Biomedical subjects

S Pérez

Publications and source records attributed to S Pérez.

At least 19 recordsLinked to original sources

PubMed2006

Comparison of two extremity dosemeters based on LiF:Mg,Cu,P thin detectors for mixed beta-gamma fields.

Two types of thin LiF:Mg,Cu,P detectors, GR-200F and MCP-Ns, have been characterised for use in the design of an extremity dosemeter for mixed beta-photon radiation fields. Both detectors consist of an extremely thin layer of sensitive material with effective thicknesses of 5 and 8 mg cm(-2), respectively, held in a 5 mg cm(-2) PVC ring holder. Dosimetric performance was analysed according to the ISO 12794 standard and compared with 240 mg cm(-2) TLD-100 measurements. In particular, the energy response was obtained for ISO narrow X-ray spectra, (137)Cs, (60)Co, (204)Tl and (90)Sr/(90)Y. From these measurements a mean calibration factor was calculated to estimate H(p)(0.07). Subsequently, the performance of the dosemeters was checked for a set of 10 different mixed photon and beta-photon fields. The study shows that the proposed dosemeters can estimate H(p)(0.07) in a wide range of mixed beta-photon fields with a maximum deviation from the given dose of 30% and an overall uncertainty of the order of 25% (k = 1). However, the results also highlight a large variability among the different thin detectors and, thus, the standard TLD-100 material is recommended whenever the workplace does not include low-energy beta radiation.

Beta Particles↗

PubMed2006

Infectious haemolytic anaemia causes jaundice outbreaks in seawater-cultured coho salmon, Oncorhynchus kisutch (Walbaum), in Chile.

In the last 9 years, epizootics of an icterus condition has affected coho salmon, Oncorhynchus kisutch (Walbaum), reared in seawater cages in southern regions of Chile. At necropsy, fish from field cases exhibited signs of jaundice accompanied by pale light-brown livers and dark spleens. Histopathological and haematological results indicated that these fish presented haemolytic anaemia. After microbiological examination no bacterial or viral agents could be identified as aetiological agents of this disease. In an infectivity trial, coho salmon, Atlantic salmon, Salmo salar L., and rainbow trout, Oncorhynchus mykiss (Walbaum), were inoculated intraperitoneally with a filtrate of an organ homogenate (0.45 microm) from a diseased coho salmon and held for 60 days in tanks supplied with fresh water. The disease was only reproduced in coho salmon in which mortalities, beginning at day 23 post-inoculation (p.i.), reached a cumulative value of 24% at day 27 p.i. This condition was transmitted to non-inoculated cohabiting coho salmon suggesting that it is a waterborne disease. Thus, this icteric condition is caused by an infectious form of haemolytic anaemia, probably of viral aetiology, and coho salmon are more susceptible than either Atlantic salmon or rainbow trout.

Anemia, Hemolytic↗

PubMed2005

Anti-inflammatory activity of Lippia dulcis.

Lippia dulcis hexane and ethanol extracts were tested for its anti-inflammatory activity in several animal models. Hexane extract showed to be inactive, but the ethanol extract at doses of 400 mg/kg produced significant inhibition of carrageenan-induced paw oedema and reduced the weight of cotton pellet-induced granuloma, moreover, the topical application of 0.5 mg/ear of this extract inhibited the edema induced with TPA by 49.13%, an effect which is of less intensity than that produced by indomethacine at the same dose.

Animals↗

PubMed2005

Influence of the saturation chain and head group charge of phospholipids in the interaction of hepatitis G virus synthetic peptides.

Using the Langmuir technique, we have studied the properties at the air/water interface and the interaction of the hepatitis G virus synthetic peptide E1(53-66) and its palmitoyl derivative with membrane phospholipids. These phospholipids had different characteristics referring to the net charge and saturation of the acyl chain. The palmitoyl derivative was more stable at the air/water interface and in the kinetic at constant area measurements showed higher incorporation to the monolayer. The interaction was higher for saturated phospholipids and those with a negative net charge. When the peptides were in the subphase, they produced changes in the miscibility of mixed monolayers composed of DPPC/DPPG or DOPC/DOPG. It can be deduced from the results obtained that electrostatic interactions play a major role, but when the peptide is derivatized with the palmitoyl chain, hydrophobic interactions are added to the former ones. The interaction is also influenced by the saturation of the acyl chain.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed2004

Mu opioid control of the N-methyl-D-aspartate-evoked release of [3H]-acetylcholine in the limbic territory of the rat striatum in vitro: diurnal variations and implication of a dopamine link.

