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FATIGUE LIFE PREDICTION BY THE STRUCTURALLY SENSITIVE DAMAGE INDICATOR Прогнозування втомно довгов чност за допомогою структурно-чутливого ндикатора пошкодження
Mikhail Karuskevich
Proceedings of National Aviation University , 2012,
Abstract: The investigations of the new fatigue sensor that was carried out at the wide range of cyclicloads conditions show the ability of the indicator application in Structural Health Monitoringsystems of planes, bridges, vessels, and other structures. Accumulated fatigue damage may byestimated by the intensity of deformation relief, i.e. by its extrusion/intrusion and persistent slipbands structures on the indicator surface.Keywords: alelad aluminum alloys, deformation relief, fatigue, fatigue indicator.Розглянуто результати досл дження нового ндикатора втоми, проведених в широкомуд апазон режим в цикл чного навантажування. Показано можлив сть застосування ндикатора всистемах контролю техн чного стану л так в, мост в, корабл в та нших конструкц й.Накопичене втомне пошкодження визначено за нтенсивност деформац йного рель фуповерхн , який формують екструз , нтруз стал смуги ковзання на поверхн ндикатора.Ключов слова: втома, деформац йний рель ф, ндикатор втоми, плакований алюм н вийсплав. Розглянуто результати досл дження нового ндикатора втоми, проведених в широкомуд апазон режим в цикл чного навантажування. Показано можлив сть застосування ндикатора всистемах контролю техн чного стану л так в, мост в, корабл в та нших конструкц й. Накопичене втомне пошкодження визначено за нтенсивност деформац йного рель фуповерхн , який формують екструз , нтруз стал смуги ковзання на поверхн ндикатора.
Methylmalonic acid as an indicator of vitamin B12 deficiency in patients on metformin  [PDF]
Norbert Shtaynberg, Manjinder Singh, Phillip Sohn, Michael Goldman, Neil Cohen
Journal of Diabetes Mellitus (JDM) , 2012, DOI: 10.4236/jdm.2012.21011
Abstract: Context: Metformin is frequently prescribed for the treatment of type 2 diabetes mellitus. It is recommended as a first line agent by the American Diabetes Association. Vitamin B12 deficiency has been suggested as a side effect of metformin therapy; however, previous studies have not assessed the utility of methylmalonic acid levels as an indicator of vitamin B12 status. Objective: To investigate the prevalence of vitamin B12 deficiency in patients on metformin therapy for diabetes by utilizing both vitamin B12 and methylmalonic acid levels. Design, Setting, and Patients: Eighty-eight patients with diabetes, who were either on or off metformin therapy for at least thirty days, were enrolled in a case-controlled study. Blood work and questionnaires were used for analysis. Main Outcome Measures Study: Aims were to detect a clinically significant difference in the prevalence of vitamin B12 deficiency between metformin users and non-users, where such deficiency is defined by both low vitamin B12 and elevated methylmalonic acid levels. Results: Two Sample Equal Variance T-Tests were used to compare averages of measured values and the Chisquare test was used to determine the significance of calculated vitamin B12 deficiency rates between the two groups of patients. Two separate methods for defining vitamin B12 deficiency were utilized. There was no difference in the prevalence of vitamin B12 deficiency in metformin users compared with non-users by either method. Average homocysteine levels were higher in those not on metformin therapy. Conclusion: Vitamin B12 deficiency as defined by an elevated methylmalonic acid level was no greater in patients with diabetes on metformin therapy versus those patients not on metformin treatment.
ROCK1 Deficiency Enhances Protective Effects of Antioxidants against Apoptosis and Cell Detachment  [PDF]
Michelle Surma, Caitlin Handy, Jiang Chang, Reuben Kapur, Lei Wei, Jianjian Shi
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0090758
Abstract: We have recently reported that the homologous Rho kinases, ROCK1 and ROCK2, play different roles in regulating stress-induced stress fiber disassembly and cell detachment, and the ROCK1 deficiency in mouse embryonic fibroblasts (MEF) has remarkable anti-apoptotic, anti-detachment and pro-survival effects against doxorubicin, a chemotherapeutic drug. This study investigated the roles of ROCK isoforms in doxorubicin-induced reactive oxygen species (ROS) generation which is believed to be the major mechanism underlying its cytotoxicity to normal cells, and especially to cardiomyocytes. Different antioxidants have been shown to provide a protective role reported in numerous experimental studies, but clinical trials of antioxidant therapy showed insufficient benefit against the cardiac side effect. We found that both ROCK1?/? and ROCK2?/? MEFs exhibited reduced ROS production in response to doxorubicin treatment. Interestingly, only ROCK1 deficiency, but not ROCK2 deficiency, significantly enhanced the protective effects of antioxidants against doxorubicin-induced cytotoxicity. First, ROCK1 deficiency and N-acetylcysteine (an anti-oxidant) treatment synergistically reduced ROS levels, caspase activation and cell detachment. In addition, the reduction of ROS generation in ROCK1?/? MEFs in response to doxorubicin treatment was in part through inhibiting NADPH oxidase activity. Furthermore, ROCK1 deficiency enhanced the inhibitory effects of diphenyleneiodonium (an inhibitor of NADPH oxidase) on ROS generation and caspase 3 activation induced by doxorubicin. Finally, ROCK1 deficiency had greater protective effects than antioxidant treatment, especially on reducing actin cytoskeleton remodeling. ROCK1 deficiency not only reduced actomyosin contraction but also preserved central stress fiber stability, whereas antioxidant treatment only reduced actomyosin contraction without preserving central stress fibers. These results reveal a novel strategy to enhance the protective effect of antioxidant therapy by targeting the ROCK1 pathway to stabilize the actin cytoskeleton and boost the inhibitory effects on ROS production, apoptosis and cell detachment.
