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Biomedical subjects

M Hatanaka

Publications and source records attributed to M Hatanaka.

At least 163 records · Page 9Linked to original sources
PubMed1992

Multiple forms of rat calpastatin cDNA in the coding region of functionally unknown amino-terminal domain.

Partial mouse and rat calpastatin cDNAs containing functionally unknown amino-terminal regions were cloned by the polymerase chain reaction (PCR) method. Two types of clones were obtained for the rat calpastatin; one had a sequence similar to mouse and human calpastatins, while the other had a deletion of 38 amino acid residues in this region. Both types of the rat sequence differed from the previously reported rat calpastatin which had additional deletions. The occurrence of multiple forms of calpastatin suggests alternative splicing in the functionally unknown domain.

Amino Acid Sequence↗
PubMed1992

The presence of antibodies to purified p24gag protein of HTLV-I in sera of patients with systemic lupus erythematosus (SLE).

Sera of patients with systemic lupus erythematosus (SLE) were tested for their reactivity to HTLV-I by western blotting (WB). Seven (18%) of 40 SLE serum samples reacted to the p24gag protein of HTLV-I by WB using purified gag antigens. The specificity of anti-p24gag antibodies in the SLE sera was confirmed by competitive inhibition on WB. Two of the seven patients were shown to be HTLV-I carriers, because HTLV-I infected T cell lines were easily established from their peripheral blood mononuclear cells (PBMC). Except for these two carrier patients, the gag proteins were not detected in the lysates of PBMC by WB using anti-p24gag and anti-p19gag monoclonal antibodies. The gag and pX genes of HTLV-I were not detected by PCR in PBMC of the SLE patients, with the exception of the 2 HTLV-I carrier patients. These results show no direct involvement of HTLV-I in the etiology of SLE. However, the existence of a specific antibody to p24gag in the sera of some of the noncarrier SLE patients suggests a crossreactivity to either unknown viruses or some autoantigens.

Base Sequence↗
PubMed1992

Induction of avascular yolk sac due to reduction of basic fibroblast growth factor by retinoic acid in mice.

Vasculogenesis depends on autocrine secretion of basic fibroblast growth factor (bFGF) from capillary endothelial cells. Retinoic acid (RA) induced avascular yolk sac (AVY) of mouse embryos of dams given 60 mg/kg of RA orally on Day 8 of gestation and sacrificed 3 days later. We studied the localization and transcriptional expression of bFGF and FGF-receptor (flg), heparin-binding growth factor (HBGF) activity, localization of lysosomal enzymes and alpha 1-antitrypsin (AAT), and electron microscopy of the normal mouse visceral yolk sac (VYS) and AVY. bFGF, which is normally present in the endoderm of the VYS of 8-day-old embryos and in all components of the VYS by Day 11 of gestation, was reduced in the AVY. However, in the presence of bFGF in vitro capillary nets were restored in the AVY. The mRNA for bFGF was not detectable in either VYS or AVY, while flg mRNA was detected equally in both organs in Northern blotting. The characteristic distribution pattern of lysosomal enzymes, acid phosphatase, lysozyme, and cathepsin D, and AAT was altered in the AVY. The level of acid phosphatase and AAT was reduced to 10% in the AVY. Electron microscopy revealed a partial or total loss of lysosomal membranes where the contents of lysosomes fused with adjacent lysosomes and the external organelles. These results suggest that vitelline blood vessels are not developed by endogenous autocrine bFGF but by exogenous transcellular bFGF from absorptive endodermal cells. Retinoic acid does not affect the angiogenic capacity of the VYS mesenchyme but destroys lysosomes, which release hydrolytic enzymes, leading to degradation of AAT in the endodermal cells and then digestion of endocytosed bFGF.

Acid Phosphatase↗
PubMed1992

Maturational stage specific immunoglobulin heavy chain gene rearrangements, determined by D and D upstream region gene structures.

In 43 cases of various B-cell lineage tumors, precise gene structures of rearranged immunoglobulin heavy chain (IgH) were studied. By Southern-blot analysis of D upstream (5'D) gene of IgH, biallelic rearrangement structures, D-J or V-D-J, were determined and consequently maturational stage specific IgH rearrangement patterns were investigated. B-precursor ALL cases (especially stage IV of Nadler's criteria) have V-D-J rearranged IgH genes on both alleles. In contrast, most of the mature B-cell malignancies, excluding multiple myeloma, have IgH genotype of D-J/V-D-J. In addition, in case of D-J/V-D-J, the D gene used in D-J joining has been speculated by Southern-blot of D genes. So, these approaches for inquiring precise structures of rearranged IgH genes are supposed to provide new information of lymphocyte differentiation and leukemogenesis.

