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Biomedical subjects

M Yamaguchi

Publications and source records attributed to M Yamaguchi.

At least 289 records · Page 16Linked to original sources
PubMed2000

Stimulation of prostaglandin E2 and interleukin-1beta production from old rat periodontal ligament cells subjected to mechanical stress.

Although the severity of periodontal disease is known to be affected by the age of the host, the pathological role of aging in periodontal disease, especially that attributable to trauma from occlusion, has not been well characterized. Prostaglandin (PG)E2 and interleukin (IL)-1beta are key mediators involved in periodontal diseases, potent stimulators of bone resorption, and are produced by human periodontal ligament (PDL) cells in response to mechanical stress. To investigate age-related changes in the biosynthetic capacity of PGE2 and IL-1beta in PDL cells, we examined the effects of in vivo aging with mechanical tension on PGE2 and IL-1beta expression by rat PDL cells. PDL cells obtained from the incisors of 6-week (young) and 60-week (old) rats were cultured on flexible-bottomed culture plates. The cells were deformed by causing a 9% or 18% increase in surface area at 6 cycles per minute for 1 to 5 days. We found an approximately twofold increase in PGE2 and IL-1beta production by old PDL cells subjected to mechanical tension compared with that by young cells, although the constitutive levels were similar in both. The expression of cyclooxygenase (COX)-2 and IL-1beta mRNA (messenger ribonucleic acid) was enhanced by mechanical tension as determined by use of reverse transcription-polymerase chain reaction (RT-PCR), whereas COX-1 and IL-1beta-converting enzyme mRNA remained unchanged. It is possible that the large amount of PGE2 and IL-1beta produced by PDL cells from an aged host in response to mechanical force may be positively related to the acceleration of alveolar bone resorption.

Aging↗
PubMed2000

Stress-induced factor involved in flower formation of Lemna is an alpha-ketol derivative of linolenic acid.

A stress-induced substance(s) (factor C) incubated with norepinephrine (NE) has strong flower-inducing activity in Lemna paucicostata. We isolated an essential component (FIF) of factor C, and clarified its chemical structure as 9-hydroxy-10-oxo-12(Z),15(Z)-octadecadienoic acid, an alpha-ketol derivative of linolenic acid, which is formed via 9-hydroperoxy linolenic acid. Synthesized FIF showed flower-inducing activity after incubation with NE (factor C activity) equivalent to that formed in the stressed Lemna. Jasmonic acid and 13-hydroxy-12-oxo-9(Z),15(Z)-octadecadienoic acid (12,13-alpha-ketol linolenic acid), both of which are formed via 13-hydroperoxide of linolenic acid and all other derivatives of FIF synthesized by chemical and enzymatic processes failed to show the factor C activity. These results suggest that the molecular structure of FIF is very specific for the factor C activity.

Fatty Acids, Unsaturated↗
PubMed2000

Molecular and biochemical characterization of a novel hydroxycinnamoyl-CoA: anthocyanin 3-O-glucoside-6"-O-acyltransferase from Perilla frutescens.

We have isolated and characterized a cDNA, PfAT208, encoding hydroxycinnamoyl-CoA: anthocyanin 3-O-glucoside-6"-O-acyltransferase (3AT) from Perilla frutescens. The identity of the cDNA was established by determination of the reaction products with recombinant enzyme overexpressed in Escherichia coli. The deduced amino acid sequence has a few regions that are conserved in a CoA-dependent acyltransferase family. The recombinant enzyme produced in yeast could utilize cyanidin 3-glucoside and cyanidin 3,5-diglucoside, putative substrates in vivo, as well as other anthocyanins. The inhibitory effects of diethyl pyrocarbonate and N-ethylmaleimide on the recombinant 3AT activities suggest that histidine and cysteine residues are important for their catalytic function. These properties are in common with anthocyanin 5-O-glucoside-6"-O-acyltransferase (5AT). In Northern analysis, a transcript of PfAT208 was detected in the young leaves of perilla red forma. The properties of other cDNAs, gentian GAT106 and petunia PhAT48, isolated during the above cloning procedure are also described.

Acyl Coenzyme A↗
PubMed2000

Mechanism of the chilling-induced decrease in proton pumping across the tonoplast of rice cells.

