bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of comet formation in single‐cell gel electrophoresis: Loops and fragments
Authors: Afanasieva Katerina , Zazhytska Marianna , Sivolob Andrei
Published: January 2010

We investigated the mechanisms of DNA exit during single‐cell gel electrophoresis (the comet assay) by measuring the kinetics of the comet tail formation. In the neutral comet assay, the rate of DNA exit was found to be dependent on the topological state of DNA, which was influenced by either ethidium bromide or a low radiation dose. The results clearly show that the comet tail is formed by extended DNA loops: the loop extension, being reversible when the DNA torsional constraint remains in the loops, is favored when the constraint is relaxed. The kinetics of the comet formation in the case of a high radiation dose points out that accumulation of the single‐strand breaks causes DNA fragmentation. In contrast to the neutral comet assay, the alkaline comet assay is not related to the chromatin loops. Our results imply that the alkaline treatment induces detachment of the loops from the nuclear matrix, and the comet tail is formed by ssDNA fragments, the ends of which are pulled out from the comet head by electric force. We suggest that the kinetic approach can be considered as an important improvement of the comet assay.
A multichannel gel electrophoresis and continuous fraction collection apparatus for high‐throughput protein separation and characterization
Authors: Choi Megan , Nordmeyer Robert A. , Cornell Earl , Dong Ming , Biggin Mark D. , Jin Jian
Published: January 2010

To facilitate a direct interface between protein separation by PAGE and protein identification by mass spectrometry, we developed a multichannel system that continuously collects fractions as protein bands migrate off the bottom of gel electrophoresis columns. The device was constructed using several short linear gel columns, each of a different percent acrylamide, to achieve a separation power similar to that of a long gradient gel. A “Counter Free‐Flow” elution technique then allows continuous and simultaneous fraction collection from multiple channels at low cost. We demonstrate that rapid, high‐resolution separation of a complex protein mixture can be achieved on this system using SDS‐PAGE. In a 2.5 h electrophoresis run, for example, each sample was separated and eluted into 48–96 fractions over a mass range of ∼10–150 kDa; sample recovery rates were 50% or higher; each channel was loaded with up to 0.3 mg of protein in 0.4 mL; and a purified band was eluted in two to three fractions (200 μL/fraction). Similar results were obtained when running native gel electrophoresis, but protein aggregation limited the loading capacity to about 50 μg per channel and reduced resolution.
Polymer mixtures with enhanced compatibility and extremely low viscosity used as DNA separation media
Authors: Ke Fuyou , Mo Xiulei , Yang Runmiao , Wang Yanmei , Liang Dehai
Published: January 2010

Poor compatibility was the major drawback of polymer mixtures when used as DNA separation media. Using poly(ethylene oxide)‐b‐poly(N,N‐dimethylacrylamide) (PEO44‐b‐PDMA88) and PEO (Mw: 1.3 MDa) as an example, we demonstrated the concept that the compatibility was significantly improved when mixing a homopolymer with its copolymer. Laser light scattering indicated that the major interaction between PEO and PEO‐b‐PDMA in dilute solution was the weak hydrodynamic interaction, which showed almost no effect on the viscosity and the static scattering pattern. In semidilute or concentrated solution, viscosity measurement also suggested good compatibility between the two components. When tested as DNA separation medium by CE, the viscosity of the mixture was extremely low, only 5 cP for 5.0 m/v% PEO‐b‐PDMA+0.1 m/v% PEO at 25°C. The performance on DNA separation could be tuned by varying the concentration of each component as well as the component ratio. Good separation on both dsDNA and ssDNA was achieved.
DNA damage and toxicogenomic analyses of hydrogen sulfide in human intestinal epithelial FHs 74 Int cells
Authors: Attene‐Ramos Matias S. , Nava Gerardo M. , Muellner Mark G. , Wagner Elizabeth D. , Plewa Michael J. , Gaskins H. Rex
Published: January 2010

Hydrogen sulfide (H2S), a metabolic end product of sulfate‐reducing bacteria, represents a genotoxic insult to the colonic epithelium, which may also be linked with chronic disorders such as ulcerative colitis and colorectal cancer. This study defined the early (30 min) and late (4 hr) response of nontransformed human intestinal epithelial cells (FHs 74 Int) to H2S. The genotoxicity of H2S was measured using the single‐cell gel electrophoresis (comet) assay. Changes in gene expression were analyzed after exposure to a genotoxic, but not cytotoxic, concentration of H2S (500 μM H2S) using pathway‐specific quantitative RT‐PCR gene arrays. H2S was genotoxic in a concentration range from 250 to 2,000 μM, which is similar to concentrations found in the large intestine. Significant changes in gene expression were predominantly observed at 4 hr, with the greatest responses by PTGS2 (COX‐2; 7.92‐fold upregulated) and WNT2 (7.08‐fold downregulated). COX‐2 was the only gene upregulated at both 30 min and 4 hr. Overall, the study demonstrates that H2S modulates the expression of genes involved in cell‐cycle progression and triggers both inflammatory and DNA repair responses. This study confirms the genotoxic properties of H2S in nontransformed human intestinal epithelial cells and identifies functional pathways by which this bacterial metabolite may perturb cellular homeostasis and contribute to the onset of chronic intestinal disorders. Environ. Mol. Mutagen. 2010. © 2010 Wiley‐Liss, Inc.
32P‐postlabeling analysis of DNA adducts formed by leukotriene A4 (LTA4)
Authors: Funk Dorothee , Sorg Bernd L. , Lindner Sabine C. , Schmeiser Heinz H.
Published: January 2010

