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Biomedical subjects

A Navarrete

Publications and source records attributed to A Navarrete.

At least 19 recordsLinked to original sources
PubMed2006

Neuropharmacological profile of an ethanol extract of Ruta chalepensis L. in mice.

The effects of an ethanol extract of the aerial parts of Ruta chalepensis on the central nervous system (CNS) and LD(50) determination were studied in mice. A crude extract was given systemically and its effects were tested on pentylenetetrazole (PTZ)-induced seizures, sodium pentobarbital-induced hypnosis, exploratory activity, anxiety and nociception. Results from the experimental models tested showed: (1) a delay in the onset of seizures and a dose-dependent suppression in the tonic phase and mortality induced by PTZ; (2) a prolongation of the time of sodium pentobarbital-induced hypnosis; (3) a significant attenuation in the anxiety-response and (4) a reduction in the licking time and shaking behavior in the formalin-induced nociception test. The sedative-hypnotic potentiation, anxiolytic, anticonvulsant and antinociceptive effects suggest that Ruta chalepensis induces a depressant activity on the CNS.

Animals↗
PubMed2006

Quantification of parthenolide in Tanacetum species by LC-UV/LC-MS and microscopic comparison of Mexican/US feverfew samples.

LC-UV and LC-MS methods have been developed which permit the analysis of parthenolide in different Mexican/US feverfew samples and commercial products. The study was undertaken to confirm the presence of parthenolide in Mexican plant samples and its comparison with US feverfew samples. The best results were obtained with a Phenomenex Luna C18 (2) column using gradient mobile phase of water and acetonitrile:methanol (9 : 1). Elution was run at a flow rate of 1.0 mL per min and ultraviolet detection at 210 nm. The results obtained using LC-UV were comparable to those obtained using LC-MS. Parthenolide was detected in all the samples analyzed and is the major chemical constituent of feverfew. The samples collected in Oaxaca, Mexico (0.28%) and Puebla, Mexico (0.25%) showed the highest content of parthenolide. All Parthenium samples were also examined under light and fluorescent microscopy.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2001

Diaminoindanes as microsomal triglyceride transfer protein inhibitors.

The synthesis and biological activities of biarylamide-substituted diaminoindanes as microsomal triglyceride transfer protein (MTP) inhibitors are described. One of the more potent compounds, 8aR, inhibited both the secretion of apoB from Hep G2 cells and the MTP-mediated transfer of triglycerides between synthetic acceptor and donor liposomes with IC(50) values of 0.7 and 70 nM, respectively. In normolipidemic rats and dogs, oral administration of 8aR dose-dependently reduced both plasma triglycerides and total cholesterol. Moreover, in rats and dogs, 8aR also prevented the postprandial rise in plasma triglycerides following a bolus administration of a fat load. Because MTP inhibitors decrease very low density lipoprotein assembly in the liver, the potential for hepatic lipid accumulation was evaluated. In normolipidemic rats, hepatic cholesterol and triglyceride contents were dose-dependently increased by 8aR. However, hepatic lipid accumulation resulted in negligible change in total liver weight and was reversible after withdrawal of the compound.

Animals↗
PubMed2001

Amoebicidal and giardicidal compounds from the leaves of Zanthoxylum liebmannianun.

The crude ethanol extract from the leaves of Zanthoxylum liebmannianum exhibited inhibitory effect on the reproduction of trophozoites of Entamoeba histolytica (IC(50)=3.48 microg/ml) and Giardia lamblia (IC(50)=58.00 microg/ml). From this extract, asarinin, hyperin, beta-sitosterol, and beta-sitosterol glucoside were isolated. Among them, asarinin was the most active with IC(50) values of 19.86 microg/ml for E. histolytica and 35.45 microg/ml for G. lamblia. The remaining compounds showed moderate activity against both parasites.

Amebicides↗
PubMed2001

Anticonvulsant properties and bio-guided isolation of palmitone from leaves of Annona diversifolia.

The activity-guided fractionation of the ethanol extract of leaves of Annona diversifolia Saff., led to the isolation of palmitone (16-hentriacontanone) as the only anticonvulsant active compound. This aliphatic ketone was highly effective to diminish pentylenetetrazole (PTZ)-induced clonic-tonic seizures and toxicity. Also, it produced a prolongation of the latency for onset of seizures and a reduction of the death rate produced by 4-aminopyridine (4-AP) and bicuculline (BIC). However, it was inactive to inhibit the kainic acid (KA)- and strychnine (STC)-induced seizures. Palmitone did not produce motor incoordination and loss of righting reflex which are used as signs of neurological impairment. Palmitone (ED50 = 1.85 mg/kg) proved to be a more potent antiepileptic drug against the PTZ-induced seizures than etosuximide (ED50 = 59.6 mg/kg), sodium valproate (ED50 = 63 mg/kg), and carbamazepine (ED50 > 300 mg/kg) and it was only four-fold less potent than diazepam (ED50 = 0.48 mg/kg). The pharmacological profile of palmitone suggests that this compound could be acting on the GABAergic inhibitory system.