The ATP-generated proton pumping across tonoplast vesicles from chilling-sensitive Boro rice (Oryza sativa L. var. Boro) cultured cells was markedly decreased by chilling at 5 degrees C for 3 d. The membrane fluidity of core hydrophobic and surface hydrophilic regions of the lipid bilayer was measured by steady-state fluorescence depolarization of 1,6-diphenyl-1,3,5-hexatriene and trimethylammonium 1,6-diphenyl-1,3,5-hexatriene and by electron spin resonance spectroscopy of 16- and 5-doxyl stearic acid, respectively. The fluidity of the surface region of the lipid bilayer of the tonoplast vesicles decreased by chilling. The fluidity of the surface region of the liposomes and the proton pumping across the reconstituted proteoliposomes with tonoplast H+-ATPase decreased with increasing content of the glycolipids. The proton pumping across chimera proteoliposomes was reduced by chilling only when it was reconstituted in the presence of tonoplast glycolipids from chilled Boro cells. These data suggest that the reduction in ATP-generated proton pumping across the tonoplast by chilling is due to the decrease in the fluidity of the surface region of the lipid bilayer of the tonoplast, which is caused by the changes in glycolipids.

Fluorescence Polarization↗
PubMed2000

In vitro activities of rabeprazole, a novel proton pump inhibitor, and its thioether derivative alone and in combination with other antimicrobials against recent clinical isolates of Helicobacter pylori.

The MICs of rabeprazole sodium (RPZ), a newly developed benzimidazole proton pump inhibitor (PPI), against 133 clinical Helicobacter pylori strains revealed a higher degree of activity than the another two PPIs, lansoprazole and omeprazole. Time-kill curve assays of RPZ, when combined with amoxicillin, clarithromycin, or metronidazole, disclosed that synergistic effects were demonstrated in combination with each antibiotic examined. Moreover, no apparent antagonistic effect appeared among all of the strains tested.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2000

Viral impacts on total abundance and clonal composition of the harmful bloom-forming phytoplankton Heterosigma akashiwo.

Recent observations that viruses are very abundant and biologically active components in marine ecosystems suggest that they probably influence various biogeochemical and ecological processes. In this study, the population dynamics of the harmful bloom-forming phytoplankton Heterosigma akashiwo (Raphidophyceae) and the infectious H. akashiwo viruses (HaV) were monitored in Hiroshima Bay, Japan, from May to July 1998. Concurrently, a number of H. akashiwo and HaV clones were isolated, and their virus susceptibilities and host ranges were determined through laboratory cross-reactivity tests. A sudden decrease in cell density of H. akashiwo was accompanied by a drastic increase in the abundance of HaV, suggesting that viruses contributed greatly to the disintegration of the H. akashiwo bloom as mortality agents. Despite the large quantity of infectious HaV, however, a significant proportion of H. akashiwo cells survived after the bloom disintegration. The viral susceptibility of H. akashiwo isolates demonstrated that the majority of these surviving cells were resistant to most of the HaV clones, whereas resistant cells were a minor component during the bloom period. Moreover, these resistant cells were displaced by susceptible cells, presumably due to viral infection. These results demonstrated that the properties of dominant cells within the H. akashiwo population change during the period when a bloom is terminated by viral infection, suggesting that viruses also play an important role in determining the clonal composition and maintaining the clonal diversity of H. akashiwo populations. Therefore, our data indicate that viral infection influences the total abundance and the clonal composition of one host algal species, suggesting that viruses are an important component in quantitatively and qualitatively controlling phytoplankton populations in natural marine environments.

DNA Viruses↗
PubMed2000

Role of activated protein C in Helicobacter pylori-associated gastritis.

The protein C (PC) pathway has recently been suggested to play a role in the regulation of the inflammatory response. To further extend the anti-inflammatory effect of activated PC (APC) in vivo, particularly its biological relevance to human disease, the activity of APC in the mucosa of patients with Helicobacter pylori-associated gastritis and the effect of vacuolating cytotoxin (VacA), cytotoxin-associated antigen (CagA), and H. pylori lipopolysaccharide (LPS) on PC activation were evaluated. This study comprised 35 patients with chronic gastritis. There were 20 patients with and 15 without H. pylori infection. The levels of PC and APC-PC inhibitor (PCI) complex were measured by immunoassays. The level of PC was significantly decreased and the level of APC-PCI complex was significantly increased in biopsy specimens from gastric corpus and antrum in patients with H. pylori-associated gastritis as compared to H. pylori-negative subjects. The concentrations of VacA, CagA, and LPS were significantly correlated with those of the APC-PCI complex in biopsy mucosal specimens from the gastric corpus and antrum. H. pylori LPS, VacA, and CagA induced a dose-dependent activation of PC on the surface of monocytic cells. APC inhibited the secretion of tumor necrosis factor alpha (TNF-alpha) induced by H. pylori LPS. Overall, these results suggest that H. pylori infection is associated with increased APC generation in the gastric mucosa. The inhibitory activity of APC on TNF-alpha secretion may serve to protect H. pylori-induced gastric mucosal damage.

