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Biomedical subjects

J Rivera

Publications and source records attributed to J Rivera.

At least 19 recordsLinked to original sources
PubMed2006

Dioxin emissions from thermal waste management in Medellín, Colombia: present regulation status and preliminary results.

Preliminary results of a study undertaken to characterize dioxin and furan releases from waste incineration plants operating in Medellín-Colombia are presented. Emission and fly ash samples were collected from representative plants burning medical and industrial residues to characterize PCDD/PCDF levels. Analyses were carried out following European standards for stationary gas emissions EN-1948:1996 and US EPA 1613 (fly ashes). Final extracts were analyzed by both high resolution gas chromatography coupled to high resolution mass spectrometry (HRGC-HRMS) and high resolution gas chromatography coupled to ion trap tandem mass spectrometry (HRGC-ITMS/MS). Preliminary results revealed emission levels of 1-30.3 ng I-TEQ/Nm3 depending on whether or not an air pollution control system (APCS) was installed. Fly ashes contained 8.5-68 ng I-TEQ/g. Critical issues that should be addressed in an assessment and in developing waste management plans in Colombia are discussed.

Carbon↗
PubMed2006

Organochlorine compounds (PCBs, PCDDs and PCDFs) in seafish and seafood from the Spanish Atlantic Southwest Coast.

Concentrations and congener specific profiles of PCDD/Fs and PCBs were determined in edible fish and seafood species from the Coast of Huelva, in the Spanish southwest Atlantic coast. Five fish species, namely wegde sole (Dicologoglossa cuneata), common sole (Solea vulgaris), white seabream (Diplodus sargus), sardine (Sardina pilchardus), angler fish (Lophius piscatorius), two shellfish species (Donax trunculus and Chamelea gallina), common cuttlefish (Sepia officinalis) and prawns (Parapenaeus longirostris), frequently found and consumed in the area were analysed. Concentrations ranged from 861 to 23787pg/g wet weight for total PCBs, while 2,3,7,8-PCDD/Fs showed concentrations ranging from 0.2 to 1.18pg/g wet weight. WHO-TEQ concentrations ranged from 0.038 to 0.186pg WHO-TEQ(PCDD/Fs)/g wet weight, values well below the maximum concentrations established by the EU. When non- and mono-ortho PCBs were included the values increased to a maximum of 0.99pg WHO-TEQ(PCDD/Fs+PCBs)/g wet weight. The PCB and PCDD/F accumulation pattern found in the samples analysed showed a distribution typically reported for marine samples, and no remarkable differences were found between species. The PCBs were the ones contributing with the highest percentage to the total TEQ content in most species studied. Concerning the seafood, specially prawns and shellfish, the opposite was observed and PCDD/Fs were found to contribute with a higher percentage than PCBs. The congener specific contribution to the TEQ showed PCB 126 followed by 1,2,3,7,8-PeCDD and 2,3,4,7,8-PeCDF as the most abundant ones.

Animals↗
PubMed2006

The synovial sarcoma translocation protein SYT-SSX2 recruits beta-catenin to the nucleus and associates with it in an active complex.

Localization of beta-catenin in the cell is a key determinant in its decision to function as a critical mediator of cell adhesion at the surface or a transcription activator in the nucleus. SYT-SSX2 is the fusion product of the chromosomal translocation, t(X;18)(p11.2;q11.2), which occurs in synovial sarcoma, a soft tissue tumor. SYT-SSX2 is known to associate with chromatin remodeling complexes and is proposed to be involved in controlling gene expression. We report that SYT-SSX2 plays a direct role in beta-catenin regulation. When expressed in mammalian cells, SYT-SSX2-induced beta-catenin recruitment to the nucleus. Interestingly, known target genes of canonical Wnt were not activated as a result of SYT-SSX2 expression, nor was the nuclear localization of beta-catenin due to one of the signaling pathways normally implicated in this event. beta-Catenin accumulation in the nucleus led to the formation of a transcriptionally active nuclear complex that contained SYT-SSX2 and beta-catenin. More importantly, depletion of SYT-SSX2 in primary synovial sarcoma cells resulted in loss of nuclear beta-catenin signal and a significant decrease in its signaling activity. These results unravel a novel pathway in the control of beta-catenin cellular transport and strongly suggest that SYT-SSX2 contributes to tumor development, in part through beta-catenin signaling.

