Santiago Lopez - Academia.edu (original) (raw)
Papers by Santiago Lopez
Phytomedicine, 1998
Twenty nine extracts belonging to eight species of the Argentine flora reported as antifungal in ... more Twenty nine extracts belonging to eight species of the Argentine flora reported as antifungal in folk medicine, were assayed for antifungal properties by using the agar dilution method, against a panel of yeasts, filamentous fungi as well as dermatophytes. Nine extracts belonging to six species, exhibited a broad spectrum of activity against Microsporum cants, Microsporum gypseum, Trichophyton mentagrophytes, Trichophyton rubrum and Epidermophyton floccosum, with MICs ranging from 25 to 900 μg/ml. A dichloromethanis extract of Polygonum ferrugineum was the most active extract with MICs from 25–50 μg/ml.To gain an insight into the mode of action of the active extracts they were evaluated for their inhibitory activities toward the fungal cell wall, using the whole cell Neurospora crassa hyphal growth inhibition agar diffusion assay. A hazy zone around the paper disk strongly suggested that the dichloromethane extracts from aerial parts of Polygonum punctatum, Polygonum ferrugineum and the bark of Luehea divaricata acted by inhibiting polymer synthesis or assembly of the cell wall. The clear zone of inhibition produced by the dichloromethane and methanol antifungal extracts of Xanthium spinosum could be ascribed to the fact that these extracts have another effect on fungal cells in addition to inhibition of cell walls.
American Journal of Pathology, 1999
The expression of adhesion molecules E-selectin, Pselectin , and intercellular adhesion molecule-... more The expression of adhesion molecules E-selectin, Pselectin , and intercellular adhesion molecule-1 (ICAM-1) was immunohistochemically investigated during the course of experimental murine listeriosis. Infection was monitored by microbiological count of blood , liver , and spleen. After an early generalized expression of P-selectin and ICAM-1 , a later regulation occurred specifically to areas of inflammation. Expression of E-selectin was faint and inconstantly detected in all of the studied organs. In the liver, typical lesions of murine listeriosis were related to the expression of ICAM-1 on sinusoidal endothelial cells and the biliary system and to the de novo expression of P-selectin in hepatic portal vessels. Inflammation in the spleen was related to the expression of ICAM-1 on red pulp sinusoidal cells , especially in the marginal sinus. High endothelial venules of inflamed lymph nodes also expressed P-selectin and ICAM-1. Lesions in the central nervous system appeared on day 3 after infection as a pyogranulomatous leptomeningitis associated with an intense expression of P-selectin and ICAM-1 in meningeal vessels , especially those in the hippocampal sulcus , suggesting a way through which inflammation initially reach the central nervous system during experimental murine listeriosis. Leptomeningitis was followed by the presence of ventriculitis , which was related to the upregulation of ICAM-1 on choroid plexus epithelial cells , periventricular vessels and ependymal cells. Up-regulation of P-selectin and ICAM-1 during experimental murine listeriosis could play an important role in the recruitment of leukocytes , especially to the liver , lymphoid organs , and central nervous system. Experimental murine listeriosis has long served as a model for studying host defense against infections caused by intracellular pathogens in general, 1 and listeriosis in particular. Systemic murine listeriosis is characterized by the rapid influx of leukocytes, especially neutrophils but also macrophages, into the site of initial bacterial replication, especially the liver and spleen. These cells have been shown to be essential for the early defense against the infection. 7,8 Leukocyte recruitment to inflammatory sites consists of a complex series of interactions mediated by cell adhesion molecules expressed on the surface of inflammatory and endothelial cells. The initial step in the adhesion cascade is the tethering and rolling of leukocytes along the endothelium, which is mediated by the interaction of members of the selectin family and their carbohydrate ligands. 9 -11 E-and P-selectin, expressed on the endothelial cell surface, have been shown to support the initial rolling phase of neutrophils and monocytes in vitro and in vivo. Firm adhesion to endothelium and subsequent emigration through the vessel wall is dependent on leukocyte 1 and 2 integrin activation and their interaction with members of the immunoglobulin-like superfamily on the endothelium, including intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). The use of the subcutaneous route of infection has been shown as a suitable model of systemic murine listeriosis, and can also reproduce central nervous system (CNS) lesions similar to those of listeria meningitis in humans and other species. The main feature of these lesions is the recruitment of inflammatory cells, especially macrophages and neutrophils, to the subarachnoid and ventricular space causing meningitis and choroiditis. 6
Microbial Pathogenesis, 1997
In this study, it is suggested that the Peyer&amp... more In this study, it is suggested that the Peyer's patches are the most important point of entry of Listeria monocytogenes in the host after subclinical infection by the oral route. Microbiological, histopathological and ultrastructural evidence of infection was obtained in mice inoculated with a sublethal dose of 10(9) cfu. No mortality was observed. L. monocytogenes was isolated from the mesenteric lymph nodes from 6 hours post infection (hpi) through day 7 p.i. and from the liver and spleen from 24 h p.i. until days 5 and 7 p.i. respectively. Lesions were mainly restricted to the dome area of Peyer's patches and consisted of a purulent to pyogranulomatous inflammatory reaction. Scarce and minor lesions were also observed in the mesenteric lymph nodes and liver. L. monocytogenes was detected by immunohistochemistry in the Peyer's patches from 12 h p. i. to day 6 p.i. Ultrastructural study of Peyer's patches showed that the majority of Listeria cells were free within the cytoplasm of neutrophils and macrophages, not surrounded by a phagosomal membrane, and some of them were dividing.
