Freddy Gonzalez-Mujica | Universidad Central de Venezuela (original) (raw)
Papers by Freddy Gonzalez-Mujica
Revista de la Facultad de Medicina, 2002
European Journal of Histochemistry, 2004
During the Wilhelm Bernhard Workshop, the 18th International Workshop on the Cell Nucleus, held i... more During the Wilhelm Bernhard Workshop, the 18th International Workshop on the Cell Nucleus, held in Pavia last September, the idea was born to ask some of the participants for sending a paper for a special issue on the cell nucleus of the European Journal of Histochemistry, to celebrate the 50th anniversary of its foundation. In the following pages, the contributions of several scientists working in this field have been collected, each article having a special look and attention to a particular aspect of nuclear biology. As it was pointed out during the opening lecture of the Workshop, we had several anniversaries in 2003, which are concerned with the cell nucleus. The 50 years of the double helix paper have been celebrated all over the world, but two others are worth mentioning: the paper by Cogliati and Gautier on the synthesis of osmium ammine for the specific staining of DNA at electron microscopy was published exactly 30 years ago, and 25 years ago Dr. Wilhelm Bernhard died. Ber...
Biochemical Journal, 1973
1. The effects of the inclusion of thioacetamide in the diet on the properties of rat liver nucle... more 1. The effects of the inclusion of thioacetamide in the diet on the properties of rat liver nuclei were studied both in adolescent rats, in which the parenchymal cells contain diploid nuclei, and in young adult rats, with a high proportion of tetraploid nuclei. 2. These investigations included a survey of the sedimentation properties of the nuclei, the nuclear volumes, content of DNA, RNA and protein, the incorporation in vivo of [3H]thymidine into DNA and [14C]orotate into RNA, and measurements of the activity of RNA polymerase and ribonuclease. These studies were conducted on nuclei fractionated by zonal centrifugation. 3. In both groups of animals, exposure to thioacetamide produced large numbers of nuclei that were abnormal in their chemical composition and enzymic activity. The changes were complex as regards both the types of nuclei that were affected and in their variation with time. 4. In adolescent rats two waves of synthesis of DNA and RNA were observed, one at 3 days and ...
Biochemical Society Transactions, 1994
Biochemical Society Transactions, 1994
Biochemical Society Transactions, 1994
Archivos Venezolanos de Farmacologia y Terapeutica
The Bauhinia megalandra leaves aqueous extract, has been commonly used in Venezuela for the empir... more The Bauhinia megalandra leaves aqueous extract, has been commonly used in Venezuela for the empiric treatment of diabetes mellitus. In this work, the effect of B. megalandra aqueous extract on hepatic epinephrine or dibutyril cAMP stimulated glycogenolysis, was studied. The oral administration of the plant extract to feed rats decreased the epinephrineraised glycemia in a statystical significant way. Furthermore, liver slices from feed rats, incubated in the presence of B. megalandra extract, released less glucose in response to epinephrine or dibutiryl cAMP than controls. This results shows a decrease in the hepatic glycogenolysis due to the effect of B. megalandra leaves aqueous extract probably as result of the inhibition of the glucose-6-phosphatase enzyme.
Investigación clínica, 2008
Nuclear envelope (NE) and microsomal glucosa-6-phosphatase (G-6-Pase) activities were compared. I... more Nuclear envelope (NE) and microsomal glucosa-6-phosphatase (G-6-Pase) activities were compared. Intact microsomes were unable to hydrolyze mannose-6-phosphate (M-6-P), on the other hand, intact NE hydrolyzes this substrate. Galactose-6-phosphate showed to be a good substrate for both NE and microsomal enzymes, with similar latency to that obtained with M-6-P using microsomes. In consequence, this substrate was used to measure the NE integrity. The kinetic parameters (Kii and Kis) of the intact NE G-6-Pase for the phlorizin inhibition using glucose-6-phosphate (G-6-P) and M-6-P as substrates, were very similar. The NE T1 transporter was more sensitive to amiloride than the microsomal T1. The microsomal system was more sensitive to N-ethylmalemide (NEM) than the NE and the latter was insensitive to anion transport inhibitors DIDS and SITS, which strongly affect the microsomal enzyme. The above results allowed to postulate the presence of a hexose-6-phosphate transporter in the NE whic...
