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Biomedical subjects

E Núñez

Publications and source records attributed to E Núñez.

At least 19 recordsLinked to original sources
PubMed2006

Health-related quality of life and costs in patients with osteoarthritis on waiting list for total knee replacement.

OBJECTIVES: To determine: (1) health-related quality of life (HRQL) in patients with severe osteoarthritis (OA) on a waiting list (WL) for total knee replacement (TKR) and to compare it with general Spanish reference population values (RPVs); (2) the influence of sociodemographic and clinical variables on HRQL dimensions and (3) the use and cost of resources related to knee OA. METHODS: Cross-sectional study. HRQL was measured by Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Medical Outcomes Study 36 Item Short Form Health Survey (SF-36) questionnaires. Sociodemographic and disease characteristics, body mass index, pharmacological treatment and the cost and use of economic resources related to knee OA during the 6-months previous to baseline were recorded. Relationships were analyzed using linear regression models. RESULTS: One hundred consecutive outpatients (71 female, mean age 71+/-6.89 years, mean disease duration 11.84+/-10.52 years) were included. Patients showed worse HRQL measured by SF-36 than the reference population, mainly in physical function, physical role and bodily pain dimensions (P<0.05). A low number of visits to physicians were recorded (mean 0.62+/-1.04). Total mean direct medical costs were 200.24 euro (95%CI 167.08-233.40) and total mean direct non-medical costs were 1234.87 euro (95%CI 812.74-1657.00). CONCLUSIONS: The HRQL of patients on a WL is worse than that of the reference population. The main costs of these patients were on non-medical resources, mainly due to functional limitations and loss of autonomy. The results suggest little compliance with knee OA management guidelines.

Aged↗
PubMed2006

Prognostic value of leukocytosis in acute coronary syndromes: the cinderella of the inflammatory markers.

In recent years, numerous studies have validated the role of inflammation in the pathogenesis of atherosclerosis. Several of such studies have produced compelling evidence that inflammation participates in both, the initiation and perpetuation of the atherosclerotic process. Furthermore, epidemiological observations have found basal white blood cell (WBC) count is strongly associated with future cardiovascular disease (CVD), highlighting the participation of leukocytes in the pathogenesis of the ischemic damage that occurred during an acute coronary event, in particularly during the acute myocardial infarction (MI). Fundamentally, an acute MI triggers a systemic response to a necrotic insult characterized by leukocytosis and acute-phase protein synthesis. In this setting, elevated WBC count plays a central role in the reparative process that takes place to replace the necrotic tissue for collagen. In addition to be a proxy for the intensity of the peri-infarction inflammatory response, recent evidence has also shown that an elevated WBC counts, measured during the acute phase of MI, to be associated with adverse outcomes. This relationship holds true even when adjusting for classical prognostic variables some of which are surrogates for the extension of the infarcted-area. WBC count prognostic value in absence of necrosis marker elevation (like unstable angina), however, remains unclear and controversial. Additionally, and essentially due to its simplicity, cost-effectiveness and wide availability, WBC count has drawn the attention of researchers as a potential stratification tool in acute coronary syndromes (ACS). However, a formal comparison is needed between WBC count with other inflammatory markers such high-sensitive C-reactive protein to fully characterize its diagnostic accuracy.

Biomarkers↗
PubMed2004

Role of the endocannabinoid system in Alzheimer's disease: new perspectives.

The role of the endocannabinoid system in several diseases is currently under intense study. Among these, Alzheimer's disease may be a new promising area of research. We have recently reported the existence of profound changes in the location and density of several elements of this system in Alzheimer's disease tissue samples, indicating that a non-neuronal endocannabinoid system is up-regulated in activated glia. Additional data from other groups suggest that glial cells may be important elements in the regulation of endocannabinoid system activity, both in health as in disease. Some of these aspects are briefly discussed in the present review.

Alzheimer Disease↗
PubMed2002

Biomonitoring of metal deposition in northern Spain by moss analysis.

