Sildenafil citrate improves perinatal outcome in fetuses from pre-eclamptic rats.

OBJECTIVE: To evaluate perinatal outcome after sildenafil citrate (SC) administration at the onset of pregnancy in a rat pre-eclampsia model. DESIGN: In vivo animal experimental study. SETTING: Fundación IVI-Instituto Universitario IVI, Valencia, Spain. SAMPLE: Control and pre-eclampsia-induced pregnant Wistar rats exposed to chronic SC administration. METHODS: We evaluated the use of SC, which was tested as a potential therapeutic tool to maintain vasodilatation in complicated pregnancies. We have demonstrated previously that SC shows a hypotensive selective effect in normal rat pregnancies when compared with nonpregnant animals. MAIN OUTCOME MEASURES: Maternal blood pressure, weight and mortality during pre- and postnatal development, maternal blood cellularity and haemodynamic changes with maternal and fetal Doppler quantitative indices. RESULTS: SC restores normal values of blood pressure, cell count and proteinuria for maternal syndrome. In offspring, SC improves weight gain and increases survival rates without fetotoxic effects. According to the haemodynamic results, SC has a significant effect on the resistance index in the uterine artery in pre-eclamptic animals, as it restores normal values to correlate with an increase in fetal perfusion through the ductus venosus. CONCLUSIONS: These results suggest that SC administration during pregnancy may have a potential benefit for the treatment of hypertension during pregnancy by reversing the maternal effects of pre-eclampsia and by improving uteroplacental and fetal perfusion.

Haemodynamic effects of long-term administration of sildenafil in normotensive pregnant and non-pregnant rats.

OBJECTIVE: To determine the effects of chronic administration of sildenafil citrate on healthy pregnant rats. DESIGN: In vivo animal experimental study. SETTING: Fundación IVI-Instituto Universitario IVI, Valencia, Spain. SAMPLE: Pregnant and non-pregnant Wistar rats exposed to chronic administration of sildenafil. METHODS: Placental cross-barrier and feto-maternal relationship levels, maternal blood pressure, and haemodymamic effects on uterine arteries were evaluated. The effect of growth on weight and fetal tissues, and on perinatal outcome, was investigated. MAIN OUTCOME MEASURES: Maternal blood pressure, blood viscosity, vascular indices of uterine arteries and fetal ductus venosus, plasmatic levels of sildenafil, embryo/fetal and litter weights, perinatal/postnatal survival rates. RESULTS: Sildenafil citrate crossed the placenta. The maternal and fetal levels of sildenafil, and its metabolite desmethyl-sildenafil, demonstrated a positive linear correlation in treated pregnant animals versus controls; a selective maternal hypotensive effect without changes in uterine vascular resistance was noted on days E8 and E11 (embryonic day). The lower pulsatility index of the ductus venosus on day E18 suggests fetal overflow at the end of the pregnancy. Effects on offspring were placental and liver enlargement, and increased fetal weight gain in the second half of pregnancy (irrespective of liver enlargement) and at birth. Perinatal and postnatal survival rates in the sildenafil group remained unaltered. No haemodynamic effects were evident in non-pregnant animals. CONCLUSIONS: In normotensive rats, sildenafil appears to have a selective effect at the onset of pregnancy, implying increased fetal blood supply, and increased fetal weight, and placental and liver enlargement, but no increased perinatal mortality.

Ultrasound bioeffects in rats: quantification of cellular damage in the fetal liver after pulsed Doppler imaging.

OBJECTIVE: To determine whether pulsed Doppler examination of the ductus venosus in rat fetuses could damage exposed tissue. METHODS: On gestational day 18, the livers of a mean of approximately five fetuses per mother (n = 5.14, SD = 1.6), in a cohort of 35 pregnant female rats, were exposed individually to pulsed Doppler and these were considered the 'exposed group'. The remaining fetuses in each pregnant rat (n = 5.16, SD = 2.1) formed the 'control group'. We tested for 600, 300, 60, 20, 15, 10 and 3 s of exposure of the fetal ductus venosus and the damage was evaluated measuring a cell death index of apoptotic activity at 7 h post-exposure (n = 16). In addition, subgroups of mothers were sacrificed at 2, 4, 5, 7, 12 and 24 h post-exposure to determine when the damage appeared and disappeared and whether this depended on the exposure time. RESULTS: After exposure of 20 s or more, we observed significant damage, as assessed by caspase 3 activity (a marker of apoptotic activity related to tissue damage), in all cases; after 15 s of exposure, some samples presented damage (P = 0.4); there was no damage after 10 s or 3 s of exposure (P = 0.87 and P = 0.3, respectively). There was a positive linear correlation between apoptotic index and pulsed Doppler exposure time, (Pearson's coefficient = 0.324, P < 0.01). No liver still showed significant damage at 12 or 24 h post-exposure (P > 0.05 and P > 0.4). CONCLUSIONS: We observed reversible damage after pulsed Doppler imaging in an in-vivo fetal liver tissue rat model and found that longer exposure times produced more tissue damage. We established that 10 s was the maximum exposure time to ensure absence of damage to tissue in this model. It would appear sensible to recommend expert supervision of pulsed Doppler imaging and to have intervals between subsequent examinations.

