bluuebunny/crossref_metadata_2025 huggingface dataset:
Fish, Mercury, Selenium and Cardiovascular Risk: Current Evidence and Unanswered Questions
Authors: Mozaffarian Dariush
Published: June 2009

Controversy has arisen among the public and in the media regarding the health effects of fish intake in adults. Substantial evidence indicates that fish consumption reduces coronary heart disease mortality, the leading cause of death in developed and most developing nations. Conversely, concerns have grown regarding potential effects of exposure to mercury found in some fish. Seafood species are also rich in selenium, an essential trace element that may protect against both cardiovascular disease and toxic effects of mercury. Such protective effects would have direct implications for recommendations regarding optimal selenium intake and for assessing the potential impact of mercury exposure from fish intake in different populations. Because fish consumption appears to have important health benefits in adults, elucidating the relationships between fish intake, mercury and selenium exposure, and health risk is of considerable scientific and public health relevance. The evidence for health effects of fish consumption in adults is reviewed, focusing on the strength and consistency of evidence and relative magnitudes of effects of omega-3 fatty acids, mercury, and selenium. Given the preponderance of evidence, the focus is on cardiovascular effects, but other potential health effects, as well as potential effects of polychlorinated biphenyls and dioxins in fish, are also briefly reviewed. The relevant current unanswered questions and directions of further research are summarized.
Inactivation and Unfolding of the Hyperthermophilic Inorganic Pyrophosphatase from Thermus thermophilus by Sodium Dodecyl Sulfate
Authors: Mu Hang , Zhou Sheng-Mei , Xia Yong , Zou Hechang , Meng Fanguo , Yan Yong-Bin
Published: June 2009

Inorganic pyrophosphatase (PPase, EC 3.6.1.1) is an essential constitutive enzyme for energy metabolism and clearance of excess pyrophosphate. In this research, we investigated the sodium dodecyl sulfate (SDS)-induced inactivation and unfolding of PPase from Thermus thermophilus (T-PPase), a hyperthermophilic enzyme. The results indicated that like many other mesophilic enzymes, T-PPase could be fully inactivated at a low SDS concentration of 2 mM. Using an enzyme activity assay, SDS was shown to act as a mixed type reversible inhibitor, suggesting T-PPase contained specific SDS binding sites. At high SDS concentrations, T-PPase was denatured via a two-state process without the accumulation of any intermediate, as revealed by far-UV CD and intrinsic fluorescence. A comparison of the inactivation and unfolding data suggested that the inhibition might be caused by the specific binding of the SDS molecules to the enzyme, while the unfolding might be caused by the cooperative non-specific binding of SDS to T-PPase. The possible molecular mechanisms underlying the mixed type inhibition by SDS was proposed to be caused by the local conformational changes or altered charge distributions.
Protease Inhibitors from Plants with Antimicrobial Activity
Authors: Kim Jin-Young , Park Seong-Cheol , Hwang Indeok , Cheong Hyeonsook , Nah Jae-Woon , Hahm Kyung-Soo , Park Yoonkyung
Published: June 2009

Antimicrobial proteins (peptides) are known to play important roles in the innate host defense mechanisms of most living organisms, including plants, insects, amphibians and mammals. They are also known to possess potent antibiotic activity against bacteria, fungi, and even certain viruses. Recently, the rapid emergence of microbial pathogens that are resistant to currently available antibiotics has triggered considerable interest in the isolation and investigation of the mode of action of antimicrobial proteins (peptides). Plants produce a variety of proteins (peptides) that are involved in the defense against pathogens and invading organisms, including ribosome-inactivating proteins, lectins, protease inhibitors and antifungal peptides (proteins). Specially, the protease inhibitors can inhibit aspartic, serine and cysteine proteinases. Increased levels of trypsin and chymotrypsin inhibitors correlated with the plants resistance to the pathogen. Usually, the purification of antimicrobial proteins (peptides) with protease inhibitor activity was accomplished by salt-extraction, ultrafiltration and C18 reverse phase chromatography, successfully. We discuss the relation between antimicrobial and anti-protease activity in this review. Protease inhibitors from plants potently inhibited the growth of a variety of pathogenic bacterial and fungal strains and are therefore excellent candidates for use as the lead compounds for the development of novel antimicrobial agents.
Improving Temporal Coverage of an Energy-Efficient Data Extraction Algorithm for Environmental Monitoring Using Wireless Sensor Networks
Authors: Chatterjea Supriyo , Havinga Paul
Published: June 2009

