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Juan Carlos López

Publications and source records attributed to Juan Carlos López.

11 recordsLinked to original sources
PubMed2006

Severe hypertension in pregnancy: hydralazine or labetalol. A randomized clinical trial.

OBJECTIVE: The objective was to compare the safety and efficacy of intravenous labetalol and intravenous hydralazine for acutely lowering blood pressure in pregnancy. STUDY DESIGN: Two hundred women with severe hypertension in pregnancy were randomized to receive hydralazine (5 mg as a slow bolus dose given intravenously, and repeated every 20 min up to a maximum of five doses) or labetalol (20-mg intravenous bolus dose followed by 40 mg if not effective within 20 min, followed by 80 mg every 20 min up to a maximum dose of 300 mg). The primary end point was successful lowering of blood pressure and maternal hypotension. RESULTS: Women were similar with respect to characteristics at randomization. No significant differences were observed for maternal hypotension or persistent severe hypertension; only two patients in the hydralazine group presented with hypotension. Palpitations (p=0.01) and maternal tachycardia (p=0.05) occurred significantly more often in patients treated with hydralazine. The main neonatal outcomes were very similar per group; however, hypotension and bradycardia were significantly more frequent in the labetalol group. There were two neonatal deaths per antihypertensive drug group. CONCLUSIONS: This randomized clinical trial shows that labetalol and hydralazine fulfill the criteria required for an antihypertensive drug to treat severe hypertension in pregnancy.

Adrenergic Antagonists↗
PubMed2006

Spatial learning and goldfish telencephalon NMDA receptors.

Recent results have demonstrated that the mammalian hippocampus and the dorso-lateral telencephalon of ray-finned fishes share functional similarities in relation to spatial memory systems. In the present study, we investigated whether the physiological mechanisms of this hippocampus-dependent spatial memory system were also similar in mammals and ray-finned fishes, and therefore possibly conserved through evolution in vertebrates. In Experiment 1, we studied the effects of the intracranial administration of the noncompetitive NMDA receptor antagonist MK-801 during the acquisition of a spatial task. The results indicated dose-dependent drug-induced impairment of spatial memory. Experiment 2 evaluated if the MK-801 produced disruption of retrieval of a learned spatial response. Data showed that the administration of MK-801 did not impair the retrieval of the information previously stored. The last experiment analyzed the involvement of the telencephalic NMDA receptors in a spatial and in a cue task. Results showed a clear impairment in spatial learning but not in cue learning when NMDA receptors were blocked. As a whole, these results indicate that physiological mechanisms of this hippocampus-dependent system could be a general feature in vertebrate, and therefore phylogenetically conserved.

Animals↗
PubMed2006

Telencephalon and geometric space in goldfish.

Neuroanatomical evidence indicates that the lateral pallium (LP) of ray-finned fishes could be homologous to the hippocampus of mammals and birds. Recent studies have found that hippocampus of mammals and birds is critical for learning geometric properties of space. In this work, we studied the effects of lesions to the lateral pallium of goldfish on the encoding of geometric spatial information. Goldfish with telencephalic lesions were trained to search for a goal in a rectangular-shaped arena containing one different wall that served as the only distinctive environmental feature. Although fish with lateral pallium lesions learned the task even faster than sham and medial pallium (MP)-lesioned animals, subsequent probe trials showed that they were insensitive to geometric information. Sham and medial pallium-lesioned animals could use both geometric and feature information to locate the goal. By contrast, fish with lateral palium lesions relied exclusively on the feature information provided by the wall of a different colour. These results indicate that lesions to the lateral pallium of goldfish, like hippocampal lesions in mammals and birds, selectively impair the encoding of geometric spatial information of environmental space. Thus, the forebrain structures of teleost fish that are neuroanatomically equivalent to the mammalian and avian hippocampus also share a central role in supporting spatial cognition. Present results suggest that the presence of a hippocampal-dependent memory system implicated in the processing of geometric spatial information is an ancient feature of the vertebrate forebrain that has been conserved during the divergent evolution of different vertebrate groups.

Animals↗
PubMed2005

Different ways of encoding geometric information by goldfish (Carassius auratus).

