93 research outputs found

    Limit cycles bifurcating from a family of reversible quadratic centers via averaging theory

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    Consider the class of reversible quadratic systems x· = y, y· = -x + x²+ y² - r², with r > 0. These quadratic polynomial differential systems have a center at the point ((1 -√(1+4r²)/2, 0) and the circle x² + y² = r² is one of the periodic orbits surrounding this center. These systems can be written into the form x· = y + (4 + A)x² - Ay², y· = -x, with A ϵ (-2, 0). For all A ϵ R we prove that the averaging theory up to seventh order applied to this last system perturbed inside the whole class of quadratic polynomial differential systems can produce at most two limit cycles bifurcating from the periodic orbits surrounding the center (0,0) of that system. Up to now this result was only known for A = -2 (see [22, 23])

    Anti-angiogenesis effect of <em>crocous sativus </em>L. extract on matrix metalloproteinase gene activities in human breast carcinoma cells

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    Introduction: There is an interest in Crocous sativus L. (Saffron) mainly because of its biological properties. Biomedical research has focused on saffron as a powerful antioxidant, anti-inflammatory and anti-tumor, but its mechanism has not yet been thoroughly clarified. In this study, the effects of saffron aqua extract on matrix metalloproteinases (MMP) gene expression were investigated. Methods: In this experimental study, the saffron was extracted using water as solvent. MCF-7 cells in RPMI1640 medium were supplemented with 10 FBS and incubated at 37 ˚C with 5 CO2. After 24 h, the cells were treated by saffron extract at concentrations of 100, 200, 400 and 800 &mu;g/ml. 48 h after treatment, total RNA was extracted and cDNA was synthesized using specific primer. Synthesized products were analyzed by Real Time PCR to determine expression level of MMP. Results: Data analysis showed inhibitory effect of saffron at concentrations of 100 to 800 &mu;g/ml on MMP gene expression in comparison with control group. Reduction for 100, 200, 400 and 800 &mu;g/ml were 5, 18, 15, 11, respectively. According to data analysis treating MCF-7 cells with saffron at concentration of 200 &mu;g/ml caused the highest decrease, with 18 reduction in gene expression (P&lt;0.001). Conclusion: Results indicate decrease in the expression of MMP compared with controls revealing induction of inhibitory effects of saffron on angiogenesis which might be also considered as a promising chemotherapeutic agent in breast cancer treatment.</p

    Synergistic effect of pulsed electromagnetic fields and saffron extract on osteogenic differentiation of bone marrow mesenchymal stem cells

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    Introduction: Pulsed electromagnetic fields (PEMFs) are usually used to treat non-union fractures. Saffron is a medicinal plant with various pharmacologic effects. In the present study, the synergistic effect of PEMF and saffron aqueous extract on osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) was evaluatedMethods: BMSCs were isolated from rat femur. After purification, the cells were divided into four groups including control group (did not receive any treatment), saffron alone (800 &mu;g/mL), PEMF alone (50 Hz, 3 times a weak, 2 hours for every time, for 2 weeks), and saffron plus PEMF. Cytotoxicity was measured using MTT assay. After calculating the IC50 value for saffron extract (1.5 mg/mL), a lower concentration (800 &mu;g/mL) was combined with PEMF. The differentiation of each cell group was evaluated using alkaline phosphatase (ALP) enzyme activity, alizarin red staining and reverse transcribed polymerase chain reaction (RT-PCR) method.Results: Saffron aqueous extract decreased dose-dependently the cell viability but the PEMF had not any significant effects on cell viability. The PEMF, saffron extract and their combination increased the ALP activity on day 10 but the increase was significant in synergist group. Alizarin red staining showed that mineralization groups were higher at day 14. RT-PCR results demonstrated that on the day 14 the group treated with both PEMF and saffron expressed osteogenic genes.Conclusion: Saffron extract combined with PEMFs could promote osteogenesis at the initial stage (the commitment of undifferentiated mesenchymal stem cells into osteoblast), hence, its usage might be beneficial in these patient

    Heterocyclic aromatic amines in doner kebab : quantitation using an efficient microextraction technique coupled with reversed-phase high-performance liquid chromatography

