Biomedical subjects

M Tsujimoto

Publications and source records attributed to M Tsujimoto.

At least 127 records · Page 7Linked to original sources

PubMed1996

SRB1, a class B scavenger receptor, recognizes both negatively charged liposomes and apoptotic cells.

Scavenger receptors mediate the recognition of a wide range of negatively charged macromolecules such as acetylated low-density lipoproteins (AcLDL). We previously reported the isolation of CHO cell variants expressing a novel type of scavenger receptor, distinct from type I and II macrophage scavenger receptors, that recognize both AcLDL and negatively charged liposomes. In the present study, we found that these isolated CHO cells express class B scavenger receptors (SRB1), which have recently been identified as a new member of the CD36 family of membrane proteins. The isolated CHO cells and CHO transfectants constitutively expressing SRB1 recognized and mediated the endocytosis of cells undergoing apoptosis as well as that of negatively charged liposomes. In contrast, CHO cells constitutively expressing type I or II scavenger receptors were unable to take up these ligands.

Animals↗

PubMed1996

Human placental leucine aminopeptidase/oxytocinase. A new member of type II membrane-spanning zinc metallopeptidase family.

The serum level of placental leucine aminopeptidase (P-LAP) increases during pregnancy. P-LAP degrades several peptide hormones such as oxytocin and vasopresin, suggesting a role in maintaining homeostasis during pregnancy. In the study reported here, we have isolated a cDNA clone with 4084 base pairs encoding P-LAP from a human placental cDNA library. The amino acid sequence deduced from the cDNA contained all of the sequences of the peptide fragments obtained by digestion of the purified protein with trypsin. The predicted P-LAP contains the HEXXH consensus sequence of zinc metallopeptidases, indicating that the enzyme belongs to this family, which includes aminopeptidase N and aminopeptidase A. The deduced sequence also contains a hydrophobic region near the N terminus, suggesting that the enzyme is a type II integral membrane protein. Northern blot analysis revealed that P-LAP was expressed in several tissues, some of which expressed two forms of mRNAs. These results suggest that the enzyme is synthesized as an integral membrane protein and is released into blood under some physiological conditions.

Amino Acid Sequence↗

PubMed1996

Oxytocin is hydrolyzed by an enzyme in human placenta that is identical to the oxytocinase of pregnancy serum.

The hydrolysis of oxytocin (OT) by human placental subcellular fractions and pregnant sera was studied in the presence of bestatin, a potent inhibitor of aminopeptidases, and the antibody against pregnant serum oxyotocinase (P-LAP)(EC 3.4 11.3) by measuring liberated amino acids by high performance liquid chromatography (HPLC). Our immunotitration study and the effect of bastatin on the oxytocin-degrading protease showed that the initiating and responsible protease in oxyotocin degradation in human placenta and pregnant serum is P-LAP.

Amino Acid Sequence↗

PubMed1996

Overexpression of p53 protein and DNA content are important biologic prognostic factors for thyroid cancer.

BACKGROUND: Many factors gave been reported to be of prognostic importance for thyroid cancer. Biologic aggressiveness may influence postoperative recurrences and the prognosis of thyroid cancer. Immunohistochemical staining for the p53 protein and DNA content are novel factors that suggest biologic aggressiveness. METHODS: Retrospective study of the survival rate after operation of differentiated thyroid cancer was undertaken at Osaka Police Hospital. Age, gender operative method, extent of lymph node dissection, use of radioiodine, primary or recurrent tumor, tumor size and invasion, lymph node involvement, presence of distant metastases, DNA ploidy, percentage of S phase and G2M phase fractions, positive staining for the p53 protein, and histologic type and subtype were evaluated as possible prognostic factors by univariate and multivariate analyses of survival. RESULTS: Positive staining for the p53 protein was related to postoperative local recurrence, and DNA ploidy was related to distant metastatic recurrence. Univariate analysis suggested that age, tumor size and invasion, lymph node involvement, presence of distant metastases, percentage of S phase fraction, histologic subtype, DNA ploidy, and positive staining for the p53 protein were significant prognostic factors. Multivariate analysis suggested that positive staining of the protein and DNA ploidy were independent prognostic factors for overall survival. CONCLUSIONS: Both positive staining for the p53 protein and DNA ploidy, which suggest biologic aggressiveness, are independent prognostic factors for overall survival of patients with thyroid cancer, Examination of these biologic factors may provide new information regarding postoperative recurrences and the prognosis of thyroid cancer.

