bluuebunny/crossref_metadata_2025 huggingface dataset:
The Individual and Combined Effects of Glycemic Index and Protein on Glycemic Response, Hunger, and Energy Intake
Authors: Makris Angela P. , Borradaile Kelley E. , Oliver Tracy L. , Cassim Nida G. , Rosenbaum Diane L. , Boden Guenther H. , Homko Carol J. , Foster Gary D.
Published: June 2011

Although high protein and low glycemic index (GI) foods are thought to promote satiety, little is known about the effects of GI, protein, and their interaction on hunger and energy intake several hours following a mixed meal. This study investigated the long term effects of GI, protein, and their combined effects on glucose, insulin, hunger, and energy intake in healthy, sedentary, overweight, and obese adults (BMI of 30.9 ± 3.7 kg/m2). Sixteen individuals participated separately in four testing sessions after an overnight fast. The majority (75%) were non‐Hispanic Blacks. Each consumed one of four breakfast meals (high GI/low protein, high GI/high protein, low GI/low protein, low GI/high protein) in random order. Visual analog scales (VAS) and blood samples were taken at baseline, 15 min, and at 30 min intervals over 4 h following the meal. After 4 h, participants were given the opportunity to consume food ad libitum from a buffet style lunch. Meals containing low GI foods produced a smaller glucose (P < 0.002) and insulin (P = 0.0001) response than meals containing high GI foods. No main effects for protein or interactions between GI and protein were observed in glucose or insulin responses, respectively. The four meals had no differential effect on observed energy intake or self‐reported hunger, satiety, and prospective energy intake. Low GI meals produced the smallest postprandial increases in glucose and insulin. There were no effects for GI, protein, or their interaction on appetite or energy intake 4 h after breakfast.
Weight Loss and Improved Gross Motor Coordination in Children as a Result of Multidisciplinary Residential Obesity Treatment
Authors: D'Hondt Eva , Gentier Ilse , Deforche Benedicte , Tanghe Ann , De Bourdeaudhuij Ilse , Lenoir Matthieu
Published: June 2011

This study evaluated the short‐term effectiveness of a multidisciplinary residential obesity treatment program by describing changes in body weight, related measures, and gross motor co‐ordination. Secondarily, it was examined to what extent the amount of relative weight loss achieved by overweight and obese (OW/OB) participants explained the projected improvement in gross motor co‐ordination. Thirty‐six OW/OB children (aged 10.5 ± 1.4 years, 12 girls and 24 boys) were recruited at the Zeepreventorium VZW (De Haan, Belgium), where they followed a specific program consisting of moderate dietary restriction, psychological support, and physical activity. For reference purposes, an additional group of 36 age‐ and gender‐matched healthy‐weight (HW) children was included in the study. Anthropometric measures were recorded and gross motor co‐ordination was assessed using the Körperkoordinationstest für Kinder (KTK) on two occasions with an interval of 4 months. Regardless of the test moment, OW/OB participants displayed significantly poorer KTK performances (P < 0.001). However, treatment was found to be efficacious in decreasing body weight (Δ 17.9 ± 3.1%, P < 0.001) and generating a significant progress in gross motor co‐ordination performance, with a greater increase in KTK score(s) from baseline to re‐test as compared to HW peers (P < 0.01). Within the OW/OB group, the amount of relative weight loss explained 26.9% of the variance in improvement in overall KTK performance. Therefore, multidisciplinary residential treatment and concomitant weight loss can be considered an important means to upgrade OW/OB children's level of gross motor co‐ordination, which in turn may promote physical activity participation.
Early Myocardial Deformation Changes Associated to Isolated Obesity: A Study Based on 3D‐Wall Motion Tracking Analysis
Authors: Saltijeral Adriana , de Isla Leopoldo Pérez , Pérez‐Rodríguez Olga , Rueda Santiago , Fernandez‐Golfin Covadonga , Almeria Carlos , Rodrigo Jose L. , Gorissen Willem , Rementeria Juan , Marcos‐Alberca Pedro , Macaya Carlos , Zamorano Jose
Published: June 2011

Obesity is considered as a strong risk factor for cardiovascular morbidity and mortality. 3D‐wall motion tracking echocardiography (3D‐WMT) provides information regarding different parameters of left ventricular (LV) myocardial deformation. Our aim was to assess the presence of early myocardial deformation abnormalities in nonselected obese children free from other cardiovascular risk factors. Thirty consecutive nonselected obese children and 42 healthy volunteer children were enrolled. None of them had any cardiovascular risk factor. Every subject underwent a 2D‐echo examination and a 3D‐WMT study. Mean age was 13.9 ± 2.56 and 13.25 ± 2.68 years in the nonobese and obese groups, respectively (59.7% and 40.3% male). Statistically significant differences were found for: interventricular septum thickness, LV posterior wall thickness, LV end‐diastolic volume, LV end‐systolic volume, left atrium volume, LV mass, and lateral annulus peak velocity. Regarding the results obtained by 3D‐WMT assessment, all the evaluated parameters were statistically significantly different between the two groups. When the influence of obesity on the different echocardiographic variables was evaluated by means of multivariate logistic regression analysis, the strongest relationship with obesity was found for LV average circumferential strain (β‐coefficient: 0.74; r2: 0.55; P: 0.003). Thus, obesity cardiomyopathy is associated not only with structural cardiac changes, but also with myocardial deformation changes. Furthermore, this association occurs as early as in the childhood and it is independent from any other cardiovascular risk factor. The most related parameter to obesity is LV circumferential strain.
Hepatic Mitochondrial Energetics During Catch‐Up Fat With High‐Fat Diets Rich in Lard or Safflower Oil
Authors: Crescenzo Raffaella , Bianco Francesca , Falcone Italia , Tsalouhidou Sofia , Yepuri Gayathri , Mougios Vassilis , Dulloo Abdul G. , Liverini Giovanna , Iossa Susanna
Published: June 2011