Active Transport, Cell Nucleus↗
PubMed2006

[Effects of NSAID on blood pressure among hypertensive patients with a high cardiovascular risk].

BACKGROUND: An elevation in the risk of cardiovascular (CV) events and blood pressure (BP) levels in patients treated with COX-2 inhibitors compared to non selective NSAID has been shown previously. OBJECTIVES: To compare the effects of NSAID (COX-2 inhibitors and non-selective) on BP levels and control of HT. To determine the association between NSAID use and coronary heart disease in HT patients with elevated CV risk. METHODS: Cross sectional epidemiological study in 8126 ambulatory HT patients, older than 40, with a high CV risk. We obtained data on personal variables, CV risk factors, previous CV history, CV medication, analgesic and anti inflammatory drugs (AID). Control of HT was classified: optimal, suboptimal and no control. Absolute CV risk was calculated according to the WHO-ISH score. RESULTS: 44.2% of subjects took ASA and 3.7% another NSAID. SBP was 5.90 mmHg (95%CI: 2.53-9.27 mmHg) higher (p < 0.05) in patients treated with NSAID than in those with no AID medication. Patients having ASA, both SBP and DBP were 5.89 mmHg (p < 0.01) and 2.25 mm Hg (p < 0.05) respectively, lower than in patients with NSAID. However, mean SBP was similar in the ibuprofen group compared to without AID; 11.12 mmHg lower (95%CI: 3.66-18.58) than in the group on NSAID (p < 0.05) and 8.82 mmHg (95%CI: 0.27-17.38) (p < 0.05) lower than in those on COX-2 inhibitors. CONCLUSIONS: Among HT patients, NSAID therapy (selective or not) is associated with a higher level of SBP than in those without such medication. However, patients treated exclusively with Ibuprofen show similar levels of SBP than without NSAID treatment. Frequency of ischemic disease was significantly higher in the group treated with COX-2 inhibitors than in the non-selective NSAID treated group or in patients without NSAID treatment.

Aged↗
PubMed2005

Levels and trends of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (PCBs) in Spanish commercial fish and shellfish products, 1995-2003.

The polychlorinated dibenzo-p-dioxin (PCDD), dibenzofuran (PCDF), and polychlorinated biphenyl (PCB) contents of 123 Spanish commercial salmon, tuna fish, sardine, oyster, mussel, and clam samples from 1995 to 2003 were investigated. A significant decrease of dioxin and non-ortho PCB concentrations in the studied species was found over the years. The decrease was greater in the case of dioxins than in that of non-ortho PCBs, especially during the early years of the study. PCB and PCDD/F concentrations in the years 2001-2003 were comparable to those reported in the literature for similar species collected after 1999. Mean PCB concentrations ranged from 3.46 ng/g of fresh weight (fw) in clams to 100 ng/g of fw in tuna fish. PCDD/F mean current levels ranged from 0.62 pg/g of fw in clams to 2.89 pg/g of fw in oysters. Toxic equivalent quantities (WHO-TEQ) ranged from 0.05 pg of WHO-TEQ(PCDD/Fs)/g of fw in clams to 0.5 pg of WHO-TEQ(PCDD/Fs)/g of fw in salmon (in the upper bound determination levels). When coplanar PCBs were included, the WHO-TEQ(PCDD/Fs+cop) (PCBs) values increased by a range of 1.7 times in oysters to 14.1 times in tuna fish. The decrease in dioxin concentrations suggests that efforts to control dioxin emissions and to reduce human exposure through foodstuffs are succeeding. The high contribution of PCBs to total WHO-TEQs in the fish and shellfish species investigated suggests that it is important to determine PCBs in foodstuffs, and especially in fish products, and they should be included in further research and future legislation.

