Maria Sanchez | La Universidad del Zulia (original) (raw)
Papers by Maria Sanchez
Psychophysiology, 2009
This study examines similarities and differences in fear potentiation between two protective refl... more This study examines similarities and differences in fear potentiation between two protective reflexes: cardiac defense and eyeblink startle. Women reporting intense fear of animals but low fear of blood or intense fear of blood but low fear of animals viewed pictures depicting blood or the feared animal for 6 s in 2 separate trials in counterbalanced order. An intense burst of white noise, able to elicit both a cardiac defense response and a reflexive startle blink, was presented 3.5 s after picture onset. Both cardiac and blink responses were potentiated when highly fearful individuals viewed fearful pictures. However, differences appeared concerning picture order. This pattern of results indicates communalities and differences among protective reflexes that are relevant for understanding the dynamics of emotional reflex modulation.
Gerokomos, 2007
ABSTRACT Introducción y objetivo: En el ámbito de las residencias de mayores es importante tener ... more ABSTRACT Introducción y objetivo: En el ámbito de las residencias de mayores es importante tener una visión integral del anciano y del envejecimiento activo para retardar la dependencia y potenciar la capacidad funcional y la autonomía. Partiendo de un abordaje interdisciplinar, nos planteamos elaborar un instrumento de valoración enfermera, basado en el modelo conceptual de Virginia Henderson y complementado con cuestionarios y escalas validadas, que nos permita detectar las necesidades del anciano, ponderar el riesgo de aparición de síndromes geriátricos y planificar los cuidados correspondientes. Método: Creación de grupo de trabajo, establecimiento de objetivos por consenso, revisión bibliográfica, desarrollo de criterios de elaboración, coordinación con el resto del equipo y validación del documento. Resultados: Obtenemos una hoja de valoración de enfermería para mayores institucionalizados en residencias, de 8 páginas, con ítems abiertos y cerrados, basada en el modelo de las 14 necesidades de Virginia Henderson y apoyada por nueve escalas de valoración, con su correspondiente guía de cumplimentación. Conclusiones: El tiempo empleado en la valoración enfermera geriátrica es una inversión necesaria para asegurar una asistencia adecuada y de calidad, ya que supone una herramienta de trabajo útil para enfermería y para el resto del equipo multidisciplinar del centro, al permitir individualizar los cuidados, cuantificar las incapacidades y proporcionar el nivel asistencial más adecuado a cada residente.
En la presente investigación se persigue la finalidad de valorar económicamente los recursos natu... more En la presente investigación se persigue la finalidad de valorar económicamente los recursos naturales del Parque Nacional Viñales de Cuba (PNV) en concordancia con el potencial turístico existente. La valoración se llevó a cabo a través de la aplicación combinada de varias técnicas, se analizan los factores externos e internos que muestran la situación predominante del producto ecoturístico y posteriormente se aplica el método de valoración contingente para la valoración económica de los bienes y servicios ambientales más representativos en las prácticas turísticas.
Journal of Wine Research, 2008
In an extremely competitive international market in which consumption is undergoing a period of s... more In an extremely competitive international market in which consumption is undergoing a period of stagnation, it is essential for businesses to develop and implement adequate control systems to help them deal with these circumstances. Cost management should provide relevant information to help grape-growers make better decisions and should even provide information for planning, control, and performance measurement. With this objective
Journal of Wine Research, 2010
Acceso de usuarios registrados. Acceso de usuarios registrados Usuario Contraseña. ...
Reumatología Clínica, 2012
Aquaculture Research, 2008
Journal of Molecular Spectroscopy, 2010
The diode laser absorption infrared spectrum of fluorobenzene has been recorded near 1230 cm À1 a... more The diode laser absorption infrared spectrum of fluorobenzene has been recorded near 1230 cm À1 after cooling the molecules in a supersonic pulsed jet. Spectral lines have been assigned to the m 7a fundamental band. Transitions of J between 32 and 49 have been recorded, that show characteristic line groupings in the P branch. Analysis of the spectrum gives the vibrational band origin and rotational and centrifugal distortion constants of the molecule in the m 7a = 1 state.
Canadian Journal of Chemistry, 2005
Page 1. The mechanisms of hydrolysis of alkyl N-alkylthioncarbamate esters at 100 °C1 Eduardo Hum... more Page 1. The mechanisms of hydrolysis of alkyl N-alkylthioncarbamate esters at 100 °C1 Eduardo Humeres, Maria de Nazaré M. Sanchez, Conceição ML Lobato, Nito A. Debacher, and Eduardo P. de Souza Abstract: The hydrolysis ...