We have investigated whether altered hepatic mitochondrial energetics could explain the differential effects of high‐fat diets with low or high ω6 polyunsaturated fatty acid content (lard vs. safflower oil) on the efficiency of body fat recovery (catch‐up fat) during refeeding after caloric restriction. After 2 weeks of caloric restriction, rats were isocalorically refed with a low‐fat diet (LF) or high‐fat diets made from either lard or safflower oil for 1 week, and energy balance and body composition changes were assessed. Hepatic mitochondrial energetics were determined from measurements of liver mitochondrial mass, respiratory capacities, and proton leak. Compared to rats refed the LF, the groups refed high‐fat diets showed lower energy expenditure and increased efficiency of fat gain; these differences were less marked with high‐safflower oil than with high‐lard diet. The increase in efficiency of catch‐up fat by the high‐fat diets could not be attributed to differences in liver mitochondrial activity. By contrast, the lower fat gain with high‐safflower oil than with high‐lard diet is accompanied by higher mitochondrial proton leak and increased proportion of arachidonic acid in mitochondrial membranes. In conclusion, the higher efficiency for catch‐up fat on high‐lard diet than on LF cannot be explained by altered hepatic mitochondrial energetics. By contrast, the ability of the high‐safflower oil diet to produce a less pronounced increase in the efficiency of catch‐up fat may partly reside in increased incorporation of arachidonic acid in hepatic mitochondrial membranes, leading to enhanced proton leak and mitochondrial uncoupling.
Differences in the Heritability of Growth and Growth Velocity During Infancy and Associations With FTO Variants
Authors: Choh Audrey C. , Curran Joanne E. , Odegaard Andrew O. , Nahhas Ramzi W. , Czerwinski Stefan A. , Blangero John , Towne Bradford , Demerath Ellen W.
Published: June 2011

While the associations of common variants in the FTO gene with obesity have been widely replicated in adults, there is conflicting evidence regarding their effects in infancy. We hypothesize that the genetic influences on growth traits vary during infancy, and that conflicting results may stem from variation in the ages at which FTO associations have been examined. Using longitudinal weight and length data at 0, 1, 3, 6, 9, 12, 18, 24, 30, and 36 months in 917 (444 females, 473 males) family members from the Fels Longitudinal Study, we used a variance components‐based approach (SOLAR) to: (i) examine differences in heritability (gene‐by‐age interaction) in weight, length, relative weight (BMI and ponderal index (PI)) and instantaneous weight and length velocities over the course of infancy, and (ii) test whether a common FTO variant (rs9939609) was associated with infant growth at three ages (maximum trait heritability, birth and 36 months). All heritabilities at birth (of 39–74%) were significant (P < 3.9 × 10−10), but changed with age (gene‐by‐age interaction, P < 0.05). Weight, relative weight, and weight velocity reached maximum heritabilities (of 76–89%) at 6–9 months, while length and length velocity reached maximum heritabilities (of 96–99%) at 18–30 months. We found no association of rs9939609 with growth status or velocity measured at any age (P > 0.11). This study for the first time demonstrates the fluctuation of genetic influences on infant growth, but further work is required to determine which gene variants explain the strong additive genetic effects observed.
Common Variants in FTO, MC4R, TMEM18, PRL, AIF1, and PCSK1 Show Evidence of Association With Adult Obesity in the Greek Population
Authors: Rouskas Konstantinos , Kouvatsi Anastasia , Paletas Konstantinos , Papazoglou Dimitrios , Tsapas Apostolos , Lobbens Stéphane , Vatin Vincent , Durand Emmanuelle , Labrune Yann , Delplanque Jérôme , Meyre David , Froguel Philippe
Published: June 2011

Twenty‐four single‐nucleotide polymorphisms (SNPs) have been reproducibly associated with obesity. We performed a follow‐up study for obesity in the Greek adult population. A total of 510 obese and 469 lean adults were genotyped for 24 SNPs. We tested the association with obesity status using logistic regression and we evaluated the combined genetic risk of 24 SNPs by calculating the area under the receiver‐operating characteristic (ROC) curves. We nominally replicated the association with obesity (BMI ≥30 kg/m2) of six SNPs in or near the FTO, MC4R, TMEM18, PRL, AIF1, and PCSK1 loci (1.28 ≤ odds ratio (OR) ≤ 1.35; 0.004 ≤ P ≤ 0.043). The discrimination ability for obesity was slightly stronger (P = 9.59 × 10−6) when the genetic information of the 24 SNPs was added to nongenetic risk factors (area under the curve (AUC) = 0.722) in comparison with nongenetic factors analyzed alone (AUC = 0.685). Our data suggest that SNPs in or near the FTO, MC4R, TMEM18, PRL, AIF1, and PCSK1 loci contribute to obesity risk in the Greek population.
Breastfeeding and Subsequent Maternal Visceral Adiposity
Authors: McClure Candace K. , Schwarz Eleanor B. , Conroy Molly B. , Tepper Ping G. , Janssen Imke , Sutton‐Tyrrell Kim C.
Published: June 2011

