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M Suematsu

Publications and source records attributed to M Suematsu.

At least 73 records · Page 4Linked to original sources

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↗

Leukocyte-endothelium interaction in the rat mesenteric microcirculation during halothane or sevoflurane anesthesia .

BACKGROUND: The effects of inhalational anesthetics on the microcirculation, including leukocyte dynamics, remain to be clarified. The authors investigated halothane and sevoflurane anesthesia to determine if these agents evoked leukocyte adhesion through endothelial cell-dependent mechanisms involving such adhesion molecules. METHODS: Rats were anesthetized with halothane or sevoflurane in 100% oxygen and the lungs were mechanically ventilated. Leukocyte behavior in mesenteric venules was recorded through intravital video microscopy under monitoring microvascular hemodynamics. To examine the mechanisms for leukocyte rolling and adhesion, these studies were repeated after animals were pretreated with a monoclonal antibody against P-selectin (MAb PB1.3) or against intracellular adhesion molecule-1 (ICAM-1; MAb 1A29): P-selectin required for rolling of circulating leukocytes and ICAM-1 for firm adhesive interactions with leukocyte integrins. RESULTS: Under baseline anesthetic conditions (1 minimum alveolar concentration [MAC]), venular wall shear rates, an index of the disperse force on marginating leukocytes, in the sevoflurane-treated rats were about two times higher than those with halothane. At 2 MAC, halothane caused a marked arteriolar constriction and decreasing shear rates concurrent with an increasing density of venular leukocyte adhesion. Sevoflurane at 2 MAC induced leukocyte rolling and adhesion, which were attenuated by PB1.3 and 1A29, without alterations in the wall shear rates. Halothane-induced leukocyte adhesion was not prevented by PB1.3 but it was by 1A29. CONCLUSIONS: Halothane or sevoflurane anesthesia induces venular leukocyte rolling and adhesion: P-selectin upregulation plays a crucial role in leukocyte rolling and adhesion during sevoflurane anesthesia, whereas low-flow perfusion is likely to evoke ICAM-1-dependent leukocyte adhesion during halothane anesthesia.

Anesthetics, Inhalation↗

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↗

Electrophysiological characterization of cultured hepatic stellate cells in rats.

This study aimed to examine electrophysiological properties of cultured rat hepatic stellate cells (HSCs) using the whole cell configuration of patch-clamp technique. At least three different current components were identified. First, when the membrane was depolarized to voltages more positive than -40 mV, a transient outward K+ current was evoked. Second, membrane hyperpolarization below -60 mV evoked a sustained and inward-rectifying K+ current. The third component was a current flowing outward, which was activated when the cell was depolarized more positively than 0 mV. The channel for this current allowed Na+, K+, and Cl- to pass nonspecifically, suggesting the presence of hemi gap-junctional channel. Furthermore, a laser photobleaching technique revealed the presence of gap junctions between adjacent HSCs. A voltage-gated Ca2+ current, which is known to occur in smooth muscle cells, was searched for but was not detectable. These results suggest that membrane potential of HSCs is determined specifically by the two distinct K+ channels and by an intercellular mechanism involving gap-junctional communication.

Animals↗

Endogenous carbon monoxide suppression stimulates bile acid-dependent biliary transport in perfused rat liver.

This study aimed to investigate whether carbon monoxide (CO), a product of heme oxygenase that degrades protoheme IX, serves as an endogenous modulator for biliary transport. To that end, effects of zinc protoporphyrin IX (ZnPP), a heme oxygenase inhibitor, on the biliary transport were tested in perfused rat liver. Perfusion of 1 microM ZnPP abolished detectable levels of CO in the venous perfusate and increased bile acid-dependent bile output accompanying an increased secretion of bile salts. The ZnPP-induced choleresis coincided with a reduction of tissue guanosine 3',5'-cyclic monophosphate (cGMP) levels and a decrease in vascular conductance. On administration of 2.5 microM CO, ZnPP-elicited choleresis, decreases in vascular conductance, and cGMP levels were all attenuated. Treatment with 1 microM 8-bromoguanosine 3',5'-cyclic monophosphate (8-BrcGMP) partly attenuated the ZnPP-induced choleresis in concert with repression of vascular conductance. Furthermore, treatment of the liver with methylene blue, a guanylate cyclase inhibitor, evoked a choleresis similar to that induced by ZnPP. Thus endogenous CO suppression stimulates the biliary transport in part through a cGMP-dependent mechanism.

Animals↗

Chronic opiate-receptor inhibition in experimental congestive heart failure in dogs.