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    The safety of doner kebab as a traditional Middle East tasty food can threaten via the formation of dangerous compounds such as heterocyclic aromatic amines during heat process. In this regard, the current investigation was devoted to measuring of 4 HAAs (2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), and 2-amino-3-methylimidazo[4,5-f]quinoline (IQ)) in doner kebab samples with an innovative microextraction technique combined with high-performance liquid chromatography. The limit of detection was in the range of 4.8 and 5.3 ng/g, while relative standard deviations were between 6.5% and 8.3%, and recoveries were calculated in the range of 89%-97%. The most and the least total mean values of HAA levels were 13.30 ng/g for MeIQx and 5.0 ng/g for IQ. The proposed method showed a high capability to extract trace amount of HAAs from a complex matrix such as doner kebab. Also, this technique is easy, high sensitive, selective, accurate and efficient81889

    Anti-angiogenesis effect of biogenic silver nanoparticles synthesized using Saliva officinalis on chick chorioalantoic membrane (CAM)

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    Angiogenesis, which is required for physiological events, plays a crucial role in several pathological conditions, such as tumor growth and metastasis. The use of plant extracts is a cost effective and eco-friendly way to synthesize nanoparticles. In the present study, we investigated the anti-angiogenesis properties of silver nanoparticles synthesized using Saliva officinalis extract on chick chorioalantoic membrane. The production of nanoparticles was confirmed by the color change from yellow to brown observed after approximately 3 h at 37 °C. Then, the nanoparticles were characterized by UV-visible spectroscopy, FTIR, and TEM. The UV-visible spectroscopy results showed that the surface plasmon resonance band for AgNPs was around 430 nm. The intensity of the AgNP-specific absorption peak improved with an increase of 0.5 mL of extract into 10 mL of AgNO3 (2.5 mM). The FTIR results showed good interaction between the plant extracts and AgNPs. The TEM images of the samples revealed that the NPs varied in morphology and size from 1 to 40 nm; the average was recorded at 16.5 ± 1.2 nm. Forty Ross fertilized eggs were divided into four groups; the control and three experimental groups. On the 8th day, gelatin sponges containing albumin were placed on the chorioalantoic membrane and soaked with different concentrations of NPs. On the 12th day, all the cases were photographed using a photostereomicroscope. The number and the lengths of the vessels were measured using Image J software. The crown rump (CR) and weight of the embryo were also recorded. Then the hemoglobin content was measured using Drabkin’s reagent kit for quantification of the blood vessel formation. According to the data analysis, the number and length of the blood vessels, as well as the CR and weight of the embryos reduced significantly compared to the control (p < 0.05), dose dependently. The total hemoglobin was quantified as an indicator of the blood vessel formation. The hemoglobin content in the treated samples with AgNPs decreased, which showed its inhibitory effect on angiogenesis

    The synergic effects of Saffron aqua extract and low frequency electromagnetic field on angiogenesis in chick chorioalantoic membrane

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    زمینه و هدف: مطالعات in vivo وin vitro بر اثرات ضد سرطانی زعفران تاکید دارند. آنژیوژنز برای تکوین جنین و بسیاری از وقایع فیزیولوژیکی و پاتولوژیک نظیر رشد تومورها، ضروری است. همچنین بسیاری از فرایندهای رشد و نمو تحت تاثیر میدان‌های الکترومغناطیسی قرار می‌گیرند. این مطالعه با هدف بررسی اثرات توام عصاره زعفران و میدان ‌‌الکترومغناطیسی با فرکانس پایین برآنژیوژنز طراحی شد. روش بررسی: در این پژوهش تجربی آزمایشگاهی تخم ‌مرغ های نطفه‌دار در 9 گروه شامل گروه‌های شاهد و شاهد آزمایشگاهی1 و 2، گروه‌های تجربی 1، 2 و 3 (تیمار با عصاره زعفران با غلظت های 100، 400 و 800 g/mlµ) و گروه‌های تجربی 4، 5 و 6 (تیمار توام عصاره زعفران همراه میدان‌الکترومغناطیسی 400 گاؤس) بصورت تصادفی تقسیم شدند. در روز دوم انکوباسیون، در شرایط استریل قسمتی از پوسته تخم‌مرغ‌ها برداشته شد و پنجره ای باز ایجاد گردید. در روز هشتم 10 میکرولیتر از غلظت های مختلف عصاره به نمونه ها تیمار گردید. در روز دهم تخم‌مرغ‌ها 4 ساعت در معرض میدان ‌الکترومغناطیسی (فرکانس 50 هرتز و شدت 400 گاؤس) قرارگرفتند. در روز دوازدهم از تمامی نمونه‌ها به کمک فتواسترئومیکروسکوپ عکس تهیه و تعداد و طول انشعابات عروقی محل تیمار روی پرده کوریوآلانتوئیک به کمک نرم‌افزارImage J بررسی گردید. نتایج با استفاده از آزمون های آماری ANOVA و تست تعقیبی Tukey تحلیل شدند. یافته ها: میانگین طول عروق خونی در گروه تجربی 1 نسبت به گروه شاهد کاهش معنی داری نشان نداد (05/0P>) در حالی که در گروه‌های تجربی 2 و 3 کاهش معنی داری مشاهده شد (001/0