Women gain visceral fat during pregnancy. Studies examining the impact of breastfeeding on maternal body composition are inconclusive. We examined the extent to which breastfeeding was associated with visceral adiposity in a sample of US women. This was a cross‐sectional analysis of 351 women aged 45–58 years, who were free of clinical cardiovascular disease and had not used oral contraceptives or hormone replacement therapy in the 3 months prior to enrollment in the Study of Women's Health Across the Nation (SWAN)‐Heart Study (2001–2003). History of breastfeeding was self‐reported. Computed tomography was used to assess abdominal adiposity. Among premenopausal/early‐peri‐menopausal mothers, those who never breastfed had 28% greater visceral adiposity (95% confidence interval (CI): 11–49, P = 0.001), 4.7% greater waist‐hip ratio (95% CI: 1.9–7.4, P < 0.001), and 6.49 cm greater waist circumference (95% CI: 3.71–9.26, P < 0.001) than mothers who breastfed all of their children for ≥3 months in models adjusting for study site; age; parity; years since last birth; socioeconomic, lifestyle, and family history variables; early adult BMI; and current BMI. In comparison to women who were nulliparous, mothers who breastfed all of their children for ≥3 months had similar amounts of visceral fat (P > 0.05). In contrast, premenopausal/early‐peri‐menopausal mothers who had never breastfed had significantly greater visceral adiposity (42% (95% CI: 17–70), P < 0.001), waist circumference (6.15 cm (95% CI: 2.75–9.56), P < 0.001), and waist‐hip ratio (3.7% (95% CI: 0.69–6.8), P = 0.02) than nulliparous women. No significant relationships were observed among late peri‐menopausal/postmenopausal women. In conclusion, until menopause, mothers who did not breastfeed all of their children for ≥3 months exhibit significantly greater amounts of metabolically active visceral fat than mothers who had breastfed all of their children for ≥3 months.
Effect of Obesity on Repeat Revascularization in Patients Undergoing Percutaneous Coronary Intervention With Drug‐Eluting Stents
Authors: Wang Zhi Jian , Zhou Yu Jie , Zhao Ying Xin , Liu Yu Yang , Shi Dong Mei , Liu Xiao Li , Yu Miao , Gao Fei
Published: June 2011

Obesity is a major risk factor for developing coronary artery disease. The impact of obesity on prognosis among those with established coronary disease is less clear. The objective of this study was to evaluate the effect of obesity on repeat revascularization in patients undergoing percutaneous coronary intervention (PCI) with drug‐eluting stents (DES). We examined 6,083 patients who were divided into three groups according to BMI: normal (BMI 18.5–24.9 kg/m2, n = 1,592); overweight (BMI 25–29.9 kg/m2, n = 3,026) and obese (BMI >30 kg/m2, n = 1,465). The follow‐up focused on clinical‐driven repeat revascularization, including target lesion revascularization (TLR) and nonTLR. Median follow‐up was 26 months (interquartile range 20–32). There was no significant difference in the incidence of TLR among normal, overweight, and obese patients (6.3% vs. 6.1% vs. 7.1%; P = 0.423). In contrast, the incidence of nonTLR was significantly higher in obese patients compared with normal and overweight (8.4% vs. 6.0% vs. 5.8%, P = 0.003). Multivariate analysis showed that obesity was an independent predictor of nonTLR during follow‐up (hazard ratio = 1.39; 95% confidence interval = 1.06–1.83; P = 0.019), along with diabetes and hypercholesterolemia. Concomitant use of statins was independently associated with decreased risk of nonTLR (hazard ratio = 0.75; 95% confidence interval = 0.62–0.92; P = 0.005). In conclusion, among patients undergoing PCI with DES, obesity was not associated with TLR, but was associated with a higher risk of nonTLR.
Liver Attenuation, Pericardial Adipose Tissue, Obesity, and Insulin Resistance: The Multi‐Ethnic Study of Atherosclerosis (MESA)
Authors: McAuley Paul A. , Hsu Fang‐Chi , Loman Kurt K. , Carr J. Jeffrey , Budoff Matthew J. , Szklo Moyses , Sharrett A. Richey , Ding Jingzhong
Published: June 2011

Insulin resistance is linked to general and abdominal obesity, but its relation to hepatic lipid content and pericardial adipose tissue is less clear. The purpose of this study was to examine cross‐sectional associations of liver attenuation, pericardial adipose tissue, BMI, and waist circumference with insulin resistance. We measured liver attenuation and pericardial adipose tissue using the existing cardiac computed tomography scans in 5,291 individuals free of clinical cardiovascular disease and diabetes in the Multi‐Ethnic Study of Atherosclerosis (MESA) during the study's baseline visit (2000–2002). Low liver attenuation was defined as the lowest quartile and high pericardial adipose tissue as the upper quartile of volume (cm3). We used standard clinical definitions for obesity and abdominal obesity. Insulin resistance was assessed by the homeostasis model assessment of insulin resistance (HOMAIR) index. In multivariate linear regression with all adiposity measures in the model simultaneously, all adiposity measures were significantly (P < 0.0001) associated with insulin resistance: regression coefficients (±s.e.) were 0.31 (±0.02) for low liver attenuation, 0.27 (±0.02) for high pericardial adipose tissue, 0.27 (±0.02) for obesity, and 0.32 (±0.02) for abdominal obesity. We found significant differences (P = 0.003) between standardized liver attenuation and insulin resistance by ethnicity: regression coefficients per 1 s.d. increment were 0.10 ± 0.01 for whites, 0.11 ± 0.02 for Chinese, 0.08 ± 0.2 for blacks, and 0.14 ± 0.01 for Hispanics. Liver attenuation and pericardial adipose tissue were associated with insulin resistance, independent of BMI and waist circumference.
Overweight as a Prognostic Factor in Children With Acute Lymphoblastic Leukemia
Authors: Gelelete Cristina B. , Pereira Sandra H. , Azevedo Alice Maria B. , Thiago Leandro S. , Mundim Mariana , Land Marcelo G.P. , Costa Elaine S.
Published: June 2011

