Concentrations For Longer Periods Research Articles

A new way of Presbyopia Treatment in Young People (20-40) years by Physical Exercises of the Eye Muscles.

Examination of degree of vision for patient to determine presbyopia in young people before and after therapeutic exercises and to know the amount of improvement in each session after taking a history of the patient and identification of treatment methods according the prescription with the eye moving to all directions and push it forward to reduce pressure on the eye muscle about 20 mints during the exercises (1-6) session in order to stimulate the weak eye.
 The appearance of presbyopia among young people from new cases because concentration for long periods and for more than 4 hours using the modern devices, which caused the occurrence phenomenon among young people and need for reading glasses. All patients were treated of and improved in the degree of consideration each session with therapeutic exercises after identifying and moving the weak eye muscle and found the examination and do not need to use any glasses to read during the examination and get visual acuity (VA=6/6 or 6/9).

Toxicopathic effects of waterborne Cd in sole juveniles, a prospective pollution monitoring sentinel for estuarine ecosystems

IntroductionEstuarine ecosystems are under high anthropogenic pressure and receive a wide Q7 variety of contaminants, including metals. They can remain trapped in estuarine sediments at high concentrations for long periods but eventually they can be released to the overlying water and become toxic for the resident benthic biota. As a consequence, biomonitoring programs surveying the health status of estuaries and coastal areas count with benthic species for the assessment of health disturbances in these specific ecosystems. The present investigation aims at recognizing toxicopathic effects elicited in estuarine life stages of the benthic fish Solea senegalensis on exposure to waterborne Cd, a model compound for metal contamination.MethodsBiological responses to metal exposure were assessed based on the application of a “biomarker + histopathology” approach. Two-year old sole juveniles were exposed to various concentrations of waterborne Cd for 3 and 7 days (Control; Low Cd: 1 µg/l; Mid Cd: 10 µg/l and High Cd: 1000 µg/l). Liver samples were collected for chemical analysis at day 7. Biological samples were collected at days 3 and 7 for biochemical (brain and liver), histochemical (liver) and histopathological analysis (liver, gills and gonad).ResultsBrain acetyl cholinesterase was inhibited after 7 days exposure, indicating neurotoxic effects on exposure to 1000 µg Cd/l. Hepatic catalase and glutathione-Stransferase were induced at day 3 and inhibited at day 7, which suggests a bell-shaped response. A dose-dependent lysosomal membrane destabilization in hepatocytes was recorded at day 7. In parallel, histopathological lesions in gills, liver and gonad were more frequent at day 7 in soles exposed to high Cd concentrations.DiscussionOverall, the “biomarker + histopathology” approach revealed that waterborne Cd causes toxicopathic effects in sole juveniles upon exposure to environmentally relevant concentrations (10 µg Cd/l). The effects were clearly time dependent, and thus it is conceivable that more severe biological effects would be elicited by these low concentrations of Cd at longer exposure periods. Therefore, biomarkers and histopathology in combination provide early-warning indications of altered health status after waterborne Cd exposure in sole juveniles, a prospective sentinel for biological effects assessment of metal contamination in pollution monitoring programs in estuaries and coastal areas.