Antigens, Bacterial↗
PubMed2000

Role of cell shape in determination of the division plane in Schizosaccharomyces pombe: random orientation of septa in spherical cells.

The establishment of growth polarity in Schizosaccharomyces pombe cells is a combined function of the cytoplasmic cytoskeleton and the shape of the cell wall inherited from the mother cell. The septum that divides the cylindrical cell into two siblings is formed midway between the growing poles and perpendicularly to the axis that connects them. Since the daughter cells also extend at their ends and form their septa at right angles to the longitudinal axis, their septal (division) planes lie parallel to those of the mother cell. To gain a better understanding of how this regularity is ensured, we investigated septation in spherical cells that do not inherit morphologically predetermined cell ends to establish poles for growth. We studied four mutants (defining four novel genes), over 95% of whose cells displayed a completely spherical morphology and a deficiency in mating and showed a random distribution of cytoplasmic microtubules, Tea1p, and F-actin, indicating that the cytoplasmic cytoskeleton was poorly polarized or apolar. Septum positioning was examined by visualizing septa and division scars by calcofluor staining and by the analysis of electron microscopic images. Freeze-substitution, freeze-etching, and scanning electron microscopy were used. We found that the elongated bipolar shape is not essential for the determination of a division plane that can separate the postmitotic nuclei. However, it seems to be necessary for the maintenance of the parallel orientation of septa over the generations. In the spherical cells, the division scars and septa usually lie at angles to each other on the cell surface. We hypothesize that the shape of the cell indirectly affects the positioning of the septum by directing the extension of the spindle.

Cell Division↗
PubMed2000

Limitations of vitek GPS-418 cards in exact detection of vancomycin-resistant enterococci with the vanB genotype.

The susceptibilities of 20 strains of vancomycin-resistant enterococci (VRE) with the vanB genotype obtained by using Vitek GPS-418 cards were compared with those obtained by the broth dilution method of the National Committee for Clinical Laboratory Standards (NCCLS) (approved standard M7-A4) and with those obtained by the agar screen method using bile esculin azide agar containing 6 microgram of vancomycin per ml. Although both the broth dilution and agar screen methods disclosed no discordance, Vitek GPS-418 cards yielded a very major error compared with the results obtained by the reference broth dilution method of the NCCLS. Vitek GPS-418 cards were therefore found to have considerable room for improvement for the accurate detection of vanB VRE strains.

Bacterial Proteins↗
PubMed2000

H(2)O(2) and ethanol act synergistically to gate ryanodine receptor/calcium-release channel.

We examined the effect of low concentrations of H(2)O(2) on the Ca(2+)-release channel/ryanodine receptor (RyR) to determine if H(2)O(2) plays a physiological role in skeletal muscle function. Sarcoplasmic reticulum vesicles from frog skeletal muscle and type 1 RyRs (RyR1) purified from rabbit skeletal muscle were incorporated into lipid bilayers. Channel activity of the frog RyR was not affected by application of 4.4 mM (0.02%) ethanol. Open probability (P(o)) of such ethanol-treated RyR channels was markedly increased on subsequent addition of 10 microM H(2)O(2). Increase of H(2)O(2) to 100 microM caused a further increase in channel activity. Application of 4.4 mM ethanol to 10 microM H(2)O(2)-treated RyRs activated channel activity. Exposure to 10 or 100 microM H(2)O(2) alone, however, failed to increase P(o). Synergistic action of ethanol and H(2)O(2) was also observed on the purified RyR1 channel, which was free from FK506 binding protein (FKBP12). H(2)O(2) at 100-500 microM had no effect on purified channel activity. Application of FKBP12 to the purified RyR1 drastically decreased channel activity but did not alter the effects of ethanol and H(2)O(2). These results suggest that H(2)O(2) may play a pathophysiological, but probably not a physiological, role by directly acting on skeletal muscle RyRs in the presence of ethanol.

