Biomedical subjects

A Kubo

Publications and source records attributed to A Kubo.

At least 181 records · Page 10Linked to original sources

PubMed1995

Expression of Arabidopsis cytosolic ascorbate peroxidase gene in response to ozone or sulfur dioxide.

The effects of ozone or sulfur dioxide on antioxidant enzymes were investigated in Arabidopsis thaliana. Plants were fumigated with 0.1-0.15 ppm ozone or sulfur dioxide up to about 1 week in an environment-controlled chamber. Both pollutants increased the activities of ascorbate peroxidase and guaiacol peroxidase in leaves, but had little effect on the activities of superoxide dismutase, catalase, monodehydroascorbate reductase, dehydroascorbate reductase or glutathione reductase. Ozone was more effective than sulfur dioxide in increasing the activities of the peroxidases. Ascorbate peroxidase activity increased 1.8-fold without a lag period during fumigation with 0.1 ppm ozone, while guaiacol peroxidase activity increased 4.4-fold with a 1-day lag. Expression of the APX1 gene encoding cytosolic ascorbate peroxidase was further investigated. Its protein levels in leaves exposed to 0.1 ppm ozone for 4 or 8 days were 1.5-fold higher than in controls. Both ozone and sulfur dioxide elevated APX1 mRNA levels in leaves at 4 and 7 days, whereas at 1 day only ozone was effective. The induction of APX1 mRNA levels by ozone (3.4- to 4.1-fold) was more prominent than that by sulfur dioxide (1.6- to 2.6-fold). The APX1 mRNA level increased by day and decreased by night. Exposure of plants to 0.1 ppm ozone enhanced the APX1 mRNA level within 3 h, which showed a diurnal rhythm similar to that of the control. These results demonstrate that near-ambient concentrations of ozone as well as similar concentrations of sulfur dioxide can induce APX1 gene expression in A. thaliana.

Air Pollutants↗

PubMed1995

Structural functions of antimicrobial long-chain alcohols and phenols.

Antimicrobial activity of a series of long-chain alcohols and common naturally occurring alcohols were tested against 15 selected microorganisms in order to gain new insights into their structural functions. The maximum activity seems to depend on the hydrophobic chain length from the hydrophilic hydroxyl group, and also the microorganisms being tested. The results obtained with the alcohols exhibit a generally applicable rule to many other compounds.

Alcohols↗

PubMed1995

Characteristics and expression of transforming growth factor-beta receptor subtypes on vascular smooth muscle cells from spontaneously hypertensive rats.

OBJECTIVE: To investigate the characteristics and expression of transforming growth factor (TGF)-beta receptor subtypes on vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. METHODS: The effects of TGF-beta 1 on DNA synthesis were evaluated by [3H]-thymidine incorporation into quiescent VSMC plated at high (5 x 10(4) cells/cm2) or low (5 x 10(3) cells/cm2) cell density. Specific binding of TGF-beta to VSMC was assessed by incubation of the cells with [125I]-TGF-beta 1. Affinity labelling of receptor subtypes was achieved by exposure of the cells to [125I]-TGF-beta 1 and cross-linking with disuccimidyl suberate. RESULTS: VSMC from SHR displayed a biphasic DNA synthesis response to TGF-beta 1 at high cell density, with DNA synthesis stimulated by low concentrations of TGF-beta 1 but not by high concentrations, whereas at low cell density there was a small increase in DNA synthesis in response to TGF-beta 1. TGF-beta 1 inhibited DNA synthesis in VSMC from WKY rats at both high and low cell densities. Binding assays revealed that VSMC from SHR had a larger number of TGF-beta receptors and a higher affinity for TGF-beta at high and at low cell densities. The affinity labelling with [125I]-TGF-beta 1 revealed the presence of receptor subtypes with relative molecular masses of 280-300, 85, 70, 60 and 50 x 10(3) on vascular smooth muscle cells from both rat strains at high cell density. The abundance of the 85 x 10(3) molecular mass receptor subtype was greater in VSMC from SHR. The 85 x 10(3) molecular mass receptor subtype was not detected on VSMC from either strain at low cell density. CONCLUSION: The present results suggest a different expression of TGF-beta receptor subtypes on VSMC from SHR and WKY rats. These differences may account for the exaggerated proliferative response of VSMC from SHR to TGF-beta.

Animals↗

PubMed1995

Distinct expression of transforming growth factor-beta receptor subtypes on vascular smooth muscle cells from spontaneously hypertensive rats and Wistar-Kyoto rats.

