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Biomedical subjects

H Higuchi

Publications and source records attributed to H Higuchi.

At least 127 records · Page 7Linked to original sources
PubMed1997

Dopamine releasing response in rat striatum to single and repeated electroconvulsive shock treatment.

1. The effect of electroconvulsive shock (ECS) on extracellular concentration of dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) was examined with the use of in vivo microdialysis in rat striatum. 2. Extracellular concentration of DA was markedly increased up to 183% after single ECS, and that of DOPAC, HVA and 5-HIAA was also significantly increased. The increase after the eighth ECS was attenuated compared to their increase soon after the first ECS. After repeated ECS, baseline concentration of DOPAC, HVA and 5-HIAA was significantly increased, and baseline DA concentration tended to increase. 3. These results suggested that single and repeated ECS activated metabolism of DA and 5-hydroxytryptamine in rat striatum. Activated metabolism of DA may be responsible for the clinical effect of electroconvulsive therapy for parkinsonism.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1997

Imaging and nano-manipulation of single biomolecules.

We have developed a new technique for imaging single fluorescent dye molecules by refining epifluorescence and total internal reflection fluorescence microscopies. In contrast to previously reported single fluorescent molecule imaging methods, in which specimens were immobilized on an air-dried surface, our method enables video-rate imaging of single molecules in aqueous solution. This approach enabled us to directly image the processive movement of individual fluorescently labeled kinesin molecules along a microtubule. This method was also used to visualize individual ATP turnover reactions of single myosin molecules. The method can be combined with molecular manipulation using an optical trap. A single kinesin molecule attached to a polystyrene bead was brought into contact with a microtubule adsorbed onto the glass surface. The lifetime of bound Cy3-nucleotide in the absence or presence of the microtubule was 10 s or 0.08 s, respectively, showing that ATPase activity of the kinesin is strongly activated by microtubules. As the present system is equipped with a nanometer sensor, elemental steps of a single kinesin molecule can also be measured. By simultaneously measuring the individual ATP turnovers and elementary mechanical events of a single kinesin molecule, we will be able to obtain a clear answer to the fundamental problem of how the mechanical events are coupled to the ATPase reaction.

Adenosine Triphosphate↗
PubMed1997

CD18/ICAM-1-dependent nitric oxide production of Kupffer cells as a cause of mitochondrial dysfunction in hepatoma cells: influence of chronic alcohol feeding.

The present study was designed to monitor the process for hepatoma cell injury induced by Kupffer cells. The non-activated Kupffer cells isolated from male Wistar rats reduced the mitochondrial membrane potential in the cocultured AH70 cells, which was indicated by the decreased rhodamine 123 (Rh123) fluorescence. Increased level of nitrite and nitrate in the medium and induction of iNOS in Kupffer cells were observed after coculture with AH70 cells. Incubation with either NG-monomethyl-L-arginine or aminoguanidine attenuated the increased nitric oxide (NO) production of Kupffer cells and the decreased Rh123 fluorescence of AH70 cells. Fluo-3, a calcium-sensitive probe, fluorescence in Kupffer cells increased after coculture with AH70 cells. Addition of TMB-8, a calcium inhibitor, or monoclonal antibody directed against ICAM-1 or CD18 prevented the increases in fluo-3 fluorescence and NO production of Kupffer cells and Kupffer cell-induced mitochondrial dysfunction in AH70 cells, suggesting the involvement of calcium mobilization and CD18/ICAM-1. It is therefore suggested that the Kupffer cell-mediated mitochondrial dysfunction of hepatoma cells largely depends on NO production by iNOS, and that the NO production by Kupffer cells is triggered by CD18/ICAM-1-dependent interaction with hepatoma cells and subsequent calcium mobilization. In other series of experiments, male Wistar rats fed ethanol for 4 weeks were used. The NO production and calcium mobilization of Kupffer cells and reduction of the mitochondrial membrane potential in cocultured hepatoma cells were diminished in the case of Kupffer cells isolated from chronically ethanol-fed rats, while CD18 and ICAM-1 expression was still observed. Thus, the present study further suggests that NO-dependent anti-hepatoma cell activity of Kupffer cells is suppressed in chronically ethanol-fed animals.

