Biomedical subjects

M Koyama

Publications and source records attributed to M Koyama.

334 records · Page 19Linked to original sources

PubMedDate not supplied

Effects of long-term treatment with alpha-glucosidase inhibitor on the peripheral nerve function and structure in Goto-Kakizaki rats: a genetic model for type 2 diabetes.

BACKGROUND: Continuous hyperglycemia is implicated in the pathogenesis of chronic diabetic complications. It is not well known, however, how and to what extent the development of neuropathy is inhibited by blood glucose control in subjects with Type 2 diabetes. We investigated therefore the effects of an alpha-glucosidase inhibitor (voglibose; Vg) on neuropathic changes in diabetic Goto-Kakizaki (GK) rats, a genetic model for Type 2 diabetes. METHODS: Twelve week-old male GK rats were given a diet containing Vg (50 ppm) for 24 weeks and monitored for blood glucose, glycated hemoglobin, motor nerve conduction velocity (MNCV). At the end of the administration period (Na(+), K(+))-ATPase activity and the structure of the peripheral nerves were examined. Age- and sex-matched normal Wistar rats were treated similarly and served as controls. RESULTS: GK rats showed fasting hyperglycemia after 8 weeks of age, and Vg treatment significantly lowered levels of blood glucose and glycated hemoglobin. Slowing of MNCV to 80% of normal control levels was detected in GK rats. Vg treatment inhibited this delay by 24% at 24 weeks and 57% at 36 weeks of age. Nerve (Na(+), K(+))-ATPase activity was reduced to 80% of normal control levels in GK rats and was restored by Vg treatment. Teased fiber studies revealed a higher incidence of fibers with paranodal, segmental demyelination and axonal degeneration in GK rats. Vg treatment significantly inhibited the development of these nerve-fiber abnormalities. CONCLUSIONS: Lowering of high blood glucose levels achieved by the use of Vg in GK rats improved MNCV and demyelinative nerve changes with restoration of (Na(+), K(+))-ATPase activity.

Animals↗

PubMedDate not supplied

Localization of three subtypes of Fc gamma receptors in human placenta by immunohistochemical analysis.

We investigated the localization of the three subtypes of (Fc gamma R) in the normal human placenta using immunohistochemical and immunocytochemical techniques with specific monoclonal antibodies. The analysis revealed that Fc gamma RI was expressed on Hofbauer cells, that Fc gamma RII was expressed on Hofbauer cells and endothelial cells of fetal vessels, while Fc gamma RIII was expressed on trophoblasts, especially syncytiotrophoblasts. Moreover, we demonstrated that the expression of Fc gamma RI and Fc gamma RII on Hofbauer cells and endothelial cells of the fetal vessels in the 1st trimester placenta was different from that in the 3rd trimester placenta. These results, therefore, indicate that the three subtypes of Fc gamma R in the human placenta may contribute to maintenance of placental functions, because each Fc gamma R molecule displays unique biological functions similar to those on leukocytes.

Animals↗

PubMedDate not supplied

Radioimmunoassay for ubenimex in human serum.

Anti-ubenimex antibody was produced by immunization of rabbits with ubenimex-bovine serum albumin (BSA) conjugate which was synthesized by coupling ubenimex directly to BSA using 1-ethyl-3-(3-dimethyl-aminopropyl)carbodiimide. The resulting antibody exhibited little cross-reactivity with p-hydroxyubenimex or (2S,3R)AHPA, (2S,3R)-3-amino-2-hydroxy-4-phenylbutanoic acid present in human serum as metabolites. Ubenimex in human serum could be measured selectively without prior drug extraction and purification. The standard curve prepared using the present assay method gave good linearity in the range 0.25-25 ng per assay tube. The detection limit was 125 pg per assay tube. The concentrations of ubenimex in human serum determined by the present method were in good agreement with those obtained by GC-SIM. The present method with its high sensitivity and specificity may be a valuable tool for the study of the pharmacokinetics of ubenimex.

Aminopeptidases↗

PubMedDate not supplied

Measurement of diagnostic x-ray spectra using a silicon photodiode.