Our purpose was to investigate the prognostic impact of overweight/obesity in 5‐year event‐free survival (EFS) in a cohort of children with acute lymphoblastic leukemia (ALL). We retrospectively analyzed 181 newly diagnosed ALL children enrolled between 1990 and 2009 and treated with Berlin‐Frankfurt‐Munich (BFM) protocols. The majority of children in our cohort were <10 years‐old. Our data clearly indicated that overweight/obesity is an independent predictor of relapse risk, mainly in the intermediate‐ and high‐risk groups (HR) of children. These results could be explained by changes in the chemotherapy pharmacokinetics in overweight/obese patients and by the antiapoptotic effects in leukemic cells caused by adipocytes.
The Effect of Tesofensine on Appetite Sensations
Authors: Gilbert Jo‐Anne , Gasteyger Christoph , Raben Anne , Meier Dieter H. , Astrup Arne , Sjödin Anders
Published: June 2011

Tesofensine (TE), an inhibitor of monoamine presynaptic reuptake, has produced twice the weight loss seen with currently marketed drugs. However, its long term effect on appetite in humans has not been studied. A multicentre phase II trial was divided into two parts (24 weeks each). Part 1 had a randomized, double‐blind, placebo‐controlled design and Part 2, an open‐labeled, single‐group, uncontrolled design. A drug‐free period (12 ± 3 weeks) separated them. In Part 1, participants (n = 158) were assigned to 0.25, 0.5 or 1.0 mg TE, or placebo. Completers of Part 1 were invited to participate in Part 2 (n = 113), during which they all received 0.5 or 1.0 mg TE. Appetite sensations and a composite satiety score (CSS = satiety + fullness + (100 − hunger) + (100 − prospective food consumption) were assessed. In Part 1 TE induced a dose‐dependent increase in CSS at week 12 that correlated with weight loss during the 24 weeks (r = 0.36, P < 0.0001). However, CSS diminished over time as weight loss progressed (e.g., for 1.0 mg; 52 ± 17 mm; 64 ± 13 mm; 55 ± 13 mm at baseline, week 12 and week 24, respectively). After drug withdrawal CSS returned to baseline values (50 ± 17 mm, in the whole sample.), despite the participants' reduced‐weight state (−7.2 ± 6.7 kg, P < 0.0001). The reintroduction of TE in Part 2 increased CSS again (56 ± 17 mm at week 60), regardless of initial treatment/weight loss. We postulate that enhanced satiety is involved in early weight loss. Whether the attenuated effect on appetite seen after 24 weeks is due to a counteracting effect in the weight reduced state or whether the appetite suppressing effect of TE per se diminishes over time is, however, still unclear.
Obesity Reduction Within a Generation: The Dual Roles of Prevention and Treatment
Authors: Lee Joyce M. , Lee Hedwig
Published: June 2011

In 2010, the White House Task Force on Childhood Obesity provided benchmark goals for reducing childhood obesity. We evaluated the balance of prevention and treatment required for achieving Task Force goals in benchmark years 2015, 2020, and 2030. We created a simulation of US birth cohorts (2–19 years) born 2008–2030. For each year, we assumed “old” birth cohorts (part of previous benchmark obesity estimates) would benefit from obesity treatment strategies, and “new” birth cohorts would benefit from obesity prevention strategies. We assessed obesity prevalence that must be achieved through prevention strategies, under varying assumptions of treatment effectiveness. When we assumed a 1% absolute reduction in prevalence through treatment, we found that prevention strategies would need to achieve an obesity prevalence of 12% by 2015, 8% by 2020, and 0.3% by 2030. Because of higher obesity prevalence among minority children, prevention strategies would need to achieve a negative prevalence by 2030, which is implausible. Under more generous assumptions of treatment effectiveness, estimates became positive but remained low. Task Force goals are more difficult to achieve with each benchmark year. Policies must focus on obesity treatment interventions, particularly targeted to racial/ethnic minority children, to make progress in stemming the epidemic.
IUPAC-NIST Solubility Data Series. 90. Hydroxybenzoic Acid Derivatives in Binary and Ternary Systems. Part II. Hydroxybenzoic Acids, Hydroxybenzoates, and Hydroxybenzoic Acid Salts in Nonaqueous Systems
Authors: Goto Ayako , Miyamoto Hiroshi , Salomon Mark , Goto Rensuke , Fukuda Hiroshi , Königsberger Erich , Königsberger Lan-Chi , Scharlin Pirketta
Published: June 2011

