[Structure and function of phosphatidylserine-specific phospholipase A1: PS-PLA1].
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Amino Acid Sequence↗
Biomedical subjects
J Aoki
Publications and source records attributed to J Aoki.
[High-dose chemotherapy with autologous peripheral blood stem cell transplantation support in a patient with breast cancer metastasis to bone marrow: immunocytochemical monitoring of cancer-cell contamination].
A 32-year-old woman who 1 year earlier underwent a right mastectomy for stage II breast cancer with the histology of invasive ductal carcinoma (scirrhus type) was admitted due to recurrent, metastatic breast cancer in January 1997. She presented multiple metastatic lesions in the skin, lymph nodes, bone, lungs, liver, and spleen, and her bone marrow was replaced almost entirely by tumor cells. The patient was sequentially treated with 5 courses of cyclophosphamide (CPA) and adriamycin (ADM) (CA); 2 courses of CPA, ADM, and 5-fluorouracil; 5 caurses of docetaxel hydrate; and 1 course of CA. After recovery of the normal bone marrow by standard-dose chemotherapies, peripheral blood stem cells (PBSC) were then collected after mobilization with G-CSF. The number of breast cancer cells in bone marrow and PBSC samples was determined by immunocytochemical staining with an anti-cytokeratin monoclonal antibody. The number of tumor cells in PBSC sample was within the level for non-metastatic breast cancer. Complete remission was obtained with high-dose chemotherapy consisting of CPA and Thio-TEPA, and supported by autologous PBSC transplantation.
Adult↗
Association between polymorphisms in the type 1 sigma receptor gene and schizophrenia.
Several antipsychotic agents such as haloperidol and rimcazole are known to bind to sigma receptors with high affinity, and evidence for a potential link between sigma receptors and the etiology of schizophrenia has been reported. The present study was conducted to systematically search for nucleotide variants of the type 1 sigma receptor gene in 48 schizophrenics. Two polymorphisms were found: GC-241-240TT in the 5' flanking region and Gln2Pro. These two polymorphisms were in nearly complete linkage disequilibrium with each other. The Pro2 variant of the Gln2Pro polymorphism changes the endoplasmic reticulum retention signal motif. These polymorphisms were examined in an extended sample of schizophrenics (n = 308) and controls (n = 433) and a significant association between the presence of the TT/Pro2 haplotype and schizophrenia was observed (odds ratio = 1.27, P = 0.04).
Adolescent↗
Localization of alpha-tocopherol transfer protein in rat brain.
Vitamin E (alpha-tocopherol) is a fat-soluble antioxidant that is transported by plasma lipoproteins in the body. Alpha-tocopherol transfer protein (alpha-TTP), which was identified as a product of the causative gene for familial isolated vitamin E (FIVE) deficiency, is a cytosolic liver protein which plays an important role in the efficient circulation of plasma vitamin E in the body. In the present study, we detected the message for alpha-TTP at low levels in some rat tissues including brain, spleen, lung and kidney. In the brain, the alpha-TTP transcript was detected predominantly in the cerebellar cortex, as revealed by in situ hybridization histochemistry. In the cerebellar cortex, clusters of the hybridization signal were aligned with the Purkinje cell layer, although the signal was not detected in the Purkinje cells, but in the small cells around the Purkinje cells. This distribution pattern strongly suggests that the message for alpha-TTP is expressed in the Bergmann glial cells. Combined with the previous observation that there was severe Purkinje cell loss in patients with FIVE deficiency, the present data suggest that vitamin E is supplied to the Purkinje cells from the surrounding Bergmann glial cells with the help of alpha-TTP.
Animals↗
Constitutively active Galpha12, Galpha13, and Galphaq induce Rho-dependent neurite retraction through different signaling pathways.
