Israel Espinosa - Academia.edu (original) (raw)

Uploads

Papers by Israel Espinosa

Research paper thumbnail of Strategies of the protozoan parasite Entamoeba histolytica to evade the innate immune responses of intestinal epithelial cells

Journal of Biosciences, 2002

Molecules expressed by the pathogenic ameobaEntamoeba histolytica but weakly expressed or absent ... more Molecules expressed by the pathogenic ameobaEntamoeba histolytica but weakly expressed or absent from the non-pathogenic ameobaEntamoeba dispar could be used by intestinal epithelial cells to discriminate between the two species and to initiate an appropriate inflammatory response. Among the possible molecules involved in this identification are the Gal/GalNac lectin and the lipophosphoglycan. Once the inflammatory response is initiated,E. histolytica trophozoites have to protect themselves against reactive nitrogen intermediates produced by intestinal epithelial cells, oxygen intermediates, and cytotoxic molecules released by activated neutrophils. By screening theE. histolytica genome, we have identified proteins that may play a role in the defence strategy of the parasite. One of these proteins, a serine proteinase inhibitor, inhibits human neutrophil cathepsin G, a key component of the host defence.

Research paper thumbnail of An Integrated Health Risk Assessment Approach to the Study of Mining Sites Contaminated With Arsenic and Lead

Integrated Environmental Assessment and Management, 2007

In order to test the value of an integrated approach for the analysis of health risks at contamin... more In order to test the value of an integrated approach for the analysis of health risks at contaminated sites, an integrated health risk assessment in a mining area was performed following 3 steps: 1) Environmental monitoring of surface soil, 2) assessment of exposure to metals in children and native rodents, and 3) DNA damage evaluation (comet assay) in children and rodents. These aspects also were studied in less exposed populations. Our results in humans showed that children living in the most polluted area (Villa de la Paz, Mexico) had higher lead blood concentrations (geometric mean of 13.8 lg/dL) and urinary arsenic levels (geometric mean of 52.1 lg/g creatinine) compared to children living in a control area (Matehuala, Mexico; blood lead of 7.3 lg/dL; urinary arsenic of 16.8 lg/g creatinine). Furthermore, the exposed children also had increased DNA damage (tail moment mean in Villa de la Paz of 4.8 vs 3.9 in Matehuala; p , 0.05). Results in rodents were identical. Animals captured in the polluted area had higher levels of arsenic (geometric mean of 1.3 lg/g in liver and 1.8 lg/g in kidney), lead (0.2 lg/g in liver and 0.9 lg/g in kidney), and cadmium (0.8 lg/g in liver and 2.2 lg/g in kidney), and increased DNA damage (tail moment mean of 18.2) when compared to control animals (arsenic in liver of 0.08 lg/g and kidney of 0.1 lg/g; lead in liver of 0.06 lg/g and kidney of 0.3 lg/g; cadmium in liver of 0.06 lg/g and kidney of 0.6 lg/g; and tail moment of 14.2). With the data in children and rodents, the weight-of-evidence for health risks (in this case DNA damage) associated with metal exposure in Villa de la Paz was strengthened. Therefore, a remediation program was easier to justify, and a feasibility study at this site is under way.

Research paper thumbnail of Entamoeba histolytica Expressing a Dominant Negative N-Truncated Light Subunit of Its Gal-Lectin Are Less Virulent

Molecular Biology of The Cell, 2002

The 260-kDa heterodimeric Gal/GalNAc-specific Lectin (Gal-lectin) of Entamoeba histolytica dissoc... more The 260-kDa heterodimeric Gal/GalNAc-specific Lectin (Gal-lectin) of Entamoeba histolytica dissociates under reducing conditions into a heavy (hgl, 170 kDa) and a light subunit (lgl, 35 kDa). We have previously shown that inhibition of expression of the 35-kDa subunit by antisense RNA causes a decrease in virulence. To further understand the role of the light subunit of the Gal-lectin in pathogenesis, amoebae were transfected with plasmids encoding intact, mutated, and truncated forms of the light subunit lgl1 gene. A transfectant in which the 55 N-terminal amino acids of the lgl were removed, overproduced an N-truncated lgl protein (32 kDa), which replaced most of the native 35-kDa lgl in the formation of the Gal-lectin heterodimeric complex and exerted a dominant negative effect. Amoebae transfected with this construct showed a significant decrease in their ability to adhere to and kill mammalian cells as well as in their capacity to form rosettes with and to phagocytose erythrocytes. In addition, immunofluorescence confocal microscopy of this transfectant with anti-Gal-lectin antibodies showed an impaired ability to cap. These results indicate that the light subunit has a role in enabling the clustering of Gal-lectin complexes and that its N-truncation affects this function, which is required for virulence.

Research paper thumbnail of Locating seismic-sense stations through genetic algorithm: genetic algorithms

ESCRITURA Presenta disposición en actividades de escritura, así mismo se requiere poner mayor énf... more ESCRITURA Presenta disposición en actividades de escritura, así mismo se requiere poner mayor énfasis en la corrección de textos.

Research paper thumbnail of RECOMENDACIONES DE REPORTES DE EVALUACION

ESCRITURA Presenta disposición en actividades de escritura, así mismo se requiere poner mayor énf... more ESCRITURA Presenta disposición en actividades de escritura, así mismo se requiere poner mayor énfasis en la corrección de textos.