Leukotriene A4 (LTA4), a reactive electrophilic intermediate formed during the biosynthesis of inflammation‐related lipid mediators, has been found to bind covalently to DNA. The major DNA adducts formed by LTA4 in vitro and human cells have been identified by mass spectrometry on the nucleoside level. Here we investigated whether the thin‐layer chromatography (TLC) 32P‐postlabeling method is suitable for the detection of LTA4‐DNA adducts. The reaction of individual deoxynucleoside 3′‐monophosphates with LTA4 in aqueous basic solution yielded numerous adduct spots when analyzed by the two enrichment procedures of the 32P‐postlabeling method—nuclease P1 digestion and butanol extraction. Highest LTA4‐adduct levels were found with deoxyguanosine 3′‐phosphate (around one adduct per 104 normal nucleotides). Under similar reaction conditions LTA4 (25–320 μM) was incubated with calf thymus DNA, then DNA adduct patterns and levels were determined with the TLC 32P‐postlabeling method using both enrichment versions. The same DNA adduct pattern consisting of up to seven spots was observed with both enrichment versions. DNA adduct formation by LTA4 was concentration‐dependent with major adducts being derived from deoxyguanosine. When a human monocytic cell line (Mono Mac 6) was stimulated with arachidonic acid and calcium ionophore LTA4‐DNA adducts were detected by 32P‐postlabeling. However, the level of these endogenously formed DNA adducts was close to the detection limit (3 ± 2 adducts per 108 normal nucleotides). In summary, the TLC 32P‐postlabeling method is suitable for studying DNA adduct formation by LTA4 and can be used for further investigations on the link between inflammation and cancer. Environ. Mol. Mutagen. 2010. © 2010 Wiley‐Liss, Inc.
Molecular biology of aromatic plants and spices. A review.
Authors: Trindade Helena
Published: January 2010

In recent years, molecular tools have been used to help to elucidate some aspects of genetic diversity in aromatic species, the genetic relationships between different cultivars and comparisons of molecular marker analysis to the chemical composition of plants. In this review, an explanation of the most important techniques involving molecular markers is given. A literature survey on molecular markers is presented, with some examples from aromatic plants and spices. However, understanding what controls flavour and aroma production in plants is not an easy task to accomplish. Several aspects of plant secondary metabolism, in particular volatiles production in aromatic plants, are still unknown. The route from genomics to proteomics is not well documented, although some research with model plants has already been performed. To address the question of the synthesis of volatiles, two different approaches are possible and summarized in this review: first, the biochemical and genetic approach; and second, approaches involving functional genomics. Finally, a brief survey of bioinformatics resources is presented. Copyright © 2010 John Wiley & Sons, Ltd.
A meshless numerical method for solving slow mixed convections in containers with discontinuous boundary data
Authors: Tsai Chia‐Cheng , Hsu Tai‐Wen
Published: January 2010

This paper describes the formulations of the method of fundamental solutions (MFS), which is a famous meshless numerical method representing a sought solution by a series of fundamental solutions to solve slow mixed convections in containers with discontinuous boundary data. In the derivations, the fundamental solutions were obtained by using the Hörmander operator decomposition technique. All the velocities, temperatures, pressures, stresses and thermal fluxes corresponding to the fundamental solutions were addressed explicitly in tensor forms. Although the MFS is highly accurate for smooth boundary data, its convergence becomes poor when it is applied to problems with discontinuous boundary data. To compensate for this drawback, we enriched the MFS by adding the local discontinuous solutions to the series of fundamental solutions. This enriched MFS was applied to solve the benchmark problems of a lid‐driven cavity and natural convection in rectangular containers. In addition, the numerical solutions were compared with the analytical solutions. Then, the meshless numerical method was further utilized to solve mixed convections in a triangular cavity and a cavity with a cosine‐shaped bottom. These numerical results demonstrated the applicability of the enriched MFS to two‐dimensional mixed convections in containers with discontinuous boundary data. Copyright © 2010 John Wiley & Sons, Ltd.
Performance on Stroop‐like assessments of inhibitory control by 4‐ and 5‐year‐old children
Authors: Pasalich Dave S. , Livesey David J. , Livesey Evan J.
Published: January 2010

The rapid development of an aspect of executive functioning (EF), inhibitory control (IC), between the ages of 3‐ and 5‐years, leads to an increase in a child's capacity to suppress inappropriate responding and therefore activate the necessary resources to carry‐out goal‐directed activity (Psychological Bulletin, 1997, 121, 65–94). To measure EF in children, tasks administered clinically to adults are adapted. The Day–Night Stroop (DNS) is a pictorial modification of the Stroop Test (Journal of Experimental Psychology, 1935, 18, 642–662), developed for pre‐literate children. Although suitable as a measure of IC in 3‐ to 4‐year‐old children, ceiling effects have been reported on the DNS in slightly older preschoolers. The present study attempted to overcome this limitation by examining the suitability of two modified versions of the DNS in 4‐ to 5‐year‐old preschoolers. To investigate the executive demands made by both Stroop‐like tasks, their associations with another measure of IC (stop‐signal task) and a measure of working memory were examined. Counter to expectations, no significant association was found in performance between the two Stroop‐like tasks; however, the modified DNS developed in this study showed significant relationships with the other executive tasks. The results are discussed in relation to the different methodologies used by these Stroop measures. Implications of this study suggest that researchers should consider more test‐specific factors when assessing EF in young children. Copyright © 2010 John Wiley & Sons, Ltd.
Dietary zinc absorption: A play of Zips and ZnTs in the gut
Authors: Wang Xiaoxi , Zhou Bing
Published: January 2010

