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K Hara

Publications and source records attributed to K Hara.

At least 19 recordsLinked to original sources
PubMed1992

Insulin-dependent formation of a complex containing an 85-kDa subunit of phosphatidylinositol 3-kinase and tyrosine-phosphorylated insulin receptor substrate 1.

Monoclonal antibodies raised against the 85-kDa subunit (p85) of bovine phosphatidylinositol (PI) 3-kinase were found to recognize uncomplexed p85 or p85 in the active PI 3-kinase. Immunoprecipitation studies of Chinese hamster ovary cells, which overexpress the human insulin receptor when treated with insulin, showed increased amounts of p85 and PI 3-kinase activity immunoprecipitable with monoclonal anti-p85 antibody and no increase in the tyrosine phosphorylation of p85. Insulin also induced an association of p85 with the tyrosine-phosphorylated insulin receptor substrate 1 (IRS-1) and other phosphorylated proteins ranging in size from 100 to 170 kDa but not with the activated insulin receptor. In vitro reconstitution studies were used to show p85 in the active PI 3-kinase associated with the tyrosine-phosphorylated IRS-1 but not with the activated insulin receptor. Competition studies using synthetic phosphopeptides corresponding to potential tyrosine phosphorylation sites of IRS-1 revealed that phosphopeptides containing YMXM motifs inhibited this association with different potencies, whereas nonphosphorylated analogues and a phosphopeptide containing the EYYE motif had no effect. Src homology region 2 domains of p85 expressed as glutathione S-transferase fusion proteins also bound to tyrosine-phosphorylated IRS-1. These results suggest that insulin causes the association of PI 3-kinase with IRS-1 via phosphorylated YMXM motifs of IRS-1 and Src homology region 2 domains of p85.

Amino Acid Sequence↗
PubMed1992

Sequential activation of MAP kinase activator, MAP kinases, and S6 peptide kinase in intact rat liver following insulin injection.

An insulin-stimulated phosphorylation cascade was examined in rat liver after insulin injection via a portal vein by the use of immune complex kinase assays specific to the mitogen-activated protein (MAP) kinase and S6 kinase II homologue (rsk) kinase. We have prepared an antibody against the peptide consisting of a carboxyl-terminal portion of the extracellular signal-regulated kinase 1 (alpha C92), one of the MAP kinases, and an antibody against the peptide consisting of the carboxyl terminus of the mouse S6 kinase II homologue (alpha rsk(m)C). In alpha C92 immune complex assay, maximal activation of rat liver MAP kinases (approximately 4.3-fold) were observed 4.5 min after insulin injection. We also observed an insulin-stimulated MAP kinase activity (approximately 3-fold) in liver extracts from insulin-treated rat in fractions eluted from phenyl-Sepharose with 30-50% ethylene glycol. Kinase assay in myelin basic protein (MBP)-containing gel after sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by denaturation with 6 M guanidine HCl, and renaturation revealed that insulin injection stimulated the kinase activity of the 42- and 44-kDa proteins, which corresponded to the two distinct MAP kinases. In alpha rsk(m)C immune complex assay, maximal stimulation (approximately 5-fold) of the S6 peptide (Arg-Arg-Leu-Ser-Ser-Leu-Arg-Ala) kinase activity was observed 7.5 min after insulin injection. In addition, MAP kinases purified from insulin-treated rat liver were able to activate S6 peptide kinase activity in vitro in alpha rsk(m)C immunoprecipitates from untreated rat liver, accompanied by the appearance of several phosphorylated bands including a major band at 88 kDa. We also examined whether insulin injection stimulates the MAP kinase activator (Ahn, N. G., Seger, R., Bratlien, R. L., Diltz, C. D., Tonks, N. K., and Krebs, E. G. (1991) J. Biol. Chem. 266, 4220-4227) in rat liver. Using recombinant Xenopus MAP kinase, fractions of Q-Sepharose eluted early in the NaCl gradient were found to have MAP kinase activator activity accompanied by the phosphorylation of 42-kDa recombinant Xenopus MAP kinase. From these data, we demonstrate three tiers of a cascade composed of the MAP kinase activator, MAP kinases, and an S6 peptide kinase activity in rat liver under physiological conditions in the intact animal.

Adenosine Triphosphate↗
PubMed1992

Autocrine and paracrine effects of endothelium-derived relaxing factor on intracellular Ca2+ of endothelial cells and vascular smooth muscle cells. Identification by two-dimensional image analysis in coculture.

