Claudia Hallal | Universidad Autónoma del Estado de Morelos (original) (raw)
Papers by Claudia Hallal
In monocytes and macrophages, activation of the tyrosine kinase Syk is an essential step in the b... more In monocytes and macrophages, activation of the tyrosine kinase Syk is an essential step in the biochemical cascade linking aggregation of receptors for immunoglobulin G (FcgammaR) to initiation of effector functions. An increase in Syk activation during differentiation of myeloid cells by different agents has been reported. We studied the activation state of Syk in response to FcgammaRII crosslinking in monocytic cells before and after in vitro differentiation with 1alpha, 25-dihydroxy-vitamin D3. We show here that while in undifferentiated THP-1 cells clustering of FcgammaRII induces significant phosphorylation and activation of Syk, in THP-1 cells differentiated in vitro by 1alpha, 25-dihydroxy-vitamin D3, FcgammaRII crosslinking induced a decrease in Syk activity. In vitro differentiation did not induce changes in the expression of FcgammaRII isoforms. The observed effect on Syk activation though FcgammaRII could be mediated by differentiation-induced changes in the expression a...
Immunology letters, 2005
Fcγ receptor (FcγR)-mediated phagocytosis by mononuclear phagocytes is an essential function in h... more Fcγ receptor (FcγR)-mediated phagocytosis by mononuclear phagocytes is an essential function in host defense. This process is initiated by crosslinking of membrane FcγRs, which induces phosphorylation and activation of Src and Syk tyrosine kinases. Activation of these ...
International Journal of Morphology, 2013
The purpose of this study was to analyze the macroscopic morphometry of the ovaries, uterus and v... more The purpose of this study was to analyze the macroscopic morphometry of the ovaries, uterus and vagina in rabbit does in the first, second and third parturition at 24 hours post-weaning in order to determine if there are differences between parturitions. Weaning of the litter was performed at 30 days post-partum and 24 hours later the does were euthanized. Right and left ovaries, uterine horns-cervix and vagina were removed, and the length of each one was measured. Significant differences were found in the average of the right ovary length between the first group with respect to second and third parturition group (P ≤ 0.05 and P ≤ 0.01). Also, left ovary length was different between the first and second with respect to third parturition group (P <0.001). Average total ovary length increased significantly as the number of parturitions increased in second and third parturition groups (P ≤ 0.01 and P≤0.001). The weight of the left and right ovaries was higher in does in their second and third parturition when compared to those in their first (P≤ 0.5; P≤ 0.01). The average total ovary weight increased significantly as the number of parturitions in second and third parturition groups (P≤0.001). The length of the left and right uterine horn-cervix of the rabbits after second and third parturition decreased when compared to that of females in their first parturition (P≤ 0.05; P≤0.001). The average total uterine horns-cervix length decreased significantly as the number of parturitions in second and third parturition groups (P≤0.001). Furthermore, vagina length in females in their third parturition was greater than that of first and second parturition (P≤ 0.01).The color of the vulva of the majority of females in their first parturition (3/4) was pale pink while. In contrast, the majority of females in their second parturition (3/4) had their vulva intensely red. All of the females (4/4) in the third parturition group had their vulva intensely red. We conclude that in female rabbits the macroscopic morphometric characteristics of ovaries, uterus and vagina, at 24 hours post-weaning vary according to the number of parturitions.
BioMed Research International, 2013
Bacillus thuringiensisis a gram-positive soil-dwelling bacterium that is commonly used as a biolo... more Bacillus thuringiensisis a gram-positive soil-dwelling bacterium that is commonly used as a biological pesticide. This bacterium may also be used for biological control of helminth parasites in domestic animals. In this study, we evaluated the possible ovicidal and cestocidal effects of a total protein extract ofB. thuringiensisnative strains on the zoonotic cestode parasite of dogs,Dipylidium caninum(D. caninum). Dose and time response curves were determined by coincubatingB. thuringiensisproteins at concentration ranging from 100 to 1000 μg/mL along with 4000 egg capsules ofD. caninum. Egg viability was evaluated using the trypan blue exclusion test. The lethal concentration of toxins on eggs was 600 μg/ml, and the best incubation time to produce this effect was 3 h. In the adult stage, the motility and the thickness of the tegument were used as indicators of damage. The motility was inhibited by 100% after 8 hours of culture compared to the control group, while the thickness of t...
