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Biomedical subjects

Y Tsukamoto

Publications and source records attributed to Y Tsukamoto.

At least 163 records · Page 9Linked to original sources
PubMed1994

M and L cones in macaque fovea connect to midget ganglion cells by different numbers of excitatory synapses.

Visual acuity depends on the fine-grained neural image set by the foveal cone mosaic. To preserve this spatial detail, cones transmit through non-divergent pathways: cone-->midget bipolar cell-->midget ganglion cell. Adequate gain must be established along each pathway; crosstalk and sources of variation between pathways must be minimized. These requirements raise fundamental questions regarding the synaptic connections: (1) how many synapses from bipolar to ganglion cell transmit a cone signal and with what degree of crosstalk between adjacent pathways; (2) how accurately these connections are reproduced across the mosaic; and (3) whether the midget circuits for middle (M) and long (L) wavelength sensitive cones are the same. We report here that the midget ganglion cell collects without crosstalk either 28 +/- 4 or 47 +/- 3 midget bipolar synapses. Two cone types are defined by this difference; being about equal in number and distributing randomly in small clusters of like type, they are probably M and L.

Animals↗
PubMed1994

A proposed staging system for primary gastric lymphoma.

BACKGROUND: Although primary gastric lymphoma is the most common extranodal lymphoma, no specific staging system exists. METHODS: The authors reviewed 98 cases histologically classified according to the Working Formulation, including low grade B-cell lymphoma of mucosa-associated lymphoid tissue type. Survival rates were calculated by the Kaplan-Meier method according to T, N, and M of the general rules of the International Union Against Cancer TNM system. The definitions of these categories are as follows: T1, tumor invades the lamina propria or submucosa; T2, the muscularis propria; T3, the subserosa; T4, the serosa without invasion of adjacent structures; T5, adjacent structures; N0, no regional lymph node metastasis; N1, perigastric lymph nodes within 3 cm of the edge of the primary tumor; N2, perigastric lymph nodes more than 3 cm from the edge of the primary tumor or in lymph nodes along the left gastric, common hepatic, splenic, or celiac arteries; N3, paraaortic and hepatoduodenal lymph nodes and/or other intraabdominal lymph nodes; N4, beyond N3; M0, no distant metastasis; and M1, positive. RESULTS: The overall 5-year survival rate was 83.5%; it was 100% in T1, 82.4% in T2, 84.2% in T3, 52.9% in T4, and 33.3% in T5; 93.9% in N0, 90.5% in N1, 66.2% in N2, and 44.4% in N3/N4; and 86.0% in M0 and 25.0% in M1. Based on these results, the authors proposed a new staging system as follows: Stage I, T1/N0, N1/M0; Stage II, T1/N2/M0, T2,T3/N0,N1,N2/M0; Stage III, T4,T5/any N/M0, any T/N3, N4/M0; and Stage IV, any T/any N/M1. According to this system, the 5-year survival rate significantly decreased as the stage progressed: 100% in Stage I, 88.9% in Stage II, 52.1% in Stage III, and 25.0% in Stage IV. In Stages I and II, survival rates were not significantly different whether chemotherapy was done or not, whereas in Stage III all patients treated with surgery alone died. CONCLUSIONS: This staging system is useful for assessing prognosis of and deciding a therapeutic plan for primary gastric lymphoma.

Adult↗
PubMed1994

Characterization of a Rana catesbeiana lectin-resistant mutant of leukemia P388 cells.

Sialic acid-binding lectin (SBL-C) from Rana catesbeiana eggs inhibits the growth of tumor cells such as P388 and L1210 leukemia cells (K. Nitta et al., Cancer Res., 54: 920-927, 1994). Here we report the establishment of an SBL-resistant P388 variant cell line, RC-150. Both P388 and RC-150 cells were agglutinated by SBL-C; however, growth of RC-150 cells was unaffected by SBL-C. Cytoplasmic free Ca2+ concentration and transglutaminase activity of RC-150 cells were 0.5 (110 nM) and 3 times (0.62 nmol/mg/min) as high as those of P388 cells, respectively. Microvilli and microplicae were observed on the surface of P388 cells by scanning electron microscopy but were rarely seen on RC-150 cells. Dansylcadaverine-labeled SBL-C bound to both P388 and RC-150 cells. Binding of SBL-C to these tumor cells appears to be mediated by two species of wheat germ agglutinin-stained cell membrane sialoglycoproteins. Labeled SBL-C entered P388 but not RC-150 cells, suggesting that internalized SBL-C acts as an inhibitor of cell proliferation.