Aged↗

PubMed1996

Expression of p21 (WAF1/CIP1) protein in clinical thyroid tissues.

p21 (WAF1/CIP1) protein expression in various thyroid tissues, including thyroid carcinoma, was studied by means of immunohistochemistry using anti-p21 monoclonal antibody. Normal follicles and hyperplasias rarely expressed p21, whereas immunohistochemically positive cells were also too rarely found in follicular adenomas to justify these cases being classified as positive. Twenty eight of the 93 carcinomas examined (30.1%), however, were positive for p21. Of the p21-positive cases, 80% of the undifferentiated and 28.6% of the poorly differentiated carcinomas showed lesions co-expressing p21 and p53. If diffuse immunoreactivity of p53 reflects the p53 mutation, our results indicate that p21 in these carcinomas can be induced by p53-independent as well as by p53-dependent pathways. On the other hand, well-differentiated carcinomas did not co-express these two proteins and it therefore remains unclear whether p53-independent or p53-dependent pathways are predominant in this type of carcinoma. The incidence of expression of p21 was very similar in undifferentiated (26.3%), poorly (28.0%) and well-differentiated carcinomas (32.7%), even though they are characterised by different degree of malignancy. Furthermore, no correlation between p21 expression and either clinical parameters or patient's prognosis could be established. These results suggest that p21 is only marginally related to the characteristics of thyroid carcinoma and can play only an adjuvant role in regulating the progression of this carcinoma.

Antibodies, Monoclonal↗

PubMed1996

[A case of the greater omentum abscess due to Peptostreptococcus ssp].

A case of the greater omentum abscess due to Peptostreptococcus ssp. is reported. A 63-year-old male was admitted to Heisei Memorial Hospital with a complaint of abdominal pain. An intraperitoneal mass measuring 6 cm in diameter was detected by CT and ultrasonogram. He was diagnosed as having an intraperitoneal abscess. After antibiotics therapy by cefotiam, laparotomy was performed and an abscess about 7 cm in diameter at the edge of the greater omentum was found. There was no evidence of perforation in the intestine wall. The abscess was removed and Peptostreptoccocus spp. was isolated from the dark red pus drained from the abscess.

Abdominal Abscess↗

PubMed1996

[A clinical features of acute respiratory infection with Haemophilus influenzae by transtracheal aspiration].

We performed a clinical study of 26 cases (27 episodes) of acute respiratory infection with H. influenzae by trans tracheal aspiration (TTA) from May 1987 to April 1995. 15 episodes (14 cases) were bronchitis and 12 episodes (12 cases) were pneumonia. 8 episodes were monomicrobial infection and 19 episodes were polymicrobial infection. Compared to the group of patients of monomicrobial infection, the number of elderly patients and the levels of WBC and CRP were higher in the group of patients of monomicroibal infection. In bronchitis cases, monomicrobial infections of H. influenzae were 7 episodes and polymicrobial infection containing H. influenzae were 8 episodes. In the latter group, PaO2 level was lower and CRP was higher on average. All patients recovered, but the period for treatment was longer in the latter group. In the pneumonia group, only one episode was monomicrobal infection and 11 episodes were polymicrobial infection. Inspite of treatment, one patient died. It was considered that polymicrobial infection was an important factor of acute respiratory infection with H. influenzae.

Acute Disease↗

PubMed1996

[A clinical study of chronic lower respiratory infection with Haemophilus influenza by transtracheal aspiration].

We have performed a clinical study on chronic lower respiratory tract infection (CLRTI) with Haemophilus influenzae (H. influenzae) by transtracheal aspiration (TTA) and analyzed clinical factors of the acute exacerbation. In 40 episodes (38 cases) of H. influenzae isolated from CLRTI, monobacterial infection with H. influenzae were 21 episodes and polymicrobial infection were 19 episodes. We classified the disease into acute exacerbated (27 episodes) and stable (13 episodes) phase and the former episodes were divided into bronchitis type (7 episodes) and pneumonia type (20 episodes). Polymicrobial infections were seen more in the pneumonia type (13 episodes) than in the bronchitis type (2 episodes). The principal organism detected with H. influenzae were alpha-Streptococcus and Neisseria sp. in the bronchitis type and S. pneumoniae in the pneumonia type. The acute exacerbated cases were divided into the following 4 patterns; 1. polymicrobial infection with continuous infection of P. aeruginosa, 2. monomicrobial infection after acute upper respiratory tract infection, 3. polymicrobial infection with S. pneumoniae after continuous infection of H. influenzae, 4. bacterial replacement by P. aeruginosa after acute exacerbation. The results of the study suggests that polymicrobial infection is an important chronic lower respiratory tract infection when caused H. influenzae.

