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H Matsuda

Publications and source records attributed to H Matsuda.

At least 595 records · Page 33Linked to original sources
PubMed1997

The evolution of cooperation in a lattice-structured population.

The evolution of cooperation among unrelated individuals is studied in a lattice-structured habitat, where individuals interact locally only with their neighbors. The initial population includes Tit-for-Tat (abbreviated as TFT, indicating a cooperative strategy) and All Defect (AD, a selfish strategy) distributed randomly over the lattice points. Each individual plays the iterated Prisoner's Dilemma game with its nearest neighbors, and its total pay-off determines its instantaneous mortality. After the death of an individual, the site is replaced immediately by a copy of a randomly chosen neighbor. Mathematical analyses based on mean-field approximation, pair approximation, and computer simulation are applied. Models on one and two-dimensional regular square lattices are examined and compared with the complete mixing model. Results are: (1) In the one-dimensional model, TFT players come to form tight clusters. As the probability of iteration w increases, TFTs become more likely to spread. The condition for TFT to increase is predicted accurately by pair approximation but not by mean-field approximation. (2) If w is sufficiently large, TFT can invade and spread in an AD population, which is impossible in the complete mixing model where AD is always ESS. This is also confirmed by the invasion probability analysis. (3) The two-dimensional lattice model behaves somewhat in between the one-dimensional model and the complete mixing model. (4) The spatial structure modifies the condition for the evolution of cooperation in two different ways: it facilitates the evolution of cooperation due to spontaneously formed positive correlation between neighbors, but it also inhibits cooperation because of the advantage of being spiteful by killing neighbors and then replacing them.

Animals↗
PubMed1997

Reduced resuscitation fluid volume for second-degree burns with delayed initiation of ascorbic acid therapy.

BACKGROUND: Oxygen radicals may play an important role in injury due to thermal burns. High-dose antioxidant ascorbic acid (vitamin C, Cenolete, Abbott Laboratory, Abbott Park, Ill) therapy reduces edema of burned and unburned tissue, lipid peroxidation, and subsequent resuscitation fluid volume requirement in experimental burn models. OBJECTIVE: To determine the hemodynamic effects of delayed initiation (2 hours after injury) of antioxidant therapy in patients with second-degree burns. DESIGN: Experimental study. MATERIALS AND INTERVENTION: Burns over 70% of body surface area were produced by subxiphoid immersion of 12 guinea pigs in 100 degrees C water for 3 seconds. The animals were resuscitated with Ringer's lactated solution according to the Parkland formula (4 mL/kg for 1% of burned body surface area during the first 24 hours) from 0.5 to 2 hours following injury, after which the resuscitation fluid volume was reduced to 25% of the Parkland formula. Animals received Ringer's lactated solution to which ascorbic acid (340 mg/kg during the first 24 hours) was added (vitamin C group [n = 6]) or Ringer's lactated solution only (control group [n = 6]). MEASUREMENTS: Heart rates, mean arterial blood pressure, cardiac output, hematocrit level, and water content in burned and unburned tissue were measured before injury and at intervals thereafter. RESULTS: There were no significant differences in heart rates (P = .29) and blood pressures (P = .53) between the 2 groups throughout the 24-hour study period. No animal died. The vitamin C group showed significantly lower hematocrit levels (P < .05) and significantly higher cardiac output values (P < .05) at 7 hours following burn injury and at intervals thereafter (P < .001). CONCLUSION: With delayed initiation of high-dose ascorbic acid therapy, the 24-hour fluid resuscitation volume was reduced to 32.5% of the Parkland formula, while maintaining adequate cardiac output values.

Animals↗
PubMed1997

Granulocyte colony-stimulating factor and interleukin-6-producing lung cancer cell line, LCAM.

BACKGROUND AND OBJECTIVES: We describe a case of granulocyte colony-stimulating factor (GCSF) and interleukin-6 (IL-6)-producing lung cancer. METHODS: A 53-year-old man underwent left upper lobectomy under diagnosis of lung cancer. The tumor obtained by a preoperative biopsy was analyzed. RESULTS: Preoperative data showed leukocytosis with left-shift of leukocytic morphology and thrombocytosis and an elevated serum GCSF level. Histological examination revealed poorly differentiated adenocarcinoma. A cell line, named LCAM, was established from the tumor and the cytokines in the culture medium were measured by enzyme immunoassay. GCSF and IL-6 were produced in large amounts by LCAM, but granulocyte-macrophage colony-stimulating factor (GMCSF) and interleukin-3 (IL-3) were not. A proportion of LCAM expressed GCSF receptor on the cell surface, but IL-6 receptor could not be detected. LCAM proliferation was inhibited in the culture with antihuman GCSF antibody in a dose-dependent manner. CONCLUSIONS: We suggest that LCAM proliferation is positively regulated by GCSF.

