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Biomedical subjects

H Yamaguchi

Publications and source records attributed to H Yamaguchi.

At least 775 records · Page 43Linked to original sources

A novel model of cutaneous candidiasis produced in prednisolone-treated guinea-pigs.

In an attempt to develop an animal model of cutaneous candidiasis useful for the pre-clinical evaluation of antifungal drugs, experimental cutaneous Candida albicans infections were produced in mature and immature guinea-pigs treated with prednisolone. The morbidity of this model in terms of the extent and the duration of the superficial infection was compared with that of two other reported models: those produced by alloxan treatment, or the use of occlusive dressings. Infected animals were also included which received neither of these treatments. The Candida infection continued steadily for 14 days or more in both mature and immature animal groups treated subcutaneously with prednisolone and appeared to be more suitable than that produced with alloxan treatment or under occlusive dressings. In prednisolone-induced infection, most of the micro-organisms were confined to the epidermis and there was no evidence of their dermal penetration during the 14 day experimental period. In view of these facts, we attempted a more quantitative method by counting viable Candida in order to evaluate antimycotics in a shorter therapy period during which animals would receive less exposure to the vehicle. These findings appear to indicate that the experimental model of cutaneous C. albicans infection produced in prednisolone-treated mature and immature guinea-pigs would be useful for studies on the therapeutic efficacy of antifungal agents against cutaneous candidiasis.

Administration, Topical↗

Inhibition of vasoactive amine induced contractions of vascular smooth muscle by hydrogen peroxide in rabbit aorta.

OBJECTIVE: The aims were to investigate the effects of H2O2 on arterial contractions induced by vasoactive amine agonists and a high concentration of potassium ions (high K+) in vitro and to explore the possible underlying mechanism(s) involved. METHODS: Isometric tension of rabbit isolated aortic strips was measured and the effects of pretreatment with H2O2 on contractions induced by phenylephrine and high K+ were compared. The effects of H2O2 on precontracted strips were determined in the presence and absence of the aortic endothelium and compared with those of acetylcholine. RESULTS: The tension developed in response to an agonist was expressed as a percentage of the contraction induced by high K+ (64.7 mM) superfusion. Pretreatment with 300 microM H2O2 reduced the mean phenylephrine (0.3 microM) induced contraction from 96.2(SEM 1.4) to 61.8(2.8)%; the effect was stable and reversed by washing out the H2O2. Hydrogen peroxide relaxed phenylphrine precontracted strips with and without endothelium but it showed no relaxant effect when the strips were precontracted by high K+, whereas acetylcholine (1 microM) induced transient relaxation of high K+ precontracted strips by 27.8(2.9)%. The relaxant effect of H2O2 was not affected by pretreatment with indomethacin (a cyclo-oxygenase inhibitor), desferrioxamine (a hydroxyl radical scavenger), or diphenylphenylenediamine (a lipophilic antioxidant). CONCLUSIONS: H2O2 inhibits vasoactive amine induced contractions of the vascular smooth muscle of rabbit aorta in vitro without affecting voltage dependent Ca2+ influx or contractile machinery. The mechanism responsible for its inhibitory effects may be related to impairments of the cellular signalling reactions initiated by the agonists.

Acetylcholine↗

Blood pressure responses in Japanese and Swedish children in the supine and standing position.

