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L Paz

Publications and source records attributed to L Paz.

18 recordsLinked to original sources
PubMed2001

Behavioral effects of agents active at the gamma-aminobutyric acid receptor complex in the staircase paradigm.

This study examined the behavioral effects of agents active at the gamma-aminobutyric acid (GABA(A)) receptor complex in the mouse staircase paradigm. The neuroactivesteroids dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEA-S) were compared with the benzodiazepine agonist clonazepam, the non-benzodiazepine hypnotic compound zopiclone, and the antiepileptic agent gabapentin. Clonazepam, zopiclone and gabapentin reduced rearing activity at doses that did not affect climbing. The rearing-suppression effect of clonazepam and zopiclone, but not of gabapentin, was blocked by the benzodiazepine antagonist flumazenil, suggesting that the added effect of gabapentin is not mediated by the benzodiazepine receptor on the GABA complex. DHEA suppressed rearing behavior at doses that did not reduce climbing, but analysis with the Bonferroni post hoc test yielded no statistically significant difference. This inhibitory effect was attenuated by flumazenil. By contrast, DHEA-S suppressed, in a dose-dependent manner, both rearing and climbing behavior to the same extent. The findings support the potential value of the mouse staircase paradigm for demonstrating behaviorally relevant anxiolysis of test compounds shown to interact in vitro with the GABA(A) receptor complex.

Acetates↗
PubMed2001

Mice performance on the staircase test following acute ethanol administration.

This study examined the effect of acute ethanol administration as compared to diazepam on the number of rearing events and the number of steps ascended in the mouse staircase test, an animal model sensitive to benzodiazepines. Acute ethanol administration, similar to acute diazepam administration, reduces rearing (at doses that do not reduce climbing) in the staircase test. This effect of acute ethanol administration is insensitive to the benzodiazepine antagonist flumazenil and is not consistently counteracted by the partial inverse agonist Ro15-4513. It seems that the mouse staircase test is an efficient paradigm for studying agents active at the gamma-aminobutyric acid (GABA(A)) receptor complex, including ethanol.

Animals↗
PubMed1999

Mouse strains differ in their sensitivity to alprazolam effect in the staircase test.

The behavioral responses of five mouse strains (inbred: C57 and BALB/c; outbred: Swiss, ICR and HS/Ibg) to alprazolam was examined in the staircase test, an animal model sensitive to benzodiazepines (BZs). Alprazolam administration resulted in a dose-dependent suppression of rearing behavior, but to a different extent among the strains. By contrast, the number of stairs ascended was not suppressed by alprazolam at doses of 0.25 and 0.5 mg/kg, except in the C57 mice. The addition of flumazenil antagonized the alprazolam effect on rearing and climbing in all strains. There was a consistency within strains in sensitivity to alprazolam, with some strains being highly sensitive (C57 and HS) or less sensitive (Swiss, ICR and BALB/c) with regard to both rearing and climbing behaviors. Serum alprazolam levels did not differ significantly among the strains. This strain-dependent pattern of response to alprazolam seems to indicate a genetic component, rather than pharmacokinetic, in the behavior sensitivity to the BZ, with a spectrum of degree of responsivity among strains.

Alprazolam↗
PubMed1998

Generalized background qEEG abnormalities in localized symptomatic epilepsy.

Spectral features of EEG background activity were studied in patients with localized symptomatic epilepsy (LSE), with origin in the frontal or temporal lobes. Z-values of high resolution spectra and measures of the parametric (xi alpha) model of the EEG were obtained for all 10/20 System leads and were compared with those obtained in a control group. Comparisons were performed between syndromic variants of LSE and between subgroups of patients with or without paroxysmal activity in their digital EEGs (dEEG). Marked reduction of the energy in the alpha range and a mild increase in the theta range were found in the patients, unrelated to the syndromic variant of the epilepsy. These deviations from normality were widespread on the scalp and were not related to antiepileptic medication. Non-parametric testing showed a positive correlation between the magnitude of the quantitative EEG abnormalities and the amount of paroxysmal activity in the dEEG. Slowing of the mean frequency of alpha components of the spectra, an actual decrease of power in the alpha range and an increase in the theta range explained the results. The most striking finding of this paper is that focal epileptogenesis may have a generalized impact in the frequency composition of EEG.

