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Biomedical subjects

H Ishizaka

Publications and source records attributed to H Ishizaka.

At least 19 recordsLinked to original sources
PubMed2001

Pupillary abnormality on admission and brain bulging during surgery as unfavourable predictors in patients treated with hypothermia: a retrospective review of 81 patients with severe head injury.

BACKGROUND: To determine factors predicting outcome of patients with severe head injury, the authors retrospectively analyzed 81 patients, 3 to 70 years of age, who were treated by hypothermia. METHOD: The initial Glasgow Coma Scale scores of the 81 patients ranged from 3 to 8. Outcome in each case was determined at six months after injury and was retrospectively analyzed with respect to patient characteristics, initial clinical status, laboratory data, computed tomographic findings, data from monitoring, intra-operative findings, and treatment methods. The significance of clinical and neuroradiological factors for predicting unfavorable outcome was analyzed by univariate logistic regression. Stepwise multiple logistic regression analysis was then used to identify independent predictors of outcome. FINDINGS: Favorable outcome was observed in 27 of 81 patients treated by hypothermia. Independent factors predicting unfavorable outcome included pupillary abnormality on admission and brain bulging during surgery. INTERPRETATION: Therapeutic effectiveness of hypothermia was thus limited in patients who presented with these grave symptoms.

Adolescent↗
PubMed2001

Plasma levels of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 are increased in the coronary circulation in patients with acute coronary syndrome.

BACKGROUND: Previous studies on atherectomy specimens from patients with acute coronary syndrome (ACS) implicated the role of proteolytic enzymes. We examined whether the plasma levels of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) were increased in the coronary circulation in ACS. METHODS AND RESULTS: The plasma levels (nanograms per milliliter) of MMP-9 and TIMP-1 in the aorta (Ao) and great cardiac vein (GCV) were measured in 29 patients with ACS (20 with acute myocardial infarction [group 1] and 9 with unstable angina [group 2]), 17 with stable effort angina (group 3), and 20 control subjects (group 4). Group 1 patients had occlusion in the left anterior descending artery (LAD), and groups 2 and 3 patients had culprit lesion in the LAD. In group 1 blood samples were obtained at the time of direct coronary angioplasty done within 12 hours after the onset. The Ao level of either MMP-9 or TIMP-1 did not differ among the 4 groups. The GCV-Ao differences in MMP-9 and TIMP-1 were both significantly increased in groups 1 and 2 compared with those in group 4. Neither of them was different between groups 3 and 4. Neither the GCV-Ao difference in MMP-9 or TIMP-1 level was correlated with the maximal creatine kinase level in group 1. CONCLUSIONS: Increased plasma levels of MMP-9 and TIMP-1 were detected in the coronary circulation in ACS patients, suggesting a process of active plaque rupture in ACS.

Acute Disease↗
PubMed2000

Enhanced phospholipase C activity in the cultured skin fibroblast obtained from patients with coronary spastic angina: possible role for enhanced vasoconstrictor response.

OBJECTIVES: We measured phospholipase C (PLC) activity in the cultured skin fibroblasts obtained from patients with and without coronary spasm and examined its correlation with coronary artery vasomotility. BACKGROUND: Coronary artery vasomotility is enhanced in coronary spastic angina (CSA), but no information is available for the intracellular signaling. In spontaneously hypertensive rats, PLC activity in the skin fibroblasts has been shown to be enhanced. METHODS: Skin fibroblasts obtained from 24 patients with CSA-14 with organic coronary artery disease (CAD) and 12 control subjects--were cultured by the explant method. Activity of PLC was determined by incubating the membrane fraction with 3H-phosphatidyl inositol bisphosphate and by quantifying 3H-inositol trisphosphate. In patients with CSA and control subjects, the relations between PLC activity and coronary artery basal tone and constrictor response to intracoronary acetylcholine (ACh) were examined. RESULTS: Activity of PLC (pmol/protein [mg] per min) was 1.74+/-0.19 in patients with CSA; 0.90+/-0.12 in patients with CAD; and 0.65+/-0.07 in control subjects (p<0.001, patients with CSA vs. patients with CAD and control subjects; p = NS, patients with CAD vs. control subjects). According to the Lineweaver-Burk plot, Michaelis constant (micromol/liter) of PLC was 28+/-4 in patients with CSA; 49+/-14 in patients with CAD; and 56+/-10 in control subjects (p<0.05, patients with CSA vs. control subjects), whereas the maximal velocity was not different between the three groups. There were significant positive correlations between PLC activity and both basal tone (p = 0.0108) and response to ACh (p = 0.0053). Western blot analysis using membrane fraction demonstrated that 89% of PLC isoenzymes detected was of the delta1 isoform. CONCLUSIONS: Because the PLC activity measured was genetically defined and was positively correlated with coronary artery vasomotility, enhanced PLC activity may be involved in the pathogenesis of coronary spasm.

