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Biomedical subjects

S Ohta

Publications and source records attributed to S Ohta.

At least 307 records · Page 17Linked to original sources
PubMed1998

[A case of bow hunter's stroke caused by bilateral vertebral artery occlusive change on head rotation to the right].

We report a case of bow hunter's stroke caused by simultaneous bilateral vertebral artery occlusive changes at the right C3-4 and the left C1-2 level on head rotation to the right side. The pathogenesis and surgical treatment for this particular case are discussed. A 61-year-old male with cervical spondylosis repeatedly experienced vertebrobasilar insufficiency when he rotated his head over 60 degree from the mid-position to the right side. Bilateral vertebral angiography demonstrated severe compression of the right vertebral artery by a lateral osteophyte and instability at the C3-4 level accompanied with the mechanical stenosis of the left vertebral artery at the C1-2 level only at the time of turning his head to the right. As the surgical treatment we performed osteophytectomy of the right uncovertebral joint at the C3-4 level in addition to anterior decompression with fusion using hydroxyapatite spacer and titanium plate at that level. Postoperatively, the patient had no ischemic episodes and there was angiographical resolution of the rotational stenosis at the C3-4 level. For the clinical manifestation of bow hunter's stroke on head rotation, it is indispensable that simultaneous severe occlusive changes present on bilateral vertebral arteries. In case of a vertebral occlusive change caused by lateral osteophyte at the unstable vertebral joint, anterior decompression and fusion with osteophytectomy may be a wiser approach than arterial decompression or posterior fusion at the C1-2 level to another vertebral artery occlusive lesion.

Cerebrovascular Disorders↗
PubMed1998

[Surgical management for preserving motor function in patients with gliomas near the primary motor cortex: usefulness of preoperative identification of motor cortex and intraoperative monitoring of motor evoked potentials].

Preoperative identification of precentral gyrus and intraoperative monitoring of motor evoked potentials (MEPs) were performed to preserve postoperative motor function in seven patients with gliomas near the primary motor cortex. Tumors were astrocytomas in 3 patients, glioblastomas in 2 patients, anaplastic astrocytoma and mixed glioma in one patient each. Preoperative identification of the primary motor cortex was performed by three-dimensional (3D) display of magnetic resonance (MR) images and by functional images using MR imaging and single-photon emission tomography. The primary motor cortex identified by 3D display of MR images coincided well with that identified by functional images. 3D display of MR images was also useful for detecting the relationship between the tumor and the primary motor cortex. Intraoperatively, the central sulcus was confirmed by the finding of phase reversal of cortical somatosensory evoked potential, and this corresponded with the preoperative identifications by 3D display and by functional mapping. The primary motor cortex was stimulated electrically, and MEP (corticospinal evoked potential) was continuously monitored during surgery using electrodes inserted in the cervical epidural space. The amplitude of direct waves of MEPs during surgery was maintained above half of that recorded at the beginning of tumor removal, and all patients showed preservation of preoperative motor function. These results suggest that preoperative identification of precentral gyrus and intraoperative MEP monitoring provide useful information for preserving motor function in patients with gliomas near the primary motor cortex.

Adult↗
PubMed1998

[Two cases of solitary peripheral pulmonary arterial aneurysm].

We report two very rare cases of solitary peripheral pulmonary arterial aneurysm. Case 1: An 83-year-old man treated for myocardial infarction died of multiple organ failure and hemoptysis. Autopsy disclosed rupture of a pulmonary arterial aneurysm 1.5 cm in diameter in the right A3. Case 2: A 75-year-old man was found to have a pulmonary arterial aneurysm, 3 cm in diameter of the right A1. Surgical treatment was not indicated, because of severe pulmonary emphysema. The aneurysms in these two cases were idiopathic: (1) there were no histologic findings that would implicate specific chronic inflammation. (2) the period from the occurrence of secondary pulmonary hypertension to hemoptysis was short, and there was no (3) history of trauma.

Aged↗
PubMed1998

[Portal hypertensive gastropathy and colopathy].