In neuronal cells, activation of a certain heterotrimeric G protein-coupled receptor causes neurite retraction and cell rounding via the small GTPase Rho. However, the specific heterotrimeric G proteins that mediate Rho-dependent neurite retraction and cell rounding have not yet been identified. Here we investigated the effects of expression of constitutively active Galpha subunits on the morphology of differentiated PC12 cells. Expression of GTPase-deficient Galpha12, Galpha13, and Galphaq, but not Galphai2, caused neurite retraction and cell rounding in differentiated PC12 cells. These morphological changes induced by Galpha12, Galpha13, and Galphaq were completely inhibited by C3 exoenzyme, which specifically ADP-ribosylates and inactivates Rho. The tyrosine kinase inhibitor tyrphostin A25 blocked the neurite retraction and cell rounding induced by Galpha13 and Galphaq. However, tyrphostin A25 failed to inhibit the Galpha12-induced neuronal morphological changes. On the other hand, inhibition of protein kinase C or elimination of extracellular Ca2+ blocked the neurite retraction and cell rounding induced by Galphaq, whereas the morphological effects of Galpha12 and Galpha13 did not require activation of protein kinase C and extracellular Ca2+. These results demonstrate that activation of Galpha12, Galpha13, and Galphaq induces Rho-dependent morphological changes in PC12 cells through different signaling pathways.
ADP Ribose Transferases↗
Evidence supporting an association between the DRB1 gene and schizophrenia in Japanese.
The authors attempted a replication of earlier studies that detected an association of HLA-DR4 and DR1 with schizophrenia. Japanese patients with schizophrenia (n = 266, DSM-III-R criteria) and Japanese controls (n = 283) were genotyped for DR1 and DR4 alleles using a combination of group-specific polymerase chain reaction (PCR) amplification and PCR-restriction fragment length polymorphism. Significant positive association with HLA-DR1 [odds ratio (OR) = 1.87, corrected p = 0.04] and a negative association with HLA-DR4 (OR = 0.63, corrected p = 0.02) was noted. DR1 and DR4 were independently associated with schizophrenia. The association of the DR1-positive/DR4-negative genotype with schizophrenia was modest (OR = 2.60, 95% confidence intervals = 1.38-4.89, corrected p = 0.008). Thus, these findings support an association of the HLA DRB1 gene locus with schizophrenia in the Japanese population. Since both DR4 and DR1 are positively associated with rheumatoid arthritis, our findings are not simply consistent with the known negative association between schizophrenia and rheumatoid arthritis.
Female↗
Switching of platelet-activating factor acetylhydrolase catalytic subunits in developing rat brain.
In a previous study, we demonstrated that Platelet-activating Factor (PAF) acetylhydrolase purified from bovine brain cortical cytosol consists of two mutually homologous catalytic subunits (alpha1 and alpha2) and one putative regulatory beta subunit. The latter is a product of the LIS1 gene, which is defective in the Miller-Dieker syndrome, a form of lissencephaly. In this study, we examined the expression patterns of these three subunits in the developing rat brain. All three subunits were expressed in embryonic brain, whereas only alpha2 and beta subunit were detected in the adult brain by Western blotting. Biochemical analyses revealed that the alpha1/alpha2 heterodimer and alpha2/alpha2 homodimer are major catalytic units of embryonic and adult brain PAF acetylhydrolases, respectively. The alpha1 transcript and protein were detected predominantly in embryonic and postnatal neural tissues, such as the brain and spinal cord. Furthermore, we found using primary cultured cells isolated from neonatal rat brain that alpha1 protein were expressed only in neurons but not in glial cells and fibroblasts. In contrast, alpha2 and beta transcripts and proteins were detected both in neural and non-neural tissues, and their expression level was almost constant from fetal stages through adulthood. These results indicate that alpha1 expression is restricted to actively migrating neurons in rats and that switching of catalytic subunits from the alpha1/alpha2 heterodimer to the alpha2/alpha2 homodimer occurred in these cells during brain development, suggesting that PAF acetylhydrolase plays a role(s) in neuronal migration.
1-Alkyl-2-acetylglycerophosphocholine Esterase↗
Purification, cDNA cloning, and expression of UDP-Gal: glucosylceramide beta-1,4-galactosyltransferase from rat brain.
