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Biomedical subjects

K Masuda

Publications and source records attributed to K Masuda.

At least 235 records · Page 13Linked to original sources
PubMed1997

Differentiating between multiple system atrophy and Parkinson's disease by positron emission tomography with 18F-dopa and 18F-FDG.

Both the striatal 18F-dopa uptake and brain glucose metabolism were studied by PET with 6-L-[18F]fluorodopa (FD) and [18F]fluorodeoxyglucose (FDG) in 9 patients with multiple system atrophy (MSA) and 15 patients with idiopathic Parkinson's disease (PD). Five of the 9 MSA patients were diagnosed as having olivopontocerebellar atrophy, whereas 2 had striatonigral degeneration and 2 demonstrated Shy-Drager syndrome. The FD uptake ratios to the occipital cortex in the MSA patients at 120 min after the administration of FD were 2.07 +/- 0.31 (mean +/- SD) and 1.96 +/- 0.29 in the caudate and the putamen, respectively, and decreased compared to those in the controls (2.72 +/- 0.11, 2.71 +/- 0.10). The same ratios in the PD patients were 2.07 +/- 0.36 and 1.74 +/- 0.24, respectively, which also decreased, but the decreased uptake in the putamen was more prominent. The caudate-putamen index (CPI)(%), which was calculated by a formula based on the difference in the uptakes in the caudate and putamen divided by the caudate uptake, indicated 5.6 +/- 4.6 in the MSA patients and 14.8 +/- 5.4 in the PD patients. The CPI for all PD patients was more than 7.0, which was the mean + 2SD for the controls, but the CPI for 3 MSA patients was more than 7.0 (accuracy: 88%). The glucose metabolic rates for each region in the PD patients showed no difference from the normal controls. The frontal and the temporal cortical glucose metabolism and the caudate, the putaminal, the cerebellar and the brainstem glucose metabolism in the MSA patients decreased significantly in comparison to those in the controls. But, as the glucose metabolic rates in such regions of each patient overlapped in the two groups, the accuracy of the FDG study for differentiation was lower than that of the FD study. The putaminal glucose metabolic rates, for example, in 3 PD patients were less than 6.8 (mg/min/100 ml), which was the mean-2SD for the controls, while those in 3 MSA patients were more than 6.8 (accuracy: 75%). In addition, the combination of these two methods slightly improved the accuracy. The glucose metabolism is useful for evaluating the regional metabolic activity of the brain, and the FD study, which is specific to the dopamine system, seems to be more useful for differentiating between MSA and PD.

Adult↗
PubMed1997

Acute suppurative perithyroiditis: MR findings.

We report the MR findings in two cases of acute suppurative perithyroiditis. MR has the advantages over other imaging modalities of being able to distinguish areas of inflammation from adjacent normal tissue and of allowing imaging in planes which more accurately demonstrate the extent of the lesion. MR imaging is one of the most useful methods to evaluate this entity.

Acute Disease↗
PubMed1997

Morphological adaptation of capillary network in compensatory hypertrophied rat plantaris muscle.

The aim of this study was to examine the morphological adaptation of the capillary network in hypertrophied plantaris muscles by examining both capillary numbers and luminal circumferences. Hypertrophy of the plantaris muscle was induced by myectomy of the gastrocnemius muscle. This hypertrophy was characterised by increases in muscle mass and fibre cross-sectional area. All capillary parameters were determined using morphometric methods in perfusion-fixed plantaris muscle. Increased capillary-to-fibre ratio was observed in the overloaded plantaris muscle while no change was observed in the capillary luminal circumference. No differences were observed in the capillary density and the capillary-to-fibre perimeter ratio of the normal and the hypertrophied plantaris muscle. These results indicated that chronic overload-induced neocapillarization, but not enlargement of capillary luminal circumference, contributed to the prevention of decreases in the capillary-to-fibre perimeter ratio in the plantaris muscle in the hypertrophied process.

Adaptation, Physiological↗
PubMed1997

Colour Doppler sonography of breast masses: a multiparameter analysis.