Using an in vitro microsuperfusion procedure, the release of newly synthesized [(3)H]-acetylcholine (ACh), evoked by N-methyl-D-aspartate (NMDA) receptor stimulation, was investigated in striosome-enriched areas and matrix of the rat striatum. The role of micro-opioid receptors, activated by endogenously released enkephalin, on the NMDA-evoked release of ACh was studied using the selective micro-opioid receptor antagonist, beta-funaltrexamine. Experiments were performed 2 (morning) or 8 (afternoon) h after light onset, in either the presence or absence (alpha-methyl-p-tyrosine, an inhibitor of dopamine synthesis) of dopaminergic transmission. As expected, based on the presence of micro-opioid receptors in striosomes, beta-funaltrexamine (0.1 nM, 10 nM and 1 microM) enhanced the NMDA (1 mM+10 microM D-serine)-evoked release of ACh in striosome-enriched areas but not in the matrix. Interestingly, these responses were significantly more pronounced in afternoon than in morning experiments. In the presence of alpha-methyl-p-tyrosine, the NMDA-evoked release of ACh was increased with similar amplitude in morning and afternoon experiments. However, in this condition (without dopamine transmission), the facilitatory effects of beta-funaltrexamine on the NMDA-evoked release of ACh were suppressed totally in the morning and only partially in the afternoon. The selective micro-opiate agonist, [D-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin (1 microM, coapplied with NMDA), was without effect on the NMDA-evoked release of ACh but abolished both dopamine-dependent (morning) and dopamine-independent (afternoon) responses of beta-funaltrexamine (10 nM and 1 microM).Therefore, in the limbic territory of the striatum enriched in striosomes, the micro-opioid-inhibitory regulation of ACh release follows diurnal rhythms. While dopamine is required for this regulation in the morning and the afternoon, an additional dopamine-independent process is present only in the afternoon.

Acetylcholine↗

PubMed2004

[Pulmonary hemorrhage and anti-phospholipid syndrome].

The presence of anti-phospholipid antibodies (anticardiolipin antibodies and lupus anticoagulant) associated to venous and/or arterial thrombotic phenomena and fetal losses define the anti-phospholipid syndrome. On rare occasions severe hypoprothrombinemia associated with this disease as a cause of hemorrhagic manifestations has been described. In addition very few cases of alveolar hemorrhage in anti-phospolipid syndrome (APS) have been described, being this complication usually related to microthrombosis and/or capillaritis of pulmonary vessels. We describe two patients without previous clinical manifestations of anti-phospholipid syndrome that showed pulmonary hemorrhage with anticardiolipin antibodies positivity. The first of them, a 33-year-old male, began his disease with low prothrombin time and the presence of antiprothrombin antibodies. In the biopsy by thoracoscopy the presence of pulmonary hemorrhage without capillaritis nor thrombotic phenomena was demonstrated, becoming evident certain clinical improvement and normalization of the prothrombin time after receiving immunosuppressive treatment but with persistence of the pulmonary hemorrhage 5 years later. The second case, a 89-year-old male, began his condition with bilateral lung infiltrates and hemoptysis, anticardiolipin antibodies positivity, and thrombopenia, with recurrence of the condition 1 year later. After other etiological possibilities were ruled out, and despite hemorrhagic trait in both patients, we consider that they should be in the clinical context of the anti-phospholipid syndrome, although at this time they did not meet the criteria recognized in order to diagnose this disease. Within the ampliable clinical spectrum of the anti-phospholipid syndrome we should take into account the pulmonary hemorrhage.

Adult↗

PubMed2003

[Strongyloides stercoralis in the south of Galicia].

