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Biomedical subjects

H Ohta

Publications and source records attributed to H Ohta.

At least 343 records · Page 19Linked to original sources
PubMed1996

[Isoenzyme].

Expression of cancerous isoenzymes in various malignant tumors has been extensively studied using different biochemical techniques. Cancerous alkaline phosphatase (ALP) isoenzymes, such as placental ALP and variant ALP, are detected from sera of patients with various malignant diseases. Variant ALP is a specific tumor marker for hepatocellular carcinoma (HCC). The positive rate of each ALP isoenzyme is, however, low except for a high positivity of placental ALP in seminoma. Novel gamma-glutamyltranspeptidase (gamma-GTP) isoenzyme is specifically found in about 60% of the sera from patients with HCC but in only 3% of those from patients with benign liver diseases, suggesting a high specificity for HCC. Thus, cancerous isoenzymes are available for diagnosis of various malignant tumors.

Alkaline Phosphatase↗
PubMed1996

Susceptibility-weighted MR for evaluation of vasodilatory capacity with acetazolamide challenge.

PURPOSE: To investigate cerebral vasodilatory capacity by acetazolamide challenge in healthy subjects and in patients with chronic occlusive cerebrovascular disease by using susceptibility-weighted gradient-echo MR imaging. METHODS: Eight patients with chronic occlusive cerebrovascular disease and four healthy volunteers were studied with susceptibility-weighted MR imaging before and after intravenous administration of 1000 mg of acetazolamide. Signal intensities were measured as a function of time in several regions of interest defined on anatomic images. In all patients with chronic occlusive cerebrovascular disease, acetazolamide challenge and resting regional cerebral blood flow were also evaluated with single-photon emission CT (SPECT). RESULTS: In healthy volunteers, signal intensities began to increase 3 to 4 minutes after acetazolamide administration, with a continuous increase during the subsequent 10 minutes. The effect lasted for approximately 45 minutes after administration. In patients with chronic occlusive cerebrovascular disease, signal changes on susceptibility-weighted MR images of occluded areas with normal vasodilatory capacity on SPECT images did not differ from signal changes of nonocclusive areas. In those patients with changes that reflected diminished vasodilatory capacity, the MR images showed a lower percentage of signal changes after acetazolamide administration than those in normally perfused areas. CONCLUSION: Susceptibility-weighted MR imaging offers an alternative method for estimating vasodilatory capacity.

Acetazolamide↗
PubMed1996

[Long-term effect of transcatheter arterial embolization therapy for renal angiomyolipoma].

We report a case of a 21-year-old man with a right renal angiomyolipoma who has been observed for 20 months after successful treatment with selective transcatheter arterial embolization (TAE). In May 1993, he was transferred to our hospital for the treatment of an abdominal mass. Examination revealed a solid and fat-containing right renal tumor on computed tomography (CT) and magnetic resonance imaging (MRI), hypervascular staining with multiple peripheral microaneurysms on renal angiogram, indicating an angiomyolipoma (AML). He did not have any signs of tuberous sclerosis. Because he complained of abdominal pain and the tumor was 9 cm in diameter, TAE of the tumor using polyvinyl alcohol foam was performed to prevent life-threatening hemorrhage. Renal angiogram after TAE demonstrated a complete shut-down of blood supply to the tumor and CT scan, 6 and 20 months after TAE, demonstrated a decrease in size to 4.5 cm in diameter, showing a favorable long-term effect of treatment. He has been symptom-free for 20 months. TAE appears to be a safe and effective treatment for AML, preventing tumor growth and thus possibly hemorrhage or rupture of the tumor over the long -term.

Adult↗
PubMed1996

Cytotoxicity of NaCl, a stomach tumor promoter, and prevention by rice extract in stomach mucosa of F344 rats.

