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Biomedical subjects

T Ueno

Publications and source records attributed to T Ueno.

At least 343 records · Page 19Linked to original sources
PubMed1994

Effect of head up tilt on cerebral circulation.

This study was performed to study the effect of the head up tilt (HUT) on cerebral circulation across the time course (60 degrees HUT for 15 minutes) and across the different angles of HUT (15, 30, 45, 60 degrees HUT for 15 minutes). Cerebral circulation was continuously monitored during 15 minutes of HUT by the carotid Doppler flow meter, the transcranial Doppler flow meter, and the near infra-red spectrophotometer. The results show that the cerebral blood flow decreased during HUT and that the cerebral blood volume decreased initially and then gradually increased. And the magnitude of the effect may have the relationship with the angles of the HUT.

Blood Pressure↗
PubMed1994

Individual differences of cerebrovascular responses to gravitational stress--prediction of orthostatic intolerance.

This experiment was designed to investigate the individual differences in the cerebrovascular responses to orthostatic stress. Seven male volunteers were exposed to head-up tilt (HUT) at 60 degrees for 15 min and to lower body negative pressure (LBNP) at 30 mmHg for 25 min. We measured the flow velocity of the middle cerebral artery and the quantity of the oxygenated and deoxygenated hemoglobin (oxy-Hb and deoxy-Hb) in the brain. Based upon oxy-Hb change during exposure to HUT, we classified the subjects into two groups: 1) the "good responder" group in which the oxy-Hb gradually increased from the 5th to 10th minute of HUT; 2) the "bad responder" group in which the oxy-Hb stabilized at lower levels after the initial decrease. The oxy-Hb changes between the two groups were significantly different during exposure to LBNP. During exposure to HUT and LBNP, no significant difference was observed in blood pressure and heart rate between the two groups. Our results suggest that there might be an individual difference in the cerebrovascular responses to orthostatic stress.

Adult↗
PubMed1994

Free oxygen radicals contribute to platelet aggregation and cyclic flow variations in stenosed and endothelium-injured canine coronary arteries.

OBJECTIVES: The purpose of this study was to test the hypothesis that free oxygen radicals contribute to platelet aggregation and cyclic flow variations in stenosed and endothelium-injured coronary arteries. BACKGROUND: Although free oxygen radicals, such as superoxide anion and hydrogen peroxide, have been shown to alter platelet function in vitro, the potential role of free oxygen radicals has not been fully described in an in vivo model of coronary artery thrombosis. METHODS: Cyclic flow variations were produced in dogs by an external constrictor placed at the site of the left anterior descending coronary artery with injured endothelium. Blood flow in this artery was monitored by a pulsed Doppler flow probe. If cyclic flow variations were observed during postoperative days, dogs intravenously received superoxide dismutase plus catalase. In anesthetized dogs that did not develop an episode of cyclic flow variations, the effect of intracoronary infusion of xanthine plus xanthine oxidase or hydrogen peroxide on arterial blood flow velocity was studied. In platelet studies, the effect of free oxygen radicals and radical scavengers on platelet aggregation was examined. RESULTS: In conscious dogs with cyclic flow variations, superoxide dismutase plus catalase significantly reduced cyclic flow variations (n = 7), whereas saline infusion had no effect (n = 7). The infusion of xanthine plus xanthine oxidase or hydrogen peroxide significantly induced cyclic flow variations in four of six dogs or in five of seven dogs, respectively. In vitro platelet studies showed that xanthine plus xanthine oxidase or hydrogen peroxide significantly enhanced platelet aggregation, and superoxide dismutase or catalase significantly inhibited such aggregation. CONCLUSIONS: Reduction of free radical formation decreases platelet aggregation and may eliminate cyclic flow variations, whereas promotion of free radical generation enhances platelet aggregation and may induce cyclic flow variations. Thus, free oxygen radicals are an important mediator in this model.

Animals↗
PubMed1994

Smooth pursuit eye movements and express saccades in schizophrenic patients.

