Biomedical subjects

M Ohashi

Publications and source records attributed to M Ohashi.

At least 55 records · Page 3Linked to original sources

PubMed2000

Possible mechanisms underlying the vasodilatation induced by olprinone, a phosphodiesterase III inhibitor, in rabbit coronary artery.

The possible mechanisms underlying the vasodilatation induced by olprinone, a phosphodiesterase type III inhibitor, were investigated in smooth muscle of the rabbit coronary artery. Isometric force and membrane potential were measured simultaneously using endothelium-denuded smooth muscle strips. Acetylcholine (ACh, 3 microM) produced a contraction with a membrane depolarization (15. 2+/-1.1 mV). In a solution containing 5.9 mM K(+), olprinone (100 microM) hyperpolarized the resting membrane and (i) caused the absolute membrane potential level reached with ACh to be more negative (but did not reduce the delta membrane potential seen with ACh, 15.2+/-1.8 mV) and (ii) attenuated the ACh-induced contraction. In a solution containing 30 mM K(+), these effects were not seen with olprinone. Glibenclamide (10 microM) blocked the olprinone-induced membrane hyperpolarization. 4-AP (0.1 mM) significantly attenuated the olprinone-induced resting membrane hyperpolarization but TEA (1 mM) had no such effect. Glibenclamide (10 +microM), TEA (1 mM) and 4-AP (0.1 mM), given separately, all failed to modify the inhibitory actions of olprinone on (i) the absolute membrane potential level seen with ACh and (ii) the ACh-induced contraction. It is suggested that olprinone inhibits the ACh-induced contraction through an effect on the absolute level of membrane potential achieved with ACh in smooth muscle of the rabbit coronary artery. It is also suggested that glibenclamide-sensitive, ATP-sensitive K(+) channels do not play an important role in the olprinone-induced inhibition of the ACh-induced contraction.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2000

Adenovirus-mediated overexpression of Fas induces apoptosis of gliomas.

Gliomas express a higher amount of Fas than normal brain tissue. It is of interest to know whether expression of the Fas receptor is unfavorable to the antiapoptotic pathways in gliomas. In this study, we introduced the Fas gene via an adenovirus vector (Adeno-Fas) into the A-172, U251, and U-373 MG glioma cell lines, each of which expresses Fas on the cell surface. Infection of Adeno-Fas induced apoptosis in each glioma cell line. In U251 cells and A-172 cells that express the same level of Fas as a result of infection with Adeno-Fas, a much higher percentage of U251 cells underwent apoptosis than did A-172 cells. This suggests that each glioma cell line has its own threshold of Fas expression, above which apoptosis is induced, and that the constitutive expression of Fas is below the level of this threshold. It was found that the constitutive expression of the anti-apoptotic gene Bcl-X(L) is higher in A-172 cells than in U251 cells. Adenovirus-mediated transduction of the Bcl-X(L) gene into U251 cells effectively suppressed Adeno-Fas-mediated apoptosis. These data indicate that the Bcl-X(L) gene is one of the important determinants of the threshold for Fas-mediated apoptosis. When U251 and U-373 MG cells were transduced with the Fas gene controlled by the myelin basic protein promoter, which had been shown to be active in gliomas but not in neural tissues, the cells underwent markedly enhanced apoptosis. Taken together, these results indicate that the overexpression of Fas alone induced apoptosis in each glioma cell line. The degree of Fas-mediated apoptosis was attenuated by the expression of an anti-apoptotic gene, Bcl-X(L). The adenovirus-mediated induction of Fas gene controlled by a tissue-specific promoter (e.g., myelin basic protein promoter) would be a promising therapeutic approach for malignant glioma.

Adenoviridae↗

PubMed2000

The mouse SKD1, a homologue of yeast Vps4p, is required for normal endosomal trafficking and morphology in mammalian cells.

The mouse SKD1 is an AAA-type ATPase homologous to the yeast Vps4p implicated in transport from endosomes to the vacuole. To elucidate a possible role of SKD1 in mammalian endocytosis, we generated a mutant SKD1, harboring a mutation (E235Q) that is equivalent to the dominant negative mutation (E233Q) in Vps4p. Overexpression of the mutant SKD1 in cultured mammalian cells caused defect in uptake of transferrin and low-density lipoprotein. This was due to loss of their receptors from the cell surface. The decrease of the surface transferrin receptor (TfR) was correlated with expression levels of the mutant protein. The mutant protein displayed a perinuclear punctate distribution in contrast to a diffuse pattern of the wild-type SKD1. TfR, the lysosomal protein lamp-1, endocytosed dextran, and epidermal growth factor but not markers for the secretory pathway were accumulated in the mutant SKD1-localized compartments. Degradation of epidermal growth factor was inhibited. Electron microscopy revealed that the compartments were exaggerated multivesicular vacuoles with numerous tubulo-vesicular extensions containing TfR and endocytosed horseradish peroxidase. The early endosome antigen EEA1 was also redistributed to these aberrant membranes. Taken together, our findings suggest that SKD1 regulates morphology of endosomes and membrane traffic through them.