Strongyloides stercoralis is the only parasite which can produce a chronic illness in humans, being through autoinfection. This nematode can also provoke death when patient's immunologic state deteriorates producing a massive hyper infection. The first patient with strongyloidiasis who has always lived in the Galician South area is described. The clinical picture consisted of unspecific cutaneous lesions and abdominal pain with severe peripheral eosinophilia (> 20,000/ml. The diagnosis was carried out observing the larvae in the fecal examination and was confirmed with a culture. Treatment with albendazole failed and the healing was reached with ivermectin. We must consider the possibility of strongyloidiasis because misdiagnosing these patients as eosinophilic gastroenteritis there would be a higher risk of hyperinfection if they are treated with corticosteroids.

Adult↗

PubMed2002

Cerebrospinal fluid and plasma concentrations of nitric oxide metabolites are increased in dementia with Lewy bodies.

We compared cerebrospinal fluid (CSF) and plasma concentrations of nitric oxide metabolites (NO(-)(x)) in 22 patients with dementia with Lewy bodies (DLB) and 13 matched controls. We found a pronounced increase in NO(-)(x) CSF and plasma levels in DLB patients. No changes were found in L-arginine and L-citrulline levels in CSF or plasma. There was no correlation between CSF and plasma levels and age, age of onset, duration of the disease or scores of the MiniMental State Examination. These findings reveal that excessive nitric oxide production may be related to the pathogenesis of DLB.

Aged↗

PubMed2002

Serum levels of coenzyme Q in patients with Lewy body disease.

The purpose of the present study was to compare serum levels of coenzyme Q(10) (CoQ(10)) and the coenzyme Q(10) cholesterol (CoQ(10)/cholesterol) ratio in 18 patients with Lewy body disease (LBD) with 20 matched controls. The mean serum coenzyme Q10 levels in patients with LBD were significantly reduced with respect to control group, however, no differences were found in CoQ(10)/cholesterol ratio between LBD patients and control group. There was no correlation among CoQ(10) and CoQ(10)/cholesterol ratio with age, age of onset, body mass index, duration of the disease or scores of the Mini Mental State Examination, UPDRS and Hoehn and Yahr stage. These results suggest the involvement of this enzimatic system in the pathogenic mechanism of LBD.

Age Factors↗

PubMed2002

Extremity and whole-body dosemeters for beta and beta gamma fields based on LiF:Mg,Cu,P thin detectors.

This study aims at proposing two TL dosemeters: one for the whole body and another for the extremities, for beta and gamma fields. Selected sensible material consists of 5 mg x cm(-2) LiF:Mg,Cu,P film (GR-200F) manufactured in China. Calibration was carried out according to ISO 4037-3, in terms of Hp(0.07), and dosimetric performance was analysed on the basis of IEC-1066 and ISO-12794 Standards. Experiments showed a satisfactory sensitivity of the proposed dosemeters for detecting beta radiation at protection levels and a very good energy response; thus, highly recommending their use for weakly penetrating radiation measurements. However, the homogeneity and the reproducibility of GR-200F are not found to be as reliable as in standard materials.

Arm↗

PubMed2002

New 3-[4-(aryl)piperazin-1-yl]-1-(benzo[b]thiophen-2-yl)propane derivatives with dual action at 5-HT1A serotonin receptors and serotonin transporter as a new class of antidepressants.

Some benzo[b]thiophene derivatives with different substituents in positions 3 and 5 have been synthesized in order to obtain new dual antidepressant drugs. Compounds derived from 2-acetyl-3-methylbenzo[b]thiophene or 2-acetyl-3,5-dimethylbenzo[b]thiophene were prepared with two different phenylpiperazines (2-methoxy and 2-hydroxyphenylpiperazine) and evaluated for in vitro 5-HT1A receptor affinity and serotonin reuptake inhibition by radioligand assays. Compound 1-(3,5-dimethylbenzo[b]thiophen-2-yl)-3-[4-(2-methoxyphenyl)piperazin-1- yl]propan-1-ol (II.2.a) shows good values (nM) for both activities: Ki = 85 for 5-HT1A receptor and Ki = 120 for serotonin transporter.

Antidepressive Agents↗

PubMed2002

New 3-[4-(3-substituted phenyl)piperazin-1-yl]-1-(benzo[b]thiophen-3-yl)propanol derivatives with dual action at 5-HT1A serotonin receptors and serotonin transporter as a new class of antidepressants.

