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Biomedical subjects

S Koga

Publications and source records attributed to S Koga.

At least 109 records · Page 6Linked to original sources
PubMed1996

[Evaluation of the clinical usefulness of super dynamic 99mTc-HM-PAO SPECT in ischemic cerebrovascular disease--detection of hypo- and hyperperfusion area].

The purpose of this study is to assess the clinical usefulness of super dynamic SPECT of 99mTc-HM-PAO. Six patients with unilateral occlusion of middle cerebral artery (MCA) or internal carotid artery (ICA) in the chronic phase, and 5 patients with subacute cerebral infarction were studied. We used a ring-type SPECT "HEADTOME." Two types of collimator were used: a high sensitivity (HS) collimator for super dynamic scan and a high resolution (HR) collimator for static scan. First, the intravenous constant infusion of 99mTc-HM-PAO (925-1480 MBq) for 1 minute was started. After 30 seconds from the beginning of the injection, we performed the 12 seconds/frame super dynamic SPECT for 2 minutes. Then, the static SPECT for 10 minutes was done. For semiquantitative analyses, differential percentage of regional activity between affected and non-affected hemispheres was calculated in the 6th frame image of super dynamic SPECT and static SPECT image. In all 6 patients with unilateral occlusion of MCA and ICA, super dynamic SPECT images showed the better contrast of low perfusion areas in comparison with the static SPECT images. In 5 patients with subacute cerebral infarction who showed focal hyperactivities on static SPECT, focal hyperactivities (hyperperfusion or hyperemia) were displayed in 3 cases, whereas, focal hypo- or isoactivities (hypo- or isoperfusion) were shown in 2 cases on super dynamic SPECT. However, all patients with subacute cerebral infarction showed hyperfixation on static SPECT as compared with super dynamic SPECT. Although the image quality on super dynamic SPECT is not as high as that on static SPECT, cerebral hemodynamics would be detected with less backdiffusion of 99mTc-HM-PAO from the brain to blood, and with less accumulation of hydrophilic components in subacute infarct region. In conclusion, super dynamic SPECT in early distribution of 99mTc-HM-PAO using dedicated SPECT device might be helpful to detect cerebral perfusion close to true cerebral blood flow distribution.

Aged↗
PubMed1995

Hypoxia-mediated induction of acidic/basic fibroblast growth factor and platelet-derived growth factor in mononuclear phagocytes stimulates growth of hypoxic endothelial cells.

Wound repair and tumor vascularization depend upon blood vessel growth into hypoxic tissue. Although hypoxia slows endothelial cell (EC) proliferation and suppresses EC basic fibroblast growth factor (bFGF) expression, we report that macrophages (MPs) exposed to PO2 approximately 12-14 torr (1 torr = 133.3 Pa) synthesize and release in a time-dependent manner platelet-derived growth factor (PDGF) and acidic/basic FGFs (a/bFGFs), which stimulate the growth of hypoxic ECs. Chromatography of hypoxic MP-conditioned medium on immobilized heparin with an ascending NaCl gradient resolved three peaks of mitogenic activity: activity of the first peak was neutralized by antibody to PDGF; activity of the second peak was neutralized by antibody to aFGF; and activity of the third peak was neutralized by antibody to bFGF. Metabolically labeled lysates and supernatants from MPs exposed to hypoxia showed increased synthesis and release of immunoprecipitable PDGF and a/bFGF in the absence of changes in cell viability. Possible involvement of a heme-containing oxygen sensor in MP elaboration of growth factors was suggested by the induction of bFGF and PDGF by normoxic MPs exposed to nickel or cobalt, although metabolic inhibitors such as sodium azide were without effect. These results suggest a paracrine model in which hypoxia stimulates MP release of PDGF and a/bFGF, inducing EC proliferation and potentially promoting angiogenesis in hypoxic environments.

Animals↗
PubMed1995

Integrated life-sized solid model of bone and soft tissue: application for cleft lip and palate infants.