Vitae: Academia Biomédica Digital, 2010
Page 1. Julio-Septiembre N°43 ISSN 1317-987X Artículos Actividad Antihiperglicemiante de Bauhinia... more Page 1. Julio-Septiembre N°43 ISSN 1317-987X Artículos Actividad Antihiperglicemiante de Bauhinia megalandra.(Revisión) Introducción Efectos de B. megalandra sobre la neoglucogénesis y la G-6-Pasa Efectos de B. megalandra ...
Rev. Fac. Cienc. Vet, 2007
... José D. Pradere*,1, Ana Z. Ruiz E.*, Freddy González M.** y Alejandro Correa*** ... Ligamento... more ... José D. Pradere*,1, Ana Z. Ruiz E.*, Freddy González M.** y Alejandro Correa*** ... Ligamento ancho (la), riñón derecho (rd), arteria aorta (aa), uréter (u), arteria ovárica (ao), ovario derecho (od), ovario izquierdo (oi) ... Szabuniewicz, M.; Sánchez, L.; Sosa, A.; Gómez, M. 1977. ...
scielo.org.ve
How to cite Complete issue More information about this article Journal's homepage in redalyc.org ... more How to cite Complete issue More information about this article Journal's homepage in redalyc.org Scientific Information System Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Non-profit academic project, developed under the open access initiative
Rev. Fac. Med.( …, 1989
Base de dados : LILACS. Pesquisa : 86786 [Identificador único]. Referências encontradas : 1 [refi... more Base de dados : LILACS. Pesquisa : 86786 [Identificador único]. Referências encontradas : 1 [refinar]. Mostrando: 1 .. 1 no formato [Detalhado]. página 1 de 1, 1 / 1, LILACS, seleciona. para imprimir. Fotocópia. experimental, Documentos relacionados. Id: 86786. ...
Invest. clín, 1988
Base de dados : LILACS. Pesquisa : 78954 [Identificador único]. Referências encontradas : 1 [refi... more Base de dados : LILACS. Pesquisa : 78954 [Identificador único]. Referências encontradas : 1 [refinar]. Mostrando: 1 .. 1 no formato [Detalhado]. página 1 de 1, 1 / 1, LILACS, seleciona. para imprimir. Fotocópia. experimental, Documentos relacionados. Id: 78954. ...
Acta Diabetologica Latina, 1974
Page 1. DEPARTAMENTO DE CIENCIAS FISIOLOGICAS, FACULTAD DE MEDICINA UNIVERSIDAD CENTRAL DE VENEZU... more Page 1. DEPARTAMENTO DE CIENCIAS FISIOLOGICAS, FACULTAD DE MEDICINA UNIVERSIDAD CENTRAL DE VENEZUELA, CARACAS EFFECTS OF INSULIN AND GLUCOSE ON SUBCELLULAR FRACTIONS FROM RAT ADIPOSE TISSUE ...
Acta científica venezolana, 1983
Acta científica venezolana, 1978
Phytochemistry, Jan 6, 2017
Five previously undescribed triterpene saponins, billiosides A-E, and a known analogue, were isol... more Five previously undescribed triterpene saponins, billiosides A-E, and a known analogue, were isolated from the seeds of Billia rosea (Planch. & Linden) C. Ulloa & P. Jørg. Their structures were elucidated on the basis of extensive 1D and 2D NMR experiments ((1)H, (13)C, DEPT, COSY, TOCSY, NOESY, ROESY, HSQC, and HMBC) and mass spectrometry as (3β,21β,22α)-3-[(2-O-β-D-glucopyranosyl-O-[α-L-arabinopyranosyl-(1 → 4)]-β-D-glucopyranosyl)oxy]-21-[((2E,6S)-2,6-dimethyl-6-hydroxyocta-2,7-dienoyl)oxy]-22-(acetyloxy)-24-hydroxyolean-12-en-28-oic acid, (3β,21β,22α)-3-[(2-O-β-D-galactopyranosyl-β-D-glucopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O-α-L-arabinopyranosyl-(1 → 4)-β-D-glucopyranoside, (3β,21β,22α)-3-[(2-O-β-D-galactopyranosyl-O-[α-L-arabinopyranosyl-(1 → 4)]-β-D-xylopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O-β-D-glucopyranoside, (3β,21β,22α)-3-[(2-O-β-D-galactopyranosyl-O-[α-L-arabinopyranosyl-(1 → 4)]-β-D-glucopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O-β-D-gluco...