[A systematic review and expert's analysis of risk factors of infections in adults due to carbapenem-resistant Pseudomonas aeruginosa or Acinetobacter baumannii in Spain]. / Revisión sistemática de la literatura y análisis de expertos sobre los factores de riesgo asociados a infecciones causadas por Pseudomonas aeruginosa o Acinetobacter baumannii resistentes a carbapenémicos en pacientes adultos en España.

OBJECTIVE: The aim of the study is to identify risk factors associated to infections caused by carbapenem-resistant Pseudomonas aeruginosa (CRPA) and carbapenem-resistant Acinetobacter baumannii (CRAB) in adult patients through a systematic literature review, classify them according to their importance and provide recommendations by experts in the Spanish context. METHODS: We developed a systematic literature review to identify risk factors associated to CRPA or CRAB infections and they were evaluated and discussed by a multidisciplinary panel of experts. RESULTS: There were included 29 studies for P. aeruginosa and 23 for A. baumannii out of 593 identified through systematic literature review. We identified 38 risk factors for P. aeruginosa and 36 for A. baumannii. After risk factor evaluation by the panel of experts, results for CRPA were: 11 important, 10 slightly important and 15 unimportant risk factors; and for CRAB were: 9 important, 5 slightly important and 19 unimportant risk factors. For both pathogens, previous use of antibiotics and hospitalization were important risk factors. CONCLUSIONS: We could identify the main risk factors associated to CRPA and CRAB through literature review. There is a need for developing additional studies with higher levels of evidence to identify sooner and better infected patients through associated risk factors.

Treatment with sildenafil prevents impairment of learning in rats born to pre-eclamptic mothers.

Pre-eclampsia is an important hypertensive pregnancy disorder and a main cause of maternal and fetal morbidity and mortality. Children born from mothers with pre-eclampsia may present cognitive deficits. The mechanisms leading to this cognitive impairment remain unclear and no treatments to improve it have been tested. Pre-eclampsia is associated with impaired regulation of the nitric oxide-3'-5'guanosine monophosphate cyclic (cGMP) pathway, which modulates some cognitive functions. We hypothesized that alterations in the NO-cGMP pathway would be involved in the mechanisms leading to cognitive impairment in rats born to pre-eclamptic mothers and that treatment with sildenafil, an inhibitor of the phosphodiesterase that degrades cGMP, could restore their cognitive function. To test these hypotheses, we used an animal model of pre-eclampsia in rats: pregnant rats treated with l-nitro-arginine methyl ester, an inhibitor of nitric oxide synthase. Using this model, we assessed: (1) whether rats born to pre-eclamptic mothers show reduced learning ability and/or altered motor activity or coordination when they are 2 months-old; (2) whether cognitive impairment is associated with reduced function of the glutamate-NO-cGMP pathway in brain in vivo; and (3) whether treatment of the mothers with sildenafil prevents this cognitive and motor alterations. The results reported show that the ability to learn a conditional discrimination task in a Y maze is reduced in rats born to pre-eclamptic mothers. This impairment was associated with reduced function of the glutamate-NO-cGMP pathway in brain in vivo, as assessed by microdialysis in freely moving rats. Treatment with sildenafil restores the function of this pathway and learning ability.

cGMP modulates stem cells differentiation to neurons in brain in vivo.

During brain development neural stem cells may differentiate to neurons or to other cell types. The aim of this work was to assess the role of cGMP (cyclic GMP) in the modulation of differentiation of neural stem cells to neurons or non-neuronal cells. cGMP in brain of fetuses was reduced to 46% of controls by treating pregnant rats with nitroarginine-methylester (L-NAME) and was restored by co-treatment with sildenafil.Reducing cGMP during brain development leads to reduced differentiation of stem cells to neurons and increased differentiation to non-neuronal cells. The number of neurons in the prefrontal cortex originated from stem cells proliferating on gestational day 14 was 715+/-14/mm(2) in control rats and was reduced to 440+/-29/mm(2) (61% of control) in rats treated with L-NAME. In rats exposed to L-NAME plus sildenafil, differentiation to neurons was completely normalized, reaching 683+/-11 neurons/mm(2). In rats exposed to sildenafil alone the number of cells labelled with bromodeoxyuridine (BrdU) and NeuN was 841+/-16/mm(2). In prefrontal cortex of control rats 48% of the neural stem cells proliferating in gestational day 14 differentiate to neurons, but only 24% in rats exposed to L-NAME. This was corrected by sildenafil, 40% of cells differentiate to neurons. Similar results were obtained for neurons proliferating during all developmental period. Treatment with L-NAME did not reduce the total number of cells labelled with BrdU, further supporting that L-NAME reduces selectively the differentiation of stem cells to neurons. Similar results were obtained in hippocampus. Treatment with L-NAME reduced the differentiation of neural stem cells to neurons, although the effect was milder than in prefrontal cortex. These results support that cGMP modulates the fate of neural stem cells in brain in vivo and suggest that high cGMP levels promote its differentiation to neurons while reduced cGMP levels promote differentiation to non-neuronal cells.