The recent development of three-dimensional computed tomography (3D-CT) and laser stereolithography has allowed the creation of life-sized skeletal models. The development of helical CT has enabled us to apply this method to very young children. However, skeletal models alone do not reveal the spatial relationship between soft tissue and bone in complicated craniofacial deformities. We have therefore developed a model that shows both soft and bony tissue by first using CT values that result in a model in which soft tissue is solid and bone is replaced by empty space. The space is then filled with plaster to represent the skeleton. This model also can provide baseline data for evaluating facial growth after surgical repair of clefts. Two infants with cleft lip and palate are presented to illustrate this method of creating an integrated solid model and its applications.

Bone and Bones↗
PubMed1995

TNF modulates endothelial properties by decreasing cAMP.

Tumor necrosis factor-alpha (TNF-alpha), a monokine that contributes to vascular dysfunction accompanying the host response to gram-negative sepsis, has been shown to increase vascular permeability in vivo and to diminish the barrier function of cultured endothelial cell (EC) monolayers. The studies reported here indicate that a mechanism through which TNF alters EC barrier function involves a reduction in intracellular adenosine 3',5'-cyclic monophosphate (cAMP) content, due in part to increased cyclic nucleotide phosphodiesterase (CNPDE) activities. TNF increased the diffusional transit of [3H]sorbitol, [3H]inulin, and 125I-labeled albumin across confluent bovine aortic EC monolayers. This effect of TNF was both time and dose dependent and occurred in parallel with a fall in EC cAMP. cAMP analogues, such as dibutyryl cAMP (DBcAMP), prevented TNF-induced perturbation of EC barrier function. TNF also mediated another important alteration in the EC phenotype, in that both mRNA and activity of the anticoagulant cofactor thrombomodulin were reduced after exposure of EC to TNF and were normalized by the addition of DBcAMP. EC monolayers exposed to TNF-alpha showed increased cAMP levels when exposed to 3-isobutyl-1-methylxanthine, a nonspecific CNPDE inhibitor. Ion exchange chromatography of cytosol derived from TNF-treated EC consistently showed an approximately 245% increase in phosphodiesterase (PDE) IV (high-affinity, cAMP-specific PDE) activity as identified by rolipram inhibition. PDE II activity was increased by 150% after TNF-alpha treatment of early passage EC, which was identified by cGMP-activated hydrolysis of cAMP. Western and Northern analyses, as well as activity studies, revealed that TNF treatment did not change the amount of PDE IV protein or mRNA but rather increased the specific activity of the isozyme, suggesting that a posttranslational modification had occurred. These data indicate that activation of EC CNPDE activity and decreased intracellular cAMP may represent a mechanism by which TNF increases EC permeability and promotes a procoagulant EC phenotype.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1995

[Clinical usefulness of MRI in acute phase of spinal multiple sclerosis--influence of high-dose steroid therapy in acute phase].

Magnetic resonance imaging (MRI) is useful for detecting spinal cord lesions in multiple sclerosis (MS). In this study, we have examined MRI for 14 patients (26 cases) with clinically definite MS and investigated the correlations between neurological and MRI findings before and after high-dose corticosteroid therapy (pulse therapy). High signal intensity areas on T2-weighted images (T2WI) were found in 25 of 26 cases. In 22 cases spinal level of clinically suspected lesions were involved in these high intensity areas. T1-weighted images (T1WI) after intravenous gadolinium with diethylenetriamine pentaacetic acid (Gd-DTPA) were also obtained and in 12 of 17 cases before pulse therapy, the symptoms and enhancement of lesions correlated well. The symptoms regressed in all cases after pulse therapy, and high-intensity areas in T2WI became less distinct. Gd-DTPA enhanced areas disappeared in 6 cases and became smaller in 3 of 12 cases. Additional pulse therapy in 3 cases effectively diminished the enhanced areas in these cases. In one patient who had repeated pulse therapy, MRI showed no enhancement. In two other patients who continued on decreased steroid dose had relapses, pulse therapy was therefore started again, providing a good recovery both clinically and radiologically. The changes of MRI findings and clinical course suggest that the pathological changes in spinal MS may be caused not only by demyelination but also by parenchymal edema. Clinical and MRI concordance was significantly better with Gd-DTPA enhanced T1WI than the high-intensity areas in T2WI. Contrast enhancement gives more information about disease activity and the reaction to therapy.

