Biomedical subjects

S Sakaki

Publications and source records attributed to S Sakaki.

At least 19 recordsLinked to original sources

PubMed2004

Co-existence of unruptured cerebral aneurysms in patients with hypertensive intracerebral hemorrhage.

OBJECTIVE: Primary hypertensive intracerebral hemorrhage (PICH) is caused by a rupture of a small endartery, and diagnosis is made either by computed tomography (CT) or magnetic resonance imaging (MRI). Vascular abnormalities are not always evaluated in detail. In this study, we aimed to clarify the incidence of co-existing vascular abnormalities, especially unruptured cerebral aneurysms by reviewing selective intraarterial digital subtraction angiography (DSA) images in PICH patients. METHODS: The cases of 169 hypertensive PICH patients who underwent selective intra-arterial DSA were reviewed. In all cases, CT or MRI showed no abnormality other than PICH, such as subarachnoid hemorrhage, component of arterio-venous malformation or cerebral tumor. The main reason for performing DSA was to exclude other causes of intracerebral hemorrhage such as ruptured cerebral aneurysm or small arterio-venous malformation prior to surgical removal of the hematoma. RESULTS: There were 33 patients with vascular abnormalities: unruptured cerebral aneurysm (n = 24, 14.2%), major vessels occlusion or stenosis (n= 8, 4.7%), and dural arterio-venous fistula (n = 1). Unruptured cerebral aneurysms were found in 9.4% of men and 20.5% of women. CONCLUSION: Vascular abnormalities co-existing with PICH are not rare, suggesting the necessity for angiographic evaluation. Special attention should be given to female PICH patients who have a high incidence of having an unruptured cerebral aneurysm.

Adult↗

PubMed2001

The role of interventional radiology in the management of blunt renal injury: a practical protocol.

OBJECTIVE: The purpose of this study was to evaluate the efficacy of a protocol designed to minimize the need for surgery in the management of severe blunt renal injury. METHODS: Forty-six of 752 trauma patients had evidence of renal injury on computed tomographic (CT) scan. Two patients required emergency laparotomy, and the remaining 44 patients were classified by CT scan grade using the American Association for the Surgery of Trauma classification system. Patients with CT scan grade 3 or over underwent renal angiography. RESULTS: Twenty-one patients had a high-grade injury on CT scan (> or =3). Eight had angiographic evidence of extravasation from renal arterial branches and underwent transarterial embolization. One patient with a grade 5 injury had extravasation from a main renal vein and underwent immediate laparotomy. This was the only patient who required surgery for renal injury. CONCLUSION: Surgery can be avoided in most cases of blunt renal injury. Hemodynamic instability and injury to main renal veins remain indications for surgical exploration.

Abdominal Injuries↗

PubMed2001

Discrimination of brain abscess and cystic tumor by in vivo proton magnetic resonance spectroscopy.

Proton magnetic resonance (MR) spectroscopy was evaluated for the differentiation of brain abscesses and cystic brain tumors. Proton MR spectroscopy was performed in vivo in two patients with brain abscess and eight patients with various cystic brain tumors (anaplastic astrocytoma, glioblastoma, and metastatic brain tumor). MR imaging with contrast medium demonstrated ring-like enhanced mass lesions in all patients. The various resonance peaks in proton MR spectra were assigned to metabolites according to chemical shifts. Treatment of the cystic brain lesions was based on the information from proton MR spectroscopy. Aspirated pus from one patient with brain abscess was examined using ex vivo proton MR spectroscopy. The in vivo spectra of brain abscess contained resonance peaks attributed to acetate, lactate, alanine, amino acids, and lipids in both cases, and an additional peak of succinate in one case. In vivo spectra of the neoplasms contained resonance peaks corresponding to lactate, lipids, choline, creatine, and N-acetyl aspartate. Proton MR spectroscopy is useful for discriminating brain abscess from cystic tumors with similar neuroimaging appearance, which is very important for determining the treatment strategy.

Acetates↗

PubMed2001

Prediction of tissue survival after middle cerebral artery occlusion based on changes in the apparent diffusion of water.