To elucidate the effects of endothelium-derived relaxing factor (EDRF) released from vascular endothelial cells (ECs) on handling of intracellular calcium ion (Ca2+i) in ECs themselves and vascular smooth muscle cells (VSMCs), we measured the Ca2+i by two-dimensional digital image analysis of fura-2-loaded ECs and VSMCs in tissue culture. In isoculture of one cell type, adenosine triphosphate (ATP, 1 microM) transiently increased the Ca2+i of both ECs and VSMCs. High-K+ depolarization or angiotensin II also elevated the Ca2+i of VSMCs, whereas neither stimulants changed the Ca2+i of ECs. In coculture of ECs with VSMCs, the same dose of ATP rapidly increased the Ca2+i of ECs and then transiently decreased the Ca2+i of VSMCs to below the resting level. The maximal Ca2+i-modulating effects of ATP on both cell types were reproducible after the second application of ATP. Three kinds of EDRF blockers (L-NG-monomethylarginine, methemoglobin, or methylene blue) potentiated the ATP-induced Ca2+i rise in ECs and attenuated the Ca2+i reduction in VSMCs, suggesting the autocrine and paracrine effects of EDRF on ECs and VSMCs, respectively. However, neither indomethacin, superoxide dismutase, nor neutralizing monoclonal antibody to endothelin-1 altered the second responses. Thus, two-dimensional Ca2+i image analysis of ECs and VSMCs in coculture enabled direct visualization of the EDRF actions in ECs and VSMCs and their modifications.

Adenosine Triphosphate↗
PubMed1992

In vitro association of phosphatidylinositol 3-kinase activity with the activated insulin receptor tyrosine kinase.

We previously have shown that insulin treatment of cells greatly increases the activity of phosphatidylinositol (PI) 3-kinase in immunoprecipitates made with an antibody to phosphotyrosine. However, the association of PI 3-kinase activity with the activated insulin receptor is not significant under these conditions. In the present study, we have attempted to reconstitute the association of PI 3-kinase activity with the activated insulin receptor in vitro. PI 3-kinase activity does indeed associate with the autophosphorylated insulin receptor in our in vitro system. The autophosphorylation of the insulin receptor and/or its associated conformational change appear to be necessary for the association of PI 3-kinase activity with the receptor, since kinase negative receptor failed to bind PI 3-kinase activity. After binding, PI 3-kinase or its associated protein seems to be released from the activated receptor after the completion of its tyrosine phosphorylation by the receptor. Tyr960 in the juxtamembrane region of the insulin receptor beta-subunit seems to be involved in the association of PI 3-kinase activity with the receptor, but not C terminus region of the beta-subunit including two tyrosine autophosphorylation sites (Tyr1316 and Tyr1322). The in vitro assay system for the association of PI 3-kinase activity with the insulin receptor can be utilized to study the mechanism of interaction of these molecules and will be an useful method to detect other associated molecules with the insulin receptor.

Animals↗
PubMed1992

Prolyl endopeptidase purified from granulomatous inflammation in mice.

Activity of prolyl endopeptidase (EC 3.4.21.26) which hydrolyses the Pro7-Phe8 bond in angiotensin II has been found to elevate in experimentally produced granulomatous inflammation in liver and skin. We purified the enzyme 1,536-fold by 6 steps from murine hepatic granulomas. The purified enzyme has a molecular weight of 79 kDa and physicochemical properties equivalent to those previously reported for prolyl endopeptidase purified from other sources. By HPLC analysis, the cleavage of Phe8-Leu10 and Phe8 from angiotensin I and II, respectively, was detected and quantified. Monospecific IgG was prepared from serum of rabbits injected with purified enzyme. Concentration of the enzyme was immunohistochemically detected in cells which form granulomatous organization, but not in inflammatory cells surrounding the foci. The antibody, however, cross reacted with the enzyme in adjacent liver cells and weakly stained their cytoplasm. The findings indicate that this enzyme, in addition to angiotensin converting enzyme, may serve as a useful biochemical marker for granulomatous tissue reactions.

Angiotensin I↗
PubMed1992

G test, a new direct method for diagnosis of Candida infection: comparison with assays for beta-glucan and mannan antigen in a rabbit model of systemic candidiasis.

An indirect method to measure beta-glucan, a major structural component of yeast cell walls, is available, but has the disadvantage of requiring the combined use of two assays. Recent reports describe the fungal index, which measures the difference between the conventional limulus test, in which factors C and G react with endotoxin and beta-glucan, and a new endotoxin-specific test, in which only factor C reacts with endotoxin. The G test was developed as a direct method to measure beta-glucan, and contains only factor G reacting with beta-glucan alone. In this study, the G test was examined in sera of rabbits with experimental systemic candidiasis, and compared with the fungal index and mannan assay. The G test showed positive in all rabbits with systemic candidiasis faster and with higher titers than with the fungal index. Three rabbits with fulminant systemic candidiasis showed higher levels of reactivity with the G test and the fungal index than two rabbits with mild reactions. Mannan was positive by at least one serum in four of five rabbits by the latex agglutination test, and there was a good correlation between these assays. The G test is a good serodiagnostic method for the detection of candidiasis.