Gastrointestinal bleeding in patients with portal hypertension is usually secondary to esophageal varices, but massive bleeding from gastric mucosal lesions and colonic mucosal lesions including colorectal varices, have been variably described. These lesions are called portal hypertensive gastropathy and colopathy. The incidence and profile of portal hypertensive gastropathy (PHG) has been frequently reported during the last decade, and many studies showed that development of PHG is influenced by coexisting esophageal varices, absence of major portal systemic shunts, severity of liver disease and sclerotherapy and is directly correlated with portal venous pressure. Although hyperdynamic congestion seems to be the underlying mechanisms for the development of PHG, results of gastric mucosal blood flow in patients with PHG is controversial. The treatment can be currently recommended to prevent bleeding, is oral administration of propranolol which decreased portal venous pressure. The clinical feature and profile of portal hypertensive colopathy is classified two groups, which are named colorectal varices and colonic mucosal lesions including vascular spider, dilated fine branching vessels. Although colorectal varices are usually seen at rectum and sigmoid colon, colonic mucosal lesions are seen all part of colon. Significant relationship between colorectal varices and liver disease has been reported and colorectal varices is highly appeared in patients with extrahepatic portal obstruction. Such patients are revealed arteriovenous communications at angiogram. In general, colonic resection or transanal ligation should be the first option for treatment of bleeding colonic varices and colonic mucosal lesions. Transendoscopic sclerotherapy may be an alternate choice.

Colonic Diseases↗
PubMed1998

[Rhabdomyosarcoma of the prostate in childhood: a case report].

A case of prostatic rhabdomyosarcoma in an 8-year-old boy is presented. He was referred to Kurobe City Hospital with chief complaints of urinary retention and fever. Radiologic examinations revealed a huge prostatic tumor. Prostatic needle biopsy was performed and the pathological diagnosis was embryonal rhabdomyosarcoma of the prostate. He was referred to our hospital and treated with chemotherapy consisting of cisplatin, vincristine, cyclophosphamide, adriamycin, actinomycin-D and radiotherapy based on the regimen of IRS III. Total prostatectomy was performed 6 months after the start of therapy. Viable tumor cells were found in the prostate and the left obturator lymph nodes. After the operation, we continued chemotherapy. No recurrence was observed 8 months after the operation. However, local recurrence occurred in the pelvis 10 months after the operation and he died 2 months after the recurrence.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

Evaluation of cerebral perfusion from bypass arteries using selective intraarterial microsphere tracer after vascular reconstructive surgery.

BACKGROUND AND PURPOSE: To detect areas of cerebral perfusion from bypass arteries after vascular reconstruction, we administered selective intraarterial microsphere tracer into the external carotid arteries and determined (via single-photon emission computed tomography [IA-SPECT]) whether the distribution of radiotracer matched the arteriographic distribution of contrast material as shown on external carotid angiograms. METHODS: We compared the extent of regional distribution of tracer after external carotid artery injection of 20 to 40 MBq of 99mTc-HMPAO or 99mTc-ECD with that of contrast medium on the external carotid angiograms in 582 cortical regions in 12 patients with atherosclerotic occlusive disease and in 18 patients with moyamoya disease. RESULTS: Marked accumulation of tracer was found only in the expected, specific, newly developed areas of cerebral perfusion from bypass arteries. The regional distribution of tracer corresponded to that of contrast medium in 523 regions (90%) and did not correspond in 59 regions (10%). Significant overestimation of the distribution of contrast material relative to that of tracer was observed in the patients with moyamoya disease. CONCLUSION: SPECT showed slightly different distribution of tracer from that predicted by conventional angiography. IA-SPECT should enhance the analysis of newly developed areas of cerebral perfusion from the bypass arteries.

Adult↗
PubMed1998

Therapeutic strategy for incidentally found pituitary tumors ("pituitary incidentalomas").