Studies on dietary zinc absorption are of fundamental nutritional significance, owing to the ubiquity of zinc in biological processes and the severe outcomes of zinc deficiency in humans. Insights into the molecular basis of dietary zinc absorption have advanced in recent years through functional characterization of zinc transporters in cell culture, immunohistochemical studies on rodent intestine and analysis of gene knockout mice. Zinc transporters with manifested expression in enterocytes include ZnT1, ZnT2, ZnT4, ZnT5, ZnT6, ZnT7, Zip4, and Zip5. Among them, ZIP4, the gene responsible for Acrodermatitis enteropathica, an inherited human zinc deficiency, mediates dietary zinc uptake into enterocytes across the apical membrane, while ZnT1 is involved in zinc efflux from enterocytes across the basolateral membrane into circulation. The intracellular trafficking pathways for zinc retention and movement between apical and basolateral sides of the enterocytes have yet to be defined. The utilization of Drosophila model in elucidating molecular mechanisms of dietary zinc absorption is also discussed in this review. © 2010 IUBMB IUBMB Life, 62(3): 176–182, 2010
Job and wage mobility with minimum wages and imperfect compliance
Authors: Eckstein Zvi , Ge Suqin , Petrongolo Barbara
Published: January 2010

We propose a job search model with minimum wage regulations and imperfect compliance to explain the doubling of the mean and variance of hourly earnings of white males during the first 18 years of labor market experience. The model encompasses job mobility and on‐the‐job wage growth as sources of wage dynamics, and is estimated by simulated generalized method of moments using data from the National Longitudinal Survey of Youths 1979. Our estimates provide a good fit for the observed levels and trends of the main job and wage mobility data, and for the increase in the mean and variance of wages over the life cycle, as well as for the fall in the fraction of workers paid below the minimum wage. Job mobility explains 40–50% of the observed wage growth. Increases in the minimum wage and/or compliance deliver small effects on the wage distribution and the nonemployment rate. Copyright © 2010 John Wiley & Sons, Ltd.
Corrosion study of iron‐cobalt alloys for MRI‐based propulsion embedded in untethered microdevices operating in the vascular network
Authors: Pouponneau Pierre , Savadogo Oumarou , Napporn Teko , Yahia L'hocine , Martel Sylvain
Published: January 2010

Our group have shown in an experiment performed in the carotid artery of a living swine that magnetic gradients generated by a clinical magnetic resonance imaging (MRI) system could propel and navigate untethered medical microdevices and micro‐nanorobots in the human vasculature. The main problem with these devices is that the metal necessary for magnetic propulsion may corrode and induce cytotoxic effects. The challenge, then, is to find an alloy with low corrosion yet providing an adequate magnetization level for propulsion in often stringent physiological conditions. Because of their high magnetization, we studied the corrosion behavior of two iron‐cobalt alloys, Permendur (49% Fe, 49% Co, 2% V) and Vacoflux 17 (81% Fe, 17% Co, 2% Cr), in physiological solution by potentiodynamic polarization assay, surface analysis, and corrosion electrolyte analysis. Both alloys exhibited low corrosion parameters such as a corrosion potential (Ecorr) of −0.57 V/SCE andEcorrof −0.42 V/SCE for Vacoflux 17. The surface of Permendur samples was homogenously degraded. Vacoflux 17 surface was impaired by cracks and crevices. Both alloys had a stoichiometric dissolution in the electrolyte, and they released enough cobalt to induce cytotoxic effects. This study concluded that Fe‐Co alloys could be used preferably in medical microdevices if they were coated so as not to come in contact with physiological solutions. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010
Characterization of parylene C as an encapsulation material for implanted neural prostheses
Authors: Hassler Christina , von Metzen Rene P. , Ruther Patrick , Stieglitz Thomas
Published: January 2010

The applicability of parylene C as an encapsulation material for implanted neural prostheses was characterized and optimized. The adhesion of parylene C was tested on different substrate materials, which were commonly used in neural prostheses and the efficiency of different adhesion promotion methods was investigated. On Si3N4, platinum, and on a first film of parylene C, a satisfactory adhesion was achieved with Silane A‐174, which even withstood standard steam sterilization. The adhesion to gold and polyimide could not be improved sufficiently with the tested methods. Furthermore, tensile tests and measurements of the degree of crystallinity were performed on untreated, on steam sterilized, and on annealed parylene C layers to investigate the influence of thermal treatment. This led to more brittle and stiffer films due to an increase in the crystalline portion in the parylene layers. Finally, an electrochemical impedance spectroscopy was used to test if a parylene C layer was able to protect a metallic structure against corrosion on a Si3N4substrate. The results indicated that this could be only possible by treating the substrate with Silane A‐174. To receive parylene C layers with a good encapsulation performance, it is important to consider the materials, which are used in the neural prosthesis, to find the best suited process parameters. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010
In‐vivostudies on intraperitoneally administrated poly(vinyl alcohol)
Authors: Jiang Yanjiao , Schädlich Andreas , Amado Elkin , Weis Christine , Odermatt Erich , Mäder Karsten , Kressler Jörg
Published: January 2010

