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ABSTRACT: introduction: The main goal in this study was to know the efficacy of treatment with Secnidazole in schoolchildren acting as asymptomatic carriers of Giardia lumblia and Entamoela histolytica and also to evaluate its toleration. Materials and Methods: A total of 50 children with parasitic disease (from 53 children with Entamoeba histolytica and/or Giardia lamblia) were chosen for the study, with ages ranking from 5 to 14, of either gender, to whom the drug was administered, and coproparasitological control tests were performed to them at third day of therapy. A question form was used to evaluate oral toleration to the drug. Result: From 53 cases studied, the protozoal ratio was as follows: Giardia lamblia 66.03%, followed by Entamoeba histolytica, 33.97 %. Parasitological effectiveness of Secnidazole against Gíardia lamblía was 100%, and against Entamoeba histolytica was 95.45 %. Only one carrier (4.55 %) did not respond to treatment. The drug had a good toleration in 50% of the cases. Most frequent symptoms were hyporexy, headache, abdominal discomfort/pair, dizziness, nausea, vomiting, diarrhea, drowsiness, taste sense anomal1e and itching. Conclusion: Efficacy and a relatively good oral toleration to Secnidazole was demonstrated in this study. Parasite absence was demonstrated after three days of trea1ment. RIESUMEN: Introducción: El propósito de la investigación es conocer la eficacia del Secnidazol en el tratamiento de escolares asintomáticos portadores de Giardia lamblia y/o Entamoeba histolytica, así como el evaluar su tolerancia. Material y métodos: Se escogieron 50 niños parasitados (totalizando 53 casos con Entamoeba histolytica y/o Giardia lamblia), con edades comprendidas entre 5 y 14 años, de uno u otro sexo, a quienes se les administró el medicamento y tres días después se realizaron exámenes coproparasitológicos controles. La tolerancia del medicamento se evaluó mediante encuesta. Resultados: De 53 casos parasitados, la relación de protozoarios fue: Giardia lamblia (66,03%) seguidos de Entamoeba histolylica (33,97%). La efectividad parasitológica del Secnidazol contra Giardia lamblia fue del 100% y de Entamoeba histolytica de 95,45%. Se obtuve un solo caso portador que no respondió al tratamiento (4,55%). El medicamento fue bien tolerado en el 50% de los casos. Los síntomas más frecuentes fueron: hiporexia, cefalea, dolor abdominal, mareos, náuseas, vómitos, diarrea, fatiga, alteración del gusto y prurito. Conclusiones: La eficacia y la relativamente buena tolerancia del Secnidazol fue demostrada en d presente estudie. Se obtuvo cura parasitológica al tercer día de administrado el medicamento.

ABSTRACT: introduction: The objective is to know the prevalence of enteric parasitosis in an urban school in San Francisco parish. Material and methods: 114 children oscillating between 5 and l 5 years of age and of both sexes were chosen among the total school population; coproparasitologics assays were made and epidemiological inquiries were used to obtain data. Results Among the selected children. 74.67% reported positive to one or more enteric parasites; 40.35% were males and 34.21% were females. The 9 to 12 year old group, proved most infected (34.24%), followed by the 5 to 8 year olds (30.69%). Most frequent helminths were: Enterobius vermicularis (45.55%), Trichuris trichiura (27.80%), Ascaris lumbricoides (23.35%) e Hymenolepis nana (3,30%) and protozoa were Blastocystis hominis (37.28%), Giardia lamblia (17.79%), Endolimax nana (16.95%), Entamoeba coli (15.26%). Polyparasitism showed predominance over monoparasitism. Most of the helminthiasis observed were slight cases Poor hygienic habits were evident in the children as well as in the school. Conclusions: An elevated parasitic prevalence was evident at the population submitted to study. RESUMEN: Introducción: El propósito de la investigación es conocer la prevalencia de las enteroparasitosis en una escuda urbana de la parroquia San Francisco. Material y métodos: Del total de la población escolar, se escogieron 114 niños, de edades comprendidas entre 5 y 15 años, de ambos sexos, donde se les realizó exámenes coproparasitológicos y recolección de información a través de encuestas epidemiológicas. Resultados: De los niños seleccionados, 74,55% reportaron positividad para uno o más enteroparásitos. 40,35% fueron masculinos y 34,21% femeninos. Las edades más parasitadas fueron las comprendidas entre 9 y 12 años (34,24%) seguidas de 5 a 8 años 30,69%. Los helmintos más frecuentes fueron: Enterobius vermicularis (45,55%), Trichuris trichiura (27,80%), Ascaris lumbricoides (23,35%) e Hymenolepis nana (3,30%) y lOS protozoos fueron: Blastocystis hominis (37,28%), Giardia lamblia (17,79%), Endolimax nana (16,95%), Entamoeba coli (15,26%). El poliparasilismo predominó sobre el monoparasitismo. Las helmintiasis observadas presentaron en su mayoría una infestación leve. Se evidencia acentuados malos hábitos higiénicos en los niños, así como en la escuela. Conclusiones: Se obtuvo una elevada prevalencia parasitaria en la población estudiada. La Enterobiasis fue la helmintiasis más común.