The solid-liquid solubility data for well defined nonaqueous binary and ternary systems are reviewed. One component includes hydroxybenzoic acid, hydroxybenzoate, and hydroxybenzoic acid salt, and another component includes a variety of organic compounds (hydrocarbons, alcohols, halogenated hydrocarbons, carboxylic acids, esters, et al.) and carbon dioxide. The ternary systems include mixtures of organic substances of various classes and carbon dioxide. The total number of compilation sheets is 270 for six types of system. Almost all data are expressed as mass percent and mole fraction as well as the originally reported units, while some data are expressed as molar concentration. Critical evaluation was carried out for the binary nonaqueous systems of 2-, 3-, and 4-hydroxybenzoic acids and hydroxybenzoates (methylparaben, ethylparaben, propylparaben, and butylparaben) in alcohols, 1-heptane, and benzene.
Hepatocyte spheroid arrays inside microwells connected with microchannels
Authors: Fukuda Junji , Nakazawa Kohji
Published: June 2011

Spheroid culture is a preferable cell culture approach for some cell types, including hepatocytes, as this type of culture often allows maintenance of organ-specific functions. In this study, we describe a spheroid microarray chip (SM chip) that allows stable immobilization of hepatocyte spheroids in microwells and that can be used to evaluate drug metabolism with high efficiency. The SM chip consists of 300-μm-diameter cylindrical wells with chemically modified bottom faces that form a 100-μm-diameter cell adhesion region surrounded by a nonadhesion region. Primary hepatocytes seeded onto this chip spontaneously formed spheroids of uniform diameter on the cell adhesion region in each microwell and these could be used for cytochrome P-450 fluorescence assays. A row of microwells could also be connected to a microchannel for simultaneous detection of different cytochrome P-450 enzyme activities on a single chip. The miniaturized features of this SM chip reduce the numbers of cells and the amounts of reagents required for assays. The detection of four cytochrome P-450 enzyme activities was demonstrated following induction by 3-methylcholantlene, with a sensitivity significantly higher than that in conventional monolayer culture. This microfabricated chip could therefore serve as a novel culture platform for various cell-based assays, including those used in drug screening, basic biological studies, and tissue engineering applications.
Transport and shear in a microfluidic membrane bilayer device for cell culture
Authors: Inamdar Niraj K. , Griffith Linda G. , Borenstein Jeffrey T.
Published: June 2011

Microfluidic devices have been established as useful platforms for cell culture for a broad range of applications, but challenges associated with controlling gradients of oxygen and other soluble factors and hemodynamic shear forces in small, confined channels have emerged. For instance, simple microfluidic constructs comprising a single cell culture compartment in a dynamic flow condition must handle tradeoffs between sustaining oxygen delivery and limiting hemodynamic shear forces imparted to the cells. These tradeoffs present significant difficulties in the culture of mesenchymal stem cells (MSCs), where shear is known to regulate signaling, proliferation, and expression. Several approaches designed to shield cells in microfluidic devices from excessive shear while maintaining sufficient oxygen concentrations and transport have been reported. Here we present the relationship between oxygen transport and shear in a “membrane bilayer” microfluidic device, in which soluble factors are delivered to a cell population by means of flow through a proximate channel separated from the culture channel by a membrane. We present an analytical model that describes the characteristics of this device and its ability to independently modulate oxygen delivery and hemodynamic shear imparted to the cultured cells. This bilayer configuration provides a more uniform oxygen concentration profile that is possible in a single-channel system, and it enables independent tuning of oxygen transport and shear parameters to meet requirements for MSCs and other cells known to be sensitive to hemodynamic shear stresses.
Perfusion systems that minimize vascular volume fraction in engineered tissues
Authors: Truslow James G. , Tien Joe
Published: June 2011

This study determines the optimal vascular designs for perfusing engineered tissues. Here, “optimal” describes a geometry that minimizes vascular volume fraction (the fractional volume of a tissue that is occupied by vessels) while maintaining oxygen concentration above a set threshold throughout the tissue. Computational modeling showed that optimal geometries depended on parameters that affected vascular fluid transport and oxygen consumption. Approximate analytical expressions predicted optima that agreed well with the results of modeling. Our results suggest one basis for comparing the effectiveness of designs for microvascular tissue engineering.
Responses of endothelial cells to extremely slow flows
Authors: Park Joong Yull , White Joshua B. , Walker Natalie , Kuo Chuan-Hsien , Cha Wansik , Meyerhoff Mark E. , Takayama Shuichi
Published: June 2011

The process of blood vessel formation is accompanied by very minimal flow in the beginning, followed by increased flow rates once the vessel develops sufficiently. Many studies have been performed for endothelial cells at shear stress levels of 0.1–60 dyn/cm2; however, little is known about the effect of extremely slow flows (shear stress levels of 10−4–10−2 dyn/cm2) that endothelial cells may experience during early blood vessel formation where flow-sensing by indirect mass transport sensing rather than through mechanoreceptor sensing mechanisms would become more important. Here, we show that extremely low flows enhance proliferation, adherens junction protein localization, and nitric oxide secretion of endothelial cells, but do not induce actin filament reorganization. The responses of endothelial cells in different flow microenvironments need more attention because increasing evidence shows that endothelial cell behaviors at the extremely slow flow regimes cannot be linearly extrapolated from observations at faster flow rates. The devices and methods described here provide a useful platform for such studies.
Scaffold fabrication in a perfusion culture microchamber array chip by O2 plasma bonding of poly(dimethylsiloxane) protected by a physical mask
Authors: Hattori Koji , Sugiura Shinji , Kanamori Toshiyuki
Published: June 2011