Granulocyte Colony-Stimulating Factor↗
PubMed1997

Failure to down-regulate Bcl-2 protein in thymic germinal center B cells in myasthenia gravis.

The most unusual characteristic of myasthenia gravis (MG) is that the thymus has germinal centers (GC). Cultured thymic lymphocytes from MG patients spontaneously produce anti-acetylcholine receptor antibodies, indicating that autoreactive B cells have escaped negative selection. To investigate the underlying mechanism, we examined the expression of the apoptosis-related protein Bcl-2 in GC B cells (defined as CD19+ CD38+ cells) in the thymus in 14 MG patients using three-color flow cytometry. GC in MG patients did not show the normal down-regulation of Bcl-2 (the frequency of Bcl-2+ GC B cells in the MG thymus and in control tonsils 54.3 +/- 16.2% versus 20.6 +/- 8.0%; mean +/- SD. p < 0.0001). In contrast, Bcl-2 in GC in the mediastinal lymph nodes from four patients was down-regulated to a relatively normal level. Using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) method to detect DNA fragmentation in situ, the frequency of TUNEL+ cells in GC in the MG thymus was lower than in control tonsils. These results suggest that autoreactive B cells which normally undergo apoptosis in GC may survive because of Bcl-2 up-regulation in this unusual location.

Adolescent↗
PubMed1997

Role of nitric oxide in oxygen transport in rat liver sinusoids during endotoxemia.

To evaluate the role of nitric oxide (NO) in hepatic microcirculation and liver injury during endotoxemia, we studied O2 transport in the hepatic microcirculation of endotoxin-infused rats. Rats were continuously infused with Escherichia coli lipopolysaccharide (LPS) (0.8 mg/kg/h) for 7 hours. LPS increased the plasma levels of NO2- + NO3- and aspartate transaminase (AST), and decreased the bile flow rate and hepatic adenosine triphosphate (ATP) level. Hepatic microcirculation was evaluated by two methods: reflectance spectrophotometry showed a decrease in the oxygenation of hemoglobin (Hb) in the liver, and dual-spot microspectroscopy indicated that LPS administration decreased blood velocity, the oxygenation of Hb, and O2 release from sinusoids to hepatocytes. The observed decreases in the O2 transport parameters were prominent in pericentral sinusoids. All of these phenomena were further aggravated by the administration of N(w)-nitro-L-arginine methyl ester (L-NAME) (5 mg/kg/h) plus LPS, and by aminoguanidine (AMG) (5 mg/kg/h) plus LPS, and these could be reversed by the concomitant administration of L-arginine (L-Arg) (100 mg/kg/h). These results suggest that deterioration of hepatic oxygen transport and liver function induced by endotoxin can be ameliorated by NO.

Adenosine Triphosphate↗
PubMed1997

Reduced resuscitation fluid volume for second-degree experimental burns with delayed initiation of vitamin C therapy (beginning 6 h after injury).

We studied the hemodynamic effects of delayed initiation (6 h postburn) of antioxidant therapy with high-dose vitamin C in second-degree thermal injuries. Seventy percent body surface area burns were produced by subxiphoid immersion of 12 guinea pigs into 100 degrees C water for 3 s. The animals were resuscitated with Ringer's lactate solution (R/L) according to the Parkland formula (4 ml/kg/% burn during the first 24 h) from 6 h postburn, after which the resuscitation fluid volume was reduced to 25% of the Parkland formula volume. Animals were divided into two groups. The vitamin C group (n = 6) received R/L to which vitamin C (340 mg/kg/24 h) was added after 6 h postburn. The control group (n = 6) received R/L only. Both groups received identical resuscitation volumes. Heart rates, mean arterial blood pressure, cardiac output, hematocrit level, and water content of burned and unburned tissue were measured before injury and at intervals thereafter. No animals died. There were no significant differences in heart rates or blood pressures between the two groups throughout the 24-h study period. The vitamin C group showed significantly (P < 0.05) lower hematocrits 8 and 24 h postburn, and higher cardiac outputs after 7 h postburn. At 24 h postburn, the burned skin in the vitamin C group had a significantly (P < 0.05) lower water content (73.1 +/- 1.1) than that of the control group (76.0 +/- 0.8). In conclusion, delayed initiation of high-dose vitamin C therapy beginning 6 h postburn with 25% of the Parkland formula volume significantly reduced edema formation in burned tissue, while maintaining stable hemodynamics.