Puerto Rico health sciences journal, 2013
The increasing demand for organ transplants exceeds the organ donation rate. Addressing this disc... more The increasing demand for organ transplants exceeds the organ donation rate. Addressing this discrepancy is challenging for organ procurement agencies and health professionals involved in the care of patients in dire need of organs. Research suggests that health-care professionals' knowledge of, attitudes toward, and behavior in terms of organ donation and transplantation are deciding variables in promoting organ donation. In Puerto Rico, there is a lack of information regarding medical student's knowledge of and/or attitudes toward organ donation, a lack that our study was designed to address. Two hundred thirty participants (98 first-year, 45 second-year, and 87 third-year medical students) completed a questionnaire consisting of 55 questions; 10 questions assessed knowledge and 20, attitudes about organ and tissue donation. The remaining questions inquired after demographic information, history of blood donation, and educational experience. In terms of their knowledge abo...
To compare the correlation between the departure areas (DA), negative or positive, in patients wh... more To compare the correlation between the departure areas (DA), negative or positive, in patients whose electrocardiogram showed left bundle branch block (LBBB) and association with left ventricular hipertrophy (LVH) and myocardial infarction (MI), to the electrocardiographic (ECG) and vectocardiographic (VCG) classic criteria. Methods -The study was carried out with 46 patients (27 males) with LBBB. These patients had hypertension (19.5%), coronary heart disease (34.7%) and 21 patients with no heart disease (45.8%). Results -The statistic analysis using the Cluster method divided the patients in two groups. Group I (22 patients) showed an average rate for the DA (-2 SD) of 1091 for QRS and of 640 for ST-T. For the DA (+2 SD), the average rate was 618 for QRS and 881 for ST-T; group II (24 patients) showed an averaged for the DA (-2 SD) of 1063 for QRS and of 225 for ST-T. For the DA (+2 SD), the averaged rate was 428 for QRS and 600 for ST-T. Conclusion -In general the current ECG/VCG findings, can not differentiate the presence of the association of LBBB to LVH and MI. The DA of ST-T, mainly negative was the most efficient to separate the two groups and help in the diferential diagnosis.
Fungi associated to postbloom fruit drop of Tahiti lime (Citrus latifolia Tan.) and evaluation of... more Fungi associated to postbloom fruit drop of Tahiti lime (Citrus latifolia Tan.) and evaluation of their chemical control Tahiti lime is an important crop with high economic potential in Monagas State, Venezuela. The incidence of diseases negatively affects crop yields, causing among other symptoms, postbloom fruit drop. In 2003 a trial was conducted in a commercial citrus orchard and four
Gastroenterología y Hepatología, 2008
2008;31(2):75-8 75
Rev Fed Arg …, 2005
La enfermedad coronaria es una de las principales causas de muerte en mujeres en los países desar... more La enfermedad coronaria es una de las principales causas de muerte en mujeres en los países desarro- llados a pesar de lo cual el diagnóstico no invasivo de esta patología en estas pacientes continúa siendo un tema controvertido. La información disponible para su valoración deriva de protocolos clínicos don- de la mayoría de la población son varones. En el presente
Neuropharmacology, 2015
Impact to the head or rapid head acceleration-deceleration can cause traumatic brain injury (TBI)... more Impact to the head or rapid head acceleration-deceleration can cause traumatic brain injury (TBI) with a characteristic pathology of traumatic axonal injury (TAI) and secondary damage in white matter tracts. Myelin and oligodendrocyte lineage cells have significant roles in the progression of white matter pathology after TBI and in the potential for plasticity and subsequent recovery. The myelination pattern of specific brain regions, such as frontal cortex, may also increase susceptibility to neurodegeneration and psychiatric symptoms after TBI. White matter pathology after TBI depends on the extent and distribution of axon damage, microhemorrhages and/or neuroinflammation. TAI occurs in a pattern of damaged axons dispersed among intact axons in white matter tracts. TAI accompanied by bleeding and/or inflammation produces focal regions of overt tissue destruction, resulting in loss of both axons and myelin. White matter regions with TAI may also exhibit demyelination of intact axons. Demyelinated axons that remain viable have the potential for remyelination and recovery of function. Indeed, animal models of TBI have demonstrated demyelination that is associated with evidence of remyelination, including oligodendrocyte progenitor cell proliferation, generation of new oligodendrocytes, and formation of thinner myelin. Changes in neuronal activity that accompany TBI may also involve myelin remodeling, which modifies conduction efficiency along intact myelinated fibers. Thus, effective remyelination and myelin remodeling may be neurobiological substrates of plasticity in neuronal circuits that require long-distance communication. This perspective integrates findings from multiple contexts to propose a model of myelin and oligodendrocyte lineage cell relevance in white matter injury after TBI.
