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Biomedical subjects

A Kurata

Publications and source records attributed to A Kurata.

At least 37 records · Page 2Linked to original sources
PubMed2000

The effect of encephalo-myo-synangiosis on abnormal collateral vessels in childhood moyamoya disease.

Child patients with Moyamoya disease initially present with ischemic symptoms. However, the long-term risk of intracranial hemorrhage for childhood Moyamoya disease is unknown. Hemodynamic overload to the fragile collateral vessels has been considered to cause hemorrhage. We reviewed angiograms to evaluate the effect of encephalo-myo-synangiosis (EMS) on abnormally dilated collateral vessels in 13 child patients with Moyamoya disease. EMS was performed on 24 sides in 13 patients ranging from 5 to 14 years of age. Post-operative angiography (6-88 months after surgery) revealed good revascularizations through EMS (larger than one-third of the middle cerebral artery (MCA) distribution) in 18 sides (75%) and smaller revascularizations in 6 sides (25%). In cases with a good revascularization through EMS, reduction of the abnormal collateral vessels was observed not only in the basal Moyamoya vessels (94% of sides) but also in the medullary arteries derived from the choroidal arteries (62% of sides), which are considered to cause intraventricular hemorrhages in adult patients. It is suggested that EMS may reduce the hemodynamic load on dilated collateral vessels and, subsequently, the long-term risk of intracranial hemorrhage in childhood Moyamoya disease.

Adolescent↗
PubMed2000

Clinicopathological study of intracranial fusiform and dolichoectatic aneurysms : insight on the mechanism of growth.

BACKGROUND AND PURPOSE: Intracranial fusiform aneurysms can be divided into 2 clinically different subtypes: acute dissecting aneurysms and chronic fusiform or dolichoectatic aneurysms. Of these 2, the natural history and growth mechanism of chronic fusiform aneurysms remains unknown. METHODS: A consecutive series of 16 patients with chronic fusiform aneurysms was studied retrospectively to clarify patient clinical and neuroradiological features. Aneurysm tissues were obtained from 8 cases and were examined to identify histological features that could correspond to the radiological findings. RESULTS: Four histological features were found: (1) fragmentation of internal elastic lamina (IEL), (2) neoangiogenesis within the thickened intima, (3) intramural hemorrhage (IMH) and thrombus formation, and (4) repetitive intramural hemorrhages from the newly formed vessels within thrombus. IEL fragmentation was found in all cases, which suggests that this change may be one of the earliest processes of aneurysm formation. MRI or CT detected IMH, and marked contrast enhancement of the inside of the aneurysm wall (CEI) on MRI corresponded well with intimal thickening. Eight of 9 symptomatic cases but none of 7 asymptomatic cases presented with both radiological features. CONCLUSIONS: Data suggest that chronic fusiform aneurysms are progressive lesions that start with IEL fragmentation. Formation of IMH seems to be a critical event necessary for lesions to become symptomatic and progress, and this can be monitored on MRI. Knowledge of this possible mechanism of progression and corresponding MRI characteristics could help determine timing of surgical intervention.

Adult↗
PubMed2000

A simple HPLC-fluorescence method for the measurement of R,S-sotalol in the plasma of patients with life-threatening cardiac arrhythmias.

R,S-sotalol, a ss-blocker drug with class III antiarrhythmic properties, is prescribed to patients with ventricular, atrial and supraventricular arrhythmias. A simple and sensitive method based on HPLC-fluorescence is described for the quantification of R,S-sotalol racemate in 500 microl of plasma. R,S-sotalol and its internal standard (atenolol) were eluted after 5.9 and 8.5 min, respectively, from a 4-micron C18 reverse-phase column using a mobile phase consisting of 80 mM KH2PO4, pH 4.6, and acetonitrile (95:5, v/v) at a flow rate of 0.5 ml/min with detection at lambdaex = 235 nm and lambdaem = 310 nm, respectively. This method, validated on the basis of R,S-sotalol measurements in spiked blank plasma, presented 20 ng/ml sensitivity, 20-10,000 ng/ml linearity, and 2.9 and 4.8% intra- and interassay precision, respectively. Plasma sotalol concentrations were determined by applying this method to investigate five high-risk patients with atrial fibrillation admitted to the Emergency Service of the Medical School Hospital, who received sotalol, 160 mg po, as loading dose. Blood samples were collected from a peripheral vein at zero, 0.5, 1.0, 1.5, 2.0, 3.0, 4. 0, 6.0, 8.0, 12.0 and 24.0 h after drug administration. A two-compartment open model was applied. Data obtained, expressed as mean, were: C MAX = 1230 ng/ml, T MAX = 1.8 h, AUC T = 10645 ng h-1 ml-1, Kab = 1.23 h-1, alpha = 0.95 h-1, ss = 0.09 h-1, t((1/2))ss = 7.8 h, ClT/F = 3.94 ml min-1 kg-1, and Vd/F = 2.53 l/kg. A good systemic availability and a fast absorption were obtained. Drug distribution was reduced to the same extent in terms of total body clearance when patients and healthy volunteers were compared, and consequently elimination half-life remained unchanged. Thus, the method described in the present study is useful for therapeutic drug monitoring purposes, pharmacokinetic investigation and pharmacokinetic-pharmacodynamic sotalol studies in patients with tachyarrhythmias.