Animals↗
PubMed1997

Discrepancy between blood flow and muscarinic receptor distribution in rat brain after middle cerebral artery occlusion.

To clarify whether muscarinic acetylcholine receptor (mAChR) binding can be a viable muscarinic neuronal marker which provides therapeutic information different from perfusional information in global brain, we evaluated the discrepancy between the distribution of cerebral blood flow (CBF), mAChR and its five subtypes of messenger ribonucleic acid (mRNA) in the acute (n=9) and chronic (n=8) phases of a middle cerebral artery (MCA) occlusion model and in sham-operated controls (n=6). In the acute phase, regional CBF was markedly reduced in the MCA territory, whereas mAChR was not reduced and the mRNA was reduced only slightly. In the chronic phase, mAChR was reduced markedly in the infarcted lesion and the mRNA was also reduced. The mAChR was slightly reduced in the ipsilateral substantia nigra and pontine nucleus because of remote effects; however, regional CBF in the substantia nigra was slightly increased and did not change in the pontine nucleus. The discrepancy between CBF and mAChR was clarified, and the tendency toward a reduction in mRNA in the acute ischaemic region without a reduction in mAChR suggested the presence of cholinergic neurons which were viable but hypometabolic. It is concluded that mAChR imaging may be of value for the assessment of the viable cholinergic neuron density in vivo.

Animals↗
PubMed1997

Characteristics of endogenous uveitis in Hokkaido, Japan.

BACKGROUND: Etiological characteristics of endogenous uveitis vary among areas and races around the world. There are few epidemiological reports on the etiology of uveitis from areas within Asia. We report statistical data on uveitis in Japan. METHODS: We reviewed all of the records of patients with endogenous uveitis who visited the Uveitis Survey Clinic of Hokkaido University Hospital in 1981 and 1994 and extended the survey to include new patients with uveitis seen over the 3-year period from 1992 to 1994. RESULTS: Bechcet's disease, sarcoidosis and Vogt-Koy-anagi-Harada disease were the three most frequently diagnosed diseases in both 1981 and 1994. The proportion of patients with unclassified uveitis decreased from 38% to 30% during the 13-year period from 1981 to 1994 as a result of the establishment of new disease categories during this time. Notable additions included human T-lymphotropic virus type 1-associated uveitis and tubuloinerstitial nephritis and uveitis syndrome. Sarcoidosis is now the most frequent endogenous uveitis in our clinic. CONCLUSION: Not only does the etiological basis of uveitis vary among ethnic groups but advances in clinical and basic research have changed the diagnostic approach to uveitis, altering the etiological profile over time.

Adolescent↗
PubMed1997

Attenuated inhibition of adrenergic contraction by nitric oxide in injured guinea pig femoral artery.

The present study aimed to examine the altered modulation of adrenergic contraction by nitric oxide and sensory neuropeptides in balloon-injured muscular artery. A guinea pig femoral artery (GPFA) was injured by a newly developed silastic microballoon catheter. The contralateral GPFA served as the control. The studied GPFAs consisted of six groups; control (C) and injured (I) GPFA, isolated at 0 days, and 2 and 8 weeks after injury (C0, I0, C2, I2, C8, and I8). Isometric tension was measured in the presence of indomethacin (10(-5) M), to exclude effects of cyclooxygenase-generated eicosanoids. Endothelial removal with the catheter was confirmed by histological examination. In each group, except for 10, NG-nitro-I-arginine methyl ester (L-NAME, 10(-6) M) induced significant augmentation of perivascular nerve stimulation (PNS)-evoked adrenergic contraction, which was blocked by L-arginine (3 x 10(-4) M). The degree of L-NAME augmentation in I8 was significantly smaller than that in C8 and I2. Capsaicin (10(-6) M) did not significantly affect PNS-contraction in any group, indicating that there was no sensory neuropeptide involvement in this contraction. In I8, acetylcholine (10(-6) M)-induced relaxation after noradrenaline (10(-5) M)-precontraction was significantly smaller than that seen in the other groups, except for I0, which was lacking in acetylcholine-induced relaxation. Histologically, injured GPFAs showed progressive intimal thickening. The present findings thus showed attenuated nitric oxide-mediated inhibition of adrenergic contraction, accompanying intimal thickening, in balloon-injured muscular artery, 8 weeks after injury.

