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Biomedical subjects

H Toyoda

Publications and source records attributed to H Toyoda.

At least 55 records · Page 3Linked to original sources
PubMed2001

Quantitative comparison of the bolus and steady-state methods for measurement of cerebral perfusion and oxygen metabolism: positron emission tomography study using 15O-gas and water.

To evaluate a new simplified bolus method for measurement of cerebral perfusion and metabolism, the parametric images with that method were compared with those obtained from the conventional steady-state method with 15O-gas. The new method also provided images of arterial blood volume (V0), which is a different parameter from cerebral blood volume (CBV) obtained using a C15O technique. Seven healthy volunteers and 10 patients with occlusive cerebrovascular diseases underwent positron emission tomography (PET) scans with both methods. Three-weighted integration was applied to calculate regional cerebral blood flow (rCBF) and regional cerebral metabolic rate of oxygen (rCMRO2) in the bolus method. Global and regional CBF and CMRO2 in volunteers were compared between the two methods and used as control data. Regional values in patients also were evaluated to observe differences between the bilateral hemispheres. Both rCBF and rCMRO2 were linearly well correlated between the two methods, although global difference in CMRO2 was significant. The difference in each parametric image except for V0 was significant between the bilateral hemispheres in patients. The bolus method can simplify oxygen metabolism studies and yield parametric images comparable with those with the steady-state method, and can allow for evaluation of V0 simultaneously. Increase in CBV without a change in V0 suggested the increase might mainly be caused by venous dilatation in the ischemic regions.

Adult↗
PubMed2001

Effects of acetazolamide on cerebral blood flow, blood volume, and oxygen metabolism: a positron emission tomography study with healthy volunteers.

To evaluate changes in cerebral hemodynamics and metabolism induced by acetazolamide in healthy subjects, positron emission tomography studies for measurement of cerebral perfusion and oxygen consumption were performed. Sixteen healthy volunteers underwent positron emission tomography studies with 15O-gas and water before and after intravenous administration of acetazolamide. Dynamic positron emission tomography data were acquired after bolus injection of H2[15O] and bolus inhalation of 15O2. Cerebral blood flow, metabolic rate of oxygen, and arterial-to-capillary blood volume images were calculated using the three-weighted integral method. The images of cerebral blood volume were calculated using the bolus inhalation technique of C[15O]. The scans for cerebral blood flow and volume and metabolic rate of oxygen after acetazolamide challenge were performed at 10, 20, and 30 minutes after drug injection. The parametric images obtained under the two conditions at baseline and after acetazolamide administration were compared. The global and regional values for cerebral blood flow and volume and arterial-to-capillary blood volume increased significantly after acetazolamide administration compared with the baseline condition, whereas no difference in metabolic rate of oxygen was observed. Acetazolamide-induced increases in both blood flow and volume in the normal brain occurred as a vasodilatory reaction of functioning vessels. The increase in arterial-to-capillary blood volume made the major contribution to the cerebral blood volume increase, indicating that the raise in cerebral blood flow during the acetazolamide challenge is closely related to arterial-to-capillary vasomotor responsiveness.

Acetazolamide↗
PubMed2001

Fatal bleeding from a residual vein at the esophageal ulcer base after successful endoscopic variceal ligation.

Endoscopic variceal band ligation (EVL) is now one of the accepted treatment options for esophageal varices, and the safety of this procedure has been proved. However, we experienced a patient who had a fatal massive bleeding after successful EVL for ruptured esophageal varix. Postmortem study revealed a residual vein at the base of the esophageal ulceration associated with the ligation, which was believed to be the site of the fatal bleeding. His platelet counts and prothrombin time were not very impaired. Our case indicates that fatal massive bleeding can occur in patients after successful EVL without specific risk factors and indicates the importance of the awareness of the possibility of these complications.

Esophageal and Gastric Varices↗
PubMed2001

Endosonographic images of low-grade lymphoma of mucosa-associated lymphoid tissue after radiotherapy.

Recently, radiation therapy has been reported to be effective in patients with low-grade lymphoma of mucosa-associated lymphoid tissue (MALT) of the stomach. We describe changes in endoscopic ultrasonographic (EUS) findings after radiation therapy in a patient with low-grade gastric MALT lymphoma. Endoscopic ultrasonography initially showed enlargement of regional lymph nodes and diffuse thickening of the second and third mural layers in the gastric body. Two months after the end of radiation therapy, EUS showed hypoechoic changes in the third layer that corresponded to the ulcer scar but no wall thickening or lymph node enlargement. The hypoechoic changes were thought to reflect inflammatory change. We conclude that EUS is useful for assessing the response to radiation therapy in patients with low-grade gastric MALT lymphoma.