OBJECTIVE: To evaluate signals from breast lesions on both colour and spectral Doppler US, and to correlate findings with angiographic and histopathological features including microvessel density. MATERIALS AND METHODS: One hundred and sixteen breast lesions in 113 patients were evaluated with colour Doppler ultrasonography. Subjective and semi-quantitative assessment of colour signals as well as spectral Doppler analysis were performed and compared. Comparison of colour Doppler features with angiographic and histopathological findings were also carried out. RESULTS: Subjective evaluation revealed that colour signals were more commonly found in malignant (89%) than benign (56%) lesions. Malignant lesions demonstrated a more elaborate vascular network (51%) compared to 12.5% in benign lesions. Spectral Doppler analysis revealed slightly higher specificity values for the pulsatility and resistivity indices, respectively, but lower sensitivity and accuracy values compared to qualitative assessment. Colour Doppler patterns corresponded well with angiograhic images, however, the correlation between colour Doppler parameters and microvessel density was not significant. CONCLUSION: Despite the increased examination time required, spectral analysis does not appear to contribute significantly to the differentiation between malignant and benign breast tumours. Features such as the density, pattern and predominant site of colour signals may be more useful for the evaluation of breast lesions on colour Doppler imaging.

Adolescent↗
PubMed1997

Endoscopic submucosal tumorectomy for gastrointestinal submucosal tumors restricted to the submucosa: a new form of endoscopic minimal surgery.

BACKGROUND: Endoscopic minimally invasive therapy for submucosal tumors of the gastrointestinal tract by use of endoscopic ultrasound has not yet come into widespread use, and this technique has not been fully evaluated. We therefore investigated this method of treatment in patients with gastrointestinal submucosal tumors. METHODS: Forty-five patients with suspected gastrointestinal submucosal tumors (esophagus [5], stomach [1], duodenum [16], colon [23]) based on barium enema studies and endoscopy underwent endoscopic ultrasound by the water-filled or balloon method. The layer of origin and the internal echogenicity of the lesions were evaluated. After confirming that the tumors were submucosal, the lesions were resected using injection of physiological saline solution and electrocautery. RESULTS: Using a one-channel or two channel method, all tumors were completely resected without serious complications and the diagnosis was histologically confirmed. Ulceration at the site of resection healed within 2 to 4 weeks (mean 23 days) and there has been no local recurrence. CONCLUSIONS: Our technique of endoscopic submucosal tumorectomy appears to be a safe and useful diagnostic-cum-therapeutic procedure for gastrointestinal submucosal tumors.

Adult↗
PubMed1997

Positron emission tomography (PET) in Machado-Joseph disease.

Positron emission tomography studies on the regional cerebral glucose metabolism (rCMRglc) and 18F-fluorodopa (18F-Dopa) uptake were performed in 3 patients with Machado-Joseph disease (MJD), a dominantly inherited degenerative disease in the cerebellum, brainstem and basal ganglia. The rCMRglc in MJD was found to be significantly decreased in the cerebellum, brainstem, striatum and whole cerebral cortex in comparison to that in normal subjects. These results of rCMRglc were different from those for dominantly inherited olivopontocerebellar atrophy (dOPCA) or cerebellar cortical degeneration (CCD), however they were similar to those for sporadic olivopontocerebellar atrophy (sOPCA) and multiple system atrophy (MSA). The 18F-Dopa uptake in MJD was found to be significantly decreased in the putamen and relatively spared in the caudate, which was different from that of MSA. In addition, these results indicate that MJD showed a dysfunction, not only in the regions with apparent pathological involvement such as cerebellum, brainstem and nigro-striatal dopaminergic system, but also in the cerebral cortex and the striatum where no pathology could be observed using conventional morphological techniques.

Adult↗
PubMed1997

Clinical evaluation of UF-021 (Rescula; isopropyl unoprostone).

We have reviewed two Phase III clinical studies of isopropyl unoprostone conducted in Japan: a 12-week comparative study of 0.12% isopropyl unoprostone and 0.5% timolol, and a 52-week administration of two concentrations of isopropyl unoprostone in ocular hypertensive and primary open-angle glaucoma patients. These studies showed a similar ocular hypotensive effect of 0.12% isopropyl unoprostone to 0.5% timolol and a sustained ocular hypotensive effect of the drug for up to one year. Adverse reactions of isopropyl unoprostone were minor and similar to those of timolol. No pigmentary changes of the irides were noticed. In view of these results, isopropyl unoprostone seems to be a useful antiglaucoma medication.