OBJECTIVE: To evaluate therapeutic strategy for incidentally found pituitary tumors ("pituitary incidentalomas"), we analyzed the results of magnetic resonance imaging findings and of ophthalmological and endocrinological studies in 28 cases with long-term follow-up (Hardy's classification: Grade A, 24 cases; Grade B, 4 cases). METHODS: Only cases of nonfunctioning macroincidentaloma were analyzed in this study. Cases with ophthalmological and/or endocrinological dysfunction revealed by the first evaluation, even without subjective manifestations, were excluded from the category. Incidentally found functioning tumors were also excluded. RESULTS: The follow-up period ranged from 6 months to 10 years (mean, 5.6 yr). Magnetic resonance imaging and ophthalmological and endocrinological studies, including provocation tests, were conducted once per year. No surgical treatment was required in any case of Grade A tumors and in two cases of Grade B tumors because of no changes revealed by these studies. Transsphenoidal surgery was performed in the remaining two cases of Grade B tumors because of pituitary apoplexy. The second case was one of head injury-induced apoplexy. There were no deficits after surgery. The MIB-1 index did not differ in operated incidentaloma and symptomatic pituitary tumors. CONCLUSION: Unless ophthalmological and endocrinological dysfunction is noted, surgical treatment is not required for Grade A pituitary incidentalomas. It is not too late to remove the tumor surgically, even after some dysfunction develops. A patient having a tumor larger than Grade A can still be managed conservatively; however, the patient should be carefully informed of the possibility of pituitary apoplexy, and emergency transsphenoidal surgery is indicated if apoplexy occurs.

Adenoma↗
PubMed1997

A polypeptide derived from mitochondrial dihydrolipoamide succinyltransferase is located on the plasma membrane in skeletal muscle.

Dihydrolipoamide succinyltransferase (DLST) is the core-enzyme of 2-oxoglutarate dehydrogenase complex which is located in mitochondria. In this study, several tissues from rat and human were immunostained with an affinity-purified anti-DLST antibody. Of the tissues examined, the plasma membrane of skeletal muscle was immunostained with the antibody besides mitochondria. Furthermore, subcellular fractionation analysis coupled with Western blotting demonstrated that the antigen of the anti-DLST antibody is distributed on the plasma membrane fraction in addition to the mitochondria fraction in skeletal muscle and that it is free from the complex. The molecular weight of the polypeptide bound to the plasma membrane was about 20 kilodaltons (kDa). The polypeptide was purified by immunoprecipitation and its N-terminal amino-acid sequence was determined. The amino-acid sequence exactly corresponded to a part of DLST. Northern blots revealed the presence of mRNA corresponding to the 20 kDa protein. We are the first to report that a mitochondrial protein is also present on the plasma membrane in skeletal muscle as well as in mitochondria.

Acyltransferases↗
PubMed1997

A novel D-amino-acid-containing peptide isolated from Aplysia heart.

A novel cardio-excitatory peptide was purified from the hearts of Aplysia kurodai. The peptide was a tripeptide containing a D-amino acid residue in the second position, Asn-D-Trp-Phe-NH2 (NdWFamide). NdWFamide increased the amplitude of contractions of the perfused Aplysia heart with little effect on beating frequency, showing a threshold of approximately 10(-11) M. The peptide also potentiated spontaneous contractions of the anterior aorta. The synthetic peptide having L-Trp instead of D-Trp was about 1,000 times less potent than the native one. NdWFamide seems to play an important role in regulation of cardiac activity in Aplysia.

Animals↗
PubMed1997

Crystal structure of rat Bcl-xL. Implications for the function of the Bcl-2 protein family.

Bcl-xL is a member of the Bcl-2 protein family, which regulates apoptosis. Preparation of recombinant rat Bcl-xL yielded two forms, one deamidated at -Asn-Gly- sequences to produce isoaspartates and the other not deamidated. The crystal structures of the two forms show that they both adopt an essentially identical backbone structure which resembles the fold of human Bcl-xL: three layers of two alpha-helices each, capped at one end by two short helices. Both forms have a long disordered region, which contains the potential deamidation sites. The molecular structure exhibits a low level of interhelical interactions, the presence of three cavities, and a notable hydrophobic cleft surrounded by walls rich in basic residues. These unique structural features may be favorable for its accommodation into membranes or for possible rearrangement to modulate homo-/heterodimerization. Homology modeling of Bcl-2 and Bax, based on the Bcl-xL structure, suggests that Bax has the strongest potential for membrane insertion. Furthermore, we found a possible interface for interaction with non-Bcl-2 family member proteins, such as CED-4 homologues.

