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Biomedical subjects

A Satoh

Publications and source records attributed to A Satoh.

At least 91 records · Page 5Linked to original sources
PubMed1997

Afadin: A novel actin filament-binding protein with one PDZ domain localized at cadherin-based cell-to-cell adherens junction.

A novel actin filament (F-actin)-binding protein with a molecular mass of approximately 205 kD (p205), which was concentrated at cadherin-based cell-to-cell adherens junction (AJ), was isolated and characterized. p205 was purified from rat brain and its cDNA was cloned from a rat brain cDNA library. p205 was a protein of 1,829 amino acids (aa) with a calculated molecular mass of 207,667 kD. p205 had one F-actin-binding domain at 1,631-1,829 aa residues and one PDZ domain at 1,016- 1,100 aa residues, a domain known to interact with transmembrane proteins. p205 was copurified from rat brain with another protein with a molecular mass of 190 kD (p190). p190 was a protein of 1,663 aa with a calculated molecular mass of 188,971 kD. p190 was a splicing variant of p205 having one PDZ domain at 1,009-1,093 aa residues but lacking the F-actin-binding domain. Homology search analysis revealed that the aa sequence of p190 showed 90% identity over the entire sequence with the product of the AF-6 gene, which was found to be fused to the ALL-1 gene, known to be involved in acute leukemia. p190 is likely to be a rat counterpart of human AF-6 protein. p205 bound along the sides of F-actin but hardly showed the F-actin-cross-linking activity. Northern and Western blot analyses showed that p205 was ubiquitously expressed in all the rat tissues examined, whereas p190 was specifically expressed in brain. Immunofluorescence and immunoelectron microscopic studies revealed that p205 was concentrated at cadherin-based cell-to-cell AJ of various tissues. We named p205 l-afadin (a large splicing variant of AF-6 protein localized at adherens junction) and p190 s-afadin (a small splicing variant of l-afadin). These results suggest that l-afadin serves as a linker of the actin cytoskeleton to the plasma membrane at cell-to-cell AJ.

Actins↗
PubMed1997

Transgenic copper/zinc-superoxide dismutase ameliorates caerulein-induced pancreatitis in mice.

The role of oxidative stress in acute pancreatitis was investigated by comparing the pathological features of caerulein pancreatitis between transgenic mice that overexpress human Cu/Zn-superoxide dismutase (SOD) and nontransgenic littermates. Both the elevation of serum amylase and the formation of pancreatic edema during the pancreatitis were significantly reduced in the transgenic mice compared with the nontransgenic littermates. In the transgenic mice, the pancreatitis-associated reduction of Cu/Zn-SOD activity in the pancreatic tissues was significantly smaller than that in the nontransgenic mice. These results provide direct evidence that the elevation of intracellular oxygen radicals is an important factor for the progress of acute edematous pancreatitis.

Animals↗
PubMed1997

Modulation of cell surface lectin receptors on K562 human erythroleukemia cells induced by transfection with annexin IV cDNA.

Annexin IV was found to be highly expressed in various human adenocarcinoma cell lines, but not in an erythroleukemia cell line, K562. We investigated the effects of transfection of human annexin IV cDNA into K562 cells on cell surface lectin receptors. cDNA transfectants were found to be more sensitive to cytotoxic lectins such as Ricinus communis agglutinin and wheat germ agglutinin than mock transfectants. The results of flow cytometric analyses with various lectins showed that the transfectants expressed more sugar chains which bind to Ulex europaeus agglutinin I and Maackia amurensis mitogen than mock transfectants. These results suggest that transfection of annexin IV cDNA increases the expression of alpha-2,3-sialylated and/or fucosylated sugar chains on the surface.

Annexin A4↗
PubMed1997

Isolation and characterization of a GDP/GTP exchange protein specific for the Rab3 subfamily small G proteins.

The Rab small G protein family, consisting of nearly 30 members, is implicated in intracellular vesicle trafficking. They cycle between the GDP-bound inactive and GTP-bound active forms, and the former is converted to the latter by the action of a GDP/GTP exchange protein (GEP). No GEP specific for each Rab family member or Rab subfamily has been isolated. Here we purified a GEP from rat brain with lipid-modified Rab3A as a substrate. The purified protein was specifically active on Rab3A, Rab3C, and Rab3D of the Rab3 subfamily. Of these subfamily members, Rab3A and Rab3C are implicated in Ca2+-dependent exocytosis, particularly in neurotransmitter release. This GEP (Rab3 GEP) was active on the lipid-modified form, but not on the lipid-unmodified form. Rab3 GEP showed a minimum molecular mass of about 200 kDa on SDS-polyacrylamide gel electrophoresis. We cloned its cDNA from a rat brain cDNA library and determined its primary structure. The isolated cDNA encoded a protein with a Mr of 177,982 and 1,602 amino acids, which showed no homology to any known protein. The recombinant protein exhibited GEP activity toward Rab3A, Rab3C, and Rab3D. Northern blot and Western blot analyses indicated that Rab3 GEP was expressed in all the rat tissues examined with the highest expression in brain.