Acute Disease↗
PubMed1995

[Quantitative analysis of individual renal function using 99mTc-DMSA scintigram--comparison with 131I-OIH renogram].

99mTc-2,3-di-mercapto-succinic acid (DMSA) is able to be used for the quantitative analysis of individual renal function by calculating the uptake ratio. The purpose of this study is to assess the clinical feasibility of DMSA uptake ratio as compared with 131I-ortho-iodo-hippuran (OIH) renogram pattern. Two hundred eleven cases (191 patients, 1 to 87 years old) with renal disorders and 4 normal volunteers (27.8 +/- 2.4 years old) were studied. Just prior to the DMSA study in the same day, OIH renogram was carried out. They were divided into 6 types by OIH renogram patterns. In 24 cases of normal renogram pattern and normal blood data who were defined as the normal group and 4 normal volunteers, DMSA uptake ratio showed negative correlation with increasing age (r = 0.61, p < 0.05). Patients of the severe impaired functioning and the non functioning patterns showed significantly decreased DMSA uptake ratios as compared with the normal pattern. There was also a significant difference in DMSA uptake between impaired functioning patterns. Compensative hemi-hypertrophy kidneys showed significantly higher DMSA uptake ratios than those of atrophic kidneys. The possibility of the quantitative analysis of the functional compensation was presumed. In conclusion, quantitative analysis of individual renal function using DMSA uptake ratio is considered to be useful to evaluate the renal functional reserve.

Adolescent↗
PubMed1995

[Clinical usefulness of helical-scanning CT for the evaluation of arteriosclerotic carotid lesions].

We examined arteriosclerotic carotid lesions in 76 patients using helical scanning CT (HES-CT), and evaluated the clinical usefulness of this method. A high speed slip-ring X-ray CT system was used. Scanning of the neck was performed for a 30 second period following intravenous bolus injection of non-ionic contrast medium, while couch top movement was 2.0 mm/sec. Multiplannar reconstruction images (MPR-image) and 3-dimensional surface images (3D-image) were reconstructed from the continuous raw data. MPR-images offered axial, coronal and sagittal images in which the lesion could be seen from any direction, and 3D-images that could be freely rotated were obtained by using a track ball and monitor. Eighteen cases were also evaluated by conventional angiography. Excellent HES-CT images were obtained in 73 cases, showing occlusion in 13, stenosis in 34, plaques without calcification in 15 and plaques with calcification in 74 vessels. A good correlation was obtained between HES-CT and angiogram in most cases, and in 6 cases, HES-CT was superior in the detection of stenosis, because it enabled us to observe the lesion from various directions. These results suggested that HES-CT was a minimally invasive, useful diagnostic method for the evaluation of arteriosclerotic carotid disease.

Arteriosclerosis↗
PubMed1994

[Development of real-time CT fluoroscopy].

A new CT system that permits real-time monitoring of CT images was developed. Phantom and volunteer studies revealed that the images were displayed at a rate of six per second with a delay time of 0.83 second with clinically sufficient resolution (256 x 256) using the newly developed fast image processor and partial-reconstruction algorithm. The clinical trial of stereotactic aspiration of intracerebral hematoma was successful. The initial trial with CT fluoroscopy revealed potential usefulness of the system in biopsy and other CT-guided interventions.

Biopsy, Needle↗
PubMed1994

[Detectability of cerebral aneurysms and surrounding vessels by three-dimensional evaluation using helical scanning CT (HES-CT)].