Angina Pectoris, Variant↗
PubMed2000

Influence of Gelation Temperature and Catalysts on the Mesoporous Structure of Resorcinol-Formaldehyde Aerogels.

Resorcinol-formaldehyde (RF) hydrogels were synthesized by sol-gel polycondensation of resorcinol with formaldehyde using a few kinds of catalysts at a gelation temperature of 238 or 332 K. RF aerogels were prepared by supercritical drying with carbon dioxide. The aerogels were characterized by nitrogen adsorption. The experimental results suggest that the gelation temperature does not greatly influence the porous properties and that sodium hydroxide and sodium hydrogencarbonate can be used as catalysts in the preparation of the aerogels. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Diffusion-weighted EPI of cystic ovarian lesions: evaluation of cystic contents using apparent diffusion coefficients.

Diffusion-weighted echoplanar imaging (EPI) was performed to evaluate the contents of cystic ovarian lesions [33 endometrial cysts, 16 ovarian cysts, 5 serous cystadenomas, 6 mucinous cystadenomas, 13 malignant cystic ovarian tumors, and 3 benign cystic lesions mimicking malignant cystic ovarian tumor (BMMs)]. Apparent diffusion coefficient (ADC) values were calculated for the cystic contents. Many lesions showed unrealistically high ADC greater than water at body temperature (0.00324 mm(2)/sec), especially in lesions more than 12 cm in diameter. The higher ADC values were attributed to the sloshing effect: intermittent compression of large ovarian lesions by abdominal breathing before the breath-hold scan. When limited to lesions with ADC less than 0. 00324 mm(2)/sec, endometrial cysts and malignant cystic ovarian tumors showed lower ADC values than ovarian cysts and serous cystadenomas (P < 0.03). When further limited to lesions less than 12 cm in axial diameter, an additional ADC difference between malignant cystic ovarian BMMs was demonstrated (P < 0.03). Diffusion-weighted EPI showed the possibility that calculated ADC values might be useful in evaluating small to medium cystic ovarian lesions. J. Magn. Reson. Imaging 2000;12:1014-1019.

Adult↗
PubMed1999

Coronary arteriolar dilation to acidosis: role of ATP-sensitive potassium channels and pertussis toxin-sensitive G proteins.

BACKGROUND: We previously demonstrated that coronary arteriolar dilation in response to acidosis is mediated by the opening of ATP-sensitive potassium (KATP) channels. However, the signal transduction involved in the KATP-channel activation during acidosis has not been elucidated. A recent study in cardiac myocytes implied that pertussis toxin (PTX)-sensitive G proteins may be involved in the signal transduction for KATP-channel activation. However, it remains unclear whether this transduction process also occurs in the vascular tissue and, in particular, whether it exerts functional dilation in response to acidosis. METHODS AND RESULTS: To examine the signaling pathway for acidosis-induced dilation, porcine coronary arterioles were isolated, cannulated, and pressurized for in vitro study. The GTPase activity in reconstituted G proteins was examined at different levels of pH. Extravascular acidosis (pH 7.3 to 7.0) produced a graded dilation of coronary arterioles. This dilation was not affected by removal of endothelium but was significantly attenuated after inhibition of KATP channels and G proteins by glibenclamide and PTX, respectively. Glibenclamide and PTX attenuated the acidosis-induced arteriolar dilation to the same extent, and combined administration of both inhibitors did not further inhibit the vasodilation. These results indicated that both inhibitors act on the same vasodilatory pathway. Furthermore, vasodilation of coronary arterioles to the KATP-channel opener pinacidil and to the endothelium-independent vasodilator sodium nitroprusside was not affected by PTX. Because PTX inhibited acidosis-induced vasodilation without inhibiting KATP-channel function, it is suggested that PTX inhibits the vasodilatory pathway upstream from KATP channels. GTPase activity in reconstituted G proteins was significantly enhanced by a reduction in pH, indicating that G proteins were directly activated by acidosis. CONCLUSIONS: On the basis of these findings, we conclude that acidosis-induced coronary arteriolar dilation is mediated by the opening of smooth muscle KATP channels through the activation of PTX-sensitive G proteins.