AVALIAÇÃO DOS ALTOS NÍVEIS DE ATIVIDADE ESPORTIVA E O EFEITO BENÉFICO NOS PERFIS DE GLICEMIA PÓS-PRANDIAL

ABSTRACT Introduction: Hyperglycemia is the principal characteristic component of type 2 diabetes. High blood glucose concentrations for long periods can be countered with postprandial exercise by increasing glucose retention involuntary muscles. However, no research is present on the relationship between exercise time and glucose levels. Objective: This study evaluates the relationship between sports activity and postprandial glycemia levels. Methodology: Forty-five individuals were included in the study, 10 males and 35 females with an age of 27.11±2.8 years; a body fat percentage of 25.02% ±5.04%; and a body mass index of 22.74±4.55 kg/m2. Participants were included via WhatsApp for daily information on postprandial activity levels. WhatsApp messages were forwarded to a total of 2,500 people at different colleges and universities. Out of the total 60 active people (2.40%) who responded, 45 individuals participated in the study. They were divided into three categories based on self-reported postprandial activity: not very active (15), quite active (15), highly active (15). All active individuals completed an oral glucose intake test with blood samples obtained for evaluation at 15, 30, 45, 60, 90, and 120 minutes post-rest. On a gender basis, the groups could not be associated (P =.057). Results: All active groups showed a remarkable effect on blood glucose level at one hour (P =.031). A mean increase in blood glucose level in the first hour of 1.50 mmol/L was observed for every extra 1.0 mmol/L of standard glycemic amount, on average, women had a higher blood glucose amount of 1.35 mmol/L than men. Conclusion: It can be concluded that a high amount of postprandial activity generates a good outcome on glycemic parameters. Evidence Level II; Therapeutic Studies – Investigating the results.

Stability of respiratory-like droplets under evaporation

Recent studies have shown that enveloped viruses contained in airborne respiratory droplets lose infectability fastest at intermediate ambient relative humidities. Studying the evaporation dynamics of respiratory-like droplets in air reveals that, at high humidity, the salt dissolved in respiratory drops inhibits their evaporation indefinitely while at low humidity the drop evaporates leaving a porous solid residue, inside which virions may survive for long times. We conclude that the optimal relative humidity for minimal infectability should coincide with that at which droplets remain liquid and contain high salt concentrations for long periods of time.

The possible role of folic acid against sodium fluoride induced toxicity in the skin of adult male albino rats.

Background:Exposure of human being to fluoride occurs through various sources as food, water, toothpastes and fluoride additives. This exposure is either to low concentrations for long periods or to high concentrations and both may lead to poisoning. Folic acid (FA) has an important free radical scavenging property which makes it the most potent antioxidants. Moreover, it suppresses apoptosis and boost cell survival. Aim of the work: To evaluate the protective and therapeutic role of FA against sodium fluoride (NaF) induced toxicity on adult male rat skin. Materials and Methods:Forty adult (3 months) male albino rats(weighing 200-220 gm) were equally divided into 4 groups (10 rats each):group 1 (control),group 2 (NaF, for 4 weeks),group 3 (NaF, for 4 weeks followed by FA for another 4 weeks) and group 4 (NaF plus FA for 4 weeks). Both NaF (25mg/Kg b.w.) and FA (8 mg/Kg b.w.) were given orally daily. The rats were sacrificed and samples of the back skin were processed for histological, immunohistochemical (Bcl2 antiapoptotic protein) and morphometric studies. Results:Group 2 revealed signs of degeneration in epidermal cells, expansion of intercellular spaces and destructed organelles. There wasa reduction in epidermal thickness with disturbance in collagen fibers arrangement and weak immunoreactivity of Bcl-2. FA induced relative improvement in the dermal and epidermal structures in group 3 while there was preservation of these structures in group 4. Conclusion:FA ameliorates NaF induced harmful effects on skin in addition to its valuable preventive role.

Influence of Curing Condition on Properties of Solidified Clay in Landfill Leachate Environment

The experiments were performed to investigate the engineering properties and microstructure of cutoff wall in terms of clay‐solidifying agent (CSA; or cement) contents, landfill leachate concentrations and curing time. The solidified clay was produced from leachate contaminated clay and cured in leachate of same concentration. The results indicate that CSA becomes the dominant factor influencing the property of solidified clay when the content of CSA exceeds 20% and CSA decreases the porosity instead of pore‐size distribution of solidified clay. In earlier curing period, hydration of CSA takes effect, and the leachate corrosion plays a dominant role after 28 days because most of the hydration completes. While leachate cannot greatly change the pore‐size distribution of solidified clay in 28 days curing time until leachate concentration exceeded 60% that is defined as critical concentration in this test. When the leachate concentration is relatively high, the aggravated corrosion occurs and a minor concentration increase will induce a drastically intensified damage in solidified clay. In engineering applications, it is crucial to prevent cutoff wall from contacting leachate of high concentration for long periods. © 2019 American Institute of Chemical Engineers Environ Prog, 38:e13146, 2019

