Henry Pacheco - Academia.edu (original) (raw)
Papers by Henry Pacheco
Journal of Neurochemistry, 1982
Abstract: When synaptosomes from rat brain were incubated with S-adenosylmethionine (10−3M), nora... more Abstract: When synaptosomes from rat brain were incubated with S-adenosylmethionine (10−3M), noradrenaline uptake and KCI-stimulated release were decreased. These effects were dependent on MgCl2, temperature, and incubation time. We have investigated the enzymatic methylation of phosphatidylethanolamine to give phosphatidylcholine.
Biochemical Pharmacology, 1981
Clinica Chimica Acta, 1987
Experientia, 1978
Added to a striatal synaptosomal homogenate of rat brain, CDP-choline 10−4 M inhibits the uptake ... more Added to a striatal synaptosomal homogenate of rat brain, CDP-choline 10−4 M inhibits the uptake of norepinephrine (NE), dopamine (DA) and serotonin (5 HT) in a competitive fashion and enhances the uptake of tyrosine and tryptophan; administered to animals, CDP-choline (50 mg/kg/l h/i.v.) inhibits only the in vitro uptake of DA but enhances the uptake of precursors.
The Regional Concentrations of S-Adenosyl-l-Methionine, S-Adenosyl-l-Homocysteine, and Adenosine in Rat Brain
Journal of Neurochemistry, 1982
Abstract: The concentrations of S-adenosyl-l-methionine (SAM), S-adenosyl-l-homocysteine (SAH), a... more Abstract: The concentrations of S-adenosyl-l-methionine (SAM), S-adenosyl-l-homocysteine (SAH), and adenosine (Ado) were determined in whole brain and rat brain regions by HPLC. The whole brain contains, respectively, 22 nmol, 1 nmol, and 64 nmol of SAM, SAH, and Ado per g of wet tissue. Their distribution indicated that SAM and SAH levels are highest in brainstem, whereas the Ado level is highest in cortex. With aging the SAM concentrations decrease in whole brain, brainstem, and hypothalamus (–25%) and SAH levels increase by 90% in striatum and by 160% in cerebellum, while Ado levels are increased in all regions by 100–180%.
SAH analogs, modified in the aminoacid region, inhibitors of phosphatidyl-ethanolamine methylase activity and 3H-SAH binding to rat brain membranes
Life Sciences, 1982
The study of phosphatidylethanolamine methylase inhibition by 10 SAH analogs points out the impor... more The study of phosphatidylethanolamine methylase inhibition by 10 SAH analogs points out the importance of the L-homocysteine amino and carboxylic groups and the sulfur atom for the activity of SAH. Besides, the inhibition of phosphatidylethanolamine methylase by SAH analogs is correlated with their affinity for the 3H-SAH binding sites on the rat cortical membranes.
Autoradiographic localization of [14C]8-S-adenosyl-l-homocysteine in rat brain
Neuroscience Letters, 1984
Following intracarotid injection of [14C]8-S-adenosyl-L-homocysteine ( [14C]SAH) in the rat, radi... more Following intracarotid injection of [14C]8-S-adenosyl-L-homocysteine ( [14C]SAH) in the rat, radioactivity was localized by autoradiographic detection in the circumventricular organs, such as the pineal gland, choroid plexuses and area postrema, which lie outside the blood-brain barrier. HPLC analysis indicated a decrease of [14C]SAH radioactivity in these structures from 1 to 45 min, after injection. These results are discussed and related to the known pharmacological properties of SAH.
Purification of cAMP-specific phosphodiesterase from rat heart by affinity chromatography on immobilized rolipram
Biochemical and Biophysical Research Communications, 1986
Biochemical Pharmacology, 1984
Phospholipid Methylase Activity, [ 3 H]S-Adenosyl-l-Homocysteine Binding, and S-Adenosyl-l-Methionine and S-Adenosyl-l-Homocysteine Levels in Rat Brain During Maturation
Journal of Neurochemistry, 1985
Abstract: The changes in activity of phospholipid methyltransferase I and [3H]S-adenosyl-l-homocy... more Abstract: The changes in activity of phospholipid methyltransferase I and [3H]S-adenosyl-l-homocysteine ([3H]SAH) binding were determined in cortical membrane preparations from newborn rats and rats 1, 2, and 8 months old. The activity of phospholipid methyltransferase I and the [3H]SAH binding were significantly greater (respectively, +30 and +40%) in newborn rats than in 1-, 2-, and 8-month-old rats. The methylated products at days 1 and 30 were identical. These changes in methyltransferase activity may be correlated with variations in concentration of S-adenosyl-l-methionine (SAM) and SAH. The endogenous SAM level was higher and the SAH level was lower in newborn compared with adult rats. These data suggested that the processes of methylation were favored in newborn rats. The modifications observed after treatment with l-homocysteine reinforced this hypothesis.