Spectrochimica Acta Part B: Atomic Spectroscopy, 1997
A study is presented of the effects of the processes of redeposition of atomic vapor on the Arrhe... more A study is presented of the effects of the processes of redeposition of atomic vapor on the Arrhenius plots. For that purpose, a kinetic model that considers the redeposition of the initial atomic vapor, and the revaporization of the redeposited species, at a later time is proposed and tested for the electrothermal atomization of Cu. This model predicts Arrhenius plots which present negative deviations from the linear behavior expected for a single process of release and dissipation of the atomic vapor. The magnitude of the negative deviation increases as the readsorption rate and the temperature difference between the release and redeposition sites increase. This type of behavior is observed in the Arrhenius plots obtained when well used graphite tubes and ascorbic acid are employed for the atomization of Cu. However, when new pyrolytically coated graphite tubes, or tungstencoated tubes, are used, the Arrhenius plots show the expected linear behavior for the one-precursor model, with a first kinetic order of release. Additionally, when using Mo and Pd as modifiers, these plots shows two well defined slopes, which are characteristic of a two-precursor atomization mechanism. The experimental results indicate that the degree of vapor redeposition is determined not only by temperature gradients but also by the properties of the atomizer surface. © 1997 Elsevier Science B.V.
Investigative ophthalmology & visual science, 2015
In ischemic proliferative retinopathies, Müller glial cells (MGCs) acquire migratory abilities. H... more In ischemic proliferative retinopathies, Müller glial cells (MGCs) acquire migratory abilities. However, the mechanisms that regulate this migration remain poorly understood. In addition, proliferative disorders associated with enhanced activities of matrix metalloproteinases (MMPs) also involve insulin-like growth factor (IGF)-1 participation. Therefore, the main interest of this work was to investigate the IGF-1 effect on the extracellular proteolytic activity in MGCs. Cell culture supernatants and cell lysates of the human MGC line MIO-M1 stimulated with IGF-1 were analyzed for MMP-2 by zymographic and Western blot analysis. The MGCs' motility was evaluated by scratch wound assay. The MMP-2, β1-integrin, and focal adhesions were detected by confocal microscopy. The localization of active MMPs and actin cytoskeleton were evaluated by in situ zymography. The IGF-1 induced the activation of canonical signaling pathways through the IGF-1R phosphorylation. Culture supernatants sho...
Experimental Eye Research, 2007
Panretinal photocoagulation (PRP) reduces the incidence of severe visual loss in proliferative di... more Panretinal photocoagulation (PRP) reduces the incidence of severe visual loss in proliferative diabetic retinopathy (PDR). The aim of the study was to determine the effect of PRP on the activity of matrix metalloproteinase-2 (MMP-2) and MMP-9, and also on the a 2 -Macroglobulin (a 2 M) proteolytic state in the vitreous of eyes with PDR. Vitreous samples were obtained from patients undergoing vitrectomy for the treatment of retinal diseases: 17 with PDR and eight with idiopathic macular hole (MH). Qualitative evaluation of the MMP-2 and MMP-9 activation status was performed by gelatin zymography and quantitative assay was carried out for vitreous total protein content and a 2 M. The proteolytic state of a 2 M was evaluated by Western blotting. Although all vitreous samples contained proMMP-2, increased proMMP-9 and active MMP-9 were detected in PDR samples without PRP. In addition, after PRP the proMMP-9 activity was significantly decreased, whereas the proMMP-2 activity was not affected. Enhanced total protein and a 2 M concentrations were observed in all vitreous samples from PDR patients with and without previous PRP compared with samples from patients with MH. However, a differential proteolytic state of a 2 M, expressed as 180/85e90 kDa ratio, was detected among PDR patients with and without PRP treatment. Whereas a low 180/85e90 kDa ratio of a 2 M in vitreous of PDR patients without PRP was observed, a high proportion of 180 kDa subunit was principally detected in PDR with PRP. These results demonstrate that PDR occurs with an enhanced activity of MMP-9 and activation of a 2 M by proteinases, which is reversed after PRP. In addition, we suggest that a 2 M plays a key role in the control and regulation of the ocular neovascularization involved in the pathogenesis of ischemic retinal diseases such as PDR.