Phytotherapy Research, 2005
From the methanol extract of Bauhinia megalandra fresh leaves, eight flavonoids were isolated and... more From the methanol extract of Bauhinia megalandra fresh leaves, eight flavonoids were isolated and evaluated by rat liver microsomal glucose-6-phosphatase (G-6-Pase) bioassay, which might be a useful methodology for screening antihyperglycaemic substances. All the flavonoids assayed showed an inhibitory effect on the intact microsomal G-6-Pase: quercetin and kaempferol exhibited the lowest effect; astilbin, quercetin 3-O-alpha-rhamnoside, kaempferol 3-O-alpha-rhamnoside and quercetin 3-O-alpha-arabinoside an intermediate effect. The highest inhibitory activity was shown by quercetin 3-O-alpha-(2''-galloyl)rhamnoside and kaempferol 3-O-alpha-(2''galloyl)rhamnoside. None of the flavonoids mentioned above showed an inhibitory effect on the disrupted microsomal G-6-Pase. Quercetin 3-O-alpha-(2''-galloyl)rhamnoside and kaempferol 3-O-alpha-(2''-galloyl)rhamnoside exhibited the lowest IC50 of all the flavonoids assayed. Also, the phlorizin IC50 is reported.
Planta Medica, 2019
Common chronic conditions such as metabolic syndrome and diabetes are increasingly associated to ... more Common chronic conditions such as metabolic syndrome and diabetes are increasingly associated to metabolic and cardiovascular complications. Although Phyllanthus tenellus leaves have been used in decoctions as a popular remedy to control blood glucose levels and hypertension, its use needs a scientific basis. This study was therefore undertaken to report a phytochemical analysis of P. tenellus leaves and to test if the main active compound has potential to simultaneously tackle several pathophysiological features of metabolic syndrome and diabetes-related metabolic and vascular disorders such as hyperglycaemia, increased platelet activation, and endothelial dysfunction. We performed a partition of the methanolic extract of P. tenellus leaves among different organic solvents followed by chromatographic separation guided by the rat liver microsomal glucose-6-phosphatase assay. Two known tannins were identified by spectroscopic methods as pinocembrin-7-O-[3″-O-galloyl-4″,6″-(S)-hexahyd...
Revista de la Facultad de Medicina, 2002
European Journal of Histochemistry, 2004
During the Wilhelm Bernhard Workshop, the 18th International Workshop on the Cell Nucleus, held i... more During the Wilhelm Bernhard Workshop, the 18th International Workshop on the Cell Nucleus, held in Pavia last September, the idea was born to ask some of the participants for sending a paper for a special issue on the cell nucleus of the European Journal of Histochemistry, to celebrate the 50th anniversary of its foundation. In the following pages, the contributions of several scientists working in this field have been collected, each article having a special look and attention to a particular aspect of nuclear biology. As it was pointed out during the opening lecture of the Workshop, we had several anniversaries in 2003, which are concerned with the cell nucleus. The 50 years of the double helix paper have been celebrated all over the world, but two others are worth mentioning: the paper by Cogliati and Gautier on the synthesis of osmium ammine for the specific staining of DNA at electron microscopy was published exactly 30 years ago, and 25 years ago Dr. Wilhelm Bernhard died. Ber...
Biochemical Journal, 1973
1. The effects of the inclusion of thioacetamide in the diet on the properties of rat liver nucle... more 1. The effects of the inclusion of thioacetamide in the diet on the properties of rat liver nuclei were studied both in adolescent rats, in which the parenchymal cells contain diploid nuclei, and in young adult rats, with a high proportion of tetraploid nuclei. 2. These investigations included a survey of the sedimentation properties of the nuclei, the nuclear volumes, content of DNA, RNA and protein, the incorporation in vivo of [3H]thymidine into DNA and [14C]orotate into RNA, and measurements of the activity of RNA polymerase and ribonuclease. These studies were conducted on nuclei fractionated by zonal centrifugation. 3. In both groups of animals, exposure to thioacetamide produced large numbers of nuclei that were abnormal in their chemical composition and enzymic activity. The changes were complex as regards both the types of nuclei that were affected and in their variation with time. 4. In adolescent rats two waves of synthesis of DNA and RNA were observed, one at 3 days and ...
