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M Sakaguchi

Publications and source records attributed to M Sakaguchi.

At least 271 records · Page 15Linked to original sources
PubMed1995

Expression of rat cathepsin D cDNA in Saccharomyces cerevisiae: implications for intracellular targeting of cathepsin D to vacuoles.

To investigate the intracellular transport mechanisms of lysosomal cathepsin D in yeast cells, we produced cathepsin D in Saccharomyces cerevisiae by placing the coding region under the control of the promoter of the yeast glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene. Immunoblotting analysis by the use of an antibody specific for rat cathepsin D coding sequence produced an intermediate species which had a slightly higher molecular weight than that of the mature cathepsin D. Cell fractionation experiments demonstrated that the cathepsin D polypeptide was colocalized to the yeast vacuoles with the marker enzyme carboxypeptidase Y in a Ficoll step gradient. A biosynthesis study with pulse-chase kinetic analysis revealed that the precursor polypeptide was accurately sorted to the yeast vacuoles as determined by cell fractionation, and that N-linked carbohydrate modifications were not required for vacuolar sorting of this protein. To elucidate the role of the propeptide region of cathepsin D, which might function in the intracellular targeting to the vacuole, a deletion mutant of cathepsin D lacking the propeptide was prepared and its intracellular targeting was examined after transfection into yeast cells. Immunoblotting analysis demonstrated that the propeptide-deleted mutant protein was recovered in a low quantity as compared with that in the case of yeast cells expressing the wild-type protein in the isolated vacuolar fraction. Immunofluorescence analysis revealed that the deletion mutant protein appeared to be accumulated within the intracellular small vesicles but not in the carboxypeptidase Y-positive vacuoles. Overall, these results indicate that the rat cathepsin D precursor polypeptide is recognized by mechanisms similar to those involved in the intracellular sorting of vacuolar proteins through the ER/Golgi/vacuolar sorting pathway in yeast cells, and that the propeptide has an important function in translocation of the cathepsin D polypeptide to the vacuole.

Animals↗
PubMed1995

Malfolded cytochrome P-450(M1) localized in unusual membrane structures of the endoplasmic reticulum in cultured animal cells.

A conserved region containing three to five proline residues is present just behind the signal-anchor sequence in the amino terminal portion of most microsomal cytochrome P-450s. We have shown that the proline residues are crucial for correct folding in Schizosaccharomyces pombe cells by using mutants of P-450(M1) in which one to three of the proline residues were changed to alanine. To examine the effects of the mutations on the intracellular localization of P-450s, they were expressed in COS-7 cells. They were found to be localized only in the perinuclear loci as patched structures like the Golgi apparatus, while the wild-type P-450(M1) is localized in the reticular structures which are typical for the ER membrane. However, treatment of the cells with Brefeldin A had no effect on the patched structures. Upon co-expression with another ER membrane protein, CD4D, which possesses a double lysine motif, the expressed CD4D was localized not only in the patched structures as the mutated P-450(M1)s, but also in the reticular structures of ER. When the cells were homogenized and then fractionated, the mutated P-450(M1) was recovered mainly in the low-speed precipitate and in the fractions of much higher density than the normal ER membrane. On electron microscopic observation, unusual membranous bodies were observed near the nucleus only when the mutated P-450(M1) was expressed.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

Suppressive action of lansoprazole on gastric acidity and its clinical effect in patients with gastric ulcers: comparison with famotidine.

We studied the action on acid secretion of lansoprazole compared with famotidine by 24-h intragastric pH monitoring, evaluated its clinical effects prospectively, and assessed the importance of acid inhibition in gastric ulcer patients. Twenty symptomatic patients with active gastric ulcers diagnosed by endoscopy were assigned to a lansoprazole (LAN) group (lansoprazole 30 mg q.d., n = 10) or a famotidine (FAM) group (famotidine 20 mg b.i.d., n = 10). There were no differences between the groups in pretreatment pH profiles or background factors such as age, sex, smoking, previous ulcer therapy, ulcer site, or Helicobacter pylori infection. The FAM group showed a continuous increase in intragastric pH during the night, with low pH values except for a transient increase associated with food intake during the day. However, the LAN group showed a more neutral pH throughout the day, with pH-3 holding time ratios of 99.0% for 24 h, 98.3% at night, and 99.8% during the day, compared with 68.0, 76.5, and 59.4%, respectively, in the FAM group. The healing rate was also higher in the LAN group. We conclude that inhibition of gastric acidity is important in ulcer therapy and that lansoprazole is superior to famotidine in promoting ulcer healing.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1995

Clinical study on the pathophysiology and treatment of PPI-resistant ulcers.