1. We investigated the characteristics and expression of transforming growth factor-beta (TGFbeta) receptor subtypes on vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. 2. TGFbeta binding assays revealed that VSMC from SHR showed higher number and affinity of TGFbeta receptors than cells from WKY rats. 3. The affinity labelling with [125I]-TGFbeta1 revealed the presence of TGFbeta receptor subtypes with molecular sizes of 280, 85, 70 and 60kDa on VSMC from both strains at high cell density. The abundance of the 85kDa receptor subtype was greater in VSMC from SHR than cells from WKY rats. The 85kDa receptor subtype was not detected on VSMC from both strains at low cell density. 4. These results suggest distinct expression of TGFbeta receptor subtypes on VSMC from SHR and WKY rats, which may account for the exaggerated proliferative response of VSMC from SHR to TGFbeta.

Affinity Labels↗

PubMed1995

Effect of external negative pressure on pulmonary 99mTc-DTPA clearance in humans.

We studied the mechanisms by which pulmonary solute clearance is affected by lung inflation. We examined the pulmonary clearance of inhaled technetium-99m diethylenetriaminepentaacetic acid (99mTc-DTPA) together with changes in lung volumes in healthy men after applying graded levels of continuous external negative pressure (CNP) and positive end-expiratory pressure (PEEP). The 99mTc-DTPA clearance increased from the baseline during -15 cm H2O CNP (p < 0.005) and during -20 cm H2O CNP (p < 0.001). The 99mTc-DTPA clearance increased during +15 cm H2O PEEP (p < 0.001). However, the changes during both -10 cm H2O CNP and +10 cm H2O PEEP did not differ from the baseline, indicating a threshold effect. On the other hand, changes in FRC during CNP were proportional to the applied pressures and were similar to those during PEEP with corresponding pressures. These results suggest that pulmonary vascular recruitment induced by CNP does not affect pulmonary 99mTc-DTPA clearance. This threshold effect suggests that the increased clearance is due to changes in membrane permeability rather than in the area of the alveolar-capillary interface or the lining layer thickness. We concluded that the effect of lung inflation on solute clearance may be mediated by the changes in membrane permeability.

Adult↗

PubMed1995

Synthesis of saframycins. X. Transformation of (-)-saframycin A to (-)-saframycin Mx type compound with the structure proposed for saframycin E.

Treatment of (-)-saframycin A (1a) with selenium oxide in acetic acid afforded (-)-saframycin G (1g), and a catalytic reduction and regioselective oxidation sequence afforded the saframycin Mx type compound (3). We applied this methodology to the transformation of (+/-)-5-hydroxysaframycin B (11) to the hydroquinone (1e). Acetylation of 1e with acetic anhydride in pyridine gave the triacetate (13), which is identical with the triacetyl derivative of natural saframycin E.

Anti-Bacterial Agents↗

PubMed1995

[Palliative radiotherapy for symptomatic osseous metastases].

Bone metastases are one of the most common and serious conditions requiring radiotherapy, but there is still a considerable lack of agreement on optimal radiation schedule. We analyzed patients with symptomatic osseous metastases from lung (72 patients) and breast (63 patients) carcinoma treated by palliative radiotherapy between 1983 and 1992. In this series, the incidences of symptomatic bone metastases appearing within 2 years after the first diagnosis of the primary lesion were 96% and 36% for lung and breast carcinomas, respectively. Thirty percent of bone metastases from breast carcinoma were diagnosed more than 5 years after the first diagnosis. Thus careful follow-up must be carried out for a prolonged period. Pain relief was achieved at almost the same rate for bone metastases from lung and breast carcinomas (81% and 85%, respectively), an the rapid onset of pain relief (15 Gy or less) was obtained in about half the patients for both diseases. The rapid onset of pain relief and the lack of association between the onset of pain relief and primary tumor argued against the conventional theory that tumor shrinkage is a component of the initial response. In contrast to the fact that almost all lung carcinoma patients had very poor prognoses, one third of the breast carcinoma patients were alive more than 2 years after palliative radiotherapy. Thus, the late effects of radiation, such as radiation myelopathy, must be always considered especially in breast carcinoma patients even when it is 'just' palliative radiotherapy for bone metastases.

Adult↗

PubMed1995

[Phase II clinical trial of the radioactive strontium (89Sr) chloride agent, SMS. 2P for pain palliation in patients with prostate cancer with bone metastases].