The results of the first survey carried out in northern Spain to determine atmospheric deposition of metals by analysis of terrestrial mosses, are described. Samples of different mosses, mainly Hypnum cupressiforme and Scleropodium purum, were collected from 134 sampling sites, between 1995 and 1996. Levels of Al, As, Cr, Cu, Fe, Hg, Ni, Pb and Zn, were determined by flame atomic absorption or atomic fluorescence spectrophotometry. Regression analysis was used to compare the capacity of the selected moss species to accumulate the elements, and intercalibration of accumulation in these species was carried out where necessary. Distribution maps were prepared to allow the zones most affected by metal deposition to be identified and to relate this to known sources of contamination: electricity power stations and other industries (e.g. Hg and Ni), edaphic contamination (e.g. Al and Cr) and road traffic (Pb). Background levels of metals in each species were also determined for the study area.

Bryopsida↗
PubMed2001

Substrate-induced conformational changes of extracellular loop 1 in the glycine transporter GLYT2.

The neurotransmitter glycine is removed from the synaptic cleft by two Na(+)-and Cl(-)-dependent transporters, the glial (GLYT1) and neuronal (GLYT2) glycine transporters. GLYT2 lacks a conserved cysteine in the first hydrophilic loop (EL1) that is reactive to [2-(trimethylammonium)ethyl] methanethiosulfonate (MTSET) in related transporters. A chimeric GLYT2 (GLYT2a-EL1) that contains GLYT1 sequences in this region, including the relevant cysteine, was sensitive to the reagent, and its sensitivity was decreased by co-substrates. We combined cysteine-specific biotinylation to detect transporter-reagent interactions with MTSET inactivation assays and temperature dependence analysis to study the mechanism by which Cl(-), Na(+), and glycine reduce methanethiosulfonate reagent inhibition. We demonstrate a Na(+) protective effect rather than an increased susceptibility to the reagent exerted by Li(+), as reported for the serotonin transporter. The different inhibition, protection, and reactivation properties between GLYT2a-EL1 and serotonin transporter suggest that EL1 is a source of structural heterogeneity involved in the specific effect of lithium on serotonin transport. The protection by Na(+) or Cl(-) on GLYT2a-EL1 was clearly dependent on temperature, suggesting that EL1 is not involved in ion binding but is subjected to ion-induced conformational changes. Na(+) and Cl(-) were required for glycine protection, indicating the necessity of prior ion interaction with the transporter for the binding of glycine. We conclude that EL1 acts as a fluctuating hinge undergoing sequential conformational changes during the transport cycle.

Amino Acid Sequence↗
PubMed2001

Urea equilibrium unfolding of the major core protein of the retrovirus feline immunodeficiency virus and its tryptophan mutants.

Circular dichroism and fluorescence spectroscopy have been employed to study the urea unfolding mechanism of a recombinant form of the major core protein of feline immunodeficiency virus (FIV-rp24) and its native tryptophan mutants. The equilibrium denaturation curves indicate the existence of two transitions. The first unfolding transition most likely reflects the denaturation of the carboxy-terminal region of FIV-rp24. Consequently, the second transition, where the changes in fluorescence are produced, should reflect the denaturation of the amino-terminal region. If the intermediate observed upon urea denaturation is an on-pathway species, the data described herein can reflect the sequential and independent loss of structure of the two domains that this type of proteins possesses.

Circular Dichroism↗
PubMed2001

Calcium- and syntaxin 1-mediated trafficking of the neuronal glycine transporter GLYT2.

