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J Nagai

Publications and source records attributed to J Nagai.

At least 55 records · Page 3Linked to original sources
PubMed1996

Heat-induced chaperone activity of HSP90.

The 90-kDa stress protein, HSP90, is a major cytosolic protein ubiquitously distributed in all species. Using two substrate proteins, dihydrofolate reductase (DHFR) and firefly luciferase, we demonstrate here that HSP90 newly acquires a chaperone activity when incubated at temperatures higher than 46 degrees C, which is coupled with self-oligomerization of HSP90. While chemically denatured DHFR refolds spontaneously upon dilution from denaturant, oligomerized HSP90 bound DHFR during the process of refolding and prevented it from renaturation. DHFR was released from the complex with HSP90 by incubating with GroEL/ES complexes in an ATP-dependent manner and refolded into the native form. alpha-Casein inhibited the binding of DHFR to HSP90 and also chased DHFR from the complex with HSP90. These results suggest that HSP90 binds substrates to maintain them in a folding-competent structure. Furthermore, we found that HSP90 prevents luciferase from irreversible thermal denaturation and enables it to refold when postincubated with reticulocyte lysates. This heat-induced chaperone activity of HSP90 associated with its oligomerization may have a pivotal role in protection of cells from thermal damages.

Animals↗
PubMed1996

Regulation of p-aminohippurate transport by protein kinase C in OK kidney epithelial cells.

We studied the effect of phorbol 12-myristate 13-acetate (PMA), a phorbol ester which activates protein kinase C, on p-aminohippurate (PAH) transport in OK cells. PMA (10(-7) M) almost completely inhibited the transcellular transport of PAH across OK cell monolayers from the basal to the apical side, as well as the accumulation of PAH in the cells. The uptake of PAH across the basolateral membrane of OK cells was inhibited by PMA in a time-and dose-dependent fashion. Exposing the cells with other protein kinase C activators such as active phorbol esters and diacylglycerols also resulted in a significant inhibition of basolateral PAH uptake, but the inactive phorbol ester, 4 alpha-phorbol 12,13-didecanoate, had no effect. The inhibition of basolateral PAH uptake by PMA was blocked by staurosporine, an inhibitor of protein kinase C. Cycloheximide, actinomycin D, colchicine, and cytochalasin D did not affect the inhibitory effect of PMA on basolateral PAH uptake. These results suggested that the PAH transport system in OK cells is under the regulatory control of protein kinase C.

Animals↗
PubMed1996

[MR relaxation times in diffuse bone marrow disorders: evaluation of their clinical usefulness in differentiation between leukemia and anemia].

T1 and T2 relaxation time measurements of the femoral marrow were performed in 20 patients with acute myeloid leukemia (AML) and 9 patients with iron deficiency or other severe anemia who had shown diffuse abnormal signals on MR imaging of the femoral marrow. The ability of T1 and T2 values to differentiate between leukemic infiltration and hyperplastic hematopoietic marrow was evaluated. T1 and T2 ratios (T1 abnormal marrow/T1 normal marrow and T2 abnormal/T2 normal) were calculated, and the ratios of T1 to T2 (T1/T2) and of the T1 ratio to the T2 ratio (T1 ratio/T2 ratio) were also analyzed. Diffuse infiltrative marrows revealed prolonged T1 relaxation times in all patients with AML and other severe anemia, and it was not possible to distinguish the two groups of diseases on the basis of T1 values. The T2 relaxation times varied widely in AML, but the mean T2 value of the AML group was not statistically significantly different from that of the anemia group. There were also no significant differences in the T1 ratio, T2 ratio, T1/T2, and the T1 ratio/T2 ratio between leukemic infiltration and hyperplastic hematopoietic marrow. We concluded that measurement of T1 and T2 relaxation times was of limited clinical importance for the histological characterization of diffuse bone marrow disorders.

Adult↗
PubMed1996

Atopic dermatitis successfully treated by eradication of Helicobacter pylori.

A relationship between allergic diseases and Helicobacter pylori infection has recently been noted. We report a case of atopic dermatitis and H. pylori infection in a 14-year-old girl. She had had widespread diffuse skin erythema with erosions and pigmentation since the age of 3 years. Endoscopically, there was chronic antral gastritis with H. pylori infection and histological eosinophilic infiltration. A high titer of H. pylori-specific IgG was present in serum. She was treated with a proton pump inhibitor (lansoprazole 60 mg), an antibiotic (clarithromycin 800 mg), and plaunotol (a mucosal protective agent, 480 mg) for 2 weeks to eliminate the infection. After 10 days of treatment, erythema and itching were more widespread and vesicle formation was seen on the foot. Generalized skin lesions abated a few days later. After eradication of the bacterium by the treatment, eosinophils decreased from 38.8% to 19.0%, and the clinical signs of atopic dermatitis almost disappeared. Serum gastrin level and the pepsinogen I/II ratio were normalized and histological findings of gastric mucosa showed improvement. H. pylori-specific IgE antibody, analyzed by the Western blot method, gradually decreased with the eradication treatment.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1996

[MR imaging of the femoral marrow in adult acute leukemia: correlation of MRI patterns with FAB subtype and prognosis].