Administration, Topical↗
PubMed1997

Prevention of infection in dental procedures.

The efficacy of a newly-developed anti-cross-contamination device in dentistry, the Air Flushing Clean System (AFCS), was tested under experimental and clinical conditions. In the experimental situation, a dental air turbine handpiece with or without AFCS was contaminated with two bacterial strains, Staphylococcus aureus FDA209P and Streptococcus mutants ATCC25175. After contamination with these bacteria, the handpieces were subjected to two disinfecting methods. Residual bacteria inside the handpiece or an air/water line were cultured and counted, and compared with controls. In this experiment, with AFCS but no dental vacuum suction, wiping of the handpiece with 70% ethanol gauze reduced the count of S. aureus by 99%. No bacterial contamination in the air/water line was detected after exchanging with an autoclaved handpiece. With AFCS and dental vacuum suction, bacterial contamination in the air/water line, as well as in the interior of the handpiece, was not detected. These results indicate that AFCS could reduce bacterial contamination within the air turbine handpiece more effectively than the conventional handpiece regardless of whether or not the dental vacuum suction was used.

Adult↗
PubMed1997

The sticking probability of a hydrogen atom on icy mantle.

In the present work, we investigate the sticking process of a hydrogen atom on the surface of dust grains. As a realistic model for the icy mantle of dust grains, we produced slab-shaped amorphous water ice with infinite area by classical molecular dynamics (MD) computational simulation using two-dimensional periodic boundary condition. The resulting amorphous water ice slabs at 10 K and 70 K were found to be in good agreement with the experimental high-density and low-density amorphous water ice, respectively. Then, we investigated the dynamical behaviors of an impinging H atom on the surface of it by MD simulations. The sticking probabilities of incident H atoms with several initial temperatures on 10 K and 70 K ice were obtained. It was found that most of H atoms colliding with the 10 K ice stuck on the surface of it. After having stuck, the impinging H atoms diffused on the surface of ice and became trapped in one of potential wells on the surface. The mobility of a H atom on the surface of the amorphous water ice was found to depend only upon the temperature of ice.

Computer Simulation↗
PubMed1997

Cerebral hemodynamics and metabolism in moyamoya disease--a positron emission tomography study.

We studied the cerebral blood flow (CBF), cerebrovascular response to hypercapnia, oxygen extraction fraction (OEF), metabolic rate for oxygen (CMRO2), blood volume (CBV) and transit time (TT: CBV/CBF) in Moyamoya disease using positron emission tomography (PET). The subjects consisted of 23 patients with Moyamoya disease, including eight pediatric and 15 adult patients. Among them, ten patients were examined both before and after surgery. The pediatric patients showed a marked increase in the CBV and a prolonged TT, especially in the striatum. The adult patients also showed a prolonged TT, but it was less prominent than that observed in pediatric patients, while the CBF remained at the level of the normal controls. The cerebrovascular response to hypercapnia was markedly impaired in both the pediatric and adult patients, which thus indicates a decrease in the hemodynamic reserve capacity. After surgery, the CBV, TT and cerebrovascular response to hypercapnia all improved, mainly in the temporal cortex where extracranial-intracranial (EC-IC) bypass surgery had been performed. In the striatum, the CBV also decreased, while the TT was shortened after surgery. A PET study was thus found to be useful for evaluating the cerebral hemodynamics in Moyamoya disease and monitoring the effect of surgery.

Adolescent↗
PubMed1997

Oxidative enzyme activity and soma size in motoneurons innervating the rat slow-twitch and fast-twitch muscles after chronic activity.