Animals↗
PubMed2000

Activated ADP-ribosylation factor assembles distinct pools of actin on golgi membranes.

The small GTP-binding protein ADP-ribosylation factor (ARF) has been shown to regulate the interaction of actin and actin-binding proteins with the Golgi apparatus. Here we report that ARF activation stimulates the assembly of distinct pools of actin on Golgi membranes. One pool of actin cofractionates with coatomer (COPI)- coated vesicles and is sensitive to salt extraction and the plus end actin-binding toxin cytochalasin D. A second ARF-dependent actin pool remains on the Golgi membranes following vesicle extraction and is insensitive to cytochalasin D. Isolation of the salt-extractable ARF-dependent actin from the Golgi reveals that it is bound to a distinct repertoire of actin-binding proteins. The two abundant actin-binding proteins of the ARF-dependent actin complex are identified as spectrin and drebrin. We show that drebrin is a specific component of the cytochalasin D-sensitive, ARF-dependent actin pool on the Golgi. Finally, we show that depolymerization of this actin pool with cytochalasin D increases the extent of the salt-dependent release of COPI-coated vesicles from the Golgi following cell-free budding reactions. Together these data suggest that regulation of the actin-based cytoskeleton may play an important role during ARF-mediated transport vesicle assembly or release on the Golgi.

ADP-Ribosylation Factors↗
PubMed2000

L-type calcium channel activity regulates sodium channel levels in rat pituitary GH3 cells.

1. The effects of chronic pharmacological modulation of L-type Ca2+ channel activity on the cell surface expression of Na+ channels were examined in GH3 cells. 2. Prolonged inhibition (4-5 days) of L-channels with nimodipine caused a 50-60 % decrease in the peak amplitude of whole-cell Na+ currents recorded with the patch-clamp technique. On the contrary, prolonged exposure to the L-channel agonist Bay K 8644 induced an approximately 2.5-fold increase in peak Na+ current. In both cases, there were only minor changes in cell capacitance and no significant changes in Na+ channel gating properties. 3. Measurements of the specific binding of radiolabelled saxitoxin to intact cells showed that nimodipine treatment reduced the number of cell surface Na+ channels, whereas treatment with Bay K 8664 produced the opposite effect. The dual regulation of Na+ channel abundance explained the mentioned changes in Na+ current amplitude. 4. Plasma membrane Na+ channels had a half-life of approximately 17 h both in control cells and in cells treated with Bay K 8644, as estimated from the rate of decay of peak Na+ current after inhibition of protein synthesis with cycloheximide. Actinomycin D, an inhibitor of gene transcription, and also cycloheximide, occluded the stimulatory effect of Bay K 8644 on Na+ current density when measured over a 24 h period. 5. These findings indicate that the entry of Ca2+ through L-type channels influences in a positive way the number of functional Na+ channels in GH3 cells, and suggest that Ca2+ influx stimulates either Na+ channel gene expression or the expression of a regulatory protein that promotes translocation of pre-assembled Na+ channels into the plasma membrane.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed2000

Physiological Status and Community Composition of Microbial Mats of the Ebro Delta, Spain, by Signature Lipid Biomarkers.

Physiological status of microbial mats of the Ebro Delta (Tarragona, Spain) based on the extraction of lipids considered "signature lipid biomarkers" (SLB) from the cell membranes and walls of microorganisms has been analyzed. Data from a day-night cycle show significant differences in viable cells countings (PLFA cells counts) ranging from 1.5 x 10(10) to 5.0 x 10(10) cells g(-1) of sediment. Minimum values were observed at 18:00 and 6:00, when physicochemical conditions change drastically. The diversity of the microbial community was assessed by GC/MS analysis of phospholipid fatty acids (PLFA). The ratio of PLFA, representative of Gram-negative bacteria, comprises 47.8% of the total PLFA of the microbial mat community. The remaining PLFA was representative of Gram-positive (10.0%), anaerobic (5.7%), and eukaryotic microorganisms (5.7%), and other common lipids. Two different approaches were used as a comparative study to assess the physiological status of the microbial mats. Two parameters (cyclopropane fatty acids/omega7c monoenoic fatty acids, and measurement of the trans/cis monoenoic PLFA ratio) showed a minimum at midnight, suggesting the highest microbial activity. Higher values were observed at 18:00 and 6:00, coinciding with lower PLFA cell counts. </hea

Journal Article↗
PubMed2000

Isolation and identification of autochthonous microbiota from a granitic aquifer and its variation after the bottling process.

