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Biomedical subjects

N Ohta

Publications and source records attributed to N Ohta.

At least 127 records · Page 7Linked to original sources
PubMed1996

The fate of Mn2+ ions inside Saccharomyces cerevisiae cells seen by electron paramagnetic resonance.

The fate of Mn2+ inside Saccharomyces cerevisiae cells was monitored during import and export processes, using information from electron paramagnetic resonance (EPR) spectroscopy analysis. EPR spectra showed that when entering the cell in high number, manganese ions immediately precipitated. If recorded under conditions that favored manganese efflux, EPR spectra indicated that only osmotically free ions were exported and that bound manganese had to turn into the soluble form before being able to leave the cell.

Cell Membrane↗
PubMed1996

Antigenic analysis of Cryptomeria japonica and Chamaecyparis obtusa using anti-Cry j 1 monoclonal antibodies.

In Japan, pollen of Cryptomeria japonica and Chamaecyparis obtusa are a yearly source of distress for many people suffering seasonally from allergic rhinitis. To study common epitopes shared by the two species, two monoclonal antibodies (moAbs) were raised against Cry j 1, which is the most predominant allergen in C. japonica. One of the moAbs was found to be reactive even to the major allergen of C. obtusa, demonstrating that the moAb (J1B01) can detect an epitope shared by both species J1B01 strongly inhibited the binding of the major allergens of C. japonica and C. obtusa to IgE of patients who are sensitive to C. japonica and C. obtusa. This finding signifies the importance of the epitope recognized by J1B01.

Allergens↗
PubMed1996

Elevated levels of soluble Fc epsilon RII/CD23 and antibodies to Epstein-Barr virus in patients with Sjögren's syndrome.

To clarify how Epstein-Barr virus (EBV) infection is responsible for Sjögren's syndrome (SjS) we measured both IgG and IgM antibodies to viral capsid antigen (VCA) of EBV in the sera of normal healthy subjects and patients with SjS. Anti-VCA IgG was detectable in all controls and patients however, anti-VCA IgG titers in the sera of SjS patients were significantly higher than those of the controls (p < 0.01). No anti-VCA IgM was detected in the sera of controls whereas anti-VCA IgM was detected in the sera from 10 out of the 13 patients with SjS. This suggests that SjS might be associated with EBV. The serum levels of sCD23 (IgE-binding factor) were also measured to assess the differential state in patients with SjS. The sCD23 level of normal individuals was 211.26 +/- 12.01 micrograms/L (value is mean +/- SE), and was 443.77 +/- 71.94 micrograms/L in the 13 patients with SjS. The mean sCD23 level in the 9 patients with SjS without any complication was 360.67 +/- 35.63 micrograms/L. In the patients with SjS, sCD23 levels were significantly higher than those in the normal individuals (p < 0.01).

Antibodies, Viral↗
PubMed1996

[A case of advanced gastric cancer showing complete disappearance of cancer cells in multiple liver metastases due to low-dose PMUE therapy].

A case of gastric cancer with liver metastasis who responded well to low-dose PMUE (CDDP, MMC, UFT, etoposide) therapy is reported. A 65-year-old man underwent distal partial gastrectomy with D2 lymph node dissection under the diagnosis of type 5 gastric cancer with multiple liver metastases. Pathological findings revealed papillary adenocarcinoma in the primary lesion and metastatic lymph nodes (No. 8a). Low-dose PMUE therapy after resection of primary lesion was effective for the liver metastases. Exacerbation was suspected, so the lesions of metastases were resected again after 2 years and 11 months postoperative course. All 4 resected lesions of metastases became old fibrous tissue with hyalinization, and 2 of 4 lesions were necrotic and surrounded by fibrous connective tissue. None of these 4 lesions included viable cancer cells. The patient has now been followed with no evidence of exacerbation. It was suggested that low-dose PMUE therapy was effective for liver metastasis of gastric cancer, especially the differentiated type.

Adenocarcinoma, Papillary↗
PubMed1995

An essential single domain response regulator required for normal cell division and differentiation in Caulobacter crescentus.

