the three-dimensional structure of salivary glands to be observed with ca. 60 microm resolution, and it is also possible to observe circulation, flow, and volume changes during secretion. The combination of NMR and MRI may open up new fields in the study of exocrine secretion.

Acid-Base Equilibrium↗
PubMed1998

Regulation of cell volume and diffusion of intracellular water in salivary acinar cells.

The regulation of acinar cell volume and the properties of intracellular water were investigated in perfused rat mandibular salivary glands by proton nuclear magnetic resonance (NMR) spectroscopy. Using an inversion-recovery pulse sequence, and an extracellular relaxation reagent (10 mM Gd-DTPA) to suppress the proton NMR signal from extracellular water, acinar cell volume (intracellular water content) in unstimulated glands was shown to depend upon Cl- uptake by basolateral Na+-K+-2Cl- cotransport. Muscarinic and beta-adrenoceptor stimulation induced shrinkage and swelling respectively. In pulsed-field-gradient NMR experiments, the diffusion coefficient of intracellular water was found to be more than an order of magnitude smaller than that of extracellular water. Using this intrinsic difference in diffusivity between the two compartments, cell volume regulation was investigated in intact, perfused glands in the absence of relaxation reagents. Using both NMR techniques, acinar cells in perfused glands were observed to behave like simple osmometers in response to anisosmotic media, and did not show the volume regulatory responses described in dissociated acinar cells.

Animals↗
PubMed1998

Energy consumption associated with fluid and electrolyte transport in the mandibular and parotid glands.

The driving force for Cl- secretion in the salivary acinar cell is believed to be provided by the secondary active uptake of Cl- by Na+ dependent basolateral transporters. The energy cost of primary fluid secretion should therefore reflect the ratio of Na+ entry per mole of Cl- secreted. In the present study, we measured oxygen consumption (QO2) and fluid secretion in perfused mandibular and parotid glands from the rat, and estimated the energy cost of fluid secretion as the ratio of deltaQO2/delta(fluid secretion). During acetylcholine stimulation, the energy cost of fluid secretion by secretory endpieces was higher in the parotid gland than in the mandibular gland. The excess energy cost in the parotid gland may be attributable to other costs than the fluid and electrolyte transport. During bicarbonate-free perfusion in the mandibular gland, bumetanide abolished fluid secretion and QO2 decreased by ca 35%. The remaining QO2 was attributed to Na+ transport activity by basolateral antiports. Assuming values for the energy costs of each transporter and applying these to the total energy cost of the endpieces, the fraction of the total Na+ flux due to Na+/K+/2Cl- cotransport in Na+ handling was estimated to be 0.67. On the other hand, during perfusion with bicarbonate, after subtraction of the bumetanide-sensitive QO2 and the QO2 for antiports, about 19 microl/g/min of QO2 remained, which may be due to activation of Na+/HCO3- cotransport. Thus the inclusion of bicarbonate in the perfusate appears to alter the relative contributions of the various Na+-dependent basolateral transporters to total Na+ handling.

Animals↗
PubMed1998

Time-dependent changes of serum carboxy-terminal peptide of type I procollagen and carboxy-terminal telopeptide of type I collagen concentrations in patients with acute myocardial infarction after successful reperfusion: correlation with left ventricular volume indices.

To test the hypothesis that in patients with acute myocardial infarction (AMI), changes in the concentrations of the serum carboxy-terminal peptide of type I procollagen (PICP) and the carboxy-terminal telopeptide of type I collagen (ICTP) reflect extracellular matrix reformation and degradation, respectively, in the infarct healing processes, we measured these serum concentrations by RIA and compared their values with left ventricular (LV) indices obtained by left ventriculography. We studied 13 consecutive patients with their first AMI who underwent successful reperfusion. Blood samples were taken the day of admission and on days 2, 3, 4, 5, 7, and 14. LV volume indices were determined at 1 month after AMI, when LV remodeling was almost completed. The serum concentrations of both PICP and ICTP changed in a time-dependent manner. The average serum PICP concentration was lower than 1 SD below the mean control values on days 2 and 3 and increased thereafter, returning to the lower end of the control range at day 14. The area under the curve (AUC) for PICP was significantly correlated with the LV end systolic (ES) and end diastolic (ED) volume indices and LV ejection fraction for the first 14 days after AMI. The serum PICP on days 5-14 was inversely correlated or tended to be correlated with the LVES and LVED volume indices. The average serum ICTP concentrations on admission were within the control range, began to increase on day 2, and reached maximal concentrations on day 5, remaining at a plateau concentration until day 14. Although the AUC of ICTP for 14 days, the ICTP concentrations on days 1 and 14, and the minimal and maximal concentrations were significantly correlated with creatine kinase (CK) release and the period from AMI onset to the peak CK time, the concentrations were not significantly correlated with any LV indices except for the concentration on day 4, which was weakly correlated with the LVES volume index. The serum concentrations of PICP showed a significant time-dependent change that correlated with LV indices, indicating that PICP may provide additional information for evaluating the healing process because it affects LV remodeling after AMI. Although the serum concentration of ICTP changed in association with CK release, the ICTP concentration was found to be a poor indicator for LV indices.