Previously we demonstrated the existence of a physical and functional interaction between the glycine transporters and the SNARE protein syntaxin 1. In the present report the physiological role of the syntaxin 1-glycine transporter 2 (GLYT2) interaction has been investigated by using a brain-derived preparation. Previous studies, focused on syntaxin 1-transporter interactions using overexpression systems, led to the postulation that syntaxin is somehow implicated in protein trafficking. Since syntaxin 1 is involved in exocytosis of neurotransmitter and also interacts with GLYT2, we stimulated exocytosis in synaptosomes and examined its effect on surface-expression and transport activity of GLYT2. We found that, under conditions that stimulate vesicular glycine release, GLYT2 is rapidly trafficked first toward the plasma membrane and then internalized. When the same experiments were performed with synaptosomes inactivated for syntaxin 1 by a pretreatment with the neurotoxin Bont/C, GLYT2 was unable to reach the plasma membrane but still was able to leave it. These results indicate the existence of a SNARE-mediated regulatory mechanism that controls the surface-expression of GLYT2. Syntaxin 1 is involved in the arrival to the plasma membrane but not in the retrieval. Furthermore, by using immunogold labeling on purified preparations from synaptosomes, we demonstrate that GLYT2 is present in small synaptic-like vesicles. GLYT2-containing vesicles may represent neurotransmitter transporter that is being trafficked. The results of our work suggest a close correlation between exocytosis of neurotransmitter and its reuptake by transporters.

Amino Acid Transport Systems, Neutral↗
PubMed2001

Cloning, expression, and purification of histidine-tagged preS domains of hepatitis B virus.

The preS domains of the hepatitis B virus are hydrophilic polypeptides that have been implicated, among other functions, in the binding of the virus to hepatocytes and in the induction of virus-neutralizing antibodies. A method of overproducing the preS domains of two different subtypes, adw and ayw, has been developed by adding a 6x His tag at the carboxy-terminal end of the polypeptides. Codons for the 6x His were added in reverse primers used to amplify the corresponding cDNAs. The polymerase chain reaction products were cloned into the expression vectors pET-3d (subtype ayw) and pT7-7 (subtype adw), under the control of the inducible bacteriophage T7 RNA polymerase promoter. Upon induction with isopropyl-beta-d-thiogalactopyranoside, proteins were overexpressed and purified by affinity chromatography on a Ni-nitrilotriacetic acid agarose column. This method yielded 20-40 mg of highly pure and very stable proteins per liter of cell culture. Circular dichroism and fluorescence spectroscopy of isolated preS-his-ayw and preS-his-adw, as well as their ability to bind polymerized human serum albumin, indicate that the 6x His tag does not modify the native-like conformation and, therefore, they may be considered as useful tools to study the function of these viral polypeptide regions.

Amino Acid Sequence↗
PubMed2000

Differential effects of the tricyclic antidepressant amoxapine on glycine uptake mediated by the recombinant GLYT1 and GLYT2 glycine transporters.

We examined the effects of nine different tricyclic antidepressant drugs on the glycine uptake mediated by the glycine transporter 1b (GLYT1b) and glycine transporter 2a (GLYT2a) stably expressed in human embryonic kidney 293 cells. Desipramine, imipramine, clomipramine, nomifensine and mianserin had no effect on the activity of the glycine transporters. Doxepin, amitriptyline and nortriptyline inhibited the two transporter subtypes to a similar extent. Amoxapine displayed a selective inhibition of GLYT2a behaving as a 10 fold more efficient inhibitor of this isoform than of GLYT1b. Kinetic analysis of the initial rates of glycine uptake by GLYT2a as a function of either glycine, chloride or sodium concentration, in the absence and presence of amoxapine indicated that amoxapine behaved as a competitive inhibitor of both glycine and chloride and a mixed-type inhibitor with respect to sodium. A kinetic model was developed which explains adequately these data, and gives information about the order of binding of sodium and chloride ions to GLYT2a. Our results may contribute to the development of the glycine transporter pharmacology. Additionally, the inhibition of the glycine uptake by GLYT2 is suggested to have some role in the sedative and psychomotor side effects of amoxapine. British Journal of Pharmacology (2000) 129, 200 - 206

Algorithms↗
PubMed2000

Differential effects of ethanol on glycine uptake mediated by the recombinant GLYT1 and GLYT2 glycine transporters.