The effects of chronic activity induced by running training on the activity of the mitochondrial enzyme succinate dehydrogenase (SDH) and soma size in motoneurons innervating the slow-twitch soleus (SOL) and fast-twitch extensor digitorum longus (EDL) muscles were studied in rats using the retrograde neuronal tracer Nuclear Yellow. Rats were assigned to control and trained groups that were subjected to treadmill running for 10 weeks (2 h/day, 30 m/min, 5 days/week). After training, both SOL and EDL muscles showed clear adaptations (citrate synthase activity in the SOL muscle, and the fast-twitch oxidative-glycolytic fiber area of the EDL muscle increased significantly after training). The SDH activity of the motoneurons innervating both SOL and EDL muscles was unchanged by training. However, SOL motoneurons of trained rats had a significantly larger soma size and a significantly higher total SDH activity [SDH activity x soma size) than those of control. Total SDH activity was calculated to examine the absolute SDH protein content of the motoneurons. On the other hand, there was no difference in both soma size and total SDH activity of EDL motoneurons between the two groups. These data demonstrate that chronic activity has a considerably stronger impact on soma size and total oxidative enzyme activity of motoneurons innervating slow-twitch rather than fast-twitch muscles.

Animals↗
PubMed1997

Flow injection analysis for measurement of activity of matrix metalloproteinase-7 (MMP-7).

A simple and convenient method for measuring the activity of a recombinant human matrix metalloproteinase 7 (MMP-7, matrilysin) was developed by flow injection analysis (FIA). For this method, purified recombinant MMP-7 zymogen expressed in E. coli and the substrate peptide (MOCAc-Pro-Leu-Gly-Leu-A2pr(DNP)-Ala-Arg-NH2) were used. Following the incubation of substrate peptide with activated r-proMMP-7, the resulting fluorescent product peptide (MOCAc-Pro-Leu-GLY) was monitored with a fluorescence detector (lambda ex 328 mm, lambda em 393 mm) without chromatographic separation. In this FIA system, the analysis time is 2 min and the standard curve is linear from 5 to 100 pmol of the product peptide injected. In order to use this FIA system as a method for screening inhibitors against MMP-7, the effects of CaCl2, EDTA and of the tissue inhibitor of metalloproteinase-1, and -2, were tested. A synthetic PRCGXPD-containing peptide (BS-10) was also observed to inhibit MMP-7 activity, with an IC50 value of 104 microM. Thus, it was concluded that the activity of r-MMP-7 can be reliably measured by the proposed system. Furthermore, to confirm the utility of this FIA system as a screening method, the inhibitory activity of the MMP-related substance in Joro spider (Nephilia clavata) venom was measured by this method. This inhibitory activity was observed in an extract of a venom diluted 1000-fold. Thus, the FIA method is not only simple and quick, but also sensitive enough to screen and analyze the inhibitory properties of a large number of test compounds.

Enzyme Inhibitors↗
PubMed1997

Adaptation of myoglobin in compensatory hypertrophied rat muscle.

This study investigated the time course change of myoglobin concentration ([Mb]) in skeletal muscle during muscle hypertrophy in rats. Seven groups of Wistar rats (n = 7 per group) were examined. Compensatory hypertrophy of the plantaris muscle was induced by the bilateral ablation of the medial and lateral heads of the gastrocnemius muscle, and the effect of compensatory hypertrophy on the [Mb] of the plantaris muscle was examined at 7, 21 and 42 days post-ablation. The [Mb] expressed as mg g(-1) wet muscle weight tended to decline at 7 days post-ablation (-12.1%) and returned to the control level by 42 days post-ablation, as did the muscle protein concentration. However, the [Mb] expressed as mg g(-1) protein weight was not significantly different between the ablation and control groups throughout the experimental period. The estimated value of absolute Mb content in the whole plantaris muscle was significantly increased by 28.4% (P < 0.01) at 42 days post-ablation compared with the age-matched controls. Therefore, the longer period of compensatory activity allowed the Mb to increase in its absolute content, although the [Mb] did not exceed the level of control muscle. The capacity of facilitated oxygen diffusion and oxygen storage by Mb in the muscle cells will not change even when muscle enlargement takes place.

Animals↗
PubMed1997

Human T-cell lymphotropic virus type 1 can infect primary rat retinal glial cells and induce gene expression of inflammatory cytokines.