Animals↗
PubMed1992

Myasthenia gravis with thymoma associated with occult thyroid carcinoma.

We report herein a case of myasthenia gravis associated with thymoma and occult thyroid carcinoma with metastasis to a cervical lymph node, which was treated in two stages by a total thymectomy and radical dissection of the bilateral neck after a total thyroidectomy. A 48 year old woman was admitted with right blepharoptosis and hypodynamia of the proximal muscles. After various examinations, a diagnosis of myasthenia gravis was made. The association of thymoma was clarified upon CT scanning and a total thymectomy performed. However, after surgery, swelling of the cervical lymph nodes became apparent and a biopsy revealed metastasis of thyroid carcinoma in the lymph nodes. A diagnosis of occult thyroid carcinoma with metastasis to a cervical lymph node was subsequently made and a total thyroidectomy and radical dissection of the bilateral neck performed 37 days after the total thymectomy. The patient's postoperative course was uneventful and for the time being, no recurrence is expected. It is considered better to perform two-stage operations for easier and safer postoperative management when myasthenia gravis associated with occult thyroid carcinoma is treated, although it depends on the development of thyroid carcinoma being occult.

Female↗
PubMed1992

Studies on the hepatotoxicity induced by bis (tributyltin) oxide.

The toxic effects of bis (tributyltin) oxide (TBTO) on the rat liver were studied with an electron microscope and the accumulation sites of tin were determined with an X-ray microanalyzer. The activities of serum enzymes and the concentration of serum bilirubin were also analyzed. Male Wistar rats received an intramuscular injection of 0.5 ml/kg of TBTO. Marked swelling of the mitochondria appeared in the hepatocytes 4 h after injection of TBTO. Cytoplasmic vacuoles, which contained degenerated mitochondria, gradually increased in number in these hepatocytes. This in turn may have caused a decrease in the volume of hepatic cell cords and an enlargement of sinusoids in the entire hepatic lobule. However, fine structures of intrahepatic bile ducts were not altered. By X-ray microanalysis, tin peaks were preferentially obtained from swollen mitochondria of the hepatocytes. By polarographic analysis of the respiratory responses of mitochondria, it was demonstrated that rates of state 4 respiration and respiratory control ratio were significantly disturbed in TBTO-treated rats in comparison with those of controls. The activities of AST (aspartate aminotransferase) and ALT (alanine aminotransferase) were significantly increased after TBTO treatment, but those of ALP (alkaline phosphatase), LAP (leucine aminopeptidase) and total bilirubin were not changed. These results indicated that parenterally administered TBTO accumulated in the liver cell mitochondria and disturbed oxidative phosphorylation. Mitochondrial dysfunction might induce severe damage of the hepatocytes. Four days after injection of TBTO, hepatic structures and chemical indices were almost restored by the regeneration of hepatocytes.

Alanine Transaminase↗
PubMed1992

Development and characterization of Porphyromonas gingivalis-specific rat T-cell clones.

Porphyromonas gingivalis has been implicated as a major pathogen in periodontitis. To determine the role of T cells in the regulation of this disease, a method was developed for the generation and characterization of rat T-cell clones with antigen specificity to P. gingivalis whole cells. The clones studied so far demonstrated a T-helper (Th) phenotype W3/13+, W3/25+, OX8- and OX22-. These T-cell clones proliferated in vitro in response to P. gingivalis, but not to other bacteria (Prevotella intermedia, Actinobacillus actinomycetemcomitans, Wolinella recta, Fusobacterium nucleatum, Streptococcus sanguis). Limiting dilution analysis showed W3/25+, OX8- T cells preferentially respond to P. gingivalis, rather than W3/25-, OX8+ T cells. P. gingivalis-reactive W3/25+ T cells belonged to the OX22- population, suggesting that the OX22- T cells may represent memory cells. All clones tested produced interferon gamma, but not interleukin 2. The cloned T-cell F1 significantly enhanced P. gingivalis-specific antibody production (p < 0.03). The availability of these cloned T cells should bring new insight into the mechanism by which T cells regulate oral health and periodontal disease.