Biochemical Society Transactions, 1994
Biochemical Society Transactions, 1994
Biochemical Society Transactions, 1994
Archivos Venezolanos de Farmacologia y Terapeutica
The Bauhinia megalandra leaves aqueous extract, has been commonly used in Venezuela for the empir... more The Bauhinia megalandra leaves aqueous extract, has been commonly used in Venezuela for the empiric treatment of diabetes mellitus. In this work, the effect of B. megalandra aqueous extract on hepatic epinephrine or dibutyril cAMP stimulated glycogenolysis, was studied. The oral administration of the plant extract to feed rats decreased the epinephrineraised glycemia in a statystical significant way. Furthermore, liver slices from feed rats, incubated in the presence of B. megalandra extract, released less glucose in response to epinephrine or dibutiryl cAMP than controls. This results shows a decrease in the hepatic glycogenolysis due to the effect of B. megalandra leaves aqueous extract probably as result of the inhibition of the glucose-6-phosphatase enzyme.
Investigación clínica, 2008
Nuclear envelope (NE) and microsomal glucosa-6-phosphatase (G-6-Pase) activities were compared. I... more Nuclear envelope (NE) and microsomal glucosa-6-phosphatase (G-6-Pase) activities were compared. Intact microsomes were unable to hydrolyze mannose-6-phosphate (M-6-P), on the other hand, intact NE hydrolyzes this substrate. Galactose-6-phosphate showed to be a good substrate for both NE and microsomal enzymes, with similar latency to that obtained with M-6-P using microsomes. In consequence, this substrate was used to measure the NE integrity. The kinetic parameters (Kii and Kis) of the intact NE G-6-Pase for the phlorizin inhibition using glucose-6-phosphate (G-6-P) and M-6-P as substrates, were very similar. The NE T1 transporter was more sensitive to amiloride than the microsomal T1. The microsomal system was more sensitive to N-ethylmalemide (NEM) than the NE and the latter was insensitive to anion transport inhibitors DIDS and SITS, which strongly affect the microsomal enzyme. The above results allowed to postulate the presence of a hexose-6-phosphate transporter in the NE whic...
Vitae: Academia Biomédica Digital, 2010
Page 1. Julio-Septiembre N°43 ISSN 1317-987X Artículos Actividad Antihiperglicemiante de Bauhinia... more Page 1. Julio-Septiembre N°43 ISSN 1317-987X Artículos Actividad Antihiperglicemiante de Bauhinia megalandra.(Revisión) Introducción Efectos de B. megalandra sobre la neoglucogénesis y la G-6-Pasa Efectos de B. megalandra ...
Rev. Fac. Cienc. Vet, 2007
... José D. Pradere*,1, Ana Z. Ruiz E.*, Freddy González M.** y Alejandro Correa*** ... Ligamento... more ... José D. Pradere*,1, Ana Z. Ruiz E.*, Freddy González M.** y Alejandro Correa*** ... Ligamento ancho (la), riñón derecho (rd), arteria aorta (aa), uréter (u), arteria ovárica (ao), ovario derecho (od), ovario izquierdo (oi) ... Szabuniewicz, M.; Sánchez, L.; Sosa, A.; Gómez, M. 1977. ...
scielo.org.ve
How to cite Complete issue More information about this article Journal's homepage in redalyc.org ... more How to cite Complete issue More information about this article Journal's homepage in redalyc.org Scientific Information System Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Non-profit academic project, developed under the open access initiative
Rev. Fac. Med.( …, 1989
Base de dados : LILACS. Pesquisa : 86786 [Identificador único]. Referências encontradas : 1 [refi... more Base de dados : LILACS. Pesquisa : 86786 [Identificador único]. Referências encontradas : 1 [refinar]. Mostrando: 1 .. 1 no formato [Detalhado]. página 1 de 1, 1 / 1, LILACS, seleciona. para imprimir. Fotocópia. experimental, Documentos relacionados. Id: 86786. ...
Invest. clín, 1988
Base de dados : LILACS. Pesquisa : 78954 [Identificador único]. Referências encontradas : 1 [refi... more Base de dados : LILACS. Pesquisa : 78954 [Identificador único]. Referências encontradas : 1 [refinar]. Mostrando: 1 .. 1 no formato [Detalhado]. página 1 de 1, 1 / 1, LILACS, seleciona. para imprimir. Fotocópia. experimental, Documentos relacionados. Id: 78954. ...
