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Biomedical subjects

Atsushi Fujita

Publications and source records attributed to Atsushi Fujita.

13 recordsLinked to original sources
PubMed2006

New technique for decompressive duraplasty using expanded polytetrafluoroethylene dura substitute--technical note.

A new technique for decompressive craniectomy with duraplasty was developed for cases in which brain swelling was present at dural closure. Expanded polytetrafluoroethylene (ePTFE) membrane is placed under the dura, covering the brain surface, without the use of sutures. The dura is then loosely sutured. The procedure was used in 13 patients. No leakage of cerebrospinal fluid into the epidural space or signs of infection were observed. Sutureless insertion of an ePTFE membrane at external decompression may increase the ease of duraplasty, decrease operating time, and avoid injury to the brain resulting from suturing the dura. The technique might be especially useful in emergency cases.

Craniotomy↗
PubMed2005

Enhancement of superficial pseudohyphal growth by overexpression of the SFG1 gene in yeast Saccharomyces cerevisiae.

In response to nitrogen limitation, diploid yeast strains of Saccharomyces cerevisiae undergo a dimorphic transition to a filamentous growth form known as pseudohyphal growth. This developmental change can be classified into two distinct growing forms: invasive pseudohyphal growth and superficial pseudohyphal growth. We identified a yeast gene, SFG1, whose overexpression predominantly enhances superficial pseudohyphal growth when starved for nitrogen. Sfg1 has a sequence similarity to members of a family of transcriptional regulators of fungal development. Cells of a homozygous sfg1/sfg1 diploid strain have a serious defect in pseudohyphal growth, indicating that Sfg1 has an essential function for pseudohyphal development. Our analyses show that Sfg1 may act separately from mitogen-activated protein kinase (MAPK) pathway and cAMP-dependent protein kinase A (PKA) pathway.

Amino Acid Sequence↗
PubMed2005

Engineering of yeast Put4 permease and its application to lager yeast for efficient proline assimilation.

The Saccharomyces cerevisiae Put4 permease is significant for the transport of proline, alanine, and glycine. Put4p downregulation is counteracted by npi1 mutation that affects the cellular ubiquitination function. Here we describe mutant Put4 permeases, in which up to nine lysine residues in the cytoplasmic N-terminal domain have been replaced by arginine. The steady-state protein level of the mutant permease Put4-20p (Lys9, Lys34, Lys35, Lys60, Lys68, Lys71, Lys93, Lys105, Lys107 --> Arg) was largely higher compared to that of the wild-type Put4p, indicating that the N-terminal lysines can undergo ubiquitination and the subsequent degradation steps. Proline is the only amino acid that yeast assimilates with difficulty under standard brewing conditions. A lager yeast strain provided with Put4-20p was able to assimilate proline efficiently during beer fermentations. These results suggest possible industrial applications of the mutant Put4 permeases in improved fermentation systems for beer and other alcoholic beverages based on proline-rich fermentable sources.

Beer↗
PubMed2004

Rax1, a protein required for the establishment of the bipolar budding pattern in yeast.

In Saccharomyces cerevisiae, cell type determines two distinct spatial budding patterns. Haploid cells exhibit an axial pattern, whereas diploid cells exhibit a bipolar pattern. Axl1, a member of the insulin-degrading enzyme (IDE) family, is the key morphological determinant for the haploid axial pattern. Here we identified a novel gene, RAX1, specifically required for the bipolar budding pattern. Loss of RAX1 alters the bipolar pattern of axl1 haploids resulting in reversion to the axial pattern, and also alters the bipolar patterns of bud3 and bud4 haploids. However, bud10 rax1 haploids exhibit a random budding pattern, suggesting Bud10 acts as the key proximal landmark in axial budding. Rax1 is required for the localization of Bud8, the distal bipolar budding landmark. Interestingly, Rax1 contains a C-terminal domain possessing some similarity to insulin-related peptides. Our results suggest that Rax1 is necessary for the establishment of the bipolar budding landmark.