Animals↗
PubMed1992

The role of the rat submandibular gland in the excretion of bis (tributyltin) oxide: electron microscopy, X-ray microanalysis and atomic absorption analysis.

The role of the submandibular glands in the excretion of parenterally administered bis (tributyltin) oxide (TBTO) was studied. Fine structural alterations of the submandibular glands were observed with an electron microscope. Accumulation sites of TBTO were determined with an X-ray microanalyzer and tin concentrations in saliva and blood were measured by atomic absorption spectrophotometry.

Animals↗
PubMed1992

Detection of human papillomavirus genome and analysis of expression of c-myc and Ha-ras oncogenes in invasive cervical carcinomas.

Invasive carcinomas of the uterine cervix of 38 patients were examined for the presence of human papillomavirus (HPV) genomes and for the state of the c-myc and Ha-ras oncogenes. A combination of Southern blot hybridization and polymerase chain reaction revealed the presence of the genome of HPV type 16 in 17 tumors (45%), that of HPV type 18 in 3 tumors (8%), and that of unknown types in 16 others (42%), while no viral DNA sequences were detected in 2 tumors. Of the 38 tumors, c-myc amplification was found in only 1 tumor, while there was no Ha-ras amplification. Overexpression of the c-myc gene was observed in 15 (44%) of the 34 tumors analyzed, while there was no overexpression of Ha-ras. Of the 23 squamous cell carcinomas analyzed, relapse-free rates at 24 months were 55% in tumors with c-myc overexpression and 100% in case of tumors with no c-myc overexpression, respectively. The results suggest the possibility that activation of the c-myc oncogene is involved in tumor progression.

Base Sequence↗
PubMed1992

Purification and characterization of cathepsin H from hepatopancreas of carp Cyprinus carpio.

1. Cathepsin H was purified about 5400-fold from hepatopancreas of carp (Cyprinus carpio) by the method involving ammonium sulfate fractionation, and chromatography on S-Sepharose, DEAE-Sephacel, Ultrogel AcA54, Concanavalin A-Sepharose 4B and GPC on Protein-Pak 125. 2. The purified cathepsin H gave a single protein band on analytical-PAGE, but migrated as two bands of 27,000 and 23,000 mol. wt on SDS-PAGE. 3. Cathepsin H had a pH and temperature optimum of 6.5 and 45 degrees C using Arg-MCA as a substrate, respectively, and was activated by sulfhydryl compounds and inhibited by cysteine protease inhibitors and metal compounds having high reactivities at cysteine residue. 4. The carp hepatopancreas cathepsin H immunoreacted with the monospecific antibody against rat liver cathepsin H, and did not react with the antibodies against carp hepatopancreas cathepsins B and L by the method of immunoelectrophoretic blotting.

Animals↗
PubMed1992

Dysplastic nevus syndrome among Japanese. A case study and review of the Japanese literature.

Three Japanese families with dysplastic nevus syndrome (DNS) are reported. Each family had at least two members with multiple dysplastic nevi (DN). Family members with DN or multiple moles had paler skin than average Japanese, usually sunburned, and tanned less than average, whereas members with darker skin almost never had DN. Each of two families had one cutaneous malignant melanoma (CMM) patient associated with multiple DN. Both CMMs were on the leg. In Japanese DNS, skin color and sun sensitivity seem to be closely related to DN. The locations of CMMs associated with DNS were unique: No CMMs were found on acral areas where they most frequently occur in Japanese.

Adult↗
PubMed1992

Acrosyringeal adenomatosis (eccrine syringofibroadenoma of Mascaro). A case report and review of the literature.

The case of a 63-year-old man with acrosyringeal adenomatosis (eccrine syringofibroadenoma of Mascaro) is reported. Asymptomatic papular lesions had appeared on the dorsum of both of his feet 30 years earlier, then extended gradually and symmetrically to his hands, arms, legs, trunk, and auriculae. Although his hair, teeth, and nails were normal, he had glaucoma, chronic sinusitis, chronic otitis media, chronic pancreatitis, and gastrointestinal polyposis. No similar symptoms were found in the family history. Histopathologically, proliferations of pale epithelial cells extended from acrosyringia into the dermis, forming interconnected epithelial cords, within some of which were ductal structures. A syringoma and syringoma-like structures were closely associated with these lesions. Enzyme-histochemical, immunohistochemical, and ultrastructural studies supported the concept that this case represents a benign tumor derived from the acrosyringium, which is different from eccrine poroma. Acrosyringeal adenomatosis seems to be a more appropriate name for such a lesion than does eccrine syringofibroadenoma (Mascaro).

Adenoma↗