Anti-Arrhythmia Agents↗
PubMed2000

Correlation of magnetic resonance imaging and histological findings in a large basilar tip aneurysm after coil embolization--case report.

A 73-year-old female with a large basilar tip aneurysm underwent endovascular coil embolization with interlocking detachable coils (IDCs). The patient subsequently died of pneumonia 25 days after the embolization, and the aneurysm specimen was obtained at autopsy. Histological examination showed that the intraaneurysmal structure consisted of three layers. The outer layer was mildly organized thrombus surrounding the coils, the middle layer was disorganized clot, and the inner layer consisted of fresh blood clot. Gradient-echo magnetic resonance (MR) imaging taken before death had demonstrated a central region of high intensity and a peripheral low intensity region corresponding to the inner and middle-outer layers of the aneurysm, respectively. Intraaneurysmal placement of IDCs leads to the formation of a clot surrounding the coils. However, clot formation may be inadequate where the packing of the IDCs is incomplete. Comparison of the MR imaging and histological findings in this case show that gradient-echo MR imaging can assess thrombus and residual blood flow within the aneurysm.

Aged↗
PubMed2000

Off-pump coronary artery bypass grafting for the circumflex coronary artery via the left thoracotomy in redo CABG with the patent left internal thoracic artery graft to the left anterior descending artery.

Five patients had undergone off-pump coronary artery bypass grafting (CABG) as redo CABG via the left thoracotomy for the lesions of the left circumflex coronary arteries. In all patients, the internal thoracic artery (ITA) grafts to the LAD were well patent and acting significantly important in coronary circulation, however, ischemia due to the lesion of the LCX was significant. The saphenous vein grafts or the radial artery grafts were used as the materials of the grafts. The proximal ends of these grafts were anastomosed to the descending aorta. The procedures were completed successfully in all the patients and the excellent patency was shown angiographycally even in the long-term period after the surgery. Necessity of graft surgery only for the LCX lesion would be a rare occasion for a surgeon; however, these results suggest that the procedure is simple and less risky, which would encourage the surgeon to perform it in clinical situation.

Aged↗
PubMed1999

A Retrospective Study of Breast Cancer Patients Treated with Quadrantectomy without Radiation Therapy.

BACKGROUND: Radiation therapy after breast-conserving surgery (BCS) reduces the risk of local recurrence. However, whether radiation therapy is necessary forall patients undergoing BCS remains unclear. METHODS: In order to determine the selection criteria for patients who can safely omit radiation therapy and to confirm the survival benefit of quadrantectomy without radiation therapy, we reviewed 107 patients who underwent quadrantectomy without radiation therapy between February 1988 and July 1995. RESULTS: The 5-year overall survival, disease-free survival and cumulative local recurrence rates were 93.7%, 80.7% and 12.1% respectively. There were no significant differences of 5-year overall survival (94.0% vs 94.1%) and disease-free survival rates (83.1% vs 70.0%) between patients with or without tamoxifen. The 5-year cumulative local recurrence rate of patients with tamoxifen, however, tended to be lower (p = 0.0810) than that of patients without tamoxifen. The 5-year cumulative local recurrence rate of the patients aged 45 or less was significantly higher than that of patients aged from 45 to 55 years and those over 55 (p= 0.0090 and 0.0089, respectively). In ER positive patients, the 5-year cumulative local recurrence rate of patients with tamoxifen tended to be lower (p= 0.0791) than that of patients without tamoxifen. CONCLUSION: The survival rate of quadrantectomy without radiation therapy wasacceptable. While the risk of local recurrence following quadrantectomy withoutradiation therapy is substantial, radiation therapy following quadrantectomy might not be necessary in elderly ER positive women receiving adjuvant tamoxifen therapy.

Journal Article↗
PubMed1999

Cytopathological observations in a 27-year-old female patient with endometrioid adenocarcinoma arising in the lower uterine segment of the uterus.

