196 research outputs found

    Measurement error caused by spatial misalignment in environmental epidemiology

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    Copyright @ 2009 Gryparis et al - Published by Oxford University Press.In many environmental epidemiology studies, the locations and/or times of exposure measurements and health assessments do not match. In such settings, health effects analyses often use the predictions from an exposure model as a covariate in a regression model. Such exposure predictions contain some measurement error as the predicted values do not equal the true exposures. We provide a framework for spatial measurement error modeling, showing that smoothing induces a Berkson-type measurement error with nondiagonal error structure. From this viewpoint, we review the existing approaches to estimation in a linear regression health model, including direct use of the spatial predictions and exposure simulation, and explore some modified approaches, including Bayesian models and out-of-sample regression calibration, motivated by measurement error principles. We then extend this work to the generalized linear model framework for health outcomes. Based on analytical considerations and simulation results, we compare the performance of all these approaches under several spatial models for exposure. Our comparisons underscore several important points. First, exposure simulation can perform very poorly under certain realistic scenarios. Second, the relative performance of the different methods depends on the nature of the underlying exposure surface. Third, traditional measurement error concepts can help to explain the relative practical performance of the different methods. We apply the methods to data on the association between levels of particulate matter and birth weight in the greater Boston area.This research was supported by NIEHS grants ES012044 (AG, BAC), ES009825 (JS, BAC), ES007142 (CJP), and ES000002 (CJP), and EPA grant R-832416 (JS, BAC)

    Petals of Crocus sativus L. as a potential source of the antioxidants crocin and kaempferol.

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    Collaboration between Leicester School of Pharmacy - De Montfort Universit, Department of Life, Health and Environmental Sciences - University of L'Aquila, and Department of Biochemistry and Biotechnology - University of Thessaly The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Saffron fromthe province of L'Aquila, in the Abruzzo region of Italy, is highly prized and has been awarded a formal recognition by the European Union with EU Protected Designation of Origin (PDO) status. Despite this, the saffron regions are abandoned by the younger generations because the traditional cultivation of saffron (Crocus sativus L.) is labour intensive and yields only one crop of valuable saffron stamens per year. Petals of the saffron Crocus have had additional uses in traditional medicine and may add value to the crops for local farmers. This is especially important because the plant only flowers between October andNovember, and farmers will need to make the best use of the flowers harvested in this period. Recently, the petals of C. sativus L., which are considered a wastematerial in the production of saffron spice,were identified as a potential source of natural antioxidants. The antioxidants crocin and kaempferol were purified by flash column chromatography, and identified by thin layer chromatography (TLC), HPLC–DAD, infrared (IR), and nuclear magnetic resonance (1H & 13C NMR) spectroscopy. The antioxidant activity was determined with the ABTS and DPPH tests. The antioxidant activities are mainly attributed to carotenoid and flavonoid compounds, notably glycosides of crocin and kaempferol. We found in dried petals 0.6% (w/w) and 12.6 (w/w) of crocin and kaempferol, respectively. Petals of C. sativus L. have commercial potential as a source for kaempferol and crocetin glycosides, natural compounds with antioxidant activity that are considered to be the active ingredients in saffron-based herbal medicine

    In vitro biocompatibility of a new hydrogel with Crocin, powerful antioxidant found in Crocus Sativus L. flowers

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    Recently, attention has been paid to the identification of natural antioxidants from the petals of Crocus S. flowers that are normally considered waste[1]. The antioxidant activities are mainly attributed to carotenoid compounds, like crocin. Scientific evidences demonstrate that this kind of compounds are among the most important natural plant sources of antioxidant activity in the human diet, protecting the body against damages caused by reactive oxygen species (ROS). This antioxidant was extracted using methanol and ethanol. In this experiment, it was used a new hydrogel consisting of three polymers - Polyvinyl pyrrolidone (PVP), Agar and Polyethylene glycol (PEG) – and Crocin, mixed, reticulated and then sterilized by gamma irradiation at 25 kGy. For the in vitro experimental protocol, it was used a primary culture of fibroblasts taken from the subcutaneous tissue of a newborn mice, seeding the cells on a little square (1cm2 area) of both kinds of hydrogel. As the ISO protocol prescribes, the experiments were repeated 3 times for each kind of hydrogel, stopping the culture at the 3rd, 7th and 14th day after the seeding. For all steps, 3 Petri dishes were used as controls without biomaterials. At fixed deadline, all Petri dishes were stained, using the Wright method for cell counting and morphological evaluations. The microscopic analysis revealed the complete biocompatibility of the hydrogel. The Petri dishes with this kind of new hydrogel has an overproduction of collagen from the fibroblasts. The presence of this natural important compound in saffron petals, now offers new possibilities for the best use of the hole flower. This study is still in progress.http://www.fupress.net/index.php/ijae/article/view/1495