Adolescent↗
PubMed1998

Regulation of cell cyclic AMP in medullary thick ascending limb of Henle in a rat model of chronic renal failure.

Chronic renal failure (CRF) is accompanied by adaptive changes in electrolyte reabsorption in the thick ascending limb of Henle of surviving nephrons. To study the cellular mechanism of this adaptation, we measured intracellular cAMP in micro-dissected medullary thick ascending limb (mTAL) segments in rats with CRF. mTAL exhibited in CRF an increase of basal cAMP from 25.6 +/- 10.0 in controls to 65.8 +/- 11.3 fmol mm-1 tubule in CRF (P < 0.05). Vasopressin and calcitonin stimulated mTAL adenylate-cyclase in a dose-dependent manner in controls but failed to stimulate in CRF. Likewise, maximal stimulation with 10(-3) M 3-isobutyl-1-methylxanthine (IBMX) plus 10(-5) M forskolin increased cAMP in controls to 63.0 +/- 16.0 but not in CRF, where maximal stimulated values remained at 63.1 +/- 18.8 fmol mm-1 tubule (P NS). Alpha2-adrenoreceptor activation with clonidine at concentrations ranging from 10(-8) to 10(-6) M diminished cAMP production by 37% in CRF (P < 0.05), whereas no differences were found in controls. Thus, the basal intracellular cAMP is increased in rat mTAL in CRF. The finding that neither forskolin nor vasopressin were able to further augment intracellular cAMP would suggest that stimulatory pathways of the adenylate-cyclase system are activated in the basal state. However, mTAL cells in CRF seem to retain the response of normal epithelium to inhibitory pathways such as the one mediated by alpha2-adrenoreceptors.

1-Methyl-3-isobutylxanthine↗
PubMed1998

[Paraneoplastic neuropathy with positive anti-Hu].

The case of a 72-year-old woman presenting sensory neuropathy and anti-Hu antibodies is reported. She was admitted in November 1995 with a one year history of sensory neuropathy. Her first symptoms were painful numbness and dysesthesias in both feet. She experienced progression of the sensory symptoms affecting upper limbs, and clumsiness of gait. One month before admission she complained of diminished strength in both hands. The neurologic examination showed anicocoric fixed pupils, with no reaction to light; convergence miosis was evident in the right eye (Argyll-Robertson pupil). In the lower limbs she had very mild distal weakness, and tendon reflexes were universally abolished. Pin and touch sensation, position sense and pallesthesia were absent in all four limbs. Romberg test was elicited, and a tabetic gait was patent. Pseudoathetotic movements were observed in hands and feet. An ulcer was present in the fifth finger of the right foot. Routine blood biochemistry and hematology showed a ESR of 105 and an increased IgG in the immune-electrophoretic run. Neurophysiologic evaluation disclosed a mild demyelinating neuropathy. Positive anti-Hu antibodies were found in the serum (Western blot - Athena Diagnostics); CSF was normal but not tested for anit-Hu. An abdominal CT scan disclosed multiple hypodense nodules in liver, right adrenal gland and peritoneum. A chest CT scan showed a hyperdense mass in the lower right pulmonary lobe and enlarged retrocava-pretracheal lymph nodes. A biopsy of the peritoneal nodule was performed, showing a metastatic small cell carcinoma. The patient died eight days after discharge. Although multiple organs were affected, she was independent until death, showing an indolent clinical course.

Aged↗
PubMed1997

Effect of the pregnane-related GABA-active steroid alphaxalone on mice performance in the staircase test.