We investigated the cardiovascular responses to active standing in Swedish and Japanese pre-pubertal children using non-invasive continuous beat-to-beat finger blood pressure (BP) monitoring. Seventy-eight Swedish (7-12 years) and 53 Japanese children (6-12 years) were examined. There were no significant differences in body weight or height between the two groups (total group). Finger blood pressure and heart rate were continuously recorded in the supine position and during standing. Supine BP was significantly higher in Swedish compared to Japanese children (115/65 vs 98/50 mmHg, P < 0.001), and Swedish children showed a significantly larger initial BP drop upon rising (-28/15 vs - 14/ -10 mmHg, P < 0.05) and a larger increment of heart rate (39 +/- 10 vs 29 +/- 8 beats. min-1, P < 0.05). There were, however, no differences in the blood pressure and heart rate changes in the following steady state period (2-3 min) between the two groups. These results suggest that Swedish pre-pubertal children have a higher basal blood pressure and enhanced cardiovascular autonomic responses, such as pronounced baroreflex receptor sensitivity and vasoconstrictor mechanisms. These differences in the two cohorts were not related to body dimensions or degree of maturation, indicating that autonomic functions in the cardiovascular system largely depend on genetic factors and environmental variables.

Anthropometry↗

Cardiac myxoma with Gamna-Gandy bodies: case report with MR imaging.

We describe a patient with a left atrial tumor that showed very unusual magnetic resonance (MR) imaging features. Postsurgical histologic examination showed characteristics of myxoma, and Gamna-Gandy bodies were found in the tumor. We believe that the unusual MR appearance was caused by the hemosiderin in the Gamna-Gandy bodies.

Aged↗

Role of oxygen-derived free radicals in hemorrhagic pancreatitis induced by stress and cerulein in rats.

The role of oxygen-derived free radicals in the pathogenesis of acute pancreatitis was studied in a new model of acute hemorrhagic pancreatitis and cerulein-induced edematous pancreatitis in rats. Hemorrhagic pancreatitis was produced by administering two intraperitoneal doses of cerulein [40 micrograms/kg body weight (BW)] at 1-h intervals following water immersion stress applied for 5 h. Edematous pancreatitis was induced by injecting cerulein as described but without water immersion. Five hours after the first injection of cerulein, pancreatic edema and elevation of serum amylase level were more marked in the animals with hemorrhagic than with edematous pancreatitis. Five hours after the first injection of cerulein, marked hemorrhage and venous dilatation were observed only in those with hemorrhagic pancreatitis. Local pancreatic blood flow decreased to approximately 60% of control values in the animals with edematous pancreatitis, and to approximately 30% of control values in those with hemorrhagic pancreatitis. To evaluate the involvement of oxygen radicals, some rats received three intraperitoneal injections of superoxide dismutase (SOD 10,700 U/kg BW) and catalase (132,000 U/kg BW) beginning 15 min before the first injection of cerulein and repeated at 1-h intervals. No significant effect of free radical scavengers was observed on the edematous pancreatitis. However, in hemorrhagic pancreatitis, treatment with SOD and catalase completely suppressed the hemorrhage and venous dilatation of the pancreas, significantly reduced the pancreatic wet weight and the serum amylase level, and reduced the histologic alterations. However, after treatment with SOD and catalase, no differences were observed in local pancreatic blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Amylases↗

Ultrastructural study of the effects of stress on the pancreas in rats.

We studied morphologic changes in a rat model of acute hemorrhagic pancreatitis in order to investigate the mechanism by which water immersion stress injures the pancreas. Acute hemorrhagic pancreatitis was induced by two intraperitoneal injections of 40 micrograms/kg body weight of caerulein at 1-h intervals under water immersion stress for 5 h at 23 degrees C. Light microscopy showed interstitial edema with inflammatory cell infiltration, degeneration and necrosis of acinar cells, and bleeding. Electron microscopy showed large autophagic vacuoles, decreased zymogen granules, and dilated rough endoplasmic reticulum in acinar cells. Basolateral exocytosis of large vacuoles and phagocytosis of the degenerated acinar cells were observed. In addition, microvascular damage, including the destruction of the capillary endothelial cells, capillary thrombosis, and the extravasation of blood cells, was seen. In contrast, in a pancreatitis model induced by caerulein injection alone, there was no bleeding, no remarkable vascular change, and no thrombosis. Degeneration and necrosis of acinar cells were less severe. In the pancreas under stress alone, microvascular damage and degeneration of acinar cells were observed. These findings demonstrate that stress injures the pancreas and worsens the pancreatitis by causing microcirculatory disturbances, such as vascular damage, thrombosis, increased vascular permeability, and bleeding. These results suggest that chemical mediators, such as free radicals and platelet-activating factor (PAF), which are produced by vascular damage and thrombosis, may accelerate the activation of zymogen proteases in acinar cells in caerulein-induced pancreatitis, leading to hemorrhagic pancreatitis.