MR imaging of the femoral marrow was performed in 36 patients with untreated acute myeloid leukemia (AML) and 7 patients with acute lymphocytic leukemia (ALL). The MRI appearance was classified into five patterns: 1) fatty marrow; 2) faint signal; 3) nodular pattern; 4) heterogeneous infiltration; and 5) diffuse infiltration. The MRI patterns of the femoral marrow were compared among the FAB subtypes of acute leukemia, and the MRI patterns were correlated with prognosis. All five MRI patterns were observed in the femoral marrow in adult acute leukemia, and diffuse infiltration was most commonly seen (41.9%). A completely fatty marrow was also depicted in two cases (4.7%) and faint signal in four cases (9.3%) in spite of untreated acute leukemia. The M2 subtype of AML tended to be demonstrated as a minimally abnormal MRI finding, which was significantly different from the other types of AML. The patients who showed fatty marrow or faint signal were thought to have a good prognosis, while diffuse or heterogeneous infiltration was regarded as a poor prognostic sign. However, there were some exceptions to these rules, and no significant differences were revealed in prognosis between minimally abnormal and advanced MRI patterns. We concluded that MRI of the femoral marrow could be useful in the assessment of tumor volume of adult acute leukemia, and that there were limitations to predicting prognosis on the basis of the MRI manifestations.

Acute Disease↗
PubMed1995

The role of ATP hydrolysis in the function of the chaperonin GroEL: dynamic complex formation with GroES.

In order to understand the role of ATP hydrolysis of the chaperonin GroEL during protein folding, we have studied GroEL-GroES complex formation in the presence of ATP or ADP by using capillary electrophoresis and surface plasmon resonance. Capillary electrophoresis analysis showed that the GroEL 14-mer and GroES 7-mer formed a 1:1 complex in the presence of ATP. In the presence of ADP, both the association and dissociation rates of the complex were slower by about one order of magnitude than the rates in the presence of ATP at 25 degrees C. The implications of such a stable complex on the overall mechanism of chaperonin function are discussed.

Adenosine Diphosphate↗
PubMed1995

In vivo effect of GroESL on the folding of glutamate racemase of Escherichia coli.

The overexpression of the murI (glr) gene, which encodes the glutamate racemase of Escherichia coli, resulted in the formation of inclusion bodies of the enzyme, and little activity was found in the soluble fraction of the transformant cells. The coexpression of the groESL gene with murI caused an in vivo solubilization of glutamate racemase in an active form. We isolated the active enzyme and purified it effectively.

Amino Acid Isomerases↗
PubMed1995

Specificity of p-aminohippurate transport system in the OK kidney epithelial cell line.

Substrate specificity of the p-aminohippurate (PAH) transport system was investigated in the OK kidney epithelial cells. PAH uptake by OK cells from the basal side was inhibited by beta-lactam antibiotics such as benzylpenicillin (PCG) and cefazolin. The inhibition of PAH uptake by PCG was competitive and the Ki value was calculated as 108.8 microM. Transcellular transport of PCG across OK cell monolayers occurred unidirectionally from the basal to apical side, and transcellular transport and basolateral uptake were inhibited by PAH, probenecid and beta-lactam antibiotics. The basolateral uptake of cefazolin and cefotiam was also inhibited by PAH and probenecid. The basolateral uptake of PAH and PCG were not affected by aliphatic dicarboxylates with 3 or 4 carbon atoms, but were strongly inhibited by those with 5 or 6 carbon atoms. The inhibitory effect became weaker for a longer dicarboxylate with 7 carbon atoms, then increased again with increasing number of carbon atoms. Such a pattern of inhibition by dicarboxylates is essentially the same with that observed in rat renal proximal tubules in situ. These findings suggest that the PAH transport system in OK cells has a substrate specificity similar to that in rat renal proximal tubules, which is involved in the active secretion of various organic anions including drugs.

Animals↗
PubMed1995

[Detection of nuclear antigen within the leukemic cells using immunocytochemical technique].