Amino Acid Sequence↗
PubMed1997

Gallbladder emptying and cholecystokinin and pancreatic polypeptide responses to a liquid meal in patients with diabetes mellitus.

To investigate gallbladder motility and its regulation in patients with diabetes mellitus (DM), we examined the gallbladder response to an intraduodenal test meal by measuring the temporal course of plasma cholecystokinin (CCK) and pancreatic polypeptide (PP) levels. Eighteen patients with type 2 DM and 7 healthy subjects (controls) were enrolled. The gallbladder volume was calculated by the sum-of-cylinders method from ultrasonographic images, and plasma CCK and PP were measured by radioimmunoassays. No significant difference was found in either the gallbladder response or in the CCK response between patients with DM and controls. However, the fasting plasma PP level of patients with DM was more than tenfold higher than that of controls. The integrated PP response (IPPR) of patients with DM to the test meal was 8.3-fold higher than that of controls. When patients with DM were grouped according to whether they had been treated with insulin or not, the fasting plasma PP of patients with DM without insulin treatment was significantly higher than the level in those treated with insulin. These results suggest that overproduction of PP-like immunoreactive substance(s) may occur in patients with DM, but the high plasma PP immunoreactivity does not appear to be related to the fasting gallbladder volume or to gallbladder emptying and filling.

Adult↗
PubMed1997

Gastric mucosal blood flow response to stress in streptozotocin diabetic rats: regulatory role of nitric oxide.

To investigate cytoprotection against mucosal injuries of the stomach in patients with diabetes, we investigated gastric mucosal blood flow (GMBF), its response to a burn stress, and the involvement of nitric oxide (NO) in streptozotocin (STZ) diabetic rats. GMBF was measured by laser-Doppler velocimetry (LDV) and by the hydrogen gas clearance technique (HGC). The steady-state GMBF of STZ rats decreased according to the duration of diabetes, and insulin treatment blocked this decrease. Burn stress caused a rapid decrease in the GMBF. Reduction of the GMBF and gastric mucosal leakage of Evans blue (EB) after the burn stress were greater in the STZ rats than in the controls, but insulin treatment completely blocked this increase in EB leakage in the STZ rats. There was a significant negative correlation between the percent GMBF 3 h after the burn stress and EB leakage at the same time point. In the controls and the insulin-treated STZ rats, N-nitro-L-arginine (L-NNA), an NO synthase inhibitor, enhanced the decrease in postburn GMBF and EB leakage, but was without effect in the STZ rats. These results suggest that NO may be involved in the regulation of GMBF, and that persistent hyperglycemia may impair this regulation. These findings suggest that patients with diabetes have reduced cytoprotection against a variety of gastric mucosal injuries.

Animals↗
PubMed1997

In situ inhibition of vesicle transport and protein processing in the dominant negative Rab1 mutant of Drosophila.

Rab proteins play an essential role in vesicle transport. In particular, RAB1 is thought to participate in the transport of most membrane and secretory proteins. To investigate the role of RAB1 in developing or functioning cells in situ, we constructed transgenic, dominant-negative Rab1 mutants of Drosophila, and examined the protein transport and cellular and subcellular structures of mutant photoreceptor cells. In the transgenic fly, the expression of mutant RAB1 was induced by Gal4 protein, whose expression was triggered by heat treatment (37 degrees C) of the fly. Within several hours after the heat induction, the lumens of the rough endoplasmic reticulum (rER) became swollen, and Golgi bodies were disassembled into vesicle clusters. Corresponding to these changes in cell structure, rhodopsin transport was blocked between the rER and the Golgi body, as indicated by the accumulation of immature rhodopsin carrying a large high-mannose-type oligosaccharide chain. Long-term expression of mutant RAB1 caused the degradation of photoreceptive microvilli and the accumulation of numerous swollen rERs, whereas no distinct changes were found in the axonal regions. These results indicate that, in Drosophila photoreceptor cells, RAB1 contributes to the maintenance of local cell structure by mediating vesicle transport between the rER and Golgi body.