WORK- RELATED MUSCULOSKELETAL SYMPTOMS AMONG NURSE STAFF IN ISMAILIA, EGYPT

Introduction: Nursing career is considered one of the most physically laborious professions which are associated with high prevalence of work related musculoskeletal disorders (WMSDs). Although the latter is of major concern worldwide; limited epidemiological studies on WMSDs among nurses for referencing in Egypt. Aim of work:1) Assessing the prevalence of work related musculoskeletal symptoms (MSSs) among nurses in Suez Canal University Hospital and Ismailia General Hospital, 2) determining the associations between personal and occupational characteristics, physical risk factors with MSSs of back, neck, knee, wrist and shoulder and, 3) determining the relationship between presence of musculoskeletal symptoms and its sequel. Materials and methods: A cross sectional study is implemented on 135 female nurses with full history taking including medical and occupational histories. A modified form of Standardized Nordic Questionnaire (SNQ) and medical history checklist for symptoms of WMSDs from Canadian Center for Occupational Health and Safety is used for detection and assessment of musculoskeletal symptoms. Results: About 113(83.7%) of the participants reported musculoskeletal symptoms: 91.4% in inpatient and ICU and 77.90% in outpatient. The most prevalent site was lower back (79.3%, 58.4%) in inpatient, ICU and outpatients respectively, working in awkward positions and presence of work related symptoms with (OR:22.259, CI:4.58-108.10)(p<0.05), concentration for long periods(OR:0.25, CI:0.07-0.95) (p<0.05) presence of work shifts(OR:0.1.25, CI:1.14-1.38) (p<0.05) are the most perceived predictors for MSSs. Conclusion: A high frequency of Egyptian nurses reported WMSDs at some body sites; with the low back being the most injured site. Nurses in inpatients and ICU departments were more affected than outpatients. Working in awkward positions for long periods, presence of working shifts and concentration for long periods were the most perceived job risk factors.

Validation of a Bayesian Adaptive Estimation Technique in the Stop-Signal Task.

The Stop Signal Task (SST), a commonly used measure of response inhibition, uses standard psychophysical methods to gain an estimate of the time needed to withhold a prepotent response. Under some circumstances, conventional forms of the SST are impractical to use because of the large number of trials necessary to gain a reliable estimate of the speed of inhibition. Here we applied to the SST an adaptive method for estimating psychometric parameters that can find reliable threshold estimates over a relatively small number of trials. The Ψ adaptive staircase, which uses a Bayesian algorithm to find the most likely parameters of a psychophysical function, was used to estimate the critical stop signal delay at which the probability of successful response inhibition equals 0.5. Using computational modeling and adult participants, estimates of stop signal reaction time (SSRT) based on the Ψ staircase were compared to estimates using the method of constant stimuli and a standard staircase method of adjustment. Results demonstrate that a reliable estimate of SSRT can be gained very quickly (20–30 stop trials), making the method very useful for testing populations that cannot maintain concentration for long periods or for rapidly obtaining multiple SSRT estimates from healthy adult participants.