Acute administration of opiate-receptor antagonists has previously been shown to improve cardiac output aortic blood pressure, systolic ventricular performance, and the baroreflex function in conscious dogs with right-sided congestive heart failure (RHF). However, whether similar changes occur after chronic opiate-receptor inhibition in congestive heart failure is not known. To determine the chronic effects of opiate-receptor antagonism on RHF, we administered naltrexone (200 mg/day), a long-acting, orally active opiate-receptor blocking agent, to RHF and sham-operated animals for 6 wk. Naltrexone had no effects on resting heart rate, right atrial pressure, aortic pressure, or cardiac output in RHF dogs but increased the first derivative of right and left ventricular pressure with respect to time (dP/dt) at rest and improved the dP/dt response to isoproterenol. The inotropic responses to isoproterenol and forskolin in isolated right ventricular trabeculate muscle also were improved by chronic naltrexone in RHF. Myocardial beta-receptor density was reduced in the failing right ventricle compared with the control (58 +/- 3 vs. 108 +/- 6 fmol/mg protein, P < 0.01) but was unaffected by addition of naltrexone. Finally, naltrexone prevented the decline in baroreflex sensitivity that occurred in RHF (-0.2 +/- 0.5 vs. -6.0 +/- 0.5 ms/mmHg, P < 0.01). These effects of naltrexone did not occur in the shamoperated animals. Chronic opiate-receptor blockade with naltrexone attenuates the development of reduced adrenergic inotropic responsiveness and baroreflex subsensitivity that occur in RHF. Because there was a similar improvement in the forskolin response in the absence of significant alterations in myocardial beta-adrenoceptor density after naltrexone treatment, the improvement in adrenergically mediated inotropic effects probably is mediated via a postreceptor mechanism.

Animals↗

Constitutive expression of ICAM-1 in rat microvascular systems analyzed by laser confocal microscopy.

The present study aimed to demonstrate constitutive expression of the intercellular adhesion molecule (ICAM)-1 among arterioles, capillaries, and venules in the mesentery and liver and to examine the interaction between cultured endothelial cells and leukocytes in rats. ICAM-1 expression in the microvessels in vivo was visually demonstrated by laser confocal fluorescence microscopy. A monoclonal antibody against rat ICAM-1 (1A29) was labeled with fluorescein isothiocyanate, and the binding ratio between the fluorescence and immunoglobulin was determined for data calibration. Intravascularly administered fluorescein isothiocyanate-labeled 1A29 was distributed heterogeneously among the hierarchy of microvessels in the mesentery: postcapillary venules were the major portion expressing ICAM-1 constitutively, and the density of 1A29 bound to their endothelium was at least 10 times higher than that in true capillaries and arterioles in the same mesentery. On the other hand, the liver expressed ICAM-1 abundantly in sinusoids to the extent similar to that in central venules. These results suggest that postcapillary venules serve as an active gateway with the readiness to help adhere circulating leukocytes exposed to proinflammatory stimuli in acute inflammation.

Animals↗

Role of CD18-ICAM-1 in the entrapment of stimulated leukocytes in alveolar capillaries of perfused rat lungs.

This study aimed to examine the behavior of stimulated leukocytes in the pulmonary microcirculation. The leukocyte-endothelium interaction was visualized under physiological shear rates in perfused rat lungs using high-speed confocal laser video microscopy. Leukocytes labeled with carboxyfluorescein were stimulated with cytokine-induced neutrophil chemoattractant (CINC/gro), which caused L-selectin shedding and inverse upregulation of CD18. Neither unstimulated nor stimulated leukocytes exhibited rolling in either pulmonary arterioles or venules, whereas both were sequestered in capillaries. Approximately 50% of stimulated leukocytes showed a transient cessation of movement in pulmonary capillaries. The CINC/ gro stimulation, which inhibited leukocyte rolling and adhesion to mesenteric venules, reduced leukocyte velocity and increased leukocytes in pulmonary capillaries. Pretreatment with monoclonal antibodies against intercellular adhesion molecule-1 (ICAM-1) or CD18 attenuated these changes. Confocal microfluorography revealed constitutive expression of ICAM-1 not only in venules but also abundantly in capillary networks. These results suggest that selectin-independent, CD18-ICAM-1-dependent capillary sequestration is one of the major mechanisms by which activated leukocytes accumulate in the lungs.

Animals↗

[Effects of hyperoxia on the behavior of leukocytes in rat pulmonary microcirculation assessed by confocal laser scanning microscopy].