Alcoholism↗
PubMed1997

Increased nitric oxide production and inducible nitric oxide synthase activity in colonic mucosa of patients with active ulcerative colitis and Crohn's disease.

It is postulated that an enhanced production of nitric oxide by inflamed intestine plays a role in the pathophysiology of active inflammatory bowel disease. In this study, systemic NOx concentrations and colonic nitric oxide synthase activity were determined in patients with ulcerative colitis or Crohn's disease. The relationship between these two parameters and disease activity, as well as differences in nitric oxide synthase activity between ulcerative colitis and Crohn's disease, were areas of specific focus. Patients with active ulcerative colitis and Crohn's disease had significantly elevated plasma NOx concentrations; a positive correlation was found between NOx values and inducible nitric oxide synthase activities in the active mucosa of these patients. In active ulcerative colitis, levels of inducible nitric oxide synthase were significantly elevated in both normal and inflamed mucosa, although inducible nitric oxide synthase activity was higher in the latter. These colonic inducible nitric oxide synthase activities correlated well with the results of endoscopic and histologic grading of inflammation. There was no increase in constitutive nitric oxide synthase activity in patients with active ulcerative colitis. However, constitutive nitric oxide synthase activity was significantly increased in the inflamed mucosa in patients with Crohn's disease. In Crohn's disease, elevated inducible nitric oxide synthase activity was found in both normal and inflamed mucosa, with no significant difference between the tissues. Such differences in nitric oxide production in the colonic mucosa possibly reflect the significant differences in the pathophysiology and characteristic clinical features between ulcerative colitis and Crohn's disease.

Adult↗
PubMed1997

Enhanced lymphocyte interaction in postcapillary venules of Peyer's patches during fat absorption in rats.

BACKGROUND & AIMS: Although dietary fat is known to modulate immune functions, there is a paucity of data concerning the effects of fat absorption on migration of lymphocytes in intestinal lymphoid tissue. The objective of this study was to assess the influence of fat absorption on T-lymphocyte migration in Peyer's patches. METHODS: T lymphocytes collected from rat intestinal lymph were labeled with carboxyfluorescein diacetate succinimidyl ester and injected into the jugular vein of recipient rats. Olive oil or octanoic acid was placed into the duodenum, and Peyer's patch microcirculation was observed by intravital fluorescence microscopy. RESULTS: Rolling and adherence of lymphocytes in postcapillary venules were noted in both fasted and fed rats. However, lymphocyte adherence was significantly greater in olive oil-fed rats than in fasted rats. Olive oil also significantly increased the transendothelial migration of T lymphocytes. Octanoic acid stimulated lymphocyte rolling but did not affect lymphocyte adherence. Olive oil enhanced the expression of both alpha4-integrin and L-selectin on lymphocytes, whereas octanoic acid only increased the expression of L-selectin. CONCLUSIONS: Lymphocyte rolling and adherence are enhanced by olive oil feeding, possibly through an interaction between activated adhesion molecules on lymphocytes and counter-receptors on endothelial cells.

Animals↗
PubMed1997

Oxidative stress-mediated apoptosis of hepatocytes exposed to acute ethanol intoxication.

The present study was designed to investigate whether acute ethanol intoxication increases the production of active oxidants, and subsequently promotes apoptosis of hepatocytes. Hepatocytes were isolated from male Wistar rats, and cultured in the presence or absence of ethanol. The fluorescence in situ nick end labeling method and an enzyme-linked immunosorbent assay (ELISA) system to quantify fragmented DNA were used to estimate apoptotic change in hepatocytes. Nuclear morphological alterations and membrane barrier dysfunction of hepatocytes were assessed by staining with Hoechst 33342 and propidium iodide (PI). Intracellular glutathione level was determined as the fluorescence of monochlorobimane (MCLB), which forms conjugate with glutathione to become fluorescent. Ethanol (100 mmol/L) increased the amount of fragmented DNA and the number of apoptotic hepatocytes in vivo as well as in vitro. These ethanol-induced alterations in hepatocytes were attenuated by simultaneous incubation with either 4-methylpyrazole, an inhibitor of alcohol dehydrogenase, or dimethylthiourea, an intracellular oxidant scavenger. Diethyl maleic acid (DMA), a glutathione depletor, enhanced the induction of apoptotic change, and decreased membrane barrier function in ethanol-treated hepatocytes, whereas ethanol per se did not increase the number of PI-positive hepatocytes. Furthermore, combination of ethanol and DMA but not ethanol alone decreased the hepatocyte MCLB fluorescence. Taken together, the present study suggests that active oxidants produced during ethanol metabolism mediate fragmentation of DNA in hepatocytes, and that intracellular antioxidants such as glutathione play a critical role in the cytoprotective mechanisms of hepatocyte against lethal cell death, ie, apoptosis, induced by ethanol.