Neonatal Thyroid-Stimulating Hormone Concentrations in Belgium: A Useful Indicator for Detecting Mild Iodine Deficiency?  [PDF]
Stefanie Vandevijvere, Wim Coucke, Jean Vanderpas, Caroline Trumpff, Maarten Fauvart, Ann Meulemans, Sandrine Marie, Marie-Fran?oise Vincent, Roland Schoos, Fran?ois Boemer, Timothy Vanwynsberghe, Eddy Philips, Fran?ois Eyskens, Brigitte Wuyts, Valbona Selimaj, Bart Van Overmeire, Christine Kirkpatrick, Herman Van Oyen, Rodrigo Moreno-Reyes
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047770
Abstract: It has been proposed that neonatal thyroid-stimulating hormone (TSH) concentrations are a good indicator of iodine deficiency in the population. A frequency of neonatal TSH concentrations above 5 mU/L below 3% has been proposed as the threshold indicating iodine sufficiency. The objective of the present study was to evaluate feasibility and usefulness of nation-wide neonatal TSH concentration screening results to assess iodine status in Belgium. All newborns born in Belgium during the period 2009–2011 (n = 377713) were included in the study, except those suffering from congenital hypothyroidism and premature neonates. The frequency of neonatal TSH concentrations above 5 mU/L from 2009 to 2011 in Belgium fluctuated between 2.6 and 3.3% in the centres using the same TSH assay. There was a significant inverse association between neonatal TSH level and birth weight. The longer the duration between birth and screening, the lower the TSH level. Neonatal TSH levels were significantly lower in winter than in spring or autumn and significantly lower in spring and summer than in autumn while significantly higher in spring compared to summer. In conclusion, despite that pregnant women in Belgium are mildly iodine deficient, the frequency of neonatal TSH concentrations above 5 mU/L was very low, suggesting that the neonatal TSH threshold proposed for detecting iodine deficiency needs to be re-evaluated. Although neonatal TSH is useful to detect severe iodine deficiency, it should not be recommended presently for the evaluation of iodine status in mildly iodine deficient regions.
Antioxidants Keep the Potentially Probiotic but Highly Oxygen-Sensitive Human Gut Bacterium Faecalibacterium prausnitzii Alive at Ambient Air  [PDF]
M. Tanweer Khan, Jan Maarten van Dijl, Hermie J. M. Harmsen
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0096097
Abstract: The beneficial human gut microbe Faecalibacterium prausnitzii is a ‘probiotic of the future’ since it produces high amounts of butyrate and anti-inflammatory compounds. However, this bacterium is highly oxygen-senstive, making it notoriously difficult to cultivate and preserve. This has so far precluded its clinical application in the treatment of patients with inflammatory bowel diseases. The present studies were therefore aimed at developing a strategy to keep F. prausnitzii alive at ambient air. Our previous research showed that F. prausnitzii can survive in moderately oxygenized environments like the gut mucosa by transfer of electrons to oxygen. For this purpose, the bacterium exploits extracellular antioxidants, such as riboflavin and cysteine, that are abundantly present in the gut. We therefore tested to what extent these antioxidants can sustain the viability of F. prausnitzii at ambient air. The present results show that cysteine can facilitate the survival of F. prausnitzii upon exposure to air, and that this effect is significantly enhanced the by addition of riboflavin and the cryoprotectant inulin. The highly oxygen-sensitive gut bacterium F. prausnitzii can be kept alive at ambient air for 24 h when formulated with the antioxidants cysteine and riboflavin plus the cryoprotectant inulin. Improved formulations were obtained by addition of the bulking agents corn starch and wheat bran. Our present findings pave the way towards the biomedical exploitation of F. prausnitzii in redox-based therapeutics for treatment of dysbiosis-related inflammatory disorders of the human gut.