Frontiers in microbiology, 2015
Quinolone resistance is usually due to mutations in the genes encoding bacterial topoisomerases. ... more Quinolone resistance is usually due to mutations in the genes encoding bacterial topoisomerases. However, different reports have shown that neither clinical quinolone resistant isolates nor in vitro obtained Stenotrophomonas maltophilia mutants present mutations in such genes. The mechanisms so far described consist on efflux pumps' overexpression. Our objective is to get information on novel mechanisms of S. maltophilia quinolone resistance. For this purpose, a transposon-insertion mutant library was obtained in S. maltophilia D457. One mutant presenting reduced susceptibility to nalidixic acid was selected. Inverse PCR showed that the inactivated gene encodes RNase G. Complementation of the mutant with wild-type RNase G allele restored the susceptibility to quinolones. Transcriptomic and real-time RT-PCR analyses showed that several genes encoding heat-shock response proteins were expressed at higher levels in the RNase defective mutant than in the wild-type strain. In agreement...
Frontiers in microbiology, 2015
Stenotrophomonas maltophilia is an environmental bacterium found in the soil, associated with pla... more Stenotrophomonas maltophilia is an environmental bacterium found in the soil, associated with plants and animals, and in aquatic environments. It is also an opportunistic pathogen now causing an increasing number of nosocomial infections. The treatment of S. maltophilia is quite difficult given its intrinsic resistance to a number of antibiotics, and because it is able to acquire new resistances via horizontal gene transfer and mutations. Certainly, strains resistant to quinolones, cotrimoxale and/or cephalosporins-antibiotics commonly used to treat S. maltophilia infections-have emerged. The increasing number of available S. maltophilia genomes has allowed the identification and annotation of a large number of antimicrobial resistance genes. Most encode inactivating enzymes and efflux pumps, but information on their role in intrinsic and acquired resistance is limited. Non-typical antibiotic resistance mechanisms that also form part of the intrinsic resistome have been identified v...
Psychophysiology, 2009
This study examines similarities and differences in fear potentiation between two protective refl... more This study examines similarities and differences in fear potentiation between two protective reflexes: cardiac defense and eyeblink startle. Women reporting intense fear of animals but low fear of blood or intense fear of blood but low fear of animals viewed pictures depicting blood or the feared animal for 6 s in 2 separate trials in counterbalanced order. An intense burst of white noise, able to elicit both a cardiac defense response and a reflexive startle blink, was presented 3.5 s after picture onset. Both cardiac and blink responses were potentiated when highly fearful individuals viewed fearful pictures. However, differences appeared concerning picture order. This pattern of results indicates communalities and differences among protective reflexes that are relevant for understanding the dynamics of emotional reflex modulation.
Gerokomos, 2007
ABSTRACT Introducción y objetivo: En el ámbito de las residencias de mayores es importante tener ... more ABSTRACT Introducción y objetivo: En el ámbito de las residencias de mayores es importante tener una visión integral del anciano y del envejecimiento activo para retardar la dependencia y potenciar la capacidad funcional y la autonomía. Partiendo de un abordaje interdisciplinar, nos planteamos elaborar un instrumento de valoración enfermera, basado en el modelo conceptual de Virginia Henderson y complementado con cuestionarios y escalas validadas, que nos permita detectar las necesidades del anciano, ponderar el riesgo de aparición de síndromes geriátricos y planificar los cuidados correspondientes. Método: Creación de grupo de trabajo, establecimiento de objetivos por consenso, revisión bibliográfica, desarrollo de criterios de elaboración, coordinación con el resto del equipo y validación del documento. Resultados: Obtenemos una hoja de valoración de enfermería para mayores institucionalizados en residencias, de 8 páginas, con ítems abiertos y cerrados, basada en el modelo de las 14 necesidades de Virginia Henderson y apoyada por nueve escalas de valoración, con su correspondiente guía de cumplimentación. Conclusiones: El tiempo empleado en la valoración enfermera geriátrica es una inversión necesaria para asegurar una asistencia adecuada y de calidad, ya que supone una herramienta de trabajo útil para enfermería y para el resto del equipo multidisciplinar del centro, al permitir individualizar los cuidados, cuantificar las incapacidades y proporcionar el nivel asistencial más adecuado a cada residente.