Amino Acid Substitution↗
PubMed1997

Characterization of human p33/41 (annexin IV), a Ca2+ dependent carbohydrate-binding protein with monoclonal anti-annexin IV antibodies, AS11 and AS17.

p33/41 (annexin IV) is a member of the family of Ca(2+)-dependent phospholipid binding proteins known as annexins. We previously described that bovine kidney p33/41 (annexin IV) has Ca(2+)-dependent carbohydrate binding activity. In this study, we purified human p33/41 (annexin IV) from the HT29, human colon adenocarcinoma cell line, as well as the bovine kidney annexin by affinity chromatography. Then, we prepared recombinant human p33/41 (annexin IV) expressed in Escherichia coli. The apparent size and the Ca(2+)-dependent carbohydrate binding properties of purified recombinant p33/41 (annexin IV) were indistinguishable from those of the bovine kidney protein. We also performed inhibition assays of carbohydrate binding and of phosphatidylserine/phosphatidylcholine liposome binding of recombinant p33/41 (annexin IV) with anti-p33/41 monoclonal antibodies (AS11 and AS17). We determined the epitopes recognized by the monoclonal antibodies by Western blot analysis using deleted-recombinant p33/41 (annexin IV). The monoclonal antibodies recognized domain 1 and/or 2 of p33/41 (annexin IV). The results of the inhibition assays and the determination of the epitope showed that a carbohydrate binding site is located at domains 3 and 4 of p33/41 (annexin IV) and on the cell surface.

Annexin A4↗
PubMed1997

Enantioselective fluorination of organic molecules. I. Synthetic studies of the agents for electrophilic, enantioselective fluorination of carbanions.

In order to develop novel methods for electrophilic and enantioselective fluorination of active methine compounds, preliminary experiments were carried out. The N-tosyl derivative 5 obtained from D-phenylglycine was fluorinated with FClO3 or diluted F2 gas to give the N-fluoro-N-tosyl derivative 6. N-tosyl- or N-mesyl-(S)-alpha-phenethylamine 7 or 8 was subjected to FClO3 fluorination to produce the corresponding N-fluoro derivative, 10 or 11, respectively. Enantioselective fluorination of some methine compounds was attempted employing the above N-fluoro agents. Best result was obtained when 2-benzyl-1-tetralone/KHMDS was treated with 10 to produce the fluorinated tetralone 17 in 53% yield with enantiomeric excess (ee) of 48%.

Anions↗
PubMed1997

Effect of coronary risk factors on coronary angiographic morphology in patients with ischemic heart disease.

We investigated the effects of hypercholesterolemia, hypertension, and diabetes mellitus, which are major coronary risk factors, on the angiographic morphology of coronary artery lesions in 204 patients with previous myocardial infarction or stable-effort angina: 39 patients with hypercholesterolemia (serum total cholesterol > 240 mg/dl) without hypertension and diabetes, 51 patients with hypertension without diabetes and hypercholesterolemia, 24 patients with diabetes without hypertension and hypercholesterolemia, and 90 patients without any of these 3 risk factors (control). Patients without coronary artery lesions were excluded. The severity of coronary artery lesions is expressed as the Gensini score and the morphology is classified according to Rosch's classification. The distribution of coronary artery lesions did not differ significantly between the 4 groups. The Gensini score was significantly higher in the hypercholesterolemia group than in the other groups (p < 0.05). Short concentric lesions were more frequent in the hypercholesterolemia group than in the control group (p < 0.01), and tubular regular lesions were more frequent in the hypertension and diabetes groups than in the control group (p < 0.01). These results suggest that hypercholesterolemia has a greater influence on the severity of coronary artery lesions than does hypertension or diabetes, and that the progression of coronary atherosclerosis may differ among patients with these risk factors.

Adult↗
PubMed1997

Effects of cabbage leaf protein concentrate on the serum and liver lipid concentrations in rats.

The effects of cabbage leaf protein concentrate (CLPC) on serum and liver lipid concentrations were determined in rats fed cholesterol-enriched and cholesterol-free diets. In rats fed the cholesterol-enriched diet with CLPC, total cholesterol, triacylglycerol and phospholipid concentrations in both the serum and liver, as well as the atherogenic index diet were significantly lower than those of the rats fed a casein diet. A supplement of methionine to the CLPC diet raised serum HDL-cholesterol and body weight gain, indicating that the addition of methionine to the CLPC diet is not only available to improve the nutritive value of CLPC but also to lower the atherogenic index. In rats fed the cholesterol-free diet, the liver total cholesterol and triacylglycerol concentrations of the CLPC-fed rats also showed lower values than those of the casein-fed rats, however, the serum total cholesterol concentration of the CLPC-fed rats did not differ from that of the casein-fed rats.

Animals↗
PubMed1997

[Total defect of metaiodobenzylguanidine (MIBG) imaging on heart in Parkinson's disease: assessment of cardiac sympathetic denervation].