Acetaldehyde↗
PubMed2000

Cardiac dysfunction and long-term prognosis in patients with nonobstructive hypertrophic cardiomyopathy and abnormal (123)I-15- (p-Iodophenyl)-3(R,S)-methylpentadecanoic acid myocardial scintigraphy.

To evaluate the relationship between myocardial scintigraphic abnormalities based on (123)I-radioiodinated 15-(p-iodophenyl)-3(R, S)-methylpentadecanoic acid (BMIPP) uptake and cardiac function and the relationship between these abnormalities and long-term prognosis in patients with hypertrophic cardiomyopathy (HCM), 27 patients with nonobstructive HCM underwent BMIPP myocardial scintigraphic study, echocardiography, and exercise radionuclide study. Based on the extent of BMIPP scintigraphic defects, the patients were divided into two groups: Group A (n = 19) patients had no or small defects, and group B (n = 8) patients had moderate to large defects. Cardiac events were recorded over an average period of 64 months. The left ventricular end-diastolic and end-systolic dimensions were significantly greater in group B than in group A. The fractional shortening in group B was less than in group A (p = 0.0002). The BMIPP score and fractional shortening at rest correlated significantly (p < 0.05). The BMIPP score and the change in ejection fraction between rest and peak exercise correlated significantly (p < 0.05). While only 1 cardiac event occurred in the 19 patients in group A during a mean follow-up period of 64 months, 6 cardiac events occurred in the 8 patients in group B. The 84-month event-free survival rate was 94.4% in group A and 14.6% in group B (p < 0.01). These results suggest that patients with HCM and moderate to large defects as assessed by BMIPP myocardial scintigraphy have decreased cardiac function and a poor prognosis.

Adult↗
PubMed2000

Susceptibility to lipopolysaccharide of cholestatic rat liver produced with bile duct ligation: assessments of the mitochondrial glutathione pool and the effects of N-acetylcysteine.

We investigated whether rats with obstructive jaundice produced with bile duct ligation for 2 weeks are more susceptible to the additional stress of lipopolysaccharide (LPS) administration than sham-operated rats and also examined the effects of N-acetylcysteine (NAC) on LPS stimulation in rats with bile duct ligation. The effects of LPS on the mitochondrial glutathione pool and on oxidative stress of polymorphonuclear leukocytes were investigated in cholestatic rats. Serum concentrations of alpha-glutathione S-transferase showed that lipopolysaccharide stimulation caused more severe hepatocellular injury in cholestatic rats than in sham-operated rats. In addition, concentrations of mitochondrial reduced and oxidized glutathione and hepatic adenosine triphosphate showed that LPS stimulation decreased mitochondrial function more in cholestatic rats than in sham-operated rats. Intraperitoneal administration of NAC for 2 weeks significantly improved mitochondrial function and decreased hepatocellular injury. However, the oxidative stress of polymorphonuclear leukocytes that had infiltrated hepatic tissue was increased by NAC. The present results indicate that the cholestatic liver is susceptible to the additional stress of LPS, that NAC suppresses the adverse effects of LPS in cholestatic livers, and that the oxidative stress of polymorphonuclear leukocytes is not significantly involved in mitochondrial dysfunction or hepatocellular injury in this model.

Acetylcysteine↗
PubMed2000

Bullous pemphigoid associated with silicosis.

Bullous pemphigoid (BP) has never before been reported to associate with silicosis, although there are numerous reports of silicosis accompanied by different autoimmune diseases, such as systemic sclerosis, systemic lupus erythematosus, dermatomyositis or rheumatoid arthritis. We report on a 63-year-old Japanese patient with silicosis who developed tensed bullae, erosions and macular pigmentation on the trunk and extremities. Indirect immunofluorescence revealed anti-basement-membrane-zone antibodies; immunoblotting analysis demonstrated that the patient's serum reacted with the 230-kD BP antigen in the epidermal extracts, as well as a recombinant protein of the NC16a domain of 180-kD BP antigen. Clinical symptoms improved after treatment with systemic steroids. To the best of our knowledge, this is the first reported case of BP associated with silicosis.

Humans↗
PubMed2000

Cystic schwannoma presenting as massive hemoptysis in an adult.