Acetylcholine↗
PubMed1997

Histometric analysis of the distal pancreas in pancreatic head cancer.

To clarify the histological status of the pancreas tail after pancreatoduodenectomy (PD), fibrosis, islets of Langerhans, and A, B, and D cells were examined histometrically in surgical cases of pancreatic cancer. The same investigations were also performed during an autopsy examination of the pancreas tail of survivors of surgery who had received either PD or total pancreatectomy with segmental autotransplantation (SAT). In the surgical cases, fibrosis and the islet percentage compared with nonpancreatic cancer cases were significantly higher while the B cell ratio was significantly lower. In addition, in pancreatic cancer patients, the fibrosis and islet ratio in the group with a blocked pancreatic duct were higher while the B cell ratio was lower than in the group with an open pancreatic duct. A direct relationship between the islet ratio and the degree of fibrosis, and an inverse relationship between the B cell ratio and the degree of fibrosis, were thus found. From the autopsy cases, the fibrosis progressed and the islet ratio increased following PD, but after SAT only the islet ratio increased compared to the time of surgery. The progression of fibrosis after PD thus suggests the presence of some problems in both the surgical method and postoperative management.

Adult↗
PubMed1997

Myocardial histological changes in dilated cardiomyopathy during a long-term left ventricular assist device support.

As the myocardium in patients with dilated cardiomyopathy (DCM) is deteriorating progressively, resulting in a decrease in left ventricular function, patients with end-stage DCM may require implantation of a left ventricular assist device (LVAD) unless they undergo heart transplantation. Although LVAD has been reported to provide excellent hemodynamic support, no data are currently available about the effects of long-term LVAD support on the myocardium in patients with DCM. We describe two patients with end-stage DCM who underwent LVAD implantation and were supported with LVAD for 524 and 245 days, respectively. Serial myocardial biopsies showed increases in myocardial cell diameter and intercellular fibrosis, despite excellent hemodynamic support by LVAD. These data suggest that the myocardium in patients with end-stage DCM deteriorates progressively, even if the pre-load of the left ventricle is reduced by LVAD.

Adult↗
PubMed1997

Distribution of neuropeptide-containing nerve fibers in the human submandibular gland, with special reference to the difference between serous and mucous acini.

Distribution of neuropeptide Y (NPY)-, vasoactive intestinal polypeptide (VIP)-, galanin (GAL)-, substance P (SP)-, and calcitonin gene-related peptide (CGRP)-immunoreactive nerve fibers in the human submandibular gland was examined by the peroxidase-antiperoxidase method with attention to high-quality fixation and the condition of patients. NPY-, VIP-, and GAL-immunoreactive varicose fibers were densely distributed around the acini and ducts. Some of these fibers extended between acinar cells. The density of SP- and CGRP-immunoreactive fibers was relatively low. The number of NPY-, VIP-, and GAL-immunoreactive fibers around the mucous acini was significantly higher than around the serous acini. In the perivasculature, NPY-immunoreactive fibers were more numerous than other immunoreactive fibers. No somatostatin-, leucine-, or methionine-enkephalin-immunoreactive fibers were detected. Our findings suggest that a large number of periacinar VIP-, NPY-, and GAL-immunoreactive fibers may participate in regulating the synthesis of saliva and its secretion. Since the VIP-, NPY-, and GAL-immunoreactive fibers are more numerous around the mucous acini than around the serous ones, these fibers may take part more actively in regulating the secretory mechanisms in the mucous acini than in the serous ones. The relatively low number of CGRP- and SP-immunoreactive fibers suggests that they are less involved in the function of the human submandibular gland. Perivascular peptidergic fibers, especially NPY-immunoreactive fibers, may be involved in controlling local blood flow in this gland.