Parasites & Vectors, 2013
Background: Parasitic diseases are important in animal production because they cause high economi... more Background: Parasitic diseases are important in animal production because they cause high economic losses. Affected animals often exhibit stereotypical behavioral alterations such as anorexia and inactivity, among others. Among the diseases that commonly affect domestic rabbits is mange, which is caused by the mite Psoroptes cuniculi. Therefore, within the context of the host-parasite relationship, it is critical to understand the mechanisms involved in the alteration of host behavior, in order to better utilize sick animal behavior as a strategy for diagnosis and treatment of disease. Methods: Rabbits were infested placing mites in the ear conduct. We characterized changes in exploratory behavior and scent marking evoked by acute (1-9 days) and chronic (25-33 days) experimental infestation. Behavior was recorded during ten minutes while the animals were in a 120 cm × 120 cm open field arena divided into 9 squares. Serum cortisol was measured individually using radioimmunoassay kits. Locomotor activity, chinning, rearing and body weight were compared using a Friedman test, the effect of treatment (infested versus non-infested) across time was analyzed using a repeated measures ANOVA, and the Pearson test was used to determine whether chinning and ambulation scores were significantly correlated. Serum cortisol levels and food consumption were analyzed with a Kruskal-Wallis test and body temperature was analyzed with an ANOVA test. Results: We observed a significant decrease in rearing behavior as early as two days post-infestation, while chinning and locomotor activity were significantly decreased four days post-infestation. Chronic infestation was associated with decreased food intake, significant weight loss, and a trend toward increased serum cortisol levels, while no changes were observed in body temperature. Conclusions: The presence of visible lesions within the ear canal is commonly used to detect mite infestation in rabbits, but this is possible only after chronic infestation. The behaviors described here may be a useful and economic tool in guiding the early diagnosis of parasitic infestation by P. cuniculi, allowing for early treatment and the application of control measures before significant weight loss occurs, thereby avoiding economic losses.
Journal of Cellular Biochemistry, 2003
In monocytes and macrophages, activation of the tyrosine kinase Syk is an essential step in the b... more In monocytes and macrophages, activation of the tyrosine kinase Syk is an essential step in the biochemical cascade linking aggregation of receptors for immunoglobulin G (FcgR) to initiation of effector functions. An increase in Syk activation during differentiation of myeloid cells by different agents has been reported. We studied the activation state of Syk in response to FcgRII crosslinking in monocytic cells before and after in vitro differentiation with 1a, 25-dihydroxy-vitamin D3. We show here that while in undifferentiated THP-1 cells clustering of FcgRII induces significant phosphorylation and activation of Syk, in THP-1 cells differentiated in vitro by 1a, 25-dihydroxy-vitamin D3, FcgRII crosslinking induced a decrease in Syk activity. In vitro differentiation did not induce changes in the expression of FcgRII isoforms. The observed effect on Syk activation though FcgRII could be mediated by differentiation-induced changes in the expression and basal activation level of Syk, as well as changes in the association of Syk with the tyrosine phosphatase SHP-1. These results suggest that the biochemical signaling pathways induced by FcgRII could be dependent on the differentiation state of the cell.
International Journal for Parasitology, 2002
Cysticercotic male mice undergo an impressive feminisation process, characterised by 200 times in... more Cysticercotic male mice undergo an impressive feminisation process, characterised by 200 times increased serum 17beta-estradiol levels while testosterone and dihydrotestosterone are 90% reduced, which results in elevated parasite burden. Administration of Fadrozole (an aromatase inhibitor) in male and female mice suppressed the production of 17beta-estradiol, accompanied with a 70% reduction in parasite burden. This protective effect was associated in male mice with a recovery of the specific cellular immune response. Interleukin-6 (IL-6) serum levels, and its production by splenocytes, was augmented by 80%, together with a 10-fold increase in its expression in testes of infected male mice. Fadrozole treatment returned these levels to baseline values. Aromatase expression in the testes of infected male mice was not affected by Fadrozole. These results suggest that aromatase and IL-6 are key molecules in the production of the feminisation undergone by infected male mice and to Fadrozole treatment as a possible new therapeutic approach to cysticercosis.