Immunocytochemical methods were examined for their sensitivity in the detection of nuclear antigens (proliferating cell nuclear antigen, Ki-67 associated proliferative antigen and p53 protein) in the leukemic cells. A comparative study of the biotin streptavidin enhanced peroxidase technique, the biotin streptavidin enhanced alkaline phosphatase technique and the indirect immunoperoxidase technique showed that the indirect immunoperoxidase technique was more sensitive than the other techniques for detecting p53 protein. The results of several fixation methods demonstrated that formalin and methanol, formalin and ethanol (1:9) and buffered formalin acetone gave good results for detecting p53 protein. In the eosinophils and neutrophils the endogenous peroxidase reaction disappeared after microwave heating for over three minutes. Thus enzyme pre-blocking of blood smears could be omitted. Four solutions for microwave treatment were tested. Excellent antigen retrieval was obtained with pH6.4, pH7.4 phosphate buffer saline and pH6.0 citric acid. However, the nuclear antigens could not be retrieved and the positive reaction could not be obtained after the treatment with distilled water. The optimal microwave heating time was five to ten minutes. The indirect immunoperoxidase technique performed using microwave treatment under these optimal conditions may be potentially applicable for detecting low levels of nuclear antigens in the leukemic cells within conventional blood smears.

Humans↗
PubMed1995

[MR imaging findings of the femoral marrow in myelodysplastic syndrome].

MR imaging of the femoral marrow was performed in 30 patients with myelodysplastic syndrome (MDS), 11 cases of which evolved to acute myeloid leukemia (AML). The MRI appearance was classified into five patterns: 1) fatty marrow; 2) faint signal; 3) nodular pattern; 4) heterogeneous infiltration; and 5) diffuse infiltration. For each type of MDS, MRI patterns of the femoral marrow were evaluated and compared with those in normal subjects as well as in patients with aplastic anemia. Signal intensity alteration, a low signal on T1-weighted SE image and a high signal on STIR image, began in the proximal femoral marrow almost symmetrically in patients with MDS. The area of abnormal signal intensity tended to gradually extend towards the distal portion of the femur as the disease progressed. MRI patterns of the femoral marrow correlated with marrow cellularity, and diffuse marrow infiltration was noted in patients with a more advanced type of MDS or with severe anemia. There were limitations to making an accurate diagnosis of the MDS type on the basis of the MRI pattern. Progression of the MRI appearance in the course of MDS was thought to be a sign suggesting evolution to AML. It was difficult to differentiate hypoplastic MDS from aplastic anemia, although the nodular pattern was commonly seen in the latter disease.

Adult↗
PubMed1995

Lines of mice selected for reproductive longevity.

Two lines of mice selected for reproductive longevity were compared with one unselected control line to examine longevity and lifetime performance such as number of parturitions during lifetime. Mice were pair mated at about 8 weeks of age and cohabited throughout life. Litter size was reduced to eight at birth in selected line 121 and unselected control line 221, but not in selected line 141. At generation 16, the average number of days from mating to the last parturition was 240.8, 243.0 and 134.6 for lines 121, 141 and 221, respectively. Selected lines 121 and 141 had 80% and 93%, respectively, greater number of parturitions during their lifetimes than the control line. Mean litter size at the early stage of reproduction was similar in the selected and control lines, but persistency of reproduction differed markedly. The average number of young born alive per breeding pair during a lifetime was 77.2, 82.8 and 45.9 for lines 121, 141 and 221, respectively. Data from the short-lived half of the mouse lines showed that mean lifespan was 17% longer in the selected lines 121 and 141 (377.5 and 436.5 days, respectively) than the control line 221 (346.8 days), and phenotypic and genetic correlations between reproductive longevity and lifespan were in the neighbourhood of 0.75 and 0.25, respectively. It was concluded that reproductive longevity was improved through selective breeding and lifespan increased as a correlated response to selection for increased reproductive longevity. The mouse lines derived from this study represent a unique mammalian model for studying various aspects of aging and longevity.

Animals↗
PubMed1994

Differential sensitivity of organic anion transporters in rat renal brush-border membrane to diethyl pyrocarbonate.

The effect of various chemical modifiers on p-aminohippurate (PAH) uptake by a potential-sensitive system and by an anion exchanger was studied in rat renal brush-border membrane vesicles. Among various chemical modifiers, diethyl pyrocarbonate (DEPC) selectively inhibited potential-sensitive PAH uptake but not the uptake by the anion exchanger. The inhibitory effect of DEPC on potential-sensitive PAH uptake was not due to the facilitated dissipation of membrane potential, which was evidenced by the studies with a potential-sensitive fluorescence dye diS-C3(5). The potential-sensitive PAH uptake was inhibited by DEPC in a concentration-dependent manner, and kinetic analysis showed that the decreased uptake of PAH in DEPC-treated vesicles was due to the decrease of Vmax. The inhibition of the PAH uptake was protected by the presence of organic anions during the DEPC treatment. These findings indicate that PAH transport by the potential-sensitive system and by the anion exchanger is mediated by structurally distinct transporters. Amino acid residue(s) modified by DEPC, most likely a histidine residue, should play an important role in the potential-sensitive transport of PAH in rat renal brush-border membrane.