We evaluated the modulatory effect of the GABA-active neurosteroid alphaxalone on the staircase test behavior of mice. Results were compared with the benzodiazepine alprazolam, the GABA(A) agonist muscimol and the peripheral steroids corticosterone and progesterone. Alphaxalone and alprazolam reduced rearing activity in a dose-dependent manner, at doses that did not suppress climbing. The rearing-suppression effect of alprazolam, but not of alphaxalone, was blocked by the benzodiazepine antagonist flumazenil. No such dissociation between the effect on rearing and climbing was obtained with muscimol, and both activities were suppressed, in a flumazenil-insensitive pattern, at high doses. Corticosterone and progesterone did not affect the behavior of the mice. The lack of sensitivity of both phenobarbital and alphaxalone to flumazenil indicates that neither agents act via the benzodiazepine recognition site at the GABA(A) receptor complex.

Alprazolam↗
PubMed1996

[Hypertriglyceridemia following treatment with interferon alpha in essential thrombocythemia].

A case of essential thrombocytemia treated with alpha interferon is reported, with hematological remission, but as a side effect hypertriglyceridemia is relevant. It was normalized when alpha interferon was stopped. This is the first case of essential thrombocythemia in Venezuela treated with biological modifiers, with hematological remission, but with hypertriglyceridemia as side effect.

Adult↗
PubMed1994

Identification of bloodmeal sources of Lutzomyia spp. in Peru.

Bloodmeal sources of Lutzomyia spp. were determined, using the bloodmeal analysis precipitin test, in Chaute, Lima, Peru, an area endemic for cutaneous leishmaniasis (uta). From April 1990 to May 1991, sandflies were sampled in and around the village houses, with CDC light traps and a Shannon trap with protected human bait, respectively. Overall, 1424 sandflies were collected engorged. In indoor collections, human blood (N = 275) was the most frequent bloodmeal found, followed by cow (171) and cat (152). The most frequent bloodmeals of the flies caught in the Shannon trap collections were from cow (31), man (23) and cat (23). Of the two predominant sandfly species in the area, Lutzomyia peruensis was more anthropophilic than Lu. verrucarum (chi 2 = 14.13, P < 0.001). The sandflies from Chaute appear to be opportunistic feeders; 16 different hosts were identified. There was evidence of bloodmeals from more than one host in each of 151 sandflies, including bloodmeals containing blood from an animal only present within the houses mixed with blood from animals only present in the corrals near the house. Some sandflies must therefore have flown from the corrals to the houses (or vice versa) to take the last bloodmeals before their capture.

Animals↗
PubMed1993

[Influence of iron status on attention and intellectual performance of a population of Spanish adolescents].

Dietetic, hematologic and biochemical data were used to asses the iron status of a group of 64 adolescents (37 males and 27 females), aged 15 to 18 (mean age 15.94 +/- 0.76 years), who study in a High School in the comunidad Autónoma de Madrid. All were asked to keep a dietary record during 5 days, one of which had to be a sunday. Iron intake was estimated using the Food Composition Tables of the Instituto de Nutrición (1990). The hematologic survey determined hemoglobin hematocrit mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), serum iron and serum ferritin. These data were correlated with the scores obtained in the attention and school capability test (AT), that gave information about the verbal (V), reasoning (R) and calculus (C) capabilities. There is a positive correlation between MCV (r = 0.2705), MCH (r = 0.3370) ferritin (r = 0.3383) and attention. MCV (r = 0.2995), MCH (r = 0.3998), MCHC (r = 0.3134) and ferritin (r = 0.3970) were also correlated with the speed capability shown on the attention test and the hemoglobin level was correlated with the calculus capability (r = 0.2905). The students who obtained higher scores in the school capability test had also better blood parameter values. This was statistically significant for serum ferritin in males students and for hemoglobin and MCHC in female students. 19.6% of the adolescents had ferritin levels lower than 12 ng/ml. Their intelligence test scores were lower to those who had serum ferritin > or = 12 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Lutzomyia verrucarum can transmit Leishmania peruviana, the aetiological agent of Andean cutaneous leishmaniasis.