Fernando Mérida, 1 Carlos Rinaldi, 2, 3 Eduardo J Juan, 4 Madeline Torres-Lugo 1 1Department of Chemical Engineering, University of Puerto Rico-Mayagüez, Mayagüez, Puerto Rico; 2Department of Chemical Engineering, University of Florida, Gainesville, FL, USA; 3J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA; 4Department of Electrical and Computer Engineering, University of Puerto Rico-Mayagüez, Mayagüez, Puerto RicoCorrespondence: Madeline Torres-Lugo Road 108 Km. 1.0 Bo. Miradero. P.O. Box 9046, Mayagüez 00681-9046, Puerto RicoTel +1787 832 4040 Ext. 2585Email madeline@ece.uprm.eduBackground: Magnetic Fluid Hyperthermia (MFH) is a promising adjuvant for chemotherapy, potentiating the action of anticancer agents. However, drug delivery to cancer cells must be optimized to improve the overall therapeutic effect of drug/MFH combination treatments.Purpose: The aim of this work was to demonstrate the potentiation of 2-phenylethynesulfonamide (PES) at various combination treatments with MFH, using low-intensity ultrasound as an intracellular delivery enhancer.Methods: The effect of ultrasound (US), MFH, and PES was first evaluated individually and then as combination treatments. Definity® microbubbles and polyethylene glycol (PEG)-coated iron oxide nanoparticles were used to induce cell sonoporation and MFH, respectively. Assessment of cell membrane permeabilization was evaluated via fluorescence microscopy, iron uptake by cells was quantified by UV-Vis spectroscopy, and cell viability was determined using automatic cell counting.Results: Notable reductions in cancer cell viability were observed when ultrasound was incorporated. For example, the treatment US+PES reduced cell viability by 37% compared to the non-toxic effect of the drug. Similarly, the treatment US+MFH using mild hyperthermia (41°C), reduced cell viability by an additional 18% when compared to the effect of MH alone. Significant improvements were observed for the combination of US+PES+MFH with cell viability reduced by an additional 26% compared to the PES+MFH group. The improved cytotoxicity was attributed to enhanced drug/nanoparticle intracellular delivery, with iron uptake values nearly twice those achieved without ultrasound. Various treatment schedules were examined, and all of them showed substantial cell death, indicating that the time elapsed between sonoporation and magnetic field exposure was not significant.Conclusion: Superior cancer cell-killing patterns took place when ultrasound was incorporated thus demonstrating the in vitro ultrasonic potentiation of PES and mild MFH. This work demonstrated that ultrasound is a promising non-invasive enhancer of PES/MFH combination treatments, aiming to establish a sono-thermo-chemotherapy in the treatment of ovarian cancer.Keywords: MFH, ultrasound, sonoporation, microbubble, PES, membrane permeabilization, enhanced cytotoxicity

Tourettes syndrome (TS) is a developmental disorder that has one of the highest familial recurrence rates among neuropsychiatric diseases with complex inheritance. However, the identification of definitive TS susceptibility genes remains elusive. Here, we report the first genome-wide association study (GWAS) of TS in 1285 cases and 4964 ancestry-matched controls of European ancestry, including two European-derived population isolates, Ashkenazi Jews from North America and Israel and French Canadians from Quebec, Canada. In a primary meta-analysis of GWAS data from these European ancestry samples, no markers achieved a genome-wide threshold of significance (P