We studied the gastric acidity, gastric emptying, and proton pump inhibitor (PPI) plasma levels in 10 patients with PPI-resistant ulcers. The pH3 holding-time ratio was low in nine of these patients, with an average ratio of only 39%. PPI plasma levels in those patients were also much lower than in those with nonresistant ulcers. Gastric emptying, determined by the acetaminophen method, was reduced in all 10 patients. Therefore, PPI-resistant ulcers appear to result from insufficient inhibition of gastric acidity, with reduced gastric emptying interfering with the absorption of PPIs. In patients with mild reductions in gastric emptying, PPI plasma levels increased after a change from single-unit enteric-coated tablets (omeprazole) to multiunit enteric-coated granules in capsules (lansoprazole). This change in formulation markedly inhibited gastric acidity and led to rapid healing. In patients with moderate reductions in gastric emptying, doubling the dose of lansoprazole was effective. In patients with severely reduced gastric emptying, there appeared to be a limit to the effectiveness of oral administration of PPIs. Changing the formulation and doubling the dose to compensate for reduced gastric emptying are effective approaches in the treatment of patients with PPI-resistant ulcers.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1995

Expression of MAGE-1 gene by esophageal carcinomas.

Expression of the MAGE genes encoding tumor-rejection antigens on HLA-A1 and -Cw1601 recognized by cytotoxic T lymphocytes was investigated in esophageal carcinomas at the mRNA level by the semiquantitative reverse transcription-polymerase chain reaction method. MAGE-1 and -2 genes, but not MAGE-3, -3/-6 and -4a/-4b genes, were expressed in substantial proportions of the primary esophageal carcinomas and their metastatic lymph nodes. The proportion of MAGE-positive samples in the primary esophageal carcinomas correlated with the T factor of the TNM classification (pT1: 2 of 12 tumors, pT2: 1 of 6, pT3: 12 of 29, and pT4: 7 of 18). These results have important implications for specific immunotherapy of esophageal carcinomas using MAGE-1 gene product.

Antigens, Neoplasm↗
PubMed1995

Sensitivity to two major allergens (Cry j I and Cry j II) in patients with Japanese cedar (Cryptomeria japonica) pollinosis.

BACKGROUND: Japanese cedar (Cryptmeria japonica: CJ) pollinosis is one of the most important allergic diseases in Japan. Recently, the second major allergen (Cry j II) was isolated from CJ pollen. There have been no prevalence studies of sensitivity to Cry j I and Cry j II among a large number of patients with pollinosis. OBJECTIVE: This study was conducted to evaluate the prevalence of sensitivity to Cry j I and Cry j II. We measured specific IgE antibodies to these allergens in the sera of 145 patients. Furthermore, comparison of the sensitivity to Cry j I and Cry j II was examined by the histamine release assay. METHODS: Specific IgE antibodies to Cry j I and Cry j II were assayed by a fluorometric ELISA. Allergen-specific histamine release was measured by a radioimmunoassay kit. RESULTS: More than 90% of 145 patients had specific IgE antibodies to both allergens, the remainder had specific IgE to either one or the other. There were seasonal changes in the level of specific IgE. The changes in the levels of anti-Cry j II IgE antibodies were parallel to those of anti-Cry j I IgE. The histamine release assay with leucocytes from the patients demonstrated that the allergenic potency of the two allergens is almost the same. CONCLUSION: Cry j II is an as important a major allergen as Cry j I.

Adult↗
PubMed1995

Characterization of CD4+ T helper cells in patients with Kawasaki disease (KD): preferential production of tumour necrosis factor-alpha (TNF-alpha) by V beta 2- or V beta 8- CD4+ T helper cells.

