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Arachidonate 12 Lipoxygenase

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Shozo Yamamoto – One of the best experts on this subject based on the ideXlab platform.

  • Hinokitiol, a Selective Inhibitor of the Platelet-Type Isozyme of Arachidonate 12Lipoxygenase
    Biochemical and biophysical research communications, 2000
    Co-Authors: Hiroshi Suzuki, Shozo Yamamoto, Tetsuji Ueda, Ivo Juránek, Takahiro Katoh, Manabu Node, Toshiyuki Suzuki

    Abstract:

    Abstract Hinokitiol (4-isopropyltropolone), a constituent of Japanese cypress, reversibly inhibited platelet-type 12Lipoxygenase with an IC50 of 0.1 μM, and the enzyme activity was almost lost at 1 μM. The compound was much less active with other Lipoxygenase enzymes with higher IC50 values (leukocyte-type 12Lipoxygenase, 50 μM; soybean Lipoxygenase, 17 μM; 15-Lipoxygenase-1, >100 μM; 5-Lipoxygenase, 17 μM). Hinokitiol up to 100 μM had almost no effect on cyclooxygenases-1 and -2. Their structure–activity relationship examined with various tropolone derivatives indicated the requirements of the 2-hydroxyl group and 4-alkyl group for the potent and selective inhibition of platelet-type 12Lipoxygenase.

  • Arachidonate 12Lipoxygenase isozymes.
    Advances in experimental medicine and biology, 1999
    Co-Authors: Shozo Yamamoto, Michihiro Nakamura, Hiroshi Suzuki, Kazunori Ishimura

    Abstract:

    A Lipoxygenase is an enzyme which incorporates one molecule of oxygen into arachidonic acid or other polyunsaturated fatty acids producing hydroperoxy acids with a conjugated diene system. Enzymes oxygenating at the positions 5, 8, 12 and 15 of arachidonic acid and producing the corresponding hydroperoxy eicosatetraenoic acid (HpETE) have been isolated from mammalian tissues (Figure 1). All enzymes except for the 8-Lipoxygenase have been highly purified, and their cDNAs and genomic DNAs have been already cloned (1,2).

  • platelet type Arachidonate 12 Lipoxygenase in mouse gastrointestinal tract
    Acta Histochemica Et Cytochemica, 1998
    Co-Authors: Michihiro Nakamura, Shozo Yamamoto, Kazunori Ishimura

    Abstract:

    12Lipoxygenase enzyme oxygenates the position 12 of arachidonic acid, and produces 12S-hydroperoxy-arachidonic acid. When mouse gastrointestinal tract was immunostained with an antiserum against human platelet 12Lipoxygenase and examined by light microscopy, positively-stained cells were found in the epithelium of stomach and small and large intestines. Electron microscopic immunohistochemistry revealed that the positively-stained cells were open-type enteroendocrine cells. The endocrine cells had many granules of heterogeneous sizes, forms and internal structures, and most of the granules had electron lucent area. 12Lipoxygenase was localized in the cytoplasm, but not in the nucleus, plasma membranes and other subcellular organelles. Double immunostaining revealed that all 12Lipoxygenasepositive cells contained serotonin. With an antiserum against 12Lipoxygenase isozyme of porcine leukocytes, no positively-stained cells were observed in gastrointestinal epithelium.

Tanihiro Yoshimoto – One of the best experts on this subject based on the ideXlab platform.

  • expression of Arachidonate 12 Lipoxygenase in rat tissues a possible role in glucagon secretion
    Journal of Histochemistry and Cytochemistry, 2000
    Co-Authors: Hiroo Kawajiri, Tanihiro Yoshimoto, Daming Zhuang, Na Qiao, Miyuki Yamamoto, Shoichi Iseki, Kazuyuki Hamaguchi

    Abstract:

    There are three isoforms of Arachidonate 12Lipoxygenase in mammals: platelet, leukocyte, and epidermal types. We found in this study that the leukocyte-type enzyme was present in rat pineal gland, lung, spleen, aorta, adrenal gland, spinal cord, and pancreas, as assessed by RT-PCR. Immunohistochemical analysis showed that the enzyme was localized in macrophages in lung and spleen, alpha-cells of pancreatic islet, zona glomerulosa cells of adrenal cortex, and neuronal cells of spinal cord and superior cervical ganglion. The presence of the 12Lipoxygenase in pancreatic alpha-cells was confirmed by glucagon staining in a consecutive section. We overexpressed the leukocyte-type 12Lipoxygenase cDNA in a glucagon-secreting alphaTC clone 6 cell line that had been established from a transgenic mouse. Glucagon secretion was stimulated by approximately twofold in the 12Lipoxygenase-expressing cells compared to the mock-transfected and original cells. The results suggest that the 12Lipoxygenase of the leukocyte type augments glucagon secretion from pancreatic islets.