A 62-year-old man who presented with the chief complaint of hemoptysis is reported. A chest radiograph obtained on admission showed a huge cystic mass located at the posterior mediastinum. Prior to surgery, transarterial embolization was done because of continuous massive hemoptysis. An uneventful removal of the tumor was performed, and the pathological diagnosis was schwannoma. The hemoptysis was thought to have been caused by changes in the cystic formation in combination with inflammation which extended to the lung.

Biopsy, Needle↗
PubMed2000

Decreased matrix metalloproteinase activity in the kidneys of hereditary nephrotic mice (ICGN strain).

Abnormalities of extracellular matrix (ECM) metabolism, i.e., overproduction and/or inhibition of ECM breakdown, may contribute to progression of fibrotic degeneration in the kidney. Earlier studies revealed that major ECM components, type I, III, and IV collagens, etc., were accumulated in glomeruli and tubulointerstitium in kidneys of Institute of Cancer Research (ICR) derived glomerulonephritis (ICGN) mice which are a novel inbred strain of mice with a hereditary nephrotic syndrome of unknown etiology and are considered to be a good model of human idiopathic nephrotic syndrome. In the present study, we compared the activities of matrix metalloproteinases (MMPs), a family of enzymes that degrade ECM components, in the kidneys of aged ICGN mice and age-matched ICR mice as normal controls. We biochemically measured interstitial collagenase (MMP-1), gelatinase (MMP-2 and MMP-9), and stromelysin (MMP-3) activities in the kidney tissues. Lower activities of MMP-1 and MMP-2 and MMP-9 were demonstrated in the kidneys of ICGN mice as compared with those of ICR mice, but there were no significant differences in the MMP-3 activities between these strains. These results show that decreased MMP activities cause abnormal accumulation of ECM in ICGN mouse kidneys.

Aging↗
PubMed2000

A rapid and simple photometric assay for quantification of eosinophil chemotaxis.

Various methods have been devised to assay eosinophil chemotaxis. In this review, we introduced a rapid and sensitive eosinophil chemotactic assay system based on eosinophil peroxidase (EPO) determination. Eosinophils were semipurified by dextran sedimentation followed by Percoll gradient centrifugation. Eosinophil migration was measured by the Boyden blind-well chamber technique using a 96-well multiwell chamber and polycarbonate membrane filter. The number of migrated eosinophils was assessed by determination of the EPO activity of drop-off cells, and photometric measurement was performed with a microtiter plate reader. The contribution of neutrophil peroxidase to the assay is negligible, and the assay is sensitive enough to detect 200 eosinophils. The method is both less tedious and less laborious than conventional manual methods, and it allows a large number of samples to be analyzed within 4 h. When eosinophils were exposed to 15 chemokines and their migration was assayed using this method, we found that only CC chemokine receptor 3 ligands, such as eotaxin, induced significant eosinophil migration.

Chemotaxis, Leukocyte↗
PubMed2000

Regulation of human eotaxin generation by Th1-/Th2-derived cytokines.

BACKGROUND: Accumulating evidence indicates that eotaxin is the primary mediator of tissue eosinophilia. In the present study, we analyzed the mechanisms of eotaxin generation by Th1-/Th2-derived cytokines in vitro. METHODS: Human dermal fibroblasts, human umbilical vein endothelial cells and A549 human bronchial epithelial cell line cells were stimulated with TNF-alpha, IL-4, IFN-gamma or TNF-alpha in combination with IL-4 or IFN-gamma and the amount of eotaxin production was analyzed. RESULTS: Fibroblasts produced nanogram/milliliter quantities of eotaxin. Proinflammatory cytokine TNF-alpha and Th2-type cytokine IL-4 each induced eotaxin production, and combination of them caused a marked synergistic increase in that production. On the other hand, Th1-type cytokine IFN-gamma inhibited eotaxin generation at the protein/mRNA levels. CONCLUSION: The Th2-derived cytokine upregulated while the Th1-derived cytokine inhibited eotaxin production by fibroblasts. In view of the Th1/Th2 paradigm, these results indicate that (1) eotaxin regulates eosinophil accumulation in the Th2-dominant state such as allergic disease, and (2) direct suppression of eotaxin production by IFN-gamma is one of the major mechanisms by which IFN-gamma suppresses eosinophilic inflammation.

Cell Line↗