Biochemical Pharmacology, 1988
The resolution as well
Experientia, 1979
S-Adenosylhomocysteine (10−7−10−5 M) activated norepinephrine (NE) and serotonin (5HT) in vitro u... more S-Adenosylhomocysteine (10−7−10−5 M) activated norepinephrine (NE) and serotonin (5HT) in vitro uptake in synaptosomal preparations from rat brain, but did not affect dopamine (DA) uptake. When administered to rats (7 mg/kg i.p.), it had the same effect on in vitro NE and 5HT uptake. It did not affect NE and 5HT release.
Journal of Neurochemistry, 1981
Membranes from rat cerebral cortex are able to bind S-adenosyl-L-homocysteine (SAH) with a KD of ... more Membranes from rat cerebral cortex are able to bind S-adenosyl-L-homocysteine (SAH) with a KD of 5. 10-7 M and n of 170 pmol/g fresh tissue (i.e. 20 mg protein). The binding is enhanced by Mg2+ and Ca2- but not K+ and Na+, γ-Aminobutyric acid, diazepine, noradrenaline and a antagonists are without any effect; S-adenosyl-L-methionine, adenosine and adenosine triphosphate inhibit SAH binding. Linkage with an adenosine receptor has not been expressly demonstrated by our method. SAH binding proteins are more abundant in the crude synaptosomal pellet (P2). A similar fixation seems to occur on brain membranes after [3H]SAH administration to rat. The binding might be linked to a methylase activity or an adenosine receptor.
Analysis of cyclic nucleotide phosphodiesterase by isoelectric focusing coupled to a specific activity stain
Analytical Biochemistry, 1983
The procedure described allowed a convenient analysis of cyclic nucleotide phosphodiesterase. The... more The procedure described allowed a convenient analysis of cyclic nucleotide phosphodiesterase. The different phosphodiesterase forms present in a crude cytosolic preparation from rat heart were separated by isoelectric focusing on a polyacrylamide gel plate. Phosphodiesterase activity bands were rendered evident by a specific staining method. They were then characterized by means of their substrate specificity and their sensitivity to selective phosphodiesterase inhibitors. The correspondence between the stain bands and the previously described activity peaks, obtained by a preparative technique and detected by radioisotopic enzyme assay, was also investigated.
Increase of in vitro brain [3H]muscimol binding after l-homocysteine administration to rat
Neuroscience Letters, 1987
Phosphatidylethanolamine methylation in membranes from rat cerebral cortex: Effect of exogenous phospholipids and S-adenosylhomocysteine
Biochemical and Biophysical Research Communications, 1981
Phosphatidyl ethanolamine methylation was compared in alveolar macrophage membrane from asthmatic... more Phosphatidyl ethanolamine methylation was compared in alveolar macrophage membrane from asthmatic and control subjects. Phosphatidyl ethanolamine methylase activity was determined by measuring the incorporation of (3H) methyl group from (3H) adenosyl methionine into membrane phospholipids. (3H) methyl group incorporation was significantly higher in macrophages from asthmatic patients. This result is consistent with macrophage membrane activation and could signify: a membrane phospholipid pool regeneration after allergenic or toxic disturbance or an enzymatic activation by inflammatory mediators.
Cyclic nucleotide phosphodiesterase from a particulate fraction of rat heart. Solubilization and characterization of a single enzymatic form
Biochemical and Biophysical Research Communications, 1981
... EVIDENCE FOR AN ACTIVATOR DEFICIENT FORM. Toni Lindl and Grace Chapman Fachbereich Biologie, ... more ... EVIDENCE FOR AN ACTIVATOR DEFICIENT FORM. Toni Lindl and Grace Chapman Fachbereich Biologie, University of Konstanz, POB 7733, D7750 Konstanz, W. Germany Received July 1,1976 Summary. ... Lowry, OH, Rosebrough, NJ, Farr, AL, and Randall, RJJ Biol. Chem. ...
Activity of cyclic AMP phosphodiesterase and methyltransferases in leukocyte membranes from allergic patients
Clinica Chimica Acta, 1984
Cyclic AMP metabolism and methylation of phospholipids are central events which occur at the memb... more Cyclic AMP metabolism and methylation of phospholipids are central events which occur at the membrane level. Since a dysfunction of cell membranes seems to characterize some allergic diseases, we investigated cyclic AMP phosphodiesterase and methyltransferase activities in leukocyte membrane fractions obtained from healthy volunteers and from allergic patients. The allergic group presented a significantly decreased methyltransferase activity compared with a control group, whereas cyclic AMP phosphodiesterase and noradrenaline (NA)-stimulated methyltransferase were found to be increased with respect to the control group. A significant correlation has been found between cyclic AMP phosphodiesterase and NA-stimulated methyltransferase with both control and allergic subjects, which suggests close relationships between these two enzymes within the cell membrane.