The autochthonous microbiota from a granitic aquifer in Spain were studied. Several bacterial strains were isolated and identified. The major components of the microbiota were Pseudomonas-like strains, Flavobacterium, Acinetobacter, and Alcaligenes. The variation in the number of microorganisms after the bottling process was studied. The initial bacterial population increased over the first 5 days after bottling. This increase was higher in samples from polyvinyl chloride bottles. Sonication usually increased the total cell counts. As expected, most of the autochthonous microbiota were not detected in the viable cell counts.

Colony Count, Microbial↗
PubMed2000

Mineralogical composition and biomass studies of the microbial mats sediments from the Ebro Delta, Spain.

The mineral composition of the microbial mats at La Banya spit was studied. The spit is formed by a narrow sand bar and a peninsula and is located south of the main body of the Ebro Delta (Tarragona, Spain). Although quartz was the predominant mineral component in all sampling sites, clay, feldspars, calcite, aragonite, halite, dolomite and gypsum were also found. An increase in both the fine material (clay) and the halite content was observed in the sites influenced by nearby salterns. The amount of each mineral did not differ significantly along a 55 cm deep profile, except for halite and aragonite, which reached a maximum in the surface and decreased with depth. Dolomite, which ranged from 0.5 to 5% (w/w), is a possible indicator of sulfate-reducing bacteria activity in the past. Organic carbon and total nitrogen were quantified for biomass assessment. Total nitrogen ranged from 0.1 to 0.56% in the uppermost layer, where the microbial mat is active, but was undetectable at deeper layers. Organic carbon ranged from 1 to 5.5% in the active microbial mat layers and decreased to 0.3% at deeper layers. During the summer, both organic carbon and total nitrogen contents (biomass) of the microbial mat samples from some sites increase, whereas other sites show constant concentrations throughout the year, and others have a fluctuant biomass content.

Biomass↗
PubMed1999

Ingestion of chilli pepper (Capsicum annuum) reduces salicylate bioavailability after oral asprin administration in the rat.

The bioavailabilities of aspirin (acetylsalicylic acid) and of salicylic acid were studied in male Wistar rats after acute and chronic administration of a Capsicum annuum extract, containing 100 mg of capsaicin per gram. With a single administration of 100 mg/kg of the extract, aspirin blood levels remained unchanged, but salicylic acid bioavailability was reduced in 44% compared with control animals. With a single administration of 300 mg/kg of the extract, aspirin blood levels were undetectable while salicylic acid bioavailability was reduced in 59%. Chronic administration once daily for 4 weeks of 100 and 300 mg/kg of the extract resulted in undetectable aspirin blood levels, while salicylic acid bioavailability was reduced in 63 and 76%, respectively, compared with controls. Results show that Capsicum ingestion reduces oral drug bioavailability, likely as a result of the gastrointestinal effects of capsaicin.

Administration, Oral↗
PubMed1998

Oxygenic photosynthesis and respiratory activity in microbial mats of the ebro delta, spain, by oxygen exchange method

Photosynthetic and respiratory activities at low light intensities (300 &mgr;E m-2 s-1) in the microbial mats of the Ebro Delta were measured by the oxygen exchange method in the laboratory. The response to H2S concentration, a significant factor in the dynamics of that ecosystem, was assessed. Total photosynthesis reached 23. 78-28.17 &mgr;g O2 cm-2 h-1. Photosynthetic activity was not significantly different at the two temperatures tested. Respiratory activity reached a consumption of 6.95-8.56 &mgr;g O2 cm-2 h-1 at 25 degreesC and 11.42-11.70 &mgr;g O2 cm-2 h-1 at 35 degreesC. The Q10 value for respiration was 1.37-1.64. Oxygen production in Microcoleus chthonoplastes, the most abundant cyanobacterium in those microbial mats, was highly resistant to sulfide inhibition. Concentrations less than 0.02 mM sulfide did not affect the rate of photosynthesis. Concentrations up to 0.1 mM sulfide caused different degrees of partially reversible inhibition, with a maximum of 67% at 0.78 mM sulfide. Primary production (g C assimilated/m2/year) in those microbial mats was also assessed and compared with data from other ecosystems.