ATPases Associated with Diverse Cellular Activitie↗

PubMed2000

Unilateral hilar lymphadenopathy of sarcoidosis or sarcoid reaction compressing the trunk of the right pulmonary artery.

A case of sarcoidosis or sarcoid reaction with a rare manifestation of unilateral lymphadenopathy compressing the trunk of the right pulmonary artery is presented. A 71-year-old woman was admitted for evaluation of a left hilar mass. Chest CT scans showed a mass invading the right pulmonary artery. A frozen section obtained following open lung biopsy showed lymph node tissue largely replaced by noncaseous granulomas indicating sarcoidosis or sarcoid reaction. Old uveitis was compatible with sarcoidosis, and no malignancy was evident. These findings suggested sarcoidosis, however, other evidence of sarcoidosis was not obtained.

Aged↗

PubMed2000

Arrested maturing multivesicular endosomes observed in a Chinese hamster ovary cell mutant, LEX2, isolated by repeated flow-cytometric cell sorting.

Chinese hamster ovary (CHO) cell mutants defective in the disintegration of endocytosed low-density lipoprotein (LDL) were isolated from mutagenized cells by repeated flow-cytometric cell sorting. After seven rounds of cell sorting, we obtained mutant pools, from which nine mutant clones were established. These mutant strains were all recessive, and were categorized into three complementation groups A, B, and C. The previously established CHO mutant, LEX1 (Lysosome-Endosome X1), fell into the complementation group A. One of the newly isolated mutants, LEX2, fell into the complementation group B, and showed slower degradation of RET-LDL than LEX1 cells. LEX2 showed prominence of well-elaborated multivesicular bodies (MVBs), positive for lysosomal glycoprotein-B/cathepsin D and cation-independent mannose 6-phosphate receptor (CI-MPR), yet negative for transferrin receptor or rab7. Endocytosed intact LDL accumulated in these CI-MPR-positive structures starting at 10-15 minutes of internalization and the accumulation reached completion at 20 minutes. Intermixing of separately internalized fluorescent LDLs between the LEX2 MVBs was slow and saturable at a lower level than observed between late endosomes/lysosomes in wild-type or in LEX1 cells. The receptor recycling pathway to the plasma membrane and the acidification of intracellular compartments were normal in LEX2 cells. These results are consistent with the idea that LEX2 cells are defective in the segregation and sequestration of contents at compartments equivalent to the transport intermediates, previously referred to as endosomal carrier vesicles or maturing MVBs. This MVB stage is likely to be an earlier stage than rab7-positive, lysosome-interacting late endosomes observed in LEX1 cells. Thus, LEX1 and LEX2 mutations could be considered as landmarks for these distinct late endocytic stages, and use of these cells in biochemical and molecular genetic analyses would help to understand the as yet unidentified details of late endocytic pathways including the MVB dynamics.

Animals↗

PubMed2000

[Traumatic brain injury in childhood: introductory remarks].

Age-dependent diversity of pediatric head injury was overviewed and significance of early implementation of rehabilitation in head-injured children was emphasized. Survivors from severe traumatic brain injury (TBI) often sustains chronic physical and cognitive dysfunction. It is important for physicians and therapists to provide them with early rehabilitation treatment in a coordinated way. These children often require a long-term support from medical as well as educational specialists after finishing the hospital phase of rehabilitation.

Brain Injuries↗

PubMed2000

[Rehabilitation and outcome of the adult traumatic brain injury].

One-hundred and seventy traumatic brain injured persons were admitted to Kanagawa Rehabilitation Hospital for a rehabilitation program during a five-years period. The average age was 30.7 years and the male to female ratio was 5:1. The most common cause of injury was an traffic accident. They exhibited various physical and cognitive dysfunctions. Patients with severe physical and/or cognitive dysfunction had difficulty in community re-integration after finishing the hospital rehabilitation. At present, social resources for traumatic brain injury patients and family to fulfill their various needs are so few that they tend to be isolated from the community.

