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Papers by John Kenneth Ramos
Archivos de oftalmología de Buenos Aires
Acta medica Philippina
The non-structural 5B (NS5B) gene is the target region to identify hepatitis C virus (HCV) subtyp... more The non-structural 5B (NS5B) gene is the target region to identify hepatitis C virus (HCV) subtypes. However, it is not always possible to amplify this region because of inherently high sequence variability. Nucleotide sequences of the non-structural 5A (NS5A) and NS5B genes and its concordance were determined from patients infected with HCV genotype 1 (HCV-1). Among the 30 HCV-1 samples, 7 (23%) were identified as subtype 1a and 23 (77%) were identified as 1b by NS5A sequencing. Sequence analysis of the NS5B showed that 13 (43%) were identified as 1a and 17 (57%) were identified as 1b. Out of the 13 samples identified as 1a by NS5B, 6 (46%) were correctly identified by NS5A. Of the 17 samples identified as 1b by NS5B, 16 (94%) were correctly identified by NS5A. The presence of glutamic acid (E) or aspartic acid (D) at position 2225 in the NS5A differentiates 1a from 1b subtypes, respectively. This study showed that the NS5A sequencing can identify HCV-1a and 1b subtypes with predic...
Journal of Insect Physiology, 2015
Pharmacology Biochemistry and Behavior, 1992
PHARMACOL BIOCHEM BEHAV 41(3) 469-474, 1992.-Perinatal exposure to cannahinoid derivatives has be... more PHARMACOL BIOCHEM BEHAV 41(3) 469-474, 1992.-Perinatal exposure to cannahinoid derivatives has been shown to affect brain development. In this work, we studied the changes induced by maternal exposure to cannahinoids during gestation and lactation on the dopaminergic activity in the prosencephalic area of offspring of several days of development. This brain area contains an increasing population of dopaminergic terminals from the different dopaminergic pathways that become differentiated in the adult rat. We measured the endogenous content of dopamine and its intraneuronal metabolite, L-3,4-dihydroxyphenylacetic acid, and the activity of tyrosine hydroxylase as indices of dopaminergic activity. Results showed that perinatal exposure to cannabinoids caused several changes in the evolution of the dopaminergic indices studied. These changes were mainly observed in males. The only alteration in females occurred on the tenth day of development: An increase in dopamine content was observed with no changes in either the content of L-3,4-dihydroxyphenylacetic acid or tyrosine hydroxylase activity. In males, the content of both dopamine and L-3,4-dihydroxyphenylacetic acid were decreased on the day previous to birth in the animals exposed to cannabinoids, Although the reduction in its metabolite disappeared on the fifth day, the decrease in dopamine was maintained and it was correlated with a decrease in tyrosine hydroxylase activity. However, this decrease in the activity of tyrosine hydroxylase was followed by an increase on the tenth day. These results allow us to conclude that perinatal exposure to cannabinoids produces changes in the normal development of several indices of the activity of dopaminergic neurons in the brain area containing the most important population of dopaminergic endings. These changes were mainly observed in males. They could be responsible for a long-term alteration in the neurological processes in which these neurons are involved in the adult.
Developmental Brain Research, 1990
Perinatal exposure to cannabinoid derivatives has been shown to produce effects on brain developm... more Perinatal exposure to cannabinoid derivatives has been shown to produce effects on brain development. In this study, we evaluated the changes induced by maternal exposure to hashish crude extract (HCE) during gestation and lactation in several biochemical indices of dopamine activity in the striatum and the limbic forebrain of offspring. Studies were performed either during the HCE exposure or after drug withdrawal. Perinatal exposure to HCE reduced the number of striatal D t binding sites in females and increased the L-3,4-dihydroxyphenylacetic acid/dopamine (DOPAC/DA) ratio, whereas an increase in the number of striatal D 2 binding sites, with a reduction in their affinity, and a decrease in the activity of tyrosine hydroxylase (TH) were observed in males. The DOPAC/DA ratio was also increased in the limbic forebrain in HCE-exposed females, but there were no changes in binding site parameters. Most of these effects disappeared after cessation of cannabinoid treatment, but the decrease in striatal TH activity in males was maintained during drug withdrawal. Interestingly, the affinity of D 2 receptors in the striatum of females, the number of striatal D 1 receptors in males, and the limbic TH activity in males increased after the cessation of drug treatment. These results allow us to conclude that: (1) the effects of perinatal exposure to HCE were different depending on the sex and the specific brain area studied; and (2) most of the effects disappeared after cessation of cannabinoid treatment, although some new changes then appeared.