Agglutination↗
PubMed1994

The effect of additive hyaluronic acid on animal joints with experimentally reduced lubricating ability.

A series of in vitro experiments demonstrated a clear effect of additive hyaluronic acid (HA) on animal joints with experimentally reduced lubricating ability. Eleven canine hip joints were utilized and the experimental conditions tested were: i) intact joints, ii) after washing the joint surfaces, and iii) after adding 1% HA to them. The frictional coefficient of every joint increased after washing and subsequently decreased after adding HA. The mean values were 0.007 (SD 0.004) on the intact joints, 0.020 (SD 0.009) after washing, and 0.013 (SD 0.005) after the addition of HA. The differences between the three values of frictional coefficients were shown to be statistically significant (p < 0.01).

Animals↗
PubMed1994

Effects of FK506, an immunosuppressive agent, on genesis of water-immersion stress-induced gastric lesions in rats.

We examined the effects of FK506, an immunosuppressive agent, on the genesis of water immersion stress-induced gastric lesions in rats. Using high-performance liquid chromatography, four kinds of prostaglandins, ie, 6-keto-prostaglandin F1 alpha, prostaglandin F2 alpha, prostaglandin E2, and prostaglandin D2, were detected, and no leukotrienes were detected in gastric mucosa in rats without stress. After 6 hr of stress, gastric lesions developed with decreases in all prostaglandin contents, and the emergence of peptide leukotrienes was observed. Intramuscular administration of FK506 (0.1, 0.25, 0.5, 1.0, and 2.0 mg/kg) reduced lesion index dose-dependently. Administration of FK506 at doses over 0.25 mg/kg decreased all prostaglandin contents, but did not affect the increase in leukotriene contents. Pretreatment with famotidine or omeprazole reduced lesion index, and the protective effects were equivalent to those of 1.0 mg/kg of FK506, although FK506 did not affect gastric secretion during water-immersion stress. Water-immersion stress did not change the activities of xanthine oxidase in either stomach or serum. Polyoxyethylene-modified superoxide dismutase did not prevent gastric lesions. Water-immersion stress significantly increased myeloperoxidase activity in gastric mucosa, and FK506 reduced the increase in myeloperoxidase activity induced by stress. From our results, other factors besides gastric acid secretion and tissue eicosanoid contents, such as chemoattractant factor, might also be involved in the genesis of water-immersion stress-induced gastric lesions in rats.

Animals↗
PubMed1994

The disposition of the tolcapone 3-O-methylated metabolite is affected by the route of administration in rats.

Catechol-O-methyltransferase (COMT) catalyses the transfer of the methyl group from S-adenyl-L-methionine (SAM) to one of the hydroxy groups of a catechol, usually the hydroxy group in position 3. COMT is present mainly in a soluble form (S-COMT) in the cytosol, but a small fraction is bound to cell membranes (MB-COMT). MB-COMT has higher affinity for the catechol substrate than does S-COMT by a factor of > 10, and high MB-COMT activity is observed in the intestinal muscle layer. The present study investigates the effect of the administration route on the disposition of the tolcapone 3-O-methylated metabolite following intravenous and oral tolcapone administration in rats. Tolcapone is a substrate for COMT although the 3-O-methylated metabolite produced has no pharmacological actions. The 3-O-methylated metabolite was eliminated very slowly following oral administration of tolcapone, and its concentration approached a plateau level, which was in contrast to the situation following intravenous administration of tolcapone. It is thought that the oral dose of tolcapone receives a high exposure to MB-COMT in the intestinal muscle layer during its absorption, and tolcapone seems to form a complex with MB-COMT having a high affinity constant (i.e. a very low Ki). The fraction of the intravenous dose of tolcapone metabolized to the 3-O-methylated metabolite at 10 mg kg-1 was 2.6%, whereas those of the oral doses, which were corrected by the bioavailability, were 5.4% for 20 mg kg-1 and 2.7% for 40 mg kg-1.