Signal transduction pathways mediated by sensor histidine kinases and cognate response regulators control a variety of physiological processes in response to environmental conditions. Here we show that in Caulobacter crescentus these systems also play essential roles in the regulation of polar morphogenesis and cell division. Previous studies have implicated histidine kinase genes pleC and divJ in the regulation of these developmental events. We now report that divK encodes an essential, cell cycle-regulated homolog of the CheY/Spo0F subfamily and present evidence that this protein is a cognate response regulator of the histidine kinase PleC. The purified kinase domain of PleC, like that of DivJ, can serve as an efficient phosphodonor to DivK and as a phospho-DivK phosphatase. Based on these and earlier genetic results we propose that PleC and DivK are members of a signal transduction pathway that couples motility and stalk formation to completion of a late cell division cycle event. Gene disruption experiments and the filamentous phenotype of the conditional divK341 mutant reveal that DivK also functions in an essential signal transduction pathway required for cell division, apparently in response to another histidine kinase. We suggest that phosphotransfer mediated by these two-component signal transduction systems may represent a general mechanism regulating cell differentiation and cell division in response to successive cell cycle checkpoints.

Amino Acid Sequence↗
PubMed1995

Regulation of the Caulobacter crescentus rpoN gene and function of the purified sigma 54 in flagellar gene transcription.

The sequential transcription of flagellar (fla) genes in the Caulobacter crescentus cell cycle is controlled by the organization of these genes in a regulatory hierarchy of four levels (I-IV). Level III and level IV genes at the bottom of the hierarchy are dependent on level II genes and are transcribed late in the cell cycle from sigma 54-dependent promoters. To study the regulation of genes at levels III and IV, we have isolated and sequenced the rpoN gene in order to analyze its expression, purified the rpoN gene product, and examined the role of the RpoN protein in initiation of transcription from sigma 54-dependent promoters. We report here epistasis experiments that show rpoN is required for transcription of level III genes, but that the expression of the rpoN gene itself is not dependent on any of the fla genes examined; these results place rpoN at level II near the top of the hierarchy. Consistent with this conclusion were nuclease S1 assays that mapped the rpoN transcription start site and identified a sequence centered at -24, GTTA/TACCA/TT, which is similar to the core consensus sequence of the level IIB fliF, fliL, and fliQ promoters. We purified the full-length rpoN gene product to near homogeneity and demonstrated that the RpoN protein is required for transcription from the well-characterized sigma 54-dependent glnAp2 promoter of Escherichia coli and specifically recognizes the level III flbG gene promoter of C. crescentus. These last results confirm that rpoN encodes the C. crescentus sigma 54 factor and opens the way for the biochemical analysis of transcriptional regulation of level III and IV fla genes.

Amino Acid Sequence↗
PubMed1995

Experimental model of chronic tonsillar herniation associated with early stage syringomyelia.

This report describes an experimental model of chronic tonsillar herniation and its effects on the spinal cord. In ten rats, a small piece of chemically induced mammary cancer was transplanted to the supraoccipital bone. In all cases, the transplanted cancers grew into the posterior fossa, destroying the supraoccipital bone and compressing the cerebellum extradurally. In six of the ten rats, tonsillar herniation was observed at 8-14 weeks after transplantation. Transdural infiltration of the tumor cells was not apparent in any animal. In those rats with tonsillar herniation (n = 6), the spinal cord from the C5 to the T8 segments showed enlargement of the central canal without exception. Histological examination revealed the following changes: stretching and thinning of the ependymal cells; swelling of the astrocytic processes; and extra-cellular edema, predominantly in the dorsal gray matter, but also in the ventral inner portion of the dorsal column. In the control group (n = 4) and those rats without tonsillar herniation (n = 4), such histological changes of the spinal cord were not observed. Although the lesions can not be regarded as representing mature syringomyelia, they most likely constitute an earlier evolutionary stage.

Animals↗
PubMed1995

Anaplastic thyroid carcinoma producing the granulocyte colony stimulating factor (G-CSF): report of a case.

We report herein the unusual case of a 60-year-old woman with an anaplastic thyroid carcinoma which produced granulocyte colony stimulating factor (G-CSF). She presented with large neck masses, respiratory difficulty, and a high fever. Laboratory examinations revealed marked leukocytosis of 43,200/mm3 with 85% granulocytes and an elevated G-CSF level of 67 pg/dl. Total thyroidectomy with bilateral node dissection and tracheostomy was performed, and a histological diagnosis of large-cell anaplastic thyroid carcinoma was confirmed. Immunohistochemical examination with a polyclonal antibody against G-CSF stained the tumor cells. Although the respiratory difficulty, fever, and marked granulocytosis subsequently improved, she died 1 month after undergoing surgery due to metastatic mediastinal disease.

