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H Kitaura

Publications and source records attributed to H Kitaura.

30 records · Page 2Linked to original sources
PubMed1996

Identification of ligand recognition sites in heat-stable enterotoxin receptor, membrane-associated guanylyl cyclase C by site-directed mutational analysis.

Guanylyl cyclase C (STaR), a receptor protein for heat-stable enterotoxin (STa) elaborated by Escherichia coli, is associated with and spans the plasma membrane of mammalian intestinal cells. The extracellular domain functions in the binding of STa and the association of each domain to an oligomeric form. Two amino acid residues, Arg-136 and Asp-347, were identified as the residues binding to STa in the extracellular domain of pig STaR by site-directed mutagenesis and analysis of expression on 293T cells. Replacement of these residues by other amino acid residues resulted in the loss of binding of pig STaR to STa, and as a result, STa-induced guanylyl cyclase activity was eliminated. Furthermore, mutation in a region (from Asp-347 to Val-401) which is close to the transmembrane domain caused a significant reduction in both STa-binding activity and guanylyl cyclase catalytic activity. These results suggest that the region adjacent to the transmembrane domain plays an important role in facilitating a favorable conformation of STaR for STa binding.

Animals↗
PubMed1995

Differential transcription of the MPB70 genes in two major groups of Mycobacterium bovis BCG substrains.

Substrains of Mycobacterium bovis BCG (BCG) have been divided into two major groups, high and low producers, on the basis of the amount of secretion of the MPB70 protein. The antigen is produced in high concentration by BCG Tokyo, Moreau, Russia and Sweden (high-producer substrains), whereas in BCG Pasteur, Copenhagen and Tice (low-producer substrains) it is detected at 1% (w/w) or less of the concentration of BCG Tokyo. To investigate why this protein is secreted differently, the MPB70 genes of BCG Tokyo and Pasteur were cloned, sequenced and compared. The MPB70 genes in two substrains showed exactly the same sequence. Even the upstream and downstream regions of the MPB70 gene were identical. MPB70 gene expression was assessed by means of Northern hybridization analysis and reverse transcriptase polymerase chain reaction. The mRNA was clearly detected in BCG Tokyo, but a very low level in BCG Pasteur. On the basis of these results, the difference in the secretion of the MPB70 protein between BCG Tokyo and Pasteur was attributed to differential transcription efficiencies.

Amino Acid Sequence↗
PubMed1995

Characterization of the gene encoding the MPB51, one of the major secreted protein antigens of Mycobacterium bovis BCG, and identification of the secreted protein closely related to the fibronectin binding 85 complex.

The secreted protein MPB51 is one of the major proteins in the culture filtrate of Mycobacterium bovis BCG (BCG) and is a protein immunologically cross-reacting with the fibronectin binding 85 complex secreted by this bacterium. The gene encoding MPB51 (mpb51) was cloned, sequenced, and expressed in Escherichia coli. The mpb51 gene was mapped downstream of the gene for 85A component with 179 bp spaces. The mpb51 gene encoded 299 amino acids, including 33 amino acids for the signal peptide, followed by 266 amino acids for the mature protein with a molecular mass of 27807.37 Da. This is the first complete sequence of MPB51. MPB51 showed 37-43% homology to the components of 85 complex. Two-dimensional electrophoresis of culture fluids of BCG and Western blotting indicated the existence of the other novel protein(s) which strongly cross-reacted with the alpha antigen (85B) and MPB51.

Amino Acid Sequence↗
PubMed1995

An internal control for the rapid detection of mycobacteria by amplification of a segment of the gene encoding alpha antigen.

The internal control of DNA for the rapid detection of mycobacteria by PCR is described. The 1100bp fragment for internal control was produced from Streptomyces lividans DNA with the primers used for the rapid detection of mycobacteria by PCR. The amplified reaction consequently produced two products with 782bp for mycobacteria and 1100bp for the internal control extracted from all mycobacterial DNAs containing internal control so far examined. The 1100bp amplified fragment proved to be useful as an internal control with the same primer-binding sequence for the detection of mycobacteria.