Tourette's syndrome (TS) is a developmental disorder that has one of the highest familial recurrence rates among neuropsychiatric diseases with complex inheritance. However, the identification of definitive TS susceptibility genes remains elusive. Here, we report the first genome-wide association study (GWAS) of TS in 1285 cases and 4964 ancestry-matched controls of European ancestry, including two European-derived population isolates, Ashkenazi Jews from North America and Israel and French Canadians from Quebec, Canada. In a primary meta-analysis of GWAS data from these European ancestry samples, no markers achieved a genome-wide threshold of significance (P

Merlis P Alvarez-Berríos,1 Amalchi Castillo,1 Carlos Rinaldi,1–3 Madeline Torres-Lugo1 1Department of Chemical Engineering, University of Puerto Rico, Mayagüez, Puerto Rico; 2J Crayton Pruitt Family Department of Biomedical Engineering, 3Department of Chemical Engineering, University of Florida, Gainesville, FL, USA Abstract: The proteasome inhibitor bortezomib (BZ) has shown promising results in some types of cancer, but in others it has had minimal activity. Recent studies have reported enhanced efficacy of BZ when combined with hyperthermia. However, the use of magnetic nanoparticles to induce hyperthermia in combination with BZ has not been reported. This novel hyperthermia modality has shown better potentiation of chemotherapeutics over other types of hyperthermia. We hypothesized that inducing hyperthermia via magnetic nanoparticles (MFH) would enhance the cytotoxicity of BZ in BZ-sensitive and BZ-resistant cancer cells more effectively than hyperthermia using a hot water bath (HWH). Studies were conducted using BZ in combination with MFH in two BZ-sensitive cell lines (MDA-MB-468, Caco-2), and one BZ-resistant cell line (A2780) at two different conditions, ie, 43°C for 30 minutes and 45°C for 30 minutes. These experiments were compared with combined application of HWH and BZ. The results indicate enhanced potentiation between hyperthermic treatment and BZ. MFH combined with BZ induced cytotoxicity in sensitive and resistant cell lines to a greater extent than HWH under the same treatment conditions. The observation that MFH sensitizes BZ-resistant cell lines makes this approach a potentially effective anticancer therapy platform. Keywords: magnetic fluid hyperthermia, hot water hyperthermia, BZ, enhanced cytotoxicity, thermal sensitization

Merlis P Alvarez-Berríos, Amalchi Castillo, Janet Mendéz, Orlando Soto, Carlos Rinaldi, Madeline Torres-LugoDepartment of Chemical Engineering, University of Puerto Rico, Mayagüez, Puerto RicoAbstract: Magnetic fluid hyperthermia as a cancer treatment method is an attractive alternative to other forms of hyperthermia. It is based on the heat released by magnetic nanoparticles subjected to an alternating magnetic field. Recent studies have shown that magnetic fluid hyperthermia-treated cells respond significantly better to chemotherapeutic treatment compared with cells treated with hot water hyperthermia under the same temperature conditions. We hypothesized that this synergistic effect is due to an additional stress on the cellular membrane, independent of the thermal heat dose effect that is induced by nanoparticles exposed to an alternating magnetic field. This would result in an increase in Cis-diammine-dichloroplatinum (II) (cDDP, cisplatin) uptake via passive transport. To test this hypothesis, we exposed cDDP-treated cells to extracellular copper in order to hinder the human cell copper transporter (hCTR1)-mediated active transport of cDDP. This, in turn, can increase the passive transport of the drug through the cell membrane. Our results did not show statistically significant differences in surviving fractions for cells treated concomitantly with magnetic fluid hyperthermia and cDDP, in the presence or absence of copper. Nonetheless, significant copper-dependent variations in cell survival were observed for samples treated with combined cDDP and hot water hyperthermia. These results correlated with platinum uptake studies, which showed that cells treated with magnetic fluid hyperthermia had higher platinum uptake than cells treated with hot water hyperthermia. Changes in membrane fluidity were tested through fluorescence anisotropy measurements using trimethylamine-diphenylhexatriene. Additional uptake studies were conducted with acridine orange and measured by flow cytometry. These studies indicated that magnetic fluid hyperthermia significantly increases cell membrane fluidity relative to hot water hyperthermia and untreated cells, and hence this could be a factor contributing to the increase of cDDP uptake in magnetic fluid hyperthermia-treated cells. Overall, our data provide convincing evidence that cell membrane permeability induced by magnetic fluid hyperthermia is significantly greater than that induced by hot water hyperthermia under similar temperature conditions, and is at least one of the mechanisms responsible for potentiation of cDDP by magnetic fluid hyperthermia in Caco-2 cells.Keywords: magnetic nanoparticles, synergistic effect, hot water hyperthermia, surviving fraction, viability ratio