OBJECT: In this study the authors tested the hypothesis that the estimate of the apparent diffusion coefficient (ADC) of water is a reliable pathophysiological index of the viability of ischemic brain tissue. METHODS: Cerebral blood flow (CBF) and the cerebral metabolic rates of oxygen and glucose (CMRO2 and CMRglc, respectively) were measured using positron emission tomography (PET) scanning before and after permanent middle cerebral artery occlusion (MCAO) or reperfusion in pigs. The ADC value, which was measured using diffusion-weighted magnetic resonance (DW MR) imaging was compared with physiological variables obtained by PET scanning and with histological findings. After both permanent MCAO and reperfusion, the decrease in the ADC was significantly correlated with decrease in the CMRO2 and CMRglc. The infarction coincided with a CMRO2 threshold of 50% of the value measured on the contralateral side. Thus, an ADC value of 80% or 75% of the contralateral value reflected the CMRO2 threshold after permanent MCAO or reperfusion, respectively. On DW MR images, lesions with ADC values above 80% of the contralateral value are potentially reversible until 6 hours after MCAO, whereas lesions with ADC values below 75% of the contralateral value are irreversible as early as 2 hours after MCAO. CONCLUSIONS: The ADC of water provides a reliable pathophysiological index for tailoring therapy to the condition of individual stroke patients in clinical practice.

Animals↗

PubMed2000

Histochemical cytochrome c oxidase activity and caspase-3 in gerbil hippocampal CA1 neurons after transient forebrain ischemia.

We examined the cytochrome c oxidase (COX) activity in gerbil hippocampal CA1 neurons after 5-min ischemia by a histochemical method in the presence or absence of exogenous cytochrome c. In the CA1 neurons, COX activity without exogenous cytochrome c decreased from 1 h after ischemia, but was restored by the addition of exogenous cytochrome c in the following 6 h after ischemia. These results suggest that it is not COX activity but endogenous cytochrome c that is changed in the early phase after ischemia, and that COX activity begins to decrease 9 h after ischemia. We examined caspase-3 in the CA1 region by immunoblotting, as caspase-3 is known to take part in the cell-death cascade downstream from cytochrome c. Although pro-caspase-3 was strongly detected, active caspase-3 was not detected before and until 84 h after 5-min ischemia. Our data suggested that delayed neuronal death is likely to progress via cytochrome c-release but not via caspase-3 activation.

Animals↗

PubMed2000

Cytochrome c release from mitochondria to the cytosol was suppressed in the ischemia-tolerance-induced hippocampal CA1 region after 5-min forebrain ischemia in gerbils.

Cytochrome c was detected by immunoblotting in the cytosolic fraction 3 h after 5-min ischemia in the non-ischemia-tolerant CA1 region in which about 96% of neurons had developed delayed neuronal death, while less cytosolic cytochrome c was detected in the ischemia-tolerance-induced CA1 region where many more neurons survived. In the immunohistochemical study using anti-non-native cytochrome c monoclonal antibody, immunoreactivity was observed throughout the cytoplasm in the non-ischemia-tolerant CA1 neurons, but not in the normal and ischemia-tolerant CA1 neurons. Then we determined whether Bcl-2, Bax, Bcl-xL and Bcl-xS, which regulate the release of cytochrome c from mitochondria, were altered in the ischemia-tolerant CA1 region. Bcl-2 and Bax were up-regulated in the ischemia-tolerant group, but Bcl-xL and Bcl-xS showed no apparent difference in their expression. These results suggest that cytochrome c release is prevented in CA1 neurons in gerbils in which ischemia-tolerance had been induced and that the altered ratio of Bcl-2 to Bax may play a part in this mechanism.

Animals↗

PubMed2000

Selection of surgical approaches for small acoustic neurinomas.

BACKGROUND: The purpose of this study was to evaluate the results of surgery for small acoustic neurinomas at our institute via the middle cranial fossa and retrosigmoid approaches, and to determine the indications for each approach. METHODS: Fifty-three patients with unilateral tumors less than 2 cm in diameter were studied. Surgery was performed via the middle cranial fossa approach in 36 tumors and via the retrosigmoid approach in 17 tumors. RESULTS: The hearing preservation rate was 68% (36/53) in all patients, 93% (14/15) in patients with intracanalicular tumors, 79% (15/19) in patients with tumors less than 1 cm in diameter, and 43% (7/19) in patients with tumors between 1 and 2 cm in diameter. The facial nerve function was excellent or good in 80% (42/53), 74% (11/15), 84% (16/19), and 78% (15/19), respectively. Among the 19 patients with tumors between 1 and 2 cm in diameter, the frequencies of hearing preservation and of excellent or good facial nerve function (47% and 87%, respectively) in the 15 patients approached via the retrosigmoid approach were higher than those (0% and 50%, respectively) in the four patients approached via the middle cranial fossa approach. CONCLUSIONS: We conclude that tumors smaller than 2 cm should be removed because preservation of hearing as well as facial nerve function may be possible in almost all of these patients. Tumors larger than 1 cm should be surgically treated through the retrosigmoid approach.

Adult↗

PubMed2000

Transvenous embolization of carotid-cavernous sinus fistula associated with a primitive trigeminal artery--case report.