Animals↗
PubMed1997

Structure of a covalently cross-linked form of core histones present in the starfish sperm.

The post-translational modification of core histones plays an essential role in chromatin remodeling processes. We recently reported the occurrence of a novel histone modification, involving a epsilon-(gamma-glutamyl)lysine cross-link between a glutamine residue of histone H2B and a lysine residue of histone H4 in the testis of the starfish, Asterina pectinifera[Shimizu, T., Hozumi, K., Horiike, S., Nunomura, K., Ikegami, S., Takao, T., and Shimonishi, Y. (1996) Nature 380, 32]. In order to determine the complete structure of the modified histone heterodimer, p28 from both testis and sperm was purified. p28 was digested with Achromobacter lyticus protease I or Staphylococcus aureus V8 protease to give proteolytic fragments that were separated by HPLC. Amino acid analysis, sequencing, and mass spectrometric analysis of the fragments showed that the amino acid sequences of these fragments are identical to those of both histones H2B and H4, except for two NH2-terminal peptides obtained by digestion with A. lyticus protease I. One of the peptides, K8, was identical to that reported previously, and the other was a here-to-fore unidentified peptide, which was designated K10. Amino acid and positive-ion FAB-MS/MS analyses of K10 showed that it to be a fragment, derived from Gly8-Lys10 of histone H2B and Gly9-Lys16 of histone H4. The yields of K8 and K10 were calculated to be 47 and 42%, respectively, expressed as the percent of the total amount of p28 used in the experiment. Based on these data, the structure of p28 was determined to be a heterodimer, composed of histones H2B and H4, formed through a transglutaminase-catalyzed acyl transfer reaction between Gln9 of histone H2B and Lys5 or Lys12 of histone H4.

Amino Acid Sequence↗
PubMed1997

Protein synthesis inhibitor transiently reduces neuronal death in the thalamus of spontaneously hypertensive rats following cortical infarction.

Using stroke-prone spontaneously hypertensive rats with permanent occlusion of the middle cerebral artery (MCA), we investigated whether the secondary thalamic degeneration following cortical infarction is related to apoptosis, and whether the protein synthesis inhibitor cycloheximide (CHX) ameliorates this degenerative process. TdT-mediated dUTP-biotin nick end labeling (TUNEL staining) revealed a distinct pattern of nuclear staining in many ventroposterior (VP) thalamic nucleus neurons on the lesioned side at 1 week after MCA occlusion. In rats with a single or continuous intraventricular infusion of CHX, starting just after brain ischemia, in the VP thalamic neurons were significantly more numerous than those in the thalamic nucleus of rats with vehicle infusion at 1 week after MCA occlusion. However, at 2 weeks after MCA occlusion, the numbers of VP thalamic neurons were similar in the CHX- and vehicle-treated groups. These findings suggest that the secondary thalamic degeneration following cortical infarction is an event reminiscent of apoptosis and that CHX prevents the secondary thalamic neuronal death transiently.

Animals↗
PubMed1997

Bcl-2 completely blocks Fas-mediated apoptosis in mtDNA-depleted HeLa cells.

Bcl-2 inhibits apoptosis induced by a variety of death stimuli but does not completely inhibit Fas-mediated apoptosis. We have previously shown that a HeLa-derived cell line lacking mitochondrial DNA (mtDNA) expresses Fas at a high level and apoptosis is easily induced using a low concentration of an anti-Fas antibody. In this study, overexpression of Bcl-2 in the mtDNA-less cells completely blocked Fas-mediated apoptosis, and this was not due to a depression of the enhanced Fas expression. These findings suggest that the Fas-mediated apoptotic pathway is directly linked to Bcl-2 protection in the cells with an accompanying mitochondrial dysfunction.

Antibodies↗
PubMed1997

Differential display cloning of a novel rat cDNA (RNB6) that shows high expression in the neonatal brain revealed a member of Ena/VASP family.