The phase II clinical trial of a strontium (89Sr) chloride agent (SMS. 2P) was performed in 9 patients with painful bone metastases secondary to prostate cancer. After an intravenous administration, 89Sr circulated in the plasma and was rapidly cleared. Urinary excretion varied widely among the patients. No serious acute side effects were observed. A mild transient increase in pain was reported by 4 patients 2-4 days after administration, two of whom complained of mild nausea or vomiting. All symptoms improved and never became a clinical problem. There were some abnormal hematological parameters. In particular, a decrease in the platelet level seemed to be a marrow suppression due to 89Sr irradiation. It is difficult to discriminate between the effects of 89Sr and the progress of the disease using tumor markers. The pain level improved within 2 weeks after administration and the effect continued for at least 8 weeks, which improved the quality of life for these patients.

Aged↗

PubMed1995

[123I-beta-methyl-iodophenyl-pentadecanoic acid myocardial scintigraphy in diabetic patients without overt ischemic heart disease].

Fatty acid metabolism in the myocardium is affected by metabolic disorders such as diabetes mellitus. We evaluated 123I-beta-methyl-iodophenyl-pentadecanoic acid (BMIPP) myocardial scintigraphy in 15 diabetes mellitus patients without overt coronary heart disease. Patients with overt coronary heart disease were excluded by careful history taking, resting electrocardiography, treadmill exercise testing, echocardiography and resting 201Tl scintigraphy. Patients with remarkably impaired left ventricular (LV) systolic function (%FS < 30%) were also excluded. BMIPP uptake scores as the ratio of heart/mediastinum (H/M) and liver/mediastinum (L/M) at 20 minutes after injection were analyzed and compared with clinical profile, serum parameters, and LV parameters obtained from echocardiography. Five of the 15 patients showed abnormal BMIPP images; two patients showed a decreased uptake in the inferior segments, while three showed a diffuse decrease in BMIPP uptake. Body mass index (BMI), fasting blood sugar (FBS), HbAlc, IRI, and LV end-diastolic diameter (LVEDD) were higher in these five patients with abnormal BMIPP findings (abnormal BMIPP group vs normal BMIPP group, BMI: 29 vs 23 kg/m2, p < 0.05; FBS: 178 vs 114 mg/dl, p < 0.01; HbAlc: 7.6 vs 6.2%, p < 0.01; IRI: 18.5 vs 9.5 microU/ml, p < 0.01; LVEDD: 52 vs 44 mm, p < 0.05). 123I-metaiodobenzyl-guanidine (MIBG) scintigraphy in the five patients with abnormal BMIPP uptake showed more severe defects than in the 10 patients with normal BMIPP imaging. BMIPP scintigraphy demonstrated a significant correlation between H/M and L/M by BMIPP (r = 0.74, p < 0.01). Furthermore, correlation between H/M by BMIPP scintigraphy and clinical parameters (BMI, systolic blood pressure, FBS, HbAlc, IRI) were found, suggesting that diabetes mellitus patients without over coronary heart disease show abnormal BMIPP imaging when their general glucose utility and 123I-MIBG uptake are severely impaired (progression of insulin resistance and sympathetic nerve involvement). BMIPP scintigraphy may be useful in investigating the pathogenesis and subclinical abnormality of diabetic heart.

Aged↗

PubMed1995

[Evaluation of renal function using 99mTc-MAG3 comparison with 131I-OIH by simultaneous dual energy peak acquisition method].

A newly developed 99mTc-labeled renal scintigraphic and renographic agent, 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) was studied clinically and compared with 131I-OIH in 16 patients with various renal and urinary tract disorders. The abdominal aorta and the common iliac artery were clearly visualized in the vascular phase. The renogram patterns showed the same pattern in all cases. The parameters on the renogram such as Tmax, T2/3, T1/2 were compared. The highly significant correlations of Tmax, T2/3 and T1/2 were observed between 99mTc-MAG3 and 131I-OIH with correlation coefficient of 0.982, 0.907, 0.990, respectively. In all cases, excretion of 99mTc-MAG3 was slower than that of 131I-OIH and the ratios of Tmax, T2/3 and T1/2 between 99mTc-MAG3 and 131I-OIH were 1.113 +/- 0.121, 1.277 +/- 0.247, 1.179 +/- 0.075, respectively. It is concluded that 99mTc-MAG3 is useful renal imaging agent as an alternative to 131I or 123I-OIH.

Adolescent↗

PubMed1995

[Comparison between T2*- and T2-weighted images in diagnosing rotator cuff tears].