Amino Acid Sequence↗
PubMed2004

Simultaneous supraventricular tachycardias in both fetuses of a twin gestation.

BACKGROUND: Fetal supraventricular tachycardia confers an increased risk of cardiac failure, hydrops, and eventual intrauterine death. Although protocols for prenatal anti-arrhythmic treatment are now well established, few published reports discuss this condition in the setting of multiple pregnancies. CASE REPORT: A 20-year-old primigravida woman with a twin pregnancy presented at 31 weeks of gestation for routine obstetrical check-up which revealed simultaneous supraventricular tachycardia in both fetuses. She was treated with oral digoxin, resulting in successful cardioversion in both of the fetuses, which was maintained until they were delivered by caesarian section at 38 weeks gestation. However, several hours after birth, tachyarrhythmias recurred in each of the infants. Combined disopyramide therapy with digoxin was necessary to control their heart rates. CONCLUSION: The treatment of arrhythmia in fetuses of a multiple gestation presents unique issues, particularly when diagnosed prior to fetal lung maturity.

Administration, Oral↗
PubMed2004

Volumetric assessment of glioma removal by intraoperative high-field magnetic resonance imaging.

OBJECTIVE: To investigate the contribution of high-field intraoperative magnetic resonance imaging (iMRI) for further reduction of tumor volume in glioma surgery. METHODS: From April 2002 to June 2003, 182 neurosurgical procedures were performed with a 1.5-T magnetic resonance system. Among patients who underwent these procedures, 47 patients with gliomas (14 with World Health Organization Grade I or II glioma, and 33 with World Health Organization Grade III or IV glioma) who underwent craniotomy were investigated retrospectively. Completeness of tumor resection and volumetric analysis were assessed with intraoperative imaging data. RESULTS: Surgical procedures were influenced by iMRI in 36.2% of operations, and surgery was continued to remove residual tumor. Additional further resection significantly reduced the percentage of final tumor volume compared with first iMRI scan (6.9% +/- 10.3% versus 21.4% +/- 13.8%; P < 0.001). Percentages of final tumor volume also were significantly reduced in both low-grade (10.3% +/- 11.5% versus 25.8% +/- 16.3%; P < 0.05) and high-grade gliomas (5.4% +/- 9.9% versus 19.5% +/- 13.0%; P < 0.001). Complete resection was achieved finally in 36.2% of all patients (low-grade, 57.1%; high-grade, 27.3%). Among the 17 patients in whom complete tumor resection was achieved, 7 complete resections (41.2%) were attributable to further tumor removal after iMRI. We did not encounter unexpected events attributable to high-field iMRI, and standard neurosurgical equipment could be used safely. CONCLUSION: Despite extended resections, introduction of high-field iMRI in conjunction with functional navigation did not translate into an increased risk of postoperative deficits. The use of high-field iMRI increased radicality in glioma surgery without additional morbidity.

Adolescent↗
PubMed2004

Frameless stereotactic surgery using intraoperative high-field magnetic resonance imaging.

This study evaluated the clinical validity of frameless stereotaxy using high-field intraoperative magnetic resonance (iMR) imaging combined with an in-room neuronavigation system. A 1.5 Tesla MR scanner in conjunction with a ceiling-mounted neuronavigation system was used during 32 frameless stereotaxy procedures consisting of 19 brain biopsies and 13 catheter placements between April 2002 and mid-October 2003. Evaluation of the procedure was based on either the rate of histological diagnostic yield or the ability to accurately position the catheter in the target region. This technique allowed successful registration with a mean error of 1.2 +/- 0.8 mm and resulted in successful placement of the instrument within the target tissue. Intraoperatively, frozen section analysis showed all biopsy samples contained pathological tissue and locations of sampling points were confirmed by iMR imaging. Specific final diagnosis was made in all 19 brain biopsies. The tip of the catheter was successfully placed into the target in all 13 patients confirmed by iMR imaging. The catheter was repositioned based on iMR imaging in four of 13 patients, increasing the rate of successful placement. There were no procedure-related neurological deficits or mortality, but we encountered two cases of wound infection, one needing surgical revision. Total additional procedure time related to the induction of iMR imaging was 76.7 +/- 23.3 minutes. This initial experience of the combination of conventional frameless stereotaxy and high-field iMR imaging improved the quality of frameless stereotaxy with low morbidity and mortality, but did not translate into a significant reduction of procedure-related time.

