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Biomedical subjects

N Sakai

Publications and source records attributed to N Sakai.

At least 325 records · Page 18Linked to original sources
PubMed1997

[Clinical application of 31P-chemical shift image using 31P-volume coil to Moyamoya disease].

31P-MRS and 31P-Chemical Shift Image(CSI) using volume coil were applied to Moyamoya disease of 14 cases, data of which were compared with clinical manifestations and neuroimagings. In four asymptomatic cases, signal intensity of both total P and total ATP was almost equal in each voxel, but in other cases, both signal intensity of the lesion was relatively decreased, compared with non-lesion. Especially, signal intensity of total P and total ATP in ischemic lesion was significantly decreased. This showed that 31P-CSI is able to demonstrate cerebral ischemic lesion not detected by CT and MRI. We have reported on Moyamoya disease that 31P-MRS comparatively correlates to cerebral blood flow and 31P-CSI demonstrates ischemic lesion as not detected by CT and MRI less invasively.

Cerebrovascular Circulation↗
PubMed1997

Standardization of low attenuation area versus total lung area in chest X-ray CT as an indicator of chronic pulmonary emphysema.

We examined the methods for measuring the LAA% (100 x low attenuation area/total lung area) on thoracic X-ray CT scans in order to develop a useful indicator of chronic pulmonary emphysema (CPE). First, we modified the method for calculating the LAA% to be applicable by the programming tool installed in a commercially available CT machine in order to minimize manual procedures. This new method proved to be applicable in all CT machines produced after 1987. Second, we examined the difference in the Hounsfield Unit (HU) between different CT machines using two kinds of phantoms. One phantom was composed of Styrofoam, which has a density similar to the low attenuation areas. The other phantom was composed of Styrofoam and water, which has a density similar to the lung. We proved that the difference of LAA% with the correct value was 5% at maximum among four different CT machines. Thus, the phantom developed in the present study may play an important role in the standardization of HU. Finally, the possibility of decreasing the X-ray levels was examined. Twenty-five percent of the standard electrical current provided the same LAA% in cases where the subject was an established CPE patient, whereas the LAA% was overestimated in subjects with a normal LAA% value. However, a correction using a linear regression equation may be possible in the latter cases. It may be concluded that LAA% analysis can easily be performed in many city hospital, without much investment of manual procedures or any corrections to the HU levels between different CT machines. This method may be useful as a routine follow up for CPE patients because of the smaller irradiated dose given when using a CT machine.

Algorithms↗
PubMed1997

[A case of cavernous dural arteriovenous fistula resulting in intracerebral extravasation during transvenous embolization].

Cortical venous drainage has been described as one of the major risk factors for dural arteriovenous fistula, which may induce venous hypertension leading to venous ischemia or intracerebral hemorrhage. However, it is rather rare to observe cortical venous drainage manifesting in this way in the cavernous sinus region. We report a case of a 55-year-old gentleman with a right cavernous dural arteriovenous fistula, presenting with conjunctival chemosis, exophthalmus and ocular hypertension on the affected side. Magnetic resonance imaging showed a small intracerebral hemorrhage in the right frontal lobe. Cerebral angiography revealed a dural arteriovenous fistula in the right cavernous sinus draining into the right olfactory vein via the uncal vein, as well as into the superior and inferior ophthalmic veins. This unusual cortical venous reflux was thought to be consistent with the intracerebral hemorrhage found on the magnetic resonance imaging. The patient underwent transvenous embolization for the dural arteriovenous fistula using an inferior petrosal catheterization into the uncal vein was difficult, and the cortical venous reflux through the vein seemed to be slight. However, extravasation of the contrast material occurred in the right frontal lobe after obliteration of the ophthalmic veins during the procedure. The cause of the extravasation was suspected to be the same olfactory vein that had been involved in the previous intracerebral hemorrhage. The obliteration of the dural fistula was continued rapidly, and the fistula disappeared after the embolization. Neurologically, the patient had no noticeable troubles, except for a mild headache. The pretreatment symptoms were alleviated within several days, and the patient was discharged in a week. We emphasize the following points from this rare case in order to facilitate a safer procedure during transvenous embolization for cavernous dural arteriovenous fistula. It is important to obliterate the cortical venous drainage as early as possible, even if the reflux is small or the catheterization is difficult. Repeated, careful sinography is useful for the evaluation of the drainage pattern at certain stages during the transvenous embolization procedure.

Arteriovenous Fistula↗
PubMed1997

Tensile stress of the lateral patellofemoral ligament during knee motion.

Abnormal patellar retinacular tension has been considered to result in patellar lateral subluxation/dislocation. In this study, an in vitro experimental model was developed to determine the tensile stress of the lateral patellofemoral ligament, the thickest portion of the retinaculum, under loading conditions simulating two knee motion patterns: passive knee motion and unweighted active knee extension. The results indicate that the tensile stress increased significantly before 30 degrees of knee flexion, which strongly supports the clinical findings that patellar subluxation/dislocation occurs at approximately 20 degrees to 30 degrees knee flexion angles.

Analysis of Variance↗
PubMed1997

[Tumor suppressive function of gelsolin].