The determination of the malignancy of an endometrioid adenocarcinoma arising in the lower uterine segment (LUS) is difficult because of the high degree of differentiation of adenocarcinoma. The cytopathological and immunohistochemical features of endometrioid adenocarcinoma arising in the LUS of a young adult female are presented. The preoperative cytopathological examination of a 27-yr-old female could not enable an accurate diagnosis of malignancy. Hysterectomy specimens revealed the presence of an endometrioid-type adenocarcinoma with minimal atypia and myometrial invasion, which was located in the LUS. This tumor was consistent with a histological diagnosis of endometrioid minimal-deviation adenocarcinoma (MDA). Immunohistochemically, the tumor's glands were p53-, proliferating cell nuclear antigen-, and carcinoembryonic antigen-positive, and estrogen receptor-, progesterone receptor-,and vimentin-negative. The cytological and surgical specimens showed a remarkable association of squamous metaplasia. Although cytopathological difficulties in determining malignancy of MDA endometrioid adenocarcinoma arising in the LUS are well-known, the following features worth noting include: 1) squamous metaplasia on cytological and histological slides; 2) epithelial cells incorporating polymorphic nuclear neutrophils on cytological slides; and 3) positive immunohistochemistry of p53 protein. Diagn. Cytopathol. 1999;21:117-121.

Adult↗
PubMed1999

Hyperfunctioning intrathyroid parathyroid adenoma: report of two cases.

We report herein two cases of intrathyroid parathyroid adenoma, which is a rare condition in patients with hyperparathyroidism. In the first patient, an excised intrathyroid nodule was diagnosed to be parathyroid adenoma postoperatively. In the second patient, preoperative localization studies suggested the possibility of an intrathyroid adenoma. When a pathological gland is not found during surgery for primary hyperparathyroidism, an ectopic parathyroid gland including an intrathyroid adenoma should thus be considered.

Adenoma↗
PubMed1999

The factors influencing haematoma volume due to arteriovenous malformations.

Haemorrhage due to cerebral arteriovenous malformations (AVMs) varies from massive, requiring urgent operations, to clinically silent. The present study was designated to identify factors influencing haematoma size, and the pathophysiological mechanisms of massive haemorrhage were studied. 55 patients with intracerebral haematomas due to supratentorial AVMs were included in this study. Angiographic and clinical findings were retrospectively evaluated in relation to haematoma size. Statistical analysis demonstrated that small size and the presence of only one draining vein were high risk factors for massive haemorrhage. The haematoma volume in small AVMs (30 +/- 4 cm3) was significantly larger than in other AVMs (7 +/- 3 cm3) (p = 0.0005). AVMs with only one draining vein were associated with massive haematoma volume as compared to AVMs with two or more draining veins (30 +/- 4 versus 11 +/- 3 cm3, p = 0.0023). Our previous study demonstrated that feeding artery pressure (FAP) was significantly higher in AVMs with haemorrhage than in those without, as was draining vein pressure (DVP), and FAP and DVP were inversely related to the number of draining veins and the size of the AVMs. Thus, in small AVMs and AVMs with only one draining vein, local increase in DVP may thus contribute to massive haemorrhage.

Arteriovenous Malformations↗
PubMed1999

Spontaneous carotid cavernous fistulas with special reference to the influence of estradiol decrease.

The etiology of the dural arteriovenous fistula (AVF) involving the cavernous sinus is still unknown. However, it is of interest that this condition usually occurs in post-menopausal women. The purpose of the present study was therefore to clarify the relationship between sex hormone blood levels and the occurrence of dural AVFs in the cavernous sinus. Serum sex hormone levels and factors associated with atherosclerosis were examined in 26 consecutive patients with dural AVF involving the cavernous sinus presenting at our institute during the last eight years and compared with those of a post-menopause control group. Of the present patient series, 21 (81%) were women. All except five had passed menopause. Five (24%) of the women patients presented with symptoms consistent with cessation of menstruation, namely, a blood level of estradiol significantly lower than the control value. Hypertension was recognized in 10 (71%) of 14 females who had experienced menopause 10 or more years previously and in all male patients. A sudden abnormal decrease of blood estradiol levels in female patients demonstrating symptoms consistent with menopause may thus be an important precipitating factor in the occurrence of dural AVFs involving the cavernous sinus. Hypertension, in older female and male patients, with or without longstanding low blood estradiol levels, may cause atherosclerosis of the feeding vessels in the dura mater, resulting in the opening of a normal AV shunt to provide collateral circulation.

Aged↗
PubMed1999

p53 mutations in tumor and non-tumor tissues of thorotrast recipients: a model for cellular selection during radiation carcinogenesis in the liver.