Helical scanning CT (HES-CT) is a new technique to enable high-speed volumetric data acquisition. We have applied HES-CT to the diagnosis of cerebral vascular diseases. In our experience, the relationship between the scanning parameters of HES-CT and image quality was complex and reciprocal, so that optimization of the parameters according to the clinical demands was essential. We compared HES-CT with conventional cerebral angiography to determine the detectability of the aneurysm and surrounding vessels, and sought the optimal parameters to delineate small vessels. All aneurysms were detected in multiplanar reconstruction (MPR) images. The smallest one was 3 x 4 mm. MPR images were found to have some advantages over conventional cerebral angiography in delineation of intracranial aneurysms: 1) scanning was over in a short time (30s), 2) the relationship between the aneurysm and surrounding vessels was easily recognized, 3) the diameter of the neck could be measured, because the neck of the aneurysm and parent artery could be imaged on the same plane without overlapping another vessel, 4) calcified lesions on the aneurysmal wall were detected, and 5) HES-CT was done safety without arterial puncture. However, the detectability of unknown aneurysm was less than the detectability of known aneurysm in MPR images. The 180 degrees interpolation algorithm and 1 mm slice were effective in detecting small vessels. However, vessels with a diameter less than 1 mm could not be detected by HES-CT. HES-CT was considered to be useful as a supplementary examination to conventional angiography for the diagnosis of intracranial aneurysms.

Adolescent↗
PubMed1994

Evaluation of regional cerebral blood flow changes on perifocal brain tissue SPECT before and after removal of arteriovenous malformations.

In fifteen cases of arteriovenous malformation (AVM), serial examinations of regional cerebral blood flow (rCBF) using single photon emission computed tomography (SPECT) and N-isopropyl-(123I)p-iodoamphetamine were performed. On SPECT images, the nidus was visualized as a focal rCBF defect in all cases preoperatively and seven of these cases had abnormal decreased perfusion areas in the tissues adjacent to the nidus. In five cases, the postoperative SPECT images on the day after surgery revealed an abnormal increased perfusion area adjacent to the nidus and in one case the increased perfusion was accompanied by a massive intracerebral haemorrhage detected by brain computed tomography (CT). In seven cases, postoperative SPECT images showed widespread abnormal decreased perfusion areas in the surrounding tissues and brain CT revealed either intracerebral haemorrhage or significant cerebral oedema. In the other three cases, no remarkable rCBF changes were found in comparison with the pre-operative study. There was a tendency for the preoperative abnormal decreased perfusion area adjacent to the nidus to correlate with the postoperative hyperperfusion and for the postoperative abnormal decreased perfusion area to reflect brain damage.

Adolescent↗
PubMed1994

Cardiac preservation is enhanced in a heterotopic rat transplant model by supplementing the nitric oxide pathway.

Nitric oxide (NO) is a novel biologic messenger with diverse effects but its role in organ transplantation remains poorly understood. Using a porphyrinic microsensor, the first direct measurements of coronary vascular and endocardial NO production were made. NO was measured directly in the effluent of preserved, heterotopically transplanted rat hearts stimulated with L-arginine and bradykinin; NO concentrations fell from 2.1 +/- 0.4 microM for freshly explanted hearts to 0.7 +/- 0.2 and 0.2 +/- 0.08 microM for hearts preserved for 19 and 38 h, respectively. NO levels were increased by SOD, suggesting a role for superoxide-mediated destruction of NO. Consistent with these data, addition of the NO donor nitroglycerin (NTG) to a balanced salt preservation solution enhanced graft survival in a time- and dose-dependent manner, with 92% of hearts supplemented with NTG surviving 12 h of preservation versus only 17% in its absence. NTG similarly enhanced preservation of hearts stored in University of Wisconsin solution, the clinical standard for preservation. Other stimulators of the NO pathway, including nitroprusside, L-arginine, or 8-bromoguanosine 3',5' monophosphate, also enhanced graft survival, whereas the competitive NO synthase antagonist NG-monomethyl-L-arginine was associated with poor preservation. Likely mechanisms whereby supplementation of the NO pathway enhanced preservation included increased blood flow to the reperfused graft and decreased graft leukostasis. NO was also measured in endothelial cells subjected to hypoxia/reoxygenation and detected based on its ability to inhibit thrombin-mediated platelet aggregation and serotonin release. NO became undetectable in endothelial cells exposed to hypoxia followed by reoxygenation and was restored to normoxic levels on addition of SOD. These studies suggest that the NO pathway fails during preservation/transplantation because of formation of oxygen free radicals during reperfusion, which quench available NO. Augmentation of NO/cGMP-dependent mechanisms enhances vascular function after ischemia and reperfusion and provides a new strategy for transplantation of vascular organs.