Extracellular matrix (ECM) proteins are required for cell culture. In this paper, we report the use of O2 plasma bonding to fabricate a perfusion culture microchamber array chip with identical-size ECM spots in the isolated microchambers. The chip was fabricated by assembly of two poly(dimethylsiloxane) (PDMS) layers, a microfluidic network layer, and an ECM array layer, which were aligned and then bonded by O2 plasma oxidation with protection of the ECM microarray with a physical mask made from PDMS. We successfully cultivated Chinese hamster ovary K1 cells in the microchambers with fibronectin. In the fibronectin microchambers, the cells adhered and extended after 12 h of static culture and then grew over the course of 1 d of perfusion culture.
Critical Review of Aqueous Solution Reaction Rate Constants for Hydrogen Atoms
Authors: Madden Keith P. , Mezyk Stephen P.
Published: June 2011

Kinetic data published in the peer-reviewed literature over the period of 1988–2007 for H⋅ radical reactions with molecules and ions derived from inorganic and organic solutes in aqueous solution have been critically reviewed. Rate constants for over 250 reactions, as studied by pulse radiolysis, end-product analysis, and other methods, have been tabulated.
Embryonic stem cell bioprinting for uniform and controlled size embryoid body formation
Authors: Xu Feng , Sridharan BanuPriya , Wang ShuQi , Gurkan Umut Atakan , Syverud Brian , Demirci Utkan
Published: June 2011

Embryonic stem cells (ESCs) are pluripotent with multilineage potential to differentiate into virtually all cell types in the organism and thus hold a great promise for cell therapy and regenerative medicine. In vitro differentiation of ESCs starts with a phase known as embryoid body (EB) formation. EB mimics the early stages of embryogenesis and plays an essential role in ESC differentiation in vitro. EB uniformity and size are critical parameters that directly influence the phenotype expression of ESCs. Various methods have been developed to form EBs, which involve natural aggregation of cells. However, challenges persist to form EBs with controlled size, shape, and uniformity in a reproducible manner. The current hanging-drop methods are labor intensive and time consuming. In this study, we report an approach to form controllable, uniform-sized EBs by integrating bioprinting technologies with the existing hanging-drop method. The approach presented here is simple, robust, and rapid. We present significantly enhanced EB size uniformity compared to the conventional manual hanging-drop method.
An Equation of State for the Thermodynamic Properties of Dimethyl Ether
Authors: Wu Jiangtao , Zhou Yong , Lemmon Eric W.
Published: June 2011

A thermodynamic property formulation for dimethyl ether has been developed based on a selection of experimental thermodynamic property data. The formulation includes a fundamental equation, a vapor-pressure equation, and saturated-density equations for liquid and vapor states. In determining the coefficients of the equation of state, multiproperty fitting methods were used that included single-phase pressure-density-temperature (pρT), heat capacity, vapor pressure, and saturated density data. Deviations between experimental and calculated data are generally within the experimental accuracy. The equation of state has been developed to conform to the Maxwell criterion for two-phase liquid-vapor equilibrium states, and is valid for temperatures from the triple-point temperature to 550K, with pressures up to 50MPa and densities up to 19moldm−3. The uncertainties of the equation of state in density are 0.1% for the liquid phase and 0.3% for the vapor phase. In the extended critical region, the uncertainties in density are 0.5%, except for very near the critical point. The uncertainties in vapor pressure are 0.2% above 230K, and increase as temperature decreases. The uncertainties in saturated liquid density are 0.05%, except for near the critical point. The uncertainties in heat capacity are 2.0%. Detailed comparisons between the experimental data and calculated values are given.
Superior oxygen and glucose supply in perfusion cell cultures compared to static cell cultures demonstrated by simulations using the finite element method
Authors: Sugiura Shinji , Sakai Yusuke , Nakazawa Kohji , Kanamori Toshiyuki
Published: June 2011

Oxygen and glucose supply is one of the important factors for the growth and viability of the cells in cultivation of tissues, e.g., spheroid, multilayered cells, and three-dimensional tissue construct. In this study, we used finite element methods to simulate the flow profile as well as oxygen and glucose supply to the multilayered cells in a microwell array chip for static and perfusion cultures. The simulation results indicated that oxygen supply is more crucial than glucose supply in both static and perfusion cultures, and that the oxygen supply through the wall of the perfusion culture chip is important in perfusion cultures. Glucose concentrations decline with time in static cultures, whereas they can be maintained at a constant level over time in perfusion cultures. The simulation of perfusion cultures indicated that the important parameters for glucose supply are the flow rate of the perfusion medium and the length of the cell culture chamber. In a perfusion culture chip made of oxygen-permeable materials, e.g., polydimethylsiloxane, oxygen is hardly supplied via the perfusion medium, but mainly supplied through the walls of the perfusion culture chip. The simulation of perfusion cultures indicated that the important parameters for oxygen supply are the thickness of the flow channel and the oxygen permeability of the walls of the channel, i.e., the type of material and the thickness of the wall.
Preface to Special Topic: Microfluidics in cell biology and tissue engineering
Authors: Dokmeci Mehmet R. , Khademhosseini Ali
Published: June 2011

In this special issue of Biomicrofluidics, a wide variety of applications of microfluidics to tissue engineering and cell biology are presented. The articles illustrate the benefits of using microfluidics for controlling the cellular environment in a precise yet high rate manner using minimum reagents. The topic is very timely and takes a stab at portraying a glimpse of what is to come in this exciting and emerging field of research.
The effect of a scanning flat fold mirror on a cosmic microwave background B-mode experiment
Authors: Grainger William F. , North Chris E. , Ade Peter. A. R.
Published: June 2011