Animals↗
PubMed2005

Polychlorinated dibenzo-p-dioxins, dibenzofurans and 'dioxin-like' PCBs in flue gas emissions from municipal waste management plants.

The aim of this work is to give representative data on polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyl (PCBs) from stack gas emissions of an urban solid waste management plant which has to comply with the limit of 0.1 ng I-TEQ/Nm3. In particular, the study is focused on 29 target compounds, the seventeen 2,3,7,8-PCDDs/Fs, four non-ortho PCBs and eight mono-ortho PCBs which configure so-called 'dioxin-like' PCBs (DL-PCBs). To this end, emission measurements were performed during one year over the three operating combustion lines in a selected waste management plant. In general, accurate methodology allowed characterizing all target compounds in almost all the samples analyzed. In addition, a typical pattern for DL-PCBs is reported. The pattern presented PCB #118 to be the highest, nevertheless the figures demonstrated DL-PCBs contribution to the total TEQ around 3% being PCB #126 the most important congener due to its TEF of 0.1. Finally, remarkable differences were achieved in comparison with both environmental and biological samples such as soils, sediments, human milk or fish since these matrices may present DL-PCB contribution to the total TEQ up to 77%.

Air Pollutants↗
PubMed2005

Organochlorine compounds in liver and concentrations of vitellogenin and 17beta-estradiol in plasma of sea bass fed with a commercial or with a natural diet.

Results from previous experiments directed to determine the effect of different nutritional factors or the effect of xenobiotics on hormonal control of reproduction, lead to the hypothesis that hormonal perturbations repeatedly observed in sea bass (Dicentrarchus labrax) broodstock feeding commercial diets could have been caused by the presence of aryl hydrocarbon receptor (AhR) ligands, such as dioxins, furans and polychlorinated biphenyls (PCBs) in the diet. To evaluate this hypothesis, dioxins and related compounds were analysed in liver of female sea bass fed with a commercial or with a natural diet consisting of trash fish (bogue, Boops boops), and concentrations of vitellogenin (VTG) and 17beta-estradiol (E2) were determined in plasma obtained previously in monthly samplings of these animals. As observed in other experiments, females fed with a commercial diet exhibited lower VTG and higher E2 plasma levels than females fed with the natural diet. In liver, sea bass fed with the commercial diet exhibited a profile clearly dominated by high-chlorinated dioxins while in fish fed with the natural diet this profile was dominated by low chlorinated furans. However, typical AhR ligands, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin showed no differences between groups or, as is the case of planar PCBs, showed higher concentrations in the liver of fish fed with the natural diet. These results do not permit to explain the observed hormonal alterations by a possible antiestrogenic effect caused by dioxins and related compounds.

Analysis of Variance↗
PubMed2005

Priority organic pollutant assessment of sludges for agricultural purposes.

A comprehensive characterization of five of the seven priority organic pollutants listed in the draft of the "Working document on sludge" [EU, 2000. Working Document on Sludge 3rd Draft. Unpublished, 19 p] has been carried out during 2001-2003 in sludge samples from Catalonia (NE Spain). One hundred and thirty-nine samples belonging to 20 Waste Water Treatment Plants (WWTPs), seven sludge treatment (thermal drying) and three composting sludge plants were taken in order to determine the concentration of polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs), di-2-(ethyl-hexyl)-phthalate (DEHP), nonylphenol and nonylphenol ethoxylates with one or two ethoxy groups (NPE), polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). PCDD/F concentrations were in general lower than the 100 ng I-TEQ/kg limit suggested in the above-mentioned document. In the same way, 98.5% for PCBs, 97% for PAH and 92.8% for DEHP of the samples presented concentrations lower than 0.8 mg/kg dm, 6 mg/kg dm and 100 mg/kg dm, respectively. In contrast, the vast majority of samples contained NPE concentrations much higher than 50mg/kg dm limit. The values ranged from 14.3 to 3150 mg/kg dm (median value=286.6 mg/kg) being composted sludge samples the less contaminated ones (17.9-363.4 mg/kg dm; median value=89.3 mg/kg). Special attention should be paid to the Catalan sludge NPE contamination owing to the high levels detected.