Gluten sensitive enteropathy in patients with iron deficiency anemia of unknown origin  [cached]
Farhad Zamani, Mehdi Mohamadnejad, Ramin Shakeri, Afsaneh Amiri, Safa Najafi, Seyed Meysam Alimohamadi, Seyed Mohamad Tavangar, Ardeshir Ghavamzadeh, Reza Malekzadeh
World Journal of Gastroenterology , 2008,
Abstract: AIM: To determine the prevalence of gluten sensitive enteropathy (GSE) in a large group of patients with iron deficiency anemia (IDA) of obscure origin.METHODS: In this cross-sectional study, patients with IDA of obscure origin were screened for GSE. Anti-endomysial antibody (EMA) and tissue transglutaminase antibody (tTG) levels were evaluated and duodenal biopsies were taken and scored according to the Marsh classification. The diagnosis of GSE was based on a positive serological test and abnormal duodenal histology. Gluten free diet (GFD) was advised for all the GSE patients.RESULTS: Of the 4120 IDA patients referred to our Hematology departments, 206 (95 male) patients were found to have IDA of obscure origin. Thirty out of 206 patients (14.6%) had GSE. The mean age of GSE patients was 34.6 ± 17.03 (range 10-72 years). The female to male ratio was 1.3:1. Sixteen patients had Marsh 3, 12 had Marsh 2, and 2 had Marsh 1 lesions. The severity of anemia was in parallel with the severity of duodenal lesions. Twenty-two GSE patients (73.3%) had no gastrointestinal symptoms. Fourteen GSE patients who adhered to GFD without receiving iron supplementation agreed to undergo follow up visits. After 6 mo of GFD, their mean hemoglobin levels (Hb) increased from 9.9 ± 1.6 to 12.8 ± 1.0 g/dL (P < 0.01). Interestingly, in 6 out of 14 patients who had Marsh 1/2 lesions (e.g. no villous atrophy) on duodenal biopsy, mean Hb increased from 11.0 ± 1.1 to 13.1 ± 1.0 g/dL (P < 0.01) while they did not receive any iron supplementation.CONCLUSION: There is a high prevalence (e.g. 14.6%) of GSE in patients with IDA of obscure origin. Gluten free diet can improve anemia in GSE patients who have mild duodenal lesions without villous atrophy.
Role of Oxidative Stress and Antioxidants in Children with IDA
Parasuram Melarcode Krishnamoorthy,Natesh Prabu R,Mohan D.M,Sabitha N
International Journal of Collaborative Research on Internal Medicine & Public Health , 2010,
Abstract: Background: Increased oxidative stress with free radical generation in iron deficiency anemia (IDA), its aggravation at therapeutic doses of iron and reduction of oxidative stress by antioxidant supplementation are well studied in adults. Studies in this regard are scanty in children. Objective: The co-prescription of antioxidants with iron supplementation in IDA to counter the oxidative stress is a well studied and established fact in adults .Though iron supplementation is a common clinical practice in children it is not conventional to co-prescribe anti-oxidants in children. Therefore a study was undertaken to evaluate the oxidative stress in IDA in children and the effect of antioxidants during iron supplementation and to evolve an optimal suitable therapeutic strategy to minimize oxidative stress and there by adverse clinical effects. Methods: All the children attending the pediatrics OPD in IRT PMCH during JULY/AUGUST 2008 were randomly screened for anemia by clinical and hemoglobin evaluation. 21 children whose parents gave consent for participation in the study were included for evaluation. They were in the age group of ten months to sixteen years. Nutritional status of the study population was recorded by a twenty four hour recall survey method. After deworming, children were started with oral iron supplementation in three different groups; group I – oral iron only, group II – oral iron with vitamin C, group III – oral iron with vitamin E. Lipid peroxides and Lipid hydroperoxides were measured as the indices of oxidative stress before initiation, tenth day (I follow up), thirtieth day (II follow up) after oral iron therapy. Serum iron profile was also studied for evaluation. Results: There was no significant difference in serum iron profile response to oral iron therapy between the groups. Oxidative stress indices showed a decreasing trend in all the groups with no significant difference among the groups. There were no clinical adverse effects of oral iron supplementation in all the groups. Conclusion: Unlike in adults, oxidative stress in iron deficiency anemia is not aggravated by oral iron supplementation in children. There was no significant difference between oral iron alone and oral iron with antioxidants in terms of clinical and biochemical response. Lipid hydroperoxides seems to be an early indicator of oxidative stress.