Animals↗
PubMed1997

Fc receptor-mediated phagocytosis, superoxide production and calcium signaling of beta 2 integrin-deficient bovine neutrophils.

Fc receptor for immunoglobulin G-mediated phagocytosis, superoxide production and intracellular calcium ([Ca2+]i) signaling of complement receptor type 3 (CR3)-deficient neutrophils from a heifer with leukocyte adhesion deficiency (BLAD) were compared to those of control heifers. The mean phagocytic activity of IgG-coated yeasts and aggregated bovine IgG (Agg-IgG)-induced superoxide production of CR3-deficient neutrophils were 10% and 77.9%, respectively, of those of control neutrophils. The [Ca2+]i signals in CR3-deficient neutrophils stimulated with Agg-IgG or concanavalin A were different with mean peak [Ca2+]i concentrations of 78% and 41.9%, respectively, of those of control neutrophils. These findings suggest that Fc receptor-mediated neutrophil functions are closely dependent on the presence of CR3 (CD11b/CD18) on the neutrophil cell surfaces.

Animals↗
PubMed1997

Minimum alveolar concentration of sevoflurane for tracheal extubation in children.

BACKGROUND: One advantage of tracheal extubation during deep anaesthesia is that respiratory complications are reduced. Sevoflurane is a suitable anaesthetic agent for children. This study was conducted to determine the minimum alveolar concentration of sevoflurane required to prevent cough or movement during and after tracheal extubation (MACextubation). METHODS: We studied 30 nonpremedicated children, aged 2-10 yr, undergoing plastic surgery. They were allocated randomly to five groups (end-tidal sevoflurane concentrations: 2.0, 2.5, 3.0, 3.5, 4.0%). After surgery, 60% nitrous oxide was discontinued and the target concentration of sevoflurane was maintained for at least 10 min in 100% oxygen, then the trachea was extubated to determine MACextubation. Logistic regression was used to estimate MACextubation of sevoflurane. RESULTS: MACextubation was 2.3 (0.2; standard error)% (95% confidence limits: 1.2% and 2.7%). CONCLUSIONS: Tracheal extubation in 50% of anaesthetized children age 2-10 yr may be accomplished without coughing or moving at 2.3% end-tidal concentration of sevoflurane.

Anesthetics, Inhalation↗
PubMed1997

Recurrent paroxysmal episodes characterized by perceptual alteration in three schizophrenic patients on neuroleptic medication.

A suddenly occurring episode characterized by perceptual alteration (SEPA), mainly of visual and/or auditory modalities, which repeatedly occurred in three schizophrenic patients on long-term neuroleptic medication, is described. Perceptual alteration showed some distinct features that were different from acute symptoms of schizophrenia, and was accompanied by mood changes such as severe anxiety and agitation and, in one of the patients, also by extrapyramidal symptoms. Perceptual alteration, as well as mood changes and extrapyramidal symptoms, responded well to an anticholinergic drug, biperiden. Recent studies have shown that SEPA occurred not only in schizophrenic patients but also in patients on long-term neuroleptic medication for treating other mental disorders. These findings suggest that SEPA is associated with dopaminergic hypoactivity in the brain, which is induced by long-term neuroleptic medication.

Adult↗
PubMed1997

Vasoactive intestinal peptide modulates T lymphocyte migration in Peyer's patches of rat small intestine.