Aggregate stability (EA) is the best soil physical health indicator. However, its determination is complex and time-consuming, which discourages its frequent use. Other proposed indicators are either the mean weighted diameter change between capillary wetting (MC) and aggressive wetting (MV) (ΔDMPMC-MV), which requires six water sieving, or the normalized stability index (IEN), which also requires a correction by sand size. This study aimed to evaluate simpler and quicker soil parameters as EA indicators. Soil samples were taken at 0-20 cm from Entisols with sandy loam surface texture of San Luis Province (Argentina) under four soil uses. The IEN, the ΔDMPMC-MV, aggregate mean weight diameter after MV (DMPMV, three sievings), the change of macroaggregate (2000-8000 µm, MA) mass between MC and MV (ΔmasaMAMC-MV, two sievings), and the MA mass after MV (masaMAMV, one sieving) were determined. The IEN was not able to differentiate the four soil uses assessed. The ΔDMPMC-MV was closely related to ΔmasaMAMC-MV (R2=0,99), allowing to reduce the number of water sievings from six to two. However, neither ΔDMPMC-MV nor ΔmasaMAMC-MV significantly reflected the effect of soil use, since they presented a high variability and negative values that hinder their interpretation. The DMPMV is a good indicator of EA and its use would allow to reduce the number of water sievings to three. However, DMPMV was very closely related to masaMAMV (R2=0,99). Thus, EA could be determined through the stability of MA measured through masaMAMV, which requires only one water sieving. This would encourage soil physical health monitoring. Nevertheless, it is necessary to continue the research considering a greater range of edaphoclimatic conditions. [ABSTRACT FROM AUTHOR]

In this study, we assessed the notable preservation of mercury‐enriched ancient dental remains. The studied specimen belonged to a 30‐year‐old woman, and it was collected from Temple XIII at the archaeological site of Palenque, Mexico (17°29'2.32"N, 92°2'46.78"W; a UNESCO World Heritage Site). The preservation of an ancient molar was studied by high‐resolution scanning electron microscopy and energy‐dispersive X‐ray spectroscopy (HRSEM–EDS), and the obtained results were compared to those recorded for contemporary tooth specimens. Measured and conventional carbon ages for the ancient molar were 1000 ± 30 and 1260 ± 30 bp, respectively. Energy‐dispersive spectroscopy (EDS) analysis showed that the accumulated Hg in the ancient molar was 66% (by weight). In contrast, the Hg content in the contemporary molar was observed to be below the analytical detection limits. Clearly, Hg accumulated preferentially in ancient dental structures. Aging favoured the overall exchange of Hg for structural Ca; namely, chemical migration from one dental compartment to the other, mineral transformations, enamel hypoplasia, and the accumulation of Hg and Al in bio‐organic structures. Overall, we observed excellent preservation of biogenic material with varying physiological function(s), including abundant odontoblasts (tubules and spheres), dentinal tubules and nervous system fibrils. [ABSTRACT FROM AUTHOR]

Flocculants are widely investigated chemicals, which can be utilized to remedy or purify waste water from industries including petroleum, fabric, mining. Although many types of flocculants have been explored, each flocculant has it's merits and demerits. Thus, we investigated poly (N,N-diallyl-N,Ndimethylammonium chloride) cationic flocculants. This work reports a novel flocculant which was developed based on the widely used flocculant, poly (N,N-diallyl-N,N-dimethylammonium chloride) (DADMAC) cationic polymers. This newly developed flocculant has not only enhanced flocculant performance, but also provided reusability of this polymer with insertion of crosslinking groups. The new developed copolymer, Poly (DADMAC-co- VEMEA), was synthesized via random radical polymerization approach and characterized by NMR and FTIR. The flocculation performance for these polymers were evaluated and studied by turbidity experiments and zeta-potential measurements. Their flocculation performance over poly (DADMAC) homopolymer can be improved by adding a VEMEA unit to the polymer chain and partially crosslinking the copolymer. This newly developed flocculant can provide new direction in developing flocculants potentially. [ABSTRACT FROM AUTHOR]