A 58-year-old female presented with right conjunctival chemosis and right abducens nerve paresis. Cerebral angiography demonstrated a right carotid-cavernous sinus fistula associated with persistent primitive trigeminal artery. The fistula was treated by introducing detachable coils through the transvenous approach, as the detachable balloon was not available. Follow-up angiography performed 14 days after the embolization revealed complete disappearance of the carotid-cavernous sinus fistula due to thrombosis, which was presumably accelerated by the coils. Transvenous coil embolization should be considered as an alternative treatment for high-flow carotid-cavernous sinus fistula, but only if transarterial balloon embolization is not successful or unavailable.

Arteries↗

PubMed2000

Neuroprotective effect of postischemic administration of progesterone in spontaneously hypertensive rats with focal cerebral ischemia.

OBJECT: Exogenous progesterone has been shown to reduce brain edema and ischemia-induced cell damage and to improve physiological and neurological function during the early stage of focal cerebral ischemia. In the present study, the authors assessed the neuroprotective potential of progesterone during the late stage of ischemia in a transient middle cerebral artery (MCA) occlusion model in the rat. METHODS: Forty-eight male spontaneously hypertensive rats were randomly assigned to six groups. Progesterone was dissolved in dimethyl sulfoxide (DMSO). In four groups of rats, the dissolved progesterone (4 mg/kg or 8 mg/kg) was administered for 2 or 7 days after ischemia. In two control groups DMSO was administered for 2 or 7 days after ischemia. Occlusion of the MCA was induced by insertion of an intraluminal suture, and reperfusion was accomplished by withdrawal of the suture. Treatment was initiated on reperfusion, which followed 2 hours of MCA occlusion, and continued once a day. Lesion volume, neurological deficit, and body weight loss were measured 2 or 7 days after ischemia, depending on the animal group. Treatment with a high dose of progesterone (8 mg/kg) resulted in reductions in lesion size, neurological deficits, and body weight, compared with control rats. CONCLUSIONS: Administration of progesterone to male rats 2 hours after MCA occlusion reduces ischemic brain damage and improves neurological deficit even 7 days after ischemia.

Analysis of Variance↗

PubMed2000

Relationship between residual cerebral blood flow and oxygen metabolism as predictive of ischemic tissue viability: sequential multitracer positron emission tomography scanning of middle cerebral artery occlusion during the critical first 6 hours after stroke in pigs.

OBJECT: The authors tested the hypothesis that oxygen metabolism is the key factor linking the long-term viability of ischemic brain tissue to the magnitude of residual blood flow during the first 6 hours following a stroke. METHODS: Eleven anesthetized pigs underwent a series of positron emission tomography studies to measure cerebral blood flow (CBF) and metabolism before and for 7 hours after the animals were subjected to permanent middle cerebral artery (MCA) occlusion. The extent of collateral blood supply was assessed using angiography. Abnormal metabolism of the ischemic tissue progressed as a function of time in inverse proportion to the magnitude of residual CBF, and the volume of the infarct grew in inverse proportion to the residual blood supply. Ten hours after occlusion of the MCA, the infarct topographically matched the tissue with a cerebral metabolic rate of oxygen consumption below 50% of values measured on the contralateral side. This was also the threshold for the decline of the oxygen extraction fraction below normal, which was critical for the prediction of nonviable ischemic tissue. Mildly ischemic tissue (CBF > 30 ml/100 g/min) did not reach the cerebral metabolic rate of oxygen threshold of viability during the first 6 hours after MCA occlusion; moderately ischemic tissue (CBF 12-30 m1/100 g/ min) reached the threshold of viability in 3 hours; and severely ischemic tissue (CBF < 12 ml/100 g/min) remained viable for less than 1 hour. CONCLUSIONS: The relationship between the residual CBF and both oxygen metabolism and extraction is critical to the evolution of metabolic deficiency and lesion size after stroke.

Animals↗

PubMed2000

[Evaluation of hemodynamics in cerebral infarction using MRI with FAIR sequence].

In comparison with 99mTc-ECD SPECT, the usefulness for evaluation of cerebral blood flow by the perfusion images using MRI with FAIR sequence was studied in ischemic stroke patients. Among 27 cases, 15 patients showed lacunar infarctions and 12 patients showed cortical infarctions determined by T2 weighted MR images. FAIR images were obtained as single images at the slice position running through the basal ganglia or corona radiata. The inversion times(TI) were varied, ranging from 800 to 1,400 msec. In 15 patients without definite low perfusions in the SPECT study, FAIR images showed sequentially proxymal arterial branches in early phase and distal arterial branches or capillary beds in the cortical tissues in a late phase as the TI was elongated. Nine of the 12 patients with low cerebral perfusions in the SPECT study showed perfusion defects in FAIR imaging. Five of the 12 patients with a small low cerebral perfusion area in the SPECT study showed a delay of the depiction of cortical arteries along with TI elongation. In 3 patients, ischemic lesions demonstrated by the SPECT study was not shown in the MRI study because of motion artifacts. In conclusion, FAIR imagings are considered to be useful in the evaluation of cerebral flow dynamics in the ischemic stroke patients.