Administration, Oral↗
PubMed1994

Asymptomatic carotid lesions and silent cerebral infarction.

BACKGROUND AND PURPOSE: Few studies have investigated the relationships between asymptomatic carotid lesions and silent infarcts confirmed on magnetic resonance imaging. METHODS: A consecutive series of 117 subjects (average age, 62 +/- 9.4 years) who were free from neurological deficit but had at least one established risk factor for stroke were investigated by B-mode carotid ultrasonography and magnetic resonance imaging of the brain. Carotid lesions were evaluated by plaque score, maximum percent stenosis, and the existence of ulcerated lesions. The relations between the carotid lesions and the incidence, size, or localization of the brain lesions were investigated. RESULTS: The incidence of silent infarcts was 42% in all subjects and significantly increased with advancing age (P < .05). Most lesions were smaller than 1 cm in diameter and were usually localized in the subcortical white matter or the basal ganglia. The percentage of subjects with infarcts increased significantly as the plaque score increased (P < .05) or when subjects had high-grade stenosis (P < .05) or ulcerated lesions (P < .01). These relationships were also noted in each decade of age. A higher incidence of larger lesions (> 1 cm) was found in the brain hemisphere ipsilateral to the carotid lesion, particularly in subjects with high-grade stenosis or ulcerated lesions (P < .01). Multivariate analysis indicated significant correlations with silent infarcts for age, hypertension, and plaque score. CONCLUSIONS: Both the severity and characteristics of asymptomatic carotid lesions estimated by B-mode ultrasonography were closely related to the appearance of silent infarcts. These results demonstrate that noninvasive assessment of carotid lesions can be useful in predicting the existence of silent cerebral infarction even in patients free from neurological deficits.

Adult↗
PubMed1994

Paradoxical embolism as a cause of ischemic stroke of uncertain etiology. A transcranial Doppler sonographic study.

BACKGROUND AND PURPOSE: This study was designed to test the hypothesis that paradoxical embolization would be a cause of embolic strokes and transient ischemic attacks in patients with stroke of uncertain etiology in all age groups. METHODS: Thirty patients who had stroke of uncertain etiology were studied. They were divided into the following three groups: 13 patients with sudden onset (group A), 11 patients with subacute onset (group B), and 6 asymptomatic stroke patients (group C). Eleven patients with stroke of obvious etiology (group D) and 11 normal healthy volunteers (group E) were also studied as controls. In all patients transcranial Doppler sonography and contrast echocardiography were recorded simultaneously after intravenous injection of the contrast medium. Findings of positive patient foramen ovale in contrast echocardiography or "chirp" sounds in transcranial Doppler sonography were defined as positive for paradoxical contrast embolization. Radioisotope phlebography of the lower extremities and pulmonary scintigraphy, using technetium-99 macroaggregated albumin, were performed in all 17 patients who had positive findings of paradoxical contrast embolization and in 12 patients whose findings were negative. RESULTS: Positive findings of paradoxical contrast embolization were found in 17 subjects by transcranial Doppler sonography but in only 8 on contrast echocardiography. These positive findings were detected more frequently in group A (77%) than in groups B, D, and E (9%, 18%, and 9%, respectively) (P < .05). In group C, 4 of 6 patients (67%) had positive findings. There were positive findings on both phlebography and pulmonary scintigraphy only in 6 group A patients, with positive findings of paradoxical contrast embolization. CONCLUSIONS: Transcranial Doppler sonography is a sensitive detector of right-to-left shunts. Paradoxical cerebral embolization might be frequent in patients with stroke of unknown etiology, especially when the stroke is of sudden onset.

Adult↗
PubMed1994

[Partial purification and properties of deoxyribonucleases from eggs and liver of Xenopus laevis. Comparison with deoxyribonuclease II from bovine spleen].