To study the dynamic interaction between blood cells and endothelial cells in the pulmonary microcirculation, we developed a method for observing leukocytes and erythrocytes in the microcirculation of perfused rat lungs by confocal laser scanning microscopy. We examined the behavior of leukocytes in the microcirculation of rat lungs exposed to hyperoxia, because oxygen toxicity is known to be associated with leukocyte infiltration and endothelial cell damage. Rats were divided into two groups: control (21% O2) and hyperoxia (90% O2 for 48 hours). Lungs were perfused with Krebs-Henseleit solution equilibrated with 21% O2 and 5% CO2 through an artificial lung. Leukocytes stained with carboxyfluorescein diacetate succinimidyl ester and erythrocytes stained with fluorescein isothiocyanate were added to the perfusate, and images of the cells were observed and recorded with a confocal laser scanning microscope and a high-speed video camera. The mean velocities of erythrocytes (Vr) in arterioles, capillaries, and venules of the control group were 1.52, 0.50 and 1.61 mm/sec, respectively. Also in the control group, the velocities of the leukocytes were divided by the mean velocities of the erythrocytes in the same arterioles, capillaries and venules (Vw/Vr) and the results were 0.96, 0.97, and 0.98, respectively. The Vw/Vr values for arterioles in the hyperoxia group were not significantly different from those in the control group, but the Vw/Vr values for capillaries and venules were 27% and 37% lower than their respective control values. Leukocyte sequestration was seen mainly in capillaries in the hyperoxic group. These results suggest that an increase in adhesion in capillaries and venules, such as that caused by adhesion molecules, might play a key role in the behavior of leukocytes in the pulmonary microcirculation during hyperoxia.

Animals↗

Differential changes of myocardial beta-adrenoceptor subtypes and G-proteins in dogs with right-sided congestive heart failure.

We have shown previously in dogs with right heart failure that the reduction of myocardial beta-adrenoceptor density occurs only in the failing right ventricle, while cardiac inotropic responses to beta-adrenergic stimulation are reduced in both the right and left ventricles. The purpose of the present study was to determine whether a post-receptor defect in the guanine nucleotide-binding regulatory proteins (G-proteins) existed which would explain, at least in part, the adrenergic subsensitivity in both ventricles of the heart failure dogs. Using both immunoblotting technique and the bacterial toxin-mediated ADP ribosylation assays, we found that the stimulatory G-protein (Gs) was reduced in both ventricles of the heart failure dogs. In contrast, there were no changes in the inhibitory G-protein (Gi). In addition, receptor subtype analysis showed that only beta(1)-adrenoceptors were reduced in the failing right ventricle of the heart failure animals. This study demonstrated that the reduction of beta-adrenoceptors in right heart failure was chamber-specific whereas the reduction of Gs was non-selective, occurring in both ventricles of right heart failure dogs. The findings further suggest that the reduction of Gs probably was caused by systemic neurohormonal activation, independent of local ventricular stress.

Adenosine Diphosphate↗

Subthreshold UV radiation-induced peroxide formation in cultured corneal epithelial cells: the protective effects of lactoferrin.

Acute exposure to suprathreshold ultraviolet B radiation (UV-B) is known to cause photokeratitis resulting from the necrosis and shedding of corneal epithelial cells. however, the corneal effects of low dose UV-B in the environmental range is less clear. In this study, subthreshold UV-B was demonstrated to cause non-necrotic peroxide formation in cultured corneal epithelial cells, which was attenuated by the major tear protein lactoferrin. Intracellular oxidative insults and cell viability of rabbit corneal epithelial cells (RCEC) were assessed by dual-color digital microfluorography using carboxydichlorofluorescin (CDCFH) diacetate bis (acetoxymethyl) ester, a hydroperoxide-sensitive fluoroprobe, and propidium iodide (PI), respectively. The magnitude of UV-induced oxidative insults was calibrated by concentrations of exogenously applied H2O2 which evoke compatible levels of CDCFH oxidation. Exposure of RCEC to low-dose UV-B (2.0 mJ cm-2 at 313 nm, 10.0 mJ cm-2 total UV-B) caused intracellular oxidative changes which were equivalent to those elicited by 240 microM hydrogen peroxide under the conditions of the study. The changes were dose dependent, non-necrotic, and were partially inhibited by lactoferrin (1 mg ml-1) but not by iron-saturated lactoferrin. Pretreatment with deferoxamine (2 mM) or catalase (100 U ml-1) also attenuated the UV-induced oxidative stress. The results indicate that UV-B comparable to solar irradiation levels causes significant intracellular peroxide formation in corneal epithelial cells, and that lactoferrin in tears may have a physiological role in protecting the corneal epithelium from solar UV irradiation.