The effects of ethanol on the function of recombinant glycine transporter 1 (GLYT1) and glycine transporter 2 (GLYT2) have been investigated. GLYT1b and GLYT2a isoforms stably expressed in human embryonic kidney 293 (HEK 293) cells showed a differential behaviour in the presence of ethanol; only the GLYT2a isoform was acutely inhibited. The 'cut-off' (alcohols with four carbons) displayed by the n-alkanols on GLYT2a indicates that a specific binding site for ethanol exists on GLYT2a or on a GLYT2a-interacting protein. The non-competitive inhibition of GLYT2a indicates an allosteric modulation by ethanol of GLYT2a activity. Chronic treatment with ethanol caused differential adaptive responses on the activity and the membrane expression levels of these transporters. The neuronal GLYT2a isoform decreased in activity and surface expression and the mainly glial GLYT1b isoform slightly increased in function and surface density. These changes may be involved in some of the modifications of glycinergic or glutamatergic neurotransmitter systems produced by ethanol intoxication.

Alcohols↗
PubMed1999

Fusogenic activity of hepadnavirus peptides corresponding to sequences downstream of the putative cleavage site.

Sequence homology between the amino-terminal region of the S protein of hepatitis B Virus (HBV) and known fusion peptides from retroviruses and paramyxoviruses led us to propose that this region might be equally involved in the initial infective steps of hepadnaviruses. In fact, we showed that a synthetic peptide corresponding to the N-terminus region of the S protein of HBV had membrane-interacting properties and was able to induce liposome fusion adopting an extended (beta-sheet) conformation (Rodríguez-Crespo et al., 1996, 1995). We describe herein studies on the interaction of peptides derived from the N-terminal region of the S protein of duck (DHBV: Met-Ser-Gly-Thr-Phe-Gly-Gly-Ile-Leu-Ala-Gly-Leu-Ile-Gly-Leu-Leu) and woodchuck hepatitis B viruses (WHV: Met-Ser-Pro-Ser-Ser-Leu-Leu-Gly-Leu-Leu-Ala-Gly-Leu-Gln-Val-Val) with liposomes. These peptides were able to induce to a different extent aggregation, lipid mixing, and leakage of internal aqueous contents from both neutral and negatively charged phospholipid vesicles in a concentration-dependent and pH-independent manner. Fluorescence depolarization of 1,6-diphenyl-1,3,5-hexatriene-labeled vesicles indicated that both peptides become inserted into the hydrophobic core of the lipid bilayer. Circular dichroism studies indicated that the DHBV peptide adopts an extended conformation in the presence of lipids, whereas the WHV peptide displays a high content of alpha-helical conformation. Therefore, these results extend our previous findings obtained for human hepatitis B virus to other members of the hepadnavirus family and suggest that this region of the S protein is important in the initial steps of the infective cycle.

Amino Acid Sequence↗
PubMed1999

Circular dichroism and fluorescence spectroscopic properties of the major core protein of feline immunodeficiency virus and its tryptophan mutants. Assignment of the individual contribution of the aromatic sidechains.

The gene coding for the major capsid protein of feline immunodeficiency virus (FIV) has been cloned into the expression vector pQE60, which allows protein purification by affinity chromatography on a nitrilotriacetic acid/Ni/agarose column. The gene was expressed in Escherichia coli and the resultant soluble protein (FIV-rp24) purified to electrophoretic homogeneity. The amino-acid composition of the recombinant protein is almost identical to that predicted from the DNA sequence. This protein has two tryptophan residues at positions 40 and 126 that have been replaced by phenylalanine by site-directed mutagenesis to obtain two single mutants and a double mutant. Circular dichroism and fluorescence spectroscopy were employed to study the structural features of FIV-rp24 protein and its tryptophan mutants. The analysis of the CD spectra indicated that alpha-helix is the major secondary structural element (48-52%) and that the overall three-dimensional structure is not modified by the mutations. The fluorescence emission spectra showed that both tryptophan residues occupy a highly hydrophobic environment. Moreover, the different tyrosine fluorescence intensities of wild-type and mutant proteins are indicative of the existence of resonance energy transfer processes to nearby tryptophan. The individual contributions of each tryptophan residue to the spectroscopic properties of the wild-type protein were obtained from the spectra of all these proteins. Thermal denaturation studies indicate that the two tryptophan residues do not contribute equally to the stabilization of the three-dimensional structure.

