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Biomedical subjects

M Oishi

Publications and source records attributed to M Oishi.

At least 19 recordsLinked to original sources
PubMed1997

Enrichment of oligo(dG).oligo(dC)-containing fragments from human genomic DNA by Mg 2+-dependent triplex affinity capture.

Oligo(dG).oligo(dC)- or short poly(dG).poly(dC)-containing fragments were enriched and cloned by means of Mg2+-dependent triplex affinity capture and subsequent cloning procedures. A library constructed after three cycles of enrichment showed that approximately 80% of the clones in the supercoiled form formed a complex with labeled oligonucleotide (dG)34. However, while the rest of the clones retained the ability to form a complex (type I clones), 90.9% failed to form a complex when they were linearized. This group of DNA was abundant in the genomic DNA, although it showed only approximately 3-fold enrichment by one cycle of affinity capture. This group was further classified into two species (types II and III) based on complex formation ability after phenol extraction. Type II clones retained the complex formation ability after treatment, while the human telomere [(TTAGGG)n] and telomere-like [(TGGAA)n] or [(TGGAG)n] sequences belonging to type III clones did not. Serial deletion experiments and the binding assays using oligonucleotides confirmed that the repetitive units containing T(G)nT ( n = 3-5) tracts or (G)n-motifs (n >/= 3) were the sites of complex formation for type II and III clones. On the other hand, type I clones contained poly(dG).poly(dC) tracts at least 10 nt long, and DNase I-footprinting analysis indicated that these tracts were the sites of complex formation.

Cloning, Molecular↗
PubMed1997

Phosphorylation of Alzheimer beta-amyloid precursor-like proteins.

Amyloid precursor-like proteins (APLPs), APLP1 and APLP2, are members of a gene family which include the Alzheimer beta-amyloid precursor protein (APP). APLP1, APLP2, and APP contain highly homologous amino acid sequences, especially in their cytoplasmic domains, although APLPs lack the beta-amyloid domain derived by proteolytic processing from APP. APP is phosphorylated at three sites in the cytoplasmic domain in cultured cells and adult rat brain [Suzuki et al. (1994) EMBO J. 13, 1114-1122; Oishi, et al. (1997) Mol. Med. 3, 109-121] and at sites in the extracellular domain in cultured cells [Knops et al. (1993) Biochem. Biophys. Res. Commun. 197, 380-385; Hung & Selkoe (1994) EMBO J. 13, 534-542; Walter et al. (1997) J. Biol. Chem. 272, 1896-1903]. We report here that a cytoplasmic domain peptide from APLP1 is phosphorylated in vitro by protein kinase C and that a cytoplasmic domain peptide from APLP2 is phosphorylated in vitro by protein kinase C and cdc2 kinase. APLP2 is phosphorylated by cdc2 kinase at a site homologous to the cdc2 kinase site phosphorylated in APP. Furthermore, phosphorylation of this site occurs in a cell cycle-dependent manner in cultured cells. These findings indicate that in intact cells the phosphorylation of APLP2 appears to be regulated in a similar fashion to that of APP.

Alzheimer Disease↗
PubMed1997

Cerebral blood flow and cerebrovascular response to acetazolamide in patients with chronic alcoholism.

Cerebral blood flow and cerebrovascular response to acetazolamide were studied in 12 patients with chronic alcoholism and 12 age matched healthy controls. Blood flows in the cerebral cortex, thalamus, and putamen were significantly lower in the chronic alcoholic group than in the healthy control group. The increase in blood flow caused by acetazolamide did not show any significant difference between the two groups. These findings suggest that the decreased cerebral blood flow in chronic alcoholism is due to decreased cerebral metabolism.

Acetazolamide↗
PubMed1997

Cerebral blood flow in single and multiple lacunar infarctions.

BACKGROUND AND PURPOSE: Single and multiple lacunar infarctions may have some difference in underlying diseases and cerebral blood flows. To determine the difference, we investigated underlying diseases and cerebral blood flows in single and multiple lacunar infarctions. METHODS: Fifteen cases of lacunar infarction, 10 cases of multiple lacunar infarctions, and 16 control subjects were studied. Regional cerebral blood flow was measured within 14 days after stroke onset with the stable xenon CT method. RESULTS: The rate of association of diabetes mellitus was higher in the multiple lacunar infarctions group than in the single lacunar infarction group. The blood flow in the cerebral cortex was significantly lower in the multiple lacunar infarctions group than in the single lacunar infarction group. The blood flow change by acetazolamide in the cerebral cortex was significantly lower in the multiple lacunar infarctions group than in the single lacunar infarction group. CONCLUSIONS: There is some difference in underlying diseases and cerebral blood flows between single and multiple lacunar infarctions.