Aged↗

PubMed2000

[A case of adult moyamoya disease progressed after vascular reconstructive surgery].

We report an adult onset patient with moyamoya disease showing acute progress after contralateral vascular reconstructive surgery. A 47-year-old female developed cerebral infarction in the left corona radiata. A magnetic resonance (MR) angiography and a cerebral angiogram revealed severe stenosis extending from the terminal portion of left internal carotid artery (ICA) to the M1 portion. The right ICA showed slight stenosis. We performed direct bypass surgery (STA-MCA anastomosis) on the affected left side. MR angiography 1 month after surgery revealed the progressive stenosis of the C1 portion of the right ICA. While measurement of cerebral blood flow (CBF) showed a slight impairment of vascular reactivity to acetazolamide loading in the region of the right MCA, we continued without vascular reconstructive surgery for the right side because there was no ischemic attack. The patient had a transient sensory disturbance of the left upper extremity 16 months after surgery. MR angiography and a cerebral angiogram revealed more progressive stenosis extending from the right ICA to the M1 portion. CBF study showed a low CBF at rest and a negative response to acetazolamide loading in the region of the right MCA. Direct bypass surgery was performed on the right hemisphere. Follow-up study revealed an increment of rest CBF and improvement of vascular reactivity. We underlined the necessity for careful postoperation observation of progressive contralateral arterial stenosis using MR angiography and CBF study in adult onset patients with moyamoya disease.

Cerebral Angiography↗

PubMed2000

Assessment of perioperative predictive factors influencing survival in patients with postinfarction ventricular septal perforation. Classified by the site of myocardial infarction.

BACKGROUND: The present study was designed to identify the perioperative factors and to consider a counterplan for the improvement of surgical results, based on the site of myocardial infarction. METHODS: Sixteen patients with postinfarction ventricular septal perforation underwent surgical repair. The operation was performed 5+/-3 days after the onset of ventricular septal perforation using the same method, an infarctectomy and reconstruction of the septum and right and left ventricular walls with a single Dacron patch. The ventricular septal perforation was anterior in 11 patients and posterior in 5. Preoperative hemodynamics between survivors and non-survivors were compared. Left ventricular wall motion was estimated using echocardiography by wall motion score (divided into 17 segments and each segment was graded on a fourpoint scale: normal, 0; hypokinetic, 1; severe hypokinetic, 2; a- or dyskinetic, 3) and summed up. RESULTS: The operative mortality was 36% in 11 patients with anterior ventricular septal perforation. In non-survivors compared to survivors, wall motion score was greater (25+/-4 vs 18+/-4, p<0.01) and all values were over 20. The value of the cardiac index divided by Qp/Qs was lower (0.98+/-0.09 vs 1.44+/-0.31, p<0.02) and all were under 1.1. In 5 patients with inferior ventricular septal perforation, the operative mortality was 40%. In non-survivors compared to survivors, wall motion score was greater (18, 18 vs 7, 2, 12) and the right atrial pressure was greater (18, 19 vs 10, 9, 9 mmHg) due to a right ventricular infarction. CONCLUSIONS: The patients with poor left ventricular wall motion were lost for reasons unrelated to the site of myocardial infarction. Moreover, a cardiac index over Qp/Qs in anterior ventricular septal perforation and the existence of a right ventricular infarction in inferior ventricular septal perforation was predictive of operative mortality.

Aged↗

PubMed1999

Stabilization of an antibody conjugated with enzyme by 2-methacryloyloxyethyl phosphorylcholine copolymer in enzyme-linked immunosorbent assay.