Accidents, Traffic↗

PubMed2000

A case report of surgical treatment of quadricuspid aortic valve associated with regurgitation.

A case of a 65-year-old woman who had a quadricuspid aortic valve associated with aortic regurgitation is reported. The patient had severe aortic regurgitation and four equally divided aortic cusps. The valve abnormality was detected by a transesophageal echo and an aortography. The incomplete aortic valve was excised and replaced by a St. Jude Medical prosthesis. Although this case had no coronary abnormality, a coronary displacement is often reported in quadricuspid aortic valve cases. In order to perform an operation safely, accurate information which is obtained by a non-invasive examination of the transesoph-ageal echo is quite valuable as it can indicate the need for further preoperative examinations of the coronary arteries.

Aged↗

PubMed2000

[The latest surgical treatment for gastric carcinoma, aiming both at cure and postoperative quality of life].

Based on the progress in both medical techniques and tools, in addition to the evaluation of accumulated cases, some new surgical treatments for gastric carcinoma have been attempted which aim both at cure and postoperative quality of life. Sentinel node navigation surgery, autonerve-preserving gastrectomy, laparoscopic surgery and extended surgery combined with neo-adjuvant chemotherapy are reviewed as the treatments promising further development. While it is true that many problems remain to be settled in each treatment, the advantages of these new treatments are greater than those of the standard one. A prudent attitude toward the indications and detailed study of the outcome, therefore, will be required for these treatments to become standard in the future.

Endoscopy↗

PubMed2000

[Two cases of advanced gastric cancer responding to TS-1: a novel oral formation of 5-fluorouracil].

TS-1, a novel oral formation of 5-fluorouracil, consists of 1 M tegafur (5-FU), 0.4 M CDHP and 1 M Oxo. The response rate in the late phase II study was reported as 49% in the patients with advanced gastric cancer. We report two patients with metastases from gastric cancer who markedly responded to TS-1. CASE 1: A 74-year-old man who suffered abdominal tumor was admitted to our hospital. Computed tomography (CT) showed advanced gastric cancer with huge liver metastases and extensive lymph node metastases. After 120 mg of TS-1 was orally administered for 12 weeks, CT showed a 77% reduction in the liver metastases. No serious adverse reactions were observed. CASE 2: A 66-year-old man had undergone a curative distal gastrectomy with D2 lymphadenectomy. One year later, CT showed enlargement of paraaortic lymph nodes due to cancer recurrence. There were no metastatic lesions in the other organs. After 100 mg of TS-1 was orally administered for 4 weeks, CT revealed that almost complete reduction of the metastatic nodes was obtained. Adverse reactions at grade 2 for leucopenia and anemia were observed. In conclusion, TS-1 was effective and well tolerable for patients with advanced gastric cancer.

Administration, Oral↗

PubMed2000

[Two patients with liver metastasis from gastric cancer who responded remarkably to combined therapy of 5'-DFUR and PSK].

Two patients with liver metastasis from gastric cancer who responded remarkably to a combined therapy of 5'-DFUR and PSK are reported. The first patient had liver metastases 8 months postoperatively. Her AFP level was 513 ng/ml and CEA was 30 ng/ml. After the combined therapy, all liver metastases showed a calcified change. Tumor markers of AFP and CEA decreased remarkably to the normal level within 3 weeks after the therapy. The patient had no relapse as of December 1999. The second patient with liver metastases was treated using the same combined therapy for 14 days preoperatively. The size of liver metastases had decreased remarkably by the time of the operation. A small metastasis of S8 (0.5 x 0.5 cm) was resected. No other liver metastasis was detected by intraoperative ultrasonography. The patient had no relapse as of February 2000. It is reported that PSK produces several cytokines which induce thymidine phosphorylase expression. The present report suggests that the upregulation of PyNPase might enhance the antitumor effect of 5'-DFUR.

Aged↗

PubMed1999

A retinoic acid-inducible modular protease in budding ascidians.