Deoxyribonucleases from eggs and the liver of Xenopus laevis were partially purified by DEAE-cellulose and heparin-Sepharose affinity column chromatographies. The fractions having egg and liver DNase activities were eluted on high performance liquid chromatography through TSK gel G3000SW at the molecular weights of 41.5 and 45 kDa, respectively. The frog DNases hydrolyzed a native DNA over a heat-denatured DNA, and also formed double-strand cuts not only in linear lambda-DNA but also in closed circular pBR322DNA. The pH optimum of the DNases was 4.5-5.0 in 50 mM acetate buffer. These enzyme activities were abolished by treatment at 80 degrees C for 5 min and pH 2, 3 or 12 for 1 h. The enzymes act in such a manner as deoxyribonuclease II (from bovine spleen)-type nuclease with respect to substrate specificity, optimum pH and cation dependence.

Animals↗
PubMed1994

[Adaptation and effects of ileal reservoir on ileo-proctostomy following total colectomy in dogs].

We examined postoperative adaptation and effects of J-pouch reservoir on ileo-proctostomy following total colectomy in dogs. End to end (E-E; n = 5) or J-pouch (J-P; n = 5) anastomosis was performed after resection of total colon and the rectum 3 cm above the peritoneal reflexion. Gastrointestinal motility with strain gauge force transducers (SG) and transit time with barium meal under the fluoroscopy were recorded 6 months after total colectomy. Then, histological changes of seven specimens from totally resected ileum in J-P and E-E vs control (normal ileum; n = 5) were measured with hematoxylin-eosin and PYY immunohistochemical stains. Propagation rate of interdigestive migrating complex (IMC) from jejunum to ileum was significantly lower in J-P (64.8 +/- 13.2%) than in E-E (98.6 +/- 1.2%) (p < 0.001). Oro-neorectal transit time (ONTT) in E-E (138 +/- 10 min) was shorter (p < 0.05), but ONTT in J-P (189 +/- 26 min) was significantly longer (p < 0.01) than oro-caecal transit time (OCTT) in preoperative control (165 +/- 19 min; n = 10). There was no difference about length of villi among control, E-E and J-P, but length of crypts in J-P (0.59 +/- 0.08 mm) was longer than that in E-E (0.27 +/- 0.02 mm) and normal ileum (0.34 +/- 0.07 mm) (p < 0.01). PYY positive cells in J-P were more than in E-E and control at any site of ileum and total number of PYY positive cells in J-P (168 +/- 18) significantly increased than that in E-E (111 +/- 16) and control (103 +/- 14) (p < 0.05). Thus, increase of PYY positive cells in J-P inhibits gastrointestinal motility and transit. Delayed transit time and crypts elongation were intestinal adaptation that assists the absorption of luminal contents. Therefore, it suggested that J-pouch reservoir had advantage to ileo-proctostomy following total colectomy in dogs.

Adaptation, Physiological↗
PubMed1994

Sequential observation of gastric ulcer healing by endoscopic ultrasonography.

BACKGROUND: The relationship between superficial findings and the inner structure of gastric ulcers is unclear. The present study was undertaken to clarify the relationship between them. METHODS: In the first study, 43 patients with active gastric ulcers were examined by endoscopic ultrasonography (EUS) in each stage of Sakita's endoscopic classification. In the second study, 16 patients with gastric ulcer scars were examined by EUS in both S1 stage and S2 stage. RESULTS: Ulcer area, ulcer length, thickness of the ulcer base, and diameter of the crater differed significantly in each endoscopic stage. Ulcer area, ulcer length, and thickness of the ulcer base differed significantly even between S1 stage and S2 stage. Mean ulcer area in S1 stage was 96.9 mm2; this shows that the ulcer scar in S1 stage is incomplete with regard to tissue contraction. Although ulcer area in S2 stage had shrunk significantly compared with that in S1 stage, it still remained 53.3 mm2. This implies that the risk of local recurrence remains even in S2 stage. CONCLUSIONS: Sequential observation by EUS showed that the healing of the ulcer surface strongly reflected the healing within the ulcers.

Adult↗
PubMed1994

New technique using intraductal ultrasonography for the diagnosis of bile duct cancer.