In this paper a series of new 3-[4-(3-substituted phenyl)piperazin-1-yl]-1-(benzo[b]thiophen-3-yl)propanol derivatives is presented as a new class of antidepressant drugs with dual activity at 5-HT1A serotonin receptors and serotonin transporter. The 5-HT1A receptor and 5-HT transporter binding affinities of hydroxylic compounds 4 a-e have been determined. The new compounds present nanomolar affinity for both activities, and 1-(benzo[b]thiophen-3-yl)-3-[4-(3-methoxyphenyl)piperazin-1-yl]propan-1-ol (4d) shows values (nM) of Ki = 86 for 5-HT1A receptors and Ki = 76 for the serotonin transporter, respectively.

Antidepressive Agents, Second-Generation↗

PubMed2001

Quantitative analysis of polycyclic aromatic hydrocarbons in sewage sludge from wastewater treatment plants.

Polycyclic aromatic hydrocarbons (PAHs) are an important group of organic contaminants present in sewage sludge. Due to their persistence and toxic potential, information about their presence in sewage sludge is needed in order to assess applicability on agricultural land. A method for the gas chromatographic-mass spectrometric (GC-MS) determination was developed and applied to the trace determination of PAHs present in sewage sludge samples from six wastewater treatment plants (WWTPs) differing in the type of treatment and the origin of wastewater. PAHs were extracted from freeze-dried samples by a dichloromethane-methanol (2:1) mixture in a sonication bath. The sludge extracts were cleaned-up by an alumina column. The method showed recovery values varying from 60 to 98%. Four surrogate standards ([2H8]naphthalene, [2H10]anthracene, [2H12]benzo[a]anthracene, and [2H12]benzo[ghi]perylene) were used for quantitation by GC-MS. A reference sludge sample was analysed in order to validate the method. The sum of the 16 US Environmental Protection Agency PAHs analysed in the sewage sludge samples varied from 1.13 to 5.52 mg/kg. No significant difference between the different WWTPs was found.

Calibration↗

PubMed2001

The diluted aqueous solvation of carbohydrates as inferred from molecular dynamics simulations and NMR spectroscopy.

The purpose of this paper is to review our understanding of the dilute hydration (aqueous solvation) behaviour of disaccharide compounds. To this end we discuss and scrutinize the results that have been obtained for the three model disaccharides: maltose, sucrose and trehalose from experimental NMR studies and from theoretical molecular dynamics studies in explicit aqueous solutions. The focus is on the description of molecular hydration features that will influence macroscopic entities such as diffusion and relaxation: residence times of hydration waters, hydration numbers and hydration densities. The principles of molecular dynamics simulation are briefly outlined while a detailed presentation is given of the key features that characterise hydration: the solvation of the glycosidic linkage, the radial hydration of the solute, the water density anisotropy around the solute, the residential behaviour of water molecules in the periphery of the solute, and rotational and translational diffusion coefficients. With respect to the use of NMR in characterising the structure and dynamics of the hydration, the hydrodynamic theory of rotational and translational diffusion of biomolecules as well as the use of pulse field gradient spin echo experiments are briefly presented. The NMR-defined rotational diffusion coefficients (D(r)) and the experimentally determined translational diffusion (D(t)) coefficients are reported for 4% (w/w) solutions of sucrose, trehalose and maltose. These results are compared with theoretical data obtained from molecular dynamics simulations of sucrose, trehalose and maltose under identical conditions (concentration, temperature, etc.). With our present level of knowledge we can propose that although carbohydrates share a number of hydration characteristics, evidence is accumulating in support of the notion that it is not the amount or overall hydration but rather the detailed individual carbohydrate-water interaction that is likely to determine carbohydrate structure and functionality.

Carbohydrate Conformation↗

PubMed2001

Experimental proof for the structure of a thrombin-inhibiting heparin molecule.

Kinetic studies of thrombin inhibition by antithrombin in the presence of heparin have shown that thrombin binds to heparin in a preformed heparin-antithrombin complex. To study the relative position of the thrombin binding domain and the antithrombin binding domain on a heparin molecule we have designed and synthesized heparin mimetics, which structurally are very similar to the genuine polysaccharide. Their inhibitory properties with respect to factor Xa and thrombin provide experimental evidence that in heparin the thrombin binding domain must be located at the nonreducing end of the antithrombin binding domain to observe thrombin inhibition. As expected, factor Xa inhibition is not affected by elongation of the antithrombin binding pentasaccharide sequence, regardless of the position in which this elongation takes place.