Brain Research, 1989
Recent evidence has shown that sexual steroids are able to modify the activity of the dopaminergi... more Recent evidence has shown that sexual steroids are able to modify the activity of the dopaminergic nigrostriatal pathway. Most of this evidence has been obtained from the individual effects of these hormones, but there is less information about possible interrelationships between both. In order to further explore this question, ovariectomized adult rats were submitted to estradiol (E2) or vehicle injections during 3 days and, at the third day, were also submitted to a single injection of progesterone (P) or vehicle at 4, 10, 24 and 32 h before decapitation. Additionally, the effect of injections of 2-hydroxyestradiol (2OH-E2), which has been involved as local mediator in the effects of E2, was also examined. The two striata of each animal were removed and used for determination of number and affinity of dopamine D2-receptors, using [3H]spiroperidol as ligand. Administration of E2 produced a significant reduction in the number of striatal dopaminergic receptors 10 h after the last steroid injection, which was followed by an increase at 24 h. Administration of P briefly decreased the number of dopaminergic receptors at 4 h after the steroid injection. This effect was not observed in animals pretreated with E2, in which administration of P produced an apparent increase 24 h after the steroid treatment. On the other hand, the 2-hydroxylated derivative of E2 does not seem to mediate in the stimulatory action of this estrogen, since it was unable to increase the number of dopaminergic receptors by itself or priming the action of P. The affinity of dopaminergic receptors for [3H]spiroperidol was not significantly altered after all the steroid treatments.(ABSTRACT TRUNCATED AT 250 WORDS)
Digest of Technical Papers. 2005 Symposium on VLSI Circuits, 2005., 2005
Journal of bacteriology, 1984
Like all other organisms, Saccharomyces cerevisiae accu-mulates K+ from the external medium to fu... more Like all other organisms, Saccharomyces cerevisiae accu-mulates K+ from the external medium to fulfill cellular requirements. The transport of K+ in yeasts has been the subject of very extensive studies (2) that have clarified many kinetic aspects of the process. All of the alkali cations ...
Archivos de oftalmología de Buenos Aires
Acta medica Philippina
The non-structural 5B (NS5B) gene is the target region to identify hepatitis C virus (HCV) subtyp... more The non-structural 5B (NS5B) gene is the target region to identify hepatitis C virus (HCV) subtypes. However, it is not always possible to amplify this region because of inherently high sequence variability. Nucleotide sequences of the non-structural 5A (NS5A) and NS5B genes and its concordance were determined from patients infected with HCV genotype 1 (HCV-1). Among the 30 HCV-1 samples, 7 (23%) were identified as subtype 1a and 23 (77%) were identified as 1b by NS5A sequencing. Sequence analysis of the NS5B showed that 13 (43%) were identified as 1a and 17 (57%) were identified as 1b. Out of the 13 samples identified as 1a by NS5B, 6 (46%) were correctly identified by NS5A. Of the 17 samples identified as 1b by NS5B, 16 (94%) were correctly identified by NS5A. The presence of glutamic acid (E) or aspartic acid (D) at position 2225 in the NS5A differentiates 1a from 1b subtypes, respectively. This study showed that the NS5A sequencing can identify HCV-1a and 1b subtypes with predic...
Journal of Insect Physiology, 2015
Pharmacology Biochemistry and Behavior, 1992
PHARMACOL BIOCHEM BEHAV 41(3) 469-474, 1992.-Perinatal exposure to cannahinoid derivatives has be... more PHARMACOL BIOCHEM BEHAV 41(3) 469-474, 1992.-Perinatal exposure to cannahinoid derivatives has been shown to affect brain development. In this work, we studied the changes induced by maternal exposure to cannahinoids during gestation and lactation on the dopaminergic activity in the prosencephalic area of offspring of several days of development. This brain area contains an increasing population of dopaminergic terminals from the different dopaminergic pathways that become differentiated in the adult rat. We measured the endogenous content of dopamine and its intraneuronal metabolite, L-3,4-dihydroxyphenylacetic acid, and the activity of tyrosine hydroxylase as indices of dopaminergic activity. Results showed that perinatal exposure to cannabinoids caused several changes in the evolution of the dopaminergic indices studied. These changes were mainly observed in males. The only alteration in females occurred on the tenth day of development: An increase in dopamine content was observed with no changes in either the content of L-3,4-dihydroxyphenylacetic acid or tyrosine hydroxylase activity. In males, the content of both dopamine and L-3,4-dihydroxyphenylacetic acid were decreased on the day previous to birth in the animals exposed to cannabinoids, Although the reduction in its metabolite disappeared on the fifth day, the decrease in dopamine was maintained and it was correlated with a decrease in tyrosine hydroxylase activity. However, this decrease in the activity of tyrosine hydroxylase was followed by an increase on the tenth day. These results allow us to conclude that perinatal exposure to cannabinoids produces changes in the normal development of several indices of the activity of dopaminergic neurons in the brain area containing the most important population of dopaminergic endings. These changes were mainly observed in males. They could be responsible for a long-term alteration in the neurological processes in which these neurons are involved in the adult.
