bluuebunny/crossref_metadata_2025 huggingface dataset:
Poster — Thur Eve — 60: Physical and dynamic wedges in radiotherapy for rectal cancer: A dosimetric comparison
Authors: Isa M , Iqbal K , Afzal M , Buzdar S , Chow J
Published: July 2012

The aim of this study is to compare the dosimetry of the physical wedge (PW) and enhanced dynamic wedge (EDW) in radiotherapy of rectal cancer. Two wedge angles of 45° and 60° were used in the comparison due to the size of the pelvis contour. 6 and 15 MV photon beams produced from a Varian 21 CD linear accelerator were used. Thirty rectum patients were investigated using the three‐field technique. Treatment plans using the PWs and EDWs were created using the Eclipse treatment planning system. Monitor units, plan normalization value, maximum and minimum doses in the planning target volume (PTV), dose conformity index, dose homogeneity index and uniformity index were determined for each treatment plan. The average dose coverage for the PTV with EDW and PW plans were compared. The PTV received prescription doses of 100.9±0.74%, 101.01±1.63% for the EDW (45°, 60°) compared to 101.2±1.65%, 101.3±1.33% for the PW (45°, 60°). Homogeneity indices were (0.11±0.02%, 0.11±0.05%) for the EDW (45°, 60°), and (0.15±0.1%, 0.16±0.11%) for the PW (45°, 60°), respectively. The EDW at 45° had better target coverage with higher conformity index value of 0.98 ± 0.01 compared to the other wedges. A statistically significant (p < 0.01) change in plan normalization values and fewer monitor units were found using the EDW at 45°. We conclude that the EDW at 45° results in an improvement to the plan evaluation parameters presented and thus increases dose efficacy for radiotherapy of rectal cancer.
Poster — Thur Eve — 62: Assessing the clinical application of the van Herk margin formula for lung radiotherapy
Authors: Ecclestone G , Heath E , Bissonnette J‐P
Published: July 2012

According to a margin recipe developed by van Herk et al. the Planning Target Volume (PTV) margin to ensure the Clinical Target Volume is covered by at least 95% of the prescribed dose can be calculated by applying the following formula: . In the van Herk Margin formula (VHMF), Σ is the standard deviation (SD) of all systematic errors; σ is the SD of random errors and σp is the width of the penumbra. This formula is based on an idealized dose profile model that may not account for factors that vary significantly in lung radiotherapy such as tumour size and tissue density. The purpose of this study was to use accurate dose calculation algorithms and respiratory motion modeling to investigate the validity of the VHMF for lung radiotherapy. Random and systematic errors were simulated in treatment planning software using dose accumulation techniques for clinically relevant 3DCRT and IMRT treatment plans constructed on virtual phantoms. Phantom parameters such as target size, peak‐to‐peak motion amplitude and tissue density were varied to investigate their impact on the systematic and random error components of the margin formula. The VHMF was found to provide adequate dose coverage for all plans generated on different target sizes and motion amplitudes. Although discrepancies existed between idealized and realistic dose profiles in water and lung, the dose coverage defined by the V95 was not affected. The margin formula was found to be robust; however, further investigation of the influence of plan conformity is needed.
Poster — Thur Eve — 63: Dosimetric impact of breathing motion in lung SBRT: Dual vs single volumetric modulated arc therapy
Authors: El‐Sherif O , Xhaferllari I , Johnson C , Chen J , Gaede S
Published: July 2012

Volumetric modulated arc therapy (VMAT) is a time efficient treatment delivery platform capable of producing highly conformal dose distributions with a single 360° arc. However, additional arcs can be used to further improve the conformal dose distribution. For these reasons, VMAT is often used for stereotactic body radiation therapy (SBRT) in which the treatment deliveries are hypofractionated. The dosimetric impact of tumour motion, especially in lung SBRT where tumour motion is most significant and treatments are hypofractionated, has always been a clinical concern. Through the use of 4‐dimensional computed tomography (4D‐CT), 4D dose distributions can be calculated that account for dosimetric errors due to motion and temporal variation in lung density that are not accounted for in clinical treatment plans. The purpose of this study was to quantify the dosimetric differences that arise due to tumour motion and variations in lung density between single and dual VMAT SBRT treatment plans. Six patients previously treated for stage I/II non‐small‐cell lung cancer with SBRT were included in this retrospective study. 3D and 4D dose distributions were calculated for both single and dual arc plans for each of the six patients. Dose‐volume histogram metrics are reported for the target and critical structures. The results show significant differences (p ≤ 0.05) between the 3D and 4D dose distributions for the ratio of the prescription isodose volume to the primary target volume (PTV). This result was consistent for both single and dual arc VMAT plans.
Poster — Thur Eve — 64: Evaluation of SmartArc and RapidArc for lung SBRT treatment planning and delivery
Authors: Fakir H , Hoover D , Chen JZ
Published: July 2012