The Role of AMPK‐SIRT1 Pathway in High Glucose‐Induced Insulin Resistance in Rat Cultured Podocytes

Podocytes insulin sensitivity is critical for glomerular function and the loss of correct insulin signaling in consequence leads to alterations and disorders featuring diabetic nephropathy. The energy sensing pathways, like AMP‐dependent protein kinase (AMPK), and class III protein deacetylase SIRT1 have been shown to play an important role in insulin resistance.The aim of this study was determination of the role of AMPK and SIRT1 in insulin resistance of podocytes exposed to high glucose concentration. Experiments were performed in primary rat podocytes cultured with normal (NG, 11.1 mM) or high (HG, 30 mM) glucose concentrations for 5 days. Insulin‐stimulated changes in glucose uptake were used to detect insulin resistance.HG decreased the phosphorylation of AMPK by about 20% (P&lt;0.05) and abolished insulin‐stimulated glucose uptake into podocytes. Knockdown of SIRT1 protein expression in NG‐cultured podocytes decreased AMPK phosphorylation by about 30% and abolished insulin‐stimulated glucose uptake. The stimulating effect of resveratrol (RSV) on AMPK phosphorylation was observed in cells cultured in NG or HG medium, by about 50% and 65%, respectively. Glucose uptake was also increased in HG‐cultured podocytes treated with RSV.We found that impairment of insulin induction of glucose uptake into podocytes cultivated in the presence of high glucose concentrations for long periods of time is associated with decreased AMPK phosphorylation in an SIRT1‐dependent manner. This work was supported by grant from the National Science Centre (Grant 2012/05/N/NZ5/01448).

Key factors for determining groundwater impacts due to leakage from geologic carbon sequestration reservoirs

In this paper we describe potential impacts to groundwater quality due to CO2 and brine leakage, discuss an approach to calculate thresholds under which “no impact” to groundwater occurs, describe the time scale for impact on groundwater, and discuss the probability of detecting a groundwater plume should leakage occur. To facilitate this, multi-phase flow and reactive transport simulations and reduced-order models were developed for two classes of aquifers, considering uncertainty in leakage source terms and aquifer hydrogeology. We targeted an unconfined fractured carbonate aquifer based on the Edwards Aquifer in Texas and a confined alluvium aquifer based on the High Plains Aquifer in Kansas, which share characteristics typical of many drinking water aquifers in the United States. The hypothetical leakage scenarios centered on the notion that wellbores are the most likely conduits for brine and CO2 leaks. Leakage uncertainty was based on hypothetical injection of CO2 for 50 years at a rate of 5 million tons per year into a depleted oil/gas reservoir with high permeability and, one or more wells provided leakage pathways from the storage reservoir to the overlying aquifer. This scenario corresponds to a storage site with historical oil/gas production and some poorly completed legacy wells that went undetected through site evaluation, operations, and post-closure.For the aquifer systems and leakage scenarios studied here, CO2 and brine leakage are likely to drive pH below and increase total dissolved solids (TDS) above the “no-impact thresholds”; and the subsequent plumes, although small, are likely to persist for long periods of time in the absence of remediation. In these scenarios, however, risk to human health may not be significant for two reasons. First, our simulated plume volumes are much smaller than the average inter-well spacing (1–2.6wells/km2) for these representative aquifers, so the impacted groundwater would be unlikely to be pumped for drinking water. Second, even within the impacted plume volumes little water exceeds the primary maximum contamination levels. These observations point to:•The potential utility of uncertainty quantification methods to evaluate the risk of leakage and inform monitoring and corrective action plans of a potential site for long-term CO2 storage by capturing storage reservoir, leakage pathway, and aquifer heterogeneity.•The importance of establishing baseline groundwater chemistry that captures the pre-injection variability of underground sources of drinking water (USDW) above the reservoir because the EPA has adopted a “no net degradation” policy toward the protection of groundwater resources.•The need to test and develop spatially diverse monitoring techniques capable of detecting leakage early to employ effective mitigation strategies, and more importantly to add confidence to assessments used to evaluate the length of the post-injection site care. In our study, the probability of detecting plumes using existing wells to sample the groundwater chemistry was very low, because the plumes were relatively small in both aquifers.•The need to develop methodologies that prevent and/or directly detect leakage prior to reaching USDWs, because our simulations predict that even small amounts of CO2 and brine, when left unmitigated, can change USDW pH and TDS concentrations for long periods of time.