Agriculture↗
PubMed2005

Flavonoids inhibit platelet function through binding to the thromboxane A2 receptor.

BACKGROUND: Dietary flavonoids are known for their antiplatelet activity resulting in cardiovascular protection, although the specific mechanisms by which this inhibition occurs has not been fully established. OBJECTIVE: The aim of this study was to investigate the interaction of nine flavonoids representative of various chemical classes, with platelet responses dependent on thromboxane A(2) (TxA(2)) generation and on receptor antagonism, and to analyze the structural requirements for such effects. METHODS: The effect of several types of flavonoids on platelet aggregation, serotonin release, and TxA(2) generation was investigated. Competitive radioligand binding assays were used to screen for affinity of these compounds to TxA(2) receptors. RESULTS: Flavones (apigenin and luteolin) and isoflavones (genistein) abrogated arachidonic acid and collagen-induced platelet responses, such as aggregation and secretion, with a less substantial effect on TxA(2) synthesis. These compounds were identified as specific ligands of the TxA(2) receptor in the micromol L(-1) range, this effect accounting for antiplatelet effects related to stimulation with those agonists. Tight binding of flavonoids to the human TxA(2) receptor relies on structural features such as the presence of the double bond in C2-C3, and a keto group in C4. CONCLUSIONS: The inhibition by specific flavonoids of in vitro platelet responses induced by collagen or arachidonic acid seems to be related, to a great extent, to their ability to compete for binding to the TxA(2) receptor. Therefore, antagonism of this TxA(2) receptor may represent an additional mechanism for the inhibitory effect of these compounds in platelet function.

Apigenin↗
PubMed2005

[Retained intraocular foreign body. an unusual presentation].

CLINICAL CASE: A 25-year-old man presented with a unilateral retinal detachment, and an ipsilateral preretinal mass; ultrasonographic findings included a high-reflective peripheral mass and a retinal fold. A presumptive diagnosis of a peripheral toxocara granuloma was entertained. We performed a 360 degree circumferential scleral buckle and a conventional vitrectomy via the pars plana. Histologic examination of the mass defined a central non-metallic foreign body surrounded by fibrous tissue. DISCUSSION: An intraocular non-metallic foreign body, surrounded by a fibrous capsule and feeding and draining blood vessels, can mimic the characteristics of a peripheral toxocara granuloma, and the differential diagnosis has to be kept in mind.

Adult↗
PubMed2004

Temporal trends of PCDDs/PCDFs in ambient air in Catalonia (Spain).

This paper reports the results of an assessment of dioxin levels in ambient air in samples collected in the four provinces of Catalonia (Spain) performed by the Environment Department of the Autonomous Government of Catalonia and the Spanish Council for Scientific Research (CSIC). The study includes compiled data of more than 133 samples collected in 28 different sites (rural, urban, suburban and industrial) between 1994 and 2002. The levels revealed a variable content of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDDs/PCDFs) depending both on the area and the contamination source. Thus, concentrations from 16 to 954 fg I-TEQ/Nm(3), with a mean value of 180 fg I-TEQ/Nm(3), were determined in industrial areas. The levels found in urban and suburban sites varied from 10 to 357 fg I-TEQ/Nm(3), with a mean value of 80 fg I-TEQ/Nm(3). The lowest concentrations were found in rural areas, ranging from 5 to 125 fg I-TEQ/Nm(3), with a mean value of 42 fg I-TEQ/Nm(3). As part of the project, levels of samples collected in parallel using two different samplers, a total suspended particulate (TSP) sampler and PM10 sampler, were compared. The results of 11 different campaigns indicated that both methods are comparable and no significant differences were determined.