Objectives: To evaluate the performance of RapidArc® (Eclipse 10.0.28) and SmartArc® (Pinnacle 9.0) radiotherapy plans for lung stereotactic body radiation therapy (SBRT) in terms of dosimetric plan quality, delivery efficiency, inhomogeneity corrections and accuracy of dose delivery using a custom‐built heterogeneity insert for ArcCHECK™ (Sun Nuclear Corp., FL, USA). Methods: SmartArc® and RapidArc® plans were generated for 10 patients. The quality of the plans was evaluated in terms of conformity indices (R100 and R50) and the dose to the organs at risk. The efficiency was evaluated in terms of the monitor units (MUs) required for a given prescription dose. For dose verification, we designed and manufactured a heterogeneity insert for ArcCHECK™ with densities that simulate soft tissue, lung, bone, and air and having multiple locations for point dose measurements. Accuracy of dose delivery was assessed using gamma analysis. Results: The overall plan quality was similar when comparing SmartArc® with RapidArc®. However, RapidArc® plans required significantly more MUs—up to 72%™compared with SmartArc® plans (p<0.001). ArcCHECK™ measurements in the presence of inhomogeneities showed better agreement for SmartArc® plans. Conclusion: Plan quality for SmartArc® and RapidArc® was comparable. However, SmartArc® plans were more efficient, requiring significantly fewer monitor units, and were delivered more accurately in a non‐homogeneous phantom. With the custom‐built heterogeneity insert, ArcCHECK™ can be used efficiently to verify inhomogeneity corrections and dose delivery accuracy for lung SBRT plans.
Poster — Thur Eve — 68: Evaluation and analytical comparison of different 2D and 3D treatment planning systems using dosimetry in anthropomorphic phantom
Authors: Khosravi HR , Nodehi MR Golrokh , Asnaashari Kh , Mahdavi SR , Shirazi AR , Gholami S
Published: July 2012

Purpose: The aim of this study was to evaluate and analytically compare different calculation algorithms applied in our country radiotherapy centers base on the methodology developed by IAEA for treatment planning systems (TPS) commissioning (IAEA TEC‐DOC 1583). Material & Methods: Thorax anthropomorphic phantom (002LFC CIRS inc.), was used to measure 7 tests that simulate the whole chain of external beam TPS. The dose were measured with ion chambers and the deviation between measured and TPS calculated dose was reported. This methodology, which employs the same phantom and the same setup test cases, was tested in 4 different hospitals which were using 5 different algorithms/ inhomogeneity correction methods implemented in different TPS. The algorithms in this study were divided into two groups including correction based and model based algorithms. Results: A total of 84 clinical test case datasets for different energies and calculation algorithms were produced, which amounts of differences in inhomogeneity points with low density (lung) and high density (bone) was decreased meaningfully with advanced algorithms. The number of deviations outside agreement criteria was increased with the beam energy and decreased with advancement of the TPS calculation algorithm. Conclusion: Large deviations were seen in some correction based algorithms, so sophisticated algorithms, would be preferred in clinical practices, especially for calculation in inhomogeneous media. Use of model based algorithms with lateral transport calculation, is recommended. Some systematic errors which were revealed during this study, is showing necessity of performing periodic audits on TPS in radiotherapy centers.
Poster — Thur Eve — 71: Improved dose accuracy for plan checking IMRT breast plans
Authors: Corns R , Thomas S , Dubrowski P , Huang V , Shahine L
Published: July 2012

Dose verification as part of plan checking is a critical component of high quality patient care. IMSure QA is a software platform used at the BC Cancer Agency that facilitates dose verification for both conformal and IMRT plans. We have recently initiated treating breast tangents using IMRT at the Fraser Valley Centre and noted increased dose discrepancies (mean difference of −3%) between Eclipse and IMSure's QA module. We identified two potential sources of error: air flash and tissue heterogeneity. We extend our generated fluences 3cm past the breast contour and into air to account for breathing, set‐up uncertainties and swelling. IMSure does not account for the fluence in air or air flash. We present an air‐flash‐correction factor based on the ratios of TMRs and Phantom Scatter Factors which use the field sizes of fields with and without the air flash. In addition, we present a method to improve the heterogeneity correction used by IMSure to better match that used by AAA. Effectively we remove the IMSure's inherent heterogeneity correction and manually apply a AAA‐based heterogeneity‐correction factor. We evaluated our correction factors on a sample of 8 patients (32 fields) using ANOVA methods to determine which dose corrections most accurately reproduce Eclipse's values. We found the air‐flash correction coupled with IMSure's inherent‐heterogeneity correction has the best dose accuracy (mean difference improved from −3% to 0.3%). The AAA‐heterogeneity correction alone also improved the accuracy (mean difference improved from −3% to − 1.5%), which is acceptable for plan checking purposes.
Poster — Thur Eve — 73: Prediction of risks of cardiac mortality and secondary cancers after radiotherapy for Hodgkin's lymphoma, non‐Hodgkin's lymphoma, and breast cancer
Authors: Toltz A , Shin N , Laude C , Roberge D , Freeman C , Seuntjens J , Parker W
Published: July 2012