Acute Disease↗

Detection of a wide range of medically important fungi by the polymerase chain reaction.

A polymerase chain reaction (PCR) method was developed that was capable of detecting a wide range of medically important fungi from clinical specimens. The primer pair was designed in conserved sequences of 18S-ribosomal RNA genes shared by most fungi. The lower limit of detection of this PCR technique was 1 pg of Candida albicans genomic DNA by ethidium bromide staining and 100 fg after Southern analysis. A 687-bp product was amplified successfully by PCR from all 78 strains of 25 medically important fungal species studies, including Candida spp., Hansenula spp., Saccharomyces cerevisiae, Cryptococcus neoformans, Trichosporon beigelii, Malassezia furfur, Pneumocystis carinii, Aspergillus spp., and Penicillium spp., but not from any strains of Mucor spp., Escherichia coli, or methicillin-resistant Staphylococcus aureus (MRSA), calf thymus or human placenta. This specificity was subsequently confirmed by Southern analysis. PCR analysis of blood specimens collected from mice systemically infected with C. albicans and clinical samples including blood, cerebrospinal fluid and sputum appeared to be a more sensitive diagnostic method for invasive fungal infections than a conventional blood culture technique.

Animals↗

Inhibition of Candida albicans growth by murine peritoneal neutrophils and augmentation of the inhibitory activity by bacterial lipopolysaccharide and cytokines.

Anti-Candida activity of murine neutrophils and its regulation by immunomodulators were studied in vitro. Murine neutrophils which were prepared from peritoneal-exudated cells inhibited the growth of Candida albicans at an effector: target (E/T) ratio of 30/1 or above. This anti-Candida activity of neutrophils was augmented by lipopolysaccharide from Escherichia coli, murine tumor necrosis factor (TNF), murine interferon-gamma (IFN-gamma) and murine granulocyte macrophage colony-stimulating factor (GM-CSF) but not by granulocyte colony-stimulating factor (G-CSF) added to the incubation medium. Greater extent of augmentation was obtained when TNF plus GM-CSF or INF-gamma plus GM-CSF were used in combination. These results indicate that anti-Candida activity of murine neutrophils is regulated similarly to that of the human neutrophils reported previously. Therefore murine peritoneal neutrophils can be used as a favorable substitute for human neutrophils in studies on protective machinery against C. albicans infection.

Animals↗

A rapid colorimetric assay for determination of leukocyte-mediated inhibition of mycelial growth of Candida albicans.

A staining method with crystal violet (CV) was demonstrated to be useful for a simple, quick and objective assessment of in vitro growth inhibitory activity of leukocytes against Candida albicans cells. Candida cells incubated with murine neutrophils or macrophages for 14 hr in microwells were stained with CV and, after washing with 0.25% sodium dodecyl sulfate (SDS), treated with isopropanol containing HCl (0.04 N) to extract Candida cell-bound CV. Then the absorbance at 590 nm of the isopropanol extract was photometrically measured. The results showed that the photometrical absorbance was proportional to the amount of 3H-glucose taken up by C. albicans cells, which reflected the number of viable Candida cells.

Animals↗

Detection and characterization of antibodies to bacterial heat-shock protein 60 in sera of patients with primary biliary cirrhosis.