Involvement of the AMPK–PTEN pathway in insulin resistance induced by high glucose in cultured rat podocytes

As part of the filtration barrier, podocytes play an important role in the development of diabetic nephropathy. Disturbances in insulin signaling accompanied by insulin resistance can lead to various intracellular events. We hypothesized that high glucose concentrations would lead to disturbances in interactions between AMPK and PTEN proteins in podocytes. Experiments were performed in primary rat podocytes cultured with normal (5.6mM) or high (30mM) glucose concentrations for 5d. Immunodetection methods were used to detect AMPK, PTEN, insulin receptor, and Akt proteins, and their phosphorylated forms. Insulin-stimulated changes in glucose uptake were used to detect insulin resistance. Isoforms of AMPK were detected by RT-PCR. AMPK and PTEN activities were modified by metformin, Compound C, siRNA for AMPK isoforms α1 and α2 and siRNA for PTEN, respectively. We found that impairment of insulin induction of glucose uptake into podocytes cultivated in the presence of high glucose concentrations for long periods of time is associated with increased PTEN levels in an AMPK-dependent manner.

Growth of Myxococcus xanthus in Continuous-Flow-Cell Bioreactors as a Method for Studying Development

Nutrient sensors and developmental timers are two classes of genes vital to the establishment of early development in the social soil bacterium Myxococcus xanthus. The products of these genes trigger and regulate the earliest events that drive the colony from a vegetative state to aggregates, which ultimately leads to the formation of fruiting bodies and the cellular differentiation of the individual cells. In order to more accurately identify the genes and pathways involved in the initiation of this multicellular developmental program in M. xanthus, we adapted a method of growing vegetative populations within a constant controllable environment by using flow cell bioreactors, or flow cells. By establishing an M. xanthus community within a flow cell, we are able to test developmental responses to changes in the environment with fewer concerns for effects due to nutrient depletion or bacterial waste production. This approach allows for greater sensitivity in investigating communal environmental responses, such as nutrient sensing. To demonstrate the versatility of our growth environment, we carried out time-lapse confocal laser scanning microscopy to visualize M. xanthus biofilm growth and fruiting body development, as well as fluorescence staining of exopolysaccharides deposited by biofilms. We also employed the flow cells in a nutrient titration to determine the minimum concentration required to sustain vegetative growth. Our data show that by using a flow cell, M. xanthus can be held in a vegetative growth state at low nutrient concentrations for long periods, and then, by slightly decreasing the nutrient concentration, cells can be allowed to initiate the developmental program.

Uptake, transfer and elimination kinetics of paralytic shellfish toxins in common octopus (Octopus vulgaris)

Marine phycotoxins derived from harmful algal blooms are known to be associated with mass mortalities in the higher trophic levels of marine food webs. Bivalve mollusks and planktivorous fish are the most studied vectors of marine phycotoxins. However, field surveys recently showed that cephalopod mollusks also constitute potential vectors of toxins. Thus, here we determine, for the first time, the time course of accumulation and depuration of paralytic shellfish toxins (PSTs) in the common octopus (Octopus vulgaris). Concomitantly, the underlying kinetics of toxin transfer between tissue compartments was also calculated. Naturally contaminated clams were used to orally expose the octopus to PSTs during 6 days. Afterwards, octopus specimens were fed with non-contaminated shellfish during 10 days of depuration period. Toxins reached the highest concentrations in the digestive gland surpassing the levels in the kidney by three orders of magnitude. PSTs were not detected in any other tissue analyzed. Net accumulation efficiencies of 42% for GTX5, 36% for dcSTX and 23% for C1+2 were calculated for the digestive gland. These compounds were the most abundant toxins in both digestive gland and the contaminated shellfish diet. The small differences in relative abundance of each toxin observed between the prey and the cephalopod predator indicates low conversion rates of these toxins. The depuration period was better described using an exponential decay model comprising a single compartment – the entire viscera. It is worth noting that since octopuses’ excretion and depuration rates are low, the digestive gland is able to accumulate very high toxin concentrations for long periods of time. Therefore, the present study clearly shows that O. vulgaris is a high-potential vector of PSTs during and even after the occurrence of these toxic algal blooms.