Retinoic acid-treated mesenchyme cells of the budding ascidian Polyandrocarpa misakiensis acquire an organizer activity to induce a secondary body axis when implanted into developing buds. We identified several different mRNAs that were upregulated in the mesenchyme cells after retinoic acid treatment. We isolated a cDNA clone corresponding to one of these mRNAs. The C-terminal region of the predicted protein product is homologous to the catalytic domain of serine proteases that belong to the trypsin family. The N-terminal region contains several types of protein-protein interaction domains. We therefore named this protein tunicate retinoic acid-inducible modular protease (TRAMP). Expression of the TRAMP mRNA in mesenchyme cells during budding and its upregulation by retinoic acid were demonstrated by reverse transcription-PCR and in situ hybridization. A glutathione S-transferase-TRAMP fusion protein showed a protease activity with trypsin-like substrate specificity and stimulated proliferation of the cell line established in this species.

Amino Acid Sequence↗

PubMed1999

Age-dependent changes in DNA polymerase fidelity and proofreading activity during cellular aging.

DNA polymerase alpha and the 3'-->5' exonuclease involved in the proofreading of DNA synthesis were isolated from human diploid fetal lung fibroblast (TIG-1) cells at various population doubling levels (PDL). The final PDL of the TIG-1 cells used in these experiments was 70. The fidelity of DNA polymerase alpha remained high until late passage and fell suddenly just before the end of the life span between 65 and 69 PDL. The activities of the 3'-->5' exonuclease related to proofreading remained unchanged from 21 to 61 PDL, but the activity decreased rapidly in more aged cells. The 3'-->5' exonuclease activity at 69 PDL was about 50% of that in TIG cells at 21 PDL. In vitro DNA synthesis by DNA polymerase alpha from TIG-1 cells harvested at 69 PDL showed the amount of non-complementary nucleotides incorporated to be decreased by the addition of the 3'-->5' exonuclease from the same cells. However, not all errors were edited out since the ratio of DNA polymerase activity to 3'-->5' exonuclease activity was adjusted to reflect that in vivo and the infidelity of DNA synthesis by error-prone DNA polymerase alpha from aged cells was improved by the addition of the highly active 3'-->5' exonuclease from cells at 41 PDL. These results suggested that the mutation frequency rises just before the end of the life span of TIG-1 cells.

Cell Line↗

PubMed1999

Inhibition of mutant p53 phosphorylation at serine 15 or serine 315 partially restores the function of wild-type p53.

The tumor suppressor protein p53 is a phosphoprotein and has growth and transformation suppression functions. Phosphorylation of wild-type p53 is known to modulate its function. To investigate the role of phosphorylation in modulating the functions of mutant p53, we constructed a series of phosphorylation site mutants based on mutant p53 Ala143 (p53-143) and p53 His175 (p53-175). When transfected into p53-negative Saos-2 cells, parental mutant p53-143 and p53-175 abolished both growth suppression and induction of apoptosis. However, DNA-activated protein kinase (DNA-PK) or cyclin-dependent kinase (cdks) phosphorylation site double mutants partially restored the growth suppression and induction of apoptosis and recovered the p53-specific DNA binding activity. We also observed a difference in sensitivity to calpain from parental mutants p53-175 and p53-175/15 or p53-175/315. These results suggest that the lack of phosphorylation at either the DNA-PK or cdks site in p53 mutants partially restores the wild-type functions by altering their conformation.

Apoptosis↗

PubMed1999

Highly augmented cytopathic effect of a fiber-mutant E1B-defective adenovirus for gene therapy of gliomas.

An E1B 55-kDa gene-defective adenovirus (Adv), ONYX-015, has been reported to be a highly useful replication-competent Adv that shows cytopathic effect for cancers with an abnormal p53 gene, without damaging normal tissues. In this study, we combined this Adv (Adv-E1AdB) with a fiber mutation, F/K20, which has a stretch of 20 lysine residues added at the COOH-terminus of the fiber and shows high transduction efficiency to gliomas. In U-373 MG glioma cells, the transduction efficiency of Adv-F/ K20 for lacZ was nine times higher than that of the Adv with wild-type fiber (Adv-F/wt) for lacZ. At a multiplicity of infection of 30, the replication efficiency of Adv-E1AdB-F/K20 was 11 times higher than that of Adv-E1AdB with wt fiber (Adv-E1AdB-F/wt). The ED50 value of AdvE1AdB-F/K20 to U-373 MG cells, which is a measure of the in vitro cytopathic effect, was 32 times greater than that of Adv-E1AdB-F/wt. injection of Adv-E1AdB-F/K20 suppressed the in vivo growth of tumors. The antitumoral effect of Adv-E1AdB-F/K20 was remarkably stronger than that of Adv-E1AdB-F/wt. A greater quantity of replicated virus protein (hexon) by infection with Adv-E1AdB-F/K20 was demonstrated in vitro and in vivo, compared with that of Adv-E1AdB-F/wt. In conclusion, gene therapy using Adv-E1AdB-F/K20, which drastically augmented the antitumoral effect of Adv-E1AdB, will be a promising therapeutic approach for gliomas.