En la presente investigación se persigue la finalidad de valorar económicamente los recursos natu... more En la presente investigación se persigue la finalidad de valorar económicamente los recursos naturales del Parque Nacional Viñales de Cuba (PNV) en concordancia con el potencial turístico existente. La valoración se llevó a cabo a través de la aplicación combinada de varias técnicas, se analizan los factores externos e internos que muestran la situación predominante del producto ecoturístico y posteriormente se aplica el método de valoración contingente para la valoración económica de los bienes y servicios ambientales más representativos en las prácticas turísticas.
Journal of Wine Research, 2008
In an extremely competitive international market in which consumption is undergoing a period of s... more In an extremely competitive international market in which consumption is undergoing a period of stagnation, it is essential for businesses to develop and implement adequate control systems to help them deal with these circumstances. Cost management should provide relevant information to help grape-growers make better decisions and should even provide information for planning, control, and performance measurement. With this objective
Journal of Wine Research, 2010
Acceso de usuarios registrados. Acceso de usuarios registrados Usuario Contraseña. ...
Reumatología Clínica, 2012
Aquaculture Research, 2008
Journal of Molecular Spectroscopy, 2010
The diode laser absorption infrared spectrum of fluorobenzene has been recorded near 1230 cm À1 a... more The diode laser absorption infrared spectrum of fluorobenzene has been recorded near 1230 cm À1 after cooling the molecules in a supersonic pulsed jet. Spectral lines have been assigned to the m 7a fundamental band. Transitions of J between 32 and 49 have been recorded, that show characteristic line groupings in the P branch. Analysis of the spectrum gives the vibrational band origin and rotational and centrifugal distortion constants of the molecule in the m 7a = 1 state.
Canadian Journal of Chemistry, 2005
Page 1. The mechanisms of hydrolysis of alkyl N-alkylthioncarbamate esters at 100 °C1 Eduardo Hum... more Page 1. The mechanisms of hydrolysis of alkyl N-alkylthioncarbamate esters at 100 °C1 Eduardo Humeres, Maria de Nazaré M. Sanchez, Conceição ML Lobato, Nito A. Debacher, and Eduardo P. de Souza Abstract: The hydrolysis ...
Puerto Rico health sciences journal, 2013
The increasing demand for organ transplants exceeds the organ donation rate. Addressing this disc... more The increasing demand for organ transplants exceeds the organ donation rate. Addressing this discrepancy is challenging for organ procurement agencies and health professionals involved in the care of patients in dire need of organs. Research suggests that health-care professionals' knowledge of, attitudes toward, and behavior in terms of organ donation and transplantation are deciding variables in promoting organ donation. In Puerto Rico, there is a lack of information regarding medical student's knowledge of and/or attitudes toward organ donation, a lack that our study was designed to address. Two hundred thirty participants (98 first-year, 45 second-year, and 87 third-year medical students) completed a questionnaire consisting of 55 questions; 10 questions assessed knowledge and 20, attitudes about organ and tissue donation. The remaining questions inquired after demographic information, history of blood donation, and educational experience. In terms of their knowledge abo...
To compare the correlation between the departure areas (DA), negative or positive, in patients wh... more To compare the correlation between the departure areas (DA), negative or positive, in patients whose electrocardiogram showed left bundle branch block (LBBB) and association with left ventricular hipertrophy (LVH) and myocardial infarction (MI), to the electrocardiographic (ECG) and vectocardiographic (VCG) classic criteria. Methods -The study was carried out with 46 patients (27 males) with LBBB. These patients had hypertension (19.5%), coronary heart disease (34.7%) and 21 patients with no heart disease (45.8%). Results -The statistic analysis using the Cluster method divided the patients in two groups. Group I (22 patients) showed an average rate for the DA (-2 SD) of 1091 for QRS and of 640 for ST-T. For the DA (+2 SD), the average rate was 618 for QRS and 881 for ST-T; group II (24 patients) showed an averaged for the DA (-2 SD) of 1063 for QRS and of 225 for ST-T. For the DA (+2 SD), the averaged rate was 428 for QRS and 600 for ST-T. Conclusion -In general the current ECG/VCG findings, can not differentiate the presence of the association of LBBB to LVH and MI. The DA of ST-T, mainly negative was the most efficient to separate the two groups and help in the diferential diagnosis.