Antigens, Bacterial↗
PubMed1995

[The role of some cellular components of bacterial parasites in determining the incidence of tuberculosis: studies on mycobacterial antigens, with special reference to mycobacterial immunoreactive ribosomal and secreted proteins].

Tuberculosis remains as major disease, affecting more than 20 million people. The elimination of the disease with vaccination, rapid diagnosis, and and efficient therapy is an important objective of our study. To realize the objective, the characterization of antigens is essential. We have chosen two kinds of antigens for our study, the ribosomal antigens and and an antigenic proteins secreted by mycobacteria. The biochemical and immunological characterization of ribosomal fraction was carried out. Ribosomal proteins were purified and assessed for DTH reaction. The N-terminal amino acids sequences were determined. Total structures of S19, S7 and S12 in 30S and L7/L12 in 50S subunits were elucidated. L7/L12 had 66% homology with analogue from S. griseus which showed GTPase activity in protein synthesis. This protein was secreted in culture medium and induced strong DTH. Secreted antigenic proteins are of great interest for us. Secreted antigens may be recognized rapidly by immune system and therefore may induce rapid and high level immune response. It is also expected that it may contain protective antigens, since live BCG protect disease more efficiently than heat killed BCG. We have determined and published the total structure of four proteins (MPB64, MPB70, MPB57 and alpha antigen). We attempted to utilize this antigen for the diagnosis and the design of vaccine. The structures of alpha antigens from M. avium, M. intracellulare, M. scrofulaceum, M. kansasii and BCG were determined and its potential for application to diagnosis was presented. Using the operon of M. kansasii, alpha antigen and V3 region of HIV-1 were expressed by recombinant BCG which induced CTL in mice.

Animals↗
PubMed1993

Cloning, sequencing and expression of the gene for alpha antigen from Mycobacterium intracellulare and use of PCR for the rapid identification of Mycobacterium intracellulare.

The complete nucleotide sequence of alpha antigen secreted from Mycobacterium intracellulare (ATCC13950) was determined. The gene encoded 330 amino acids including 40 amino acids for signal peptide, followed by 290 amino acids for a mature protein with molecular mass 30,645 Da. The cloned gene was expressed in Escherichia coli by using an E. coli expression vector. Based on these results, the feasibility of rapid identification of M. intracellulare by two step polymerase chain reaction (PCR) was demonstrated.

Amino Acid Sequence↗
PubMed1991

Activation of c-myc promoter by c-myc protein in serum starved cells.

The function of the c-myc protein, the product of a proto oncogene, is not clearly understood although many reports, including ours, suggest that the c-myc protein plays several roles in the regulation of transcription and DNA replication. Here we examined the effects of c-myc protein on transcription from the c-myc promoter, and by inference its role in auto-regulation, after introducing into cultured cells a c-myc expression vector and a CAT reporter gene linked to the promoter and upstream region of the human c-myc gene. To minimize the effects of the endogenous c-myc protein on the exogenously added CAT reporter gene, the transfected cells were treated under serum-free conditions. The results show that CAT expression from the myc promoter increased in a dose-dependent manner after addition of the c-myc expression vector, and that it also required the presence of a c-myc binding sequence previously identified 2 kb upstream from c-myc's first exon. Moreover, the domains of the c-myc protein important for transactivation were determined by use of various deletions mutants of c-myc cDNA. The results showed that the N-terminal portion in the c-myc protein was necessary for transactivation beside the C-terminal portion containing basic region, helix-loop-helix, and leucine zipper.

3T3 Cells↗
PubMed1988

Stimulatory action of ascorbic acid on methyl mercury-induced lipid peroxidation in rabbit kidney cortex slices.