Diagnostic x-ray spectra (66-103 kV, 1-2 mA) were measured without pinhole collimator or liquid nitrogen cooling by using a silicon p-i-n photodiode. An x-ray count rate was low (approximately 400 photons/s) at distances of 2-3 m away from an x-ray target, because the i layer of the photodiode was very small (1.5 mm2 in area and 75 microns in thickness). The junction reverse current of the photodiode was 50-70 pA at room temperature and energy resolution for 59.5-keV gamma rays was 2.0 keV (full width at half-maximum), which was limited by the electric noise of a preamplifier. Measured spectra were corrected for detector distortion. The corrected spectra were similar to those determined with a Ge detector. The i-layer thickness of the photodiode was an important parameter for the correction. In particular, when the thickness was thin, the fraction of photoelectron escape became large; this fraction was estimated analytically for various i-layer thicknesses. The angular dependence of the full-energy peak efficiency was measured; for the photons whose energies were above 17.8 keV the angular dependence was isotropic except for angles greater than 60 degrees off the photodiode axis. This method is therefore applicable to the measurement of scattered x rays.

Radiography↗

PubMedDate not supplied

Effects on health of dietary supplementation with 100 mg d-alpha-tocopheryl acetate, daily for 6 years.

To evaluate the clinical antioxidant effects of vitamin E, 161 healthy volunteers aged 39 to 56 years, were given 100 or 3 mg of d-alpha-tocopheryl acetate orally daily for 6 years using a randomized, double-blind design. Among the 147 volunteers who qualified for the analysis, seven of the 73 volunteers receiving 3 mg d-alpha-tocopheryl acetate daily and none of the 74 volunteers receiving 100 mg had coronary disorders including myocardial damage (P < 0.02). ST or T wave abnormalities on electrocardiograms were considered to indicate coronary disorders (four volunteers). The mean serum total tocopherol (TOC) concentration in the 100-mg group was significantly higher than that in the 3-mg group 6 months after the start of the study, and this raised value was maintained throughout the study; the level in the 3-mg group did not change significantly from the baseline value. The low-density lipoprotein cholesterol/total TOC ratio, a parameter of the inhibition of peroxidation of low-density lipoprotein cholesterol, was the only serum lipid parameter that was significantly different, at baseline, in the volunteers with coronary disorders compared with the others. These findings indicate that long-term supplementation with 100 mg tocopheryl acetate daily may prevent the early stages of coronary atherosclerosis by decreasing peroxidation of low-density lipoprotein cholesterol.

Adult↗

PubMedDate not supplied

Assessment of a continuing education evaluation framework.

This study analyzes a systems model for evaluation research of continuing education (CE) and reports on the result of a quasi-experimental study of a stoma care CE program. Holzemer's conceptual framework for evaluating CE consisting of the learner, setting, and program along with a systems model was used as an organizing framework. A quasi-experimental design (n = 24 experimental group and n = 27 control group) was used to evaluate the impact of the CE program. Pre- and post-tests of participants' knowledge and skills of stoma care were evaluated. Participants' satisfaction with the course was surveyed by questionnaire during the course, on completion and four months after the course. No significant differences were found between the two groups. The revised framework included the concept of needs assessment and the impact of the CE program on patient care.

Adult↗

PubMedDate not supplied

A pilot study of paclitaxel and carboplatin for recurrent ovarian cancer.

Combination chemotherapy with paclitaxel and platinum is the most effective regimen for advanced ovarian cancer. Second-line chemotherapy with paclitaxel (135 mg/m2, 24 h) and carboplatin (AUC 5-6) is also effective for patients who relapse on the same regimen after 6 months or more. However, it has been shown that the same efficacy and less myelosuppression can be achieved with a 3-h infusion of paclitaxel (135 mg/m2), and that dose intensification of carboplatin to an AUC values larger than 4-6 is meaningless. Therefore, we decided to conduct a pilot study of paclitaxel (135 mg/m2, 3 h) and carboplatin (AUC 4-5) for ovarian cancer patients who had relapsed or were resistant to a platinum-containing regimen without paclitaxel. Eligibility criteria included patients with relapsed or resistant ovarian cancer (no specified duration from prior therapy), age 16-75 years, with performance status 0-2, and adequate bone marrow, renal, and hepatic function. Paclitaxel was administered at a fixed dose of 135 mg/m2 followed by one of two carboplatin doses (AUC 4 or 5). Specific doses were alternated between individual patients by the order in which they entered the study. Treatment was repeated every 3 weeks, and more than 4 cycles were administered. A total of 11 patients were enrolled. Carboplatin was administered to 6 patients at an AUC of 4 and to 5 patients at an AUC of 5. The age of patients ranged from 18 to 65 years (median: 54). Other patient data (number of patients): serous (8), non serous (3), patients with measurable disease (9), assessable/CA 125 (3), study drug administration less than 6 months after prior therapy (5), study drug administration 6 months or more after prior therapy (6). Response was defined by CT and CA 125 level. CR was observed in 25% (2/8), PR in 38% (3/8), NC in 25% (2/8), and PD in 13% (1/8) of the patients. The response rate with assessable patients was 100% (3/3), and the overall response rate was 73% (8/11). Two patients with grade 1 tachycardia and grade 4 thrombocytopenia, respectively, refused further treatment after 2 cycles. No other patients experienced grade 4 hematologic toxicity or grade 3 non-hematologic toxicity. The median survival duration after paclitaxel and carboplatin therapy was 21+ months (6-26+ months). This regimen is easy to manage in heavily pretreated patients and seems to have good efficacy. To further assess the efficacy, a phase II study is needed.