Journal Article↗
PubMed1998

[Is the exercise test performed after myocardial infarct really useful in improving prognosis? Arguments in favor].

The evaluation of risk after myocardial infarction accomplishes two objectives: a) selecting patients with high-risk for coronary angiography and revascularization, and b) identifying low-risk patients to avoid unnecessary laboratory investigation and revascularization procedures. Currently, patients eligible for exercise test are those with no evidence of heart failure or angina, and with a preserved left ventricular function. Overall prognosis for such patients, especially if they were thrombolyzed, is very good. In this setting, in contrast to that pointed out in previous reports, the positive predictive value of exercise electrocardiography is very low (i.e., a patient with S-T depression has a probability of cardiac death in the ensuing year of only 4% vs 2% if the test is negative). This suggests that a routine postinfarction exercise test is inefficient from a prognostic point of view. However, a recent study has shown that thrombolyzed patients with a positive response to the exercise test, have a significantly lower rate of reinfarction and unstable angina when they undergo myocardial revascularization. Mortality rate, as it was low in the study population, was unchanged by the use of revascularization procedures. We conclude that, in spite of the limitations pointed out, there are at least two reasons to continue performing exercise tests in all uncomplicated infarctions: a) a negative test, due to its high negative predictive value for adverse events, reassures the patient and his family and prompts an early discharge, and b) some patients, despite an uncomplicated in-hospital evolution, have a "strong" positive response that suggests multivessel disease and a possible benefit from myocardial revascularization.

Coronary Angiography↗
PubMed1998

Cosmopolitan distribution of the large composite microbial mat spirochete, Spirosymplokos deltaeiberi.

Inocula from organic-rich black muds immediately underlying intertidal laminated microbial mats dominated by Microcoleus chthonoplastes yielded large, variable diameter spirochetes. These unusual spirochetes, previously reported only from the Alfacs Peninsula at the delta of the Ebro river in northeast Spain, contain striking arrays of cytoplasmic granules packed into their protoplasmic cylinders. On several occasions, both in summer and winter, the huge spirochetes were recognized in samples from mats growing in the Sippewissett salt marsh at Woods Hole Massachusetts. They were also seen in similar samples from microbial mats at North Pond, Laguna Figueroa, Baja California Norte, Mexico. The identity of these spirochetes was confirmed by electron microscopy: number and disposition of flagella, composite structure, measurements of their distinctive cytoplasmic granules. The granules, larger, more conspicuous and present in addition to ribosomes, are hypothesized to contain ATPases. As culture conditions worsen, these spirochetes retract into membrane-bounded round bodies in which they form refractile inclusions. From morphology and behavior we conclude the North American spirochetes from both Atlantic and Pacific intertidal microbial mats are indistinguishable from those at the delta of the Ebro river. We conclude a cosmopolitan distribution for Spirosymplokos deltaeiberi.

Massachusetts↗
PubMed1996

Anthelmintic properties of alpha-sanshool from Zanthoxylum liebmannianum.

The decoction of the stem bark of Zanthoxylum liebmannianum (Engelm.) P. Wilson (Rutaceae) decreased the count of intestinal nematode eggs in naturally infected sheep. In addition, the chloroformic extract was toxic to Ascaris suum. Fractionation of the organic extract guided by the Ascaris suum lethality test led to the isolation of alpha-sanshool (LC50 = 83.4 x 10(-5)M) as the only active compound. On the other hand, alpha-sanshool induced tonic-clonic seizures when it was injected intraperitoneally to mice. This finding could be a warning regarding the potential toxicity of this plant.

Amides↗
PubMed1996

[The journal of the Spanish Society of Microbiology, 1945-1995].

The official journal of the Spanish Society for Microbiology (SEM) was first published in 1947, under the name Microbiología Española. Until 1984 the journal was published by the SEM jointly with the Institute < > (from the National Research Council, CSIC). In 1985 SEM started by itself to publish a new journal named Microbiología SEM, which may be considered the continuation of the former. From 1985 on the journal has increased both the quality and variety of its articles. At the beginning, most articles were in Spanish. Gradually, articles in English have been majority, to increase international readership. Currently the journal is published quarterly, with more than 500 pages per year.

Bibliometrics↗
PubMed1995

The anatomical substrates for language and hemispheric specialization.

Three main lines of investigation are discussed in this paper: (1) the comparison between the anatomical arrangement of the language areas and the large-scale neurocognitive cortical networks partly involved in active or working memory; (2) the relations between hemispheric specialization and the development of interhemispheric communication; and (3) the analysis of individual differences in brain organization for language. The hypothesis and evidence presented stem from work being performed in our laboratories.

Cerebral Cortex↗