Developmental Brain Research, 1990
Perinatal exposure to cannabinoid derivatives has been shown to produce effects on brain developm... more Perinatal exposure to cannabinoid derivatives has been shown to produce effects on brain development. In this study, we evaluated the changes induced by maternal exposure to hashish crude extract (HCE) during gestation and lactation in several biochemical indices of dopamine activity in the striatum and the limbic forebrain of offspring. Studies were performed either during the HCE exposure or after drug withdrawal. Perinatal exposure to HCE reduced the number of striatal D t binding sites in females and increased the L-3,4-dihydroxyphenylacetic acid/dopamine (DOPAC/DA) ratio, whereas an increase in the number of striatal D 2 binding sites, with a reduction in their affinity, and a decrease in the activity of tyrosine hydroxylase (TH) were observed in males. The DOPAC/DA ratio was also increased in the limbic forebrain in HCE-exposed females, but there were no changes in binding site parameters. Most of these effects disappeared after cessation of cannabinoid treatment, but the decrease in striatal TH activity in males was maintained during drug withdrawal. Interestingly, the affinity of D 2 receptors in the striatum of females, the number of striatal D 1 receptors in males, and the limbic TH activity in males increased after the cessation of drug treatment. These results allow us to conclude that: (1) the effects of perinatal exposure to HCE were different depending on the sex and the specific brain area studied; and (2) most of the effects disappeared after cessation of cannabinoid treatment, although some new changes then appeared.
Brain Research, 1989
Recent evidence has shown that sexual steroids are able to modify the activity of the dopaminergi... more Recent evidence has shown that sexual steroids are able to modify the activity of the dopaminergic nigrostriatal pathway. Most of this evidence has been obtained from the individual effects of these hormones, but there is less information about possible interrelationships between both. In order to further explore this question, ovariectomized adult rats were submitted to estradiol (E2) or vehicle injections during 3 days and, at the third day, were also submitted to a single injection of progesterone (P) or vehicle at 4, 10, 24 and 32 h before decapitation. Additionally, the effect of injections of 2-hydroxyestradiol (2OH-E2), which has been involved as local mediator in the effects of E2, was also examined. The two striata of each animal were removed and used for determination of number and affinity of dopamine D2-receptors, using [3H]spiroperidol as ligand. Administration of E2 produced a significant reduction in the number of striatal dopaminergic receptors 10 h after the last steroid injection, which was followed by an increase at 24 h. Administration of P briefly decreased the number of dopaminergic receptors at 4 h after the steroid injection. This effect was not observed in animals pretreated with E2, in which administration of P produced an apparent increase 24 h after the steroid treatment. On the other hand, the 2-hydroxylated derivative of E2 does not seem to mediate in the stimulatory action of this estrogen, since it was unable to increase the number of dopaminergic receptors by itself or priming the action of P. The affinity of dopaminergic receptors for [3H]spiroperidol was not significantly altered after all the steroid treatments.(ABSTRACT TRUNCATED AT 250 WORDS)
Digest of Technical Papers. 2005 Symposium on VLSI Circuits, 2005., 2005
Journal of bacteriology, 1984
Like all other organisms, Saccharomyces cerevisiae accu-mulates K+ from the external medium to fu... more Like all other organisms, Saccharomyces cerevisiae accu-mulates K+ from the external medium to fulfill cellular requirements. The transport of K+ in yeasts has been the subject of very extensive studies (2) that have clarified many kinetic aspects of the process. All of the alkali cations ...