Purpose: To predict the risks of late, radiation‐induced effects for young patients with Hodgkin's lymphoma (HL), non‐Hodgkin's lymphoma (NHL), or breast cancer (BC) if treated with intensity modulated proton therapy (IMPT) compared to 3D conformal photon radiotherapy (3D‐CRT). Late effects considered were cardiac mortality and secondary cancer in the lungs and breasts (for female patients). Methods: Patient data were acquired for twenty‐six patients (ages 12–29) who were treated with 3D‐CRT for HL, NHL, or BC in 2010. Original CT simulation images were used to re‐plan the patients with IMPT using commercially‐available treatment planning software. The contours of the organs at risk were reviewed by a single physician and modified for consistency. The dose‐volume data of the 3D‐CRT plans and the new IMPT plans were analyzed to model the risks of late effects. The relative seriality model was used to predict excess risk of cardiac mortality at fifteen years post‐irradiation. A modified linear quadratic model was used to predict the Excess Absolute Risk (EAR) for induction of lung cancer and breast cancer at thirty years post‐irradiation. Results: For 3D‐CRT and IMPT respectively, the mean excess risks of cardiac mortality were 0.9% and 0.5%. Mean EARs for lung cancer were 17.5 cases per 10,000 persons per year (PY) and 10.1 PY. Mean EARs for breast cancer were 8.2 PY and 2.8 PY. Conclusions: IMPT may significantly reduce the risks of radiation‐induced cardiac mortality and secondary cancer in the lungs and breasts of young patients receiving radiotherapy for HL, NHL, or breast cancer.
Poster — Thur Eve — 77: Coordinate transformation from DICOM to DOSXYZnrc
Authors: Zhan L , Jiang R , Osei EK
Published: July 2012

DICOM format is the de facto standard for communications between therapeutic and diagnostic modalities. A plan generated by a treatment planning system (TPS) is often exported to DICOM format. BEAMnrc/DOSXYZnrc is a widely used Monte Carlo (MC) package for beam and dose simulations in radiotherapy. It has its own definition for beam orientation, which is not in compliance with the one defined in DICOM standard. Dose simulations using TPS generated plans require transformation of beam orientations to DOSXYZnrc coordinate system (c.s.) after extracting the necessary parameters from DICOM RP files. The transformation is nontrivial. There have been two studies for the coordinate transformations. The transformation equation sets derived have been helpful to BEAMnrc/DOSXYZnrc users. However, both the transformation equation sets are complex mathematically and not easy to program. In this study, we derive a new set of transformation equations, which are more compact, better understandable, and easier for computational implementation. The derivation of polar angle θ and azimuthal angle φ is similar to the existing studies by applying a series of rotations to a vector in DICOM patient c.s. The derivation of beam rotation Φcol for DOSXYZnrc, however, is different. It is obtained by a direct combination of the actual collimator rotation with the projection of the couch rotation to the collimator rotating plane. Verification of the transformation has been performed using clinical plans created with Eclipse. The comparison between Eclipse and MC results show exact geometrical agreement for field placements, together with good agreement in dose distributions.
Sci—Fri AM: Imaging — 02: High resolution detectors for PET mammography
Authors: Cuddy SG , Rowlands JA
Published: July 2012

Purpose: With high specificity for malignant breast lesions, dedicated‐breast molecular imaging systems such as positron emission mammography (PEM) have potential to improve the sensitivity of cancer in women with radio‐dense breasts and to reduce the false‐positive rate of breast screening when used as a diagnostic adjunct. For high signal‐to‐noise ratio and to minimize the patient dose, scintillation detectors in a PEM system must have high annihilation photon detection efficiency. This efficiency can be increased by accepting annihilation photons from wider incident angles and by using depth‐of‐interaction (DOI) measurement within a scintillation crystal to minimize parallax blurring. We have developed a dual‐ended readout block (DERB) detector that uses asymmetry of signals from photodetectors on either end of a scintillation array to measure DOI and uses Anger Logic with light sharing to identify interacting crystal elements while minimizing the number of photodetectors required. Methods: A prototype DERB detector was constructed from two arrays of silicon photomultipliers (SiPM), two glass optical diffusers, and an array of LYSO scintillation crystals. Assembled, each of the 2 × 2 SiPM arrays detect photons that are dispersed via the optical light diffusers originating from either end of 3 × 3 scintillation crystal elements. We evaluated the ability of the detector to identify the crystal index, resolve DOI, and discriminate energy. Results: The DERB detector was able to clearly identify interacting crystal elements, to measure DOI with ̃5mm resolution in 2mm × 2mm × 20mm crystals, and to achieve an average energy resolution of ̃20%. Conclusions: The DERB detector characteristics suggest that it can be used to reduce the parallax effect in PEM systems without increasing the number of required photodetectors. Further investigation is warranted to improve performance with high optical photon detection efficiency photodetectors.
Sci—Fri PM: Delivery — 01: Approach to evaluate the accuracy of individual control‐points of a VMAT delivery measured by an EPID
Authors: Asuni G , Popescu T , McCurdy B
Published: July 2012

A unique approach that uses Monte Carlo (MC) methods to validate time‐resolved measured dose by an electronic portal imaging device (EPID) during delivery of volumetric modulated arc therapy (VMAT) treatments was investigated. Time‐resolved dose is simultaneously scored in both the patient and EPID geometries. A RapidArc© verification plan was generated and delivered on a homogeneous cylindrical phantom. Portal images were collected using an aS1000 amorphous‐silicon EPID attached to a Varian Clinac 2100ix. The images were acquired in the continuous acquisition mode and in‐house analysis software was used to obtain images for each control point. We performed MC simulation and dose calculation of the verification plan using the EGSnrc MC package. The MC phantom file contains both the EPID model and the cylindrical phantom derived from the CT data sets. For the individual control point simulation, we rotate the phantom only using the gantry angle information. For this work, we calculated dose distributions for five control points (out of a total of 177) in the verification plan. The normalized measured and calculated data were compared using the chi comparison (computationally efficient implementation of gamma). The chi comparison between measured and calculated doses for the five control points using criteria of 3% and 3mm revealed an average of 88.7% of all pixels having χ<1. The agreement will improve when the measured portal images are corrected for flood field and support‐arm backscatter effects. This approach allows us to obtain both the EPID dose and the phantom/patient dose. These preliminary results demonstrate promising accuracy. With further improvements, this approach will be useful for benchmarking of time‐resolved EPID dose applications intended for rotational IMRT QA and adaptive radiation therapy.
Sci—Fri PM: Delivery — 04: Quantitative air communication testing of ion chambers for megavoltage dosimetry
Authors: McEwen M , Gamal I El
Published: July 2012