    New Family of Centers of Planar Polynomial Differential Systems of Arbitrary Even Degree

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    The problem of distinguishing between a focus and a center is one of the classical problems in the qualitative theory of planar differential systems. In this paper, we provide a new family of centers of polynomial differential systems of arbitrary even degree. Moreover, we classify the global phase portraits in the Poincaré disc of the centers of this family having degree 2, 4, and 6

    Importance-Performance Analysis (IPA) on Factors Affecting Agility of Iranian Auditing Organizations

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    Many auditors are now encountering agile management methodologies for the first time. In some cases, this can cause problems for the audit process because the methodology is very different from traditional approaches. Aside from the difficulties faced by the auditor, an ineffective audit can have a negative effect on an agile project by giving a false impression of its progress. Much has been written on agility issues in organizations of various sizes. However, there have been very few studies that attempt to delineate critical issues that drive importance-performance analyzing (IPA) among an organization. This paper aims to propose an Importance-Performance Analysis (IPA) on Factors Affecting Agility of Iranian Auditing Organizations

    Anti-angiogenesis effect of crocous sativus L. extract on matrix metalloproteinase gene activities in human breast carcinoma cells

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    Introduction: There is an interest in Crocous sativus L. (Saffron) mainly because of its biological properties. Biomedical research has focused on saffron as a powerful antioxidant, anti-inflammatory and anti-tumor, but its mechanism has not yet been thoroughly clarified. In this study, the effects of saffron aqua extract on matrix metalloproteinases (MMP) gene expression were investigated. Methods: In this experimental study, the saffron was extracted using water as solvent. MCF-7 cells in RPMI1640 medium were supplemented with 10% FBS and incubated at 37 ˚C with 5% CO2. After 24 h, the cells were treated by saffron extract at concentrations of 100, 200, 400 and 800 μg/ml. 48 h after treatment, total RNA was extracted and cDNA was synthesized using specific primer. Synthesized products were analyzed by Real Time PCR to determine expression level of MMP. Results: Data analysis showed inhibitory effect of saffron at concentrations of 100 to 800 μg/ml on MMP gene expression in comparison with control group. Reduction for 100, 200, 400 and 800 μg/ml were 5%, 18%, 15%, 11%, respectively. According to data analysis treating MCF-7 cells with saffron at concentration of 200 μg/ml caused the highest decrease, with 18% reduction in gene expression (P<0.001). Conclusion: Results indicate decrease in the expression of MMP compared with controls revealing induction of inhibitory effects of saffron on angiogenesis which might be also considered as a promising chemotherapeutic agent in breast cancer treatment

    Medical error and under-reporting causes from the viewpoints of nursing managers : a qualitative study

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    Background: Patient safety as a goal can be achieved by reporting medical errors (ME); however, most errors are never reported. The aim of this study is to explore the causes of ME, and the obstacles in reporting them amongst nurses. Methods: We conducted semi-structural interviews, with 12 nursing managers in the biggest teaching hospital in southern Iran (2015-2016). The interview guide concentrated on the causes of ME and barriers in reporting them. All face-to-face interviews were recorded and transcribed verbatim and analysed using thematic analysis. Results: In this study 4 main themes were extracted for the causes of ME: personal/social characteristics, nonprofessional practice, hospital related factors/organization contextual factors, and poor management. Also, 5 main themes (such as; personal characteristics, fear from reporting, nonprofessional practices, cultural and social factors, and error surveillance system features) were obtained with regards to barriers in reporting. Conclusions: ME can be reduced by improving professional practice and better human resource management. Also, reporting errors can be increased by focusing on cultural and social factors
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