In much of the endemic area for cutaneous leishmaniasis (uta) in the Peruvian Andes, the only 2 anthropophilic sandfly species present are Lutzomyia peruensis and Lu. verrucarum. On the basis of a single confirmed isolation of Leishmania peruviana (the aetiological agent of uta) from a wild Lu. peruensis, and apparent associations between sandfly abundance and the incidence of uta, it is generally believed that Lu. peruensis is the most important vector. In this paper, a potential role for Lu. verrucarum in the transmission of uta is indicated by laboratory experiments which show that this species is vectorially competent for L. peruviana. Individual or pooled colonized sandflies were permitted to take a second blood meal on 22 susceptible golden hamsters at varying intervals after feeding on hamsters previously infected with L. peruviana. Transmission was achieved by a single infected sandfly (of a total of 59) following a 15 d incubation period. Transmission was recognized by the characteristic clinical response (footpad swelling) associated with hamsters which have been inoculated with L. peruviana, and by the presence of parasites in aspirates made from the swollen footpad, detected by the polymerase chain reaction (PCR) and by parasite isolations in biphasic blood-agar culture medium. The identity of the parasite isolates was also confirmed by PCR (specific for parasites in the L. braziliensis complex). This is the first reported experimental transmission of L. peruviana by any sandfly species.

Animals↗
PubMedDate not supplied

Natural Leishmania infection of Lutzomyia spp. in Peru.

Natural infection of Lutzomyia spp. with Leishmania was studied with the aid of the polymerase chain reaction (PCR) in Chaute, Lima, Perú, a locality endemic for Andean cutaneous leishmaniasis (uta). The PCR, with primers specific for the L. braziliensis complex, was applied to sandfly pools. Sandflies were sampled from April 1990 to May 1991 with CDC light traps in homes, and from near homes with a Shannon trap using protected human bait. Lu. verrucarum (4 pools) and Lu. peruenis (2 pools) from the anthropophilic collections, and Lu. verrucarum (2 pools) from indoors were found to be infected with Leishmania. The majority of infected sandflies were recorded mainly in April 1991 (4 pools), coinciding with the highest sandfly densities and the maximum number of new cases of uta (7). Non-infected sandflies were found from May to October 1990 and January to March 1991. Thus, these 2 sandfly species play a role in the spread of leishmaniasis among humans and other animals in Chaute.

Animals↗
PubMedDate not supplied

Natural infections of Leishmania peruviana in animals in the Peruvian Andes.

Evidence that domestic dogs may act as reservoir hosts for cutaneous leishmaniasis in the Peruvian Andes is provided by the isolation, for the first time, from naturally infected dogs of parasites identified (by isoenzymes) as Leishmania peruviana. Leishmania parasites were isolated from nasal aspirates or biopsies from 5 (1.8%) of 279 asymptomatic dogs samples in endemic villages of the Peruvian Andes. In addition, Leishmania (Viannia) infections were identified in 15 (5.4%) of 276 nasal samples by the polymerase chain reaction (PCR) using subgenus-specific primers. Further circumstantial evidence for a reservoir role for dogs comes from the finding of a relatively high dog blood index among the sandfly vectors collected inside houses (29% for Lutzomyia peruensis and 17% for Lu. verrucarum). Possible wild mammal reservoir hosts for Andean cutaneous leishmaniasis were also detected in endemic villages. At least 8 species were identified among the 1266 small mammals trapped. Leishmania parasites were isolated from blood or skin biopsies taken from 2 (2.6%) of 78 Didelphis albiventris and 6 (1.2%) of 511 Phyllotis andinum. Three isolates were identified by isoenzymes as L. peruviana, and the other 5 were identified by PCR as Leishmania (Viannia) species. Leishmania (Viannia) infections were also identified by PCR directly on skin biopsies taken from 2 (2.8%) of 72 D. albiventris, 1 (0.2%) of 499 P. andinum, and 4 (2.6%) of 153 Akodon sp.

Animals↗