We investigated the extent to which BDca can be visualized and diagnosed via a percutaneous fistula using IDUS. IDUS was performed in 42 cases, including 15 of normal bile ducts; 12 of choledocholithiasis, and 15 of BDca. The depth of invasion of the BDca was diagnosed with a 93% accuracy rate by visualizing the EP or MA or both. The infiltration of BDca into the surrounding organs was clearly visualized and diagnosed with an accuracy of 100% in the RHA, 93% in the PV, and 93% in the pancreas. These accuracy rates were higher than those obtained by computed tomography or angiography. We believe, therefore, that IDUS should be further studied as a diagnostic modality for staging malignancy in the biliary field.

Bile Duct Neoplasms↗
PubMed1994

Intraductal ultrasonography for the examination of duodenal papillary region.

The purpose of this study was to provide basic criteria for interpreting images of the normal duodenal papillary region obtained by intraductal ultrasonography at the frequency of 20 MHz. Our in vitro examination of autopsy specimens from 15 patients revealed that the images could be classified into three patterns according to the spatial relationships between the duodenal muscularis propria and the bile duct, or the common duct. Oddi's muscle was clearly demonstrated surrounding the mucosa of the bile duct or the common duct, which was visualized as a hypoechoic layer. The images obtained using in vivo examination of 60 patients with pancreato-biliary disease via either the percutaneous or the peroral approach were similar to the images obtained in vitro. In eight patients with cancer of the papilla of Vater, the tumor was demonstrated clearly on intraductal sonograms. The intraductal imaging features of the normal papillary region were clarified, and the clinical usefulness of this technique in the evaluation of the tumor extent in patients with cancer of the papilla of Vater is suggested.

Ampulla of Vater↗
PubMed1994

Reactivity of cerebral blood flow to carbon dioxide in hypertensive patients: evaluation by the transcranial Doppler method.

OBJECTIVE: To evaluate hypertensive cerebral involvement before cerebrovascular accidents. DESIGN: Cerebral microvascular responses to changes in the arterial partial pressure of CO2 (pCO2; the CO2 reactivity) were compared among patients with different stages and severity of hypertensive disease. PATIENTS: Fifty-eight patients with hypertension, 11 with borderline hypertension, 15 hypertensives with cerebral infarction and 58 normotensive controls were studied. METHODS: The cerebrovascular CO2 reactivity was determined by measuring simultaneously the end-tidal pCO2 and the blood flow velocity in the middle cerebral artery using transcranial Doppler sonography under hypocapnic, normocapnic and hypercapnic conditions. RESULTS: CO2 reactivity was impaired in the hypertensive patients compared with in the normotensive controls, but less so than in the symptomatic hemisphere of the hypertensive patients with cerebral infarction. The CO2 reactivity in the borderline hypertensive patients was greater than that in both the symptomatic and asymptomatic hemispheres of the hypertensive patients with cerebral infarction. In the subjects without cerebral infarction, two risk factors for cerebral atherosclerosis (age and hypertension) were negatively correlated with cerebrovascular CO2 reactivity. In the hypertensive patients age and the estimated duration of hypertension were negatively correlated with cerebrovascular CO2 reactivity. CO2 reactivity in the patients with hypertensive or arteriosclerotic retinopathy or ST-T changes on their electrocardiogram was impaired compared with that in the patients without such changes. CONCLUSIONS: Hypertension affected the microvascular reactivity of the brain before the development of cerebrovascular accidents, and its effect varied dependently on the extent of involvement of other target organs.

Adult↗
PubMed1994

Differential diagnosis between benign and malignant localized stenosis of the main pancreatic duct by intraductal ultrasound of the pancreas.