Infection and Immunity, 2000
Neutrophils are the main inflammatory cell present in lesions involving the central nervous syste... more Neutrophils are the main inflammatory cell present in lesions involving the central nervous system (CNS) during human and murine listeriosis. In this study, administration of the neutrophil-depleting monoclonal antibody RB6-8C5 during experimental murine listeriosis facilitated the multiplication of Listeria monocytogenes in the CNS. These data suggest that neutrophils play a key role in eliminating bacteria that gain access to the CNS compartment. In addition, we provide evidence that their migration into the CNS may be necessary for the subsequent recruitment of macrophages and activated lymphocytes.
IEEE Transactions on Nuclear Science, 2006
This paper describes an architecture model for data acquisition systems based on compact PCI plat... more This paper describes an architecture model for data acquisition systems based on compact PCI platforms. The aim is to increase real-time data processing capabilities in experimental environments such as nuclear fusion devices (e.g., ITER). The model has these features: 1) Real-time data acquisition: the system has been provided with real-time capabilities, developing specific data acquisition kernel modules under Linux and RTAI, using COMEDI project drivers; 2) Multiprocessor PCI eXtensions for Instrumentation (PXI) Architecture: the model makes possible to add one or more processing cards (in nonsystem slots) to each standard PXI chassis. Several real-time software modules have been developed to allow the communication between the PXI controller and the processing cards. This way the system performance is not restricted to the PXI controller's own performance. This model provides scalability to the system, adding or removing processing cards; 3) Real-time acquired data distribution: with this model it is possible to define how to distribute, in real-time, the data from all acquired signals in the system among the processing cards and the PXI controller; and 4) Dynamic Data Processing: a software platform has been developed to allow users to dynamically manage their own data processing algorithms in the system. This means that users can start, stop, modify, and replace their data processing algorithms without disrupting the data acquisition process or the rest of the data processing algorithms.
Pediatrics, 2000
Surfactant therapy has become an effective standard therapy for infants with respiratory distress... more Surfactant therapy has become an effective standard therapy for infants with respiratory distress syndrome (RDS). The first dose may be given either as prophylaxis immediately after delivery, or as rescue after an infant has developed RDS. Second and subsequent doses are currently recommended by the manufacturers to be administered at minimal levels of respiratory support. This study compared the relative efficacy of administering second and subsequent doses of Infasurf surfactant at a low threshold (FIO(2) >30%, still requiring endotracheal intubation) versus a high threshold (FIO(2) >40%, mean airway pressure >7 cm H(2)O) of respiratory support. A total of 2484 neonates received a first dose of surfactant; 1267 reached conventional retreatment criteria and were randomized to be retreated according to low- or high-threshold criteria. They were then retreated at a minimum of 6-hour intervals each time they reached their assigned threshold until receiving a maximum of 4 total doses. Subjects were stratified by whether they received their first dose by prophylaxis or rescue and by whether their lung disease was considered complicated (evidence of perinatal compromise or sepsis) or uncomplicated. Among the patients randomized, 33% of prophylaxis and 23% of rescue subjects met criteria for the complicated stratum. Although infants allocated to the high-threshold strategy were receiving slightly more oxygen at 72 hours, there was no difference in the number receiving mechanical ventilation at 72 hours or in the secondary respiratory outcomes (requirement for supplemental oxygen or mechanical ventilation at 28 days, supplemental oxygen at 36 weeks' postconceptional age, inspired oxygen concentration >60% at any time). However, there was a significantly higher mortality for infants with complicated RDS who had received retreatment according to the high-threshold strategy. We conclude that equal efficacy can be realized by delaying surfactant retreatment of infants with uncomplicated RDS until they have reached a higher level of respiratory support than is the current standard. We speculate that this would result in a substantial cost-saving from less utilization of drug. Conversely, we believe that infants with complicated RDS should continue to be treated by the low-threshold retreatment strategy, which is currently recommended by the manufacturers of the commercially available surfactants.