International Journal for Parasitology, 2003
Cytokines may regulate the function of the hypothalamic–pituitary–adrenal axis during schistosomi... more Cytokines may regulate the function of the hypothalamic–pituitary–adrenal axis during schistosomiasis. This possibility was investigated in baboons experimentally infected with Schistosoma mansoni. Serum levels of corticotrophin-releasing hormone, adrenocorticotrophin, cortisol and dehydroepiandrosterone were confirmed to be decreased in infected baboons as previously shown. To explore if this effect is associated with specific expression of cytokines with endocrine activity, and are also
Open …, 2010
Interleukin 6 (IL-6) is a typical pleiotropic cytokine that modulates a variety of physiological ... more Interleukin 6 (IL-6) is a typical pleiotropic cytokine that modulates a variety of physiological events in vertebrates, including cell proliferation, differentiation, survival, and apoptosis, among other functions. IL-6 plays roles in the immune, the endocrine, the nervous, and the hematopoietic systems, in bone metabolism, regulation of blood pressure and inflammation. IL-6 exerts its effects on different tissues and organ systems. Many cell types are reported to produce IL-6: T cells, B cells, polymorphonuclear cells, eosinophils, monocyte/macrophages, mast cells, dendritic cells, chondrocytes, osteoblasts, endothelial cells, skeletal and smooth muscle cells, islet cells, thyroid cells, fibroblasts, mesangial cells, keratinocytes, microglial cells, astrocytes, oligodendrocytes, adipose tissue and certain tumor cells. Here, we review the participation of the IL-6 in the neuroimmunoendocrine network. The specific targeting of the IL-6 pathway can be a promising new approach for the treatment and prevention of neurodegenerative disorders in humans as well as improving the autoinflammatory process both systemically and locally.
bq.unam.mx
Los receptores para el fragmento Fc de la IgG (FcRs) juegan un papel muy importante en la activa... more Los receptores para el fragmento Fc de la IgG (FcRs) juegan un papel muy importante en la activación de funciones efectoras celulares mediadas por anticuerpos IgG. Los FcR son una familia heterogénea de receptores que no muestran una selectividad absoluta por las distintas subclases de IgG. Los receptores FcR no poseen actividad intrinseca de cinasa, pero cuando son agregados por partículas opsonizadas o complejos antígeno-anticuerpo pueden desencadenar una cascada de señales bioquímicas que inicia por la activación de cinasas de tirosina de la familia Src, las cuales fosforilan residuos de tirosina en el receptor mismo o en cadenas asociadas a ellos. Estas tirosinas fosforiladas sirven de punto de anclaje y activación de la cinasa Syk. La cinasa Syk activada fosforila una variedad de sustratos intracelulares para la activación de las funciones efectoras. Aunque se conoce de manera general el mecanismo bioquímico por el cual los FcRs median la activación celular, y se han identificado un gran número de moléculas que intervienen en las vias de señalización intracelular que pueden ser activadas por la señalización a
Experimental …, 2002
The effects of testosterone, dihydrotestosterone, and 17β-estradiol in castrated mice of both sex... more The effects of testosterone, dihydrotestosterone, and 17β-estradiol in castrated mice of both sexes infected with Taenia crassiceps cysticerci were studied. The results showed that castration and treatment with either testosterone or dihydrotestosterone before infection decreased ...
Journal of …, 2001
The effects of in vitro treatment of cercariae, schistosomula, and adult worms of Schistosoma man... more The effects of in vitro treatment of cercariae, schistosomula, and adult worms of Schistosoma mansoni with 4 hypothalamicpituitaryadrenal (HPA) axis hormones are described. Dehydroepiandrosterone (DHEA) had the strongest effect on viability. Cercariae were more susceptible to this ...