The fate of poly(vinyl alcohol) (PVA, 195,000 g/mol) was studied in rabbits and nude mice after intraperitoneal (i.p.) administration.In‐vivofluorescence imaging using nude mice allowed for studies of tetramethylrhodamine labeled PVA distribution in the body and tracking the urinary excretion. The excreted PVA was studied in detail after collecting the urine of rabbits over a time period of 28 days. The PVA was separated from the urine by dialysis and analyzed by FTIR spectroscopy,1H‐NMR spectroscopy, and size exclusion chromatography (SEC). Even after extensive dialysis, it was found that the excreted PVA showed a characteristic brownish color. The spectroscopic techniques revealed that this color was caused by the urine pigment (a metabolite of bilirubin) that could not be separated completely from the PVA. SEC showed unambiguously that the PVA with the very high molar mass had a glomerular permeability in the kidneys. Simultaneously, histological studies of the kidneys and the liver demonstrated that the tissues did not show any obvious damage. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010
Enhanced differentiation of human embryonic stem cells to mesenchymal progenitors by inhibition of TGF-β/activin/nodal signaling using SB-431542
Authors: Mahmood Amer , Harkness Linda , Schrøder Henrik Daa , Abdallah Basem M , Kassem Moustapha
Published: January 2010

Directing differentiation of human embryonic stem cells (hESCs) into specific cell types using an easy and reproducible protocol is a prerequisite for the clinical use of hESCs in regenerative-medicine procedures. Here, we report a protocol for directing the differentiation of hESCs into mesenchymal progenitor cells. We demonstrate that inhibition of transforming growth factor β (TGF-β)/activin/nodal signaling during embryoid body (EB) formation using SB-431542 (SB) in serum-free medium markedly upregulated paraxial mesodermal markers (TBX6, TBX5) and several myogenic developmental markers, including early myogenic transcriptional factors (Myf5, Pax7), as well as myocyte-committed markers [NCAM, CD34, desmin, MHC (fast), α-smooth muscle actin, Nkx2.5, cTNT]. Continuous inhibition of TGF-β signaling in EB outgrowth cultures (SB-OG) enriched for myocyte progenitor cells; markers were PAX7+ (25%), MYOD1+ (52%), and NCAM+ (CD56) (73%). DNA microarray analysis revealed differential upregulation of 117 genes (>2-fold compared with control cells) annotated to myogenic development and function. Moreover, these cells showed the ability to contract (80% of the population) and formed myofibers when implanted intramuscularly in vivo. Interestingly, SB-OG cells cultured in 10% fetal bovine serum (FBS) developed into a homogeneous population of mesenchymal progenitors that expressed CD markers characteristic of mesenchymal stem cells (MSCs): CD44+ (100%), CD73+ (98%), CD146+ (96%), and CD166+ (88%) with the ability to differentiate into osteoblasts, adipocytes, and chondrocytes in vitro and in vivo. Furthermore, microarray analysis of these cells revealed downregulation of genes related to myogenesis: MYH3 (−167.9-fold), ACTA1 (−161-fold), MYBPH (−139-fold), ACTC (−100.3-fold), MYH8 (−45.5-fold), and MYOT (−41.8-fold) and marked upregulation of genes related to mesoderm-derived cell lineages. In conclusion, our data provides a simple and versatile protocol for directing the differentiation of hESCs into a myogenic lineage and then further into mesenchymal progenitors by blocking the TGF-β signaling pathway. © 2010 American Society for Bone and Mineral Research
Velocities of bone mineral accrual in black and white American children
Authors: Hui Siu L , Perkins Anthony J , Harezlak Jaroslaw , Peacock Munro , McClintock Cindy L , Johnston C Conrad
Published: January 2010

Black adults have higher bone mass than whites in the United States, but it is not clear when black children gain bone mineral faster than white children. We performed a cohort study to compare the growth velocity of total-body bone mineral content (TBMC) between black and white children of the same sex at different ages and stages of sexual maturity. TBMC and total-body area were measured in a cohort of 188 black and white boys and girls aged 5 to 15 years annually for up to 4 years. Rates of change in TBMC and area were found to vary with age and with Tanner stage. For both TBMC and area, growth velocities between black and white children differed significantly across Tanner stages. Age-specific velocities were higher in black children during prepuberty and initial entry into puberty but reversed in subsequent Tanner stages. Despite earlier entry into each Tanner stage, black children spent only an average of only 0.2 year longer in Tanner stages II through IV, and total gain in TBMC from age 5 to 15 was not higher in whites. In conclusion, the higher bone mass in black adults compared with whites cannot be attributed to faster accrual during puberty. It is due to black children's higher rate of bone mineral accrual in prepuberty and plausibly in postpuberty. Most of the racial difference in TBMC velocity can be explained by growth in size. © 2010 American Society for Bone and Mineral Research
A key role for membrane transporter NKCC1 in mediating chondrocyte volume increase in the mammalian growth plate
Authors: Bush Peter G , Pritchard Meredith , Loqman Mohamad Y , Damron Timothy A , Hall Andrew C
Published: January 2010