Aged↗
PubMed2001

Interferon responsiveness in patients infected with hepatitis C virus 1b differs depending on viral subtype.

BACKGROUND: Genotype 1b of hepatitis C virus (HCV) comprises mainly three subtypes, each named for its geographic prevalence (worldwide, W; Japan, J; and not in Japan, NJ). AIM: To characterise the newly identified subtypes of genotype 1b and to review factors associated with response to interferon (IFN) for each subtype. PATIENTS: Chronic hepatitis patients (80 men and 41 women; mean age 48.5 years, range 20.7--69.3) with HCV genotype 1b (W type, n=41; J type, n=38) or genotype 2a (n=42) were treated according to the same IFN protocol. Forty four patients (36.4%) negative for serum HCV RNA six months after cessation of treatment were considered complete responders. METHODS: Factors associated with complete response were investigated. RESULTS: Genotype 2a patients had lower viral loads (odds ratio 0.11 (95% confidence intervals (CI) 0.049--0.256)) and a better IFN response (odds ratio 0.25 (95% CI 0.117--0.552)) than genotype 1b patients whereas W type and J type patients had similar viral loads and responses to IFN. IFN response in W type patients was associated with female sex (odds ratio 0.23 (95% CI 0.055--0.983)) and low viral load (odds ratio 84.00 (95% CI 14.04--502.6)) whereas response in J type patients was related to transfusion history (odds ratio 7.20 (95% CI 1.443--35.91)), low viral load (odds ratio 117.0 (95% CI 17.82--768.3)), and genetic mutation in the interferon sensitivity determining region of the virus (odds ratio 0.08 (95% CI 0.013--0.553)). Multivariate analysis found low viral load (odds ratio 64.19 (95% CI 14.66--281.06)) to be the only significant independent factor associated with IFN response. CONCLUSIONS: Factors associated with IFN responsiveness in HCV infection differ with viral subtype.

Adult↗
PubMed2001

Effect of the dose and duration of interferon-alpha therapy on the incidence of hepatocellular carcinoma in noncirrhotic patients with a nonsustained response to interferon for chronic hepatitis C.

OBJECTIVE: We evaluated the effect of dose and duration of treatment with interferon (IFN)-alpha on the incidence of hepatocellular carcinoma (HCC) after IFN treatment in patients with chronic hepatitis C. METHODS: A total of 291 noncirrhotic patients with chronic hepatitis C without hepatitis B virus coinfection in whom hepatitis C virus (HCV) was not eradicated by IFN-alpha therapy were retrospectively analyzed. The incidence of HCC after IFN therapy was compared according to the total dose or duration of treatment. RESULTS: Patients were followed up for 6-117 months after the end of IFN treatment. The duration of IFN treatment (< or =24 vs. >24 weeks) had no effect on the incidence of HCC. However, the incidence of HCC was significantly lower in patients who received >500 million units of IFN as a total dose than in patients who received < or =500 million units of IFN (p = 0.0480), and the total dose of IFN (>500 million units) was an independent factor affecting the incidence of HCC (p = 0.0405). In addition, when focusing on patients whose histology was F2 or F3 before IFN treatment, the suppressive effect of the total dose of IFN (>500 million units) was emphasized (p = 0.0049 in generalized Wilcoxon test and p = 0.0178 in multivariate analysis). CONCLUSIONS: Patients with chronic hepatitis C should receive more than 500 million units of IFN when IFN is used to decrease the incidence of subsequent HCC.

Adolescent↗
PubMed2001

[An exploratory positioning analysis: three-mode multivariate analysis for semantic differential data].

The purpose of this study was to propose an exploratory positioning analysis method based on a three-mode multivariate statistical model for analyzing semantic differential (SD) data. This new method can be easily implemented by using a structural equation modeling (SEM) program such as LISREL and CALIS, because the mean structure and covariance structure of this method are expressed as submodels of SEM. Two necessary conditions for checking identifiability of this model are shown. It is also shown that this model is scale equivariant for SD data.

Humans↗
PubMed2001

[A confirmatory positioning analysis: a multivariate analysis for finding change of image and evaluation of cognitive map].