Animals↗
PubMed1994

Chaperonin GroE and ADP facilitate the folding of various proteins and protect against heat inactivation.

In the presence of ADP, the molecular chaperones GroEL and GroES from Escherichia coli not only facilitated the refolding of various proteins, but also prevented their irreversible heat inactivation in vitro. Without nucleotides the refolding reactions were arrested by GroEL. Addition of GroES and ADP to the reaction mixture initiated the refolding reactions and the enzyme activities were regained efficiently. The presence of GroE (GroEL and GroES) and ADP also protected against heat inactivation of native enzymes at various temperatures. These findings suggest that in the presence of GroES, nucleotide binding is an important event in the mechanism of GroEL-facilitated protein folding.

Adenosine Diphosphate↗
PubMed1994

Morphometry of arterioles and capillaries in hearts of senescent mice.

OBJECTIVE: The aim was to characterise quantitative changes in the coronary arterioles and capillaries with aging in mice. METHODS: Morphometric analysis of the coronary resistance vessels was carried out in 12 "young" mice (63 days) and 11 "old" mice (650 days). RESULTS: Compared to hearts from young mice, those from senescent mice were heavier, contained less water, and differed in several variables characterising terminal vessels. The main changes were a decreased capillary and arteriolar density, increased heterogeneity of capillary spacing, and larger arterioles with thicker walls. CONCLUSIONS: Aging of the murine myocardium is characterised by important changes at the level of the terminal vascular bed, the most prominent being a decrease in capillary and arteriolar density. The decrease in arteriolar density is most prominent in the classes of smallest vessels. All these changes represent an impairment of geometrical conditions for the oxygen supply to the myocardial tissue.

Aging↗
PubMed1994

Assessment of aortic disease using three-dimensional CT angiography.

The recently developed technique of three-dimensional CT angiography (3D-CTA) was applied to 68 patients with aortic disease. These patients were examined using a unique method of data collection: a helical scanner with continuous tube rotation and continuous table feed. The scanner was used in conjunction with administration of dynamic intravenous contrast material to enhance the vascular image. The group of patients included 35 with aortic dissection, 19 with true thoracic aneurysms, and 14 with abdominal aortic aneurysms. Three-dimensional evaluation was achieved in all patients with no complications. Surgical intervention was used in 45 patients with aortic dissections and aortic aneurysms, and 44 of these patients (98%) survived and were discharged. Preoperative 3D-CTA findings were quite similar to intraoperative findings, and were useful in determining operative procedures. Rapid and accurate assessment of aortic disease was achieved by 3D-CTA. Three-dimensional CT angiography can play an important role in the preoperative assessment of aortic dissections and aortic aneurysms leading to successful surgical treatment.

Adult↗
PubMed1994

Immunocytochemical detection of bone marrow-invasive neuroblastoma cells.

We evaluated the utility of an immunocytochemical technique employing the commercially available anti-CD56 monoclonal antibody, NKH 1. The utility and sensitivity of this technique in the detection of invasive neuroblastoma (NB) cells in the bone marrow were compared with those of Wright-Giemsa staining. The correlation coefficient for the percent NB cells detected using Wright-Giemsa staining with the percent NKH 1 immunoreactive cells was 0.78. In the analysis of specificity, this monoclonal antibody showed slight cross-reactivity with normal bone marrow cells, including macrophages, lymphocytes and osteoblasts. In the evaluation of the sensitivity of the NKH 1 immunocytochemical technique, SK-N-DZ and SK-N-SH NB cell lines were added to morphologically normal bone marrow mononuclear cells from patients without NB to the final NB cell line at concentrations of 2%, 1% and 0.1%. NB cells at the final concentration of 0.1% could be detected by the immunocytochemical technique. We conclude that the NKH 1 immunocytochemical staining technique is useful in the detection of metastatic NB cells in bone marrow.

Antibodies, Monoclonal↗
PubMed1994

[Inferior vena caval tumor thrombus in a patient with renal angiomyolipoma associated with tuberous sclerosis].

A 34-year-old woman with tuberous sclerosis presented with an increase of an abdominal mass and intermittent left flank pain on May 20, 1991. Computed tomography showed multiple bilateral renal masses with fatty density areas and a fatty density thrombus in the inferior vena cava, which extended through the right renal vein of the right kidney on ultrasonography. The inferior vena caval thrombus was also demonstrated by magnetic resonance imaging. Since marked deterioration of the right renal function was found on renography, right radical nephrectomy with thrombectomy was performed on July 2. Microscopically all tumors were identical with angiomyolipoma. She was discharged on Jury 20 and had been followed with good renal function at the outpatient clinic for more than 2 years. Follow up CT revealed no interval changes in the left renal masses.

Adult↗