Acidosis↗
PubMed1999

Evaluation of cystic ovarian lesions using apparent diffusion coefficient calculated from reordered turboflash MR images.

Reordered snapshot fast low-angle shot images with, and without, diffusion-perfusion gradients were used for the evaluation of contents of cystic ovarian lesions. Sonographically detected 51 cystic ovarian lesions (13 endometrial cysts, 17 ovarian cysts, 7 serous cystadenomas, 6 mucinous cystadenomas, 8 malignant cystic ovarian tumors) were studied. T1- and T2-weighted images, reordered snapshot fast low-angle shot images with and without diffusion-perfusion gradients (b = 106 and 0 s/mm2, respectively) were obtained. Using these images, apparent diffusion coefficients (ADCs) were calculated in the cystic contents of these lesions. Endometrial cysts and malignant cystic ovarian tumors showed lower ADC values than ovarian cysts, serous cystadenomas and mucinous cystadenomas (p < 0.02). There was no distinct ADC difference among ovarian cysts, serous cystadenomas, mucinous cystadenomas (p > 0.2). In conclusion, diffusion-weighted magnetic resonance imaging is possible to be useful to evaluate cystic contents of ovarian lesions.

Adult↗
PubMed1999

Time course of free radical production after primary coronary angioplasty for acute myocardial infarction and the effect of vitamin C.

Reactive oxygen species are thought to mediate reperfusion injury after rapid revascularization for acute myocardial infarction (AMI) and 8-epi prostaglandin (PG) F2alpha, a free-radical catalyzed product of arachidonic acid, has been proposed as an indicator of oxidative stress in vivo during myocardial reperfusion. The time course of urinary 8-epi PGF2alpha excretion after primary coronary angioplasty (PTCA) for AMI was investigated, as well as the effect of prior administration of vitamin C. Urine samples, 1 before and 5 after primary PTCA (0-30, 30-60, 60-90, 90-120 and 120-150 min), were collected in 11 patients with AMI undergoing primary PTCA (Group 1), 10 patients with AMI treated with water-soluble vitamin C at an initial dose of 2.0 g followed by a constant infusion at 20mg/min prior to primary PTCA (Group 2), and 6 patients with stable effort angina undergoing elective PTCA (Group 3). 8-epi PGF2alpha was measured by enzyme immunoassay. There were no significant differences in urinary 8-epi PGF2alpha excretion at baseline among the 3 groups. In Group 1, urinary 8-epi PGF2alpha excretion (ng/mmol creatinine) significantly increased from 60+/-8 at baseline to 122+/-16 at 60-90 min (p<0.001), and declined to the baseline level at 120-150 min after primary PTCA. In Group 2, it also increased from 72+/-12 to 123+/-15 at 60-90 min (p<0.01), and the percent increase did not differ from that in Group 1. In Group 3, it remained unchanged during the study period. The free radical production is rapidly and transiently enhanced after primary PTCA for AMI, and vitamin C fails to suppress it.

Aged↗
PubMed1998

SAXS Study on Gelation Process in Preparation of Resorcinol-Formaldehyde Aerogel.

RF aerogels were prepared by sol-gel polycondensation of resorcinol with formaldehyde in a slightly basic aqueous solution and supercritical drying with carbon dioxide. The aerogels were characterized by nitrogen adsorption and density measurements. A small-angle X-ray scattering (SAXS) technique was applied to the gelation process of RF hydrogels. The structure formation of the hydrogels during the sol-gel transition was revealed by applying Guinier and power-law equations to the SAXS data. At the initial stage of the synthesis of RF hydrogels, small clusters of ca 2 nm consisting of branched polymeric species formed, showing a mass fractal dimension. Then the clusters aggregated and formed particles of ca 3-6 nm. These particles showed a surface fractal dimension. The hydrogel structure was fixed by gelation and the particles grew to ca 4-7 nm. Finally their surface became smooth by aging. The influence of the amount of resorcinol, basic catalyst, and water used in the polycondensation on the porous structures of the aerogels was explained by the structure formation model proposed. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Evaluation of cystic ovarian lesions using apparent diffusion coefficient calculated from turboFLASH MR images.