Immunology Letters, 2005
Fcgamma receptor (FcgammaR)-mediated phagocytosis by mononuclear phagocytes is an essential funct... more Fcgamma receptor (FcgammaR)-mediated phagocytosis by mononuclear phagocytes is an essential function in host defense. This process is initiated by crosslinking of membrane FcgammaRs, which induces phosphorylation and activation of Src and Syk tyrosine kinases. Activation of these enzymes is essential for initiating the biochemical cascade that results in the cytoskeletal and membrane changes involved in phagocytosis. Phagocytic capacity and other effector functions of mononuclear phagocytes change during differentiation/maturation of these cells. This is a complex process governed by different soluble and micro-environmental factors, giving rise to populations of cells with distinct phenotypic characteristics. Several agents, including calcitriol, have been shown to induce in vitro differentiation-related phenotypic changes in monocytic cell lines. In this paper, we characterized the changes in the initial biochemical signals associated with the increase in FcgammaR-mediated phagocytosis induced by calcitriol in monocytic U-937 cells. The 10-fold increase in phagocytic capacity is not accompanied by an increase in FcgammaR expression. However, the phosphorylation levels of Lyn and Syk after FcgammaRI or FcgammaRII crosslinking are increased after calcitriol treatment. Our results suggest that signaling induced by FcgammaR in mononuclear phagocytes is not only dependent on the quantity of FcgammaRs aggregated by a stimulus, but it is highly dependent on the cell&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s differentiation state.
Los receptores para el fragmento Fc de la IgG (FcRs) juegan un papel muy importante en la activa... more Los receptores para el fragmento Fc de la IgG (FcRs) juegan un papel muy importante en la activación de funciones efectoras celulares mediadas por anticuerpos IgG. Los FcR son una familia heterogénea de receptores que no muestran una selectividad absoluta por las distintas subclases de IgG. Los receptores FcR no poseen actividad intrinseca de cinasa, pero cuando son agregados por partículas opsonizadas o complejos antígeno-anticuerpo pueden desencadenar una cascada de señales bioquímicas que inicia por la activación de cinasas de tirosina de la familia Src, las cuales fosforilan residuos de tirosina en el receptor mismo o en cadenas asociadas a ellos. Estas tirosinas fosforiladas sirven de punto de anclaje y activación de la cinasa Syk. La cinasa Syk activada fosforila una variedad de sustratos intracelulares para la activación de las funciones efectoras. Aunque se conoce de manera general el mecanismo bioquímico por el cual los FcRs median la activación celular, y se han identificado un gran número de moléculas que intervienen en las vias de señalización intracelular que pueden ser activadas por la señalización a traves de FcRs, queda por determinar la influencia de diferentes factores (de la estructura del agregado, del estado de activacion de la célula, de las isoformas de FcRs expresadas, etc) sobre este mecanismo y por lo tanto sobre la respuesta celular.
In monocytes and macrophages, activation of the tyrosine kinase Syk is an essential step in the b... more In monocytes and macrophages, activation of the tyrosine kinase Syk is an essential step in the biochemical cascade linking aggregation of receptors for immunoglobulin G (FcgammaR) to initiation of effector functions. An increase in Syk activation during differentiation of myeloid cells by different agents has been reported. We studied the activation state of Syk in response to FcgammaRII crosslinking in monocytic cells before and after in vitro differentiation with 1alpha, 25-dihydroxy-vitamin D3. We show here that while in undifferentiated THP-1 cells clustering of FcgammaRII induces significant phosphorylation and activation of Syk, in THP-1 cells differentiated in vitro by 1alpha, 25-dihydroxy-vitamin D3, FcgammaRII crosslinking induced a decrease in Syk activity. In vitro differentiation did not induce changes in the expression of FcgammaRII isoforms. The observed effect on Syk activation though FcgammaRII could be mediated by differentiation-induced changes in the expression a...
Immunology letters, 2005
Fcγ receptor (FcγR)-mediated phagocytosis by mononuclear phagocytes is an essential function in h... more Fcγ receptor (FcγR)-mediated phagocytosis by mononuclear phagocytes is an essential function in host defense. This process is initiated by crosslinking of membrane FcγRs, which induces phosphorylation and activation of Src and Syk tyrosine kinases. Activation of these ...