We investigate the possibility of using a flat-fold beam steering mirror for a cosmic microwave background B-mode experiment. An aluminium flat-fold mirror is found to add ∼0.075% polarization, which varies in a scan synchronous way. Time-domain simulations of a realistic scanning pattern are performed, and the effect on the power-spectrum illustrated, and a possible method of correction applied.
Linking large piezoelectric coefficients to highly flexible polarization of lead free BaTiO3-CaTiO3-BaZrO3 ceramics
Authors: Benabdallah F. , Simon A. , Khemakhem H. , Elissalde C. , Maglione M.
Published: June 2011

We report a large d31 piezoelectric coefficient and corresponding electromechanical coupling factor, Kp, of 0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3 (BCTZ50) and 0.68Ba(Zr0.2Ti0.8)O3–0.32(Ba0.7Ca0.3)TiO3 (BCTZ32) lead-free piezoceramics. The piezoelectric coefficient, d31, reaches a high value of 200 pC/N for BCTZ50 at room temperature which is comparable to the one of the soft PZT. This confirms the previously reported d33 for the same material. A useful way to achieve such performances at the expense of a smaller thermal budget is suggested, enabling better control of the ceramics composition and microstructure. Based on pyroelectric and ferroelectric hysteresis loops measurements, we show that such outstanding properties are likely due to the high flexibility of polarization under thermal and electric stresses.
Line-type resonance peaks and their suppression through graphene-based symmetric and asymmetric double barriers
Authors: Sun Lifeng , Guo Yong
Published: June 2011

Resonant tunneling through symmetric and asymmetric double barriers based on monolayer graphene at non-normal incidence is investigated. Due to the evanescent modes inside the barrier, the transmission, as a function of the incident energy, has a gap which can be tuned by the height of the barrier and the incident angle of the electrons. In terms of the coupling between the barriers and the well in the symmetric double barriers, several line-type resonance peaks with a unity value appear in the transmission gap, and the number of the resonance peaks is closely related to the incident angle, the height, and the width of the barrier. The resonant conditions in the transmission gap are derived and discussed. However, the line-type resonance peaks are greatly suppressed through the asymmetric double barriers. The authors demonstrate that line-type peaks possess potential applications in resonant tunneling devices and energy filters.
Nonvolatile bipolar resistive switching in Au/BiFeO3/Pt
Authors: Shuai Yao , Zhou Shengqiang , Bürger Danilo , Helm Manfred , Schmidt Heidemarie
Published: June 2011

Nonvolatile bipolar resistive switching has been observed in an Au/BiFeO3/Pt structure, where a Schottky contact and a quasi-Ohmic contact were formed at the Au/BiFeO3 and BiFeO3/Pt interface, respectively. By changing the polarity of the external voltage, the Au/BiFeO3/Pt is switched between two stable resistance states without an electroforming process. The resistance ratio is larger than two orders of magnitude. The resistive switching is understood by the electric field–induced carrier trapping and detrapping, which changes the depletion layer thickness at the Au/BiFeO3 interface.
Global boundary conditions for a Dirac operator on the solid torus
Authors: Klimek Slawomir , McBride Matt
Published: June 2011

We study a Dirac operator subject to Atiayh-Patodi-Singer-like boundary conditions on the solid torus and shows that the corresponding boundary value problem is elliptic in the sense that the Dirac operator has a compact parametrix.
Quantum mechanics without an equation of motion
Authors: Alhaidari A. D.
Published: June 2011

We propose a formulation of quantum mechanics for a finite level system whose potential function is not realizable and/or analytic solution of the wave equation is not feasible. The system's wavefunction is written as an infinite sum in a complete set of square integrable functions. Interaction in the theory is introduced in function space by a real finite tridiagonal symmetric matrix. The expansion coefficients of the wavefunction satisfy a three-term recursion relation incorporating the parameters of the interaction. Information about the structure and dynamics of the system is contained in the scattering matrix, which is defined in the usual way. The bound state energy spectrum (system's structure) is finite. Apart from the 2M − 1 dimensionless parameters of the interaction matrix, whose rank is M, the theory has one additional scale parameter. In the development, we utilize the kinematic tools of the J-matrix method.
Local structure and magnetic inhomogeneity of nano-sized La0.7Sr0.3MnO3 manganites
Authors: Ulyanov A. N. , Yang D. S. , Mazur A. S. , Krivoruchko V. N. , Levchenko G. G. , Danilenko I. A. , Konstantinova T. E.
Published: June 2011

We present the study of the local structure and magnetic inhomogeneity of nano-sized La0.7Sr0.3MnO3 manganites performed by x-ray absorption fine structure (XAFS) spectroscopy and nuclear magnetic resonance (NMR). Nano-powders with particle size of 50–200 nm (NP1) and 20 nm (NP2), and bulk samples (BS) were studied. EXAFS data show the difference between the local structure of core and outer shell of the nano-particle. The data evidenced that the shell of particles presents the disordered crystalline array. According to the NMR, at low temperature the magnetic state of NP1 sample is homogenous. However, with increase of temperature the two ferromagnetic phases, with strong and weakened double exchange, coexist. The NP2 powder is magnetically homogeneous and characterized by weakened double exchange at all temperatures of the existence of the magneto-ordered state. The results specify on possible existence of characteristic spatial scale below which the phase stratification becomes energetically unfavorable.
Nonlinear pseudo-bosons
Authors: Bagarello F.
Published: June 2011