Acute Disease↗

PubMed1996

Possible effects of placental leucine aminopeptidase on the regulation of brain-gut hormones in the fetoplacental unit.

The hydrolysis of somatostatin by human placental subcellular fractions and pregnancy sera was studied in the presence of selective inhibitors and the antibody against pregnancy serum oxytocinase (placental leucine aminopeptidase; EC3.4.11.3) by measuring the released amino acids by high-performance liquid chromatography. We also studied the degradation of other brain-gut hormones, such as glucagon, growth hormone, growth hormone releasing factor, and insulin, in the human placenta and found that the human placenta degrades somatostatin, glucagon, and growth hormone releasing factor, but not insulin and growth hormone. The degradation velocity of somatostatin was ten times greater than that of growth hormone releasing factor in placental microsomal fractions. Our data suggest that the stimulatory control by growth hormone releasing factor is dominant in the fetal growth hormone secretion. Our data also identified the somatostatin-degrading protease in human placenta using placental leucine aminopeptidase. It is known that the mean somatostatin levels in the umbilical artery are about 2.5-fold higher than those in the umbilical vein. Our data on somatostatin levels in umbilical artery and vein of intrauterine growth retardation human fetuses showed that the ratio umbilical artery/vein is around 1. Since insulin is known to be the primary hormone regulating the ratio of fetal growth, our data suggest that the degradation of somatostatin in the placenta is decreased and that elongation of somatostatin effects may result in the inhibition of insulin secretion in the intrauterine growth retardation fetus.

Amino Acid Sequence↗

PubMed1996

[Immunohistochemistry in the diagnosis and treatment of breast cancer].

Immunohistochemical staining (immunostaining) has been frequently used with breast cancer in order to give definite histological diagnosis and information for treatment or prognosis. In the histological diagnosis, immunostaining is used for differential diagnoses of tumor origin and malignancy. Immunostainings for hormone receptors and c-erbB-2 are useful for the prediction of the effect of endocrine therapy and prognosis. In the future, more important substances examined by immunohistochemistry are awaited for the diagnosis and treatment of the breast cancer.

Breast Neoplasms↗

PubMed1996

Bone morphogenetic protein-2 is markedly synergistic with tumor necrosis factor in stimulating the production of nerve growth factor in fibroblasts.

A possible interaction between tumor necrosis factor (TNF) and transforming growth factor-beta (TGF-beta) superfamily cytokines in stimulating the production of nerve growth factor (NGF) in Swiss 3T3 cells was studied. Although TGF-beta 1 and Activin A stimulated NGF production in Swiss 3T3 cells, they antagonized the stimulatory effect of TNF on fibroblast NGF production when used in combination. On the contrary, TNF's stimulatory activity on fibroblast NGF production was markedly synergized by bone morphogenetic protein-2 (BMP-2); BMP-2 by itself did not stimulate NGF production in the cells. These findings suggest that BMP-2, in concert with TNF, plays an essential role in regulating the regeneration of peripheral nerves following injury with bone fracture through an indirect mechanism by which it stimulates NGF production in fibroblasts.

3T3 Cells↗

PubMed1995

Cloning and expression of a cDNA encoding the beta-subunit (30-kDa subunit) of bovine brain platelet-activating factor acetylhydrolase.