Abnormalities of saccades such as disinhibition have been hypothesized as one cause of smooth pursuit eye movement (SPEM) dysfunctions in schizophrenia. Thus, we studied saccadic eye movements in schizophrenics with SPEM dysfunction. Subjects were divided into three groups: 10 normal control subjects, 10 schizophrenic subjects without SPEM dysfunction and 10 schizophrenic subjects with SPEM dysfunction characterized by a cogwheel appearance. Visually guided saccades in gap and overlap paradigms (Saslow, 1967) were examined and saccadic reaction times (SRTs) were measured in all subjects. Only schizophrenics with SPEM dysfunctions tended to manifest excessive reflexive saccades, named express saccades (Fischer, 1987), in the gap paradigm. Moreover, most of them were also found to have express saccades in the overlap paradigm, whereas normal subjects and schizophrenic subjects without SPEM dysfunction did not show such phenomena under the same conditions. In particular, most express saccades in the overlap paradigm in schizophrenics with SPEM dysfunction, were found in movements to the right.

Adult↗
PubMed1994

Cultured rat hepatic sinusoidal endothelial cells express intercellular adhesion molecule-1 (ICAM-1) by tumor necrosis factor-alpha or interleukin-1 alpha stimulation.

This study investigated the expression of intercellular adhesion molecule-1, a leukocyte adhesion molecule, on cultured rat hepatic sinusoidal endothelial cells during stimulation with tumor necrosis factor-alpha or interleukin-1 alpha. Using immunoelectron microscopy and the immunogold technique against intercellular adhesion molecule-1, gold particles were shown to increase significantly on the surface of sinusoidal epithelial cells treated with tumor necrosis factor-alpha (100 U/ml) or interleukin-1 alpha (10 U/ml) for 8 h compared with unstimulated cells. In addition, semi-quantitative analysis of intercellular adhesion molecule-1 on the sinusoidal endothelial cells was performed by cytofluorometer. Even without stimulation, intercellular adhesion molecule-1 was weakly expressed. However, 8 h after tumor necrosis factor-alpha or interleukin-1 alpha treatment, the expression of intercellular adhesion molecule-1 on cells was increased in a dose-dependent manner. Kinetic analysis showed that the expression of intercellular adhesion molecule-1 on sinusoidal endothelial cells treated with these cytokines increased gradually from the beginning of stimulation to 24 h. These findings suggest that hepatic sinusoidal endothelial cells may mediate the direct interaction between leukocytes and sinusoidal endothelial cells by expressing leukocyte adhesion molecules such as intercellular adhesion molecule-1.

Animals↗
PubMed1994

The extracellular matrix in hepatocellular carcinoma shows different localization patterns depending on the differentiation and the histological pattern of tumors: immunohistochemical analysis.

This study investigated cells producing type I, III, and IV collagens, laminin, and fibronectin, the major components of the extracellular matrix, and compared their localization patterns in relation to the grade of tumor differentiation and the histological pattern of hepatocellular carcinoma. Type I, III, and IV collagens, laminin, and fibronectin were produced by tumor, endothelial, and Ito cells. Regarding their localization pattern in relation to the histological pattern of tumors, although the extracellular matrix was present in the subendothelial spaces of sinusoids in every histological pattern, the localization of these components in the intercellular spaces of tumor cells was most marked in hepatocellular carcinoma with a compact pattern. These results suggest that the extracellular matrix produced by tumor, endothelial, and Ito cells is deposited in appropriate positions in hepatocellular carcinoma to sustain the tissue structure showing different histological patterns. In relation to the grade of tumor differentiation, in most cases, Type I, III, and IV collagens and fibronectin were present in the subendothelial spaces of sinusoids and the intercellular spaces of some tumor cells, while little laminin was observed in well-differentiated small hepatocellular carcinoma (less than 10 mm diameter). In undifferentiated hepatocellular carcinoma, little extracellular matrix was observed, except around vessels. These results suggest that sinusoidal capillarization may not yet have occurred in the early stage of hepatocarcinogenesis, although it develops as the tumors increase in size and the tumor cells dedifferentiate. In undifferentiated hepatocellular carcinoma, tumor cells are too atypical to produce each extracellular matrix component.