On the basis of results of a probe trial in 2 different experiments, K. Cheng (2005) has proposed a common mechanism for orientation in fish trained in both a map-like or relational procedure and a directly cued procedure. However, K. Cheng's model is inconsistent with previous results of goldfish (Carassius auratus) trained in these 2 tasks. Given that K. Cheng's proposal assumes that fish choose the goal by using a matching strategy in which they try to match as many properties as possible, including geometric and featural properties, future research is necessary to clarify what properties of the environmental space are codified and used for navigation.

Animals↗
PubMed2004

Encoding of geometric and featural spatial information by goldfish (Carassius auratus).

Goldfish (Carassius auratus) were trained in different place-finding tasks as a means of analyzing their ability to encode the geometric and the featural properties of the environment. Results showed that goldfish could encode and use both geometric and featural information to navigate. Goldfish trained in a maplike, or relational, procedure encoded both types of information in a single representation. In contrast, fish trained in a directly cued procedure developed 2 independent and competing strategies. These results suggest that the geometric properties of the spatial arrangement and discrete landmarks are sensitive to encoding in a maplike or relational system, whereas different sources of spatial information are encoded in a single and flexible representation of the environment.

Animals↗
PubMed2004

Sleep smarts.

Explore the source record for details and available documents.

Humans↗
PubMed2003

Postnatal changes in the nitric oxide system of the rat cerebral cortex after hypoxia during delivery.

The impact of hypoxia in utero during delivery was correlated with the immunocytochemistry, expression and activity of the neuronal (nNOS) and inducible (iNOS) isoforms of the nitric oxide synthase enzyme as well as with the reactivity and expression of nitrotyrosine as a marker of protein nitration during early postnatal development of the cortex. The expression of nNOS in both normal and hypoxic animals increased during the first few postnatal days, reaching a peak at day P5, but a higher expression was consistently found in hypoxic brain. This expression decreased progressively from P7 to P20, but was more prominent in the hypoxic group. Immunoreactivity for iNOS was also higher in the cortex of the hypoxic rats and was more evident between days P0 and P5, decreasing dramatically between P10 and P20 in both groups of rats. Two nitrated proteins of 52 and 38 kDa, were also identified. Nitration of the 52-kDa protein was more intense in the hypoxic animals than in the controls, increasing from P0 to P7 and then decreasing progressively to P20. The 38-kDa nitrated protein was seen only from P10 to P20, and its expression was more intense in control than in the hypoxic group. These results suggest that the NO system may be involved in neuronal maturation and cortical plasticity over postnatal development. Overproduction of NO in the brain of hypoxic animals may constitute an effort to re-establish normal blood flow and may also trigger a cascade of free-radical reactions, leading to modifications in the cortical plasticity.

Animals↗
PubMed2003

Distribution of nitric oxide synthases and nitrotyrosine in the kidney of spontaneously hypertensive rats.

OBJECTIVES: To study the cellular distribution and the expression of the major isoforms of NO synthase (NOS) and of nitrotyrosine in the kidney in spontaneous hypertension. DESIGN AND METHODS: We have studied by immunohistochemistry the location of the endothelial (eNOS), neuronal (nNOS) and inducible (iNOS) isoforms and nitrotyrosine in kidney slices from normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) using specific antibodies. In order to quantify the expression of these proteins, we have analyzed dissected renal cortical and medullary sections by means of Western blot. RESULTS: Tubular cells were immunoreactive to nNOS and more numerous in the renal medulla of the SHR compared with that of the WKY, specifically in the outer medulla and the papillary region. Western blot also showed higher expression of nNOS in the renal medulla, but not the renal cortex of the SHR. In contrast, iNOS and eNOS distribution and expression were similar in the kidneys of WKY rats and SHR. Immunohistochemistry showed immunoreactive cells to nitrotyrosine in a variety of renal cells similarly distributed in SHR and WKY kidneys. Western analysis detected three proteins of 14.5, 23.7 and 39 kDa immunoreactive to nitrotyrosine, showing a higher expression in the renal cortex compared to the renal medulla. CONCLUSIONS: The expression of nNOS is higher in the renal medulla of the SHR, and the distribution of eNOS, iNOS and nitrotyrosine is similar in SHR and WKY rats. It is proposed that the higher expression of the neuronal isoform in the medullary tubular cells is a protective mechanism aimed to improve renal function in spontaneous hypertension.