    Development of a new protocol: a macroscopic study of the tongue dorsal surface

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    The presence on the dorsal tongue of additional irregularities such as fissures, grooves and the distribution of papillae constitutes a retention area for harbouring bacteria, particularly those that produce sulphur compounds. A protocol to study the morphology of the tongue in a macroscopic way was developed, aimed at better investigating on the relationship between the dorsal surface of the tongue, considered as a microbial ecosystem, and the oral halitosis (1). A patient affected by oral malodour was chosen and included in the study. A picture of his lingual dorsum was taken to show the areas where the coating was visible. Then, an impression with alginate was taken obtaining a replication in plaster and, on the base of this one, a sort of impression tray was modelled utilizing an impression material made of silicone putty. After this, a second impression was taken combining the tray in silicone putty with a silicone material having a very low-light density (using the 2-step double-mix impression technique). The impression obtained was divided and cut with a blade in six parts, according to Winkel Tongue Coated Index (2), and their contour was observed with the stereo-microscope. The images were analysed with the Image J programme, and the parameter considered was the depth among the papillae. The mean measure of this parameter, in the parts where the coating was visible, resulted in a range between 0,25 + 0,019 mm and 0,55 + 0,11 mm. The same measures in the parts where the coating was not visible swung instead in a range between 0,14 + 0,08 mm and 0,23 + 0,07 mm. This new protocol can be considered clinically relevant for the suitable diagnosis and for the personalized treatment of halitosis

    Activity of Antioxidants from Crocus sativus L. Petals: Potential Preventive Effects towards Cardiovascular System

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    The petals of the saffron crocus (Crocus sativus L.) are considered a waste material in saffron production, but may be a sustainable source of natural biologically active substances of nutraceutical interest. The aim of this work was to study the cardiovascular effects of kaempferol and crocin extracted from saffron petals. The antiarrhythmic, inotropic, and chronotropic effects of saffron petal extract (SPE), kaempferol, and crocin were evaluated through in vitro biological assays. The antioxidant activity of kaempferol and crocin was investigated through the 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) assay using rat cardiomyoblast cell line H9c2. The MTT assay was applied to assess the effects of kaempferol and crocin on cell viability. SPE showed weak negative inotropic and chronotropic intrinsic activities but a significant intrinsic activity on smooth muscle with a potency on the ileum greater than on the aorta: EC50 = 0.66 mg/mL versus EC50 = 1.45 mg/mL. Kaempferol and crocin showed a selective negative inotropic activity. In addition, kaempferol decreased the contraction induced by KCl (80 mM) in guinea pig aortic and ileal strips, while crocin had no effect. Furthermore, following oxidative stress, both crocin and kaempferol decreased intracellular ROS formation and increased cell viability in a concentration-dependent manner. The results indicate that SPE, a by-product of saffron cultivation, may represent a good source of phytochemicals with a potential application in the prevention of cardiovascular diseases

    New resveratrol analogues for potential use in diabetes and cancer.

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    open access journalResveratrol is a well notorious compound that may play a role in the prevention of diabetes complications and different cancers. Along, resveratrol, a naturally occurring phytoalexin, is known to exert numerous beneficial effects in the organism. Isolation of resveratrol from plants, however, has been proved being difficult. Importantly, the bioavailability in the body is poor therefore capability is reduced and not enough resveratrol reaches the target organ. In this study we generated different methoxylated resveratrol analogues using Wittig reaction. Trans stilbene obtained was 0.08 g and the cis one was 0.01 g. Additionally with the Horner-Witting method a yield of 0.15 g trans stilbene was obtained. By substituting the hydroxyl group with methoxy group at different positions on the aromatic rings, we could increase the efficacy and bioavailability of the Trans form of resveratrol
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