Collecting raw data from a wireless sensor network for environmental monitoring applications can be a difficult task due to the high energy consumption involved. This is especially difficult when the application requires specialized sensors that have very high energy consumption, e.g. hydrological sensors for monitoring marine environments. This paper introduces a technique for reducing energy consumption by minimizing sensor sampling operations. In addition, we illustrate how a randomized algorithm can be used to improve temporal coverage such that the time between the occurrence of an event and its detection can be minimized. We evaluate our approach using real data collected from a sensor network deployment on the Great Barrier Reef.
Implanted Mouse Bone Marrow-Derived Cells Reconstruct Layered Smooth Muscle Structures in Injured Urinary Bladders
Authors: Imamura Tetsuya , Kinebuchi Yoshiaki , Ishizuka Osamu , Seki Satoshi , Igawa Yasuhiko , Nishizawa Osamu
Published: June 2009

This study is a preliminary investigation to determine if bone marrow-derived cells, when implanted into freeze-injured urinary bladders, differentiate into smooth muscle cells and reconstruct smooth muscle layers. Bone marrow cells were harvested from femurs of male ICR mice and cultured in collagen-coated dishes for 7 days. After 5 days of culture, the cells were transfected with green fluorescent protein (GFP) genes for identification in recipient tissues. Three days prior to implantation, the posterior urinary bladder walls of female nude mice were injured with an iron bar refrigerated by dry ice. Seven days after the culture and 3 days after the injury, adherent, proliferating GFP-labeled bone marrow-derived cells (1.0 × 105 cells) were implanted into the injured regions. For controls, a cell-free solution was injected. At 14 days after implantation, the experimental urinary bladders were analyzed by histological, gene expression, and cystometric investigations. Just prior to implantation, the injured regions did not have any smooth muscle layers. After 14 days, the implanted cells surviving in the recipient tissues were detected with GFP antibody. The implanted regions had distinct smooth muscle layers composed of regenerated smooth muscle marker-positive cells. The implanted GFP-labeled cells differentiated into smooth muscle cells that formed into layers. The differentiated cells contacted each other within the implanted region as well as smooth muscle cells of the host. As a result, the reconstructed smooth muscle layers were integrated into the host tissues. Control mice injected with cell-free solution developed only few smooth muscle cells and no layers. Cystometric investigations showed that mice with implanted the cells developed bladder contractions similar to normal mice, whereas control mice did not. In summary, mouse bone marrow-derived cells can reconstruct layered smooth muscle structures in injured bladders to remediate urinary dysfunction.
Cultured Melanocytes: From Skin Biopsy to Transplantation
Authors: Ghosh Deepa , Shenoy Sudheer , Kuchroo Pushpa
Published: June 2009

Restoration of cutaneous pigmentation has been achieved in stable vitiligo by autologous melanocyte transplantation. This study was aimed to develop a methodology to deliver melanocytes to vitiliginous area following their processing and culture in a centralized facility. Here we report a methodology to culture melanocytes on carrier films, transport the cells, and graft them on vitiliginous areas. The salient features of this study include: 1) development of polylactic acid (PLA) films that support melanocyte attachment, growth, and delivery; 2) establish transport conditions for skin biopsies from hospitals; 3) establish transport conditions for cultured cells from cell processing center to hospitals. Results suggest that PLA films could serve as carriers for melanocytes during transport. “Upside-down” application of the graft results in the migration of cells from the films into the dermabraded area. The transport conditions ensure cell viability for 96 h. This system could help clinicians, who do not have access to cell culture facilities, transplant cultured melanocytes in a cost-effective manner.
Bioengineering Neural Stem/Progenitor Cell-Coated Tubes for Spinal Cord Injury Repair
Authors: Zahir Tasneem , Nomura Hiroshi , Guo Xiao Dong , Kim Howard , Tator Charles , Morshead Cindi , Shoichet Molly
Published: June 2009