Cytotoxicity of NaCl and its prevention by rice extract were studied in the pyloric mucosa of male F344 rat stomach after oral administration of rice extract and 2.6 M NaCl. Effect were observed histologically by hematoxylin and eosin staining and the bromodeoxyuridine method. Replicative DNA synthesis (RDS) was assayed by liquid scintillation counter with [3H]thymidine. NaCl (2.6 M) induced destruction of the surface mucous cells within 1 min. RDS and S-phase cells increased significantly (p < 0.01) and to a maximum at 17 h, and returned to control levels 48 h after exposure. Administration of aqueous rice extract 3 h before NaCl exposure reduced the morphological damage to the mucosa and prevented the increase in RDS dose dependently by up to 65% (p < 0.01). These results showed that NaCl induced rapid mucosal damage and cell proliferation in rat stomach mucosa and that rice extract prevented the damage and reduced the increase in RDS.

Animals↗
PubMed1996

[The shock patients with the cardiac tamponade resulting from acute type A aortic dissection].

Twelve patients with acute type A aortic dissection were admitted at Ohta-Nishinouti Hospital from Jan. 1991 to Mar. 1994. Three of these 12 cases were in shock with cardiac tamponade on arrival at the hospital. Immediate resuscitative management was necessary for these patients, but pericardiocentasis was fruitless in the first case and emergent thoracotomy had led to the aortic rupture. While the second case was the thrombosed type aortic dissection and successfully performed pericardiocentasis, CT findings showed recanalization of the pseudolumen after a day, then we performed the urgent operation. By means of these experiences, the third case was operated quickly in spite of the thrombosed type aortic dissection, and had good result. We concluded that immediate surgical intervention should be taken to the shock patients with cardiac tamponade resulted from acute type A aortic dissection.

Acute Disease↗
PubMed1995

Isolation and characterization of a Photosystem II complex from the red alga Cyanidium caldarium: association of cytochrome c-550 and a 12 kDa protein with the complex.

A Photosystem II (PS II) complex was purified from an acidophilic as well as a thermophilic red alga, Cyanidium caldarium. The purified PS II complex was essentially devoid of phycobiliproteins and other contaminating components, and showed a high oxygen-evolving activity of 2375 mumol O2/mg Chl per h using phenyl-p-benzoquinone as the electron acceptor. The expression of this high activity did not require addition of exogenous Ca2+, although EDTA reduced the activity by 40%. This effect of EDTA can be reversed not only by Ca2+ but also by Mg2+; a similar Mg2+ effect has been observed in purified cyanobacterial PS II but not in higher plant PS II. Immunoblotting analysis indicated the presence of major intrinsic polypeptides commonly found in PS II from cyanobacteria and higher plants as well as the extrinsic 33 kDa protein. Antibodies against the extrinsic 23 and 17 kDa proteins of higher plant PS II, however, did not crossreact with any polypeptides in the purified PS II, indicating the absence of these proteins in the red alga. In contrast, two other extrinsic proteins of 17 and 12 kDa were present in the red algal PS II; they were released by 1 M Tris or Urea/NaCl treatment but not by 1 M NaCl. The 17 kDa polypeptide was identified to be cytochrome c-550 from heme-staining, immunoblot analysis and N-terminal amino acid sequencing, and the 12 kDa protein was found to be homologous to the 12 kDa extrinsic protein of cyanobacterial PS II from its N-terminal sequence. These results indicate that PS II from the red alga is closely related to PS II from cyanobacteria rather than to that from higher plants, and that the replacement of PS II extrinsic cytochrome c-550 and the 12 kDa protein by the extrinsic 23 and 17 kDa proteins occurred during evolution from red algae to green algae and higher plants.

Amino Acid Sequence↗
PubMed1995

Cloning, subcellular localization and expression of CHL1, a subunit of magnesium-chelatase in soybean.

Mg-insertion is the first committed step in chlorophyll synthesis and is catalyzed by Mg-chelatase. In photosynthetic bacteria, bchI gene product was suggested to be a subunit of Mg-chelatase. We isolated a bchI homolog from a soybean cDNA library and designated it as chlI. CHLI consisted of 421 amino acid residues and the sequence exhibited a high similarity to other BchI homologs. CHLI contained an ATP-binding motif found in other BchI homologs. CHLI was localized in the soluble fraction in soybean chloroplasts, suggesting that it was a stromal subunit of Mg-chelatase. chlI mRNA in cell culture (SB-P) of soybean was reversibly induced by light.