Sol-Gel Thin Films Immobilized with Bromocresol Purple pH-Sensitive Indicator in Presence of Surfactants  [PDF]
Nizam M. El-Ashgar,Ahmed I. El-Basioni,Issa M. El-Nahhal,Shehata M. Zourob,Taher M. El-Agez,Sofyan A. Taya
ISRN Analytical Chemistry , 2012, DOI: 10.5402/2012/604389
Abstract: Preparation of transparent sol-gel thin film immobilized with bromocresol purple (BCP) pH-sensitive indicator was made via the acid catalyzed sol-gel reaction of tetraethylorthosilicate and the bromocresol purple indicator (BCP). Different surfactants include cationic cetyl trimethyl ammonium bromide (CTAB), anionic sodium dodecyl sulfate (SDS), and nonionic Triton X-100 (TX-100) were used to improve the mesostructure of the host material and to increase its porosity. The color change behavior of the immobilized bromocresol purple indicator affected significantly in presence of SDS comparing with its free counterpart in aqueous solution. In presence of CTAB and Triton-X 100, the immobilized bromocresol purple indicator shows similar behavior as its free counterpart in aqueous solution. The BCP retains its structure during the sol-gel reactions in terms of response to pH. Different parameters including concentration of indicator and surfactant, temperature, number of layers, response time, life time, and the number of measurements were investigated. The pKa values of the different prepared BCP immobilized thin films were determined. The BCP thin film sensor showed stability, repeatability, reproducibility, fast response, and long life time behavior. The polarized light microscopy indicated that the bromocresol purple indicator molecules are distributed uniformly within the host silica network. 1. Introduction Preparation of sol-gel matrices doped with some chemically and biologically active molecules is a promise route to chemical solid-state sensors [1–4]. The sol-gel technique is one of the most promising tools in material science. The term sol-gel refers to a chemical process where metallic or semimetallic alkoxide precursors or their derivatives form composites at moderate temperatures through a chemical reaction that involves hydrolysis followed by polycondensation [2]. Hydrolysis and polycondensation of tetraethoxysilane in presence of water, organic solvent, and an acid/base catalyst result in the formation of the –Si–O–Si– three-dimensional siloxane network [3–5]. The resulting matrix has high surface area, porosity, inertness, and stability to chemical and physical agents, and optical clarity in the visible and UV ranges [6–8]. Sol-gel matrices appear as a very important technique for immobilization, entrapment, encapsulation for large variety of materials such as organic, inorganic, and biomolecules [9, 10]. The sol-gel materials are ideal candidates as hosts for the analytical reagents because they are synthesized at low concentrations at the
Measurement of stem water potential as a sensitive indicator of water stress in neck orange (Citrus reticulata Blanco)
Sayan Sdoodee,Junjira Somjun
Songklanakarin Journal of Science and Technology , 2008,
Abstract: Measurements of stem water potential, leaf water potential and stomatal conductance were simultaneously done in3-year old trees of neck orange. The trees were subjected to 3 levels of watering: 1) daily watering (control), 2) 4-dayinterval watering and 3) 8-day interval watering. It was found that stem water potential was more sensitive to soil moisturethan leaf water potential. This led to high correlation between soil moisture and stem water potential (r2 = 0.80), but the correlation between soil moisture and leaf water potential was low (r2 = 0.66). Likewise, stomatal conductance was highly correlated with stem water potential (r2 = 0.74). The correlation was higher than that of stomatal conductance with leaf water potential (r2 = 0.62).Therefore, stem water potential appears to be a sensitive indicator to assess water stress in neck orange.
Delay coordinates: a sensitive indicator of nonlinear dynamics in single charged particle motion in magnetic reversals  [cached]
S. C. Chapman,N. W. Watkins
Annales Geophysicae (ANGEO) , 2003,
Abstract: The delay coordinate technique is examined as an indicator of the regime of particle dynamics for the system of single charged particle motion in magnetic reversals. Examples of numerically integrated trajectories in both static (zero electric field) and time dependent (corresponding nonzero induction electric field) simple models for magnetic reversals are considered. In the static case, the dynamics can in principle be directly classified by constructing Poincaré surfaces of section; here we demonstrate that whilst the Poincaré surface contains the relevant information to classify the dynamics, the corresponding delay coordinate plot can provide a far more sensitive indication of the onset of nonregular behaviour. In the case of nonperiodic time dependence considered here Poincaré plots cannot in general be constructed directly. Nevertheless, delay coordinate plots can still reveal details of the phase space portrait of the system, and here are shown to indicate whether segments of stochastic motion exist in a given trajectory. It is anticipated that the delay coordinate plot technique as realized here will be a valuable tool in characterizing the behaviour in large numbers of trajectories that are evolved in time-dependent systems, thereby giving us insight into the evolution of the distribution function as a whole, either in prescribed fields or in self-consistent numerical simulations.
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