Carcinoma↗
PubMed1995

[Adrenalectomy for nonfunctioning adrenal tumors--comparison between open and laparoscopic surgery, and indication for operation].

Since 1977, we have operated on 18 nonfunctioning adrenal tumors. The pathological diagnosis included seven adrenocortical adenomas, three adrenocortical hypeplasias, three ganglioneuromas two adrenal cysts, two myelolipomas and one metastatic cancer. We successfully performed laparoscopic adrenalectomy in 11 of these patients and open surgery in the other 7 patients. In the patients undergoing laparoscopic adrenalectomy, post-operative recovery (fist oral intake, first ambulation, and total convalescence) was remarkably rapid. The indication of adrenalectomy for nonfunctioning adrenal tumors is controversial, but we can not exclude the possibility of malignancy even in small tumors. Therefore, because of the minimally invasive nature of laparoscopic surgery, the indications for operating on nonfunctioning adrenal tumors will be widened by introducing laparoscopic adrenalectomy.

Adrenal Gland Neoplasms↗
PubMed1994

The Caulobacter crescentus FlbD protein acts at ftr sequence elements both to activate and to repress transcription of cell cycle-regulated flagellar genes.

The flagellar genes (fla genes) in Caulobacter crescentus are organized into a regulatory hierarchy of four levels, I-IV, in which transcription of the class III and class IV genes late in the cell cycle from sigma 54-dependent promoters depends on expression of the class II genes above them. Timing of fla gene expression has been attributed to sequential activation and repression by specific transcription factors. Here we report that purified FlbD activates transcription in vitro from the sigma 54-dependent class III flbG promoter and repress transcription from the class II fliF promoter by binding to ftr (flagellar transcription regulator) sequence elements required for their transcriptional regulation in vivo. The FlbD protein makes symmetrical base-specific contacts at three highly conserved guanine nucleotides in each half site of ftr1 and ftr1* at flbG and the single ftr4 site at fliF. The dual function of FlbD in activation of class III genes and repression of the class II fliF promoter is consistent with a central role of FlbD as a switch protein mediating the transition from level II to level III fla gene expression.

Bacterial Proteins↗
PubMed1994

Parasite infection and cancer: with special emphasis on Schistosoma japonicum infections (Trematoda). A review.

This article contains a review of current knowledge on the association of parasite infections and cancer formation, especially that of Schistosoma japonicum (Trematoda) in man and experimental animals. The association of S. haematobium infection and bladder cancer is well known and documented. However, S. japonicum infection has also been reported to be associated with cancer, in this case hepatocellular carcinoma and/or colorectal cancer. Pathological records and analyses have shown a correlation between this infection and cancer, and pathohistological descriptions have been numerous, together with clinical case reports. Epidemiological analyses have been conducted in China and Japan and support a role of S. japonicum infection as one of the risk factors in cancer formation, along with others, such as hepatitis virus infection and alcoholic intake. Experimental results have also shown that cancer appears early and in larger numbers in experimentally infected animals given a known carcinogen. In spite of these positive end-point associations, the mechanism of schistosome-mediated enhancement of carcinogenesis is obscure. A suggestive observation is that in S. japonicum-infected mice carcinogen-metabolizing hepatic activity including P-450 was decreased so that an administered carcinogen persisted for a longer period than in uninfected mice. Further studies, both epidemiological and experimental, are needed to firmly establish the relationship between schistosome infection and cancer.

Animals↗
PubMed1994

Stimulation of calf thymus DNA polymerase alpha activity by nucleolar protein B23.

Protein B23 is a major RNA-associated nucleolar protein and putative ribosome assembly factor which exists in at least two isoforms designated B23.1 and B23.2. Recently, it has been reported that B23 is copurified with DNA polymerase alpha-primase complex. To examine its possible role in DNA replication, the effects of B23 on DNA polymerase activities were investigated. B23.1 purified from rat Novikoff hepatoma ascites cell nucleoli stimulated the activity of DNA polymerase alpha by as much as 3-to 4-fold in a dose-dependent manner, while it showed little effect on the activities of DNA polymerase beta, gamma, and primase. Rat recombinant B23.1 showed the same stimulation as that of B23.1 from Novikoff cells. In contrast, isoform B23.2 showed no effect on the activity of DNA polymerase alpha, suggesting that C-terminal region of B23.1 is important in its activity in the stimulation of DNA polymerase alpha.

Animals↗