Research paper thumbnail of Strategies of the protozoan parasite Entamoeba histolytica to evade the innate immune responses of intestinal epithelial cells

Journal of Biosciences, 2002

Molecules expressed by the pathogenic ameobaEntamoeba histolytica but weakly expressed or absent ... more Molecules expressed by the pathogenic ameobaEntamoeba histolytica but weakly expressed or absent from the non-pathogenic ameobaEntamoeba dispar could be used by intestinal epithelial cells to discriminate between the two species and to initiate an appropriate inflammatory response. Among the possible molecules involved in this identification are the Gal/GalNac lectin and the lipophosphoglycan. Once the inflammatory response is initiated,E. histolytica trophozoites have to protect themselves against reactive nitrogen intermediates produced by intestinal epithelial cells, oxygen intermediates, and cytotoxic molecules released by activated neutrophils. By screening theE. histolytica genome, we have identified proteins that may play a role in the defence strategy of the parasite. One of these proteins, a serine proteinase inhibitor, inhibits human neutrophil cathepsin G, a key component of the host defence.

Research paper thumbnail of An Integrated Health Risk Assessment Approach to the Study of Mining Sites Contaminated With Arsenic and Lead

Integrated Environmental Assessment and Management, 2007

In order to test the value of an integrated approach for the analysis of health risks at contamin... more In order to test the value of an integrated approach for the analysis of health risks at contaminated sites, an integrated health risk assessment in a mining area was performed following 3 steps: 1) Environmental monitoring of surface soil, 2) assessment of exposure to metals in children and native rodents, and 3) DNA damage evaluation (comet assay) in children and rodents. These aspects also were studied in less exposed populations. Our results in humans showed that children living in the most polluted area (Villa de la Paz, Mexico) had higher lead blood concentrations (geometric mean of 13.8 lg/dL) and urinary arsenic levels (geometric mean of 52.1 lg/g creatinine) compared to children living in a control area (Matehuala, Mexico; blood lead of 7.3 lg/dL; urinary arsenic of 16.8 lg/g creatinine). Furthermore, the exposed children also had increased DNA damage (tail moment mean in Villa de la Paz of 4.8 vs 3.9 in Matehuala; p , 0.05). Results in rodents were identical. Animals captured in the polluted area had higher levels of arsenic (geometric mean of 1.3 lg/g in liver and 1.8 lg/g in kidney), lead (0.2 lg/g in liver and 0.9 lg/g in kidney), and cadmium (0.8 lg/g in liver and 2.2 lg/g in kidney), and increased DNA damage (tail moment mean of 18.2) when compared to control animals (arsenic in liver of 0.08 lg/g and kidney of 0.1 lg/g; lead in liver of 0.06 lg/g and kidney of 0.3 lg/g; cadmium in liver of 0.06 lg/g and kidney of 0.6 lg/g; and tail moment of 14.2). With the data in children and rodents, the weight-of-evidence for health risks (in this case DNA damage) associated with metal exposure in Villa de la Paz was strengthened. Therefore, a remediation program was easier to justify, and a feasibility study at this site is under way.

Research paper thumbnail of Entamoeba histolytica Expressing a Dominant Negative N-Truncated Light Subunit of Its Gal-Lectin Are Less Virulent

Molecular Biology of The Cell, 2002

The 260-kDa heterodimeric Gal/GalNAc-specific Lectin (Gal-lectin) of Entamoeba histolytica dissoc... more The 260-kDa heterodimeric Gal/GalNAc-specific Lectin (Gal-lectin) of Entamoeba histolytica dissociates under reducing conditions into a heavy (hgl, 170 kDa) and a light subunit (lgl, 35 kDa). We have previously shown that inhibition of expression of the 35-kDa subunit by antisense RNA causes a decrease in virulence. To further understand the role of the light subunit of the Gal-lectin in pathogenesis, amoebae were transfected with plasmids encoding intact, mutated, and truncated forms of the light subunit lgl1 gene. A transfectant in which the 55 N-terminal amino acids of the lgl were removed, overproduced an N-truncated lgl protein (32 kDa), which replaced most of the native 35-kDa lgl in the formation of the Gal-lectin heterodimeric complex and exerted a dominant negative effect. Amoebae transfected with this construct showed a significant decrease in their ability to adhere to and kill mammalian cells as well as in their capacity to form rosettes with and to phagocytose erythrocytes. In addition, immunofluorescence confocal microscopy of this transfectant with anti-Gal-lectin antibodies showed an impaired ability to cap. These results indicate that the light subunit has a role in enabling the clustering of Gal-lectin complexes and that its N-truncation affects this function, which is required for virulence.

Research paper thumbnail of Locating seismic-sense stations through genetic algorithm: genetic algorithms

ESCRITURA Presenta disposición en actividades de escritura, así mismo se requiere poner mayor énf... more ESCRITURA Presenta disposición en actividades de escritura, así mismo se requiere poner mayor énfasis en la corrección de textos.

Research paper thumbnail of RECOMENDACIONES DE REPORTES DE EVALUACION

ESCRITURA Presenta disposición en actividades de escritura, así mismo se requiere poner mayor énf... more ESCRITURA Presenta disposición en actividades de escritura, así mismo se requiere poner mayor énfasis en la corrección de textos.