Antigenic Variation↗
PubMed1992

Commitment reversion model of unrestricted cell growth.

Through the analysis of accumulated experimental data of cell growth, a model of unrestricted cell growth is presented here. This model is based hypothetically on the cellular commitment to senescence as in the previously presented commitment theory. Cells are divided into 3 types, namely uncommitted cells, committed cells and terminal cells. The division of an uncommitted cell produces an uncommitted cell itself and a committed cell of the first generation. This committed cell goes through a limited number of cell divisions until the cells become non-dividing terminal cells. It is hypothesized that during a committed cell division, there is a very small probability that an uncommitted cell may be generated. With computer simulations, it is estimated that a committed cell of the first generation may divide around 30 times until they become non-dividing terminal cells, and that the probability of an uncommitted cell regeneration for each committed cell division may be 2(-H). This hypothesis may possibly clarify some aspects of the biological phenomena of cell growth, which can not be explained by the previous commitment theory, such as the growth pattern of cultured diploid cells, cancer initiation and promotion, and cancer progression and metastasis.

Animals↗
PubMed1992

Inhibition of human immunodeficiency virus type 1 Rev function by a Rev mutant which interferes with nuclear/nucleolar localization of Rev.

A nonfunctional mutant of human immunodeficiency virus type 1 Rev was created by deleting seven amino acid residues within the nucleolar targeting signal. This mutant Rev remained in the cytoplasm in expressed cells and strongly inhibited the function of Rev by interfering with the nuclear/nucleolar localization of coexpressed Rev. These findings strongly suggest the multimerization of Rev in the cytoplasm before migration to the nucleus/nucleolus, where wild-type Rev functions as a trans-regulator.

Amino Acid Sequence↗
PubMed1992

Correlation of basic fibroblast growth factor expression levels with the degree of malignancy and vascularity in human gliomas.

Basic fibroblast growth factor (FGF) is a mitogen, a differentiation factor for neuroectoderm-derived cells, and a potent angiogenic factor. The authors have previously demonstrated that the messenger ribonucleic acid of basic FGF is expressed in more than 90% of human gliomas. In the present study, they examined the expression of basic FGF in human glioma tissues using immunohistochemical techniques with a mouse monoclonal antibody against human basic FGF. They also correlated the basic FGF level with the histological grades of malignancy assessed by the number of nucleolar organizer regions (NOR's). Basic FGF was detected in 18 of 19 gliomas, whereas it was undetectable in two normal brains. The expression level of basic FGF peptide increased proportionally with the degree of malignancy. There was also a tendency for the number of NOR's in glioma cells to increase in glioma samples with a high level of basic FGF expression. Furthermore, most of the cases with increased vascularity demonstrated on cerebral angiograms showed a relatively high level of basic FGF expression of tumor cells and a large number of NOR's in endothelial cells in tumor tissues. These results suggest that basic FGF is actually produced in most gliomas and is involved in tumorigenesis and malignant progression as an autocrine growth factor. Moreover, basic FGF may play an important role in tumor neovascularization as a paracrine angiogenic factor.

Animals↗
PubMed1992

[ATL and its virus].

A retrovirus called Human T cell leukemia virus type 1 (HTLV-1) is a causative agent of adult T cell leukemia (ATL). A cultured cell line called MT-2, produces constitutively HTLV-1. The characteristics of HTLV-1 produced from MT-2 has been extensively investigated. The molecular mechanism of ATL leukemogenesis by HTLV-1 is discussed.

Amino Acid Sequence↗
PubMed1992

[AIDS and its virus].

An etiological agent of AIDS is a human retrovirus called HIV. The genomic structure of HIV features regulatory genes in which tat and rev genes control the viral replication and affect cellular functions. Understanding their molecular mechanism may provide a clue to prevent the onset of AIDS from the viral carriers and to direct drug designing of AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Tax protein of human T-cell leukemia virus type I is required for maintenance of the transformed phenotype.

We have isolated and characterized revertants of a clonal cell line (40MRatcl-1) of human T-cell leukemia virus type I Tax-transformed Rat1 cells. The 40MRatcl-1 cells contain a single copy of tax gene, form large colonies in soft agar, elicit tumors rapidly in nude mice and revert to the normal phenotype at low frequency. From one of its subclones (B7) bearing pSV2gpt DNA as a marker gene, four morphologically reverse-transformed cell lines were isolated. They display contact inhibition at confluency, lose the ability to form colonies in soft agar, fail to form tumors in nude mice and restore the transformed phenotype similar to that of 40MRatcl-1 cells by transfection with the tax-expression plasmid. Southern blot analysis revealed that they have lost the tax gene. Our results indicate that transformation of Rat1 cells by Tax is not the consequence of secondary mutations of cellular genes and that tax functions are directly required for establishment and maintenance of the transformed phenotype.