Adenosine Triphosphate↗
PubMed1995

Molecular characterization of fusion regulatory protein-1 (FRP-1) that induces multinucleated giant cell formation of monocytes and HIV gp160-mediated cell fusion. FRP-1 and 4F2/CD98 are identical molecules.

Fusion regulatory protein (FRP)-1 regulates virus-mediated cell fusion and fusion of monocytes. Eleven of fifteen N-terminal amino acids of FRP-1 were the same as the amino acid sequence of 4F2/CD98 heavy chain. FRP-1 molecules were detected in Con A- or IL-2-stimulated lymphocytes, while FRP-1 was rare on resting lymphocytes. These properties of FRP-1 are similar to those of 4F2/CD98. Treatment of monocytes with anti-4F2/CD98 mAbs resulted in cell fusion, and other mAbs directed against 4F2/CD98 induced formation of multinucleated giant cells of Cd+U2ME-7 cells, a CD4+U937 cell line transfected with the HIV gp160 gene. Both anti-4F2/CD98 and anti-FRP-1 mAbs reacted with murine L929 cells expressing human 4F2/CD98 transiently or constitutively. When Newcastle disease virus (NDV)-infected L929 cells expressing human FRP-1/CD98 were incubated with mAb 4-5-1, an anti-FRP-1 mAb, multinucleated giant cells were induced; thus, FRP-1/CD98 molecules expressed in L929 cells are functional for fusion regulatory activity.

Amino Acid Sequence↗
PubMed1995

Light-enhanced gene expression of NADPH-protochlorophyllide oxidoreductase in cucumber.

The NADPH-protochlorophyllide oxidoreductase (NPR) is a well known enzyme catalyzing photoconversion of protochlorophyllide to chlorophyllide a and its expression is negatively regulated by light. We cloned a NPR cDNA from cucumber (Cucumis sativus L.). The cDNA contained an open reading frame encoding 398 amino acids and amino acid sequence showed high similarity to those of NPR from other plants. Contrasting with most other plants, the levels of the NPR mRNA increased in etiolated cotyledons of cucumber when they were illuminated with continuous light, suggesting that the expression of this NPR gene was strongly related to chlorophyll synthesis in green leaves.

Amino Acid Sequence↗
PubMed1995

Detection of K-ras mutations in DNAs isolated from feces of patients with colorectal tumors by mutant-allele-specific amplification (MASA).

K-ras mutations are found in approximately half of all colorectal tumors examined. To explore the possibility of detecting mutated K-ras rapidly and efficiently in DNAs isolated from fecal material, we applied the mutant allele specific amplification (MASA)-PCR method to DNA from feces of patients with colorectal tumors. Among 55 colorectal adenocarcinomas or adenomas examined, 19 were found to carry K-ras mutations in codons 12 or 13. We were able to PCR-amplify DNAs isolated from feces of 15 of these 19 patients, but in only three of the fecal samples, we were able to detect the K-ras mutations corresponding to tumor DNA by MASA and ethidiumbromide staining of the gel. The carcinomas in these three cases were more than 40 mm x 40 mm in size and located in the sigmoid colon or rectum. However, we identified the K-ras mutations in fecal DNAs of additional seven patients by MASA when the gels were blotted and probed with a radio-labeled oligonucleotide; the tumors in those patients had arisen in the distal half of the colon and the smallest of these tumors was only 7 mm x 5 mm. No K-ras mutations were detectable in feces of the remaining five cases, whose tumors were relatively small and/or located in the proximal region. The results suggested that the MASA-PCR system has potential for development as a simple, rapid and noninvasive method for diagnosing the presence of colorectal tumors that carry mutant K-ras alleles, particularly tumors located in the distal colon.