Journal Article↗
PubMed2004

First assessment of dioxin emissions from coal-fired power stations in Spain.

In this work, the findings of the first assessment of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in emissions releases to the atmosphere from coal-fired power plants are given. A total of five plants were selected for the study located at different provinces in Spain. In all the cases, the results revealed very low levels, in the range of 0.41 pg I-TEQ/Nm(3). The profile indicated in the majority of the cases predominance of highly chlorinated congeners being OCDD the most important contributor. The findings were also used to estimate contribution of PCDDs/PCDFs emitted from coal-fired power plants in Spain. Individual plant results revealed values below 0.02 g I-TEQ per year and plant. Nevertheless, considering the total coal consumption in Spain in 1997, the values are comparable to those reported in other countries in the range of 0.6-0.7 g I-TEQ per year. Moreover, emission factors were determined considering operating conditions of evaluated plants. In general, large variability was observed and values below 1-5 pg I-TEQ/kg coal were early reached.

Air Pollutants↗
PubMed2004

Dietary intakes of polychlorinated dibenzo-p-dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls in Spain.

Congener-specific analyses of seventeen 2,3,7,8-substituted PCDD/Fs, three non-ortho and 8 mono-ortho dioxin-like polychlorinated biphenyls (PCBs) were performed on 258 Spanish foodstuff samples, mainly of animal origin, for 2000--03. Daily dietary intakes of PCDD/Fs and PCBs, expressed as toxic equivalents (WHO-TEQs), were estimated by combining food consumption data from the Spanish National Institute Statistics survey and concentration levels measured in individual samples, using upper bound determination values (not detectable = limit of detection). The calculated dietary intake of PCDD/Fs for a person weighing 70 kg was 1.35+/-0.11pg WHO-TEQs kg(-1) bw day(-1), and 3.22+/-0.75 pg WHO-TEQs kg(-1) bw day(-1) if dioxin-like PCBs (non- and mono-ortho PCBs) were included, showing the importance of their inclusion in monitoring studies. Both values were within the range of tolerable daily intake (TDI) proposed by the WHO (1-4pg WHO-TEQs kg(-1) bw day(-1)). The current levels are lower than earlier intakes estimates conducted in Spain. Meat and meat products accounted for more than 35% of the intake, followed by milk and milk products (29%), vegetables oils (19%), fish and seafood (11%) and eggs (4%). Dioxin-like PCBs are an important component in the total WHO-TEQs in foodstuffs. This is particularly true for the fish food group, where the total WHO-TEQs is dominated by dioxin-like PCBs (up to 80% of WHO-TEQs in some cases).

Benzofurans↗
PubMed2004

Genetic variants of the extra-large stimulatory Gs protein alpha-subunit and risk of thrombotic and haemorrhagic disorders.

A polymorphism of the gene encoding the extra-large stimulatory G-protein alpha-subunit (XLalphas), originally identified in three patients with a bleeding tendency, involved a 36-bp insertion and two missense changes. A paternally-inherited insertion displayed a moderate platelet Gsalpha over-expression, which lead to platelet hypo-reactivity. These data prompted us to investigate the genetic, functional and clinical relevance of this polymorphism in the Mediterranean population. We included 414 healthy subjects and three case/control studies: 263 consecutive patients with a first episode of primary intracerebral haemorrhage, 195 patients with deep venous thrombosis, and 104 patients with cerebrovascular disease. Controls were selected by approximating criteria to match selected risk factors to patients. Moreover, we performed studies of platelet function. We developed a simple method to determine the methylated allele, by digestion of genomic DNA with Sma I before polymerase chain reaction amplification. We identified two new rare variants, resulting from the loss of repeat units 7 and 5. The AB genotype was present in 3.6% of healthy population and the prevalence of the B allele was similar among cases and controls. Accordingly, the non-methylated B allele did not modify either the expression of platelet Gsalpha or the platelet response to Gs-agonists. Thus, our study suggests a minor functional role of XLalphas polymorphism in thrombotic or in haemorrhagic disorders.