KD is an acute febrile illness in children characterized by coronary arteritis accompanied by aneurysm and thrombotic occlusion. The etiology of KD is unknown. It has been recently reported that KD is associated with the selective expansion of V beta 2+ and V beta 8.1+ T cells in peripheral blood lymphocytes (PBL), by studying the T cell receptor (TCR) repertoire of in vitro activated T cells. KD may therefore be caused by a superantigen [1-3]. To understand better the immunopathology of KD, we investigated TCR V beta 2 and V beta 8.1 expression on both the T cells of freshly isolated PBL and T cell clones (TCC) from patients with KD. Cytokine production by TCC was also studied. Blood samples were obtained from patients with acute (n = 20) and convalescent (n = 20) KD, age-matched children with non-infectious diseases (n = 18), and healthy adults (n = 20). Among these four groups, there were no significant differences in the percentages of either V beta 2+ or V beta 8.1+ T cells of freshly isolated PBL. The same was true for the CD4+ or CD8+ T cell subsets. One hundred and five TCC (98 CD3+ CD4+ CD8- and seven CD3+ CD4- CD8+) established from the affected skin, lymph node or PBL of six patients with KD were also negative for either V beta 2 or V beta 8.1 TCR. Sixty-eight of 105 TCC (65%) produced detectable levels (> 5 pg/ml) of TNF-alpha (6-1016 pg/ml), in the absence of any stimuli. In contrast, only 11 (10%) of 105 TCC or 7 (7%) of 97 TCC produced detectable levels of IL-2 or IL-6, respectively, in the absence of any stimuli. Stimulation with phytohaemagglutinin (PHA) and phorbol myristate acetate (PMA) induced most TCC to produce higher amounts of TNF-alpha, IL-2 and IL-6. These results suggest that CD4+ T helper cells expressing TCR-beta other than V beta 2 or V beta 8 receptor, primarily through TNF-alpha production, are involved in the immunopathology of KD.

Adult↗
PubMed1995

Chemical restraint by medetomidine-ketamine and its cardiopulmonary effects in pigs.

Chemical restraint induced by medetomidine-ketamine (M-K) combination was evaluated compared with that by xylazine-ketamine (X-K) in pigs. The duration of restraint by M-K was 49.4 +/- 13.5 min (mean +/- SD) and longer than that by X-K (34.6 +/- 17.2 min), but the difference was not significant. The effect of X-K was not stable, since one of five pigs was restrained only for 6 min. Both combinations produced muscle relaxation. The duration of muscle relaxation in M-K was 43.6 +/- 12.7 min and was significantly longer than that in X-K (21.0 +/- 14.0 min). M-K combination had a slightly stimulative effect on the cardiovascular system, but scarcely changed the respiratory parameters. This limited effect on cardiopulmonary system was an advantage of M-K combination for chemical restraint in pigs. These results indicated that M-K combination is suitable for chemical restraint with prolonged muscle relaxation and has limited cardiopulmonary effects in pigs.

Anesthetics↗
PubMed1995

Anti-neutrophil cytoplasmic antibody for proteinase 3 in a child with polyarteritis nodosa.

We report a case of a 15 year old boy with polyarteritis nodosa associated with antineutrophil cytoplasmic antibody (ANCA) against proteinase 3 (PR3). After months of steroid and immunosuppressant therapy, the symptoms subsided and the polyaneurysms almost disappeared. The levels of anti-PR3 antibody and of cytokines also decreased. The results indicate that ANCA is a good indicator of this disease activity, and may play some pathogenic role in the disease.

Adolescent↗
PubMed1995

Hypersensitivity to Japanese cedar (Cryptomeria japonica) pollen in dogs.

Four of 51 dogs with chronic dermatitis were made to react to crude Japanese cedar (Cryptomeria japonica, CJ) pollen allergen by the intradermal skin test (IDST). These four dogs had specific IgE to CJ as determined by Prausnitz-Küstner test. In the provocation test, nasal discharge increased 5 to 20 min after introduction of the crude CJ pollen allergen into the nasal cavities, in two of three dogs. These results demonstrated that these dogs had hypersensitive to CJ pollen, which might be a cause of atopic disease in dogs.

Allergens↗
PubMed1995

Cytolytic action of stored human milk on blood cells in vitro.

Stored human milk induced cytolysis on various types of blood cells depending on the storage time and temperature. When separated by centrifugation after storage for 24 h at 4 degrees C, the cream, not whey, induced cytolysis. When separated and heated for 30 min at 56 degrees C before storage, neither cream or whey induced cytolysis. When the cream was heated at 56 degrees C for 30 min and mixed with non-heat-treated whey before being storage for 24 h at 4 degrees C, it induced cytolysis. When bile salt was added to whole milk before storage, the cytolytic activity was enhanced. When eserine was added, the cytolytic activity was suppressed. Thin layer chromatography showed that stored milk, not fresh milk, contained free fatty acids which caused a similar degree of cytolysis as stored whole milk. These results indicated that the cytolysis is due to the free fatty acids which were produced from triglycerides catalyzed by the lipase in milk.

Animals↗
PubMed1995

Subjective vertical and vestibular lesion.