Adenocarcinoma↗
PubMed1995

The influence of nutritional deficiencies on gastrointestinal uptake of cadmium and cadmium-metallothionein in rats.

The intestinal uptake and tissue distribution of cadmium (Cd) were studied in control rats and those deficient in zinc (Zn), iron (Fe) or cysteine (SH) using an in situ model where an intestinal loop of 5 cm was incubated with CdCl2 or Cd-MT (MT, metallothionein) for 30 and 60 min. The intestinal content of Cd after incubation with CdCl2 or Cd-MT was not affected by nutritional deficiencies, but the Cd uptake from CdCl2 was always higher than that from Cd-MT. However, both Fe and Zn deficiencies had a marked effect on distribution of Cd in liver, kidney and pancreas. After 30 min incubation in situ with CdCl2, Cd was deposited only in liver in control and SH deficient rats, while Cd was detected also in kidney and pancreas of both Fe and Zn deficient rats. After 60 min incubation with CdCl2, the deposition of Cd in the liver, kidney and pancreas of Fe deficient rat was significantly higher than that in the control. The deposition of Cd after Cd-MT incubation in situ was mainly found in kidney, and nutritional deficiencies increased the tissue deposition of Cd from Cd-MT. Similarly, the renal deposition of Cd absorbed from CdCl2 was markedly increased in Fe deficient rats. These results suggest that the intestinal uptake mechanisms of Cd from CdCl2 and Cd-MT are different and nutritional deficiencies can markedly increase the deposition of Cd in the kidney, the critical organ in chronic cadmium exposure.

Animals↗
PubMed1995

Induction of apoptosis by sphingosine in human leukemic HL-60 cells: a possible endogenous modulator of apoptotic DNA fragmentation occurring during phorbol ester-induced differentiation.

The present studies were undertaken to characterize the potential role of sphingosine in the regulation of apoptosis in HL-60 promyelocytic leukemia cells. A 6-h exposure of HL-60 cells to sphingosine or its methylated derivative, N,N-dimethylsphingosine, caused internucleosomal DNA fragmentation and stereotypical morphological changes characteristic of apoptosis (i.e., cell shrinkage, nuclear condensation, and the formation of apoptotic bodies), as well as that to pharmacological inhibitors of protein kinase C such as 1-(5-isoquinolinesulfonyl)-2-methylpiperazine and staurosporine. Apoptosis by sphingosine and N,N-dimethylsphingosine was measured using a flow cytometric method. The percentages of apoptotic cells in cultures treated with sphingosine (10 microM) and N,N-dimethylsphingosine (10 microM) for 6 h were 55.6 +/- 7.8% and 84.2 +/- 11.6%, respectively. HL-60 cells were induced to differentiate toward macrophages by treatment with 5 nM 4 beta-phorbol 12-myristate 13-acetate (PMA). Internucleosomal DNA fragmentation, which was a hallmark of apoptosis, was first detected after 10-h exposure to PMA and increased with longer treatment. Sphingosine concentrations in the cells increased concomitantly with the increasing proportion of apoptotic cells during cell differentiation. Sphingosine level in HL-60 cells differentiated by treatment with PMA for 48 h was about 3.3-fold greater than that in untreated cells. Differentiated HL-60 cells exhibited a markedly increased conversion of exogenously added [3H]ceramide to [3H]sphingosine, indicating elevation of ceramidase activity. Moreover, exposure to sphingosine resulted in down-regulation of c-myc mRNA. These observations suggest the possible role of sphingosine in induction of apoptotic DNA fragmentation during PMA-induced differentiation in myeloid leukemia cells. Sphingosine may function as an endogenous modulator mediating the apoptotic signal.

Apoptosis↗
PubMed1995

Chronological changes of characteristics of early gastric cancer and therapy: experience in the Cancer Institute Hospital of Tokyo, 1950-1994.