Acta Diabetologica Latina, 1974
Page 1. DEPARTAMENTO DE CIENCIAS FISIOLOGICAS, FACULTAD DE MEDICINA UNIVERSIDAD CENTRAL DE VENEZU... more Page 1. DEPARTAMENTO DE CIENCIAS FISIOLOGICAS, FACULTAD DE MEDICINA UNIVERSIDAD CENTRAL DE VENEZUELA, CARACAS EFFECTS OF INSULIN AND GLUCOSE ON SUBCELLULAR FRACTIONS FROM RAT ADIPOSE TISSUE ...
Acta científica venezolana, 1983
Acta científica venezolana, 1978
Phytochemistry, Jan 6, 2017
Five previously undescribed triterpene saponins, billiosides A-E, and a known analogue, were isol... more Five previously undescribed triterpene saponins, billiosides A-E, and a known analogue, were isolated from the seeds of Billia rosea (Planch. & Linden) C. Ulloa & P. Jørg. Their structures were elucidated on the basis of extensive 1D and 2D NMR experiments ((1)H, (13)C, DEPT, COSY, TOCSY, NOESY, ROESY, HSQC, and HMBC) and mass spectrometry as (3β,21β,22α)-3-[(2-O-β-D-glucopyranosyl-O-[α-L-arabinopyranosyl-(1 → 4)]-β-D-glucopyranosyl)oxy]-21-[((2E,6S)-2,6-dimethyl-6-hydroxyocta-2,7-dienoyl)oxy]-22-(acetyloxy)-24-hydroxyolean-12-en-28-oic acid, (3β,21β,22α)-3-[(2-O-β-D-galactopyranosyl-β-D-glucopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O-α-L-arabinopyranosyl-(1 → 4)-β-D-glucopyranoside, (3β,21β,22α)-3-[(2-O-β-D-galactopyranosyl-O-[α-L-arabinopyranosyl-(1 → 4)]-β-D-xylopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O-β-D-glucopyranoside, (3β,21β,22α)-3-[(2-O-β-D-galactopyranosyl-O-[α-L-arabinopyranosyl-(1 → 4)]-β-D-glucopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O-β-D-gluco...
Phytotherapy Research, 2005
From the methanol extract of Bauhinia megalandra fresh leaves, eight flavonoids were isolated and... more From the methanol extract of Bauhinia megalandra fresh leaves, eight flavonoids were isolated and evaluated by rat liver microsomal glucose-6-phosphatase (G-6-Pase) bioassay, which might be a useful methodology for screening antihyperglycaemic substances. All the flavonoids assayed showed an inhibitory effect on the intact microsomal G-6-Pase: quercetin and kaempferol exhibited the lowest effect; astilbin, quercetin 3-O-alpha-rhamnoside, kaempferol 3-O-alpha-rhamnoside and quercetin 3-O-alpha-arabinoside an intermediate effect. The highest inhibitory activity was shown by quercetin 3-O-alpha-(2''-galloyl)rhamnoside and kaempferol 3-O-alpha-(2''galloyl)rhamnoside. None of the flavonoids mentioned above showed an inhibitory effect on the disrupted microsomal G-6-Pase. Quercetin 3-O-alpha-(2''-galloyl)rhamnoside and kaempferol 3-O-alpha-(2''-galloyl)rhamnoside exhibited the lowest IC50 of all the flavonoids assayed. Also, the phlorizin IC50 is reported.
Planta Medica, 2019
Common chronic conditions such as metabolic syndrome and diabetes are increasingly associated to ... more Common chronic conditions such as metabolic syndrome and diabetes are increasingly associated to metabolic and cardiovascular complications. Although Phyllanthus tenellus leaves have been used in decoctions as a popular remedy to control blood glucose levels and hypertension, its use needs a scientific basis. This study was therefore undertaken to report a phytochemical analysis of P. tenellus leaves and to test if the main active compound has potential to simultaneously tackle several pathophysiological features of metabolic syndrome and diabetes-related metabolic and vascular disorders such as hyperglycaemia, increased platelet activation, and endothelial dysfunction. We performed a partition of the methanolic extract of P. tenellus leaves among different organic solvents followed by chromatographic separation guided by the rat liver microsomal glucose-6-phosphatase assay. Two known tannins were identified by spectroscopic methods as pinocembrin-7-O-[3″-O-galloyl-4″,6″-(S)-hexahyd...