Adolescent↗
PubMed2004

[Intracranial hypovolemic syndrome with subdural hygroma developed massive hematoma: timing of treatment and histology of dural hypertrophy].

We report a case of a 43-year-old man treated by craniotomy for chronical subdural hematoma (CSH) due to spontaneous intracranial hypovolemia. The patient complained of sudden onset severe headache. Initial CT scan showed normal brain structure, and his headache improved with bed rest in a few days. However, MR images obtained for vertigo one month later demonstrated bilateral subdural hygroma extending to the supracerebellar space and diffuse dural enhancement after gadolinium infusion. We diagnosed bilateral subdural hygroma due to spontaneous intracranial hypovolemia, and observed him conservatively. Four months after onset, he complained of severe headache again and MR images revealed enlargement of bilateral CSH with mass effect, which had heterogenous intensity on the right convexity. We evacuated hematoma on the right by craniotomy and aspirated the left side hematoma using a burr hole. His headache improved 2 weeks after the operation with strict bed rest. The follow-up MR images showed disappearance of abnormal meningeal enhancement and improvement of brain sagging.

Adult↗
PubMed2002

In vivo activation of the constitutive androstane receptor beta (CARbeta) by treatment with dehydroepiandrosterone (DHEA) or DHEA sulfate (DHEA-S).

We investigated whether dehydroepiandrosterone (DHEA) or DHEA-sulfate (S) affected the activities of nuclear receptors, with special reference to constitutive androstane receptor beta (CARbeta). Administration of DHEA or DHEA-S enhanced the DNA binding of hepatic nuclear extracts to responsive elements for the retinoic acid receptor, the retinoic acid receptor beta 2 and the peroxisome proliferator activated receptor. The bound complexes were shown to be the CARbeta-RXR heterodimer by antibody-supershift assays. The expression of a target gene of CARbeta, Cyp2b10, was increased in liver by DHEA or DHEA-S treatment, suggesting that DHEA or DHEA-S actually activated CARbeta in vivo. It was suggested that the metabolic conversion of DHEA, DHEA-S to CARbeta ligands could occur in vivo and the metabolites could regulate the expression of CARbeta target gene expression. Our results provide new insights into the in vivo relationship between DHEA/DHEA-S and CARbeta activation.

Adjuvants, Immunologic↗
PubMed2002

Subcellular localization of Axl1, the cell type-specific regulator of polarity.

Bud-site selection in yeast offers an attractive system for studying cell polarity and asymmetric division. Haploids divide in an axial pattern, whereas diploids divide in a bipolar pattern. AXL1 is expressed in haploids but not diploids, and ectopic expression of AXL1 in diploids converts their bipolar budding pattern to an axial pattern. How Axl1 acts as a switch between the bipolar and axial patterns is not understood. Here we report that Axl1 localizes to the mother-bud neck and division site remnants of haploids. Axl1 is absent from diploids. Axl1 colocalizes with Bud3, Bud4, and Bud10, components of the axial landmark structure. This localization suggests that Axl1 couples the axial landmark with downstream polarity establishment factors. Consistent with such a role, Axl1 associated biochemically with Bud4 and Bud5. Genetic evidence suggests that Axl1 works with Bud3 and Bud4 to promote the activity of the Bud10 membrane protein. Given Axl1's suggested role in morphogenesis and cell fusion during mating, we also examined its localization during this process. Axl1 redistributes independently of the axial landmark to a tight cell surface dot at the tip of each mating projection. These dots are rapidly lost as prezygotes form.