The enzyme-linked immunosorbent assay (ELISA) with bacterial heat-shock protein 60 (HSP60) purified from Yersinia enterocolitica (Ye) revealed that the antibodies directed against YeHSP60 existed in sera of patients with primary biliary cirrhosis (PBC). To characterize the epitope specificity of the antibodies in patients, the epitope mapping of HSP60 by means of the antibodies was performed. The results have suggested that the epitope recognized with anti-HSP60 antibodies in PBC relates to the amino acid sequence of YeHSP60 molecule as follows: DLGQAKRVVINKDTTIIIDGVGDEAAIQGRLAQIRQQIEEATSDYDKEK.

Amino Acid Sequence↗

Characterization of immunological activity of a low toxicity antitumor lipopolysaccharide from Bordetella pertussis.

Immunological properties of a low toxicity lipopolysaccharide (BP-LPS) extracted from Bordetella pertussis (Tohama strain) which was reported to have high antitumor activity against murine tumors were examined and compared with those of LPS extracted from other enterobacteria. The activation or stimulation of murine macrophages and lymphocytes by these LPS, including TNF induction, was found to be similar. However, BP-LPS was clearly less active in its stimulation of murine and human neutrophils as estimated by neutrophil-adherence assay and by their TNF production than E. coli LPS. Furthermore, BP-LPS also suppressed the activation of human neutrophils by Escherichia coli LPS. A comparative study with 7 LPS preparations indicated that their toxicity in terms of animal body weight loss correlated with their ability to induce human neutrophil adherence. The inability of BP-LPS to activate neutrophils may thus have some bearing on its low toxicity.

Animals↗

Suppression of anti-Candida activity of murine and human neutrophils by glucocorticoids.

Effects of glucocorticoid (GC) compounds on inhibitory activity of neutrophils to mycelial growth of Candida albicans were examined by in vitro crystal violet staining method with 14 hr coculture. Both GC hormones (hydrocortisone > or = 6 x 10(-7) M and corticosterone > or = 10(-6)M) and anti-inflammatory GC agents (prednisolone > or = 10(-7) M and dexamethasone > or = 10(-8) M) significantly suppressed anti-Candida activity of murine casein-induced neutrophils. Anti-Candida activity of human neutrophils prepared from peripheral blood was also suppressed by hydrocortisone (> or = 6 x 10(-7) M). These GC compounds did not affect the Candida growth in the absence of neutrophils. Steroidal compounds without anti-inflammatory activity, cholesterol, cholic acid, aldosterone did not suppress neutrophil activity. These results suggest that GCs at their physiological or clinical concentration may suppress anti-Candida activity of neutrophils in vivo.

Aldosterone↗

Atopic asthma caused by Candida albicans acid protease: case reports.

Two cases of atopic asthma caused by acid protease produced by Candida albicans are reported. Both patients had high levels of serum IgE antibodies against the acid protease and showed positive conjunctival and immediate bronchial responses when challenged with the protease. Significant histamine release was detected in both patients when their peripheral leukocytes were challenged with the protease antigen. These findings clearly showed that C. albicans acid protease is the causative allergen of atopic asthma.

Allergens↗

Intra-His bundle block corresponds with interruption of the branching portion of the His bundle.

We compared His-bundle electrograms with pathological findings of the atrioventricular conduction system in four patients with complete atrioventricular intra-His block with narrow QRS complexes on ECG. Split His electrograms were recorded at the time of electrophysiological study. The patients died from noncardiac causes at 10 days, 1 year, 4 years, and 9 years, respectively, after the pacemaker implantation. Serial sections through the atrioventricular conduction system revealed strictly localized more than 50% reduction of conducting cells replaced by fibrosis at the branching portion of His bundle. The proximal portions of the bundle branches also exhibited decrease of the conducting cells showing a rough positive relation with the patient's age. Therefore, we considered that the H1 spikes seen on His-bundle electrograms originated from the penetrating portion of His, which was virtually intact in our cases, and that the H2 spikes originated from the right side of the distal branching portion of His.

Aged↗