Effects of ascorbic acid on the methylmercuric chloride (MMC)-induced lipid peroxidation and the accumulation of MMC in rabbit kidney cortical slices were studied. Ascorbic acid had a powerful stimulatory effect on the MMC-induced lipid peroxidation, while it produced only a small increase in the MMC accumulation. This results suggests that ascorbic acid increases slightly the accumulation of MMC, but that the stimulatory action of ascorbic acid on the MMC-induced lipid peroxidation cannot be explained simply by the increase in the MMC accumulation.

Animals↗
PubMed1977

A case of eosinophilic lymphfolliculosis of the skin (Kimura's disease).

Eosinophilic lymphfolliculosis of the skin (Kimura's disease) in a 31-year-old male is reported. He had two subcutaneous tumors, 10 x 9 x 3 cm and 9 x 7 x 2 cm in size, in the right retroauricular and submaxillary areas respectively. Histopathologic examination of the tumors showed marked infiltration of eosinophils, mast cells and lymphocytes, and angiomatous proliferation of blood vessels from the dermis to the skeletal muscular tissue. In subcutaneous adipose tissue, there were numerous lymphfollicles with germinal centers in which IgE deposition with reticular appearance was observed by immunofluorescent technique. Study of the peripheral blood showed marked eosinophilia and an increase of serum IgE level. These findings suggest the possibility that Type 1 allergic reaction may be involved in the histogenesis of eosinophilic lymphfolliculosis of the skin, although there is no direct evidence for the existence of antigens which react to IgE antibody in the skin lesion.

Adult↗
PubMedDate not supplied

Knowledge and attitudes of Japanese dental health care workers towards HIV-related disease.

OBJECTIVE: The present study was undertaken to investigate knowledge of AIDS and HIV infection among Japanese dental health care workers, the source of that knowledge and attitudes of dental workers towards infected patients. METHODS: The study population surveyed by means of a self-administered questionnaire consisted of 174 dental health workers at Nagasaki University Dental Hospital, including students and trainee hygienists. RESULTS: Most respondents (100% response) claimed their major source of AIDS knowledge to be derived from the media. Almost all considered their knowledge of AIDS and HIV infection to be more than moderate but still inadequate. The majority of respondents would be hesitant about performing dental treatment on HIV-positive patients. It was widely anticipated that dental patients infected with HIV would increase in the next few years and many were anxious about the increasing occupational risk of HIV infection. Only 22.4% of respondents had the same attitude towards treating HIV-positive and HIV-negative patients. Most also considered that they would be able to take care of the oral opportunistic diseases associated with HIV. Over 90.0% of respondents requested additional education about HIV, particularly information about the prevention and spread of the virus and cross-infection requirements. CONCLUSION: It is concluded that further training in the medical and psychological aspects of treating HIV-positive patients is indicated in Japan.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

TNF-alpha-mediated multiplication of human immunodeficiency virus in chronically infected monocytoid cells by mycobacterial infection.

Mycobacterial infection is a common occurrence in patients with acquired immune deficiency syndrome. Incubation of U1, a chronically HIV-1-infected human promonocytic cell line, with Mycobacterium smegmatis, M. avium, M. bovis BCG and M. tuberculosis resulted in enhancement of p24 antigen release in the supernatant, indicating that these mycobacteria could activate HIV replication from this cell line. The amount of p24 in the culture infected with M. smegmatis was higher than in cultures infected with other mycobacteria. The amounts of p24 release in cultures infected with M. avium and M. bovis BCG were intermediate. M. tuberculosis slightly stimulated HIV replication. The amount of TNF-alpha produced by U1 cells was correlated with the amount of p24 antigen release. The IL-1beta and IL-6 levels in the supernatant from cultures infected with all species were the same. The antibody to TNF-alpha inhibited p24 release induced by mycobacterial infections. The anti-IL-1beta and anti-IL-6 antibodies, however, scarcely influenced stimulation of HIV replication by mycobacterial infection. These data suggested that activation of HIV replication by mycobacteria mainly occurred by secondary release of cytokine TNF-alpha.

HIV↗