Adenocarcinoma↗

PubMedDate not supplied

Pitfalls in the interpretation of multidetector-row helical CT images at window width and level setting for lung parenchyma.

This article describes pitfalls in the interpretation of multidetector-row helical CT (MDCT) images at the window width and level settings for lung parenchyma. On MDCT, linear artifacts, which look like black and white linear densities and are called "hurricane artifacts," radiate out from objects that have very different densities from their neighbors. For the evaluation of fine parenchymal details, a low table speed/slice collimation should be used. In fact, axial (step and shoot) scanning may be more effective for the evaluation of fine details. Since artifacts from vessels highly enhanced by contrast medium cause data blackout in the surrounding areas at high table speed/slice collimation, pulmonary parenchyma in such situations should be evaluated with unenhanced CT. Although multidetector-row helical CT is a promising tool for the evaluation of lung parenchyma, it is important to identify its shortcomings due to artifacts when interpreting images at the window width and level settings for lung parenchyma and to apply the appropriate methods for eliminating such artifacts.

Artifacts↗

PubMedDate not supplied

Evaluation of image quality and spatial resolution of low-dose high-pitch multidetector-row helical high-resolution CT in 11 autopsy lungs and a wire phantom.

PURPOSE: The aim of this study was to evaluate whether low-dose high-pitch (6:1) multidetector-row helical high-resolution CT is appropriate for the evaluation of various pulmonary abnormalities, including faint opacities. METHODS: Eleven autopsy lungs were scanned with a multidetector-row CT scanner using 2.5 mm x 4 beam collimation, effective slice thickness 3 mm, 6:1 pitch, 0.8 second gantry rotation speed, 20 cm Display FOV, high spatial frequency (bone) algorithm, and various radiation doses (120 kVp; 160, 80, 40, 24, and 8 mAs). The image quality of each CT set was assessed as adequate or inadequate for diagnosis by two independent observers. In addition, a wire phantom was scanned with the same parameters in order to describe the MTF curves. RESULTS: There was excellent agreement between the observers for the evaluation of image quality (kappa statistic, 0.84). The ratio of images evaluated as inadequate for 8 mAs and 24 mAs was significantly higher than that for 160, 80, and 40 mAs (p<0.01: chi-square test). MTF curves of both 8 and 24 mAs were significantly inferior to those of 40, 80, and 160 mAs (p<0.0 1, Friedman test), while the MTF curve of 40 mAs was relatively inferior to that of 160 mAs (p<0.05, Friedman test). CONCLUSION: More than 40 mAs in combination with 120 kVp is preferable for the evaluation of details of lung parenchyma by high-pitch. multidetector-row helical high-resolution CT.

Autopsy↗

PubMedDate not supplied

Hepatocellular carcinoma in primary biliary cirrhosis: a case report and review of the Japanese literature.

We present a 66 year-old woman in the cirrhotic stage of primary biliary cirrhosis (PBC), who developed hepatocellular carcinoma (HCC). All serological tests for hepatitis B virus (HBV) and hepatitis C virus (HCV) were negative. We surveyed 16 reported cases (13 females and 3 males) of PBC associated with HCC in Japan. The presence of HCV RNA was determined by the polymerase chain reaction in all of the patients, 3 of whom (19%) were HCV RNA-positive. Although patients with PBC rarely develop HCC, it is suggested that HCV infection may play a minor role in the development of HCC in Japanese patients with PBC.

Aged↗