Acetazolamide↗
PubMed1997

Japanese experience with micropremies weighing less than 600 grams born between 1984 to 1993.

The viability limit defined by the Japanese Eugenic Protection Act was amended from 24 to 22 completed weeks of gestation in 1991. To testify if the amendment is appropriate, we conducted a survey on the mortality and morbidity rates of infants less than 600 g born in Japan between 1984 to 1993. Questionnaires were mailed to 205 hospitals with neonatal intensive care units (NICUs) and 165 (80%) responded. Of 1655 infants <600 g birth weight and admitted to the NICUs included in this survey, 457 (28%) survived to hospital discharge. The survival rates of infants born <24 weeks and >==24 weeks of gestation were 17% (128/748) and 36% (329/903), respectively; and of infants <500 g and 500 to 599 g at birth were 16% (82/510) and 32% (375/1145), respectively. None of the infants <==20 weeks of gestational age and <==350 g at birth survived, but 4% (2/49), 12% (27/218), 21% (99/474), and 34% (131/381) born at 21, 22, 23, and 24 weeks of gestation survived, respectively. The majority (68%) died within 1 week after birth and only 10% died after the neonatal period. The main causes of death were: acute respiratory failure (33%), intraventricular hemorrhage (20%), infection (16%), and heart failure (10%). Of 457 survivors, 65% were free from handicaps. The incidence of mental retardation (DQ < 70), visual disturbance, and CP were 15%, 14%, and 11%, respectively. Admission of micropremies to NICU increased markedly after the amendment of the Eugenic Protection Act, despite a marked decline in birth rate. The survival rate increased from 22% to 33% after generalized use of surfactant in 1988, but the handicap rate (35%) among survivors remained unchanged. The new viability limit of 22 complete weeks of gestation was feasible, since survival of less than 22 weeks was exceptional while survival of 22 to 23 weeks was 18%.

Cause of Death↗
PubMed1997

Failing hollow implants examined by light microscopy and image processing.

The purpose of this study was to evaluate the radiologic, histologic, and histometric findings of three failing hollow implants. On periapical radiographs, these implants showed vertical bone loss up to the hollow portion around the implant. Examination of the histologic sections disclosed that the hollow portions of all the implants were almost filled with bone tissue, although slight bone resorption and presence of granulation tissue infiltrated with inflammatory cells was observed coronal to the hollow portion. Histometric analysis disclosed that the average percent bone contact was 93.1% in case 1, 90.9% in case 2, and 84.3% in case 3 and the average percent bone filling was 42.1%, 50.5%, and 33.8%, respectively. Consequently, there seems to be some potential for successful treatment of these implants because the destructive changes were limited to the coronal aspects of the implant.

Alveolar Bone Loss↗
PubMed1997

Abscess formation around a hydroxyapatite-coated implant placed into the extraction socket with autogenous bone graft. A histological study using light microscopy, image processing, and confocal laser scanning microscopy.

The purpose of this study was to evaluate the radiologic, histologic, and histometric findings for a retrieved hydroxyapatite (HA)-coated implant which had been placed into a fresh extraction socket with autogenous bone graft 3 months previously. A periapical radiography disclosed a vertical bone loss around the implant cervix. Examination of histologic section disclosed that granulation tissue including bone chips around the cervix, and newly-formed bone tissue around the grafted bone tissue on the HA coated surface. In the confocal laser scanning microscopic findings toluidine blue-negative bone tissue showed autofluorescence. Histometric analysis indicated that the average percent bone contact was 29.2% (ranged 26.4% to 34.1%). Suspected reasons for failure were an early exposure of the barrier membrane, its early removal, the implant placement into an infected site, inadequate antibiotic premedication, and/or poor control of infections around teeth prior to implant surgery and around implants before and after placement of barrier membrane.

Abscess↗
PubMed1997

A candidate case for lymphocytic infundibulo-neurohypophysitis mimicking a neurohypophysial tumor.

A 56-year-old Japanese man presented with a 2-month duration of polyuria and polydipsia. The diagnosis of diabetes insipidus was confirmed by water deprivation and vasopressin injection. The secretory function of the adenohypophysis was estimated as normal by a variety of provocative tests. Magnetic resonance imaging (MRI) displayed the loss of the hyperintense signal of the neurohypophysis and a tumor-like lesion confined to the neurohypophysis. The tissue specimen resected at transsphenoidal surgery showed diffuse lymphocytic infiltration. These findings suggest that this is a candidate case for lymphocytic infundibuloneurohypophysitis (LIN) that is not identical to classical lymphocytic hypophysitis. This patient will be followed up to determine whether this case simply represents an early stage of classical hypophysitis or a different clinical entity.