Bovine brain platelet-activating factor (PAF) acetylhydrolase isoform Ib is a heterotrimeric enzyme. Its gamma-subunit (which, formerly, we called the 29-kDa subunit) acts as a catalytic subunit, whereas the alpha-subunit (45 kDa) is the bovine homolog of the product of human LIS-1, the causative gene of Miller-Dieker lissencephaly, indicating that this intracellular PAF acetylhydrolase plays a key role in brain development. In the current study, we cloned the cDNA for the beta-subunit (30 kDa) of bovine brain PAF acetylhydrolase Ib. The predicted 229-amino acid sequence was homologous (63.2% identity) to that of the gamma-subunit, especially (86% identity) in the catalytic and PAF receptor homologous domains. The recombinant beta-protein produced in Escherichia coli showed significant PAF acetylhydrolase activity. A mutant protein, in which Ser48, which corresponds to the active serine residue of the gamma-subunit, was replaced with cysteine showed no enzymatic activity, suggesting Ser48 is the active serine residue. Although the beta- and gamma-subunits form a heterocomplex in the native enzyme, both recombinant beta- and gamma-proteins exist as a homodimer. The purified recombinant beta-protein was labeled readily with [1,3-H]diisopropyl fluorophosphate, whereas the beta-subunit in the native complex was only labeled with higher concentrations of [1,3-3H]diisopropyl fluorophosphate to a lesser extent than the gamma-subunit. Combined with our previous data, the present study demonstrated that bovine brain PAF acetylhydrolase Ib is a unique enzyme possessing two catalytic subunits and another, possibly regulatory, subunit.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗

PubMed1995

Initiating and responsible enzyme of arginine vasopressin degradation in human placenta and pregnancy serum.

The hydrolysis of arginine vasopressin (AVP) by human placental subcellular fractions and pregnancy sera was studied in the presence of selective inhibitors and the antibody against pregnancy serum oxytocinase (P-LAP) (EC 3.4.11.3) by measuring liberated amino acids by high-performance liquid chromatography (HPLC). AVP degradation by placental subcellular fractions and pregnancy sera was inhibited by bestatin. The IC50 values of bestatin on AVP degradation by placental subcellular fractions and pregnancy sera were similar to that of this inhibitor on the P-LAP measured by L-Leu-p-nitroamnilide as a substrate (LAP activity), which we reported previously. Our immunotitration study clearly showed that the initiating and responsible protease in AVP degradation in human placenta and pregnancy serum is P-LAP. Since N-benzylcarbonyl-valyl-prolinal (Z-Val-prolinal), a selective inhibitor of post-proline endopeptidase, and phosphoramidon, a putative endopeptidase-24.11 inhibitor, could not significantly influence the degradation of AVP by placental microsomal fractions. Neither enzyme seems to be actively involved in AVP degradation.

Amino Acid Sequence↗

PubMed1995

Purification and characterization of platelet-activating factor acetylhydrolase II from bovine liver cytosol.

Platelet-activating factor (PAF) acetylhydrolase, which inactivates PAF by removing the acetyl group at the sn-2 position, is distributed widely in plasma and tissues. In a previous study, we demonstrated that the PAF acetylhydrolase activity present in the soluble fraction of bovine brain cortex could be separated chromatographically into three peaks (tentatively designated isoforms Ia, Ib, and II) (Hattori, M., Arai, H., and Inoue, K. (1993) J. Biol. Chem. 268, 18748-18753). In this study, these three isoforms were also detected in kidney and liver cytosols, although their relative activity ratios in these tissues differed. In particular, isoform II was responsible for the majority of the bovine liver PAF acetylhydrolase activity. We purified isoform II from bovine liver cytosol to near homogeneity and demonstrated that it is a single 40-kDa polypeptide. This enzyme was inactivated by diisopropyl fluorophosphate and 5,5'-dithiobis(2-nitrobenzoic acid), suggesting that both serine and cysteine residues are required for the enzyme activity, and [3H]diisopropyl fluorophosphate labeled only the 40-kDa polypeptide, confirming the enzyme's identity. Isoform II showed a comparatively broader substrate specificity than isoform Ib. Isoform II hydrolyzed propionyl and butyroyl moieties at the sn-2 position approximately half as effectively as it did PAF, whereas isoform Ib hardly hydrolyzed these substrates. Taken together with previous data, the current findings indicate that tissue cytosol contains at least two types of PAF acetylhydrolase with respect to polypeptide composition, substrate specificity, and tissue distribution and suggest that these two enzymes may share distinct physiological functions in tissues.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗

PubMed1995

cDNA cloning of human cytosolic platelet-activating factor acetylhydrolase gamma-subunit and its mRNA expression in human tissues.