Although vasoactive intestinal peptide (VIP) has been postulated to function in modulation of T cell trafficking, the exact mechanism has not been elucidated in vivo. In the present study, the effects of VIP on T lymphocyte migration were examined in rat Peyer's patches. T lymphocytes collected from intestinal lymph of rats were labeled with carboxyfluorescein diacetate succinimidyl ester and injected into the jugular vein. Peyer's patches of the recipient rats were observed with intravital fluorescence microscopy. In vivo intra-arterial infusion of or in vitro incubation with VIP did not affect the initial lymphocyte interaction with postcapillary venules of Peyer's patches. However, these treatments with VIP significantly inhibited transendothelial migration and also significantly blocked the interstitial migration of T cells and inhibited their subsequent appearance in the interfollicular lymphatics. Treatment with adenosine 3',5'-cyclic monophosphate (cAMP)-inducing agents resulted in similar inhibitory effect on T lymphocyte migration in Peyer's patches. In conclusion, VIP has significant inhibitory effects on T lymphocyte migration in Peyer's patches, possibly mediated by elevation of the intracellular cAMP concentrations.

Animals↗
PubMed1997

Leukocyte emigration in normal calves and calves with leukocyte adhesion deficiency.

The emigration of leukocytes from calves with beta 2 integrin deficiency (BLAD) into bronchoalveolar spaces and scraped tissues was compared to that of normal calves. Polymorphonuclear neutrophils were found in bronchoalveolar lavage fluid from BLAD-affected calves showing chronic pneumonia. The neutrophils were complement receptor type 3 (CR3)-negative when characterized by flow cytometric analysis using anti-CD18 monoclonal antibody. Chemiluminescent response mediated by CR3 in neutrophils isolated from bronchoalveolar lavage fluid from BLAD-calves showed similar findings obtained from CR3-deficient neutrophils. Neutrophils from normal calves migrated into scraped tissue which was prepared in an upper gluteal surface area, whereas few leukocytes from calves with BLAD migrated to the scraped tissue, evaluated by skin window (Rebuck) method. These findings confirmed the extravasation of CR3-deficient leukocytes into bronchoalveolar lumen in BLAD calves, and demonstrated in vivo characteristics of extravasating property of normal and CR3-deficient neutrophils into scraped tissues.

Animals↗
PubMed1997

Relationship between age-dependent changes of bovine neutrophil functions and their intracellular Ca2+ concentrations.

Neutrophil functions and intracellular Ca2+ concentrations ([Ca2+]i) were evaluated in 15 Holstein cattle divided into the following 3 groups: 5 neonatal calves less than 1 week old (group 1), 5 young calves 2 to 4 weeks old (group 2) and 5 cows 2 to 3 years old (group 3). The ability of neutrophils to phagocytose Candida albicans (C. albicans) was significantly higher (p < 0.05) in neonatal and young calves than in cows, whereas the phagocytosis by neutrophils of bovine IgG-coated yeasts (IgG-yeasts) was significantly lower (p < 0.05) in neonatal and young calves than that in cows. The killing activity by neutrophils of C. albicans in neonatal and young calves was significantly lower (p < 0.05) than that in cows. Luminol dependent chemiluminescent (LDCL) responses stimulated with opsonized zymosan (OPZ), heat-aggregated IgG (H-agg.IgG) and phorbol myristate acetate (PMA) were apparently lower in neonatal and young calves than in cows. No clearly different expressions of complement receptor type 3 (CR3) on neutrophils were observed among the 3 groups of cattle, although the values due to the binding of FITC-anti-bovine IgG to neutrophils in neonatal and young calves were lower than those in group 3. The OPZ-induced [Ca2+]i of neutrophils in neonatal and young calves were significantly higher (p < 0.05) than those in cows, but they were lower in neonatal and young calves when stimulated with H-agg.IgG. These results indicate that CR3- and FcR-mediated phagocytic and killing activities of neutrophils in neonatal and young calves are different from those in cows. These phenomena may be associated with age-dependent changes in [Ca2+]i.

Aging↗
PubMed1997

Relationship between the chemiluminescent response of bovine neutrophils and changes in intracellular free calcium concentration.