Serial turboFLASH (fast low-angle shot) images with and without diffusion-perfusion (DP) gradients were used to evaluate the contents of cystic ovarian lesions. 19 ovarian cysts seven serous cystadenomas, six mucinous cystadenomas and 13 malignant cystic ovarian tumours were studied. T1 and T2 weighted spin echo images, serial turboFLASH images with and without DP gradients (b = 295.1 and 0 s mm-2, respectively) were obtained. Using these images, the apparent diffusion coefficients (ADCs) were calculated within the cystic contents of these lesions. Approximately corrected ADC (ADC') values were also calculated in order to reduce T1 contamination from ADCs, using results of a phantom study. Ovarian cysts and serous cystadenomas showed larger ADC and ADC' values than the cystic contents of malignant ovarian lesions (p < 0.01). Mucinous cystadenomas show no distinct ADC difference to any other group of cases. However, if the highest ADC' loculus was selected as being representative, mucinous cystadenomas showed a larger ADC' value than malignant cystic neoplasms (p < 0.03). In conclusion, diffusion-weighted MRI is possibly of use in evaluating cystic contents of ovarian lesions.

Adult↗
PubMed1997

Correlation of T1 and T2 relaxation rates in normal bone-marrow water with serum ferritin concentration.

PURPOSE: This study was made to clarify the paramagnetic effect of iron stored in the hematopoietic tissue of bone marrow. MATERIAL AND METHODS: The T1 and T2 relaxation times of bone-marrow water in the L1-3 vertebrae of 20 healthy individuals were measured by MR imaging with a 1.5 T magnet. The chemical shift misregistration effect was used to isolate the bone-marrow water. The results were compared with the serum ferritin concentration. RESULTS AND CONCLUSION: Although no correlation between the T1 relaxation rate of the water fraction and the serum ferritin concentration was evident, the T2 relaxation rate of the water fraction showed strong linear correlation with the serum ferritin concentration (r = 0.87, p < 0.0001). Thus, T2 of bone-marrow water accurately reflects the amount of iron in normal bone marrow. This finding may be useful in the evaluation of the characteristics of hematopoietic tissue in bone marrow.

Adult↗
PubMed1997

Compulsory superselective arterial embolization in hypovascular local hepatic tumor ablation. Microballoon coaxial catheterization.

We performed compulsory superselective transcatheter arterial embolization on local hypovascular liver metastases under balloon occlusion using a 1-mm (3 F) coaxial microballoon catheter in 2 cases. One case was a metastasis from breast cancer (maximum diameter 5.5 cm) at segment 7. The other case comprised metastases from rectal cancer (maximum diameter 8 cm) at segments 7 and 8. Absolute ethanol (50%) mixed with Lipiodol (50%) was used for embolization. No major treatment-related complications occurred. No local recurrence was observed in either case in follow-up CT and MR studies of up to 16 and 9 months respectively. This technique may thus be applied as an alternative to surgical resection in the treatment of local hypovascular liver tumors.

Aged↗
PubMed1997

Usefulness of preoperative MRI diagnosis in prostatic adenocarcinoma.

BACKGROUND: We examined the reliability of an MRI diagnosis prior to radical prostatectomy for prostate cancer. METHODS: A radical prostatectomy was performed in 24 patients with prostate cancer. Resected specimens were fixed and 5 mm step sections vertical to the urethra were prepared to resemble MRI images. We compared this pathological map with the preoperative MRI diagnosis which included capsular or seminal vesicle invasion and tumor localization in the prostate. We defined a new criterion for the presence of capsular invasion as a chemical shift that occurred on the rectal side on T1-weighted images 5 minutes after gadolinium (Gd) enhancement and the periprostatic venous plexus was not serial. We also examined 4 diagnostic factors of tumor localization including a low-signal intensity area detected in the peripheral zone on T2-weighted images, the presence of an enhanced area on Gd-enhanced T1-weighted images, and a low T2 with either Gd-enhanced or nonenhanced T1-weighted images. RESULTS: The accuracy of a preoperative MRI diagnosis of capsular invasion was 16.7% using the conventional criteria, but 88.9% adding the new criterion. The accuracy of predicting seminal vesicle invasion was 63.2% in a group using a body surface coil compared to 75% in the group using an endorectal surface coil. The accuracy, positive predictive value, sensitivity and specificity of diagnosing tumor localization were 69%, 74.4%, 35.1%, and 91.8%, respectively. CONCLUSION: This new criterion proved superior for diagnosing capsular invasion in prostate cancer patients. Also, analysis of tumor localization in the peripheral zone demonstrated that cancer detection is increased if the low-signal intensity area is enhanced by Gd.

Adenocarcinoma↗
PubMed1997

Endothelial ATP-sensitive potassium channels mediate coronary microvascular dilation to hyperosmolarity.

