Search PubMed⌕ Search

Biomedical subjects

A Maeda

Publications and source records attributed to A Maeda.

At least 181 records · Page 10Linked to original sources
PubMed1997

Random migration of polymorphonuclear leukocytes induced by GM-CSF involving a signal transduction pathway different from that of fMLP.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) induced random migration of human polymorphonuclear leukocytes (PMNs) but not chemotaxis. Chemoattractants such as N-formyl-methionyl-leucyl-phenylalanine (fMLP), leukotriene B4 (LTB4), and interleukin-8 (IL-8) induced both random migration and chemotaxis. Other inflammatory cytokines, including granulocyte colony-stimulating factor (G-CSF), interleukin 1alpha (IL-1alpha), and tumor necrosis factor alpha (TNF-alpha), did not induce either movement. One-minute exposure of PMNs to GM-CSF was sufficient for the induction of random migration, whereas fMLP-induced random migration required continued presence of fMLP. Inhibitors of phosphatidylinositol 3-kinase (PI3-K), protein kinase C (PKC), and protein tyrosine kinase (PTK) had no effect on random migration induced by GM-CSF, whereas fMLP-induced movements were partially inhibited by PTK inhibitors but not by inhibitors of PI3-K inhibitors nor PKC inhibitors. Myosin light chain kinase inhibitors inhibited movements of PMNs induced by both GM-CSF and fMLP. These findings also imply that some aspects of the signal transduction pathway of GM-CSF leading to random migration is different from that of fMLP. Our findings suggest that cell movements are controlled through diverse signal transduction systems.

Androstadienes↗
PubMed1997

Leukotriene B4-activated human endothelial cells promote transendothelial neutrophil migration.

We explored the effect of leukotriene B4 (LTB4) on endothelial cells in LTB4-induced transendothelial migration (TEM) of neutrophils as an in vitro model of neutrophil extravasation. Chemotactic response of human neutrophils to LTB4 was significantly lower than that in response to N-formyl-methionyl-leucyl-phenylalanine (fMLP), whereas the extent of TEM in response to LTB4 was significantly higher than that to fMLP. The study on random migration induced by LTB4 and fMLP also showed similar results, which indicated that LTB4 might affect the human umbilical cord vein endothelial cell (HUVEC) barrier. Neutrophil TEM was induced by pretreatment of HUVEC monolayer with LTB4 but not with fMLP. Treatment of endothelial cells by ONO-4057, a LTB4 receptor antagonist, abolished the effect of LTB4 almost completely whereas neutrophils treated with ONO-4057 could transmigrate through HUVEC treated with LTB4. These findings indicated that LTB4 could induce neutrophil TEM by acting on HUVEC.

Cell Movement↗
PubMed1997

Continuous haemodiafiltration during and after cardiopulmonary bypass in renal failure patients.

PURPOSE: Continuous haemodiafiltration (CHDF) is a technique enhancing the efficiency of solute clearance of haemofiltration by infusing dialysis fluid through the haemofilter. It has been reported to control water and electrolyte balance continuously without haemodynamic instability in critically ill patients with renal failure, Therefore, we used CHDF during and after cardiopulmonary bypass (CPB) in two renal failure patients, and discuss its efficacy. CLINICAL FEATURES: The first patient undergoing aortic valve replacement had dialysis-dependent renal failure. Chronic renal failure in the second patient undergoing mitral valve replacement and coronary revascularization was controlled preoperatively with diuretics. In both cases, CHDF was performed not only during CPB but also in the post-CPB period. Serum concentrations of potassium, urea and creatinine were well-controlled in spite of large amount of blood transfused in the post-CPB period (1000 ml fresh blood and 400 ml fresh frozen plasma in the fist patient, and 1400 ml fresh blood in the second patient). There was no difficulty in haemostasis during the use of nafamostat mesilate as an anticoagulant to keep activated clotting time at about 150 sec for CHDF in the post-CPB period. CONCLUSION: Our initial experiences of CHDF during and after CPB suggest that the technique provides excellent electrolyte, metabolite and fluid management for the cardiac patients with chronic renal failure. Combined with nafamostat mesilate for anticoagulation, CHDF was simple and safe and did not increase the risk of bleeding.

Adult↗
PubMed1997

Oral temperatures of the elderly in nursing homes in summer and winter in relation to activities of daily living.