Lactosylceramide synthase is an enzyme that catalyzes the transfer of galactose from UDP-Gal to glucosylceramide, and thus participates in the biosynthesis of most glycosphingolipids in mammals. We purified this enzyme over 61,000-fold to near homogeneity with a 29. 7% yield from rat brain membrane fractions. The isolation procedure included solubilization with Triton X-100, affinity chromatography on wheat germ agglutinin-agarose and UDP-hexanolamine-agarose, and hydroxylapatite column chromatography, followed by ion exchange chromatography. The final preparation migrated as a broad band with an apparent molecular mass of 61 kDa on SDS-polyacrylamide gel electrophoresis. This apparent molecular mass was reduced to 51 kDa by N-glycanase digestion, suggesting that the enzyme has a glycoprotein nature. The enzyme required Mn2+ for its activity, and glucosylceramide was its preferred substrate. The cDNA for the enzyme was cloned from a rat brain cDNA library. The cDNA insert encoded a polypeptide of 382 amino acid residues, with a molecular weight of 44,776. The polypeptide contained eight putative glycosylation sites and a 20-amino acid residue transmembrane domain at its N terminus. Amino acid sequence homology analysis revealed that this enzyme shared 39% homology with mouse beta-1, 4-galactosyltransferase (EC 2.4.1.38), which catalyzes the transfer of Gal to beta-1,4-GlcNAc in glycoproteins.
Amino Acid Sequence↗
Structure of a microbial homologue of mammalian platelet-activating factor acetylhydrolases: Streptomyces exfoliatus lipase at 1.9 A resolution.
BACKGROUND: Neutral lipases are ubiquitous and diverse enzymes. The molecular architecture of the structurally characterized lipases is similar, often despite a lack of detectable homology at the sequence level. Some of the microbial lipases are evolutionarily related to physiologically important mammalian enzymes. For example, limited sequence similarities were recently noted for the Streptomyces exfoliatus lipase (SeL) and two mammalian platelet-activating factor acetylhydrolases (PAF-AHs). The determination of the crystal structure of SeL allowed us to explore the structure-function relationships in this novel family of homologous hydrolases. RESULTS: The crystal structure of SeL was determined by multiple isomorphous replacement and refined using data to 1.9 A resolution. The molecule exhibits the canonical tertiary fold of an alpha/beta hydrolase. The putative nucleophilic residue, Ser131, is located within a nucleophilic elbow and is hydrogen bonded to His209, which in turn interacts with Asp177. These three residues create a triad that closely resembles the catalytic triads found in the active sites of other neutral lipases. The mainchain amides of Met132 and Phe63 are perfectly positioned to create an oxyanion hole. Unexpectedly, there are no secondary structure elements that could render the active site inaccessible to solvent, like the lids that are commonly found in neutral lipases. CONCLUSIONS: The crystal structure of SeL reinforces the notion that it is a homologue of the mammalian PAF-AHs. We have used the catalytic triad in SeL to model the active site of the PAF-AHs. Our model is consistent with the site-directed mutagenesis studies of plasma PAF-AH, which implicate Ser273, His351 and Asp296 in the active site. Our study therefore provides direct support for the hypothesis that the plasma and isoform II PAF-AHs are triad-containing alpha/beta hydrolases.
1-Alkyl-2-acetylglycerophosphocholine Esterase↗
p160 RhoA-binding kinase ROKalpha induces neurite retraction.
We previously reported that the activation of prostaglandin E receptor EP3 subtype caused neurite retraction via small GTPase Rho in the EP3B receptor-expressing PC12 cells (Katoh, H., Negishi, M., and Ichikawa, A. (1996) J. Biol. Chem. 271, 29780-29784). However, a potential downstream effector of Rho that induces neurite retraction was not identified. Here we examined the morphological effect of p160 RhoA-binding kinase ROKalpha, a target for RhoA recently identified, on the nerve growth factor-differentiated PC12 cells. Microinjection of the catalytic domain of ROKalpha rapidly induced neurite retraction similar to that induced by microinjection of a constitutively active Rho, RhoV14, whereas microinjection of the kinase-deficient catalytic domain of ROKalpha did not induce neurite retraction. This morphological change was observed even though C3 exoenzyme, which was known to inactivate Rho, had been preinjected. On the other hand, microinjection of the Rho-binding domain or the pleckstrin homology domain of ROKalpha inhibited the EP3 receptor-induced neurite retraction. These results demonstrate that ROKalpha induces neurite retraction acting downstream of Rho in neuronal cells.