Cell Division↗
PubMed2002

Complete penetration of the optic chiasm by an unruptured aneurysm of the ophthalmic segment: case report.

BACKGROUND: It is well known that aneurysms of the ophthalmic segment sometimes elevate the optic nerve or chiasm, and in case of large or giant aneurysms, the optic apparatus can be dramatically thinned. Nonetheless, they rarely penetrate the optic pathway completely. To our knowledge, no previous reports have dealt with the complete penetration of the optic chiasm by unruptured aneurysms of the ophthalmic segment. CASE DESCRIPTION: A 70-year-old woman presented with visual dysfunction in her left eye that she had experienced for several months. Her left visual acuity had rapidly deteriorated to the level of finger counting and visual field testing demonstrated nasal hemianopsia in the left eye and upper temporal quadrant hemianopsia in the right eye. Left internal carotid angiograms and three-dimensional digital subtraction angiograms showed an aneurysm of the ophthalmic segment projecting superomedially. Intraoperative findings revealed complete penetration of the optic chiasm by the fundus of the aneurysm. The optic pathway adjacent to the dome had become remarkably thin and dark yellow. After clipping was completed, the fundus of the aneurysm was punctured to decompress the optic chiasm. Postoperatively, patient's visual acuity in the left eye gradually recovered, but the visual field deficit persisted after the operation. CONCLUSION: This rare case demonstrates the potentially aggressive behavior of unruptured aneurysms of the ophthalmic segment. Patients with unruptured aneurysms of the ophthalmic segment who present with visual symptoms should be treated with surgical clipping to decompress the optic pathway as soon as possible.

Aged↗
PubMedDate not supplied

Increased expression of integrin beta1 is a poor prognostic factor in small-cell lung cancer.

The purpose of this study was to investigate the possible association between the expression of integrin beta1 and response to chemotherapy and survival in patients with small cell lung cancer (SCLC). One-hundred and four patients with SCLC, who had received an initial course of chemotherapy between February 1989 and July 1999, were entered into the study. There were 91 males and 13 females, with a median age of 65 years (range 40-85 years). The clinical stage of the tumors was recorded as limited disease in 43 patients and extensive disease in 61. Each patient received a full-dose of combination chemotherapy. Transbroncheal biopsy specimens of tumors obtained before chemotherapy were subjected to immunostaining for integrin beta1. Twenty-nine patients could not be evaluated for integrin beta1 immunostaining, because the tissue samples had been crushed during the biopsy procedure. Fifty-three patients had tumors with < or = 25% integrin beta1-positive cells and 22 patients had tumor with > 25% integrin beta1-positive cells. Among 75 patients whose biopsy specimens were evaluable for integrin beta1, the overall response rate to chemotherapy was 87%. When the relationship between integrin beta1 expression and tumor response to chemotherapy was considered, 17 out of 22 patients with high expression of integrin beta1 and 48 out of 53 patients with low expression of integrin beta1 showed tumor response, although the resistance rate in patients with high expression of integrin beta1 was over twice that of patients with low expression of integrin beta1 (23% vs. 9%, respectively). By comparison, the overall survival of patients with high expression of integrin beta1 (n = 22) was significantly worse than that of individuals whose tumors had low expression of integrin beta1 (n = 53; log-rank test, p=0.043; Wilcoxon test, p=0.049). The association between survival and prognostic factors was examined by multivariate regression analysis; clinical stage and integrin beta1 were found to be independent factors (p = 0.018 andp = 0.041, respectively). In conclusion, the high expression of integrin beta1 in tumor cells is a poorprognostic factor in patients with SCLC.

Adult↗