The valid application of the standard correction for air density (PTP in the TG‐51 protocol) requires that for a vented ion chamber (basically all reference‐class ion chambers) the air cavity does indeed communicate directly with the external environment. However, this assumption is not tested by users, and not universally verified by calibration laboratories. A system has therefore been developed at the National Research Council to test air communication of cylindrical and parallel‐plate ion chambers. The systems is based on measurements in a vacuum vessel with a Sr‐90 check source; the procedure is simple and quick and can measure ionization currents over the pressure range 0 kPa (atmospheric) to −20kPa (0.8 atm) with an uncertainty better than 0.2%. Investigation of a wide range of chamber types shows that for a coarse check on chamber performance (i.e., that the chamber is vented to atmosphere) measurement at a single polarity is sufficient (total test time less than 15 minutes) but for accurate characterization of the chamber performance, data at both polarities must be acquired. The accuracy of the system means that it can potentially be used to investigate: i) the validity of the pressure correction, and ii) the source of the polarity correction in cylindrical and parallel‐plate chambers. The air communication test will be implemented as part of the standard calibration services provided by NRC for external beam radiotherapy.
Sci—Fri PM: Delivery — 11: Accuracy considerations in modern radiation oncology: An update
Authors: Van Dyk J , Battista JJ , Bauman GS
Published: July 2012

The most recent reviews of accuracy requirements in radiation oncology were published in the 1990s, primarily in an era that was transitioning from 2‐D to 3‐D conformal radiation therapy (CRT). Since then, the technology associated with radiation oncology has changed dramatically. The combination of various forms of imaging for radiation therapy planning, treatment planning software, dose delivery technology including 4‐D considerations as well as in‐room daily image guidance has resulted in new perspectives on accuracy considerations. The underlying hypothesis for the use of these advanced technologies is that loco‐regional control of cancer remains a significant barrier to cancer cure for many common cancers and that better dose distributions will translate into better outcomes. However, further clinical gain using these new technologies may be limited by single or compounded uncertainties associated with the entire treatment process. Thus, it is important to understand what factors should be considered in determining accuracy requirements as well as the realistic expectations of uncertainties that exist within the total treatment process. The need for accuracy is based on clinical requirements such as the steepness of dose‐response curves, inherent heterogeneity in patient response to treatment, and the level of accuracy that is practically achievable. Statements on accuracy are dependent on the technology used and the reality of what is practically achievable and necessary. This review highlights some of the major differences between accuracy requirements as determined in the 2‐D RT and 3‐D CRT era versus the modern era of intensity modulated, image‐guided, 4‐D radiation therapy.
Sci—Sat AM: Brachy — 11: Improving treatment planning for I‐125 lung brachytherapy using Monte Carlo methods
Authors: Sutherland JGH , Furutani KM , Thomson RM
Published: July 2012

125I brachytherapy used in conjunction with sublobar resection to treat stage I non‐small cell lung cancer has been reported to improve disease‐free and overall survival rates compared with resection alone. Treatments are planned intra‐operatively using seed spacing nomograms or tables to achieve a prescription dose defined 5 mm above the implant plane. Dose distributions for patients treated with this technique at the Mayo Clinic Rochester were reanalyzed using a Monte Carlo (MC) calculation; significant differences were observed between the standard TG‐43 dose calculations and the actual dose delivered as determined by MC. This work investigates differences between TG‐43 calculated prescription doses and those calculated in more accurate models. Monte Carlo calculations are performed using the EGSnrc user‐code BrachyDose with a number of lung tissue phantom models including patient CT‐derived phantoms. Seed spacing nomograms using these models are recalculated by determining the dose to the prescription point using the activities per seed required to produce a prescription dose of 100 Gy with the TG‐43 point source formalism. Models using nominal density lung or CT‐derived density lung tissue result in a significant increase in dose to the prescription point (up to approximately 25%) compared to TG‐43 calculated doses. The differences observed suggest that patients routinely receive significantly higher doses than planned using TG‐43 derived nomograms. Additionally, deviation from TG‐43 increases as seed spacing increases. Media heterogeneities significantly affect dose distributions and prescription doses for 125I lung brachytherapy, underlining the importance of using model‐based dose calculation algorithms to plan and analyze these treatments.
Speech enhancement using a generic noise codebook
Authors: Srinivasan Sriram , Rao Naidu D. Hanumantha
Published: July 2012

Although single-microphone noise reduction methods perform well in stationary noise environments, their performance in non-stationary conditions remains unsatisfactory. Use of prior knowledge about speech and noise power spectral densities in the form of trained codebooks has been previously shown to address this limitation. While it is possible to use trained speech codebooks in a practical system, the variety of noise types encountered in practice makes the use of trained noise codebooks less practical. This letter presents a method that uses a generic noise codebook for speech enhancement that can be generated on-the-fly and provides good performance.
Carvedilol suppresses fatty acid oxidation and stimulates glycolysis in C2C12 cells
Authors: Onay-Besikci Arzu , Suzmecelik Elif , Ozcelikay A. Tanju
Published: July 2012