Fungi associated to postbloom fruit drop of Tahiti lime (Citrus latifolia Tan.) and evaluation of... more Fungi associated to postbloom fruit drop of Tahiti lime (Citrus latifolia Tan.) and evaluation of their chemical control Tahiti lime is an important crop with high economic potential in Monagas State, Venezuela. The incidence of diseases negatively affects crop yields, causing among other symptoms, postbloom fruit drop. In 2003 a trial was conducted in a commercial citrus orchard and four
Gastroenterología y Hepatología, 2008
2008;31(2):75-8 75
Rev Fed Arg …, 2005
La enfermedad coronaria es una de las principales causas de muerte en mujeres en los países desar... more La enfermedad coronaria es una de las principales causas de muerte en mujeres en los países desarro- llados a pesar de lo cual el diagnóstico no invasivo de esta patología en estas pacientes continúa siendo un tema controvertido. La información disponible para su valoración deriva de protocolos clínicos don- de la mayoría de la población son varones. En el presente
Neuropharmacology, 2015
Impact to the head or rapid head acceleration-deceleration can cause traumatic brain injury (TBI)... more Impact to the head or rapid head acceleration-deceleration can cause traumatic brain injury (TBI) with a characteristic pathology of traumatic axonal injury (TAI) and secondary damage in white matter tracts. Myelin and oligodendrocyte lineage cells have significant roles in the progression of white matter pathology after TBI and in the potential for plasticity and subsequent recovery. The myelination pattern of specific brain regions, such as frontal cortex, may also increase susceptibility to neurodegeneration and psychiatric symptoms after TBI. White matter pathology after TBI depends on the extent and distribution of axon damage, microhemorrhages and/or neuroinflammation. TAI occurs in a pattern of damaged axons dispersed among intact axons in white matter tracts. TAI accompanied by bleeding and/or inflammation produces focal regions of overt tissue destruction, resulting in loss of both axons and myelin. White matter regions with TAI may also exhibit demyelination of intact axons. Demyelinated axons that remain viable have the potential for remyelination and recovery of function. Indeed, animal models of TBI have demonstrated demyelination that is associated with evidence of remyelination, including oligodendrocyte progenitor cell proliferation, generation of new oligodendrocytes, and formation of thinner myelin. Changes in neuronal activity that accompany TBI may also involve myelin remodeling, which modifies conduction efficiency along intact myelinated fibers. Thus, effective remyelination and myelin remodeling may be neurobiological substrates of plasticity in neuronal circuits that require long-distance communication. This perspective integrates findings from multiple contexts to propose a model of myelin and oligodendrocyte lineage cell relevance in white matter injury after TBI.
Spectrochimica Acta Part B: Atomic Spectroscopy, 1997
A study is presented of the effects of the processes of redeposition of atomic vapor on the Arrhe... more A study is presented of the effects of the processes of redeposition of atomic vapor on the Arrhenius plots. For that purpose, a kinetic model that considers the redeposition of the initial atomic vapor, and the revaporization of the redeposited species, at a later time is proposed and tested for the electrothermal atomization of Cu. This model predicts Arrhenius plots which present negative deviations from the linear behavior expected for a single process of release and dissipation of the atomic vapor. The magnitude of the negative deviation increases as the readsorption rate and the temperature difference between the release and redeposition sites increase. This type of behavior is observed in the Arrhenius plots obtained when well used graphite tubes and ascorbic acid are employed for the atomization of Cu. However, when new pyrolytically coated graphite tubes, or tungstencoated tubes, are used, the Arrhenius plots show the expected linear behavior for the one-precursor model, with a first kinetic order of release. Additionally, when using Mo and Pd as modifiers, these plots shows two well defined slopes, which are characteristic of a two-precursor atomization mechanism. The experimental results indicate that the degree of vapor redeposition is determined not only by temperature gradients but also by the properties of the atomizer surface. © 1997 Elsevier Science B.V.
