Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology, 2014
The prefrontal cortex (PFC) is a brain region that is critically involved in cognitive function a... more The prefrontal cortex (PFC) is a brain region that is critically involved in cognitive function and inhibitory control of behavior, and adolescence represents an important period of continued PFC development that parallels the maturation of these functions. Evidence suggests that this period of continued development of the PFC may render it especially vulnerable to environmental insults that impact PFC function in adulthood. Experimentation with alcohol typically begins during adolescence when binge-like consumption of large quantities is common. In the present study, we investigated the effects of repeated cycles of adolescent intermittent ethanol (AIE) exposure (postnatal days 28-42) by vapor inhalation on different aspects of executive functioning in the adult rat. In an operant set-shifting task, AIE-exposed rats exhibited deficits in their ability to shift their response strategy when the rules of the task changed, indicating reduced behavioral flexibility. There were no differences in progressive ratio response for the reinforcer suggesting that AIE did not alter reinforcer motivation. Examination of performance on the elevated plus maze under conditions designed to minimize stress revealed that AIE exposure enhanced the number of entries into the open arms, which may reflect either reduced anxiety and/or disinhibition of exploratory-like behavior. In rats that trained to self-administer ethanol in an operant paradigm, AIE increased resistance to extinction of ethanol-seeking behavior. This resistance to extinction was reversed by positive allosteric modulation of mGluR5 during extinction training, an effect that is thought to reflect promotion of extinction learning mechanisms within the medial PFC. Consistent with this, CDPPB was also observed to reverse the deficits in behavioral flexibility. Finally, diffusion tensor imaging with multivariate analysis of 32 brain areas revealed that while there were no differences in the total brain volume, the volume of a subgroup of regions (hippocampus, thalamus, dorsal striatum, neocortex, and hypothalamus) were significantly different in AIE-exposed adults compared with litter-matched Control rats. Taken together, these findings demonstrate that binge-like exposure to alcohol during early to middle adolescence results in deficits in PFC-mediated behavioral control in adulthood.
Pneumonia is the most common nosocominal infection in intensive care units and mechanical ventila... more Pneumonia is the most common nosocominal infection in intensive care units and mechanical ventilation is a significant factor associated to its development. The objective of this study was to describe the impact of the open and closed tracheal suction systems on the incidence of ventilation-associated pneumonia. A search in the Pubmed database was performed to identify randomized controlled trials, published from 1990 to November 2008. Nine studies were included. Of the studies reviewed, seven did not disclose any significant advantages of using the closed system when compared to th e open, whereas two reported that use of the closed system increased colonization rates but not incidence of ventilation-associated pneumonia and one observed that use of the closed system did not increase colonization of the respiratory tract but reduced the spread of infection resulting in decreased sepsis rates. Only two studies found a reduction in the incidence of ventilation-associated pneumonia with use of the closed system, and one revealed a 3.5 times greater risk of developing this infection with the open system. Results suggest that the impact of the open and closed tracheal suction system is similar on development of ventilation-associated pneumonia, choice of the suction system should therefore be based on other parameters. While the closed system increases risk of colonization of the respiratory tract, but has the advantages of continuing mechanical ventilation and lessening hemodynamic impairment.
Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology, 2014
The prefrontal cortex (PFC) is a brain region that is critically involved in cognitive function a... more The prefrontal cortex (PFC) is a brain region that is critically involved in cognitive function and inhibitory control of behavior, and adolescence represents an important period of continued PFC development that parallels the maturation of these functions. Evidence suggests that this period of continued development of the PFC may render it especially vulnerable to environmental insults that impact PFC function in adulthood. Experimentation with alcohol typically begins during adolescence when binge-like consumption of large quantities is common. In the present study, we investigated the effects of repeated cycles of adolescent intermittent ethanol (AIE) exposure (postnatal days 28-42) by vapor inhalation on different aspects of executive functioning in the adult rat. In an operant set-shifting task, AIE-exposed rats exhibited deficits in their ability to shift their response strategy when the rules of the task changed, indicating reduced behavioral flexibility. There were no differences in progressive ratio response for the reinforcer suggesting that AIE did not alter reinforcer motivation. Examination of performance on the elevated plus maze under conditions designed to minimize stress revealed that AIE exposure enhanced the number of entries into the open arms, which may reflect either reduced anxiety and/or disinhibition of exploratory-like behavior. In rats that trained to self-administer ethanol in an operant paradigm, AIE increased resistance to extinction of ethanol-seeking behavior. This resistance to extinction was reversed by positive allosteric modulation of mGluR5 during extinction training, an effect that is thought to reflect promotion of extinction learning mechanisms within the medial PFC. Consistent with this, CDPPB was also observed to reverse the deficits in behavioral flexibility. Finally, diffusion tensor imaging with multivariate analysis of 32 brain areas revealed that while there were no differences in the total brain volume, the volume of a subgroup of regions (hippocampus, thalamus, dorsal striatum, neocortex, and hypothalamus) were significantly different in AIE-exposed adults compared with litter-matched Control rats. Taken together, these findings demonstrate that binge-like exposure to alcohol during early to middle adolescence results in deficits in PFC-mediated behavioral control in adulthood.
Pneumonia is the most common nosocominal infection in intensive care units and mechanical ventila... more Pneumonia is the most common nosocominal infection in intensive care units and mechanical ventilation is a significant factor associated to its development. The objective of this study was to describe the impact of the open and closed tracheal suction systems on the incidence of ventilation-associated pneumonia. A search in the Pubmed database was performed to identify randomized controlled trials, published from 1990 to November 2008. Nine studies were included. Of the studies reviewed, seven did not disclose any significant advantages of using the closed system when compared to th e open, whereas two reported that use of the closed system increased colonization rates but not incidence of ventilation-associated pneumonia and one observed that use of the closed system did not increase colonization of the respiratory tract but reduced the spread of infection resulting in decreased sepsis rates. Only two studies found a reduction in the incidence of ventilation-associated pneumonia with use of the closed system, and one revealed a 3.5 times greater risk of developing this infection with the open system. Results suggest that the impact of the open and closed tracheal suction system is similar on development of ventilation-associated pneumonia, choice of the suction system should therefore be based on other parameters. While the closed system increases risk of colonization of the respiratory tract, but has the advantages of continuing mechanical ventilation and lessening hemodynamic impairment.
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Papers by Marcelo Lopez