Beta adrenergic receptor blocking drugs (β-blockers) are used chronically in many cardiovascular diseases such as hypertension, ischemic heart disease, arrhythmia, and heart failure. Beneficial effects are associated with the inhibition of symphathetic nervous system hyperactivity, reduction of heart rate, and remodeling by blocking the mitogenic activity of catecholamines. A possible effect of β-blockers on substrate metabolism has also been suggested. The direct effects of β-blockers on mouse C2C12 cells were investigated in this study. C2C12 cells were grown in Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 10% fetal bovine serum (FBS) and differentiated into myotubes in the same medium that contained 1% FBS. Palmitic acid oxidation and glycolysis were measured by using [9,10-3H]palmitate and [5-3H]glucose, respectively. The amount of3H2O was measured as an indicator of substrate usage. Carvedilol (100 µmol/L) inhibited palmitate oxidation and increased glycolysis by nearly 50%. Prazosin altered substrate metabolism in a similar fashion as carvedilol, whereas propranolol or bisoprolol were devoid of metabolic effects. When added to mimic sympathetic activation, epinephrine stimulated glycolysis but did not alter fatty acid oxidation. Based on these results, carvedilol appears to have direct effects on substrate metabolism that are related to the blockade of α1 adrenergic receptors.
The EGFR tyrosine kinase inhibitor tyrphostin AG-1478 causes hypomagnesemia and cardiac dysfunction
Authors: Weglicki William B. , Kramer Jay H. , Spurney Christopher F. , Chmielinska Joanna J. , Mak I. Tong
Published: July 2012

We determined whether the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) N-​(3-​chlorophenyl)-​6,​7-​dimethoxy-​4-​quinazolinamine (tyrphostin AG-1478) causes hypomagnesemia and cardiac dysfunction in rats. Tyrphostin was administered (3 times per week, intraperitoneal injection, to achieve 21.4 mg·(kg body mass)–1·day–1) to normomagnesemic rats for 5 weeks. Levels of magnesium in the plasma of the tyrphostin-treated rats decreased significantly by the following amount: 17% at week 1, 27% at week 2, and 26%–35% between weeks 3 to 5. Levels of the plasma lipid peroxidation marker 8-isoprostane rose significantly: by 58% at week 1, 168% at week 3, and 113% at week 5. At week 5, blood neutrophils from the tyrphostin-treated group displayed a 2.26-fold higher basal level of [Formula: see text] generation; the ratio of oxidized glutathione (glutathione disufide; GSSG) to reduced glutathione (GSH) in the red blood cells increased 2.5-fold. At week 5, echocardiography revealed that TKI treatment resulted in significant cardiac systolic dysfunction, with impaired diastolic function and dilated cardiomyopathy. Since hypomagnesemia alone can trigger oxidative stress and cardiac injury, we suggest that inhibition of EGFR–TK caused magnesium wasting, which partly contributed to decreased cardiac contractility.
Antioxidant characterization of soy derived products in vitro and the effect of a soy diet on peripheral markers of oxidative stress in a heart disease model
Authors: Hagen Martine Kienzle , Ludke Ana , Araujo Alex Sander , Mendes Roberta Hack , Fernandes Tânia Gatelli , Mandarino Jose Marcos Gontijo , Llesuy Susana , Vogt de Jong Erna , Belló-Klein Adriane
Published: July 2012

This study analyzed and compared the content of isoflavones in 2 soy products, the effectiveness of isoflavones as antioxidants, in vitro, and demonstrated the antioxidant effect of a soy diet in rats with myocardial infarction (MI). Isoflavone content was analyzed in soybean hypocotyl (SH) and isolated soy protein (ISP). The quality (TAR) and quantity (TRAP) of antioxidants present in the samples was quantified. The amount of daidzin was higher in SH (9 times) and genistein in ISP (5 times). SH presented a 3-fold increase in TAR, while both products exhibited same TRAP. The rats were fed an ISP diet for 9 weeks. Animals were distributed among 6 treatment groups: (i) Sham Casein; (ii) Infarct Casein < 25%; (iii) Infarct Casein > 25%; (iv) Sham Soy; (v) Infarct Soy < 25%; and (vi) Infarct Soy > 25%. MI was induced 5 weeks after the commencement of the diets. Lipid peroxidation (LPO), antioxidant enzyme activity, and levels of nitrites/nitrates were determined in blood. Rats receiving the ISP diet demonstrated increased activity of antioxidant enzyme activity and nitrite/nitrate content. In addition, the increase in LPO seen in rats subjected to MI was significantly mitigated when the ISP diet was given. These findings suggest a nutritional approach of using a soy-based diet for the prevention of oxidative-stress-related diseases such as heart failure.
Implications of protease activation in cardiac dysfunction and development of genetic cardiomyopathy in hamsters
Authors: Müller Alison L. , Freed Darren , Hryshko Larry , Dhalla Naranjan S.
Published: July 2012