Adult↗
PubMed1994

Fibrogenesis in acute liver injuries.

We describe changes in the hepatic extracellular matrix (ECM) and its producing cells in acute liver injuries, primarily referring to transforming growth factor-beta 1 (TGF-beta), which is the most important cytokine involved in fibrogenesis. In addition, we describe the relationship between vitronectin (VN) and plasminogen activator inhibitor 1(PAI-1) in the self regulating mechanism of TGF-beta action for fibrogenesis in acute viral hepatitis. In the very early stage of acute liver injury, following aggregation of platelets, immunolocalization of TGF-beta is observed in injured areas. And at the cell migration stage, the infiltration pattern of inflammatory cells was characterized by an ordered progression of inflammatory cells, beginning with platelets and followed by polymorphonuclear leukocytes and macrophages. Following recruitment of inflammatory cells to the necrotic area, it appears that TGF-beta could be produced and activated by these inflammatory cells, resulting in the intensification of active TGF-beta distributions in the injured area. At the fibrosis stage, TGF-beta could also be produced by Ito cells, endothelial cells and hepatocytes at the periphery of the necrotic area, and may play important roles in the promotion of production and accumulation of ECM components in injured regions. In addition, the consistent localization of PAI-1 with VN in ECM near the necroinflammatory areas suggests that PAI-1 and VN could be involved in the modulation of fibrogenesis in acute liver injuries. In many kinds of acute liver injuries, fibrogenesis is usually considered to be transient, and injured liver tissues able to nearly recover in order.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Protection against ischemic spinal cord injury: one-shot perfusion cooling and percutaneous topical cooling.

PURPOSE: We investigated the protective effect of two methods of hypothermia against ischemic spinal cord injury: one-shot perfusion cooling and percutaneous topical cooling. METHODS: Twenty-five rabbits were divided into five equal groups. The abdominal aorta was isolated proximally by a vascular clamp and distally by an inflated balloon catheter for 60 minutes. Group I served as control. In groups II (2.5 ml/min) and III (5.0 ml/min), hypothermic lactated Ringer's solution was infused for 3 minutes from the distal end of the catheter. Ice blocks were placed behind the backs of rabbits 30 minutes before ischemia in group IV. Group V underwent the procedures combined with those in groups II and IV (infusion of hypothermic solution plus placement of ice blocks). Another 15 rabbits underwent laminectomy at the L2 or L3 level. A temperature probe was inserted into the spinal cord to monitor cord temperature continuously during the procedures in all five groups (three rabbits per group). RESULTS: Neurologic status on the second postoperative day in groups IV and V was significantly superior to that in group I (p < 0.01), but the neurologic status of groups II and III did not differ significantly from the neurologic status of group I. The spinal cord temperature in groups II and III dropped rapidly with the infusion, but it rose again quickly. In contrast, the spinal cord was kept sufficiently hypothermic during ischemia in groups IV and V. CONCLUSIONS: We concluded that the percutaneous cooling method can keep the spinal cord sufficiently hypothermic during ischemia to lead to a significantly superior neurologic outcome.

Analysis of Variance↗
PubMed1994

Overproduction of Thermus aquaticus DNA polymerase and its structural analysis by ion-spray mass spectrometry.

We cloned the pol gene from the Thermus aquaticus YT-1 strain into a plasmid vector and constructed a high-level expression system of the gene in Escherichia coli. Six codons in the translational start region were changed to simple AT-type codons or codons which are most frequently used in E. coli by the genetic engineering techniques with retention of the amino acid sequence of the native enzyme. The modified pol genes were expressed under the lac promoter of pUC-type plasmid and 266,418 units of activity was obtained in a sonicated and heated crude extract from 2 g of E. coli cells bearing one of the recombinant plasmids, pTAQ9. Highly purified protein was subjected to structural analysis using a protein sequencer and an ion-spray mass spectrometer combined with reversed-phase HPLC (LC-MS). The primary structure of the DNA polymerase was identical with the amino acid sequence deduced from the nucleotide sequence of the pol gene as far as examined (about 95% of the sequence); though, several regions where small peptides of less than 5 residues were produced by lysyl endopeptidase digestion could not be sequenced.