Amino Acid Oxidoreductases↗
PubMed1994

[Continuous noninvasive measurements of cardiac output during exercise by impedance cardiography--application to evaluation of cardiac output kinetics].

The purpose of the present study was to compare the impedance derivate waveforms using spot and band electrode array and to assess applicability of automated signal processing system for cardiac output kinetics. Five healthy male subjects were tested. Cardiac output (Q) were measured using spot electrode array. Each subject performed rest-exercise transitions in leg and arm exercise on an electrically braked ergometer. The intensities of leg exercise were 25, 50, and 100 W for 5 min and those of arm exercise were 25 and 50 W. Comparisons between spot and band electrodes were made for the absolute magnitude of Q and stroke volume (SV), as well as for impedance derivative waveforms. The waveforms for spot electrodes showed less fluctuation by breathing and movement artifacts than for band electrodes. Q for spot electrodes were larger than those for band electrodes. There was a significant correlationship between oxygen uptake (Vo2) and Q. There was a significant correlationship between Q using spot electrode and Q measured by CO2 rebreathing method. Nonlinear correlation coefficient to exponential curve of Q kinetics for leg exercise was more than 0.7 and for arm exercise more than 0.4 in spite of large movement of upper body. It is suggested that the present system using spot electrodes is superior in signal processing to those for band electrodes and able to evaluate Q kinetics without multiple repetition of exercise tests.

Adult↗
PubMed1994

Alcaptonuria: a case complicated with valvular heart disease and immunodeficiency.

A 75-year-old man was diagnosed with alcaptonuria by direct identification of homogentisic acid in the urine using gas chromatography-mass spectrometry. Complications included valvular heart disease with marked calcification detected by two-dimensional color-Doppler echocardiography and recurrent bacterial infection. Immunological analyses revealed a reduced number of T cells with compensatory expansion of CD56+, CD57+ natural killer (NK) cell population and impaired functions of cellular immunity such as phytohemagglutinin response, antibody-dependent cellular cytotoxicity, NK activity and interleukin-2 production. Humoral immunity and neutrophil functions were considered to be normal. This is the first reported case of alcaptonuria to our knowledge in which immunological abnormality was documented.

Aged↗
PubMed1994

[Clinical examination and therapies of hydronephrosis after radical hysterectomy].

We investigated postoperative hydronephrosis in 50 patients (100 ureter) undergoing radical hysterectomy for uterine cervical cancer from Jan. 1989 to Dec. 1991 at Department of Obstetrics and Gynecology in Nagasaki University Hospital. The incidence of hydronephrosis was 68.1% of patients, and hydronephrosis was seen significantly more frequently and was of a higher grade on the right kidney than the left. After one year, hydronephrosis disappeared in 59.1% of patients (65.1% of right kidney, 88.2% of left kidney), and only 2 of 93 kidney have worsened. In cases without hydronephrosis, hydronephrosis developed in only 3 of 31 kidney after one year due to local recurrence or nodule metastasis of the original disease. We compared therapeutic effects of 3 methods (ureteral stent, PNS, no treatment). But there was no significant difference between these methods, we could not determine which was the best treatment. And we observed that indwelling ureteral stent might interrupt spontaneous healing of ureter. Radiotherapy didn't significant influence hydronephrosis after radical hysterectomy; Therefore, we suggest that, in patients with hydronephrosis without other severe urological complications after radical hysterectomy, clinical course should be observed for at least one year, first and them some treatments should be applied if cases worsen gradually than before.

Adult↗