It has become evident that protein degradation by proteolytic enzymes, known as proteases, is partly responsible for cardiovascular dysfunction in various types of heart disease. Both extracellular and intracellular alterations in proteolytic activities are invariably seen in heart failure associated with hypertrophic cardiomyopathy, dilated cardiomyopathy, hypertensive cardiomyopathy, diabetic cardiomyopathy, and ischemic cardiomyopathy. Genetic cardiomyopathy displayed in different strains of hamsters provides a useful model for studying heart failure due to either cardiac hypertrophy or cardiac dilation. Alterations in the function of several myocardial organelles such as sarcolemma, sarcoplasmic reticulum, myofibrils, mitochondria, as well as extracellular matrix have been shown to be due to subcellular remodeling as a consequence of changes in gene expression and protein content in failing hearts from cardiomyopathic hamsters. In view of the increased activities of various proteases, including calpains and matrix metalloproteinases in the hearts of genetically determined hamsters, it is proposed that the activation of different proteases may also represent an important determinant of subcellular remodeling and cardiac dysfunction associated with genetic cardiomyopathy.
Adipokines and the cardiovascular system: mechanisms mediating health and disease
Authors: Northcott Josette M. , Yeganeh Azadeh , Taylor Carla G. , Zahradka Peter , Wigle Jeffrey T.
Published: July 2012

This review focuses on the role of adipokines in the maintenance of a healthy cardiovascular system, and the mechanisms by which these factors mediate the development of cardiovascular disease in obesity. Adipocytes are the major cell type comprising the adipose tissue. These cells secrete numerous factors, termed adipokines, into the blood, including adiponectin, leptin, resistin, chemerin, omentin, vaspin, and visfatin. Adipose tissue is a highly vascularised endocrine organ, and different adipose depots have distinct adipokine secretion profiles, which are altered with obesity. The ability of many adipokines to stimulate angiogenesis is crucial for adipose tissue expansion; however, excessive blood vessel growth is deleterious. As well, some adipokines induce inflammation, which promotes cardiovascular disease progression. We discuss how these 7 aforementioned adipokines act upon the various cardiovascular cell types (endothelial progenitor cells, endothelial cells, vascular smooth muscle cells, pericytes, cardiomyocytes, and cardiac fibroblasts), the direct effects of these actions, and their overall impact on the cardiovascular system. These were chosen, as these adipokines are secreted predominantly from adipocytes and have known effects on cardiovascular cells.
Cardioprotective and antihypertensive effects of Enicostemma littorale Blume extract in fructose-fed rats
Authors: Bhatt Niraj M. , Chavda Meenal , Desai Dipali , Zalawadia Rishit , Patel Vaibhav B. , Burade Vinod , Sharma Anita K. , Singal Pawan K. , Gupta Sarita
Published: July 2012

We investigated the protective effects of Enicostemma littorale Blume (EL) extract on hypertension and insulin resistance along with its associated cardiovascular complications in high fructose (HF) fed rats. For this, rats were divided among 4 groups: (i) control, fed laboratory chow; (ii) fed with a high level of fructose; (iii) fed with a high level of fructose plus E. littorale extract; and (iv) fed with a high level of fructose plus rosiglitazone (Rg). EL and Rg treatments were given simultaneously with HF diet. The results show that untreated HF-fed rats showed altered oral glucose tolerance, increased fasting insulin, and increased fasting glucose. These rats also exhibited hypertriglyceridemia, moderate hypertension, platelet hyperaggregability, decreased prothrombin time, activated partial thromboplastin time, altered vascular reactivity, and increased serum levels of enzymes (creatine kinase, type muscle–brain (CK-MB), aspartate aminotransferase (SGOT), lactate dehydrogenase (LDH), and alanine aminotransferase (SGPT). This is the first demonstration of platelet hyperaggregation and prothrombotic alteration in HF-fed rats. HF-fed rats treated with EL showed improved insulin resistance, along with reduced hypertriglyceridemia, hypertension, platelet aggregability, blood coagulation, serum enzymes (CK-MB, SGOT, LDH and SGPT), and vascular reactivity. These effects of EL in HF-induced hypertensive rats might be associated with the suppression of hyperinsulinemia and hypertriglyceridemia, along with its antiatherogenic and antithrombogenic potential. These data indicate that the aqueous extract of EL has great therapeutic potential for the prevention and (or) management of insulin resistance and the associated hypertension.
Genistein prevents isoproterenol-induced cardiac hypertrophy in rats
Authors: Maulik Subir Kumar , Prabhakar Pankaj , Dinda Amit Kumar , Seth Sandeep
Published: July 2012

Genistein, an isoflavone and a rich constituent of soy, possesses important regulatory effects on nitric oxide (NO) synthesis and oxidative stress. Transient and low release of NO by endothelial nitric oxide synthase (eNOS) has been shown to be beneficial, while high and sustained release by inducible nitric oxide synthase (iNOS) may be detrimental in pathological cardiac hypertrophy. The present study was designed to evaluate whether genistein could prevent isoproterenol-induced cardiac hypertrophy in male Wistar rats (150–200 g, 10–12 weeks old) rats. Isoproterenol (5 mg·(kg body weight)–1) was injected subcutaneously once daily for 14 days to induced cardiac hypertrophy. Genistein (0.1 and 0.2 mg·kg–1, subcutaneous injection once daily) was administered along with isoproterenol. Heart tissue was studied for myocyte size and fibrosis. Myocardial thiobarbituric acid reactive substances (TBARS), glutathione (GSH), superoxide dismutase (SOD), catalase levels, and 1-OH proline (collagen content) were also estimated. Genistein significantly prevented any isoproterenol-induced increase in heart weight to body weight ratio, left ventricular mass (echocardiographic), myocardial 1-OH proline, fibrosis, myocyte size and myocardial oxidative stress. These beneficial effects of genistein were blocked by a nonselective NOS inhibitor (L-NAME), but not by a selective iNOS inhibitor (aminoguanidine). Thus, the present study suggests that the salutary effects of genistein on isoproterenol-induced cardiac hypertrophy may be mediated through inhibition of iNOS and potentiation of eNOS activities.
Nutrition and the healthy heart with an exercise boost
Authors: Whayne Thomas F. , Maulik Nilanjana
Published: July 2012