Osteomyelitis: an overview of antimicrobial therapy

Osteomyelitis is an inflammatory bone disorder caused by infection, leading to necrosis and destruction of bone. It can affect all ages, involve any bone, become a chronic disease and cause persistent morbidity. Treatment of osteomyelitis is challenging particularly when complex multiresistant bacterial biofilm has already been established. Bacteria in biofilm persist in a low metabolic phase, causing persistent infection due to increased resistance to antibiotics. Staphylococcus aureus and Staphylococcus epidermidis are the most common causative organism responsible for more than 50% of osteomyelitis cases. Osteomyelitis treatment implies the administration of high doses of antibiotics (AB) by means of endovenous and oral routes and should take a period of at least 6 weeks. Local drug delivery systems, using non-biodegradable (polymethylmethacrylate) or biodegradable and osteoactive materials such as calcium orthophosphates bone cements, have been shown to be promising alternatives for the treatment of osteomyelitis. These systems allow the local delivery of AB in situ with bactericidal concentrations for long periods of time and without the toxicity associated with other means of administration. This review examines the most recent literature evidence on the causes, pathogeneses and pharmacological treatment of osteomyelitis. The study methodology consisted of a literature review in Google Scholar, Science Direct, Pubmed, Springer link, B-on. Papers from 1979 till present were reviewed and evaluated.

Short exposure of albumin to high concentrations of malondialdehyde does not mimic physiological conditions

Malondialdehyde (MDA), a major lipid peroxidation product, spontaneously binds to, and modifies proteins. In vivo, proteins are physiologically exposed to micromolar MDA concentrations for long periods. In order to mimic this process in vitro, protein modification is often performed by short exposure to millimolar MDA concentrations, also in order to generate antigenic structures for antibody production.However, in our study, spectrophotometric and fluorimetric characteristics, electrophoretic migration, susceptibility to trypsin digestion and reactivity to antibodies indicated substantial differences between albumin incubated with millimolar MDA concentrations for a short period of time and albumin incubated with micromolar MDA concentrations for a long period of time. Therefore, our study showed that short incubation of albumin with millimolar MDA concentrations does not mimic the consequences of albumin exposure to long incubation with micromolar MDA concentrations.This casts doubts on the real possibility that antibodies, elicited with proteins modified with millimolar MDA concentrations for a short period, could detect all MDA-modified proteins in vivo.Moreover, natural antibodies against albumin, modified with micromolar MDA concentrations, have been detected in the serum of healthy blood donors, which appears to justify the existence of these kinds of modified proteins in vivo.

Microfluidic dialysis cell for characterization of macromolecule interactions

Microfluidic dialysis is a promising tool for characterisation of macromolecule interactions and responsive materials, but until now it has been limited to the characterisation of high molecular weight molecules. Here, we introduce a low molecular weight cut-off dialysis membrane fabricated by coating a rigid membrane filter with a layer of crosslinked hydrogel. The modified hybrid silicone/glass microfluidic cells retain low molecular weight samples at a well-defined concentration for long periods of time, while allowing timely changes to be made in the fluid's supporting solvent (i.e. pH, ionic strength, ionic species). Straightforward access to the sample using high-resolution optical microscopy enables in situ characterisation of the sample's physical properties in response to changes in solvent conditions. A proof of principle measurement investigating the pH-sensitive binding between the protein/polysaccharide pair, neurocan and hyaluronan, is presented to demonstrate the integration of protein retention, solvent switching and fluorescence recovery after photobleaching (FRAP).