Adult↗
PubMed1998

Introduction of an osteopontin gene confers the increase in B1 cell population and the production of anti-DNA autoantibodies.

Osteopontin (OPN) is an Arg-Gly-Asp-containing phosphoprotein that is secreted by activated T cells. The concentration of serum OPN protein is elevated in autoimmune-prone MRL-lpr mice as well as in patients with systemic lupus erythematosus. Previously, it was shown that OPN induces the polyclonal activation of B cells, resulting in the augmented production of immunoglobulin, indicating that OPN plays some role in the development of autoimmune disease. However, the link between OPN and development of autoimmune disease remains unclear. To analyze the role of OPN in immune system and autoimmune diseases, we have generated two kinds of transgenic mice: one carries the immunoglobulin (Ig) enhancer/SV40 promoter and the other carries the cytomegalovirus enhancer/chicken beta-actin (CAG) promoter. In both groups of transgenic mice, the B1 cell population in peritoneal cavity was markedly increased and titer of IgM and IgG3 antibodies in the serum was considerably higher than that in wild-type mice. Most important, the titer of the IgM class of anti-double-stranded DNA antibody was significantly elevated in transgenic mice. These results strongly suggest that OPN may have an important role in the propagation and differentiation of B1 cells and production of autoantibodies.

Animals↗
PubMed1997

High-level expression of exogenous genes by replication-competent retrovirus vectors with an internal ribosomal entry site.

We report the construction of two types of Rous sarcoma virus (RSV)-based replication-competent avian retrovirus vectors, IR1 and IR2 to express an exogenous gene at a very high level. In these vectors, the internal ribosomal entry site (IRES) derived from encephalomyocarditis virus (EMCV) was inserted between the env gene and an exogenous gene. The IR1 vector retains the splicing acceptor site that is present in the downstream of the env gene while the IR2 vector lacks it. Using a v-fos mutant (v-fos-CD3) as an example of exogenous genes, we show here that both IR1 and IR2 vectors expressed the gene product, CD3, at expression levels 5- and 8-fold higher than that of their parental vector without IRES, respectively. These vectors were moderately stable and kept a high-level expression of CD3 for at least three passages through the cells. Analysis of viral transcripts indicate that exogenous genes carried by both IR vectors were translated exclusively from the IRES that is present in all the species of the viral transcripts. High-level expression of exogenous genes was also observed in the case of the Hoxa-13 gene in the IR1 vector or the fra-2 gene in the IR2 vector, indicating that the extremely high-level expression characteristic of these vectors is applicable to several exogenous genes.

Animals↗
PubMed1997

Conformational changes in seventeen cystine disulfide bridges of bovine serum albumin proved by Raman spectroscopy.

Conformational changes in cystine disulfide bridges of bovine serum albumin during acid-induced isomerization (N --> F and F --> E transitions) have been studied with Raman spectroscopy. In an X-ray crystallographic study of human serum albumin, Carter and Ho reported that all disulfide bridges of the albumin molecule are in the gauche-gauche-gauche conformation [1]. On the other hand, the solution structure of bovine serum albumin examined by Raman spectroscopy differs from its crystal structure in the conformation of some of the disulfide bridges. Two Raman bands were detected at 520 and 505 cm(-1) in the disulfide stretching mode region, suggesting that the 17 disulfide bridges in the N-form of bovine serum albumin solution take both the gauche-gauche-gauche and gauche-gauche-trans conformations. The ratio of the peak intensities at 520 and 505 cm(-1) (I505/I520) is increased from 1.6 to 2.1 and from 2.1 to 6.3 on going from the N- to the F-form and from the F- to the E-form, respectively, indicating that the gauche-gauche-trans conformation of the disulfide bridges is converted to a gauche-gauche-gauche one which is the most energetically stable form during the acid-induced isomerization. However, small amounts of gauche-gauche-trans conformation still remain even in the E-form.

Animals↗
PubMed1997

The perturbed membrane of cells undergoing apoptosis is susceptible to type II secretory phospholipase A2 to liberate arachidonic acid.