The relationship between luminol dependent chemiluminescent (LDCL) response and changes in intracellular free Ca2+ concentrations in the bovine neutrophils was evaluated. LDCL responses and changes in intracellular Ca2+ concentrations of neutrophils were clearly detected by the stimulation with opsonized zymosan (OPZ), concanavalin A(ConA), heat-aggregated IgG (H-agg.IgG) and phorbol myristate acetate (PMA). Patterns of LDCL responses and intracellular Ca2+ of neutrophils showed characteristic features for each stimulant. PMA was a weak stimulant of the intracellular Ca2+ concentration, whereas it was a strong stimulant of LDCL response. Con A strongly stimulated an increase in the intracellular Ca2+ concentration, but was a weak stimulant of LDCL response. LDCL response of intracellular Ca(2+)-depleted neutrophils treated with ionomycin, stimulated with each stimulant was inhibited markedly without extracellular Ca2+. The sustained phase of intracellular Ca2+ concentrations stimulated with OPZ was inhibited significantly (P < 0.05) by the preincubation with anti-CD18 antibody, whereas the transient phase of intracellular Ca2+ concentrations was not inhibited. These results indicate that LDCL response is regulated at least in part by the elevation of the intracellular Ca2+, and a rise in intracellular Ca2+ concentration, which may be mediated by specific receptors appears to be essential in the LDCL response of bovine neutrophils.

Animals↗
PubMed1996

Increased nitric oxide synthase activity as a cause of mitochondrial dysfunction in rat hepatocytes: roles for tumor necrosis factor alpha.

Kupffer cells have been implicated in playing an important role in the pathogenesis of endotoxemia-associated liver injury. The present study was designed to investigate whether Kupffer cell-derived mediators alter the mitochondrial oxidative phosphorylation of hepatocytes in the endotoxemic condition. Liver cells were isolated from male Wistar rats. Oxidative phosphorylation was monitored as the fluorescence of rhodamine 123 (Rh123), which is the fluorescent cationic dye used to indicate mitochondrial energy synthesis. Two hours after coculture of hepatocytes with lipopolysaccharide (LPS)-pretreated Kupffer cells, a marked decrease in hepatocyte rhodamine 123 fluorescence was observed. The hepatocyte mitochondrial dysfunction was attenuated by the addition of either N(G)-monomethyl-L-arginine (L-NMMA), an inhibitor of nitric oxide (NO) synthesis, or aminoguanidine, an inducible-type of NO synthase inhibitor, to the culture medium of cocultures, to the pretreatment of LPS-activated Kupffer cells with antisense oligodeoxynucleotides against iNOS messenger RNA (mRNA), or to tumor necrosis factor alpha (TNF-alpha) mRNA. Four hours after the coculture, hepatocyte Rh123 fluorescence further decreased, and an iNOS induction as well as an increased NO production were observed in hepatocytes that were cocultured with LPS-pretreated Kupffer cells. The membrane barrier dysfunction of hepatocytes, indicated by propidium iodide staining, was also induced by a 4-hour coculture with LPS-pretreated Kupffer cells. These late-phase changes were inhibited either by the pretreatment of hepatocytes with antisense oligodeoxynucleotides against iNOS mRNA or by treatments that are effective in the early phase (within 2 hours). Incubation with recombinant rat TNF-alpha decreased hepatocyte Rh123 fluorescence within 2 hours. Thus, the present study suggests that NO and TNF-alpha released from LPS-pretreated Kupffer cells directly inhibit the hepatocyte mitochondrial function in the early phase, and then NO synthesized by TNF-alpha-induced hepatocyte iNOS causes lethal hepatocyte injury, characterized by diminished mitochondrial energization and membrane barrier function in the late phase.

Animals↗
PubMed1996

Instability of Rts1 (drug-resistant factor) replicon: stabilization by DNA fragments derived from Rts1.