In a series of recent papers, the author has introduced the notion of (regular) pseudo-bosons showing, in particular, that two number-like operators, whose spectra are \documentclass[12pt]{minimal}\begin{document}${\bb N}_0:={\bb N}\cup \lbrace 0\rbrace$\end{document}N0:=N∪{0}, can be naturally introduced. Here we extend this construction to operators with rather more general spectra. Of course, this generalization can be applied to many more physical systems. We discuss several examples of our framework.
Field modulation of the electronic structure of trilayer graphene
Authors: Wu Bi-Ru
Published: June 2011

Bandgaps play a central role in modern device physics, and a tunable bandgap can provide great flexibility in device design. Herein, an investigation of trilayer graphene modulated using an external electric field is presented. The calculations for trilayer graphene with hexagonal, Bernal, and rhombohedral stacking have been carried out. It was found that the bandgap of rhombohedral trilayer graphene can be tuned using an electric field. Symmetry plays a crucial role in the modulation the bandgap of trilayer graphene through an electric field.
Mixed quantum-classical simulations of charge transport in organic materials: Numerical benchmark of the Su-Schrieffer-Heeger model
Authors: Wang Linjun , Beljonne David , Chen Liping , Shi Qiang
Published: June 2011

The electron-phonon coupling is critical in determining the intrinsic charge carrier and exciton transport properties in organic materials. In this study, we consider a Su-Schrieffer-Heeger (SSH) model for molecular crystals, and perform numerical benchmark studies for different strategies of simulating the mixed quantum-classical dynamics. These methods, which differ in the selection of initial conditions and the representation used to solve the time evolution of the quantum carriers, are shown to yield similar equilibrium diffusion properties. A hybrid approach combining molecular dynamics simulations of nuclear motion and quantum-chemical calculations of the electronic Hamiltonian at each geometric configuration appears as an attractive strategy to model charge dynamics in large size systems “on the fly,” yet it relies on the assumption that the quantum carriers do not impact the nuclear dynamics. We find that such an approximation systematically results in overestimated charge-carrier mobilities, with the associated error being negligible when the room-temperature mobility exceeds ∼4.8 cm2/Vs (∼0.14 cm2/Vs) in one-dimensional (two-dimensional) crystals.
Plant-in-chip: Microfluidic system for studying root growth and pathogenic interactions in Arabidopsis
Authors: Parashar Archana , Pandey Santosh
Published: June 2011

We report a microfluidic platform for the hydroponic growth of Arabidopsis plants with high-resolution visualization of root development and root-pathogen interactions. The platform comprises a set of parallel microchannels with individual input/output ports where 1-day old germinated seedlings are initially placed. Under optimum conditions, a root system grows in each microchannel and its images are recorded over a 198-h period. Different concentrations of plant growth media show different root growth characteristics. Later, the developed roots are inoculated with two plant pathogens (nematodes and zoospores) and their physicochemical interactions with the live root systems are observed.
Spectral analysis of enhanced third harmonic generation from plasmonic excitations
Authors: Li G. X. , Li T. , Liu H. , Li K. F. , Wang S. M. , Zhu S. N. , Cheah K. W.
Published: June 2011

We experimentally achieved enhanced third harmonic generation (THG) from hole-array in gold film. The surface plasmon polarition excitations, considered as the major contribution to this THG enhancement, are elaborately studied by a spectrum-resolved femto-second laser system. The momentum matching conditions between the fundamental and harmonic waves are well established, giving results of a series of clear THG beam spots with respect to different excitation wavelengths. This efficient THG beaming from the pure metallic structure would considerably broaden the research in the field of nonlinear plasmonics.
Surface oxygen vacancy origin of electron accumulation in indium oxide
Authors: Walsh Aron
Published: June 2011

Metal oxides are typically insulating materials that can be made conductive through aliovalent doping and/or non-stoichiometry. Recent studies have identified conductive states at surfaces and interfaces of pure oxide materials; high electron concentrations are present, resulting in a high-mobility two-dimensional electron gas. We demonstrate for In2O3 that the energy required to form an oxygen vacancy decreases rapidly towards the (111) surface, where the coordination environment is lowered. This is a general feature of metal oxide systems that can result in a metal–insulator transition where donors are produced at chemically reduced extended defects.
Rotational and translational self-diffusion in concentrated suspensions of permeable particles
Authors: Abade Gustavo C. , Cichocki Bogdan , Ekiel-Jeżewska Maria L. , Nägele Gerhard , Wajnryb Eligiusz
Published: June 2011

In our recent work on concentrated suspensions of uniformly porous colloidal spheres with excluded volume interactions, a variety of short-time dynamic properties were calculated, except for the rotational self-diffusion coefficient. This missing quantity is included in the present paper. Using a precise hydrodynamic force multipole simulation method, the rotational self-diffusion coefficient is evaluated for concentrated suspensions of permeable particles. Results are presented for particle volume fractions up to 45% and for a wide range of permeability values. From the simulation results and earlier results for the first-order virial coefficient, we find that the rotational self-diffusion coefficient of permeable spheres can be scaled to the corresponding coefficient of impermeable particles of the same size. We also show that a similar scaling applies to the translational self-diffusion coefficient considered earlier. From the scaling relations, accurate analytic approximations for the rotational and translational self-diffusion coefficients in concentrated systems are obtained, useful to the experimental analysis of permeable-particle diffusion. The simulation results for rotational diffusion of permeable particles are used to show that a generalized Stokes-Einstein-Debye relation between rotational self-diffusion coefficient and high-frequency viscosity is not satisfied.