Aged↗
PubMed1997

Thoracoscopic enucleation of a large leiomyoma located on the left side of the esophageal wall.

Thoracoscopic enucleation through the right thorax was successfully performed for a large leiomyoma located on the left wall of the upper-middle esophagus. Using intraoperative esophagoscopy, the exact location of the tumor was identified by trans-illumination. Two sling tapes passed around teh esophagus made the procedure as easy as that for tumor located on the right wall of the esophagus. We considered that the thoracoscopic approach through the right thorax can be applied to various types of esophageal leiomyoma, even a large one located on the left side of the esophagus.

Adult↗
PubMed1997

Laparoscopic intragastric surgery for gastric leiomyoma.

Laparoscopic intragastric surgery (LIGS) was performed on a 63-year-old man with a gastric leiomyoma adjacent to the cardia. Because the tumor was about 5 cm in maximum diameter and showed ulceration, the possibility that the tumor was a leiomyosarcoma could not be ruled out preoperatively. Conventionally, major surgery has been performed on patients with a tumor located near the cardia, although it was not always malignant. Enucleation by LIGS enabled us to avoid excessive invasiveness and provided a favorable result. LIGS may be an appropriate new, minimally-invasive operation for gastric myogenic tumors and should be considered for such cases.

Humans↗
PubMed1997

Laparoscopic cholecystectomy and time-course changes in renal function. The effect of the retraction method on renal function.

BACKGROUND: Recently, the retraction method has been used to reduce intraabdominal pressure (IAP) during laparoscopic surgery. The purpose of this study was to determine the serial changes in renal function during laparoscopic cholecystectomy (LC) using the retraction method. METHODS: Urine output, effective renal plasma flow (ERPF), and glomerular filtration rate (GFR) were measured serially in seven patients who underwent LC with 12 mmHg pneumoperitoneum (High-IAP group) and five who underwent LC using the retraction method with 4 mmHg pneumoperitoneum (Low-IAP group). RESULTS: Urine output, ERPF, and GFR were decreased during pneumoperitoneum in the High-IAP group, whereas no significant changes in any of these parameters were observed in the Low-IAP group. CONCLUSIONS: Our findings demonstrate that reduction of IAP to 4 mmHg using the retraction method prevents the transient renal dysfunction caused by prolonged 12 mmHg pneumoperitoneum during LC, suggesting that the retraction method reduces the risk of perioperative renal dysfunction during laparoscopic surgery.

Adult↗
PubMed1997

Spool-like stent for the open sternum after cardiac operations.

Severe edematous heart after a cardiac operation is impossible to treat if there is compression of the heart due to the sternum. In these patients delayed sternal closure may be a useful procedure until the heart decreases in size. We devised a spool-like stent for the open sternum to maintain the optimal cardiac space for the severely edematous heart and to fix the chest wall to allow for management while the sternum is open.

Cardiac Surgical Procedures↗
PubMed1997

The contribution of Na+/H+ exchange to ischemia-reperfusion injury after hypothermic cardioplegic arrest.

BACKGROUND: Na+/H+ exchange has been reported to be one of the key mechanisms in myocardial ischemia-reperfusion injury. However, the effect of temperature on Na+/H+ exchange is not fully understood. METHODS: Sodium-propionate-induced cell swelling, an indicator of the function of the Na+/H+ exchanger, was measured in rat thymic lymphocytes. A Langendorff perfused rat heart model was also employed to investigate the effect of the pharmacologic inhibition of Na+/H+ exchange on the recovery of cardiac function after hypothermic ischemia. This was done using FR168888, an inhibitor of Na+/H+ exchange. RESULTS: In the in vitro study, rat lymphocytes were observed to swell at 17 degrees, 22 degrees, and 27 degrees C, indicating that the Na+/H+ exchanger remains functional even under hypothermic conditions. FR168888 was found to significantly inhibit Na+/H+ exchange-induced cell swelling, even at 17 degrees C. In the in vivo study, pretreatment with FR168888 was found to prevent the deterioration of ventricular function, even after 5 hours of hypothermic cardioplegic arrest. This was associated with a decrease in the reperfusion-induced elevation in resting tension. CONCLUSIONS: These results suggest that Na+/H+ exchange in the heart still occurs, even under hypothermic conditions, and contributes to reperfusion injury, even after hypothermic cardioplegic arrest.

Animals↗