Aged↗
PubMed2004

Evaluation of refrigerated platelet concentrates supplemented with low doses of second messenger effectors.

With the goal of producing haemostatically effective platelet concentrates (PCs) with a longer shelf-life, we aimed to identify a simple combination of platelet inhibitors, with a low pharmacological load, which could avoid the unacceptable loss of platelets stored under refrigerated conditions. PCs stored with different combinations of second messenger effectors were analysed at days 5, 10 and 15 of storage and compared with those supplemented with ThromboSol--a combination of six platelet inhibitors that protects cells from cold damage. The following parameters were analysed: platelet counts, biochemical parameters (glucose, pH, bicarbonate, lactate), cell lysis (lactic dehydrogenase, LDH), membrane glycoproteins (GPs), platelet aggregation, fibrinogen binding and hypotonic shock response. We characterized the combination of amiloride and sodium nitroprusside (at 1/2 the dose included in ThromboSol). This was found to be similar to ThromboSol and superior to nontreated units in the prevention of cold-induced platelet aggregation at day 15 of storage (maintenance of 78% and 80% of initial platelet counts, respectively), preservation of GPIbalpha (11% and 12% better maintenance of mean fluorescence intensity compared with control units, respectively), and reduced cell lysis (13% and 11% decrease in supernatant LDH, respectively). The reduced pharmacological load with the identified solution compared with ThromboSol is an argument in favour of the potential use of these agents when designing strategies to improve PC storage.

Blood Platelets↗
PubMed2003

Time and space patterns of volatile organic compounds in a sewage treatment plant.

47 regulated and non-regulated volatile organic compounds (VOCs) were characterised by closed-loop stripping analysis (CLSA) and high resolution gas chromatography coupled to mass spectrometry (HRGC/MS) in 28 aqueous samples from 4 sampling points along a sewage treatment plant in Manresa, Catalonia, Spain. A 4 x 2(2) factorial design (16 samples) was first prepared for the sampling, and reinforced with 12 additional samples at the plant influent. The total analyte weighted mean concentration was 232 microg x l(-1) at the plant influent, with a mass flow of 2231 kg x yr(-1). Petroleum solvents and terpenic compounds accounted for 79% of the influent analyte concentration. VOC concentration in influent was clearly higher for most VOCs from 12 to 22 h (high organic load hours), and lower from 24 to 10 h (lower organic load). Differences between time bands were confirmed through t tests. Differences between weekdays and the weekend were not so clear, and could not be confirmed through t tests. VOC concentrations along the plant are discussed. Overall analyte removal in the plant was 89%.

Environmental Monitoring↗
PubMed2003

A comparison of TEQ contributions from PCDDs, PCDFs and dioxin-like PCBs in sewage sludges from Catalonia, Spain.

Eight sewage sludges from rural, urban and industrial wastewater treatment plants (WWTPs) in Catalonia (Spain) were analysed for polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs) to determine the present levels of contamination. A method based on an automated cleanup system followed by an isotope-dilution high-resolution mass spectrometric analysis was employed. Total toxicity equivalent (WHO-TEQ) values were calculated using the toxicity equivalent factors (WHO-TEFs) proposed by WHO for dioxin-like PCBs, PCDDs and PCDFs. The WHO-TEQ(PCDD/F) values for these samples ranged from 4.9 to 20.8 pg/g dry weight (d.w.), with a mean value of 9.3 pg/g d.w., whereas WHO-TEQ(PCB) levels ranged between 1.9 and 6.6 pg/g d.w., with a mean value of 4.2 pg/g d.w. The WHO-TEQ(PCB) contribution varied from 13% to 50%, suggesting that PCB contribution on the toxicity of the samples must be taken into account. Moreover, these contemporary PCDD, PCDF and PCB concentrations were compared with previous data obtained from sewage sludge samples collected during the 80s. Our findings show that contemporary PCDD, PCDF and PCB levels have declined since the 80s.

Automation↗