A confirmatory approach to the positioning method (Toyoda, 2001) that can be used for analyzing three-mode multivariate data measured by the semantic differential (SD) method is considered. Two examples of the confirmatory method are given to demonstrate the applicability of the model. The first is a method to test the difference of image, between an experimental group and a control group. The second is a method to evaluate cognitive maps that are drawn subjectively. The conventional standard methods are not capable of solving these problems.

Cognition↗
PubMed2001

Characteristics and course of small hepatocellular carcinomas in patients with hepatitis C virus types 1 and 2.

The associations between types of HCV and tumor characteristics and recurrence and survival after treatment of small HCC were investigated. Viral genotype-specific antibodies were measured in sera obtained at the time of diagnosis of HCC, in 92 patients with HCC < or = 2 cm in diameter who were treated between 1990 and 1998. The degrees of tumor differentiation and angiographically-evaluated hypervascularity were compared between patients infected with HCV type 1 and those with type 2. Survival, time to recurrence, and patterns of recurrence after initial treatment also were compared. On pathologic evaluation, 6 of 21 HCC (28.6%) in patients with HCV type 2 were well-differentiated, whereas 28 of 48 HCC (58.3%) in patients with HCV type 1 were well-differentiated (P = 0.0229). HCC in patients with HCV type 2 showed hypervascularity more frequently than HCC in patients with HCV type 1, with tumor staining evident by digital subtraction arteriography in 17 of 22 patients with HCV type 2 (77.3%) vs. 20 of 50 in patients with HCV type 1 (40.0%, P = 0.0036). Survival and overall recurrence rates were similar in patients infected with HCV type 1 and with HCV type 2 (P = 0.5537). In the analyses of patterns of recurrence, recurrences in patients infected with HCV type 2 were relatively more likely to be intrahepatic metastases (P = 0.0342), that was closely related to the differentiation of HCC. Multicentric occurrence of HCC was a more frequent type of recurrence in patients with HCV type 1 (P = 0.1619), and infection of HCV type 1 was an independent factor for multicentric occurrence in multivariate analysis (P = 0.0021). In HCC < or = 2 cm in diameter, HCV type 2 is associated with more progression of HCC than HCV type 1, whereas patients with HCV type 1 may be at higher risk for multicentric HCC occurrence after the treatment of HCC.

Aged↗
PubMed2001

Japan-specific subtype of hepatitis C virus genotype 1b, J subtype, has relatively low pathogenicity.

The prognostic implication of viral genotype 1b for hepatitis C virus (HCV) infection has been controversial, possibly due to the pathogenetic heterogeneity of genotype 1b. We analyzed two newly delineated subtypes of HCV genotype 1b subtypes with respect to progression of liver disease. Patients with chronic HCV 1b infection (113 total, including 18 with chronic persistent hepatitis, 60 with chronic active hepatitis, 19 with cirrhosis, and 16 with hepatocellular carcinoma with cirrhosis) were studied to elucidate the factors associated with progression of liver disease. Factors evaluated included sex, age at diagnosis, blood transfusion history, and HCV genotype 1b subtype (W subtype or J subtype). W subtype was identified more often in association with chronic active hepatitis than with chronic persistent hepatitis (P = 0.0089), and more often in patients with cirrhosis than in those without (P = 0.0044). The age-, sex-, and transfusion history-adjusted odds ratios with respect to histological activity and presence of cirrhosis for W subtype compared to J subtype were 6.966 (1.856 to 26.145) and 6.397 (1.506 to 27.179), respectively. Age at diagnosis was the most important risk factor for predicting development of cirrhosis and carcinoma. In conclusion, the W subtype of HCV 1b is associated closely with histologically active disease and development of cirrhosis, whereas the Japan-specific J subtype has relatively low pathogenicity. HCV genotype 1b, therefore, is heterogeneous in its pathogenicity.

Adult↗
PubMed2001

Determination of lipid-bound sulfate by ion chromatography and its application to quantification of sulfolipids from kidneys of various mammalian species.

A variety of procedures have been developed for determining the sulfate ester content of various biomolecules. Ion chromatography (IC), that is, quantitation of ionic substances by ion conductimetry after separation by anion-exchange chromatography, has been increasingly utilized for the determination of inorganic sulfate in clinical and environmental samples. We adopted suppressed-mode IC to the determination of lipid- or glycolipid-bound sulfate released by acid hydrolysis and found that it has the advantage of increased precision for wide concentration ranges (30 pmol to approximately micromol) and lack of interference from other lipids. To minimize deterioration of the separation column, the lipophilic constituents in the acid hydrolysate were removed by a two-phase partition system of chloroform-methanol-water. The inorganic sulfate was quantitatively extracted into the aqueous phase by replacing water with an alkaline buffer. By this method, the concentration of sulfolipids was determined in the kidney of mammals with various body mass. Sulfolipids were more concentrated in the kidney of smaller animals, which have higher maximum urine concentrating activity per gram of body mass, supporting the hypothesis of the function of sulfolipids as an ion barrier on the luminal surface of renal tubules.