International Journal of Morphology, 2013
The purpose of this study was to analyze the macroscopic morphometry of the ovaries, uterus and v... more The purpose of this study was to analyze the macroscopic morphometry of the ovaries, uterus and vagina in rabbit does in the first, second and third parturition at 24 hours post-weaning in order to determine if there are differences between parturitions. Weaning of the litter was performed at 30 days post-partum and 24 hours later the does were euthanized. Right and left ovaries, uterine horns-cervix and vagina were removed, and the length of each one was measured. Significant differences were found in the average of the right ovary length between the first group with respect to second and third parturition group (P ≤ 0.05 and P ≤ 0.01). Also, left ovary length was different between the first and second with respect to third parturition group (P <0.001). Average total ovary length increased significantly as the number of parturitions increased in second and third parturition groups (P ≤ 0.01 and P≤0.001). The weight of the left and right ovaries was higher in does in their second and third parturition when compared to those in their first (P≤ 0.5; P≤ 0.01). The average total ovary weight increased significantly as the number of parturitions in second and third parturition groups (P≤0.001). The length of the left and right uterine horn-cervix of the rabbits after second and third parturition decreased when compared to that of females in their first parturition (P≤ 0.05; P≤0.001). The average total uterine horns-cervix length decreased significantly as the number of parturitions in second and third parturition groups (P≤0.001). Furthermore, vagina length in females in their third parturition was greater than that of first and second parturition (P≤ 0.01).The color of the vulva of the majority of females in their first parturition (3/4) was pale pink while. In contrast, the majority of females in their second parturition (3/4) had their vulva intensely red. All of the females (4/4) in the third parturition group had their vulva intensely red. We conclude that in female rabbits the macroscopic morphometric characteristics of ovaries, uterus and vagina, at 24 hours post-weaning vary according to the number of parturitions.
BioMed Research International, 2013
Bacillus thuringiensisis a gram-positive soil-dwelling bacterium that is commonly used as a biolo... more Bacillus thuringiensisis a gram-positive soil-dwelling bacterium that is commonly used as a biological pesticide. This bacterium may also be used for biological control of helminth parasites in domestic animals. In this study, we evaluated the possible ovicidal and cestocidal effects of a total protein extract ofB. thuringiensisnative strains on the zoonotic cestode parasite of dogs,Dipylidium caninum(D. caninum). Dose and time response curves were determined by coincubatingB. thuringiensisproteins at concentration ranging from 100 to 1000 μg/mL along with 4000 egg capsules ofD. caninum. Egg viability was evaluated using the trypan blue exclusion test. The lethal concentration of toxins on eggs was 600 μg/ml, and the best incubation time to produce this effect was 3 h. In the adult stage, the motility and the thickness of the tegument were used as indicators of damage. The motility was inhibited by 100% after 8 hours of culture compared to the control group, while the thickness of t...
Parasites & Vectors, 2013
Background: Parasitic diseases are important in animal production because they cause high economi... more Background: Parasitic diseases are important in animal production because they cause high economic losses. Affected animals often exhibit stereotypical behavioral alterations such as anorexia and inactivity, among others. Among the diseases that commonly affect domestic rabbits is mange, which is caused by the mite Psoroptes cuniculi. Therefore, within the context of the host-parasite relationship, it is critical to understand the mechanisms involved in the alteration of host behavior, in order to better utilize sick animal behavior as a strategy for diagnosis and treatment of disease. Methods: Rabbits were infested placing mites in the ear conduct. We characterized changes in exploratory behavior and scent marking evoked by acute (1-9 days) and chronic (25-33 days) experimental infestation. Behavior was recorded during ten minutes while the animals were in a 120 cm × 120 cm open field arena divided into 9 squares. Serum cortisol was measured individually using radioimmunoassay kits. Locomotor activity, chinning, rearing and body weight were compared using a Friedman test, the effect of treatment (infested versus non-infested) across time was analyzed using a repeated measures ANOVA, and the Pearson test was used to determine whether chinning and ambulation scores were significantly correlated. Serum cortisol levels and food consumption were analyzed with a Kruskal-Wallis test and body temperature was analyzed with an ANOVA test. Results: We observed a significant decrease in rearing behavior as early as two days post-infestation, while chinning and locomotor activity were significantly decreased four days post-infestation. Chronic infestation was associated with decreased food intake, significant weight loss, and a trend toward increased serum cortisol levels, while no changes were observed in body temperature. Conclusions: The presence of visible lesions within the ear canal is commonly used to detect mite infestation in rabbits, but this is possible only after chronic infestation. The behaviors described here may be a useful and economic tool in guiding the early diagnosis of parasitic infestation by P. cuniculi, allowing for early treatment and the application of control measures before significant weight loss occurs, thereby avoiding economic losses.