Animals↗
Molecular cloning of cDNAs encoding alpha1, alpha2, and beta subunits of rat brain platelet-activating factor acetylhydrolase.
Brain intracellular platelet-activating factor acetylhydrolase (PAF-AH(Ib)) is a tertiary G-protein-complex-like heterotrimeric enzyme which is composed of alpha1, alpha2, and beta subunits and is implicated in stages of brain development such as the formation of the brain cortex. We have isolated and sequenced cDNA clones encoding these three subunits of rat brain PAF-AH(Ib). The amino acid sequences of brain PAF-AH has shown an extremely high homology among mammalian species. The tissue distribution of the three subunits was examined by Northern blot analysis. Although the mRNAs were detected in various organs, the ratio of the level of mRNA expression for the three subunits differed among rat tissues, raising the possibility that isoform(s) other than the heterotrimeric isoform exist in certain tissues.
1-Alkyl-2-acetylglycerophosphocholine Esterase↗
Imaging features of subcutaneous sarcoidosis.
OBJECTIVE: This report describes subcutaneous sarcoidosis, focusing on the radiological and magnetic resonance (MR) features of the disease. DESIGN AND PATIENTS: The cases of four patients (one male and three female, age range 36-75 years) who had subcutaneous sarcoidosis with no other organs affected were reviewed. Lesions were nodular in two cases, and in the other two were diffuse. RESULTS: Computed tomography (CT) demonstrated a well-defined, homogeneous, and enhanced lesion in the nodular cases. However, in the diffuse cases, CT showed a heterogeneous, honeycomb-like appearance and little enhancement. Angiography showed a fine stain in the arterial phase. MR imaging of the nodular lesions was homogeneous with a signal intensity similar to muscle on T1-weighted images but heterogeneous with a higher signal than muscle on T2-weighted images. Diffuse lesions showed a striped or mesh pattern with intermediate signal intensity on both T1- and T2-weighted images. Contrast-enhanced MR images showed slight enhancement. CONCLUSIONS: Subcutaneous sarcoidosis should be considered in the differential diagnosis when a patient presents with the radiological and MR features described.
Adult↗
Role of magnetization transfer imaging in bone tumors.
RATIONALE AND OBJECTIVES: The authors evaluated the role of magnetization transfer imaging in differentiation of bone tumors, with special emphasis on cartilaginous tumors. MATERIALS AND METHODS: Fifty-one patients with skeletal tumors or tumor-like lesions who had undergone magnetic resonance (MR) imaging were included. The tumors were divided into three groups according to their gross appearance and the origin of tissue: cyst, cartilaginous tumor, and noncartilaginous solid tumor. A gradient-recalled acquisition in the steady state sequence was used for MR imaging, and examinations were performed both with and without off-resonance magnetization transfer pulses. Magnetization transfer ratios were obtained as an indicator of magnetization transfer effect of the lesions and were compared. Then, the magnetization transfer ratios of all tumors in the cartilaginous tumor group were compared. The magnetization transfer ratios of benign and malignant solid tumors were also compared. RESULTS: The mean magnetization transfer ratio for cartilaginous tumors was 0.31 +/- 0.08 (standard deviation), and that of cysts and noncartilaginous solid tumors was 0.07 +/- 0.03 and 0.40 +/- 0.14, respectively. Comparisons between the three groups showed statistically significant intergroup differences in magnetization transfer ratio (P < .05). In the cartilaginous tumor category, enchondroma and low-grade chondrosarcoma had a lower magnetization transfer effect than chondroblastoma and mesenchymal chondrosarcoma. The mean magnetization transfer ratios of benign (n = 28) and malignant (n = 18) tumors were 0.35 +/- 0.11 and 0.39 +/- 0.15, respectively; there was no statistically significant intergroup difference (P = .14). CONCLUSION: Magnetization transfer imaging could be useful for categorizing bone tumors as cysts, cartilaginous tumors, or noncartilaginous solid tumors.