Several lines of evidence have suggested that the plasma membranes of cells elicited by proinflammatory stimuli or microvesicles shed from activated cells are sensitive to extracellular type II secretory phospholipase A2 (sPLA2) that liberates fatty acids and lysophospholipids. Here we report that the membranes of cells undergoing apoptosis are highly susceptible to type II sPLA2. When neuronally differentiated rat pheochromocytoma PC12 cells deprived of nerve growth factor and serum, mouse mast cells deprived of hematopoietic cytokines or human monocytic U937 cells stimulated via Fas antigen (a receptor for the death factor Fas ligand), were exposed to type II sPLA2 at concentrations comparable to those detected at inflamed sites, the release of arachidonic acid was significantly accelerated in association with the process of programmed cell death. Arachidonic acid release by sPLA2 was dependent on the extracellular Ca2+ and was accompanied by preferential hydrolysis of phosphatidylethanolamine and phosphatidylserine in the membrane phospholipids. Association of sPLA2 with cell surface proteoglycan, which has been shown to be a prerequisite for endogenous sPLA2-dependent arachidonic acid release from the plasma membranes of live cells, was not essential for sPLA2-mediated hydrolysis of apoptotic cell membranes. Taking these results together, the apoptotic cell membrane is a potential target for extracellular type II sPLA2. The present findings may be relevant to events occurring at inflammatory or ischemic disease sites where apoptotic cells accumulate.

Animals↗
PubMed1997

Selective antigen presenting activity of cortical thymic epithelial cells against CD4+ T cells associated with both lack of costimulatory molecules and inefficient presentation of MHC-peptide ligands.

Selective activation among several effector functions of a T cell clone, DB14, specific for pigeon cytochrome c 43-58 (p43-58) and restricted to I-Ab/d was induced by antigen (Ag) presentation with nonprofessional Ag-presenting cells (APC), cortical thymic epithelial cells (c-TEC) (B7-1- CD40-), whereas full activation of the DB14 was induced with another nonprofessional APC, I-Ab L cell (B7-1+ CD40+). In the present study, to elucidate the mechanism underlying the selective activation of DB14 cells by c-TEC, we established c-TEC transfected with human CD40 alone (huCD40-c-TEC) or both human CD40 and murine B7-1 (huCD40/mB7-1-c-TEC), and compared the APC functions with those of the original c-TEC and I-Ab L cell. IFN-gamma production but not the proliferative response of DB14 was elevated by Ag presentation with huCD40-c-TEC as compared with unmanipulated c-TEC. On the other hand, upon stimulation with Ag plus huCD40/mB7-1-c-TEC both a significant proliferative response and IFN-gamma production were induced in DB14. However, the level of these responses did not reach that induced in the presence of I-Ab L cell. A similar pattern of APC functions was demonstrated with the other B7-independent T cell clone, PAB3, or T cell hybridomas (DBhy22 and BD7-5) which are basically independent of costimulation for the activation. The present finding along with our previous report that several structural differences of I-Ab molecules are present between c-TEC and I-Ab L cell suggests that the distinct APC activity of c-TEC is attributable not only to a lack of B7-1 and CD40 but also to inefficient presentation of MHC-peptide complex on the c-TEC.

Animals↗
PubMed1997

Tertiary hypothyroidism and hyperglycemia in mice with targeted disruption of the thyrotropin-releasing hormone gene.

Thyrotropin-releasing hormone (TRH) is a brain hypothalamic hormone that regulates thyrotropin (TSH) secretion from the anterior pituitary and is ubiquitously distributed throughout the brain and other tissues including pancreas. To facilitate studies into the role of endogenous TRH, we have used homologous recombination to generate mice that lack TRH. These TRH-/- mice are viable, fertile, and exhibit normal development. However, they showed obvious hypothyroidism with characteristic elevation of serum TSH level and diminished TSH biological activity. Their anterior pituitaries exhibited an apparent decrease in TSH immunopositive cells that was not due to hypothyroidism. Furthermore, this decrease could be reversed by TRH, but not thyroid hormone replacement, suggesting a direct involvement of TRH in the regulation of thyrotrophs. The TRH-/- mice also exhibited hyperglycemia, which was accompanied by impaired insulin secretion in response to glucose. These findings indicate that TRH-/- mice provide a model of exploiting tertiary hypothyroidism, and that TRH gene abnormalities cause disturbance of insulin secretion resulting in marked hyperglycemia.

Animals↗
PubMed1997

Detection of DNA lesions induced by chemical mutagens using the single-cell gel electrophoresis (comet) assay. 2. Relationship between DNA migration and alkaline condition.

The alkaline condition is an important factor for the alkaline single-cell gel electrophoresis (SCG) assay to detect the genotoxic effects of chemicals. In order to understand the relationship between DNA migration and alkaline condition, the effect of 13 model chemical mutagens with different modes of action was evaluated with the alkaline SCG assay under two different alkaline conditions (pH 12.1 and 12.6). CHO cells were sampled just after treatment for 1 h. The X-ray mimetic mutagen BLM increased DNA migration at pH 12.1 and 12.6 and the results were the same at both pH values. Six alkylating mutagens MNU, ENU, MNNG, ENNG, MMS, and EMS and one base adduct inducer 4-NQO induced a dose-dependent response only at pH 12.6. Two DNA crosslinking agents, MMC and DDP, and AMD had negative results. MMC and DDP, however, reduced the positive response of BLM, suggesting that DNA crosslinks could be detected. These results demonstrated that the alkaline condition was important factor for the alkaline SCG assay to detect the genotoxic effects of chemicals.

Alkylating Agents↗