PURPOSE: To examine whether or not retinal glial cells can be infected by human T-cell lymphotropic virus type 1 (HTLV-1) and test the possibility that HTLV-1-infected retinal glial cells are involved in the pathogenesis of HTLV-1 uveitis (HU). METHODS: We tested infection of HTLV-1 by a standard coculturing method using WKAH rat retinal glial cells and irradiated MT-2, a human T cell line that produces HTLV-1. Infection was confirmed by detecting the integrated HTLV-1 provirus, using polymerase chain reaction (PCR), viral gene expression, using reverse transcriptase-PCR (RT-PCR) and HTLV-1 p19 ELISA, and by identifying the HTLV-1-infected glial cells by immunofluorescence cytochemistry and in situ hybridization. Changes in cytokine gene expression were studied by RT-PCR. RESULTS: Using a semiquantitative PCR of HTLV-1 provirus sequence, we found that 2.6% of the retinal glial cells were infected at 3 days after infection, followed by a gradual decrease in the percentage with an extended period of culture up to 4 weeks. This time course of infection was also verified by RT-PCR and ELISA studies that detect viral mRNA expression and protein production, respectively. Expression of HTLV-1 gag protein and tax mRNA was detected in a part of glial cells by indirect immunofluorescence cytochemistry and in situ hybridization, respectively. RT-PCR analysis of cytokine gene expression revealed that gene expression of IL-6, CINC-1 (Gro, KC), and TNF-alpha were induced in these cells, with a peak at 3 weeks after infection. CONCLUSION: These results provided supportive evidence for the theory that the infection of retinal glial cells by HTLV-1 and subsequent production of inflammatory cytokines could be one contributing factor for the development of the unique clinical features of HU. A better understanding of the specific roles of the inflammatory cytokines in the pathogenesis of HU would be beneficial in the treatment and control of this disease.

Animals↗
PubMed1997

Distribution of blastodermal cells transferred to chick embryos for chimera production using windowed eggs.

1. To improve the production of chimeras, the distribution of donor blastodermal cells after transferring into recipient embryos was examined morphologically. 2. Donor blastodermal cells were distributed near the site of injection in the epiblast and in the subgerminal cavity and yolk. Some filled the hole made by the micropipette and were distributed outside the epiblast. Many were buried in yolk. In some cases, more donor blastodermal cells were located in the yolk than in the subgerminal cavity and some were located 800 microm below the under-surface of the epiblast. 3. It is recommended that injection should be as shallow as possible to increase the proportion of chimeras produced, and that some means is needed to prevent blastodermal cells from escaping from the hole produced by injection.

Animals↗
PubMed1997

Isolation and characterization of matrix associated region DNA fragments in rice (Oryza sativa L.).

To investigate the interactions between chromosomal DNA and nuclear matrices in higher plants, matrix associated regions (MARs) of rice (Oryza sativa L.) DNAs were cloned. First, we prepared nuclear matrices from isolated nuclei by digesting them with EcoRI and then extracting with 2 M NaCl. About 6% of the total DNA remained in the nuclear matrices after this digestion and extraction. The residual DNA fragments in the nuclear matrices were cloned. Some of the cloned DNA fragments showed binding to certain nuclear proteins. One of the MAR fragments contained sequences related to known consensus motifs and a hairpin loop structure. A method is presented for isolation of matrix associated region (MAR) DNAs from plant cells.

Base Sequence↗
PubMed1997

Primary non-Hodgkin's lymphoma of the maxillary sinus.

Primary non-Hodgkin's lymphoma of the maxillary sinus is a rare lesion. We studied nine patients with malignant lymphoma involving the maxillary sinus, treated between 1980 and 1994 in the Kyushu University Hospital. All lymphomas had a diffuse pattern; five were the large-cell type, two the mixed type, and one the small lymphatic and small cleaved type. Immunohistologically, all tumors were B-cell type. Using the Ann Arbor staging system, six patients were classified as stage I, two stage II, and one stage IV. Two patients received only radiotherapy because of advanced age; the remaining seven received a combination of radiotherapy and chemotherapy (CHOP or VEPA). The tumor doses ranged from 30 to 51 Gy (mean, 46.7). The mean follow-up was 51 months. Only one patient (stage IV) died of disease, and eight stage I-II patients were rendered disease-free. The 5-year survival rate was 80%, suggesting that primary lymphoma of the maxillary sinus has a relatively good prognosis.

Adult↗