Animals↗
PubMed1992

Successful twenty-four-hour lung preservation with donor core cooling and leukocyte depletion in an orthotopic double lung transplantation model.

Donor core cooling with cardiopulmonary bypass is a valid method of clinical lung preservation. However, organ ischemia with this method is still limited to short-term intervals. Since circulating leukocytes participate in postischemic injury through the release of oxygen-derived free radicals, we examined whether leukocyte depletion by mechanical filtration could extend ischemic tolerance of the lung during preservation and subsequent double lung transplantation. Bovine donor lungs were preserved by donor core cooling (10 degrees to 15 degrees C) with cardiopulmonary bypass. Donor lungs were removed, stored in 4 degrees C donor blood for 24 hours, and transplanted. Graft function was studied for 6 hours after transplantation. Group 1 animals (n = 6) underwent standard cardiopulmonary bypass with whole blood for donor and recipient procedures. In group 2 (n = 6), leukocyte filters were incorporated into the cardiopulmonary bypass circuit in both donor and recipient operations. In group 2 recipient animals leukocyte counts decreased to 3% of mean baseline values and remained low during the experiment. Postischemic lung function (assessed by systemic arterial oxygenation, pulmonary artery pressure, pulmonary vascular resistance, airway pressure, lung water content, and end-point histologic characteristics) was significantly better preserved in the animals with leukocyte depletion. Leukocyte depletion by mechanical filtration in both donor and recipient improves the ischemic tolerance of the lung beyond that provided by donor core cooling alone, resulting in excellent lung function after 24 hours of ischemia.

Animals↗
PubMed1992

[Basic understanding of retroviruses].

Retroviruses contain a reverse transcriptase in the virion that converts viral genomic RNA to proviral DNA. Retroviruses are divided into three groups; oncovirus, lentivirus, and spumavirus. The oncovirus group contains HTLV-1, which causes adult T-cell leukemia, encephalomyeloneuropathy, arthritis, and alveolo-bronchopathy. The lentivirus groups contains HIV, which causes acquired immunodeficiency syndrome and dementia. The genomic structures and functions of HTLV-1 and HIV have been demonstrated to explain the pathogenesis of these retroviruses.

HIV↗
PubMed1991

Expression of human T-cell leukemia virus type I protease in Escherichia coli.

Human T-cell leukemia virus type I (HTLV-I) genome is believed to encode its own protease, although the protease has not yet been detected. To identify the HTLV-I protease, an in-frame gag (3' portion)-prt region was expressed in Escherichia coli. The 14-kDa product was detected using antisera against a synthetic peptide mimicking the fragment of HTLV-I protease, although the molecular weight of the primary translational product was 27,000. A cell extract had a proteolytic activity to cleave a synthetic peptide substrate containing the cleavage site of gag p19/p24 at the correct site in vitro. Replacement of the putative active site Asp-64 with Gly abolished both in vivo processing activity and in vitro proteolytic activity. These results suggest that the 14-kDa product is the mature enzymatically active HTLV-I protease generated through posttranslational autoprocessing in E. coli.

Amino Acid Sequence↗
PubMed1991

Structure of the active 27-residue fragment of human calpastatin.

A synthetic 27-residue peptide corresponding to exon 1B of the endogenous inhibitor calpastatin contains a well-conserved region and has an ability to inhibit the cysteine endopeptidase calpain specifically. We examined the solution structure of this peptide in DMSO-d6 by two-dimensional 1H NMR spectroscopy. Although regular secondary structures such as alpha-helix and beta-sheet were not found, the region from Ile18 to Arg23 formed a well-defined structure with a type I beta-turn. This region coincided well with the highly conserved region of calpastatin. The result strongly suggests that this turn structure is essential for the inhibitory activity of calpastatin.

Amino Acid Sequence↗
PubMed1991

[Demonstration of the architecture of the tracheobronchial wall by MR imaging: an experimental study].

To study the potential of MRI to demonstrate the architecture of the tracheobronchial wall, resected tracheobronchi of rabbits were examined with MRI. As a result, epithelium and cartilage were demonstrated as relatively low intensity bands on T1- and T2-weighted images (T1WI and T2WI). The subepithelium was of intermediate-high intensity on T1WI and of markedly high intensity on T2WI and Gd-DTPA enhanced T1WI. Peritracheobronchial fat was of markedly high intensity on T1WI and of relatively low intensity on T2WI. In conclusion, MRI was found to have the potential to demonstrate the architecture of the tracheobronchial wall as 4 layers on each sequence.

Animals↗