Journal of Neurochemistry, 1982
Abstract: When synaptosomes from rat brain were incubated with S-adenosylmethionine (10−3M), nora... more Abstract: When synaptosomes from rat brain were incubated with S-adenosylmethionine (10−3M), noradrenaline uptake and KCI-stimulated release were decreased. These effects were dependent on MgCl2, temperature, and incubation time. We have investigated the enzymatic methylation of phosphatidylethanolamine to give phosphatidylcholine.
Biochemical Pharmacology, 1981
Clinica Chimica Acta, 1987
Experientia, 1978
Added to a striatal synaptosomal homogenate of rat brain, CDP-choline 10−4 M inhibits the uptake ... more Added to a striatal synaptosomal homogenate of rat brain, CDP-choline 10−4 M inhibits the uptake of norepinephrine (NE), dopamine (DA) and serotonin (5 HT) in a competitive fashion and enhances the uptake of tyrosine and tryptophan; administered to animals, CDP-choline (50 mg/kg/l h/i.v.) inhibits only the in vitro uptake of DA but enhances the uptake of precursors.
The Regional Concentrations of S-Adenosyl-l-Methionine, S-Adenosyl-l-Homocysteine, and Adenosine in Rat Brain
Journal of Neurochemistry, 1982
Abstract: The concentrations of S-adenosyl-l-methionine (SAM), S-adenosyl-l-homocysteine (SAH), a... more Abstract: The concentrations of S-adenosyl-l-methionine (SAM), S-adenosyl-l-homocysteine (SAH), and adenosine (Ado) were determined in whole brain and rat brain regions by HPLC. The whole brain contains, respectively, 22 nmol, 1 nmol, and 64 nmol of SAM, SAH, and Ado per g of wet tissue. Their distribution indicated that SAM and SAH levels are highest in brainstem, whereas the Ado level is highest in cortex. With aging the SAM concentrations decrease in whole brain, brainstem, and hypothalamus (–25%) and SAH levels increase by 90% in striatum and by 160% in cerebellum, while Ado levels are increased in all regions by 100–180%.
SAH analogs, modified in the aminoacid region, inhibitors of phosphatidyl-ethanolamine methylase activity and 3H-SAH binding to rat brain membranes
Life Sciences, 1982
The study of phosphatidylethanolamine methylase inhibition by 10 SAH analogs points out the impor... more The study of phosphatidylethanolamine methylase inhibition by 10 SAH analogs points out the importance of the L-homocysteine amino and carboxylic groups and the sulfur atom for the activity of SAH. Besides, the inhibition of phosphatidylethanolamine methylase by SAH analogs is correlated with their affinity for the 3H-SAH binding sites on the rat cortical membranes.
Autoradiographic localization of [14C]8-S-adenosyl-l-homocysteine in rat brain
Neuroscience Letters, 1984
Following intracarotid injection of [14C]8-S-adenosyl-L-homocysteine ( [14C]SAH) in the rat, radi... more Following intracarotid injection of [14C]8-S-adenosyl-L-homocysteine ( [14C]SAH) in the rat, radioactivity was localized by autoradiographic detection in the circumventricular organs, such as the pineal gland, choroid plexuses and area postrema, which lie outside the blood-brain barrier. HPLC analysis indicated a decrease of [14C]SAH radioactivity in these structures from 1 to 45 min, after injection. These results are discussed and related to the known pharmacological properties of SAH.
Purification of cAMP-specific phosphodiesterase from rat heart by affinity chromatography on immobilized rolipram
Biochemical and Biophysical Research Communications, 1986
Biochemical Pharmacology, 1984
Phospholipid Methylase Activity, [ 3 H]S-Adenosyl-l-Homocysteine Binding, and S-Adenosyl-l-Methionine and S-Adenosyl-l-Homocysteine Levels in Rat Brain During Maturation
Journal of Neurochemistry, 1985
Abstract: The changes in activity of phospholipid methyltransferase I and [3H]S-adenosyl-l-homocy... more Abstract: The changes in activity of phospholipid methyltransferase I and [3H]S-adenosyl-l-homocysteine ([3H]SAH) binding were determined in cortical membrane preparations from newborn rats and rats 1, 2, and 8 months old. The activity of phospholipid methyltransferase I and the [3H]SAH binding were significantly greater (respectively, +30 and +40%) in newborn rats than in 1-, 2-, and 8-month-old rats. The methylated products at days 1 and 30 were identical. These changes in methyltransferase activity may be correlated with variations in concentration of S-adenosyl-l-methionine (SAM) and SAH. The endogenous SAM level was higher and the SAH level was lower in newborn compared with adult rats. These data suggested that the processes of methylation were favored in newborn rats. The modifications observed after treatment with l-homocysteine reinforced this hypothesis.