Adenovirus E1B Proteins↗

PubMed1999

High-throughput nonradioisotopic detection of picomole levels of phosphothreonine and phosphoserine containing peptides via biotinylation and enzyme-linked immunosorbent assay.

Determination of phosphorylation sites in proteins is usually accomplished using [gamma-32P]ATP. For low-abundance phosphoproteins, in vivo and intact cell studies usually require millicurie levels of 32P for a single experiment, making multiple experiments prohibitive. Here we describe a low picomole sensitivity, nonradioisotopic, high-throughput method for tracing phosphorylation sites in proteins and peptides. The method is based on in situ enzyme-linked immunosorbent assay (ELISA) plate biotinylation of nonphospho- and phosphopeptides, streptavidin capture, and ELISA detection using recently available anti-phospho-Thr and anti-phospho-Ser antibodies.

Amino Acid Sequence↗

PubMed1999

In vitro sonographic evaluation of common bile duct stones and fragments with a high-frequency microprobe.

PURPOSE: This study was conducted to evaluate the sonographic characteristics of common bile duct (CBD) stones and stone fragments scanned in vitro with a high-frequency (20-MHz) microprobe. METHODS: We sonographically examined 4 whole CBD stones (1 cholesterol stone with radiant cross section, 1 cholesterol stone with lamellar cross section, 1 black pigment stone, and 1 brown pigment stone), 44 fragments of a cholesterol stone (diameter range, 1.1-3.0 mm; mean diameter, 2.0 mm), and 75 fragments of a black pigment stone (diameter range, 1.1-3.0 mm; mean diameter, 2.0 mm). The chemical composition of all stones was analyzed by infrared absorption spectroscopy. All stones and fragments were placed in a plastic box filled with physiologic saline solution for scanning with a 20-MHz microprobe and a 5-MHz probe. Echogenic foci and acoustic shadows revealed at each frequency were compared. RESULTS: At 5 MHz, the 4 CBD stones showed different sonographic characteristics. The cholesterol stone with radiant cross section showed an echogenic focus but no definite acoustic shadow, whereas the cholesterol stone with lamellar cross section showed an echogenic line, several echogenic spots, and a definite acoustic shadow. The black pigment stone showed an echogenic line with a vague acoustic shadow, and the brown pigment stone showed echogenicity of the whole stone and a definite acoustic shadow. At 20 MHz, the 4 stones showed an echogenic line with a definite acoustic shadow. All fragments appeared as echogenic foci at 20 and 5 MHz. Seventy-seven percent (34) and 5% (2) of 44 cholesterol stone fragments cast a definite acoustic shadow at 20 and 5 MHz, respectively. Sixty-nine percent (52) and 15% (11) of 75 black pigment stone fragments cast a definite acoustic shadow at 20 and 5 MHz, respectively. Among fragments 1.5 mm in diameter and smaller, only 45% (5 of 11) from a cholesterol stone and 30% (6 of 20) from a black pigment stone showed a definite acoustic shadow at 20 MHz. CONCLUSIONS: High-frequency (20-MHz) sonography demonstrates a definite acoustic shadow more frequently among CBD stones and fragments 1.6 mm in diameter or larger than does low-frequency (5-MHz) sonography, but it does not discriminate the chemical composition.

Adult↗

PubMed1999

Washout of small stones in the bile duct by saline infusion using a side-holed balloon catheter in patients undergoing endoscopic papillary balloon dilation.

BACKGROUND: Complete bile duct clearance of stones should be achieved in patients managed with endoscopic papillary balloon dilation. However, complete retrieval of small stones or tiny fragments sometimes proves difficult using conventional devices. METHODS: We attempted the removal of fine stone fragments by saline infusion using a specially designed retrieval balloon catheter with a blind tip and a side hole located proximal to the balloon in 14 patients. RESULTS: Using this technique, bile duct clearance was achieved in a single attempt in 13 of 14 patients; 2 attempts were required in 1 patient. Cholecystitis occurred in 2 patients with gallstones in situ after the procedure. CONCLUSIONS: Saline washout using a side-holed retrieval balloon catheter effectively cleans stones and stone fragments from the bile duct in patients treated with endoscopic papillary balloon dilation.

Aged↗