This study was conducted to evaluate sympathetic cardiac innervation using MIBG imaging in PD. Uptake of MIBG was measured in 35 PD patients. Although normal MIBG uptake was observed in PD patients with HY stage l, PD with stage 3-5 revealed a total defect of visual MIBG imaging on heart area. Quantitative measurements of MIBG uptake assessed by the radioactivity ratio of cardiac to mediastinal tissue(H/ M) in early imaging was associated with the clinical severity of PD(control; 2.0 +/- 0.3, stage l; 2.0 +/- 0.1, stage 2; 1.6 +/- 0.4, stage 3-5; 1.3 +/- 0.1). In conclusion, homogeneous impairment of sympathetic cardiac innervation was observed in PD patients and this abnormality was associated with the clinical severity of PD, indicating that MIBG imaging of heart is useful not only for the evaluation of cardiac sympathetic impairment of PD but also for the diagnosis of PD.

3-Iodobenzylguanidine↗
PubMed1997

[A case of rapidly progressive IgA nephropathy with transient hypocomplementemia at onset].

We present a case of IgA nephropathy (IgAGN) which developed rapidly progressive glomerulonephritis and showed marked clinical improvement with treatment. The patient was a 7-year-old boy who initially presented with acute nephritic syndrome with hypocomplementemia. Although the renal function improved with normalization of the serum complement level, it deteriorated again progressively. The first renal biopsy revealed cellular crescents in about 70 percent of 43 glomeruli. Immunofluorescent microscopy demonstrated deposits of IgA, C3 and IgG in the mesangium; they were also deposited along the glomerular capillary walls. He was treated with plasma exchange associated with hemodialysis and methylprednisolone pulse therapy, followed by oral administration of prednisolone, cyclophosphamide and warfarin. Renal function recovered to the normal range about two months after the initiation of treatment. The second biopsy demonstrated a marked decrease in histological activity. In this case, transient hypocomplementemia at onset may indicate that acute glomerulonephritis caused exacerbation of clinically silent IgAGN. Aggressive therapy may be effective in patients with rapidly progressive IgAGN if treated at an early stage.

Child↗
PubMed1997

Codon recognition by artificial tRNA molecules with modified nucleosides in the anticodon.

Proteins with unnatural amino acids at specific positions can be produced through cell-free protein synthesis. The synthesis of such molecules can, in principle, be facilitated by improving the codon reading efficiency of the tRNA that inserts the unnatural amino acid. In the present study, we prepared tRNA molecules with 2'-O-methyl nucleosides at the second and third positions of the anticodon and measured their codon-reading efficiencies. The results indicated, contrary to our expectation, that the modification damaged the decoding function completely.

Base Composition↗
PubMed1996

Immunohistochemical study of utrophin and dystrophin at the motor end-plate in myasthenia gravis.

We studied the densities of utrophin and dystrophin at the motor end-plates of patients with myasthenia gravis (MG) using immunohistochemical analysis. The densities were compared with those found in patients with amyotrophic lateral sclerosis, Lambert-Eaton myasthenic syndrome and normal controls. Utrophin was reduced at the motor end-plates of MG patients, in association with a reduction of alpha-bungarotoxin binding sites. In contrast, the density of dystrophin at the motor end-plate of MG patients was not significantly different from that found in the controls. We conclude that, at the motor end-plate, utrophin may be more closely associated than dystrophin with the acetylcholine receptor, and that it plays a different role.

Cytoskeletal Proteins↗
PubMed1996

Expression of carbohydrate-binding protein p33/41 in human tumor cell lines.

We previously reported a new type of lectin, p33/41 (annexin IV), which was isolated from a bovine tissue extract [Kojima, K. et al. (1992) J. Biol. Chem. 267, 20536-20539]. When the expression of p33/41 (annexin IV) was surveyed in the lysates of 39 human tumor cell lines by SDS-PAGE, followed by Western blot analysis with polyclonal anti-bovine p33/41 and monoclonal anti-annexin IV (Z016, Zymed) antibodies, 21 cell lines were found to be reactive with the polyclonal antibody, whereas all 39 cell lines were stained with Z016. These results together with those obtained with standard proteins, annexins IV and V, suggested that the monoclonal antibody, Z016, recognizes annexin V, but not p33/41 (annexin IV). Therefore, we performed cDNA cloning of human p33/41 (annexin IV) to prepare a recombinant protein and raised monoclonal antibodies against the protein. Northern blot analysis with the cDNA as a probe showed that a human colon cancer cell line, HT29, contains p33/41 (annexin IV) mRNA of two sizes, 2.0 and 3.0 kb. The two monoclonal antibodies, AS11 and AS17, against the recombinant protein generated were useful for flow cytometric analysis, ELISA, Western blot analysis and immunoprecipitation. Flow cytometric analysis with AS17 showed that p33/41 (annexin IV) is located in the cytoplasm of HT29 cells, but not on the cell surface. However, one of the cell surface proteins first labeled with biotin and then solubilized with a detergent was immunoprecipitated with AS17. The results suggest the existence of a membrane spanning form of p33/41 (annexin IV).

Adenocarcinoma↗