Gastric cancer, the leading cause of death from cancer in Japan, has long been studied. We received our first patient with early gastric cancer in 1950 and have since treated 2382 patients with this cancer up to 1990. The percentage of early gastric cancers diagnosed has been on the increase following the improvement in diagnostic skills and the establishment of mass screening. At present, more than half of the gastric cancers presenting are in the early stages. Chronological changes in diagnoses of early gastric cancer are characterized by the increased findings of (a) small tumors less than 4 cm in diameter (b) depressed-type carcinoma (c) lesions of the upper part of the stomach, and (d) undifferentiated-type adenocarcinoma. The standard method of treatment for early gastric cancer was standard radical operation in the 1970s. In the 1980s endoscopic mucosal resection and limited operation were adopted and their use has been increasing annually. The prognosis for early gastric cancer is quite favorable (the 5-year survival rate is more than 90%), and it is regarded as a disease with good prognosis. To obtain still better therapeutic results, it is essential to increase the proportion of early gastric cancers where endoscopic mucosal resection or limited operation is indicated, and improve the techniques of those procedures.

Endoscopy↗
PubMed1995

Rationale for extent of lymph node dissection for right colon cancer.

PURPOSE: The extent of lymph node dissection optimal for the prognosis of right colon cancer is investigated. METHODS: Between 1946 and 1991, 275 patients had curative operation for right colon cancer. A retrospective analysis of rate and degree of lymph node metastasis was performed in each of the 275 patients, and survival rate was estimated in 197 patients who could be followed over a period of three years or more. RESULTS: In most of the curative operative cases of right colon cancer, metastasis to epicolic and paracolic nodes was restricted up to 10 cm proximal or distal to the tumor margin, and metastasis in the central direction was restricted up to main nodes. When cancer metastasized to infrapyloric lymph nodes, dissection of the nodes resulted in a higher rate of long-term prognosis. The five-year cumulative survival rates showed no statistically significant difference between any two of the N0 to N3 lymph node metastasis groups. CONCLUSION: The dissection procedure for right colon cancer involved removal of 10 cm of normal bowel both proximal and distal to the lesion and, in the central direction, dissection of regional lymph nodes along the main trunk artery up to main nodes, i.e., nodes situated anterior to the surgical trunk, which was confirmed to have a therapeutically satisfactory benefit. Infrapyloric lymph nodes must be dissected when metastasis to the nodes is suspected. In cases of cecal or ascending colon cancer in which the middle colic artery is no longer the main trunk artery, a right hemicolectomy with resection of only the right branch of the middle colic artery will usually suffice.

Adult↗
PubMed1995

Ga-67 and Tc-99m (V) DMSA imaging in non-Hodgkin's lymphoma with amyloid tumor.

This report describes the localization and categorization of tumors using Ga-67 and Tc-99m (V) DMSA imaging in a rare case of non-Hodgkin's lymphoma associated with an amyloid tumor. Ga-67 uptake was found in both the lymphoma and the amyloid tumor. Significant Tc-99m (V) DMSA uptake was found only in the amyloid tumor. In this case, Ga-67 uptake was nonspecific, but Tc-99m (V) DMSA uptake gave additional information before treatment.

Adult↗
PubMed1995

Sequence analyses of human parainfluenza virus type 4A and type 4B fusion proteins.

cDNAs encoding human parainfluenza virus type 4A and type 4B (hPIV-4A and -4B) fusion (F) proteins were cloned and sequenced. The predicted amino acid sequences of the F proteins had similar characteristic traits to those reported for the F proteins of other paramyxoviruses. They were more closely related to the F proteins of simian virus 5 (SV5), mumps virus (MuV), hPIV-2 and Newcastle disease virus (NDV) than to the F proteins of hPIV-1, hPIV-3, Sendai virus (SV) and measles virus (MV). In addition, hPIV-4A, hPIV-4B, SV5 and MuV shared a common feature of genomic organization: there was a small ORF between the F and haemagglutinin-neuraminidase (HN)-coding sequences, implying a common ancestry.

Amino Acid Sequence↗