Animals↗
PubMed2000

Immunologic dynamics in hemophiliac patients infected with hepatitis C virus and human immunodeficiency virus: influence of antiretroviral therapy.

Infection with hepatitis C virus (HCV) or human immunodeficiency virus (HIV) or both is common in hemophiliac patients due to putative transmission through clotting factor concentrates. Recently, highly active antiretroviral therapy (HAART) has been found to markedly improve viremia and immunologic parameters in patients infected with HIV. This report considers interactions between these viral infections, the immune system, and antiretroviral therapy. A total of 130 male hemophiliac patients were grouped according to type of viremia (HCV, HIV, both, or neither). Along with 30 healthy men age-matched to viremic patients, these groups were compared with respect to viral load and immunologic parameters. Thirty-five patients treated as above for HIV were serially followed up. HCV infection was associated with reduced peripheral B-cell and CD4(+)-cell counts and with increased serum IgG and IgM levels, whereas HIV infection was associated with reduced peripheral CD4(+)-cell counts and increased serum IgG and IgA levels. In patients with both viruses, HCV and HIV RNA load correlated inversely with peripheral B-cell and CD4(+)-cell counts, respectively. HAART reduced levels of both viruses in the blood. Of the 25 patients with both viruses, HAART eliminated HCV in 2. In conclusion, immunologic dynamics differed between hemophiliac patients infected with HCV, HIV, or both. The relative dynamics of HCV viral load, peripheral B-cell count, and serum IgM level were similar to those of HIV viral load, CD4(+)-cell count, and serum IgA. (Blood. 2000;96:4293-4299)

Adolescent↗
PubMed2000

Abnormalities of primitive myeloid progenitor cells expressing granulocyte colony-stimulating factor receptor in patients with severe congenital neutropenia.

To define the basis for faulty granulopoiesis in patients with severe congenital neutropenia (SCN), the expression of granulocyte colony-stimulating factor receptor (G-CSFR) in primitive myeloid progenitor cells and their responsiveness to hematopoietic factors were studied. Flow cytometric analysis of bone marrow cells based on the expression of CD34, Kit receptor, and G-CSFR demonstrated a reduced frequency of CD34(+)/Kit(+)/ G-CSFR(+) cells in patients with SCN. The granulocyte-macrophage colony formation of CD34(+)/Kit(+)/G-CSFR(+) cells in patients was markedly decreased in response to G-CSF alone and to the combination of stem cell factor, the ligand for flk2/flt3, and IL-3 with or without G-CSF in serum-deprived semisolid culture. In contrast, no difference in the responsiveness of CD34(+)/Kit(+)/G-CSFR(-) cells was noted between patients with SCN and subjects without SCN. These results demonstrate that the presence of qualitative and quantitative abnormalities of primitive myeloid progenitor cells expressing G-CSFR may play an important role in the impairment of granulopoiesis in patients with SCN. (Blood. 2000;96:4366-4369)

Antigens, CD34↗
PubMed2000

Measurement of the decay amplitudes of B0 --> J/psiK*0 and B(s)(0) --> J/psistraight phi decays

An angular analysis of B0-->J/psiK(*0) and B(0)(s)-->J/psistraight phi has been used to determine the decay amplitudes with parity-even longitudinal ( A0) and transverse ( A( parallel)) polarization and parity-odd transverse ( A( perpendicular)) polarization. The measurements are based on 190 B0 and 40 B(0)(s) candidates obtained from 89 pb(-1) of &pmacr;p collisions at the Fermilab Tevatron. The longitudinal decay amplitude dominates with |A0|(2) = 0.59+/-0. 06+/-0.01 for B0 and |A0|(2) = 0.61+/-0.14+/-0.02 for B(0)(s) decays. The parity-odd amplitude is found to be small with |A( perpendicular)|(2) = 0.13(+0.12)(-0.09)+/-0.06 for B0 and |A( perpendicular)|(2) = 0.23+/-0.19+/-0.04 for B(0)(s) decays.

Journal Article↗