Animals↗

Omeprazole attenuates oxygen-derived free radical production from human neutrophils.

Neutrophil-derived oxygen radicals have been implicated in the pathogenesis of gastrointestinal disorders such as acute gastric mucosal injury induced by ischemia-reperfusion or by nonsteroidal antiinflammatory drugs (NSAIDs). The objectives of the present in vitro and clinical study were to determine whether omeprazole inhibits the production of toxic oxidants from neutrophils and to evaluate whether this drug affects intralysosomal pH. The respiratory burst of human neutrophils were was measured by luminol-dependent chemiluminescence (ChL) assay. The lysosomal pH of neutrophil was assessed by the fluorescence intensity ratio of phagocytized FITC-dextran using a digital-fluorescence video microscope. In vitro studies revealed that omeprazole (1-100 microM) dose dependently inhibited the ChL value of purified neutrophils that were elicited by FMLP (f-methionyl-leucyl-phenylalanine) or opsonized zymosan. Lysosomal pH was also increased in a dose-dependent manner by pretreatment with omeprazole. Healthy volunteers administered omeprazole, 40 mg/d for 7 d, showed a significant reduction in ChL values in peripheral neutrophils. These results suggest that omeprazole can inhibit the production of toxic oxidants by activated neutrophils. The action of omeprazole may be associated with a malfunction of lysosomal oxidant-producing enzymes due to an elevated intralysosomal pH.

Adult↗

alpha 4 integrin plays a critical role in early stages of T lymphocyte migration in Peyer's patches of rats.

Lymphocyte recirculation through the blood flow circuit and lymphoid organs is important for the maintenance of immune defense, and is defined as lymphocyte homing. During the homing process, several adhesion molecules have been postulated to play an important role in lymphocyte recruitment from the vascular space. In the present study, we investigated the effect of a novel mAb against rat alpha 4 integrin (MR alpha 4-1) on the interaction of T lymphocytes with postcapillary venules (PCV) and their subsequent migration into the interstitium of Peyer's patches, using intravital video microscopy. T lymphocytes collected from intestinal lymph were labeled with a fluorochrome carboxyfluorescein diacetate succinimidyl ester and were than injected into the jugular vein of recipient rats. The microvasculature in the ileal Peyer's patches of recipient rats was observed sequentially by intravital fluorescence microscopy. In controls, lymphocytes exhibited rolling behavior which was followed by firm adhesion to the endothelium of PCV. The density of sticking lymphocytes gradually increased during the first 30 min. These initial interactions of lymphocytes with the PCV (rolling and adherence) were drastically inhibited by treatment with MR alpha 4-1, both when MR alpha 4-1 was preinfused into rats and when T cells were preincubated in vitro with MR alpha 4-1 before administration. MR alpha 4-1 also significantly inhibited the transendothelial migration of T lymphocytes, associated by the ratio of migration to adherence. However, once T lymphocytes migrated into the interstitium, treatment with MR alpha 4-1 did not affect the pattern of travel of these lymphocytes in the interstitium or their transport into the microlymphatics in the parafollicular area. Therefore, we conclude that alpha 4 integrins play a critical role in the rolling and sticking of T cells and their transendothelial migration in PCV of Peyer's patches.

Animals↗

Taurocholate induces directional excretion of bilirubin into bile in perfused rat liver.

The role of taurocholate, one of the major conjugated bile acids present in portal blood, in excretion of bilirubin from liver parenchyma to biliary and vascular compartments was studied in isolated perfused rat liver. Contents of bilirubin and carbon monoxide (CO) in the bile or venous effluents were determined by enzyme-linked immunosorbent microassay with the use of antibilirubin monoclonal antibody 24G7 and myoglobin-assisted spectrophotometry, respectively. In the presence of taurocholate, bilirubin excreted into the biliary compartment constituted greater than 90% of the total bilirubin excreted from the liver (0.26 nmol.min-1.g liver-1), corresponding to 60% of the outflow of CO into the venous effluents. In its absence, however, the total amount of bilirubin excreted into extrahepatic compartments was reduced to 27% of CO flux, and more than 90% of the excreted bilirubin was in the venous effluent. Thus a choleretic bile acid such as taurocholate is necessary for directional transport of bilirubin into bile in the perfused liver preparation.

Animals↗

Endotoxin stimulates lymphocyte-endothelial interactions in rat intestinal Peyer's patches and villus mucosa.