This study was performed to determine the merits of T2*-weighted images in diagnosing rotator cuff tear, compared with T2-weighted images. T2-and T2*-weighted images were obtained in 10 asymptomatic volunteers and 94 patients with symptoms referable to the rotator cuff. The increased signal with full thickness of the rotator cuff was not shown on either T2- or T2*-weighted images in the volunteers. These findings on T2-weighted images and on T2*-weighted images were observed in 33 and 58 of 94 patients with symptoms, respectively. Every patient who showed these abnormal findings on T2-weighted images had the abnormal findings on T2*-weighted images. These findings on T2*-weighted images were wider than those on T2-weighted images in 20 of 33 patients. Surgical findings were available in 21 of 94 patients. Rotator cuff tears were surgically confirmed in 20 patients whose MR images showed increased signal lesions on both T2- and T2*-weighted images. On the other hand, one patient who did not have rotator cuff tear showed increased signal lesion with full thickness on T2*-weighted images, but not on T2-weighted images. We think increased signal lesions on T2-weighted images may strongly suggest rotator cuff tear, whereas those on T2*-weighted images are not specific.

Adolescent↗

PubMed1995

[Dose-volume histogram comparison among techniques of linac stereotactic radiosurgery].

The aim of this study was to analyze the three-dimensional dose distributions produced by various techniques used in current radiosurgery treatments by means of dose-volume histograms (DVH). Off-center ratio and tissue-peak ratio from 6-MV X-rays through additional cylindrical collimators were measured in advance for dose calculation. The use of the diamond detector and beam profile film dosimetry in small fields were certified. The impact of arc number, arc geometry, and field size on the dose distribution in a spherical phantom was evaluated through the use of DVH. These were calculated for a) four arc irradiations with collimator sizes of 5, 10, 20 and 30 mm in diameter, and b) for single-plane rotation, four or eleven multiple non-coplanar convergent arcs, dynamic rotation and precessional converging radio-therapy (PCR) with a field size of 20 mm. PCR is performed in the sitting position with the patient seated on a special treatment chair, which is rotating continuously while the gantry moves from the top to the center of the chair rotation. Most of the differences between techniques were found in a range of less than 40% of the maximum dose. Multiple non-coplanar convergent arcs with four or eleven arcs and PCR performed similar result in DVH, while single-plane rotation revealed almost unacceptably shallow dose falloffs. The DVH of dynamic rotation was between that of single-plane rotation and the other three methods.

Humans↗

PubMed1995

[Quantitative brain SPECT imaging with scatter and attenuation compensation: comparison of sequential and simultaneous acquisition of transmission and emission data].

Scatter and attenuation correction for brain SPECT of a phantom and a normal volunteer was performed using the Triple Energy Window method combined with a transmission scan. 99mTc-ECD and 99mTc solution were used as an emission tracer and a transmission source, respectively. We employed a triple-headed SPECT gammacamera system equipped with fan-beam collimators for acquisition with line transmission sources placed at the focal lines of the fanbeam collimators. Two mode, sequential mode and simultaneous mode, of data acquisition protocols were examined. In the sequential mode, a transmission scan was carried out using three external sources for the brain phantom without emission tracer. After removing all sources, an emission scan was performed on the brain phantom containing the tracer. In the simultaneous mode, the injection was followed by a simultaneous transmission-emission scan using one transmission source. The same study was conducted out for the normal volunteer, after confirming the effectiveness of these protocols with phantom studies. Corrected SPECT count values obtained with two protocols were almost identical. Simultaneous mode had advantages in avoiding misalignment between transmission and emission data and in shorter acquisition time than sequential mode.

Brain↗

PubMed1995

Evaluation of bi-level image converting methods for nuclear medicine image database stored in the IS&C magneto-optical disk.