Journal of Cellular Biochemistry, 2003
In monocytes and macrophages, activation of the tyrosine kinase Syk is an essential step in the b... more In monocytes and macrophages, activation of the tyrosine kinase Syk is an essential step in the biochemical cascade linking aggregation of receptors for immunoglobulin G (FcgR) to initiation of effector functions. An increase in Syk activation during differentiation of myeloid cells by different agents has been reported. We studied the activation state of Syk in response to FcgRII crosslinking in monocytic cells before and after in vitro differentiation with 1a, 25-dihydroxy-vitamin D3. We show here that while in undifferentiated THP-1 cells clustering of FcgRII induces significant phosphorylation and activation of Syk, in THP-1 cells differentiated in vitro by 1a, 25-dihydroxy-vitamin D3, FcgRII crosslinking induced a decrease in Syk activity. In vitro differentiation did not induce changes in the expression of FcgRII isoforms. The observed effect on Syk activation though FcgRII could be mediated by differentiation-induced changes in the expression and basal activation level of Syk, as well as changes in the association of Syk with the tyrosine phosphatase SHP-1. These results suggest that the biochemical signaling pathways induced by FcgRII could be dependent on the differentiation state of the cell.
International Journal for Parasitology, 2002
Cysticercotic male mice undergo an impressive feminisation process, characterised by 200 times in... more Cysticercotic male mice undergo an impressive feminisation process, characterised by 200 times increased serum 17beta-estradiol levels while testosterone and dihydrotestosterone are 90% reduced, which results in elevated parasite burden. Administration of Fadrozole (an aromatase inhibitor) in male and female mice suppressed the production of 17beta-estradiol, accompanied with a 70% reduction in parasite burden. This protective effect was associated in male mice with a recovery of the specific cellular immune response. Interleukin-6 (IL-6) serum levels, and its production by splenocytes, was augmented by 80%, together with a 10-fold increase in its expression in testes of infected male mice. Fadrozole treatment returned these levels to baseline values. Aromatase expression in the testes of infected male mice was not affected by Fadrozole. These results suggest that aromatase and IL-6 are key molecules in the production of the feminisation undergone by infected male mice and to Fadrozole treatment as a possible new therapeutic approach to cysticercosis.
International Journal for Parasitology, 2003
Cytokines may regulate the function of the hypothalamic–pituitary–adrenal axis during schistosomi... more Cytokines may regulate the function of the hypothalamic–pituitary–adrenal axis during schistosomiasis. This possibility was investigated in baboons experimentally infected with Schistosoma mansoni. Serum levels of corticotrophin-releasing hormone, adrenocorticotrophin, cortisol and dehydroepiandrosterone were confirmed to be decreased in infected baboons as previously shown. To explore if this effect is associated with specific expression of cytokines with endocrine activity, and are also
Open …, 2010
Interleukin 6 (IL-6) is a typical pleiotropic cytokine that modulates a variety of physiological ... more Interleukin 6 (IL-6) is a typical pleiotropic cytokine that modulates a variety of physiological events in vertebrates, including cell proliferation, differentiation, survival, and apoptosis, among other functions. IL-6 plays roles in the immune, the endocrine, the nervous, and the hematopoietic systems, in bone metabolism, regulation of blood pressure and inflammation. IL-6 exerts its effects on different tissues and organ systems. Many cell types are reported to produce IL-6: T cells, B cells, polymorphonuclear cells, eosinophils, monocyte/macrophages, mast cells, dendritic cells, chondrocytes, osteoblasts, endothelial cells, skeletal and smooth muscle cells, islet cells, thyroid cells, fibroblasts, mesangial cells, keratinocytes, microglial cells, astrocytes, oligodendrocytes, adipose tissue and certain tumor cells. Here, we review the participation of the IL-6 in the neuroimmunoendocrine network. The specific targeting of the IL-6 pathway can be a promising new approach for the treatment and prevention of neurodegenerative disorders in humans as well as improving the autoinflammatory process both systemically and locally.