Adolescent↗
Interaction of poliovirus with its purified receptor and conformational alteration in the virion.
Polypeptides of amino acids 1 to 241 (PVR241) and 1 to 330 (PVR330) of the human poliovirus receptor (hPVR) were produced in a baculovirus expression system. PVR241 contained extracellular domains 1 and 2 of hPVR, and PVR330 contained extracellular domains 1, 2, and 3. These peptides were purified by immunoaffinity column chromatography with an anti-hPVR monoclonal antibody (MAb). After the purification, PVR241 and PVR330 appeared to retain their native conformation as judged by reactivity with an anti-PVR MAb that recognized domain 1 of hPVR in a conformation-dependent manner. The virulent Mahoney strain of poliovirus type 1 was mixed with the purified PVRs in various concentrations. An average of at least 43 PVR330 molecules were able to bind to one virion particle under the conditions used. The equilibrium dissociation constant between the PVR330 molecule and the PVR binding site (canyon) on the virion was determined to be 4.50 +/- (0.86) x 10(-8) M at 4 degrees C. Higher rates of conformational change of the virus (160S) to 135S and 80S particles were observed as the concentration of PVR330 was increased. In this in vitro system, the ratio of the amount of the 135S particle to that of the 80S particle seemed to be always constant. After the disappearance of the 160S particle, the amount of the 80S particle was not increased by further incubation at 37 degrees C. These results suggested that the 80S particle was not derived from the 135S particle under the conditions used in this study.
Animals↗
Two familial mesothelioma cases with high concentrations of soluble cytokeratin 19 fragment in pleural fluid.
We report two cases of diffuse malignant pleural mesothelioma occurring almost simultaneously in one family. Patient 1 was a 42-year-old Japanese man who had worked as an electrical engineer for 25 years. Patient 2, his mother, was 69 years old. She lived for 10 years with patient 1 after he started his work, and also worked at a shipyard herself for 6 years. The concentrations of cytokeratin subunit 19 fragment (CYFRA 21-1) in pleural fluid of the two patients were 1,500 ng/ml, and 1,200 ng/ml, respectively. Measurement of CYFRA 21-1 concentration in the pleural fluid may be a useful tool for a diagnosis of malignant mesothelioma.
Adult↗
An autopsy case of systemic hemangiomatosis with honeycomb-like liver and focal splenic sarcomatoid changes.
An unusual autopsy case of systemic hemangiomatosis associated with honeycomb-like liver and splenic sarcomatoid changes is presented. The patient suffered from high-output ventricular heart failure secondary to hepatic arteriovenous shunting with hepatic failure, ending fatally due to disseminated intravascular coagulation and pulmonary bleeding. Postmortem examination revealed the characteristic distribution of vasoformative tumors presenting in the hematopoietic system including the liver, bone marrow, and spleen, with the liver appearing characteristically honeycomb-like. While these vasoformative tumors were mostly benign-appearing, partial shifts toward sarcomatoid change were observed in the splenic lesions.
Angiomatosis↗
Benign asbestos pleural effusion associated with pulmonary aspergilloma.
A rare case of benign asbestos pleural effusion associated with aspergilloma is reported. A chest radiograph of a 75-year-old Japanese man who was admitted with right chest pain showed a right pleural effusion and nodular shadows in the right apex and left middle lung field. Thoracocentesis revealed an exudate with atypical mesothelial cells. An open lung biopsy showed aspergilloma in the right S2 area and no evidence of malignancy. Many reactive mesothelial cells were found in the pleura. A quantitative asbestos digestion study of the lung tissue biopsy showed high-grade asbestos exposure.
Aged↗
CT-guided percutaneous intervention using a simple laser director device.
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Biopsy, Needle↗