1. INTRODUCTION. We have developed a report and imaging management system for nuclear medicine. The report and image data are stored in the IS&C magneto-optical disk (IS&C MOD). Nuclear medicine image data are relatively small, but they are large enough to create problems when being transported over a low-speed Hospital Information System (HIS) network. Moreover, gray scale image output devices (i.e., high-resolution displays, sonoprinters) are expensive. If high quality bi-level (black and white) images were available, images could be transferred through low-speed network with inexpensive bi-level terminals or conventional page-printers. We examined images using several bi-level image conversion techniques [1, 2] in order to determine how useful the bi-level images are and to assess their suitability for use in nuclear medicine. The images were compared with original film images by ROC analysis. The modified minimized average error method was found to be superior to other methods in bone and gallium images. Its A-values are 0.83 in gallium scan and 0.85 in bone scan. 2. MATERIALS AND METHODS. Our system consists of three digital gamma cameras, a nuclear medicine data processing unit, two UNIX stations, and two personal computers. The computers and the data processing unit are connected via Ethernet and each computer has an IS&C MOD unit. Image and report data are stored in the IS&C MOD. The computers are also connected off-line through the IS&C MOD. To evaluate image quality, bone scan images and gallium scan images (1024x512, 2048x1024 pixels and 16 bits depth) were converted to bi-level images (same pixels and one bit depth) using four methods: dither method, minimized average error method (MAE)[1], modified regional adaptation method, and constrained average method. For the dither methods, three sets of dither matrix (Fatting's, Bayer's and our original matrix) were employed. The computer images were compared with original film images by ROC analysis. 3. RESULTS. The converted bi-level images were 1/16 the size of the originals. They were transferred via Ethernet, displayed on the monochrome display, and printed using a conventional page-printer (240 dpi or 300 dpi). The A-values of the original gallium and bone images on the films were 0.89 and 0.94. Modified MAE method gave better results than other methods tested, with the gallium image using this technique reading 0.83 on the A-scale; and the bone images were 0.85. 4. DISCUSSION. Generally, nuclear medicine images require lower spatial and gray level resolution than other computer imaging techniques. We compared four bi-level image conversion methods in order to know which methods are suitable to nuclear medicine images. The ROC analysis was employed to evaluate these image qualities. The MAE methods made particular texture pattern as artifacts in the intermediate gray level area. But it can express homogeneity the neutral level. The dither method images are coarse texture. It affects detectabilities of subtle abnormal findings. 5. CONCLUSIONS. The A-z values of the modified MAE images were comparable to those of original film images. Although bone images give slightly lower values, many abnormal findings can be ascertained on bi-level images. High quality bi-level image techniques are considered to be useful for nuclear medicine image database systems.

Japan↗

PubMed1995

Development of a personal computer's viewing station for the IS&C magneto-optical disk.

We developed a display station for the medical images stored in the IS&C (Image Save and Carry) magneto-optical disk. This station consisted of the personal computer and the magneto-optical disk drive. The performance of this system was evaluated and was compared with the Unix workstations. We found that the personal computer system had an adequate ability to display medical images. It provided, moreover, for portability and practical use of medical information.

Data Display↗

PubMed1994

The roles of the N-linked carbohydrate chain of rice alpha-amylase in thermostability and enzyme kinetics.

The thermostability and kinetics of starch hydrolysis were compared between a rice alpha-amylase isozyme Amy1A and its mutant enzyme that lacks an N-linked carbohydrate chain. Elimination of the N-glycosylation site in Amy1A reduced the thermostability of the enzyme. The temperature dependence of the kinetic parameters (Vm and Km) and substrate recognition of the enzymes were also affected by elimination of the N-glycosylation site. These results suggest that the N-linked carbohydrate chain of Amy1A has important roles in the thermostability and reaction kinetics of the enzyme.

Amino Acid Sequence↗

PubMed1994

[Sonographic findings of rotator cuff tears: correlation with MR imaging].

Sonography was performed in 41 patients with symptoms referable to the rotator cuff. Sonography was performed immediately after MR imaging, so that the information obtained by MR imaging could be applied to sonographic diagnosis. Twenty patients were diagnosed from T2-weighted images as having complete tears of the rotator cuff. Sonography showed full-thickness anechoic areas in 12 of the 20 patients, heterogeneous hyperechoic areas in seven, and no abnormal findings in the other one. Thirteen patients were diagnosed as having incomplete tears with MR imaging. Sonography showed heterogeneous hyperechoic areas in 12, but no abnormal findings in one of the 13. Hyperechoic areas in the rotator cuff were shown in four of eight patients who had been diagnosed from T2-weighted images as not having tears. We consider full-thickness anechoic areas to be specific findings of complete tears, although some patients with rotator cuff tears did not show this finding.

Adult↗

PubMed1994

[Parallel processing of dose calculation for external photon beam therapy].

We implemented external photon beam dose calculation programs into a parallel processor system consisting of Transputers, 32-bit processors especially suitable for multi-processor configuration. Two network conformations, binary-tree and pipeline, were evaluated for rectangular and irregular field dose calculation algorithms. Although computation speed increased in proportion to the number of CPU, substantial overhead caused by inter-processor communication occurred when a smaller computation load was delivered to each processor. On the other hand, for irregular field calculation, which requires more computation capability for each calculation point, the communication overhead was still less even when more than 50 processors were involved. Real-time responses could be expected for more complex algorithms by increasing the number of processors.

Mathematical Computing↗