We examined the expression of gelsolin in a murine ras tumor and a number of human stomach, colon, bladder, and lung cancer cell lines and tissues. In most of the cell lines and tumor tissues, gelsolin expression was undetectable or extremely low in comparison with its expression in normal epithelial cells. Upon the introduction of the exogenous human wild-type gelsolin cDNA into human cancer cell lines, the gelsolin transfectants had greatly reduced colony-forming ability and tumorigenicity in vivo. After UVC irradiation, the gelsolin-overexpressing bladder cancer cells demonstrated increased accumulation and/or protracted delay in G2 phase as compared to neotransfected cells. UVC-induced production of diacylglycerol was reduced in gelsolin-overexpressed UMUC-2 cells as compared to neo-transfected UMUC-2 cells. Levels of cyclin B in the synchronized and gelsolin-overexpressing UMUC-2 cells remained low during the G2 delay. To investigate the in vivo efficacy of gene therapy with the gelsolin tumor suppressor, we treated human urinary bladder cancers (UMUC-2 and DAB-1), inoculated in nude mice, with recombinant retrovirus packaging cells containing the human gelsolin cDNA. This gene therapy resulted in remarkable tumor growth inhibition, and prolonged survival time in the majority of animals. These observations suggest that gelsolin plays a key role as a tumor suppressor by regulating a G2 checkpoint function of cancer cells through phosphoinositol lipid metabolism, and demonstrate the potential of using the gelsolin tumor suppressor in human urinary bladder carcinoma.

Animals↗
PubMed1997

Adenovirus-mediated expression of hepatic lipase in LCAT transgenic mice.

In order to evaluate the coordinate role that hepatic lipase (HL) and lecithin:cholesterol acyltransferase (LCAT) play in modulating HDL particle heterogeneity and function in vivo we utilized recombinant adenovirus to express HL in control and LCAT transgenic mice. Adenovirus-mediated expression of human HL in control (n = 4, LCAT activity = 42 +/- 1 nmol/ml per h) and LCAT-tg mice (n = 4, LCAT activity = 3566 +/- 93 nmol/ml per h) resulted in post heparin HL activities of 24,358 +/- 6080 and 27,266 +/- 7985 nmol/ml per min, respectively. Overexpression of HL led to significant reductions in total cholesterol, phospholipids, and HDL cholesterol in both LCAT-tg (62, 62, and 63%, P < 0.05) and control mice (68, 63, and 78%, P < 0.01) as well as to the formation of more homogenous HDL. However, compared to control animals, the reductions in the plasma concentrations of HDL-cholesterol and apoA-I were less in LCAT-tg mice (HDL-cholesterol: -62 +/- 15% vs. -78 +/- 15%, P = 0.18; apoA-I: -36 +/- 7% vs. -76 +/- 8%, P < 0.0005). Gel filtration analysis revealed that in LCAT-tg mice the apoE-rich HDL1 was preferentially reduced by expression of HL in vivo. Compared to control mice the reduction in the apoA-I/A-II HDL in transgenic mice was significantly less indicating that a subset of HDL in LCAT transgenic mice are resistant to the action of HL. These combined data support a role for both HL and LCAT in modulating HDL heterogeneity and function, properties which may ultimately affect the ability of LCAT transgenic mouse HDL to function in the process of reverse cholesterol transport.

Adenoviridae↗
PubMed1997

[Central nervous system metastasis from non-functioning adrenocortical carcinoma: report of a case].

We report a rare case of brain tumor metastasizing from an adrenocortical carcinoma. A 47-year-old man was referred to our department on September 21, 1995, with complaints of episodic loss of consciousness and severe left motor weakness. There was a past history of left adrenalectomy performed in the Department of Surgery of our hospital 9 months before. On admission, computed tomography (CT) and magnetic resonance imaging (MRI) revealed two well circumscribed masses in the right frontal lobe with peritumoral, marked brain edema and metastasis to the lung. The brain tumor was successfully removed via frontal craniotomy 4 days after admission. Histological examination of the tumor specimen revealed metastatic anaplastic cell carcinoma, indicating metastasis from an adrenocortical carcinoma. After chemotherapy with cisplatin, pepleomycin and pirarubicin, he was discharged without neurological deficit. Two months postoperatively, however, the patient received 50 Gy of telecobalt radiation therapy to the whole brain because of recurrence. Three months after-wards, the patient returned complaining of general fatigue. Chest CT scan revealed further enlargement of the lung lesions. Despite repeated chemotherapy, the patient died of lung metastases eight weeks later. Central nervous system metastasis from adrenocortical carcinoma is exceedingly rare. To the best of our knowledge, only 5 cases have been reported. We report here another case of brain metastasis from adrenocortical carcinoma possibly via lung metastasis, and review the pertinent medical literature.

Adrenal Cortex Neoplasms↗
PubMed1997

[A case of chronic necrotizing pulmonary aspergillosis successfully treated with combination therapy of antifungal drugs and ulinastatin].