Coronary arterial occlusion has been shown to increase osmolarity in the myocardial interstitium. Intracoronary injection of hyperosmolar solutions reduces coronary vascular resistance. However, the response of coronary microvessels to an abluminal increase in osmolarity is unclear, and the underlying mechanism for its vasomotor regulation has not been elucidated. In this regard, porcine coronary arterioles (81 +/- 2 microns) were isolated, cannulated, and pressurized for in vitro study. Hyperosmolarity (300-345 mosM) was produced by adding D-glucose or D-sucrose to the extravascular solution. After the arterioles developed a stable vascular tone, a graded vasodilation was observed when glucose or sucrose was incrementally administered. This hyperosmotic vasodilation was abolished after endothelial removal. Intraluminal administration of KCl (80 mM) or the ATP-sensitive potassium (KATP)-channel inhibitor glibenclamide (1 microM) to the intact vessels significantly attenuated the hyperosmotic vasodilation. Inhibition of inward rectifier potassium channels by a low concentration of BaCl2 (10 microM) did not affect vasodilation. However, a high concentration of BaCl2 (100 microM), which has been reported to inhibit KATP channels, attenuated the hyperosmotic vasodilation. Iberiotoxin (100 nM), a calcium-activated potassium (KCa)-channel inhibitor had no effect on hyperosmolarity-induced vasodilation. Inhibition of the synthesis of endothelial nitric oxide, prostaglandins, and arachidonic acid metabolites from cytochrome P-450 had no effect on hyperosmotic vasodilation. Furthermore, inhibition of vascular smooth muscle KATP channels and the large- and small-conductance KCa channels by extraluminal administration of glibenclamide, iberiotoxin, and apamin, respectively, did not alter vasodilation in response to hyperosmolarity. These results indicate that dilation of coronary arterioles in response to hyperosmotic stimulation requires an intact endothelium. However, the response is independent of the release of nitric oxide, prostaglandins, or cytochrome P-450-related endothelium-derived hyperpolarizing factor and is not a result of activation of KATP and KCa channels in vascular smooth muscle. It is suggested that the opening of KATP channels in vascular endothelium and subsequent hyperpolarization of that cell type mediate coronary microvascular dilation in response to hyperosmolarity.

Animals↗
PubMed1996

Diffuse disorder of coronary artery vasomotility in patients with coronary spastic angina. Hyperreactivity to the constrictor effects of acetylcholine and the dilator effects of nitroglycerin.

OBJECTIVES: We examined the vasomotility of the entire epicardial coronary artery system in patients with and without coronary spastic angina. BACKGROUND: The coronary arteries of patients with variant angina are hyperreactive to diverse constrictor stimuli. It is unclear whether the abnormal responses to constrictive or dilative stimuli, or both, result from a localized or diffuse disorder in the coronary artery tree. METHODS: Coronary artery diameter responses to intracoronary acetylcholine and nitroglycerin were examined at the proximal, middle and distal segments of three principal coronary arteries in 36 patients with coronary spastic angina without significant stenosis and in 12 young (< or = 30 years old) and 20 older control subjects (> 30 years old) with normal coronary arteriographic findings. In 10 patients with significant coronary stenosis, the responses of the prestenotic segments were also examined. RESULTS: In patients with coronary spastic angina, coronary spasm was induced in 23 left anterior descending, 13 left circumflex and 17 right coronary arteries by acetylcholine. Multivessel spasm was observed in 15 patients. Acetylcholine had a dilator effect on most segments in young control subjects and a mild constrictor effect in older control subjects and in patients with significant stenosis. Comparison of the responses to acetylcholine among groups demonstrated that the constrictor response of the artery with spasm was enhanced significantly and diffusely. That of the artery without spasm also tended to be enhanced. Coronary artery diameters after nitroglycerin did not differ in any segment among patients with coronary spastic angina and both control groups. In patients with coronary spastic angina, nitroglycerin significantly enhanced dilation in all segments of the artery with spasm compared with that observed in both control groups and in most segments of the artery without spasm. Patients with significant coronary stenosis had a reduced response compared with that in control subjects. CONCLUSIONS: Hyperreactive responses not only to the constrictor effects of acetylcholine, but also the dilator effects of nitroglycerin were detected diffusely in the epicardial coronary arteries of patients with coronary spastic angina. This finding indicates that a diffuse, not localized, disorder in vasomotility is involved in the pathogenesis of coronary spastic angina.

Acetylcholine↗