Angel Ramirez | Universidad Autónoma Metropolitana-Iztapalapa (original) (raw)
Address: Mexico City, Mexico City, Mexico
less
Uploads
Papers by Angel Ramirez
Proceedings of The National Academy of Sciences, 2000
Abbreviations: IGF-1, insulin-like growth factor 1; IGF-1r, insulin-like growth factor-1 receptor... more Abbreviations: IGF-1, insulin-like growth factor 1; IGF-1r, insulin-like growth factor-1 receptor; MUP, major urinary protein; BK5, bovine keratin 5; IGFBP-3, IGF binding protein 3; PIN, prostatic intraepithelial neoplasia; PI3, phosphatidylinositol 3. † To whom reprint requests should be addressed.
Transgenic mice overexpressing insulin-like growth factor-1 (IGF-1) in the basal layer of skin ep... more Transgenic mice overexpressing insulin-like growth factor-1 (IGF-1) in the basal layer of skin epidermis were generated using the bovine keratin 5 promoter (BK5). Neonatal transgenic mice were slightly smaller at birth and exhibited early ear unfolding, wrinkled and thickened skin, and slightly enlarged ears compared with nontransgenic littermates. Morphological evaluation of the skin revealed that persistent overexpression of IGF-1 in the basal layer of the epidermis resulted in epidermal hyperplasia, hyperkeratosis, and an increased labeling index that persisted in adult mice. Phenotypic changes observed in skin were associated with transgene expression in the basal layer of the epidermis and activation of the IGF-1 receptor. Squamous papillomas (some of which converted to carcinomas) developed in a significant proportion (ϳ50%) of older BK5.IGF-1 mice. Treatment of BK5.IGF-1 transgenic mice with multiple topical applications of the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate, in the absence of tumor initiation led to the development of additional skin papillomas. Furthermore, treatment of BK5.IGF-1 transgenic mice with an initiating dose of 7,12-dimethylbenz[a]anthracene only led to the formation of additional papillomas in the absence of promotion. In two-stage carcinogenesis experiments, BK5.IGF-1 transgenic mice developed 7-fold more papillomas than nontransgenic littermates. Phosphatidylinositol-3-kinase and protein kinase B (Akt) activities were elevated (3-4-fold), and mitogen-activated protein kinase activity was elevated ϳ1.7-fold in the epidermis of transgenic mice compared with nontransgenic mice. In addition, UV light-induced epidermal apoptosis was significantly suppressed in BK5.IGF-1 transgenic mice. These data suggest that persistent activation of IGF-1 receptor signaling pathways in basal epithelial cells leads to spontaneous tumor promotion and that up-regulation of both mitogenic and cell survival signaling pathways may play an important role in the action of IGF-1 in this model system.
Reversed-phase high performance liquid chromatography (RP-HPLC) method with UV/VIS detection was ... more Reversed-phase high performance liquid chromatography (RP-HPLC) method with UV/VIS detection was established for the separation and identification of flavonoids in the methanolic and ethanolic extracts of coriander (Coriandrum sativum L.) seeds. Separation was achieved using a column RP-C 18 VARIAN Pursuit XPs with dimensions 250 x 4.6mm using a mobile phase of formic acid and acetonitrile gradient. Rutin, quercetin, chlorogenic acid and caffeic acid were identified and quantified in the multi-component methanolic and ethanolic extracts by comparing with the respective standards using the method of RP-HPLC. The methanolic extract produced sharp peaks in comparison to the ethanolic extract. Chlorogenic acid was predominant in methanolic extract followed by rutin, caffeic acid and quercetin while rutin was predominant in ethanolic extract followed by chlorogenic acid, caffeic acid and quercetin. Though similar compounds were identified in both the extracts, the concentration and purity of the compounds were superior in the methanolic extract as compared with that of the ethanolic extract. Besides, chromatograms of ethanolic extracts had peak tailing which indicates that the bio-active principles are extracted better in methanol.
Proceedings of The National Academy of Sciences, 2000
Abbreviations: IGF-1, insulin-like growth factor 1; IGF-1r, insulin-like growth factor-1 receptor... more Abbreviations: IGF-1, insulin-like growth factor 1; IGF-1r, insulin-like growth factor-1 receptor; MUP, major urinary protein; BK5, bovine keratin 5; IGFBP-3, IGF binding protein 3; PIN, prostatic intraepithelial neoplasia; PI3, phosphatidylinositol 3. † To whom reprint requests should be addressed.
Transgenic mice overexpressing insulin-like growth factor-1 (IGF-1) in the basal layer of skin ep... more Transgenic mice overexpressing insulin-like growth factor-1 (IGF-1) in the basal layer of skin epidermis were generated using the bovine keratin 5 promoter (BK5). Neonatal transgenic mice were slightly smaller at birth and exhibited early ear unfolding, wrinkled and thickened skin, and slightly enlarged ears compared with nontransgenic littermates. Morphological evaluation of the skin revealed that persistent overexpression of IGF-1 in the basal layer of the epidermis resulted in epidermal hyperplasia, hyperkeratosis, and an increased labeling index that persisted in adult mice. Phenotypic changes observed in skin were associated with transgene expression in the basal layer of the epidermis and activation of the IGF-1 receptor. Squamous papillomas (some of which converted to carcinomas) developed in a significant proportion (ϳ50%) of older BK5.IGF-1 mice. Treatment of BK5.IGF-1 transgenic mice with multiple topical applications of the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate, in the absence of tumor initiation led to the development of additional skin papillomas. Furthermore, treatment of BK5.IGF-1 transgenic mice with an initiating dose of 7,12-dimethylbenz[a]anthracene only led to the formation of additional papillomas in the absence of promotion. In two-stage carcinogenesis experiments, BK5.IGF-1 transgenic mice developed 7-fold more papillomas than nontransgenic littermates. Phosphatidylinositol-3-kinase and protein kinase B (Akt) activities were elevated (3-4-fold), and mitogen-activated protein kinase activity was elevated ϳ1.7-fold in the epidermis of transgenic mice compared with nontransgenic mice. In addition, UV light-induced epidermal apoptosis was significantly suppressed in BK5.IGF-1 transgenic mice. These data suggest that persistent activation of IGF-1 receptor signaling pathways in basal epithelial cells leads to spontaneous tumor promotion and that up-regulation of both mitogenic and cell survival signaling pathways may play an important role in the action of IGF-1 in this model system.
Reversed-phase high performance liquid chromatography (RP-HPLC) method with UV/VIS detection was ... more Reversed-phase high performance liquid chromatography (RP-HPLC) method with UV/VIS detection was established for the separation and identification of flavonoids in the methanolic and ethanolic extracts of coriander (Coriandrum sativum L.) seeds. Separation was achieved using a column RP-C 18 VARIAN Pursuit XPs with dimensions 250 x 4.6mm using a mobile phase of formic acid and acetonitrile gradient. Rutin, quercetin, chlorogenic acid and caffeic acid were identified and quantified in the multi-component methanolic and ethanolic extracts by comparing with the respective standards using the method of RP-HPLC. The methanolic extract produced sharp peaks in comparison to the ethanolic extract. Chlorogenic acid was predominant in methanolic extract followed by rutin, caffeic acid and quercetin while rutin was predominant in ethanolic extract followed by chlorogenic acid, caffeic acid and quercetin. Though similar compounds were identified in both the extracts, the concentration and purity of the compounds were superior in the methanolic extract as compared with that of the ethanolic extract. Besides, chromatograms of ethanolic extracts had peak tailing which indicates that the bio-active principles are extracted better in methanol.