Diabetes Insipidus↗
PubMed1997

The cytoplasmic domain of Alzheimer's amyloid precursor protein is phosphorylated at Thr654, Ser655, and Thr668 in adult rat brain and cultured cells.

BACKGROUND: The cytoplasmic domain of the Alzheimer's disease amyloid precursor protein (APP) is phosphorylated in vitro at Thr654 and Ser655, and both in vitro and in intact cells at Thr668 (numbering for APP695 isoform). MATERIALS AND METHODS: We have developed phosphorylation state-specific antibodies to each of the sites, and we have used these to analyze the phosphorylation of APP in adult rat brain and in cultured cell lines. RESULTS: We demonstrate that all three sites in APP are phosphorylated in adult rat brain. Phosphorylation at Thr654, Ser655, and Thr668 was also observed in several cultured cell lines. In PC12 cells, phosphorylation at Ser655 was increased more than 10-fold by treatment with okadaic acid, a specific inhibitor of protein phosphatases 1 and 2A, but was not affected by activators of protein kinase C. In HeLa cells, phosphorylation at Thr668 was regulated in a cell cycle-dependent manner with near-stoichiometric phosphorylation being observed at the G2/M phase of the cell cycle. In general, phosphorylation at Ser655 was found to be highest in mature APP isoforms, whereas phosphorylation of Thr668 was highest in immature APP isoforms in cultured cells. CONCLUSIONS: The results demonstrate that phosphorylation of the cytoplasmic domain of APP occurs at Thr654, Ser655, and Thr668 under physiological conditions. The further characterization of APP phosphorylation using phosphorylation-specific antibodies may help in the elucidation of the biological function of APP.

Alzheimer Disease↗
PubMed1996

Expression of the protein tyrosine phosphatase beta2 gene in mouse erythroleukemia cells induces terminal erythroid differentiation.

We have cloned cDNA for protein tyrosine phosphatase beta2, which had been implicated in erythroid differentiation of mouse erythroleukemia cells. Expression of cDNA constructs, in which beta2 cDNA is placed under the control of mouse metallothionein-I promoter, by ZnCl2 converted a significant portion (20 to 38%) of the cells to erythroid-like cells, which is 25-50% of the erythroid differentiation efficiency observed by conventional erythroid-inducing agents. Furthermore, introduction and expression of altered protein tyrosine phosphatase beta2 cDNA constructs designed to produce the enzyme lacking the phosphatase activity inhibited erythroid differentiation by 100-20%, depending upon the concentration of erythroid-inducing agents employed. These results strongly suggest that protein tyrosine phosphatase beta2 is involved in triggering erythroid differentiation in mouse erythroleukemia cells.

5-Aminolevulinate Synthetase↗
PubMed1996

In vitro transcription of a poly(dA) x poly(dT)-containing sequence is inhibited by interaction between the template and its transcripts.

Transcription of poly(dA) x poly(dT)-containing sequences was investigated in vitro using plasmids carrying a (dA)34 x (dT)34 tract in the coding region of the lacZ gene. The efficiency of transcription of the (dT)34 sequence on the transcribing strand by Escherichia coli RNA polymerase was substantially lower (approximately 60%) than that of the (dA)34 sequence or of the control lacZ gene. Analysis of the transcription process of the (dT)34 sequence by T3 RNA polymerase showed that the transcription was frequently arrested or terminated at the middle as well as immediately proximal of the (dA)34 x (dT)34 tract, and it occurred more prominently following accumulation of transcription products. This inhibition was strongly enhanced by the addition of the oligonucleotide (dT)34 or poly(U) to the reaction mixture, while (dA)34 and the duplex (dA)34 x (dT)34 suppressed the inhibition. A similar transcriptional inhibition was also observed in transcription mediated by T7 RNA polymerase and eukaryotic RNA polymerase II. We also demonstrated RNA x DNA complex formation of the (dA)34 x (dT)34 tract with poly(U), but not with poly(A). These findings strongly suggest that poly(dT)-containing template sequences interact and form a complex with its transcription products, possibly an RNA x DNA triplex, which blocks further transcription. This would explain the instability of the plasmids transcribing mRNAs with poly(U) but not poly(A) tracts and the underrepresentation of poly(U) but not poly(A) tracts in mRNAs.

DNA↗
PubMed1996

N-Shc: a neural-specific adapter molecule that mediates signaling from neurotrophin/Trk to Ras/MAPK pathway.