In this era of potent medications and major cardiovascular (CV) procedures, the value of nutrition can be forgotten. A healthy diet is essential, regardless of CV risk. Caloric balance is inherent to a good diet. Despite patients who say they eat little, ideal weight can be maintained if calories are burned. Composition is another component of a healthy diet. The Dietary Approaches to Stop Hypertension (DASH) and Mediterranean diets provide proof of CV benefit from their specific content. Metabolic syndrome (MS) is associated with poor diet and obesity. A healthy diet with good nutrition benefits the MS patient and associated conditions such as obesity and diabetes. Exercise, in conjunction with a healthy diet and good nutrition, helps maintain optimal weight and provides CV benefit such as decreased inflammation and increased vasodilatation. Whether vitamins or other nutritional supplements are important in a healthy diet is unproven. Nevertheless, the most promising data of added benefit to a healthy diet is with vitamin D. Some dietary supplements also have promise. Alcohol, in moderation, especially red wine, has nutritional and heart protective benefits. Antioxidants, endogenous or exogenous, have received increased interest and appear to play a favorable nutritional role. CV health starts with good nutrition.
L-Cysteine supplementation as an adjuvant therapy for type-2 diabetes
Authors: Jain Sushil K.
Published: July 2012

Diabetes remains a major public health issue. According to the American Diabetes Association, 23.5 million, or 10.7% of people in the USA aged 20 years and older, have diabetes. Type-2 diabetes is treated both by controlling the diet and with oral hypoglycemic drugs. However, for many patients, achieving a tight control of glucose is difficult with current regimens. This chapter discusses a relatively low-cost dietary supplement that could be used as an adjuvant therapy for type-2 diabetes. A review of the literature indicates that cysteine-rich whey protein improves glucose metabolism in diabetic animals and type-2 diabetic patients. Similarly, in animal studies, improvement in glucose metabolism is observed after supplementation with L-cysteine, or molecules containing a cysteine moiety. This chapter discusses the biochemical mechanisms by which L-cysteine can upregulate the insulin-dependent signaling cascades of glucose metabolism. Further studies are needed to examine whether clinical interventions using L-cysteine as an adjuvant therapy indeed help to control glycemia and vascular inflammation in the diabetic patient population.
MOLECULAR DYNAMIC SIMULATIONS OF GLASS TRANSITION TEMPERATURE AND MECHANICAL PROPERTIES IN THE AMORPHOUS REGION OF OIL-IMMERSED TRANSFORMER INSULATION PAPER
Authors: WANG YOU-YUAN , YANG TAO , LIAO RUI-JIN
Published: July 2012

The glass transition temperature (Tg) in the amorphous region of an insulation paper is one of the most important characteristics for thermal stability. Molecular dynamic simulations have been performed on three micro-structural models, namely, amorphous pure cellulose, amorphous cellulose with water and amorphous cellulose with oil, to study the microscopic mechanism of the glass transition process for oil-immersed transformer insulation paper. Using the method of specific volume versus temperature curve, the Tg of amorphous pure cellulose, cellulose with water, and cellulose with oil was determined as 448, 418 and 440 K, respectively. The current study may provide some information for thermal aging. The simulation results show that during the glass transition process, both the chain motion and mechanical properties of cellulose changes significantly. Relative to the oil molecules, water molecules immersed in the amorphous region of insulation paper can disrupt hydrogen bonds between cellulose chains. This phenomenon results in a significant reduction in the glass transition temperature and affects the thermal stability of the insulation paper.
WATER EFFECT ON HIGH-PRESSURE ELASTICITY OF OLIVINE, WADSLEYITE AND RINGWOODITE IN Mg2SiO4 BY FIRST-PRINCIPLES
Authors: LIU WEI , TIAN LI-YUN , ZHAO JI-JUN , LIU HONG , LIU LEI , DU JIAN-GUO
Published: July 2012

The hydration effects of water on the high-pressure elastic properties of three Mg 2 SiO 4 polymorphs have been investigated using first-principles simulation density functional theory. The effect of water incorporation was simulated by considering Mg 2 SiO 4 crystals with water contents of 0, 1.65 and 3.3 wt%. With increasing water content, the calculated bulk/shear modulus and sound velocities decrease and their pressure derivatives tend to increase. Thus the hydration effect becomes less obvious at higher pressure. The bulk velocity contrasts from olivine to wadsleyite and from wadsleyite to ringwoodite are found to decrease after water incorporation. Our theoretical results indicate that water content and partition around the phase boundaries have profound impact on the structural and seismic properties of the mantle.
STUDY OF NEAR-NEIGHBOR STRUCTURE OF POINT DEFECTS IN α-FE BY DISPLACEMENT CASCADE
Authors: WANG WEI-LU , LIU WEI , WU XUEBANG , FANG Q. F. , LIU C. S. , HUANG QUN-YING , WU Y. C.
Published: July 2012