This study was conducted to clarify the seasonal difference in body temperature in summer and winter, and to document the thermal environment of the elderly living in nursing homes. The subjects were 57 healthy elderly people aged > or = 63 years living in two nursing homes in Japan. One of the homes was characterized by subjects with low levels of activities of daily living (ADL). Oral temperatures were measured in the morning and afternoon, with simultaneous recording of ambient temperature and relative humidity. Oral temperatures in summer were higher than in winter, with statistically significant differences (P < 0.05) of 0.25 (SD 0.61) degree C in the morning and 0.24 (SD 0.50) degree C in the afternoon. Differences between oral temperatures in summer and winter tended to be greater in subjects with low ADL scores, even when their room temperature was well-controlled. In conclusion, the oral temperatures of the elderly are lower in winter than summer, particularly in physically inactive people. It appears that those with low levels of ADL are more vulnerable to large changes in ambient temperature.

Activities of Daily Living↗
PubMed1997

Localization and orientation of functional water molecules in bacteriorhodopsin as revealed by polarized Fourier transform infrared spectroscopy.

Linear dichroic difference Fourier transform infrared spectra upon formation of the M photointermediate were recorded with oriented purple membranes. The purpose was to determine the angle of the directions of the dipole moments of 1) the water molecule whose O-H stretching vibration appears at 3643 cm-1 for the unphotolyzed state and 3671 cm-1 for the M intermediate, and 2) the C=O bond of protonated Asp85 in the M intermediate. The angle of 36 degrees we find for the C=O of the protonated Asp85 in the M intermediate is not markedly different from 26 degrees for unprotonated Asp85 in the model based on cryoelectron diffraction, indicating the absence of gross orientation changes in Asp85 upon its protonation. The O-H band at 3671 cm-1 of a water molecule in the M intermediate, although its position has not determined, is fixed almost parallel to the membrane plane. For the unphotolyzed state the angle of the water O-H to the membrane normal was determined to be 60 degrees. On the basis of these data and the structural model, we place the water molecule in the unphotolyzed state at a position where it forms hydrogen bonds with the Schiff base, Asp85, Asp212, and Trp86.

Aspartic Acid↗
PubMed1997

Human hepatocyte growth factor in bile: an indicator of posthepatectomy liver function in patients with biliary tract carcinoma.

We measured the concentration of hepatocyte growth factor (HGF) in bile obtained from patients after hepatectomy. The HGF concentrations in the bile samples were quantified using an enzyme-linked immunosorbent assay (ELISA). By immunoblotting, using a monoclonal antibody raised against the HGF alpha-subunit, the bile HGF, which was purified on a Heparin-Sepharose column, showed a band of the same size as the recombinant HGF alpha-subunit (69 kd). Bile samples were obtained from 24 patients with biliary tract disease before and after hepatectomy by means of biliary drainage. Before surgery, the bile HGF concentrations were minimal (0.8 +/- 0.1 ng/mL); however, after hepatectomy on postoperative day 1 in patients without posthepatectomy liver failure (20 of 24), they increased severalfold (4.1 +/- 0.4 ng/mL, P < .05). The patients with posthepatectomy liver failure (4 of 24) showed no significant increase in bile HGF after hepatectomy (less than 2 ng/mL on postoperative day 1). The volume of the remnant liver correlated positively with the bile HGF concentration. The bile HGF concentration on postoperative day 1 exhibited a significant negative correlation with the maximum concentration of serum total bilirubin after hepatectomy. The concentration of bile HGF was generally higher than that in serum (2.1-fold). Thus, the bile HGF concentration after hepatectomy may be useful for the early assessment of posthepatectomy liver function.

Adult↗
PubMed1997

Intramembrane signaling mediated by hydrogen-bonding of water and carboxyl groups in bacteriorhodopsin and rhodopsin.

The light-induced mechanism for proton pumping of bacteriorhodopsin was studied by Fourier transform infrared spectroscopy of the discrete sequential intermediate states, L, M, and N. Attention is focused on L in the early microsecond time range, as a transition state in which the Schiff base forms strong H-bonding with a water molecule coordinated with Asp85. This structure leads to transfer of the Schiff base proton to Asp85 in the L-to-M process, which then triggers proton release from Glu204 to the extracellular surface. H-bonding of Arg82 and water molecules are involved in this process. Chloride can replace Asp85 in the D85T mutant, and this anion will be then transported instead of a proton. In L, structural perturbations are induced also around Asp96, through a string of H-bonding mediated by internal water molecules and peptide carbonyls in helices B and C, and Trp182 in helix F. These may cause the structural changes that occur later in the M-to-N process. Similar interactions, through internal water molecules and the peptide bonds in helices B and C, take place in bovine rhodopsin. They transduce changes across the membrane from the Schiff base to the cytoplasmic surface, where the activation of the transducin occurs.