Adaptive Experience Engine for Serious Games

Designing games that support knowledge and skill acquisition has become a promising frontier of education techniques, since games are able to capture the user concentration for long periods and can present users with realistic and compelling challenges. In this scenario, there is a need for scientific and engineering methods to build games not only as more realistic simulations of the physical world but as means to provide effective learning experiences. Abstracting state of the art serious games' (SGs) features, we propose a new design methodology for the sand box serious games (SBSGs) class, decoupling content from the delivery strategy during the gameplay. This methodology aims at making design more efficient and standardized in order to meet the growing demand for interactive learning. The methodology consists in modeling an SBSG as a hierarchy of tasks (e.g., missions) and specifies the requirements for a runtime scheduling policy that maximizes learning objectives in a full entertainment context. The policy is learned by an experience engine (EE) based on computational intelligence. In this approach, the domain-expert author focuses on the creation and semantic annotation of tasks. Tasks are put in a repository and can then be exploited by game designers who define the expected learning curve and other requirements about education and entertainment for the game. The task sequencing that aims at matching such specifications with the real user profile is then presented to the EE. The EE can operate also in absence of the specification of the learning curve, continuously adapting the game flow without aiming at the achievement of target knowledge levels predefined by the author. We have implemented an EE module based on genetic computation and reinforcement learning (RL) atop of a state-of-the-art game engine. Test results show that the EE is able to define in real-time missions that meet the requirements expressed by the author.

Myron Cohen ponders path to HIV prevention

Myron Cohen ponders path to HIV prevention

Experimental system to evaluate the effective diffusion coefficient of radon

The effective diffusion coefficient of radon is a very important factor in estimating the rate of radon exhalation from the ground surface. In this study, we developed an experimental system that overcomes technical problems in previous studies to accurately evaluate the effective diffusion coefficient. The radon source used for this system was the National Institute of Radiological Sciences radon chamber. This chamber is a calibrated international standard facility that can produce stable radon concentrations for long periods of time. Our tests showed that leakage of radon from the system was negligible. After the leakage test, we evaluated the effective diffusion coefficient in free-space and in dry porous materials at porosities of 35% and 45%. To ensure that the porous material in the column was as homogeneous as possible, we filled the column with an artificial soil with controlled grain size and grain composition. The measured values and theoretical calculations agreed well, which indicate that the proposed system can be used to accurately and quickly evaluate the effective diffusion coefficient.

Coarse Particles From Saharan Dust and Daily Mortality

Winds from the Sahara-Sahel desert region regularly transport large amounts of dust to the Americas, North Africa, and Europe. The presence of high dust concentrations for long periods of time, and the interaction between dust and man-made air pollution, raise concerns about adverse health effects and appropriate interventions by health authorities. This study tested the hypothesis that outbreaks of Saharan dust exacerbate the effects of man-made pollution, specifically fine and coarse particulate matter (PM2.5 and PM10-2.5, respectively) on daily mortality. We investigated the effects of exposure to PM10-2.5 and PM2.5 between March 2003 and December 2004 in Barcelona (Spain) on daily mortality; changes of effects between Saharan and non-Saharan dust days were assessed using a time-stratified case-crossover design. We studied the chemical composition of particulate matter to explain changes of effects. The study included 24,850 deaths. During Saharan dust days, a daily increase of 10 microg/m3 of PM10-2.5 increased daily mortality by 8.4% (95% confidence interval = 1.5%-15.8%) compared with 1.4% (-0.8% to 3.4%) during non-Saharan dust days (P value for interaction = 0.05). In contrast, there was no increased risk of daily mortality for PM2.5 during Saharan dust days. Although coarse particles seem to be more hazardous during Saharan dust days, differences in chemical composition did not explain these observations. Saharan dust outbreaks may have adverse health effects. Further investigation is needed to understand the role of coarse particles and the mechanism by which Saharan dust increases mortality.