Biochemical Pharmacology, 1988
The resolution as well
Experientia, 1979
S-Adenosylhomocysteine (10−7−10−5 M) activated norepinephrine (NE) and serotonin (5HT) in vitro u... more S-Adenosylhomocysteine (10−7−10−5 M) activated norepinephrine (NE) and serotonin (5HT) in vitro uptake in synaptosomal preparations from rat brain, but did not affect dopamine (DA) uptake. When administered to rats (7 mg/kg i.p.), it had the same effect on in vitro NE and 5HT uptake. It did not affect NE and 5HT release.
Journal of Neurochemistry, 1981
Membranes from rat cerebral cortex are able to bind S-adenosyl-L-homocysteine (SAH) with a KD of ... more Membranes from rat cerebral cortex are able to bind S-adenosyl-L-homocysteine (SAH) with a KD of 5. 10-7 M and n of 170 pmol/g fresh tissue (i.e. 20 mg protein). The binding is enhanced by Mg2+ and Ca2- but not K+ and Na+, γ-Aminobutyric acid, diazepine, noradrenaline and a antagonists are without any effect; S-adenosyl-L-methionine, adenosine and adenosine triphosphate inhibit SAH binding. Linkage with an adenosine receptor has not been expressly demonstrated by our method. SAH binding proteins are more abundant in the crude synaptosomal pellet (P2). A similar fixation seems to occur on brain membranes after [3H]SAH administration to rat. The binding might be linked to a methylase activity or an adenosine receptor.
Analysis of cyclic nucleotide phosphodiesterase by isoelectric focusing coupled to a specific activity stain
Analytical Biochemistry, 1983
The procedure described allowed a convenient analysis of cyclic nucleotide phosphodiesterase. The... more The procedure described allowed a convenient analysis of cyclic nucleotide phosphodiesterase. The different phosphodiesterase forms present in a crude cytosolic preparation from rat heart were separated by isoelectric focusing on a polyacrylamide gel plate. Phosphodiesterase activity bands were rendered evident by a specific staining method. They were then characterized by means of their substrate specificity and their sensitivity to selective phosphodiesterase inhibitors. The correspondence between the stain bands and the previously described activity peaks, obtained by a preparative technique and detected by radioisotopic enzyme assay, was also investigated.
Increase of in vitro brain [3H]muscimol binding after l-homocysteine administration to rat
Neuroscience Letters, 1987
Phosphatidylethanolamine methylation in membranes from rat cerebral cortex: Effect of exogenous phospholipids and S-adenosylhomocysteine
Biochemical and Biophysical Research Communications, 1981
Phosphatidyl ethanolamine methylation was compared in alveolar macrophage membrane from asthmatic... more Phosphatidyl ethanolamine methylation was compared in alveolar macrophage membrane from asthmatic and control subjects. Phosphatidyl ethanolamine methylase activity was determined by measuring the incorporation of (3H) methyl group from (3H) adenosyl methionine into membrane phospholipids. (3H) methyl group incorporation was significantly higher in macrophages from asthmatic patients. This result is consistent with macrophage membrane activation and could signify: a membrane phospholipid pool regeneration after allergenic or toxic disturbance or an enzymatic activation by inflammatory mediators.
Cyclic nucleotide phosphodiesterase from a particulate fraction of rat heart. Solubilization and characterization of a single enzymatic form
Biochemical and Biophysical Research Communications, 1981
... EVIDENCE FOR AN ACTIVATOR DEFICIENT FORM. Toni Lindl and Grace Chapman Fachbereich Biologie, ... more ... EVIDENCE FOR AN ACTIVATOR DEFICIENT FORM. Toni Lindl and Grace Chapman Fachbereich Biologie, University of Konstanz, POB 7733, D7750 Konstanz, W. Germany Received July 1,1976 Summary. ... Lowry, OH, Rosebrough, NJ, Farr, AL, and Randall, RJJ Biol. Chem. ...
Activity of cyclic AMP phosphodiesterase and methyltransferases in leukocyte membranes from allergic patients
Clinica Chimica Acta, 1984
Cyclic AMP metabolism and methylation of phospholipids are central events which occur at the memb... more Cyclic AMP metabolism and methylation of phospholipids are central events which occur at the membrane level. Since a dysfunction of cell membranes seems to characterize some allergic diseases, we investigated cyclic AMP phosphodiesterase and methyltransferase activities in leukocyte membrane fractions obtained from healthy volunteers and from allergic patients. The allergic group presented a significantly decreased methyltransferase activity compared with a control group, whereas cyclic AMP phosphodiesterase and noradrenaline (NA)-stimulated methyltransferase were found to be increased with respect to the control group. A significant correlation has been found between cyclic AMP phosphodiesterase and NA-stimulated methyltransferase with both control and allergic subjects, which suggests close relationships between these two enzymes within the cell membrane.