Animals↗
PubMed1997

Transmembrane signaling mediated by water in bovine rhodopsin.

Unhydrated air-dried films of rhodopsin from bovine rod outer segment membranes do not produce its active state, metarhodopsin II. In order to reveal requirements for its formation, we studied changes in H-bonding of water, peptide carbonyl and carboxylic acid in the photochemical reactions by means of difference Fourier transform infrared spectroscopy, under both hydrated and unhydrated conditions. A water molecule near Glu113, which undergoes H-bonding change in bathorhodopsin, remained in the unhydrated film, but with a weaker H-bonding state than in the hydrated film. The other water molecules, which shfit in lumirhodopsin and metarhodopsin I as well as in bathorhodopsin of the hydrated film, were not observed in the unhydrated film. Effects of the dehydration were detected in all the C=O stretching vibrations of the peptide backbone and of Asp83 in the formation of bathorhodopsin. The C=O stretching band of Asp83 of lumirhodopsin and metarhodopsin I is intensified in the unhydrated film. We propose that structural changes at the intradiscal site in the interaction between the Schiff base and Glu113 affect water molecules, the peptide backbone, Asp83 and Glu122 in helices B and C through consecutive photochemical processes to metarhodopsin II.

Animals↗
PubMed1997

Interleukin-12 gene expression in human monocyte-derived macrophages stimulated with Mycobacterium bovis BCG: cytokine regulation and effect of NK cells.

Macrophage-derived interleukin-12 (IL-12) is essential for the activation of a protective immune response against intracellular pathogens. In this study, we examined the regulation of IL-12 mRNA expression by monocyte-derived macrophages (MDM) in response to Mycobacterium bovis BCG stimulation. A reverse transcription-PCR assay detected p40 mRNA of IL-12 at 3 h and showed a peak at 6 to 12 h with a subsequent decline. Semiquantitation of mRNA levels by competitive PCR revealed that pretreatment with gamma interferon (IFN-gamma) amplified the expression approximately 100-fold, while pretreatment with tumor necrosis factor alpha (TNF-alpha) or granulocyte-macrophage colony-stimulating factor augmented this expression about 10-fold. In contrast, pretreatment with IL-10 and IL-4 inhibited IL-12 mRNA expression. These results were further confirmed by measuring the p70 bioactive protein level in each conditioned medium by an enzyme-linked immunosorbent assay. Since IL-12 mRNA expression was weak without cytokine pretreatment and IFN-gamma strongly augmented production, we speculated that IFN-gamma might have a role in BCG stimulation of IL-12 mRNA expression. Unexpectedly, the addition of three different kinds of anti-IFN-gamma antibodies and anti-IFN-gamma receptor antibody and the coaddition of anti-TNF-alpha antibody with anti-IFN-gamma receptor antibody all failed to inhibit IL-12 mRNA expression. However, the MiniMACS method used to remove NK cells from a mononuclear cell suspension inhibited the expression of p40 mRNA but not the expression of mRNA of TNF-alpha or IL-1beta. We concluded that the coexistence of NK cells was essential for the induction of IL-12 in MDM stimulated with BCG rather than through the secretion of IFN-gamma.

Cytokines↗
PubMed1997

Effects of neutrophil elastase inhibitor on bleomycin-induced pulmonary fibrosis in mice.