Antithrombins↗

PubMed2001

Platelet activating factor increases ciliary activity in the hamster oviduct through epithelial production of prostaglandin E2.

We investigated the signal transduction mechanisms associated with an increase in ciliary beat frequency (CBF) produced by platelet activating factor (PAF) in oviductal ciliated cell cultures. In the range of concentrations similar to that produced by preimplantation embryos, PAF increased the CBF in a dose-dependent manner. The addition of PAF and prostaglandin E2 (PGE2) to the cultures produced a synergic increase of ciliary beating, suggesting that PAF and PGE2 signal transduction pathways may be associated. To demonstrate this hypothesis, cyclooxygenase-2 (COX-2) was selectively blocked by a specific inhibitor, NS-398, and the PAF-induced CBF increase was abolished. Moreover, a phospholipase A2 (PLA2) inhibitor, AACOCF3, blocks the PAF-induced CBF increase. PGE2 production by oviductal epithelial cells is stimulated by PAF, and WEB-2086, a PAF-receptor blocker, specifically blocks the PAF-induced PGE2 production. Using the fluorescent indicator fura-2, we measured the effect of PAF on intracellular Ca2+ concentration ([Ca2+]i) in individual ciliated cells. PAF induced a transient increase of [Ca2+]i that was blocked by WEB-2086 or by removal of extracellular Ca2+. We propose a mechanism for PAF-mediated signal transduction in the ciliated cells of the oviductal epithelium. Minimal doses of PAF trigger Ca2+ mobilization in tandem with increased PLA2 activity and a COX-2-mediated increase in PGE2. Local PGE2 production by the oviductal mucosa suggests the presence of an autocrine loop controlling ciliary activity.

Animals↗

PubMed2001

Occurrence of polycyclic aromatic hydrocarbons in sewage sludge and their contribution to its toxicity in the toxalert 100 bioassay.

The contribution of polycyclic aromatic hydrocarbons (PAH) present in sewage sludge samples to toxicity was investigated. Chemical analysis using gas chromatography mass spectrometry (GC-MS) and the ToxAlert 100 bioassay, based on the inhibition to Vibrio fischeri, were applied to sludge extracts after purification by column chromatography. The levels of the 16 US EPA PAH analyzed in the sewage sludge samples varied from 17 to 2,030 microg kg(-1). In all samples examined phenanthrene was the most prominent compound. The toxicity data obtained by ToxAlert 100 can be explained by the levels and composition of the different PAH in sewage sludge samples. The present approach can contribute to evaluate the toxicity of sewage sludge.

Environmental Monitoring↗

PubMed2001

New 3-[4-(aryl)piperazin-1-yl]-1-(benzo[b]thiophen-3-yl)propane derivatives with dual action at 5-HT1A serotonin receptors and serotonin transporter as a new class of antidepressants.

A series of new 3-[4-(aryl)piperazin-1-yl]-1-(benzo[b]thiophen-3-yl)propane derivatives were synthesized in an attempt to find a new class of antidepressant drugs with dual activity at 5-HT1A serotonin receptors and serotonin transporter. Title compounds were evaluated for in vitro activity on 5-HT1A receptor and 5-HT transporter. They show high nanomolar affinity for both activities, and in particular, compounds 1-(5-chlorobenzo[b]thiophen-3-yl)-3-[4-(2-methoxyphenyl)piperazin-1-yl]propan-1-ol (7) and 1-(5-fluorobenzo[b]thiophen-3-yl)-3-[4-(2-methoxyphenyl)piperazin-1-yl]propan-1-ol (8) show values (nM) of K(i)=30 and 2.3 for 5-HT1A receptors and K(i)=30 and 12 for serotonin transporters, respectively. In GTPgammaS binding assays, compound 8 revealed antagonist properties to 5-HT1A receptors. Such a pharmacological profile could lead to potent antidepressant agents with new dual mechanism of action.

Animals↗