Patients with peripheral vestibular disorders may experience postural instability in the standing position, which means disorientation in their environment. The disturbed vestibular function in light reflects the postural instability in space. The present study investigates the relationship between the subjective vertical and the vestibular lesion. The subjects were patients with unilateral vestibular lesion, and the control subjects had no past history of vestibular lesion or any present vestibular lesion. A straight line consisting of 5 spotlights projected on a dome-shaped screen was concentrically moved like a stylus by pressing buttons. We measured the subjective vertical of the subjects using a 5-spotlight straight-line (spotlight-line) on a dome-shaped screen in front of which the subjects were placed. The result showed that the patients with unilateral peripheral disorder had a statistically significantly larger deviation to the impaired ear side, especially when the spotlight-line was moved from the impaired side, as compared with controls.

Adult↗
PubMed1995

Kawasaki disease.

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Coronary Aneurysm↗
PubMed1995

[A case of successful redo-operation for active prosthetic valve endocarditis after modified Bentall operation].

A redo-operation for active prosthetic valve endocarditis after modified Bentall operation is reported. A 42-year-old man associated with Marfan syndrome was transferred to our hospital with complaints of high fever and general fatigue. A modified Bentall operation for acute aortic dissection was done five years ago. The aortic arch and descending thoracic aorta were replaced with prosthetic graft because of aneurysmal dilatation four years ago. Transesophagial echogram revealed a developing vegetation below the prosthetic valve and at the left ventricular outflow. A redo-operation of translocation method with Pieler method for coronary reconstruction was performed using a prosthetic valve of SJM 21 mm in size. After operation, hemolysis suddenly appeared and hepatic dysfunction gradually progressed. Reoperation was necessary for the redo-operation and and a SJM 21 mm valve was replaced with a new 25 mm SJM valve interposed between the graft. Hemolysis was immediately improved. A redo operation of translocation method with Pieler method for coronary reconstruction showed a good results.

Adult↗
PubMed1994

Recognition of mitochondria-targeting signals by a cytosolic import stimulation factor, MSF.

MSF, a mitochondrial import stimulation factor purified from rat liver cytosol, is an ATP-dependent precursor protein conformational modulator. As a step toward understanding the specificity of substrate recognition by MSF, various synthetic peptides were examined for their ability to induce MSF ATPase activity. The peptides corresponding to various mitochondria-targeting signal sequences elicited significant ATPase activity. MSF bound the synthetic mitochondrial signal peptides, and ATP hydrolysis caused dissociation of the peptides from MSF. Basic amino acid residues in the signal peptides seemed to be essential for recognition. Thus, MSF is a member of the polypeptide chain-binding protein family with unique recognition specificity and is distinct from the hsp70 family of proteins.

14-3-3 Proteins↗
PubMed1994

MSF, a novel cytoplasmic chaperone which functions in precursor targeting to mitochondria.

Mitochondrial import stimulation factor (MSF) unfolds wheat germ lysate synthesized aggregated mitochondrial precursor proteins and stimulates their mitochondrial import in an ATP dependent manner. Here we analysed the function of MSF mainly by utilizing chemically pure adrenodoxin precursor (pAd). MSF bound to the unfolded pAd and prevented it from losing import competence and also restored the import competence of the aggregated pAd dependent on ATP hydrolysis. The import incompetent aggregated mitochondrial precursors induced the ATPase activity of MSF and the activity was strongly inhibited by isolated mitochondrial outer membrane (OM) but not by trypsin treated outer membrane (tOM). The precursor induced ATPase activity of N-ethylmaleimide (NEM)-treated MSF was not inhibited by OM. In this context, the MSF-precursor complex specifically bound to OM and binding was abolished both by the treatment of OM with trypsin and by the treatment of MSF with NEM. These results show that MSF is a novel cytoplasmic chaperone protein with a mitochondrial precursor-targeting function.

Adenosine Triphosphatases↗
PubMed1994

Lysophosphatidylcholine from white muscle of bonito Euthynnus pelamis (Linnaeus): involvement of phospholipase A1 activity for its production.

A fairly large amount of lysophosphatidylcholine (LPC) was detected in the fresh muscle of bonito Euthynnus pelamis (Linnaeus). The major fatty acid esterified in LPC were highly unsaturated fatty acids, such as docosahexaenoic and eicosapentaenoic acids, and the form was mainly composed of 1-lyso-2-acyl-sn-glycero-3-phosphocholine (1-LPC). The content of this species continued to increase during 4 months of frozen storage and then decreased. Phospholipase A1 activity detected in the bonito muscle was supposed to be responsible for the accumulation of LPC.

Animals↗