Background Recurrent abdominal pain is a common and costly health-care problem attributed, in part, to visceral hypersensitivity. Increasing evidence suggests that gut bacteria contribute to abdominal pain perception by modulating the microbiome-gut-brain axis. However, specific microbial signals remain poorly defined. γ-aminobutyric acid ( GABA) is a principal inhibitory neurotransmitter and a key regulator of abdominal and central pain perception from peripheral afferent neurons. Although gut bacteria are reported to produce GABA, it is not known whether the microbial-derived neurotransmitter modulates abdominal pain. Methods To investigate the potential analgesic effects of microbial GABA, we performed daily oral administration of a specific Bifidobacterium strain ( B. dentium ATCC 27678) in a rat fecal retention model of visceral hypersensitivity, and subsequently evaluated pain responses. Key Results We demonstrate that commensal Bifidobacterium dentium produces GABA via enzymatic decarboxylation of glutamate by GadB. Daily oral administration of this specific Bifidobacterium (but not a gadB deficient) strain modulated sensory neuron activity in a rat fecal retention model of visceral hypersensitivity. Conclusions & Inferences The functional significance of microbial-derived GABA was demonstrated by gadB-dependent desensitization of colonic afferents in a murine model of visceral hypersensitivity. Visceral pain modulation represents another potential health benefit attributed to bifidobacteria and other GABA-producing species of the intestinal microbiome. Targeting GABAergic signals along this microbiome-gut-brain axis represents a new approach for the treatment of abdominal pain. [ABSTRACT FROM AUTHOR]

INTRODUCTION: described by Robert Koch in 1882, Mycobacterium tuberculosis is a gram-positive, acid-alcohol resistant, strictly aerobic, immobile, non-encapsulated, non-spore forming bacillus. The growth of Koch's bacillus is slow (2-6 weeks), requiring specific media (Low-enstein Jensen); the Ziehl-Neelsen stain gives it a reddish coloration. Tuberculous compromise of the central nervous system is acquired by hematogenous transmission, with host response and the virulence factor of the bacteria is of crucial importance in determining whether the infection is contained or develops and to what degree it will spread. The location of "Rich foci" and the host's ability to control them will determine the form of tuberculosis that develops; the majority evolve into meningitis, and less commonly into encephalitis, intracranial tuberculoma, or abscess. OBJECTIVE: describe the image range of tuberculous compromise in the central nervous system to be considered as differential diagnosis in patients at Hospital General de Mexico Dr. Eduardo Liceaga. MATERIAL AND METHODS: a retrospective, descriptive study of patients with diagnosis of tuberculosis in the central nervous system. The study includes a review of computed tomography and magnetic resonance studies, as well as histopathological results of autopsies and biopsies with diagnosis of tuberculoma, tuberculous leptomeningitis, and granulomatous meningovasculitis performed at Hospital General de Mexico Dr. Eduardo Liceaga in the period between March 2009 and March 2016. CONCLUSIONS: because tuberculosis is the great simulator, it is important that healthcare personnel be made aware of the image expressions each patient may present, especially if the patient has risk factors or lives in a developing country. [ABSTRACT FROM AUTHOR]

BACKGROUND: image diagnosis methods have changed the way we approach the different pathologies which affect the sellar region; magnetic resonance and computed tomography are the methods of choice for evaluation. OBJECTIVE: identify differential diagnoses of lesions of the sellar region, which resemble macroadenoma, and their different characteristics, by image studies. MATERIAL AND METHODS: a retrospective and descriptive studio; we examined 117 patients with diagnosis of lesion of the sellar region in the period from March 2011 to March 2016 in a magnetic resonance service, and analyzed the different characteristics by image studies and their correlation with histopathological diagnoses. RESULTS: female patients were most commonly affected by lesions of the sellar region, at a rate of around 64%; concordance between radiological and histopathological diagnoses was found in 61.2% of cases; the most common diagnoses to consider in our population are: craniopharyngioma, meningioma, chordoma, and germinoma, taking into consideration rarer differential diagnoses such as tuberculoma, histiocytosis, macroadenoma with lymphocytic hypophysitis, and cystic lesions. CONCLUSIONS: knowing the different differential diagnoses, and characteristics by image studies, of lesions of the sellar region will help improve diagnosis, treatment, and prognosis and reduce potential complications. Magnetic resonance is the procedure of choice to evaluate localized lesions in that region. [ABSTRACT FROM AUTHOR]