The purpose of this study was to develop a novel synthetic stabilizer of enzyme-linked antibody in the enzyme-linked immunosorbent assay (ELISA). The water-soluble amphiphilic phospholipid polymer, poly[2-methacryloyloxyethyl phosphorylcholine (MPC)-co-styrene (St)] was synthesized, and its stabilizing functions for the antibody were compared with conventional stabilizers of the antibody conjugated with enzyme (enzyme-antibody conjugate), such as bovine serum albumin (BSA) and casein. In the absence of the stabilizer, the remaining immunologic activity decreased to about 10% of its initial value after 37 days. The same tendency was observed even when the enzyme-antibody conjugate in 1.0 wt % BSA solution was used as a stabilizer. In 1.0 wt % casein solution, the immunologic activity decreased to 29% of the initial value after 37 days. On the other hand, in 0.1 wt % and 1.0 wt % poly(MPC-co-St) solution, the activity remained 74% and 92% of the initial value, respectively. The effects of poly(MPC-co-St) on the stabilization of the enzyme-antibody conjugate depended on the concentration of poly(MPC-co-St). During the ELISA procedure, not only did poly(MPC-co-St) have no effect on the reaction between the antigen and the antibody, but it also had no effect on the reaction between the enzyme and the substrate. These results indicate that poly(MPC-co-St) has the ability to suppress the denaturation of protein, enzyme, and antibody. We concluded that water-soluble poly(MPC-co-St) is an effective synthetic stabilizer in the ELISA.

Animals↗

PubMed1999

Release of cytochrome c from mitochondria to cytosol in gerbil hippocampal CA1 neurons after transient forebrain ischemia.

We examined cytosolic cytochrome c in gerbil hippocampal CA1 and CA3 regions after induction of 5-min ischemia by immunoblotting. In the CA1 region, cytochrome c was detected in the cytosolic fraction from 1 to 6 h after ischemia by Western blotting, while it was not detected in the CA3 region. Following intraventricular administration of cyclosporin A (CsA), detectable cytosolic cytochrome c was dramatically decreased, and about 80% of CA1 neurons survived after ischemia. The present studies demonstrate that cytochrome c is translocated from mitochondria to the cytosol in the early stage of delayed neuronal cell death, and suggest the involvement of the mitochondrial permeability transition.

Animals↗

PubMed1999

Increase in p53 protein expression following cortical infarction in the spontaneously hypertensive rat.

Using stroke-prone spontaneously hypertensive (SH-SP) rats with permanent occlusion of the middle cerebral artery (MCA), we investigated the expression of wild type p53 (wt-p53) protein and the occurrence of DNA fragmentation in cerebral neurons after ischemia. Three days following MCA occlusion, terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL staining) revealed a distinct pattern of nuclear staining in many neurons around the ischemic core. On the lesioned side of the cerebral cortex one day after MCA occlusion, wt-p53 immunoreactivity was observed specifically in the cortical neurons, in the same regions as the TUNEL staining. Mutant type p53 (mt-p53) immunoreactivity was not observed at any time following MCA occlusion. These findings suggest that wt-p53 dependent cell death of cortical neurons occurred in the ischemic periphery following cerebral ischemia and that this pathway for the induction of cell death may play an important role in the exaggeration of cerebral ischemic injury.

Animals↗

PubMed1999

Restoration of wild-type p16 down-regulates vascular endothelial growth factor expression and inhibits angiogenesis in human gliomas.

Recent studies have indicated that the loss of p16 is a frequent event in the progression of malignant gliomas. The loss of p16 promotes the acquisition of malignant characteristics in gliomas, which are among the most angiogenic of all human tumors. High-grade gliomas are distinguished from low-grade gliomas by intense angiogenesis in addition to their frequent loss of p16. New therapeutic strategies aimed at inhibiting tumor angiogenesis on the basis of molecular mechanisms are theoretically attractive. Here we evaluate the effect of p16 gene replacement on the angiogenesis of gliomas. Infection with a recombinant replication-defective adenovirus vector containing the cDNA of wild-type p16 significantly reduced the expression of vascular endothelial growth factor, which is thought to be a pivotal mediator of tumor angiogenesis, in p16-deleted glioma cells. Restoring wild-type p16 expression into p16-deleted glioma cells markedly inhibited angiogenesis induced by tumor cells in vivo. Furthermore, wild-type p16 inhibited neovascularization more potently than did wild-type p53 transfer. These findings indicate that the p16 gene plays an important role in the regulation of glioma angiogenesis, suggesting a novel function of the p16 gene.

Adenoviruses, Human↗

PubMed1999

Diagnostic use of isotropic diffusion-weighted MRI in patients with ischaemic stroke: detection of the lesion responsible for the clinical deficit.

We examined the diagnostic use of isotropic diffusion-weighted (DW) MRI in 140 consecutive patients suspected of or diagnosed as having an ischaemic stroke. Isotropic DW imaging could demonstrate the lesion responsible for the clinical deficit in patients with multiple cerebral infarcts at an early stage, even small lesions without a perifocal oedema or mass effect. Accurate diagnosis by DW images may, however, be difficult about 2 weeks after the onset of stroke.

Adult↗