bq.unam.mx
Los receptores para el fragmento Fc de la IgG (FcRs) juegan un papel muy importante en la activa... more Los receptores para el fragmento Fc de la IgG (FcRs) juegan un papel muy importante en la activación de funciones efectoras celulares mediadas por anticuerpos IgG. Los FcR son una familia heterogénea de receptores que no muestran una selectividad absoluta por las distintas subclases de IgG. Los receptores FcR no poseen actividad intrinseca de cinasa, pero cuando son agregados por partículas opsonizadas o complejos antígeno-anticuerpo pueden desencadenar una cascada de señales bioquímicas que inicia por la activación de cinasas de tirosina de la familia Src, las cuales fosforilan residuos de tirosina en el receptor mismo o en cadenas asociadas a ellos. Estas tirosinas fosforiladas sirven de punto de anclaje y activación de la cinasa Syk. La cinasa Syk activada fosforila una variedad de sustratos intracelulares para la activación de las funciones efectoras. Aunque se conoce de manera general el mecanismo bioquímico por el cual los FcRs median la activación celular, y se han identificado un gran número de moléculas que intervienen en las vias de señalización intracelular que pueden ser activadas por la señalización a
Experimental …, 2002
The effects of testosterone, dihydrotestosterone, and 17β-estradiol in castrated mice of both sex... more The effects of testosterone, dihydrotestosterone, and 17β-estradiol in castrated mice of both sexes infected with Taenia crassiceps cysticerci were studied. The results showed that castration and treatment with either testosterone or dihydrotestosterone before infection decreased ...
Journal of …, 2001
The effects of in vitro treatment of cercariae, schistosomula, and adult worms of Schistosoma man... more The effects of in vitro treatment of cercariae, schistosomula, and adult worms of Schistosoma mansoni with 4 hypothalamicpituitaryadrenal (HPA) axis hormones are described. Dehydroepiandrosterone (DHEA) had the strongest effect on viability. Cercariae were more susceptible to this ...
Immunology Letters, 2005
Fcgamma receptor (FcgammaR)-mediated phagocytosis by mononuclear phagocytes is an essential funct... more Fcgamma receptor (FcgammaR)-mediated phagocytosis by mononuclear phagocytes is an essential function in host defense. This process is initiated by crosslinking of membrane FcgammaRs, which induces phosphorylation and activation of Src and Syk tyrosine kinases. Activation of these enzymes is essential for initiating the biochemical cascade that results in the cytoskeletal and membrane changes involved in phagocytosis. Phagocytic capacity and other effector functions of mononuclear phagocytes change during differentiation/maturation of these cells. This is a complex process governed by different soluble and micro-environmental factors, giving rise to populations of cells with distinct phenotypic characteristics. Several agents, including calcitriol, have been shown to induce in vitro differentiation-related phenotypic changes in monocytic cell lines. In this paper, we characterized the changes in the initial biochemical signals associated with the increase in FcgammaR-mediated phagocytosis induced by calcitriol in monocytic U-937 cells. The 10-fold increase in phagocytic capacity is not accompanied by an increase in FcgammaR expression. However, the phosphorylation levels of Lyn and Syk after FcgammaRI or FcgammaRII crosslinking are increased after calcitriol treatment. Our results suggest that signaling induced by FcgammaR in mononuclear phagocytes is not only dependent on the quantity of FcgammaRs aggregated by a stimulus, but it is highly dependent on the cell&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s differentiation state.
Los receptores para el fragmento Fc de la IgG (FcRs) juegan un papel muy importante en la activa... more Los receptores para el fragmento Fc de la IgG (FcRs) juegan un papel muy importante en la activación de funciones efectoras celulares mediadas por anticuerpos IgG. Los FcR son una familia heterogénea de receptores que no muestran una selectividad absoluta por las distintas subclases de IgG. Los receptores FcR no poseen actividad intrinseca de cinasa, pero cuando son agregados por partículas opsonizadas o complejos antígeno-anticuerpo pueden desencadenar una cascada de señales bioquímicas que inicia por la activación de cinasas de tirosina de la familia Src, las cuales fosforilan residuos de tirosina en el receptor mismo o en cadenas asociadas a ellos. Estas tirosinas fosforiladas sirven de punto de anclaje y activación de la cinasa Syk. La cinasa Syk activada fosforila una variedad de sustratos intracelulares para la activación de las funciones efectoras. Aunque se conoce de manera general el mecanismo bioquímico por el cual los FcRs median la activación celular, y se han identificado un gran número de moléculas que intervienen en las vias de señalización intracelular que pueden ser activadas por la señalización a traves de FcRs, queda por determinar la influencia de diferentes factores (de la estructura del agregado, del estado de activacion de la célula, de las isoformas de FcRs expresadas, etc) sobre este mecanismo y por lo tanto sobre la respuesta celular.