Concerns over cancer development from exposure to environmental sources of densely ionizing, high linear energy transfer (LET) radiation, such as alpha-particles from radon, is a current public health issue. The study of tumors attributable to high LET irradiation would greatly augment our insights into the biological mechanisms of carcinogenesis. Chronic low-dose-rate internal exposure to alpha-radiation from thorium dioxide deposits following intravascular administration of the radiographic contrast agent Thorotrast is known to markedly increase the risk of cancer development, especially that of hepatic angiosarcomas and cholangiocarcinomas. Although the mechanism is hypothesized to be via cellular damage, DNA being a major target, wrought by the high LET alpha-particles, the specific genes and the actual sequence of events involved in the process of transforming a normal cell into a malignant one are largely unknown. To shed some light on the molecular mechanisms of cancer development during a lifetime exposure to alpha-radiation, we analyzed the most commonly affected tumor suppressor gene in humans, p53, in 20 Thorotrast recipients who developed cancer, mostly of hepatic bile duct and blood vessel origin. Of the 20 cases, 19 were found to harbor p53 point mutations. Moreover, the accompanying non-tumor tissues from these patients also had p53 mutations, albeit at lower frequency. The distribution pattern of the point mutations was significantly different between the non-tumor and tumor tissues, with most mutations in malignant tissues located in the highly conserved domains of the p53 gene. Our results support the idea that p53 mutations are important in the genesis of Thorotrast-induced tumors but that these point mutations are a secondary outcome of genomic instability induced by the irradiation. Additionally, non-tumor cells harboring p53 mutations may gain some survival advantage in situ but mutations in the domains responsible for the formation of structural elements critical in binding DNA may be necessary for a cell to reach full malignancy.

Aged↗
PubMed1999

Purification, molecular cloning, and genomic organization of human brain long-chain acyl-CoA hydrolase.

An acyl-CoA hydrolase, referred to as hBACH, was purified from human brain cytosol. The enzyme had a molecular mass of 100 kDa and 43-kDa subunits, and was highly active with long-chain acyl-CoAs, e.g. a maximal velocity of 295 micromol/min/mg and K(m) of 6.4 microM for palmitoyl-CoA. Acyl-CoAs with carbon chain lengths of C(8-18) were also good substrates. In human brain cytosol, 85% of palmitoyl-CoA hydrolase activity was titrated by an anti-BACH antibody, which accounted for over 75% of the enzyme activity found in the brain tissue. The cDNA isolated for hBACH, when expressed in Escherichia coli, directed the expression of palmitoyl-CoA hydrolase activity and a 44-kDa protein immunoreactive to the anti-BACH antibody, which in turn neutralized the hydrolase activity. The hBACH cDNA encoded a 338-amino acid sequence which was 95% identical to that of a rat homolog. The hBACH gene spanned about 130 kb and comprised 9 exons, and was mapped to 1p36.2 on the cytogenetic ideogram. These findings indicate that the long-chain acyl-CoA hydrolase present in the brain is well conserved between man and the rat, suggesting a conserved role for this enzyme in the mammalian brain, and enabling genetic studies on the functional analysis of acyl-CoA hydrolase.

Adult↗
PubMed1999

Tissue response of a small saccular aneurysm after incomplete occlusion with a Guglielmi detachable coil.

A 49-year-old woman had a small saccular aneurysm that was incompletely occluded with a Guglielmi detachable coil (GDC). She died from rupture of another aneurysm 42 days after the treatment. Autopsy for the embolized aneurysm revealed no neoendothelium at the aneurysmal neck, but an organized thrombus was observed limited to the periphery of the aneurysmal lumen. Although isolation of the aneurysm was not apparent, loose embolization with this method may help to reinforce the aneurysmal wall.

Aneurysm, Ruptured↗
PubMed1998

Gain-of-function mutations of c-kit in human gastrointestinal stromal tumors.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in the human digestive tract, but their molecular etiology and cellular origin are unknown. Sequencing of c-kit complementary DNA, which encodes a proto-oncogenic receptor tyrosine kinase (KIT), from five GISTs revealed mutations in the region between the transmembrane and tyrosine kinase domains. All of the corresponding mutant KIT proteins were constitutively activated without the KIT ligand, stem cell factor (SCF). Stable transfection of the mutant c-kit complementary DNAs induced malignant transformation of Ba/F3 murine lymphoid cells, suggesting that the mutations contribute to tumor development. GISTs may originate from the interstitial cells of Cajal (ICCs) because the development of ICCs is dependent on the SCF-KIT interaction and because, like GISTs, these cells express both KIT and CD34.

Amino Acid Sequence↗