The mechanisms that underlie growth plate chondrocyte volume increase and hence bone lengthening are poorly understood. Many cell types activate the Na-K-Cl cotransporter (NKCC) to bring about volume increase. We hypothesised that NKCC may be responsible for the volume expansion of hypertrophic chondrocytes. Metatarsals/metacarpals from 16 rat pups (P7) were incubated in the presence/absence of the specific NKCC inhibitor bumetanide and measurement of whole-bone lengths and histologic analysis of the growth plate were done after 24 hours. Fluorescent NKCC immunohistochemistry was visualised using a confocal laser scanning microscopy on seven rat tibial growth plates (P7). Microarray analysis was performed on mRNA isolated from proliferative and hypertrophic zone cells of tibial growth plates from five rats of each of three ages (P49/53/58). Exposure to bumetanide resulted in approximately 35% reduction (paired Student's t test, p < .05) of bone growth in a dose-dependent manner; histologic analysis showed that a reduction in hypertrophic zone height was responsible. Quantification of fluorescence immunohistochemistry revealed a significant (paired Student's t test, p < .05) change in NKCC from the intracellular space of proliferative cells to the cytosolic membrane of hypertrophic zone cells. Further, microarray analysis illustrated an increase in NKCC1 mRNA between proliferative and hypertrophic cells. The increase in NKCC1 mRNA in hypertrophic zone cells, its cellular localization, and reduced bone growth in the presence of the NKCC inhibitor bumetanide implicate NKCC in growth plate hypertrophic chondrocyte volume increase. Further investigation is warranted to determine the regulatory control of NKCC in the mammalian growth plate and the possible detrimental effect on bone growth with chronic exposure to loop diuretics. © 2010 American Society for Bone and Mineral Research
TNF-α's effects on proliferation and apoptosis in human mesenchymal stem cells depend on RUNX2 expression
Authors: Ghali Olfa , Chauveau Christophe , Hardouin Pierre , Broux Odile , Devedjian Jean-Christophe
Published: January 2010

RUNX2 is a bone-specific transcription factor that plays a critical role in prenatal bone formation and postnatal bone development. It regulates the expression of genes that are important in committing cells into the osteoblast lineage. There is increasing evidence that RUNX2 is involved in osteoblast proliferation. RUNX2 expression increases during osteoblast differentiation, and recent data even suggest that it acts as a proapoptotic factor. The cytokine tumor necrosis factor α (TNF-α) is known to modulate osteoblast functions in a manner that depends on the differentiation stage. TNF-α affects the rate at which mesenchymal precursor cells differentiate into osteoblasts and induces apoptosis in mature osteoblasts. Thus we sought to establish whether or not the effects of TNF-α and fetal calf serum on proliferation and apoptosis in human mesenchymal stem cells (hMSCs) were dependent on RUNX2 level and activity. We transfected hMSCs with small interfering RNAs (siRNAs) directed against RUNX2 and found that they proliferated more quickly than control hMSCs transfected with a nonspecific siRNA. This increase in proliferation was accompanied by a rise in cyclin A1, B1, and E1 expression and a decrease in levels of the cyclin inhibitor p21. Moreover, we observed that RUNX2 silencing protected hMSCs from TNF-α's antiproliferative and apoptotic effects. This protection was accompanied by the inhibition of caspase-3 activity and Bax expression. Our results confirmed that RUNX2 is a critical link between cell fate, proliferation, and growth control. This study also suggested that, depending on the osteoblasts' differentiation stage, RUNX2 may control cell growth by regulating the expression of elements involved in hormone and cytokine sensitivity. © 2010 American Society for Bone and Mineral Research
Preoperative carcinoembryonic antigen level as an independent prognostic factor in potentially curative colon cancer
Authors: Huh Jung Wook , Oh Byung Ryul , Kim Hyeong Rok , Kim Young Jin
Published: January 2010

Objective

We evaluated the prognostic value of the preoperative serum carcinoembryonic antigen (CEA) level in patients with colon cancer.

Methods

We reviewed 474 patients who underwent potentially curative resection for nonmetastatic colon cancer. Patients were categorized into two groups according to the preoperative serum CEA level: low CEA (<5 ng/ml) and high CEA (≥5 ng/ml) groups.

Results

During the median 45‐month follow‐up period, the 5‐year overall and disease‐free survival rates for patients with a low CEA level were 81.7% and 82.4%, respectively, which were significantly higher than the rates for those with a high CEA level (69.9%; P = 0.011 and 70.6%; P = 0.002, respectively). A multivariate analysis revealed that a preoperative serum CEA level was a significant independent prognostic factor for both overall survival (P = 0.021) and disease‐free survival (P = 0.026). Both the overall and disease‐free survival rates in patients with stage II tumors differed significantly between the low and high CEA groups, whereas the rates did not different between those with stage I and III tumors.