Molecular dynamics simulations have been performed to study the primary damage formation in α-Fe by collision cascades in the recoil energy range 0.5–20 keV. Two near-neighbor analysis methods including the near-neighbor defect density (NPDD) analysis and cluster analysis were introduced to characterize the spatial aggregation of point defects and the morphologies of clusters, respectively. It is found that the NPDD of self-interstitial atom (SIA) and the number of Frenkel pairs show a similar variation trend, while the NPDD of vacancy exhibits a peak at shorter time than that of SIA. Furthermore, we find that the clusters of point defects exist mostly in the form of chainlike structure in the course and the end of cascades, but the proportion of chainlike clusters decreases with increasing the number of point defects included in one cluster. Therefore, the present methods are found to be effective to characterize the aggregation and the near-neighbor structure of point defects by displacement cascades at any time.
DISORDERING OF THE CORRELATED STATE OF THE QUANTUM HALL BILAYER AT FILLING FACTOR ν = 1
Authors: PAPIĆ Z. , MILOVANOVIĆ M. V.
Published: July 2012

The phase diagram of a quantum Hall bilayer at total filling ν = 1 contains an incompressible superfluid for small distances d between the layers, as well as the compressible phase corresponding to two uncoupled Fermi liquids for large d. Using exact diagonalization on the sphere and torus geometry, we investigate a long-standing question of the nature of the transition between the two regimes, and the possibility for the existence of a paired phase in the transition region. We find considerable evidence for a direct transition between the superfluid and the Fermi liquid phase, based in particular on the behavior of the ground state energy on the sphere (including appropriate finite-size corrections) as a function of d. At the critical distance dC ≈ 11.6ℓB the topological number ("shift") of the ground state changes, suggesting that tuning the layer separation d in experiment likely leads to a direct transition between the superfluid and the Fermi liquid phase.
DCT-BASED VARIABLE STEP SIZE GRIFFITHS' LMS ALGORITHM FOR RANDOM NOISE CANCELLATION IN ECGs
Authors: HEGDE VEENA N. , DEEKSHIT RAVISHANKAR , SATYANARAYANA P. S.
Published: July 2012

This paper presents a new random noise cancellation technique for cancelling muscle artifact effects from ECG using ALE in the transformed domain. For this a transform domain variable step size griffith least mean square (TVGLMS) algorithm is proposed. The technique is based on the adaptation of the gradient of the error surface. The method frees both the step size and the gradient from observation noise and reduces the gradient mis-adjustment error. The sluggishness introduced due to the averaging of the gradient in the time domain is overcome by the transformed domain approach. The proposed algorithm uses a discrete cosine transform (DCT)-based signal decomposition due to its improved frequency resolution compared to a discrete Fourier transform (DFT). Furthermore, as the data used symmetrical, DCT usage results in low leakage (bias and variance). The performance of the proposed method has been tested on ECG signals combined with WGN, extracted from MIT database, and compared with several existing techniques like LMS, NLMS, and VGLMS.
BIOMECHANICAL INVESTIGATION OF PULSATILE FLOW IN A THREE-DIMENSIONAL ATHEROSCLEROTIC CAROTID BIFURCATION MODEL
Authors: WONG KELVIN K. L. , THAVORNPATTANAPONG P. , CHEUNG SHERMAN C. P. , TU J. Y.
Published: July 2012

It is a well-established fact that atherosclerosis in carotid bifurcation depends on flow parameters such as wall shear stress, flow pulsatility, and blood pressure. However, it is still not clearly verified how atherosclerosis can become aggravated when plaque experiences a high level of shear stress during advance stages of this disease. In this paper, fluid and structural properties in idealistic geometries are analyzed by using fluid-structure interaction (FSI). From our results, the relationship among blood pressure, stenotic compression, and deformation was established. We show that a high level of compression occurs at the stenotic apex, and can potentially be responsible for plaque progression. Moreover, wall shear stress and deformation are significantly affected by the degree of stenosis. Finally, through analysis of the FSI-based simulation results, we can better understand the parameters that influence flow through a stenotic artery and plaque aggravation, and apply the knowledge for the enhancement of clinical research and prediction of treatment outcomes.
PERSONAL AND EXTERNAL FACTORS EFFECT ON WOMEN ENTREPRENEURS: EVIDENCE FROM KUWAIT
Authors: NASER KAMAL , NUSEIBEH RANA , AL-HUSSAINI AHMAD
Published: July 2012

The main objective of the current study is to investigate personal and external factors that might influence women's decisions to become entrepreneurs in Kuwait. To achieve this objective, a questionnaire containing selected variables of women's personal and external factors was distributed to a sample of Kuwaiti women who are mainly studying or have completed their studies at the Public Authority for Applied Education and Training. The participants in the questionnaire survey were asked to express the level of agreement they assign to various variables that might affect their decisions to become entrepreneurs. Although the result of the analysis of the participants' answers revealed that they attach a certain level of agreement to the external factors effect on their decisions to become entrepreneurs, they attached higher level of agreement to personal factors. The Kuwaiti women who participated in the survey believe that getting involved in developing a self-business will enhance their social position and assist them in making independent decisions. Their interests and hobbies together with availability of business ideas would encourage Kuwaiti women to develop their own businesses. Their involvements in developing self-businesses are motivated by profit, given that they can secure the start-up capital. Finally, the participants revealed that religious bindings, together with family responsibilities, influence their decisions to become entrepreneurs.