  • Expression of Arachidonate 12Lipoxygenase in Rat Tissues: A Possible Role in Glucagon Secretion
    The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society, 2000
    Co-Authors: Hiroo Kawajiri, Tanihiro Yoshimoto, Daming Zhuang, Na Qiao, Miyuki Yamamoto, Shoichi Iseki, Kazuyuki Hamaguchi

    Abstract:

    SUMMARY There are three isoforms of Arachidonate 12Lipoxygenase in mammals: platelet, leukocyte, and epidermal types. We found in this study that the leukocyte-type enzyme was present in rat pineal gland, lung, spleen, aorta, adrenal gland, spinal cord, and pancreas, as assessed by RT-PCR. Immunohistochemical analysis showed that the enzyme was localized in macrophages in lung and spleen, a -cells of pancreatic islet, zona glomerulosa cells of adrenal cortex, and neuronal cells of spinal cord and superior cervical ganglion. The presence of the 12Lipoxygenase in pancreatic a -cells was confirmed by glucagon staining in a consecutive section. We overexpressed the leukocyte-type 12Lipoxygenase cDNA in a glucagon-secreting a TC clone 6 cell line that had been established from a transgenic mouse. Glucagon secretion was stimulated by approximately twofold in the 12Lipoxygenase-expressing cells compared to the mock-transfected and original cells. The results suggest that the 12Lipoxygenase of the leukocyte type augments glucagon secretion from pancreatic islets. (J Histochem Cytochem 48:1411‐1419, 2000)

  • Decreased activity of Arachidonate 12Lipoxygenase in platelets of Japanese patients with non-insulin-dependent diabetes mellitus.
    Metabolism: clinical and experimental, 1998
    Co-Authors: Toshio Tohjima, Michihiro Nakamura, Naoko Honda, Kentaro Mochizuki, Junichiro Kinoshita, Kenji Watanabe, Tomoyuki Arisaka, Ryuzo Kawamori, Yuko Kurahashi, Tanihiro Yoshimoto

    Abstract:

    Abstract To study the metabolism of the platelet 12Lipoxygenase pathway in diabetes, we evaluated the correlation between the activity and amount of Arachidonate 12Lipoxygenase in the platelets of patients with non—insulin-dependent-diabetes mellitus (NIDDM). There were four parts in this investigation: (1) examination of abnormalities in platelet 12Lipoxygenase in patients with NIDDM recruited from the Hospital of Juntendo University School of Medicine; (2) comparison of 12Lipoxygenase in the platelets of non-obese NIDDM patients without angiopathy versus normal subjects matched for age, sex, and body mass index (BMI); (3) evaluation of gender differences; and (4) assessment of the potential influence of glycemic control. The activity of 12Lipoxygenase was assayed by incubation of [1-14C]arachidonic acid with the platelet cytosol. The reaction mixture was extracted and separated by thin-layer chromatography, and the radioactive end products were detected. The activity of 12Lipoxygenase in the platelets of patients with NIDDM was significantly less than in normal subjects (P

Michihiro Nakamura – One of the best experts on this subject based on the ideXlab platform.

  • Arachidonate 12Lipoxygenase isozymes.
    Advances in experimental medicine and biology, 1999
    Co-Authors: Shozo Yamamoto, Michihiro Nakamura, Hiroshi Suzuki, Kazunori Ishimura

    Abstract:

    A Lipoxygenase is an enzyme which incorporates one molecule of oxygen into arachidonic acid or other polyunsaturated fatty acids producing hydroperoxy acids with a conjugated diene system. Enzymes oxygenating at the positions 5, 8, 12 and 15 of arachidonic acid and producing the corresponding hydroperoxy eicosatetraenoic acid (HpETE) have been isolated from mammalian tissues (Figure 1). All enzymes except for the 8-Lipoxygenase have been highly purified, and their cDNAs and genomic DNAs have been already cloned (1,2).

  • platelet type Arachidonate 12 Lipoxygenase in mouse gastrointestinal tract
    Acta Histochemica Et Cytochemica, 1998
    Co-Authors: Michihiro Nakamura, Shozo Yamamoto, Kazunori Ishimura

    Abstract:

    12Lipoxygenase enzyme oxygenates the position 12 of arachidonic acid, and produces 12S-hydroperoxy-arachidonic acid. When mouse gastrointestinal tract was immunostained with an antiserum against human platelet 12Lipoxygenase and examined by light microscopy, positively-stained cells were found in the epithelium of stomach and small and large intestines. Electron microscopic immunohistochemistry revealed that the positively-stained cells were open-type enteroendocrine cells. The endocrine cells had many granules of heterogeneous sizes, forms and internal structures, and most of the granules had electron lucent area. 12Lipoxygenase was localized in the cytoplasm, but not in the nucleus, plasma membranes and other subcellular organelles. Double immunostaining revealed that all 12Lipoxygenasepositive cells contained serotonin. With an antiserum against 12Lipoxygenase isozyme of porcine leukocytes, no positively-stained cells were observed in gastrointestinal epithelium.

  • Decreased activity of Arachidonate 12Lipoxygenase in platelets of Japanese patients with non-insulin-dependent diabetes mellitus.
    Metabolism: clinical and experimental, 1998
    Co-Authors: Toshio Tohjima, Michihiro Nakamura, Naoko Honda, Kentaro Mochizuki, Junichiro Kinoshita, Kenji Watanabe, Tomoyuki Arisaka, Ryuzo Kawamori, Yuko Kurahashi, Tanihiro Yoshimoto

    Abstract:

    Abstract To study the metabolism of the platelet 12Lipoxygenase pathway in diabetes, we evaluated the correlation between the activity and amount of Arachidonate 12Lipoxygenase in the platelets of patients with non—insulin-dependent-diabetes mellitus (NIDDM). There were four parts in this investigation: (1) examination of abnormalities in platelet 12Lipoxygenase in patients with NIDDM recruited from the Hospital of Juntendo University School of Medicine; (2) comparison of 12Lipoxygenase in the platelets of non-obese NIDDM patients without angiopathy versus normal subjects matched for age, sex, and body mass index (BMI); (3) evaluation of gender differences; and (4) assessment of the potential influence of glycemic control. The activity of 12Lipoxygenase was assayed by incubation of [1-14C]arachidonic acid with the platelet cytosol. The reaction mixture was extracted and separated by thin-layer chromatography, and the radioactive end products were detected. The activity of 12Lipoxygenase in the platelets of patients with NIDDM was significantly less than in normal subjects (P