Animals↗
PubMed2002

Geographic and ontogenic variability in the venom of the neotropical rattlesnake Crotalus durissus: pathophysiological and therapeutic implications.

A comparative study was performed on the venoms of adult specimens of the neotropical rattlesnake, Crotalus durissus, from Guatemala, Costa Rica, Venezuela and Brazil, together with the venom of newborn specimens of C. d. durissus from Costa Rica. Venoms from Brazil (C. d. terrificus) and from newborn specimens of C. d. durissus presented an electrophoretic pattern characterized by the predominance of bands with molecular mass of 36 and 15 kDa, whereas those of adult specimens of C. d. durissus from Guatemala and Costa Rica, and C. d. cumanensis from Venezuela, showed a conspicuous band of 62 kDa, and additional bands of 36, 29 and 15 kDa. Moreover, venoms from C. d. terrificus and C. d. cumanensis showed a prominent band of < 10 kDa that probably corresponds to crotamine, since a 'crotamine-like' activity was detected in these venoms upon intraperitoneal injection in mice. Venoms of C. d. terrificus, C. d cumanensis and newborn C. d. durissus induced higher lethal and myotoxic effects than those of adult C. d. durissus. In contrast, adult C. d. durissus and C. d. cumanensis venoms induced hemorrhage, whereas venoms of C. d. terrificus and newborn C. d. durissus lacked this effect. All venoms showed coagulant effect in plasma, the highest activity being observed in the venom of newborn C. d. durissus. An anti-crotalic antivenom produced by Instituto Butantan (Brazil), using C. d. terrificus venom as antigen, was effective in the neutralization of lethal, myotoxic and coagulant effects of all venoms studied, being ineffective in the neutralization of hemorrhagic activity of the venoms of C. d. cumanensis and C. d. durissus. On the other hand, a polyvalent antivenom produced by Instituto Clodomiro Picado (Costa Rica), using the venoms of C. d. durissus. Bothrops asper and Lachesis stenophrys as antigens, was able to neutralize lethal, myotoxic, coagulant and hemorrhagic effects of C. d. durissus venom, but was ineffective in the neutralization of lethality and myotoxicity of C. d. terrificus, C. d. cumanensis and newborn C. d. durissus venom. The high toxicity of South American and newborn C. d. durissus venoms is related to the presence of high concentrations of the neurotoxic phospholipase A2 complex 'crotoxin'. Accordingly, antivenom from Instituto Butantan has a much higher titer of anti-crotoxin antibodies than antivenom from Instituto Clodomiro Picado. Crotalus durissus represents an example of intraspecies variation in venom composition and pharmacology that has relevant pathophysiologic and therapeutic implications.

Animals↗
PubMedDate not supplied

A cohort study of the food effect on virological failure and treatment discontinuation in patients on HAART containing didanosine enteric-coated capsules (FOODDIe Study).

BACKGROUND: Didanosine enteric-coated capsules (ddI-EC) should be taken under fasting conditions. However, the effect of food on the absorption of ddI-EC may not reduce exposure to the drug. METHOD: We performed an observational study to assess the effect on virological failure of taking ddI-EC with food. To be included, patients had to have begun their first ddI-EC-containing HAART regimen between June 1, 2001 and June 1, 2003. Primary endpoints were virological failure or discontinuation of the ddI-EC-containing regimen. RESULTS: 668 patients were included (119 patients were naïve, 172 switched from a different regimen, and 377 were part of rescue therapy). 296 patients were taking ddI-EC with food. After 71 weeks of follow-up, 162 discontinued ddI-EC in the fasting group and 120 in the fed group. 46 patients had virological failure (19 without food vs. 27 in the group with food). Adherence to therapy >80% was 79.7%. We fitted a multivariate Cox proportional hazard model and found a significant interaction between ddI-EC intake and adherence. The multivariate model showed that when adherence to HAART was poor (<80% of prescribed pills) taking ddI-EC with food significantly increased the risk of virological failure (hazard ratio [HR] 8.32, 95% CI 1.67-41.65), but this disappeared when adherence was 80%-95% (HR 0.27, 95% CI 0.04-1.53) or >95% (HR 0.57, 95% CI 0.12-2.77). CONCLUSION: When adherence is good (>80% of the prescribed doses), ddI-EC can be administered with food without an increase in virological failure or HAART discontinuation.

Administration, Oral↗