Amino Acid Sequence↗
PubMed1994

Smooth pursuit eye movements and voluntary control of saccades in the antisaccade task in schizophrenic patients.

It has been hypothesized that a saccade control dysfunction is one cause of a smooth pursuit eye movement (SPEM) dysfunction in schizophrenia. We studied the voluntary control of saccades in schizophrenic patients with the SPEM dysfunction using an antisaccade task. The mean error rate in the antisaccade task was significantly higher in the two schizophrenic groups with and without a SPEM dysfunction than in the normal control group. Furthermore, the schizophrenic group with the SPEM dysfunction showed significantly more errors than the schizophrenic group without the SPEM dysfunction. These findings seem to suggest a close relationship between the SPEM dysfunction and the appearance of errors which indicates an inability to inhibit reflexive saccades voluntarily in the antisaccade task. However, 4 of 10 subjects with the SPEM dysfunction showed an error rate less than the mean error rate of the schizophrenic group without the SPEM dysfunction. So, a voluntary control disorder of saccades as the main cause of the SPEM dysfunction appeared to be unlikely. An interesting finding of this study was that many schizophrenic subjects with the SPEM dysfunction showed errors with the latencies similar to those in express saccades, particularly in the rightward direction. This finding may suggest a close relationship between the SPEM dysfunction in schizophrenic patients and some pathological conditions of express saccades such as disinhibition of express saccades.

Adult↗
PubMed1994

A patient with hepatic granuloma formation and angiotensin-converting enzyme production by granuloma cells during clinical relapse of hepatitis A.

Elevation of the serum angiotensin-converting enzyme (sACE) level and hepatic granulomas were found during a clinical relapse in a 22 year old patient with acute viral hepatitis type A (AVH-A). The serum transaminase level and sACE level remained high for more than 6 months. In the biopsied specimen of the liver, fibrous rings of granulomas composed of collagen types I, III, and V were observed. Furthermore, the localization of ACE was visible in the rough endoplasmic reticulum of epithelioid cells of granulomas in the liver under electron microscopy using the indirect immunoperoxidase method. These results suggest that granuloma cells in the liver caused by hepatitis A may be involved in ACE production. In addition, other diseases associated with the presence of granulomas in the liver, such as lymphoma, cytomegalovirus infection, visceral leishmaniasis, and lupoid hepatitis, were ruled out. However, the hepatic granulomas disappeared with the healing of AVH-A. In this regard, the present case is considered to be one of the very few cases of hepatic sarcoidosis.

Adult↗
PubMed1994

A case of pseudolymphoma of the liver.

A case of pseudolymphoma (reactive lymphoid hyperplasia) of the liver in a 66 year old female is presented. A tumor-like lesion was incidentally discovered in the liver during clinical follow up of diabetes mellitus. The hepatic lesion was resected because malignant lymphoma was suspected after a needle biopsy. Grossly, the lesion was well-defined and measured 1.0 x 1.5 x 1.0 cm. Microscopically, the lesion consisted of hyperplastic lymphoid follicles with distinctive germinal centers and interfollicular areas consisting of mature lymphocytes and plasma cells. An immunohistological study revealed that the lymphoid cells of the lesion were polyclonal in immunophenotypes. These histological and immunohistochemical findings strongly suggested a pseudolymphoma and not hepatic inflammatory pseudotumor. This case was diagnosed as pseudolymphoma of liver. Only a few cases of hepatic pseudolymphoma have so far been reported in the English literature.

Aged↗
PubMed1994

Overproduction of the bacterial flagellar switch proteins and their interactions with the MS ring complex in vitro.