A 342-day trial was conducted comparing productive performance in a synthetic strain of red tilapia Pargo-UNAM (PU) and in a Nile tilapia Oreochromis niloticus (NT) population during four experimental stages: Is, IIs, IIIs and IVs. In the Is, 900 nonsexually inverted PU and NT fry (0.07 and 0.06 g respectively) were each placed in four plastic tanks per strain. For the IIs [1.59 g (PU) and 1.39 g (NT)], the population in each replicate was reduced to 440. For the IIIs [36.6 g (PU) and 36.5 g (NT)], the tanks were culled to 220 fish and transferred to 1 m3 cages. At the end of IIIs, all the fish were sexed and 40 fish (133.3-231.6 g) of a single sex were placed in a cage, with eight per genetic group. Survival was similar between groups in any stage. Weight gain was similar in Is and IIs, while PU exhibited more growth than NT during the IIIs. At the end of the IVs, weight of males was similar (PU=623.4 g; NT=650.1 g), but PU females had higher weight (435.4 g) than NT females (323.6 g). Fillet rate (>32%) was similar in all groups. Advantages of culturing the synthetic strain 'PU' are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Objective: To investigate the bioecological relationship between Chagas disease peridomestic vectors and reptiles as source of feeding. Methods: In a three-story building, triatomines were captured by direct search and electric vacuum cleaner search in and outside the building. Then, age structure of the captured Triatoma maculata (T. maculata) were identified and recorded. Reptiles living in sympatric with the triatomines were also searched. Results: T. maculata were found living sympatric with geckos (Thecadactylus rapicauda) and they bit residents of the apartment building in study. A total of 1 448 individuals of T. maculata were captured within three days, of which 74.2% (1 074 eggs) were eggs, 21.5% were nymphs at different stages, and 4.3% were adults. Conclusions: The association of T. maculata and T. rapicauda is an effective strategy of colonizing dwellings located in the vicinity of the habitat where both species are present; and therefore, could have implications of high importance in the intradomiciliary transmission of Chagas disease. [Copyright &y& Elsevier]

Damage evolution in a wrought magnesium alloy under uniaxial tensile deformation is investigated. Sectioned specimens subjected to interrupted tensile deformation were examined under optical microscopy to quantify the number density of cracked intermetallic particles as a function of applied strain. Digital image analysis of the optical images was employed to quantify damage by separating cracked from non-cracked particles. Finally, an internal state variable damage model was shown to adequately capture the experimentally observed damage progression due to the intermetallics. [ABSTRACT FROM AUTHOR]

Copyright of Vida y Ética is the property of Pontificia Universidad Catolica Argentina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Vida y Ética is the property of Pontificia Universidad Catolica Argentina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Context: Environmental exposure to particulate matter of 2.5 microm or less (PM[2.5]) has been associated with changes in heart rate variability (HRV).Objective: To evaluate the effect of supplementation with omega-3 polyunsaturated fatty acids on the reduction of HRV associated with PM[2.5] exposure.Design: Randomized double-blind trial.Setting: Mexico City, Mexico.Participants: 50 nursing home residents older than 60 yr.Intervention: Randomization to either 2 g/d of fish oil versus 2 g/d of soy oil as the control, with 6 mo follow-up (1-mo presupplementation and 5-mo supplementation) or repeated HRV measurements. PM[2.5] was monitored indoors and outdoors.Main Outcome Measure: The association between HRV and 1 SD change in PM[2.5] (8 microg/m[3]).Results: In the group receiving fish oil, the reduction in HRV-high-frequency log[10]-transformed associated with a 1-SD change in PM[2.5] was-54% (95% confidence interval,-72,-24) in the presupplementation phase, and only-7% (95% confidence interval,-20,+7) in the supplementation phase (p < 0.01 for the effect of supplementation), with changes in other HRV parameters also being significantly less pronounced during supplementation. Small decreases in PM[2.5]-associated reductions in HRV parameters also occurred in the group receiving soy oil, but these were not significant. Fish oil supplementation was significantly better in preventing the reduction in percentage of successive normal RR intervals differing by more than 50 ms (p = 0.03) and the root square of the mean of the sum of the squares of differences between adjacent intervals (p = 0.05) than soy oil supplementation.Interpretation: Supplementation with 2 g/d of fish oil prevented HRV decline related to PM[2.5] exposure in the study population. [ABSTRACT FROM AUTHOR]