Although lymphocyte-endothelial cell interactions represent a key step in controlling the recruitment of lymphocytes into gut-associated tissues, its dynamic process in microvessels of lymphoid (Peyer's patches) and nonlymphoid (villus) regions of the small bowel remains poorly understood. We monitored the migration of fluorescence-labeled T lymphocytes into normal and lipopolysaccharide (LPS)-inflamed rat intestinal microvessels using intravital microscopy. In Peyer's patches, T lymphocytes selectively adhered to postcapillary venules, although such selectivity was not observed in submucosal venules of villi. T lymphocytes exhibited rolling behavior followed by firm adhesion in microvessels of both the Peyer's patches and the villi, with both types of adhesive interaction being mediated by alpha 4-integrins. The enhanced rolling and adherence of lymphocytes observed in Peyer's patches and submucosal venules of villi of LPS-treated rats were preceded by a reduction in shear rate and were mediated largely by alpha 4-integrins and partly by beta 2-integrins. In capillaries of intestinal mucosa, lymphocyte adherence occurred without rolling and was independent of alpha 4-integrins. LPS also significantly increased adherence of lymphocytes to villus capillaries, which was not mediated by either alpha 4- or beta 2-integrin. These observations demonstrate significant heterogeneity of lymphocyte-endothelial cell interactions within different regions of the intestinal mucosa.

Animals↗

Modulation of mitochondrion-mediated oxidative stress by nitric oxide in human placental trophoblastic cells.

Intracellular hydroperoxide generation in cultured human placental trophoblastic cells (HPTCs) was quantitatively monitored in the presence or absence of an NO synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME, 1 mM), by digital microfluorography with use of carboxydichlorofluorescein, a hydroperoxide-sensitive fluorogenic probe. In the absence of L-NAME, HPTCs displayed a time-dependent gradual elevation of the fluorescence, suggesting the ability to produce oxidants spontaneously. In the presence of L-NAME, however, the fluorescent response in these cells increased further; the oxidative impact elicited by L-NAME treatment for 30 min was equivalent to that induced by application of 230 microM tert-butyl hydroperoxide for 5 min. This oxidative process was completely blocked by rotenone, a reagent that interferes with electron entry into complex I of the mitochondrial respiratory chain. On the other hand, antimycin A, which blocks mitochondria at the distal site of the ubiquinone pool, potentiated the L-NAME-induced oxidative change. These findings suggest that constitutive levels of nitric oxide production contribute to regulation of mitochondrion-derived intracellular oxidant generation in HPTCs.

Cell Separation↗

Mitochondrial aldehyde dehydrogenase in diabetes associated with mitochondrial tRNA(Leu(UUR)) mutation at position 3243.

OBJECTIVE: To ascertain why alcohol is prone to manifest unpleasant effects in diabetes associated with mitochondrial tRNA(Leu(UUR) mutation at position 3243 (DM-Mt3243), we investigated the genotype of aldehyde dehydrogenase (ALDH) 2 and alcohol dehydrogenase 2 (ADH2) in DM-Mt3243. RESEARCH DESIGN AND METHODS: Nineteen unrelated patients with DM-Mt3243 were included in the study (12 men and 7 women). They were recruited from approximately 700 diabetic patients at three different institutes, without prior information of alcohol habit. ALDH2, ADH2, and 3243 mutation were genotyped by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) methods. There were 461 unrelated Japanese individuals and 170 non-3243 mutant NIDDM patients enrolled as control subjects. RESULTS: In the DM-Mt3243 group, 15 (79%) patients had inactive ALDH2 and 18 (95%) had atypical ADH2. The frequency of the inactive ALDH2 genotype was higher than that in the normal control subjects (P < 0.002) and that in the NIDDM control subjects (P < 0.003). However, the frequencies of ADH2 genotype in the DM-Mt3243 group, the normal control subjects, and the NIDDM control subjects were not different. CONCLUSIONS: Inactive ALDH2 genotype was frequently observed in DM-Mt3243. It suggests that DM-Mt3243 is associated with ALDH2 inactivity. We speculate the trait of acetaldehyde accumulation on ALDH2 inactivity may favor mitochondrial DNA abnormalities, thereby worsening ATP production and impairing insulin secretion. In addition, the interaction of ALDH1 and ALDH2 may alter the retinoid metabolism in the pancreas, thereby influencing insulin secretion and precipitating diabetes. Thus, this association of ALDH2 genotype with DM-Mt3243 provides insight into the etiology of diabetes in the mitochondrial diseases.

Adult↗