Investigative ophthalmology & visual science, 2015
In ischemic proliferative retinopathies, Müller glial cells (MGCs) acquire migratory abilities. H... more In ischemic proliferative retinopathies, Müller glial cells (MGCs) acquire migratory abilities. However, the mechanisms that regulate this migration remain poorly understood. In addition, proliferative disorders associated with enhanced activities of matrix metalloproteinases (MMPs) also involve insulin-like growth factor (IGF)-1 participation. Therefore, the main interest of this work was to investigate the IGF-1 effect on the extracellular proteolytic activity in MGCs. Cell culture supernatants and cell lysates of the human MGC line MIO-M1 stimulated with IGF-1 were analyzed for MMP-2 by zymographic and Western blot analysis. The MGCs' motility was evaluated by scratch wound assay. The MMP-2, β1-integrin, and focal adhesions were detected by confocal microscopy. The localization of active MMPs and actin cytoskeleton were evaluated by in situ zymography. The IGF-1 induced the activation of canonical signaling pathways through the IGF-1R phosphorylation. Culture supernatants sho...
Experimental Eye Research, 2007
Panretinal photocoagulation (PRP) reduces the incidence of severe visual loss in proliferative di... more Panretinal photocoagulation (PRP) reduces the incidence of severe visual loss in proliferative diabetic retinopathy (PDR). The aim of the study was to determine the effect of PRP on the activity of matrix metalloproteinase-2 (MMP-2) and MMP-9, and also on the a 2 -Macroglobulin (a 2 M) proteolytic state in the vitreous of eyes with PDR. Vitreous samples were obtained from patients undergoing vitrectomy for the treatment of retinal diseases: 17 with PDR and eight with idiopathic macular hole (MH). Qualitative evaluation of the MMP-2 and MMP-9 activation status was performed by gelatin zymography and quantitative assay was carried out for vitreous total protein content and a 2 M. The proteolytic state of a 2 M was evaluated by Western blotting. Although all vitreous samples contained proMMP-2, increased proMMP-9 and active MMP-9 were detected in PDR samples without PRP. In addition, after PRP the proMMP-9 activity was significantly decreased, whereas the proMMP-2 activity was not affected. Enhanced total protein and a 2 M concentrations were observed in all vitreous samples from PDR patients with and without previous PRP compared with samples from patients with MH. However, a differential proteolytic state of a 2 M, expressed as 180/85e90 kDa ratio, was detected among PDR patients with and without PRP treatment. Whereas a low 180/85e90 kDa ratio of a 2 M in vitreous of PDR patients without PRP was observed, a high proportion of 180 kDa subunit was principally detected in PDR with PRP. These results demonstrate that PDR occurs with an enhanced activity of MMP-9 and activation of a 2 M by proteinases, which is reversed after PRP. In addition, we suggest that a 2 M plays a key role in the control and regulation of the ocular neovascularization involved in the pathogenesis of ischemic retinal diseases such as PDR.
Frontiers in microbiology, 2015
Quinolone resistance is usually due to mutations in the genes encoding bacterial topoisomerases. ... more Quinolone resistance is usually due to mutations in the genes encoding bacterial topoisomerases. However, different reports have shown that neither clinical quinolone resistant isolates nor in vitro obtained Stenotrophomonas maltophilia mutants present mutations in such genes. The mechanisms so far described consist on efflux pumps' overexpression. Our objective is to get information on novel mechanisms of S. maltophilia quinolone resistance. For this purpose, a transposon-insertion mutant library was obtained in S. maltophilia D457. One mutant presenting reduced susceptibility to nalidixic acid was selected. Inverse PCR showed that the inactivated gene encodes RNase G. Complementation of the mutant with wild-type RNase G allele restored the susceptibility to quinolones. Transcriptomic and real-time RT-PCR analyses showed that several genes encoding heat-shock response proteins were expressed at higher levels in the RNase defective mutant than in the wild-type strain. In agreement...
Frontiers in microbiology, 2015
Stenotrophomonas maltophilia is an environmental bacterium found in the soil, associated with pla... more Stenotrophomonas maltophilia is an environmental bacterium found in the soil, associated with plants and animals, and in aquatic environments. It is also an opportunistic pathogen now causing an increasing number of nosocomial infections. The treatment of S. maltophilia is quite difficult given its intrinsic resistance to a number of antibiotics, and because it is able to acquire new resistances via horizontal gene transfer and mutations. Certainly, strains resistant to quinolones, cotrimoxale and/or cephalosporins-antibiotics commonly used to treat S. maltophilia infections-have emerged. The increasing number of available S. maltophilia genomes has allowed the identification and annotation of a large number of antimicrobial resistance genes. Most encode inactivating enzymes and efflux pumps, but information on their role in intrinsic and acquired resistance is limited. Non-typical antibiotic resistance mechanisms that also form part of the intrinsic resistome have been identified v...