The flagellar switch proteins (FliG, FliM, and FliN) of Salmonella typhimurium were overproduced in Escherichia coli and partially purified in soluble form. They were mixed with purified MS ring complexes (which consist of subunits of FliF protein) to examine their interactions in vitro. The degree of interaction was estimated by ultracentrifugation, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. From the band density on the gel, we estimated that FliG bound to the MS ring complex at an approximately 1:1 molar ratio (FliG:FliF), whereas FliM did so only at a 1:5 molar ratio (FliM:FliF). FliN did not bind to the MS ring complex by itself or in the presence of the other switch proteins. A possible configuration of the switch proteins is discussed.

Amino Acid Sequence↗
PubMed1994

Morphological observation on extrahepatic bile duct of golden hamsters fed a lithogenic diet: histochemical, ultrastructural and cell kinetic studies.

Cholelithiasis is often accompanied with disorders of the extrahepatic bile duct and pancreas. However, studies on changes of the extrahepatic bile duct in cholecystolithiasis have not shown this clearly. We therefore investigated sequential histologic changes, mucous secretion and DNA synthetic activity of the extrahepatic bile duct epithelium in cholecystolithiasis. Serial changes in the mucosal epithelial cells of the extrahepatic bile duct in golden hamsters treated with a lithogenic diet were examined by light and electron microscopy and an ultrastructural quantitative technique. In addition, epithelial cell kinetics were studied using bromodeoxyuridine (BrdU). After the 2nd week of diet, the extrahepatic bile duct showed an increase in goblet cells of the mucosal epithelium, a large number of secretory granules in the upper nuclear area of the epithelial cells and an increase in the BrdU-labeling index compared with the controls. These findings indicate that mucous secretion and cell turnover were enhanced in the mucosal epithelial cells of the extrahepatic bile duct in cholelithiasis, suggesting that the epithelial cells of the bile duct were protected and regenerating.

Animals↗
PubMed1994

A protease inhibitor, NCO-700, improves the contractile function in stunned canine myocardium.

To explore the role of calcium-dependent protease in the stunned myocardium, open-chest dogs underwent 15 min of left anterior descending coronary artery occlusion followed by 2 h of reperfusion. Dogs received a single bolus intravenous injection of either the protease inhibitor NCO-700 (n = 6) or saline (n = 6) 1 min before reperfusion followed by a 30-min infusion at the same dose. Regional myocardial function was assessed in terms of systolic wall thickening with an epicardial Doppler probe. The two groups exhibited comparable systolic thickening under baseline conditions and similar degrees of dyskinesis during occlusion. After reperfusion, recovery of contractile function, expressed as a percentage of the baseline value, was significantly greater in NCO-700-treated dogs as than in control dogs: -14.3 +/- 10.6 vs -48.9 +/- 7.2 (p < 0.05) at 15 min, 10.8 +/- 10.3 vs -31.1 +/- 9.0 (p < 0.05) at 30 min, 42.5 +/- 10.1 vs -16.4 +/- 9.1 (p < 0.005) at 1 h, and 47.5 +/- 8.3 vs -14.9 +/- 9.4 (p < 0.001) at 2 h. The data suggest that the protease inhibitor markedly improved contractile function in stunned myocardium by inhibiting intracellular protease activity.

Animals↗
PubMed1994

Structure-depolarizing activity relationship for achatin-I, a tetrapeptide with a D-Phe residue, and its derivatives toward the crayfish giant axon.

Achatin-I (Gly-D-Phe-Ala-Asp) is a tetrapeptide isolated from the ganglia of an African giant snail (Achatina fulica Férussac). The compound and its derivatives were synthesized, and their effects on the action potential of the crayfish giant axon elicited by electrical stimulation were examined by an intracellular recording method. The membrane potential after the action potential had fallen was elevated by some compounds at an acidic but not neutral pH level. An analysis of the structure-activity relationship for the activity to elevate the afterpotential at an acidic pH level, suggests that the factors favorable for activity were the beta-turn conformation, a beta- or gamma-carboxyl group in the C-terminal residue, appropriate hydrophobicity and/or bulkiness in the protecting groups for the alpha-amino group at the N-terminus, and the number of negative charges in the entire molecule.

Action Potentials↗