Conclusions

Preoperative serum CEA is a reliable predictor of recurrence and survival after curative surgery in patients with colon cancer, particularly in those classified as having stage II disease. J. Surg. Oncol. 2010; 101:396–400. © 2010 Wiley‐Liss, Inc.
Primary and secondary angiosarcoma of the breast: The Mayo Clinic experience
Authors: Scow Jeffrey S. , Reynolds Carol A. , Degnim Amy C. , Petersen Ivy A. , Jakub James W. , Boughey Judy C.
Published: January 2010

Background and Objectives

Angiosarcoma of the breast can be divided into primary and secondary. The objective was to determine clinicopathologic factors associated with breast angiosarcoma and to compare primary versus secondary angiosarcoma.

Methods

Breast angiosarcoma cases at Mayo Clinic from 1960 to 2008 were identified. Clinicopathologic factors were reviewed. Characteristics of primary and secondary angiosarcoma were compared.

Results

Twenty‐seven cases of primary angiosarcoma and 14 cases of secondary angiosarcoma were identified. The median age of primary angiosarcoma patients was lower than that of secondary angiosarcoma—43 years versus 73 years (P < 0.0001). Primary angiosarcoma more frequently presented with a mass, whereas secondary angiosarcoma presented with a rash (P < 0.0001). Median time from radiation to secondary angiosarcoma diagnosis was 6.8 years. Median tumor size was 7.0 cm for primary angiosarcoma and 5.0 cm for secondary angiosarcoma (P = 0.7). Tumors were high grade in 33% of primary angiosarcoma and 82% of secondary angiosarcoma (P = 0.02). Five‐year survival for primary and secondary angiosarcoma was 46% and 69%, respectively (P = 0.8).

Conclusion

Primary angiosarcoma occurs in younger patients than secondary and more frequently presents with a mass. Mastectomy is the mainstay of treatment for breast angiosarcoma. Breast angiosarcoma is a rare malignancy with poor long‐term prognosis. J. Surg. Oncol. 2010; 101:401–407. © 2010 Wiley‐Liss, Inc.
Reduction of periprosthetic infection with silver‐coated megaprostheses in patients with bone sarcoma
Authors: Hardes Jendrik , von Eiff Christof , Streitbuerger Arne , Balke Maurice , Budny Tymoteus , Henrichs Marcel P. , Hauschild Gregor , Ahrens Helmut
Published: January 2010

Background and Objectives

The placement of megaprostheses in patients with bone sarcoma is associated with high rates of infection, despite prophylactic antibiotic administration. In individual cases, secondary amputation is unavoidable in the effort to cure infection.

Methods

The infection rate in 51 patients with sarcoma (proximal femur, n = 22; proximal tibia, n = 29) who underwent placement of a silver‐coated megaprosthesis was assessed prospectively over a 5‐year period, along with the treatment administered for infection. The infection rate was compared with the data for 74 patients in whom an uncoated titanium megaprosthesis (proximal femur, n = 33; proximal tibia, n = 41) was implanted.

Results

The infection rate was substantially reduced from 17.6% in the titanium to 5.9% in the silver group. Whereas 38.5% of patients in the titanium group ultimately had to undergo amputation when periprosthetic infection developed, these mutilating surgical procedures were not necessary in the study group.

Conclusions

The use of silver‐coated prostheses reduced the infection rate in the medium term. In addition, less aggressive treatment of infection was possible in the group with silver‐coated prostheses. Further studies with longer term follow‐up periods and larger numbers of patients are warranted in order to confirm these encouraging results. J. Surg. Oncol. 2010; 101:389–395. © 2010 Wiley‐Liss, Inc.
Cruise visitors' experience in a Mediterranean port of call
Authors: Andriotis Konstantinos , Agiomirgianakis George
Published: January 2010

This study aims to provide a better understanding on cruise travel experience by studying cruise ship passengers motivation, satisfaction and likelihood of return to the port of Heraklion (Crete, Greece). From the findings, it is evident that ‘exploration’ and ‘escape’ were among the main motivations of visitors, and ‘product and services’ as well as ‘tour pace’ were significant dimensions in shaping overall satisfaction levels. Nevertheless, onshore activities were restricted to sightseeing and shopping, because of the limited available time. Based on these findings, relevant proposals are made in order to provide positive port experiences. Copyright © 2010 John Wiley & Sons, Ltd.
Negativity indices for definite and indefinite Sturm‐Liouville problems
Authors: Binding Paul , Möller Manfred
Published: January 2010

Various notions of indices for definite and indefinite Sturm‐Liouville problems are introduced and relations between them are investigated (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Krein–von Neumann extension and its connection to an abstract buckling problem
Authors: Ashbaugh Mark S. , Gesztesy Fritz , Mitrea Marius , Shterenberg Roman , Teschl Gerald
Published: January 2010

We prove the unitary equivalence of the inverse of the Krein–von Neumann extension (on the orthogonal complement of its kernel) of a densely defined, closed, strictly positive operator, S ≥ εIH for some ε > 0 in a Hilbert space H to an abstract buckling problem operator.