Shc has been implicated in a variety of growth factor- and cytokine receptor-signaling through its specific binding to phosphotyrosine residues of the activated receptors. In neuronal cells, such as PC12, Shc has been shown to be involved in Ras-dependent MAP kinase activation following Trk receptor stimulation with NGF. While the ubiquitous role of Shc as an adaptor molecule in signal transduction is increasing in both neuronal and non-neuronal cells and tissues, the expression level of Shc is surprisingly low in the brain. We demonstrated here the isolation of a neural-specific member of the Shc family. This novel protein, named N-Shc (neuronal Shc), contains two potential phosphotyrosine-binding domains, PTB and SH2, and is expressed exclusively in the brain; whereas Shc is present in all other non-neuronal tissues. As in Shc, N-Shc can bind activated EGF receptor, become tyrosine phosphorylated, and form a complex with Grb2 adapter protein following EGF stimulation. Furthermore, N-Shc can bind activated TrkB receptor following the stimulation with brain-derived neurotrophic factor (BDNF), which is the most abundant neurotrophin in the brain. These data suggest that N-Shc, rather than Shc, mediates neurotrophin and other neuronal signalings in the central nervous system.

3T3 Cells↗
PubMed1996

Construction of highly extensive polymorphic DNA libraries by in-gel competitive reassociation procedure.

Differential genomic DNA libraries between two mouse strains and from two human individuals were constructed by means of the in-gel competitive reassociation (IGCR) procedure, a procedure developed for cloning altered anonymous restriction fragments. The libraries were highly enriched in RFLP fragments, approximately 60 and 40% for the mouse and human libraries, respectively, and, more importantly, maintained most of the original complexities of the RFLP fragments. Therefore, differential genomic DNA libraries constructed by the IGCR procedure, particularly for human genomic DNA, should offer highly extensive sources for polymorphic DNA sequences necessary for a variety of genome analyses, including studies on the origin and mechanism of biological diversity among the same species.

Animals↗
PubMed1996

Beneficial effects of prostaglandin E1 on hemodynamic changes during liver transplantation in pigs.

The vasodilative action of prostaglandin E1 (PGE1) on the systemic and pulmonary circulation was investigated in swine models of orthotopic liver transplantation. In the PGE1-treated group (n = 8), PGE1 (0.05 microgram/kg per minute) was intravenously infused from the onset of the anhepatic stage to 30 min after revascularization. During the anhepatic stage, PGE1 decreased systemic vascular resistance without a corresponding hypotension, so cardiac output was maintained at a higher level. In the control group (n = 8), pulmonary vascular resistance increased to 3 times the anhepatic value during reperfusion, accompanied by a decline in cardiac output with a 28% decrease in blood pressure. In the PGE1-treated group, on the other hand, pulmonary vascular resistance was maintained within the normal range without any associated decrease in cardiac output. The blood pressure decreased slightly by 12%. In conclusion, in this model, PGE1 increased cardiac output without hypotension during the anhepatic stage and also prevented postreperfusion pulmonary hypertension and the subsequent systemic hypotension.

Alprostadil↗
PubMed1996

Central motor conduction time in patients with periventricular lucencies.

Central motor conduction time and regional cerebral blood flow were measured before and 20 min after intravenous injection of 17 mg/kg acetazolamide in 10 patients with periventricular lucencies (PVL) and 10 age-matched healthy controls. Central motor conduction time was measured using a magnetic stimulator and regional cerebral blood flow was measured by stable xenon computed tomography method. The central motor conduction time was significantly longer in the patients with PVL than in the healthy controls and was shortened significantly by the intravenous injection of acetazolamide in the patients with PVL. The blood flow not only in the periventricular white matter but also in the cerebral cortex and the cerebral white matter was significantly lower in the patients with PVL than in the healthy controls. The intravenous injection of acetazolamide increased significantly the regional cerebral blood flow except in the PVL areas. The prolongation of the central motor conduction time may be at least partly related with decreased blood flow in the cerebral cortex and cerebral white matter.

Acetazolamide↗
PubMed1996

Histologic investigation of hollow implants retrieved for psychological reasons.

OBJECTIVE: The purpose of this study was to radiologically, histologically, and histometrically evaluate bone in the hollow portion of three implants retrieved for psychological reasons. STUDY DESIGN: Three hollow implants retrieved from two patients were studied. We investigated the radiologic and histologic changes of these implants with the use of radiographs, light microscopy, image processing, and fluorescent microscopy. RESULTS: There were no radiologic and histologic degeneration around the implants. Histometric analysis of the hollow indicated that the average percentage of bone contact rate was 33.5% in case 1, 74.5% in case 2, and 18.4% in case 3; the average percentage of bone filling was 25.1%, 33.9%, and 6.6%, respectively. There was a great variation among the three cases in bone to implant contact and bone filling. CONCLUSION: The hollow portion in case 1 that penetrated into the maxillary sinus was encapsulated with fibrous tissue. The amount of bone tissue in the hollow portion seems to depend on the initial bone quality of the recipient sites.

Adaptation, Psychological↗