We have used the differential display method to identify genes that control the neural cell development in CNS. Screening of the differential display bands that showed higher expression at neonate than at adult age enabled us to identify a novel rat cDNA (RNB6) coding for a protein of 393 amino acid residues. Database search revealed this gene as a rat homologue of the murine EVL, a member of Ena/VASP protein family that is implicated to be involved in the control of cell motility through actin filament assembly by their GP5 motifs. Although the precise characterization of EVL was not reported, our Northern blot and immunoblot analyses demonstrated that RNB6 expression in the brain gradually increases during embryonic development, reaches maximum at postnatal day 1 and decreases thereafter. Studies of tissue distribution revealed the expression of RNB6 not only in the brain but also in the spleen, thymus and testis. Histochemical analyses showed that RNB6 protein is mainly expressed in neurons and may be expressed in neural fibers. Our analyses suggest that RNB6 is critically involved in the development of CNS probably through the control of neural cell motility and/or including neuronal fiber extension.

Amino Acid Sequence↗
PubMed1997

Myelodysplastic syndrome and acute myelogenous leukemia as a late clonal complication in children with acquired aplastic anemia.

The improved outcome of acquired aplastic anemia (AA) has revealed later complications, such as myelodysplastic syndrome (MDS) and acute myelogenous leukemia (AML). We retrospectively analyzed 167 children with severe acquired AA. Eleven of 50 children treated with cyclosporin (CSA) and recombinant human granulocyte colony-stimulating factor (rhG-CSF) developed MDS/AML; 8 of these were within 36 months of the diagnosis of AA, much earlier than previous reports. Six of the 11 children received rhG-CSF exceeding 10 microg/kg/d, and 9 received rhG-CSF therapy for over 1 year. Ten children showed monosomy 7 at diagnosis of MDS. All of the 11 children were administered both CSA and rhG-CSF. There was no development of MDS/AML among 41 children treated with either CSA or rhG-CSF or among 48 children who underwent bone marrow transplantation. A well-controlled clinical trial is warranted to determine whether therapeutic modalities affect the development of MDS/AML in children with severe acquired AA.

Acute Disease↗
PubMed1997

Isolation of 1-methyl-1,2,3,4-tetrahydroisoquinoline-synthesizing enzyme from rat brain: a possible Parkinson's disease-preventing enzyme.

An endogenous parkinsonism-preventing substance, 1-methyl-1,2,3,4-tetrahydroisoquinoline, is enzymatically formed from 2-phenethylamine and pyruvate in rat brain. The enzyme involved was localized in the mitochondrial-synaptosomal fraction of rat brain, solubilized by treatment with sodium deoxycholate. In order to purify the enzyme, gel filtration was carried out. This enzyme may be important in the pathogenesis of Parkinson's disease.

Animals↗
PubMed1997

Mechanism of apoptotic cell death of human gastric carcinoma cells mediated by transforming growth factor beta.

Human gastric carcinoma cell line HSC-39 has been shown to undergo apoptotic cell death in response to treatment with transforming growth factor beta1 (TGF-beta1). To understand better the cell death mechanism in this TGF-beta1-mediated apoptosis, we investigated the effect of the expression of TGF-beta-stimulated clone 22 (TSC-22) on cell death events. TGF-beta1 induced TSC-22 gene expression in HSC-39 cells only when the cells had previously been adapted to the serum-free culture conditions required to undergo TGF-beta1-mediated apoptosis. HSC-39 cells transfected with a TSC-22 expression vector showed a significant decrease in cell viability compared with those transfected with a control vector. The cellular events characteristic of apoptosis, chromatin condensation and DNA fragmentation were observed only in cells transfected with a TSC-22 expression vector. On immunostaining of the transfected cells, almost every cell that expressed TSC-22 tagged with influenza virus haemagglutinin exhibited the morphology of an apoptotic cell. Partial protection from the cell death effect of TGF-beta1 on HSC-39 cells was observed when cells were treated with acetyl-L-aspartyl-L-glutamyl-L-valyl-L-aspart-1-al (Ac-DEVD-CHO, an inhibitor specific for CPP32-type protease). Protection against cell death by the transfection of a TSC-22 expression vector was also offered by Ac-DEVD-CHO addition. These results suggest that TSC-22 elicits the apoptotic cell death of human gastric carcinoma cells through the activation of CPP32-like protease and mediates the TGF-beta1 signalling pathway to apoptosis.

Apoptosis↗