Neutrophils play an important role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). To elucidate the possible involvement of neutrophil elastase (NE) in pulmonary fibrosis, we investigated the efficacy of a new specific NE inhibitor (ONO-5046 Na) in a murine model of human IPF, bleomycin-induced pulmonary fibrosis. Bronchoalveolar lavage (BAL) and histopathological analysis were performed on bleomycin-treated mice (group A), bleomycin and ONO-5046 Na-treated mice (group B), and saline control groups at 1, 15, and 29 d after the end of bleomycin treatment. At 29 d, multifocal fibrosis was observed in group A, whereas no fibrotic regions were observed in group B. Interleukin-1 beta and macrophage inflammatory protein-2 mRNA levels in BAL cells on day 1, and platelet-derived growth factor-A and insulin-like growth factor-1 mRNA levels on days 1 and 15, were significantly lower in group B than in group A. Thus, we demonstrated an inhibitory effect of ONO-5046. Na on pulmonary fibrosis in mice, indicating the involvement of NE in the pathogenesis of pulmonary fibrosis. We propose that this effect might be related to suppressed expression of particular cytokines in alveolar macrophages and that this specific NE inhibitor could be a novel therapeutic agent for IPF.

Animals↗
PubMed1997

Resistance to infection with mouse hepatitis virus (MHV) in the cell clones derived from persistently infected DBT cells with the JHM strain of MHV.

PiD-10 and piD-11 cells that have been established from persistently infected DBT cells with the JHM strain of MHV (JHMV) were resistant to infection with JHMV. There was no significant difference in the amount of adsorbed virus among piD-10, piD-11 and DBT cells. When an expression of mRNA of the MHV receptor in piD-10 and piD-11 cells was analyzed by the RT-PCR method, no significant difference was observed in the intensities of the amplified products among piD-10, piD-11 and DBT cells. Treatment of virus-adsorbed cells with PEG, which induces fusion of the cellular membrane with the viral envelop, causes entry of virus particles into cells. There was no significant difference in the yields of virus between PEG-treated and PEG-untreated cells. The titers of infectious virus internalized into piD-10 and piD-11 cells were the same as those in DBT cells. When piD-10 and piD-11 cells were fused with PEG and infected with JHMV, the yields of infectious virion particles from the fused cells between piD-10 and piD-11 cells were significantly lower than those from the fused cells between DBT and piD-10 or piD-11 cells. The present study showed that resistance of piD-10 and piD-11 cells to JHMV infection is not due to an inhibition of JHMV entry into the cells.

Animals↗
PubMed1997

Remodeling of allogeneic and autogenous patellar tendon grafts in rats.

The differences in remodeling among frozen allografts, frozen autografts, and fresh autografts were investigated using a patellar tendon transplantation model in 2 different strains of rats. In this study, isografting (transplantation among the same strain inbred animals) was adopted as an autograft model. This method makes it possible to set up a frozen autograft model. Evaluation included mechanical properties determined during tensile failure tests, cross sectional area, histologic findings, and collagen fibril distribution. Recipient rats were euthanized at 4, 8, 12, and 24 weeks after transplantation (n = 5, in each group and in each period). The frozen allografts showed significantly less tensile strength than did the frozen autografts at 4 weeks, but this difference was transient and diminished by 8 weeks. The tensile strength of the fresh autografts was significantly greater than that of the frozen autografts at 8 weeks or the frozen allografts at 8 and 12 weeks. It was suggested that freeze thawing has adverse effects on the remodeling of fresh autografts in this extraarticular graft model. The cross sectional area for each type of graft at each posttransplantation period was about twice as large as that before transplantation. The collagen fibril profile of the frozen allografts was similar to that of the frozen autografts. However, the fresh autografts showed a greater number of large diameter fibrils and a lesser number of small diameter fibrils than did the other 2 frozen groups.

Animals↗
PubMed1997

Effects of ethane-1-hydroxy-1, 1 diphosphonate on Dunn osteosarcoma cells.

We investigated the effects of ethane-1-hydroxy-1, 1 diphosphonate (EHDP) on Dunn osteosarcoma cells in vivo and in vitro. In in vivo study, an increase of tumor volume was significantly suppressed in the EHDP administered groups compared with the control group. Histologically, Dunn osteosarcoma cells' viability was maintained after EHDP administration. However, fatty degeneration of tumor tissue was suspected in two of eight mice in the 5.0 mg/kg EHDP administered group. In vitro study, EHDP inhibited DNA synthesis and induced morphological changes, such as pycnotic cells. These findings show that the growth of Dunn osteosarcoma cells is inhibited by EHDP.

Alkaline Phosphatase↗
PubMed1997

[Blood rheological study in rats with fatty liver--with special reference to effects of ethyl icosapentate].