Phytomedicine, 1998
Twenty nine extracts belonging to eight species of the Argentine flora reported as antifungal in ... more Twenty nine extracts belonging to eight species of the Argentine flora reported as antifungal in folk medicine, were assayed for antifungal properties by using the agar dilution method, against a panel of yeasts, filamentous fungi as well as dermatophytes. Nine extracts belonging to six species, exhibited a broad spectrum of activity against Microsporum cants, Microsporum gypseum, Trichophyton mentagrophytes, Trichophyton rubrum and Epidermophyton floccosum, with MICs ranging from 25 to 900 μg/ml. A dichloromethanis extract of Polygonum ferrugineum was the most active extract with MICs from 25–50 μg/ml.To gain an insight into the mode of action of the active extracts they were evaluated for their inhibitory activities toward the fungal cell wall, using the whole cell Neurospora crassa hyphal growth inhibition agar diffusion assay. A hazy zone around the paper disk strongly suggested that the dichloromethane extracts from aerial parts of Polygonum punctatum, Polygonum ferrugineum and the bark of Luehea divaricata acted by inhibiting polymer synthesis or assembly of the cell wall. The clear zone of inhibition produced by the dichloromethane and methanol antifungal extracts of Xanthium spinosum could be ascribed to the fact that these extracts have another effect on fungal cells in addition to inhibition of cell walls.
American Journal of Pathology, 1999
The expression of adhesion molecules E-selectin, Pselectin , and intercellular adhesion molecule-... more The expression of adhesion molecules E-selectin, Pselectin , and intercellular adhesion molecule-1 (ICAM-1) was immunohistochemically investigated during the course of experimental murine listeriosis. Infection was monitored by microbiological count of blood , liver , and spleen. After an early generalized expression of P-selectin and ICAM-1 , a later regulation occurred specifically to areas of inflammation. Expression of E-selectin was faint and inconstantly detected in all of the studied organs. In the liver, typical lesions of murine listeriosis were related to the expression of ICAM-1 on sinusoidal endothelial cells and the biliary system and to the de novo expression of P-selectin in hepatic portal vessels. Inflammation in the spleen was related to the expression of ICAM-1 on red pulp sinusoidal cells , especially in the marginal sinus. High endothelial venules of inflamed lymph nodes also expressed P-selectin and ICAM-1. Lesions in the central nervous system appeared on day 3 after infection as a pyogranulomatous leptomeningitis associated with an intense expression of P-selectin and ICAM-1 in meningeal vessels , especially those in the hippocampal sulcus , suggesting a way through which inflammation initially reach the central nervous system during experimental murine listeriosis. Leptomeningitis was followed by the presence of ventriculitis , which was related to the upregulation of ICAM-1 on choroid plexus epithelial cells , periventricular vessels and ependymal cells. Up-regulation of P-selectin and ICAM-1 during experimental murine listeriosis could play an important role in the recruitment of leukocytes , especially to the liver , lymphoid organs , and central nervous system. Experimental murine listeriosis has long served as a model for studying host defense against infections caused by intracellular pathogens in general, 1 and listeriosis in particular. Systemic murine listeriosis is characterized by the rapid influx of leukocytes, especially neutrophils but also macrophages, into the site of initial bacterial replication, especially the liver and spleen. These cells have been shown to be essential for the early defense against the infection. 7,8 Leukocyte recruitment to inflammatory sites consists of a complex series of interactions mediated by cell adhesion molecules expressed on the surface of inflammatory and endothelial cells. The initial step in the adhesion cascade is the tethering and rolling of leukocytes along the endothelium, which is mediated by the interaction of members of the selectin family and their carbohydrate ligands. 9 -11 E-and P-selectin, expressed on the endothelial cell surface, have been shown to support the initial rolling phase of neutrophils and monocytes in vitro and in vivo. Firm adhesion to endothelium and subsequent emigration through the vessel wall is dependent on leukocyte 1 and 2 integrin activation and their interaction with members of the immunoglobulin-like superfamily on the endothelium, including intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). The use of the subcutaneous route of infection has been shown as a suitable model of systemic murine listeriosis, and can also reproduce central nervous system (CNS) lesions similar to those of listeria meningitis in humans and other species. The main feature of these lesions is the recruitment of inflammatory cells, especially macrophages and neutrophils, to the subarachnoid and ventricular space causing meningitis and choroiditis. 6
Microbial Pathogenesis, 1997
In this study, it is suggested that the Peyer&amp... more In this study, it is suggested that the Peyer's patches are the most important point of entry of Listeria monocytogenes in the host after subclinical infection by the oral route. Microbiological, histopathological and ultrastructural evidence of infection was obtained in mice inoculated with a sublethal dose of 10(9) cfu. No mortality was observed. L. monocytogenes was isolated from the mesenteric lymph nodes from 6 hours post infection (hpi) through day 7 p.i. and from the liver and spleen from 24 h p.i. until days 5 and 7 p.i. respectively. Lesions were mainly restricted to the dome area of Peyer's patches and consisted of a purulent to pyogranulomatous inflammatory reaction. Scarce and minor lesions were also observed in the mesenteric lymph nodes and liver. L. monocytogenes was detected by immunohistochemistry in the Peyer's patches from 12 h p. i. to day 6 p.i. Ultrastructural study of Peyer's patches showed that the majority of Listeria cells were free within the cytoplasm of neutrophils and macrophages, not surrounded by a phagosomal membrane, and some of them were dividing.