The cDNA for human cytosolic platelet-activating factor acetylhydrolase (PAF-AH) gamma-subunit was isolated and the gene structure was elucidated. The complete amino acid sequence deduced from cDNA contains 231 amino acid residues. Southern blot analysis indicated the presence of a single gene. Northern blot analysis showed that 1.0 kb transcript was expressed in a tissue specific manner. Comparison of the expression pattern between adult and fetal tissues suggests that the enzyme plays an important role during the development of brain.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗

PubMed1995

Distribution and characterization of specific cellular binding proteins for bone morphogenetic protein-2.

Bone morphogenetic proteins (BMPs), which were originally identified by their novel ability to induce de novo cartilage and bone formation in vivo, are multifunctional proteins structurally related to transforming growth facto-beta s, activins, and inhibins. As a first step to elucidate the precise physiological function as well as the action mechanism of BMPs, we have examined the distribution of the specific cellular binding proteins for BMP-2 on a wide variety of cell types. A single class of high affinity-specific binding sites for BMP-2 were identified not only on osteoblastic cells but also on major types of non-hematopoietic cells in a rather ubiquitous fashion (1,200-60,000 receptors/cell, Kd = 35-230 pM); these cells included fibroblasts, keratinocytes, astrocytes, kidney epithelial cells, and tumor cells of bone, muscle, lung, liver, kidney, stomach, colon, prostate, and neuronal tissue. Other growth factors including transforming growth factor-beta 1, activin A, and inhibin A did not compete for the binding of 125I-labeled BMP-2 to the cells. Affinity cross-linking of radiolabeled BMP showed five components with apparent molecular masses of 170, 105, 90, 80, and 70 kDa common to all three fibroblast cell lines analyzed. On the other hand, no specific binding sites for BMP-2 were identified on vascular endothelial cells or on hematopoietic cells including RPMI 1788 and RPMI 8226 (B-lymphocyte lineage), MOLT-3 and MOLT-4 (T-lymphocyte lineage), HL-60 (myeloid lineage), and K-562 (erythroid lineage). These results suggest that major types of cells other than hematopoietic cells and vascular endothelial cells may be potential targets for BMP-2 action.

Animals↗

PubMed1995

Chinese hamster ovary cells expressing a novel type of acetylated low density lipoprotein receptor. Isolation and characterization.

Macrophage scavenger receptors mediate the recognition of a wide range of negatively charged macromolecules including acetylated low density lipoproteins (AcLDL). Chinese hamster ovary (CHO) cells were cultured in the presence of increasing concentrations of simvastatin, a cholesterol biosynthesis inhibitor, and AcLDL as the sole source of exogenous lipoproteins. The cells surviving under these conditions specifically bound 125I-labeled AcLDL with high affinity and degraded them via an endocytic pathway. Unexpectedly, the association and degradation of 125I-labeled AcLDL by these CHO cells were not inhibited by dextran sulfate, fucoidan, and polyinosinic acid, competitors of macrophage scavenger receptors, but were completely inhibited by maleylated bovine serum albumin. Furthermore, these cells effectively took up negatively charged liposomes containing acidic phospholipids such as phosphatidylserine and phosphatidic acid, whereas CHO cells expressing macrophage scavenger receptors did not. AcLDL and negatively charged liposomes were cross-competed with each other. Northern blot analysis using the cDNA for the macrophage scavenger receptor revealed that these CHO cells did not express this receptor. From these observations, we conclude that the isolated CHO cells express a novel type of AcLDL receptor, which is distinct from macrophage scavenger receptors with respect to ligand specificity and competitor sensitivity.

Albumins↗

PubMed1995

Serum concentrations of IL-5, GM-CSF, and IL-3 and the production by lymphocytes in various eosinophilia.

The concentrations of interleukin-5 (IL-5), granulocyte-macrophage colony-stimulating factor GM-CSF, and interleukin-3 (IL-3) in serum and in IL-2-stimulated lymphocyte culture medium (L-IL2-CM) prepared from patients with reactive eosinophilia were measured by enzyme-linked immunosorbent assay (ELISA). Serum IL-5 levels were increased in 16 out of 42 cases. GM-CSF and IL-3 were below the detectable levels in all sera examined. The concentrations of IL-5 and GM-CSF in L-IL2-CM were increased in 10 out of 29 patients. IL-3 was below the detectable levels in all L-IL2-CM.

Angioedema↗