A blood rheological study was conducted using Kikuchi's micro-channel method in rats with fatty liver. Effects of eicosapentaenoic acid (EPA) on blood rheology were also evaluated. Male SD rats given normal feed served as the control. One group was given choline-deficient feed for 4 weeks (EPA (-) group), while another group was daily given EPA (1000 mg/kg) for 4 weeks together with choline-deficient feed (EPA (+) group). The micro-channel passage time was determined using 100 microliters of whole blood. The passage time significantly increased in the EPA (-) group compared to the control (p < 0.01). It significantly decreased in the EPA (+) group compared to the EPA (-) group (p < 0.01). Findings obtained in the present study suggested that blood rheological factors are related to the development of fatty liver and that EPA inhibits fatty changes of the liver by improving these rheological factors.

Animals↗
PubMed1997

[Assessment of myocardial perfusion hemodynamics using echo planar MR imaging].

It was possible to obtain images for individual heart beats using single-shot Echo Planar Imaging(EPI), and changes of myocardial signal intensity could be assessed visually after GD-DTPA administration. Measurement of the same site in the myocardium on myocardial perfusion images for individual heart beats was facilitated by imaging during breath-holding, and accurate evaluation was possible. In patients with coronary artery disease, the site of myocardial infarction tended to show less increase in signal intensity than the normal myocardium, and could easily be distinguished from normal myocardium according to the change in signal intensity. In patients with atrial fibrillation, the signal intensity of the myocardium varied with each heart beat, and it was difficult to assess perfusion hemodynamics. Myocardial perfusion studies using EPI still present problems with respect to spatial resolution, but the myocardial perfusion hemodynamics for individual heart beats can be determined by preparing time/intensity curves. It is also possible to obtain information on cardiac morphology, wall motion, and myocardial metabolism in addition to perfusion data by combining myocardial perfusion studies with methods such as high speed cine MRI, tagging, or myocardial MRS. It is possible that this method will also be useful in studying myocardial viability.

Coronary Circulation↗
PubMed1997

Effects of dibutyryl cyclic adenosine monophosphate on nucleolar organizer regions and epidermal growth factor receptor of Dunn osteosarcoma cells.

We investigated the characteristics of nucleolar organizer regions (NORs) and epidermal growth factor receptor (EGFR) on differentiated Dunn osteosarcoma in response to dibutyryl cyclic adenosine 3',5'-monophosphate (Bt2cAMP). In the presence of 3 mM Bt2cAMP, the mean number of NORs was significantly decreased in 24 hrs and 48 hrs compared with the untreated group. Also, EGFR affinity was decreased and the EGFR number was increased in response to the cellular differentiation by Bt2cAMP. The decrease in EGFR affinity might be considered as an indicator of differentiation or the mature state of the cells. Thus, the present study provides a new clue to support differentiation of osteosarcoma cells from the viewpoint of NORs findings and EGFR analysis as a differentiation marker.

Animals↗
PubMed1996

Relationship of retinal configuration and internal proton transfer at the end of the bacteriorhodopsin photocycle.

In the last step of the bacteriorhodopsin photocycle the initial state is regenerated from the O intermediate in an essentially unidirectional reaction. Comparison of the rate of this photocycle step and the rate of deprotonation of Asp-85 in pH jump experiments with various site-specific mutants indicates that recovery of the initial state is influenced by (1) residues such as Glu-204 that affect deprotonation of Asp-85 and (2) residues such as Leu-93 that contact the retinal and therefore must affect its thermal reisomerization from 13-cis to all-trans as suggested by Delaney, Schweiger, and Subramaniam (Proc. Natl. Acad. Sci. U.S.A. 92, 11120-11124, 1995). These results, together with FTIR spectra (Kandori, Hatanaka, Yamazaki, Needleman, Brown, Richter, Lanyi, & Maeda, manuscript in preparation) of the last intermediate in the photocycles of representatives of the two kinds of mutants, E204Q and L93M, suggest the following sequence of events: reisomerization of the retinal from 13-cis to an all-trans configuration that contains a twisted chain (with high amplitude hydrogen out-of-plane vibrational bands) triggers proton transfer from Asp-85 to Glu-204 or directly to the extracellular surface, and the proton transfer in turn triggers relaxation of the twist in the retinal. The involvement of the proton transfer in the kinetics of this sequence suggests the reason for the unidirectionality of the overall reaction: upon reisomerization of the retinal the very low pKa of Asp-85 in the unphotolyzed protein is reestablished and this residue thereby becomes a good proton donor.

Aspartic Acid↗