OBJECTIVES: Our objectives in this study were to differentiate between pancreatic cancer (PC) and chronic pancreatitis (CP) in cases with localized stenosis of the main pancreatic duct (MPD) by an intraductal ultrasound (IDUS) probe which were detected on pancreatogram. METHODS: We inserted the IDUS probe (30 MHz) into the MPD in all cases and scanned the stenotic site in 23 of 26 cases (88.5%) in vivo. In all 26 patients, the stenotic site was surgically resected, and IDUS scanning was also performed on the resected specimens. Findings from IDUS were compared with those from histology. The diagnostic ability of IDUS was compared with that of endoscopic ultrasonography (EUS), computed tomography (CT), and endoscopic retrograde pancreatography (ERP). RESULTS: The IDUS images of localized stenosis were classified into two types: type I showed an echorich area surrounded by an echo-poor margin and was found in 14 PC patients and one CP patient; type II showed a ring-like echolucent band surrounded by a fine reticular pattern and was found in 11 CP. Therefore, we considered that type I tended to be characteristic of PC, whereas type II tended to be characteristic of CP. Sensitivities of EUS, CT, ERP, and IDUS in diagnosing PC were 92.9% (13/14), 64.3% (9/14), 85.7% (12/14), and 100% (14/14), respectively. Specificities of EUS, CT, ERP, and IDUS were 58.3% (7/12), 66.7% (8/12), 66.7% (8/12), and 91.7% (11/12), respectively. CONCLUSIONS: IDUS examination might be useful in the diagnosis of patients with localized stenosis of the MPD, but its precise role in the diagnostic work-up of patients with pancreatic diseases remains to be determined by further studies.

Chronic Disease↗
PubMed1994

Ultrasonographic angiography in gallbladder diseases.

Ultrasonographic (US) angiography was performed by sonographic examination with injection of carbon dioxide microbubbles through a catheter following conventional angiography in 41 patients with various gallbladder diseases. Three enhancement patterns were found; strong enhancement in the lesion from the periphery to the center was noted in patients with adenocarcinoma and benign polyp (type I), irregular partial enhancement at the margins of the lesion in those with adenosquamous carcinoma (type II), and internal regular enhancement in those with chronic cholecystitis, xanthogranulomatous cholecystitis and adenomyomatosis (type III). Pseudopolypoid lesion such as gallbladder debris showed no enhancement. US angiography may be useful in the differential diagnosis of gallbladder diseases, especially to differentiate the wall thickening type of gallbladder carcinoma from chronic cholecystitis or adenomyomatosis, and the pseudopolypoid lesion and fundal type of adenomyomatosis from benign polyp or polypoid-type carcinoma.

Adenocarcinoma↗
PubMed1994

Function of the minor duodenal papilla in pancreas divisum as determined by duodenoscopy using indigo carmine dye and a pH sensor.

OBJECTIVES: The objective of this study was to evaluate the function of the minor duodenal papilla and to investigate the relationship between the history of acute pancreatitis and individual dorsal pancreatogram findings and the minor papilla function in pancreas divisum. METHODS: Eight of the 21 patients with PD diagnosed by endoscopic retrograde cholangiopancreatography had a history of acute pancreatitis (group A), and 13 patients did not (group B). The reaction of pancreatic juice excreted via the minor papilla was evaluated after intravenous administration of secretin, by observing the repulsion of indigo carmine dye scattered on the surface of the minor papilla. RESULTS: The function of the minor papilla was classified into two types. In 12 patients, all of the pigment on the minor papilla was repelled within 5 min of secretin administration (type I), and in the remaining nine patients it was not (type II). After secretin administration, the pH of the minor papilla surface in type I was significantly higher than that in type II. There was no significant difference between the type I and type II patients in exocrine pancreatic function, as evaluated by a BT-PABA test. In the group A patients, the rate of occurrence of dorsal duct dilation (including changes of the terminal shape) was significantly greater than in the group B patients. The function of the minor papilla in the group A patients was significantly worse than in the group B patients. Outflow obstruction of pancreatic group B patients. Outflow obstruction of pancreatic juice, i.e., "relative stenosis of the minor papilla," was considered to be present in the patients with type II papilla, and, therefore, the patients with type II papilla might suffer from acute pancreatitis resulting from poor drainage of pancreatic juice and excessive pressure in the dorsal duct. CONCLUSION: The finding that patients with PD have one of two types of minor papilla will be useful for understanding the condition and selecting the therapeutic plan for individual patients.

Acute Disease↗