Rts1 is a large naturally occurring plasmid which has a kanamycin resistance gene and exhibits various temperature-sensitive phenotypes. A smaller derivative of plasmid, pOK, contains the Rts1 replicon and the kanamycin resistance gene of Rts1. This plasmid, pOK, is much more unstable than Rts1 at 42.5 degrees C. A DNA fragment, G3, 1590 nucleotides long from Rts1 DNA, stabilized pOK completely at 42.5 degrees C but only in the cis configuration. G3 did not change the copy number of pOK. The pOK derivative containing G3 was destabilized by the presence of a compatible plasmid containing G3. G3 has four inverted repeats, two 14-base direct repeats, and three ORFs. Smaller fragment of G3 also had a stabilization effect and these studies showed that the ORF does not play any role in stabilization.

Base Sequence↗
PubMed1996

Modification of the bi-directional sliding movement of actin filaments along native thick filaments isolated from a clam.

The properties of bi-directional sliding of F-actin prepared from rabbit skeletal muscle moving along clam thick filaments have been characterized in the presence of agents known to modify unloaded shortening velocity in muscle to determine if the sliding characteristics of actin are similar in the two directions of movement. Actin filaments moved at a fast velocity towards the central bare zone (11.1 +/- 0.2 microns s-1) and at a slower velocity away from the bare zone (3.9 +/- 0.3 microns s-1). Movement of filaments at the slow sliding velocity is thought to be sustained by a change in orientation of the myosin head. The Michaelis Menten constant (Km values) of approximately 0.3 mM in the presence of MgATP concentrations of 0.01-2.0 mM at an ionic strength of 43.5 mM were reduced to approximately 0.1 mM at low ionic strength (18.5 mM) although the Km values at the fast and slow sliding velocities at each ionic strength were similar. In the presence of constant concentrations of MgATP, increasing the MgADP concentrations from 0.5 to 2mM, decreased the bi-directional sliding velocity of actin. The data were well fitted with an equation described by Michaelis Menten kinetics yielding mean absolute Km and Ki values of 0.41 +/- 0.01 and 0.44 +/- 0.05 mM for the fast velocity and 0.29 +/- 0.07 and 0.45 +/- 0.02 mM for the slow velocity of sliding, respectively. The Km and Ki values were not significantly different from each other at either the fast or slow sliding velocities. The actin filament sliding velocity appeared to be controlled through the thick filament as actin was devoid of regulatory proteins and the presence of Ca2+ modified the MgATP dependent movement of actin. The pCa value for half maximal sliding velocity was 7.0 for both fast and slow velocities. The Km and Ki values and the Ca2+ sensitivity of the actin movement at the fast and slow sliding velocity are similar suggesting that no major biochemical changes have occurred in the myosin head as a result of a change in orientation.

Actins↗
PubMed1996

IL-1 is an important mediator for microcirculatory changes in endotoxin-induced intestinal mucosal damage.

Although small intestine is frequently injured in endotoxin shock, the exact pathological sequence has not been fully understood. The major objective of this study is to elucidate the role of interleukin (IL)-1 in endotoxin-induced microcirculatory disturbance of rat small intestine. Mucosal and submucosal microvessels of the rat ileum were observed by intravital microscope with a high speed video camera system and the attenuating effect of E5090, an inhibitor of IL-1 generation, on endotoxin-induced intestinal microcirculatory disturbances was investigated. Endotoxin infusion produced significant mucosal damage, but before these morphological changes became significant, microvascular stasis in villi, decreased red blood cell velocity, and increased leukocyte adherence to venular walls were observed in intestinal microcirculatory beds 30 min after endotoxin administration. Intestinal IL-1alpha levels were also significantly increased at that time. Endotoxin treatment enhanced chemiluminescence activity from neurophils and rapidly mobilized CD18 on leukocytes. E5090, which suppressed the IL-1 production in intestinal mucosa, attenuated the microcirculatory disturbances induced by endotoxin, and significantly reduced the subsequent mucosal damage. E5090 also attenuated the increased chemiluminescence activity and CD18 expression on leukocytes. In conclusion, the production of IL-1alpha is enhanced in the intestinal mucosa during endotoxin infusion. IL-1 may be an important mediator of microcirculatory changes, including decreased red blood cell velocity and increased leukocyte sticking and its activation, leading to the mucosal damage.

Acrylates↗