A 64-year-old woman with a history of old tuberculosis, had a fungus ball shadow with meniscus sign in the upper right lung field on a chest X-ray film in 1991. Based on the chest X-ray findings, pulmonary aspergilloma was suspected. Because the size of the intracavitary fungus ball increased, the patient was treated with itraconazole over one year in 1995, but there was no improvement. One month later, she was admitted because of fever, hemoptysis and productive cough, and chest X-ray showed an enlargement of intracavitary mass and infiltrative shadow in the right lung. Chronic necrotizing aspergillosis was diagnosed on the basis of her clinical and radiographic features, and positive serological test. Although itraconazol and amphotericin B were given, cavity and intracavitary fungus ball shadow kept growing. Combination therapy of antifungal drugs and ulinastatin markedly improved symptoms and resulted in complete disappearance of the fungus ball on chest CT scan.

Amphotericin B↗
PubMed1997

Expression of GCF protein is dependent on the cell cycle.

GCF is reported to be a transcriptional regulator that binds to specific GC-rich sequences in the epidermal growth factor (EGF) receptor gene promotor and to represses its transcription. In this study, to examine the expression of GCF in cell cycle, we have developed antibodies against GCF protein. The anti-GCF antibody recognized a major band with a molecular weight of approximately 100 kda present in human Hela cell line by immunoprecipitation followed by Western blotting. Although GCF proteins were detected throughout the cell cycle, it reached the highest level in G1 phase, and fell down to the lowest level during G2/M phase. Thus, the expression of GCF is regulated in a cell cycle-dependent manner, suggesting a potential role of GCF in the control of cell growth.

Binding Sites↗
PubMed1997

Expression of Xenopus laevis translation initiation factor 4E (eIF-4E) by baculovirus-insect cell system.

A gene encoding Xenopus laevis eIF-4E was cloned into a transfer vector, and its gene expression was attempted in cells of E. coli, yeast and insect. Effective expression of the active eIF-4E was achieved in the soluble fraction of the insect cell Sf9, which was infected with the recombinant baculovirus. Overexpression of the eIF-4E protein caused remarkable change in the shape of the cells.

Animals↗
PubMed1996

Survival factor-insensitive generation of reactive oxygen species induced by serum deprivation in neuronal cells.

To investigate the involvement of reactive oxygen species (ROS) in neuronal apoptosis, we performed confocal and flow cytometric analysis with a ROS-specific fluorogen, 6-carboxy-2', 7'-dichorodihydrofluorescein diacetate, di(acetoxymethyl ester) (C-DCDHF-DA). Serum deprivation significantly increased the level of ROS in PC12 cells and rat cortical neurons. N,N'-diphenyl-p-phenylenediamine (DPPD), an antioxidant, reduced ROS production induced by serum deprivation and recovered cell survival. However, some survival factors such as nerve growth factor and Bcl-2, which prevented the apoptosis of PC12 cells, did not affect the up-regulation of ROS induced by serum deprivation. Epidermal growth factor which prevented the apoptosis of cortical neurons, did not affect the increase of ROS. These data suggest that survival factors rescue the serum deprivation induced apoptosis independently of ROS production.

Animals↗
PubMed1996

Differential mRNA expression of phospholipase D (PLD) isozymes during cAMP-induced differentiation in C6 glioma cells.

GTP gamma S-dependent phospholipase D (PLD) activity time-dependently increased during differentiation of rat C6 glioma cells to astrocytic phenotypes induced by dibutyryl cyclic AMP (dbcAMP)/theophylline. The changes in PLD mRNA level were examined by reverse transcriptase-polymerase chain reaction (RT-PCR) method using the degenerate primers designed based on two conserved amino acid sequences in PLDs of human and yeast. The amplified three DNA fragments (tentatively termed as rPLDa, b, and c) contained the conserved regions present in PLDs of various organisms. RT-PCR using non-degenerate primers showed that rPLDa mRNA increased within 12h following treatment with dbcAMP, reaching a broad plateau and then returned to the initial level at 48h. In contrast, the level of rPLDb mRNA showed a concurrent decrease. rPLDc decreased in a time-dependent manner. These results suggest that the expression of PLD mRNAs are differentially regulated during differentiation in C6 glioma cells.

Amino Acid Sequence↗
PubMed1996

Site-directed mutagenesis of hamster complement C1S: characterization with an active form-specific antibody and possible involvement of C1S in tumorigenicity.

We have previously shown that non-transformed mouse A31 cells became tumorigenic when they were transfected with hamster C1s cDNA expression plasmid BCMGSNeoCS. In the present study, mutations were introduced into the cDNA at the activation cleavage site, Arg423(AGG) and the active center Ser617(AGC). These amino-acids were replaced by His423(CAC) and Thr617(ACC), respectively. The mutated cDNAs were inserted into BCMGSNeo and transfected to A31 and its polyoma-virus-transformed SEA7 cells. C1s produced from these transfectants lost their enzyme activity. Transfectants of these mutated C1s cDNA did not form tumors in nude mice, To distinguish between active and inactive C1s in situ, we have developed novel antibodies, one directed to the NH2-terminal neoepitope of the L chain and the other specific for uncleaved inactive C1s. These antibodies were used to characterize C1s produced by transfectants, so as to determine whether or not it was cleaved at the right position.

Amino Acid Sequence↗