Amino Acid Sequence↗
PubMed1998

An overview of the marine food poisoning in Mexico.

In the course of the last decade, huge events related to harmful algal blooms (HAB) have severely affected the environment in Mexico, even causing several human casualties. The tally of the toxins known up to date in Mexican waters includes: neurotoxin shellfish poisoning (NSP), paralytic shellfish poisoning (PSP), amnesic shellfish poisoning (ASP), tetrodotoxin (TTX) or puffer fish poisoning, ciguatera fish poisoning (CFP) and diarrhetic shellfish poisoning (DSP). Actual epidemiological figures profoundly modified the trends manifested on previous decades. Notwithstanding that the red tides are a long time known phenomena in Mexican coasts, no regular observation of the marine environment has been set up. Although there are monitoring activities for PSP toxins on the shellfish culturing facilities that are exploited for export to the U.S.A., these are only effectively applied on specific spots of the Mexican coasts, implying that the biggest part of the country coastal zones are not formerly surveyed. The misleads caused by the medical conception that food poisoning events are mainly due to microbial contamination, is among the factors why the marine food poisoning events are a neglected disease. In spite of the fact that no official statistics consider HAB related events as a subject of research or further monitoring by the health authorities, sporadic scientific documents related to poisoning events were produced in Mexico. An interesting picture is presented for most of the marine toxins mentioned. Trend and prognosis estimates made with such scarce information, provide a minimum measurement of the reality and urge the need for a permanent monitoring program on the Mexican coasts, a place with one of the greatest marine toxin diversity worldwide.

Animals↗
PubMed1998

Differential properties of two stably expressed brain-specific glycine transporters.

Clonal cell lines stably expressing the glial glycine transporter 1b (GLYT1b) and the neuronal glycine transporter 2 (GLYT2) from rat brain have been generated and used comparatively to examine their kinetics, ion dependence, and electrical properties. Differential sensitivity of the transporters to sarcosine is clearly exhibited by the clonal cell lines. GLYT2 transports glycine with higher apparent affinity than GLYT1b and is not inhibited by any assayed compound, as deduced by glycine transport assays and electrophysiological recordings. A sigmoidal Na+ dependence of the glycine uptake by the stable cell lines is observed, indicating the involvement of more than one Na+ in the transport process. A more cooperative behavior for Na+ of GLYT2 than GLYT1b is suggested. One Cl- is required for GLYT1b and GLYT2 transport cycles, although GLYT1b shows three times higher affinity for this ion than GLYT2. The number of expressed transporters was sufficient to allow electrophysiological recordings of the uptake current in the two stable cell lines. GLYT2 exhibits more voltage dependence in both its glycine-evoked current and its capacitive currents recorded in the absence of substrate.

Amino Acid Transport Systems, Neutral↗
PubMed1996

Immunomodulation of LPS ability to induce the local Shwartzman reaction.