In the concrete case where in L2(Ω; dnx) for Ω ⊂ ℝn an open, bounded (and sufficiently regular) domain, this recovers, as a particular case of a general result due to G. Grubb, that the eigenvalue problem for the Krein Laplacian SK (i.e., the Krein–von Neumann extension of S),
SKv = λv, λ ≠ 0,
is in one‐to‐one correspondence with the problem of the buckling of a clamped plate,
(‐Δ)2u = λ (‐Δ)u in Ω, λ ≠ 0, u ∈ H02(Ω),
where u and v are related via the pair of formulas
u = SF‐1 (‐Δ)v, v = λ‐1(‐Δ)u,
with SF the Friedrichs extension of S.

This establishes the Krein extension as a natural object in elasticity theory (in analogy to the Friedrichs extension, which found natural applications in quantum mechanics, elasticity, etc.) (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Artifact usefulness and usage in sensemaking handoffs
Authors: Sharma Nikhil , Furnas George
Published: January 2010

The complexities of sensemaking suggest that collaboration should be difficult, requiring a rich ecology of collaboration support. This can be a problem for handoff sensemaking, where one person must continue where another has left off, sometimes with only material artifacts as the basis of the handoff. A detailed analysis of essential attributes of sensemaking tasks, and elements identified in the computer supported collaborative work literature were combined to yield insight into handoff sensemaking and guide empirical work. A lab‐study showed that handoffs relying only on artifacts from previous sensemaking could be successful. The lab studies also indicated timing and quality affects on the sensemaking handoffs, with different quality materials used differently, and early efforts possibly being particularly difficult to hand off. Design of support for sensemaking handoffs will have to take such effects into account.
“It challenges members to think of their work through another kind of specialist's eyes”: Exploration of the benefits and challenges of diversity in digital project teams
Authors: Siemens Lynne , Duff Wendy , Cunningham Richard , Warwick Claire
Published: January 2010

Digital project teams are by definition comprised of people with various skills, disciplines and content knowledge. Collaboration within these teams is undertaken by librarians, academics, undergraduate and graduate students, research assistants, computer programmers and developers, content experts, and other individuals. While this diversity of people, skills and perspectives creates benefits for the teams, at the same time, it creates a series of challenges which must be minimized to ensure project success. Drawing upon interview and survey data, this paper explores the benefits, advantages, and challenges associated with these types of project teams. It will conclude with a series of recommendations focused on harnessing the advantages while minimizing the challenges.
Information Science in the web era: A term‐based approach to domain mapping
Authors: Ibekwe‐SanJuan Fidelia
Published: January 2010

We propose a methodology for mapping the research in Information Science (IS) field based on a combined use of symbolic (linguistic) and numeric information. Using the same list of 12 IS journals as in earlier studies on this same topic (White & McCain1998; Zhao & Strotmann2008a&b), we mapped the structure of research in IS for two consecutive periods: 1996‐2005 and 2006‐2008. We focused on mapping the content of scientific publications from the title and abstract fields of underlying publications. The labels of clusters were automatically derived from titles and abstracts of scientific publications based on linguistic criteria. The results showed that while Information Retrieval (IR) and Citation studies continued to be the two structuring poles of research in IS, other prominent poles have emerged: webometrics in the first period (1996‐2005) evolved into general web studies in the second period, integrating more aspects of IR research. Hence web studies and IR are more interwoven. There is still persistence of user studies in IS but now dispersed among the web studies and the IR poles. The presence of some recent trends in IR research such as automatic summarization and the use of language models were also highlighted by our method. Theoretic research on “information science” continue to occupy a smaller but persistence place. Citation studies on the other hand remains a monolithic block, isolated from the two other poles (IR and web studies) save for a tenuous link through user studies. Citation studies have also recently evolved internally to accommodate newcomers like “h‐index, Google scholar and the open access model”. All these results were automatically generated by our method without resorting to manual labeling of specialties nor reading the publication titles. Our results show that mapping domain knowledge structures at the term level offers a more detailed and intuitive picture of the field as well as capturing emerging trends.
Perceived competence and reading enjoyment as contributors to information skills and digital technology knowledge
Authors: Reynolds Rebecca , Arnone Marilyn , Marshall Todd
Published: January 2010

This article reports on the contributions of perceived competence in information and digital skills, perceived competence in reading, and the disposition to read for enjoyment to actual performance in an information and digital literacy knowledge and skills test among 1272 eighth grade students in 20 states who participated in the study. The data support the importance of affective correlates to information sikills and digital technology knowledge, including the disposition to read for enjoyment, which is emphasized in the new American Association for School Librarian's (AASL) Standards for the 21st Century Learner. The study is grounded in Self‐Determination Theory (SDT) and is part of a larger investigation on digital and information literacy and 21st Century dispositions for learning. Implications for curriculum design are discussed.
Personal and external determinants of medical bloggers' knowledge sharing behavior
Authors: Karimi Faezeh , Chiang Choon Poo Danny
Published: January 2010

This paper investigates the factors affecting medical bloggers' knowledge sharing behavior from both personal and external aspects. We develop a model based on the social cognitive theory and augment it with the social capital theory. The model is empirically examined based on the survey data collected from 75 bloggers writing on medical issues, and evaluated with confirmatory factor analysis and structural equation modeling. Among the personal factors, we examined outcome expectations including reputation and enjoyment in helping others. Encouragement by others, identification and interaction ties were investigated as external factors. Enjoyment in helping others and reputation were found to have significant direct affect on medical bloggers' knowledge sharing behavior, while encouragement by others, identification, and interaction ties showed no significant direct affect. However, encouragement by others exhibited significant impact on reputation and enjoyment in helping others. The implications for theory and practice, and future possible research are discussed.
Analyzing cross‐reference transactions between authors by use of an asymmetric proximity measure and multidimensional unfolding
Authors: Schneider Jesper W. , Borlund Pia
Published: January 2010