Infection and Immunity, 2000
Neutrophils are the main inflammatory cell present in lesions involving the central nervous syste... more Neutrophils are the main inflammatory cell present in lesions involving the central nervous system (CNS) during human and murine listeriosis. In this study, administration of the neutrophil-depleting monoclonal antibody RB6-8C5 during experimental murine listeriosis facilitated the multiplication of Listeria monocytogenes in the CNS. These data suggest that neutrophils play a key role in eliminating bacteria that gain access to the CNS compartment. In addition, we provide evidence that their migration into the CNS may be necessary for the subsequent recruitment of macrophages and activated lymphocytes.
IEEE Transactions on Nuclear Science, 2006
This paper describes an architecture model for data acquisition systems based on compact PCI plat... more This paper describes an architecture model for data acquisition systems based on compact PCI platforms. The aim is to increase real-time data processing capabilities in experimental environments such as nuclear fusion devices (e.g., ITER). The model has these features: 1) Real-time data acquisition: the system has been provided with real-time capabilities, developing specific data acquisition kernel modules under Linux and RTAI, using COMEDI project drivers; 2) Multiprocessor PCI eXtensions for Instrumentation (PXI) Architecture: the model makes possible to add one or more processing cards (in nonsystem slots) to each standard PXI chassis. Several real-time software modules have been developed to allow the communication between the PXI controller and the processing cards. This way the system performance is not restricted to the PXI controller's own performance. This model provides scalability to the system, adding or removing processing cards; 3) Real-time acquired data distribution: with this model it is possible to define how to distribute, in real-time, the data from all acquired signals in the system among the processing cards and the PXI controller; and 4) Dynamic Data Processing: a software platform has been developed to allow users to dynamically manage their own data processing algorithms in the system. This means that users can start, stop, modify, and replace their data processing algorithms without disrupting the data acquisition process or the rest of the data processing algorithms.
Pediatrics, 2000
Surfactant therapy has become an effective standard therapy for infants with respiratory distress... more Surfactant therapy has become an effective standard therapy for infants with respiratory distress syndrome (RDS). The first dose may be given either as prophylaxis immediately after delivery, or as rescue after an infant has developed RDS. Second and subsequent doses are currently recommended by the manufacturers to be administered at minimal levels of respiratory support. This study compared the relative efficacy of administering second and subsequent doses of Infasurf surfactant at a low threshold (FIO(2) >30%, still requiring endotracheal intubation) versus a high threshold (FIO(2) >40%, mean airway pressure >7 cm H(2)O) of respiratory support. A total of 2484 neonates received a first dose of surfactant; 1267 reached conventional retreatment criteria and were randomized to be retreated according to low- or high-threshold criteria. They were then retreated at a minimum of 6-hour intervals each time they reached their assigned threshold until receiving a maximum of 4 total doses. Subjects were stratified by whether they received their first dose by prophylaxis or rescue and by whether their lung disease was considered complicated (evidence of perinatal compromise or sepsis) or uncomplicated. Among the patients randomized, 33% of prophylaxis and 23% of rescue subjects met criteria for the complicated stratum. Although infants allocated to the high-threshold strategy were receiving slightly more oxygen at 72 hours, there was no difference in the number receiving mechanical ventilation at 72 hours or in the secondary respiratory outcomes (requirement for supplemental oxygen or mechanical ventilation at 28 days, supplemental oxygen at 36 weeks' postconceptional age, inspired oxygen concentration >60% at any time). However, there was a significantly higher mortality for infants with complicated RDS who had received retreatment according to the high-threshold strategy. We conclude that equal efficacy can be realized by delaying surfactant retreatment of infants with uncomplicated RDS until they have reached a higher level of respiratory support than is the current standard. We speculate that this would result in a substantial cost-saving from less utilization of drug. Conversely, we believe that infants with complicated RDS should continue to be treated by the low-threshold retreatment strategy, which is currently recommended by the manufacturers of the commercially available surfactants.