Immunologically, the septic shock is a natural model of immunomediated vascular pathology where the interaction between cytokines and the endothelium mediates the syndrome and lethality. Tumour necrosis factor (TNF), a non-species-specific cytokine, has outstanding pleiotropic activities as an important mediator of the septic shock syndrome. In rabbits, passive immunization with anti-lipopolysaccharide (LPS) polyclonal antibodies prior to the intravenous (i.v.) injection of LPS inhibits the haemorrhagic necrotic lesion characteristic of the local Shwartzman reaction (an excellent localized in vivo correlate of the septic shock). Paradoxically, tested in an ex vivo assay (short-term whole human blood culture, stimulated with LPS), these antibodies mediated an increase in TNF production by mononuclear phagocytes and, in the rabbit model, they induced an increase in body temperature, as compared with the pre-immune reagent. Although anchoring of immune complexes containing LPS to receptors (Fc or C4b-C3b) on circulating monocytes may facilitate the access of LPS to these cells, access to localized, LPS-sensitized macrophages may be impaired. Consequently inhibition of the local Shwartzman reaction and increased TNF production in the ex vivo system were observed. Concordantly, the higher temperature in the passively immunized animals may be a consequence of a higher, immune complex-induced, systemic TNF production. These experimental results suggest that the use of anti-LPS immunoglobulins, as a potential immunotherapy for septic shock syndrome in vertebrates, may lead to increased TNF production, with adverse effects such as the pyrogenic.

Animals↗
PubMed1995

Phospholipid interactions of the putative fusion peptide of hepatitis B virus surface antigen S protein.

One of the first steps in the infective cycle of an enveloped virus consists of the fusion of the viral and cellular membranes. This process is usually achieved as a result of membrane destabilization brought about by a viral fusion peptide located at the amino terminus of one of the viral envelope glycoproteins. Previous sequence similarity studies by Rodríguez-Crespo et al. (Journal of General Virology 75, 637-639, 1994) have shown that a hydrophobic stretch in the amino-terminal sequence of the S protein of hepatitis B virus shares several characteristics with fusion peptides of retroviruses and paramyxoviruses. A 16 residue peptide with this sequence was synthesized and its interaction with liposomes characterized. This peptide was able to mediate vesicle aggregation, lipid mixing and liposome leakage in a pH dependent manner at concentrations ranging from 3.5 to 52.0 microM. These effects were specific for negatively charged phospholipid vesicles. The peptide was also able to haemolyse erythrocytes. This study supports the notion that the sequence might be important in the initial infective steps of this virus, interacting with the target membranes and bringing about their subsequent destabilization.

Amino Acid Sequence↗
PubMed1995

[Mercury in the hair of pregnant and lactating Chilean mothers].

Mercury-containing industrial waste has been released into the coastal waters of the Eighth Region of Chile for around two decades. This study, carried out from 1991 to 1993, sought to measure mercury concentrations in the hair of pregnant and lactating women from villages near the coast and in the interior of the region in order to examine the relationship between the concentration of mercury and seafood consumption. The survey questionnaire used in 1991 to determine seafood consumption did not ask about the frequency of consumption of fish, shellfish, and algae but only whether the women who were pregnant or breast-feeding consumed a minimum of one fish-based meal per week. The questionnaire used in 1992 and 1993 asked about the daily and weekly consumption of seafood in general (fish, shellfish, and algae). Spectrophotometry was used to determine the total mercury concentration in samples of 100 mg of hair from 153 pregnant and lactating women in 11 fishing villages of the Eighth Region where seafood is regularly consumed. None of the women had occupational exposure to mercury. Total mercury concentration was also determined in hair samples from a control group composed of 26 pregnant and lactating women from Pinto and El Carmen, villages in the interior of the same region where seafood was rarely eaten. The arithmetic mean of the total mercury concentration in hair was 1.81 mg/kg of body weight for the study group (standard deviation [SD] 1.52) and 0.42 mg/kg for the control group (SD 0.15)--a statistically significant difference (P < 0.01). Pairwise comparisons also revealed statistically significant differences (P < 0.05) between the mean for the interior group and the means for the women in the nine villages closest to the sources of the pollution, but not between the mean for the interior group and those for women in the two villages at the extreme north and south of the study zone, who lived farthest from the contaminated waters. The total mercury concentration in hair was significantly higher in women who indicated that they ate fish seven or more times per week; in those who said they ate fish, shellfish, or algae five or more times per week; and in those who had lived 20 or more years in their village. No statistically significant differences were found when the results were analyzed by age.

Adolescent↗