The present paper explores simultaneous modelling of cross‐reference activity between authors by use of asymmetric proximities and multidimensional unfolding. We thereby model and map both citing and cited relations between authors in a common space. This enables a more comprehensive comparison of the author's dual roles of citing and being cited in a reference network. We model a set of 31 authors and compare the results to a recent author co‐citation study of Information Science. We find that multidimensional unfolding is a reliable and insightful technique for modelling authors' citing and cited dimensions simultaneously. The common space of citing and cited positions exemplify that some authors have substantial discrepancies between their citing behaviour and the way their works are used by peers in the set. Further, modelling mutual relationships as asymmetric brings more accuracy and nuances into the maps as relationships become overt. Finally, the study discusses how high publication activity influences mapping results considerably. To counter this effect, we demonstrate the appropriateness of correcting data for main effects by use of an asymmetric proximity measure of odds ratios.
Evaluating the metadata quality of the IPL
Authors: Ma Shanshan , Lu Caimei , Lin Xia , Galloway Mike
Published: January 2010

Metadata quality is directly related to the quality of services provided by digital libraries. The paper presents results from evaluating the metadata quality of the IPL (www.ipl.org). Two evaluation methods were used: a preliminary automatic evaluation and a human involved evaluation using a survey. The automatic evaluation was focused on the completeness of major IPL metadata fields. The human evaluation asked evaluators to judge the accuracy, completeness, consistency, functionality and usefulness of IPL metadata fields. Qualitative feedback from evaluators provided us an in depth picture of the IPL metadata quality. We also compared results from the automatic evaluation and the human evaluation.
Delineating the boundary of “context” in information behavior: Towards a contextual identity framework
Authors: Agarwal Naresh Kumar , Xu Yunjie (Calvin) , Poo Danny C.C.
Published: January 2010

Despite the seemingly widespread and growing attention to the notion of ‘context’ in information seeking, the concept remains ill‐defined and inconsistently applied. There isn't any success in defining: What context really means? What are the boundaries of context? What constitutes the ‘core’ (main factors that lead to information seeking behavior) and what constitutes the ‘surrounding’ circumstances (or context)? Where do we draw the line between this core and the context? Or does this context subsume the core? The contribution of this theoretical study will be to help towards delineating the boundaries of context through a Contextual Identity Framework, where we apply the sociological notions of identity, personal identity, social identity and stereotype. The framework has 3 components: 1) Personal Context or ‘my’ context, 2) Shared Context or ‘our’ context, and 3) Context Stereotype or ‘his/her/their’ context. Through this framework, we highlight the futility of trying to define context using any one view. It is only when we take all the 3 views of context into consideration that we are able to adequately define, understand and study context. We hope the framework will provide a basis to further theoretical research in the meaning, role and boundary of context in information behavior.
Take your time first, time your search later: How college students perceive time in Web searching
Authors: Chen Shu‐Yi (Max) , Rieh Soo Young
Published: January 2010

This study explores people's perception of time during their Web searches. Time is a major component of the context for information behavior, but in empirical studies it has been implied rather than investigated explicitly. The data were collected from Web search experiments in which participants were asked to conduct searches on three given tasks under differing search time conditions. The paper reports on findings drawn primarily from the exit interviews of 45 undergraduate and graduate students on their perception of time in Web searching. Study results indicate that at the beginning of their searching activity, participants did not explicitly consider temporal issues. However, these issues usually surface with the passage of time, especially when searches fail to go as planned. Perception of time is closely entangled with familiarity and difficulty of search task. In general, participants enjoyed spending time in searching and were not excessively concerned about time constraints. On the other hand, participants' affective experiences were sometimes caused by temporal issues. In conclusion, the study results indicate that temporal issues interlace with other contextual and affective factors in the process of Web searching.
Internet RFCs as social policy: Network design from a regulatory perspective
Authors: Braman Sandra
Published: January 2010

The Internet has come to fill centrally important economic, social, political, and cultural functions during a period in which policy‐making, too, has been undergoing significant change. The Internet “Requests for Comments” (RFC) process is both the venue technical decision‐making and for the development of Internet governance procedures and institutions. Because this process casts decisions in technical terms, it has largely been without policy scrutiny. This paper offers a preliminary analysis of the RFC discourse for ways in its decision‐making contributes to, operationalizes, influences, or conflicts with the laws of geopolitically recognized governments, and for ways in which the discourse itself serves as the means through which the more formal institutions and practices of Internet governance developed. The paper opens with a discussion of the gap between the technical and legal Internet discourse communities. Policy functions filled by Internet RFCs include explicit policy‐making, explicit policy analysis, and implicit policy analysis (insights into policy issues that are not expressly discussed but that can be elicited from the texts through policy analysis). As a discourse matrix, the RFCs have several features that enable the conversation to fill additional policy‐related functions that include defining the policy subject (the Internet), establishment of Internet design processes, policy implementation programs, conflict and conflict resolution, informal problem resolution, and political analysis.