The aim of this study was to understand the survival and differentiation of neural stem/progenitor cells (NSPCs) cultured on chitosan matrices in vivo in a complete transection model of spinal cord injury. NSPCs were isolated from the subependyma of lateral ventricles of adult GFP transgenic rat forebrains. The GFP-positive neurospheres were seeded onto the inner lumen of chitosan tubes to generate multicellular sheets ex vivo. These bioengineered neurosphere tubes were implanted into a completely transected spinal cord and assessed after 5 weeks for survival and differentiation. The in vivo study showed excellent survival of NSPCs, as well as differentiation into astrocytes and oligodendrocytes. Importantly, host neurons were identified in the tissue bridge that formed within the chitosan tubes and bridged the transected cord stumps. The excellent in vivo survival of the NSPCs coupled with their differentiation and maintenance of host neurons in the regenerated tissue bridge demonstrates the promise of the chitosan tubes for stem cell delivery and tissue regeneration.
Murine Embryonic Stem Cell-Derived Hepatic Progenitor Cells Engraft in Recipient Livers with Limited Capacity of Liver Tissue Formation
Authors: Sharma Amar Deep , Cantz Tobias , Vogel Arndt , Schambach Axel , Haridass Dhivya , Iken Markus , Bleidißel Martina , Manns Michael P. , Schöler Hans R. , Ott Michael
Published: June 2009

Directed endodermal differentiation of murine embryonic stem (ES) cells gives rise to a subset of cells with a hepatic phenotype. Such ES cell-derived hepatic progenitor cells (ES-HPC) can acquire features of hepatocytes in vitro, but fail to form substantial hepatocyte clusters in vivo. In this study, we investigated whether this is due to inefficient engraftment or an immature phenotype of ES-HPC. ES cells engrafted into recipient livers of NOD/SCID mice with a similar efficacy as adult hepatocytes after 28 days. Because transplanted unpurified ES-HPC formed teratomas in the spleen and liver, we applied an albumin promoter/enhancer-driven reporter system to purify ES-HPC by cell sorting. RT-PCR analyses for hepatocyte-specific genes showed that the cells exhibited a hepatic phenotype, lacking the expression of the pluripotency marker Oct4, comparable to cells of day 11.5 embryos. Sorted ES-HPC derived from β-galactosidase transgenic ES cells were injected into fumaryl-acetoacetate-deficient (FAH-/-) SCID mice and analyzed after 8 to 12 weeks. Staining with X-gal solution revealed the presence of engrafted cells throughout the liver. However, immunostaining for the FAH protein indicated hepatocyte formation at a very low frequency, without evidence for large hepatocyte cluster formation. In conclusion, the limited repopulation capacity of ES-HPC is not caused by a failure of primary engraftment, but may be due to an immature hepatic phenotype of the transplanted ES-HPC.
Bone Marrow Mesenchymal Stem Cells from Healthy Donors and Sporadic Amyotrophic Lateral Sclerosis Patients
Authors: Ferrero Ivana , Mazzini Letizia , Rustichelli Deborah , Gunetti Monica , Mareschi Katia , Testa Lucia , Nasuelli Nicola , Oggioni Gaia Donata , Fagioli Franca
Published: June 2009

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease lacking effective therapies. Cell replacement therapy has been suggested as a promising therapeutic approach for multiple neurodegenerative diseases, including motor neuron disease. We analyzed expanded mesenchymal stem cells (MSCs) isolated from sporadic ALS patients and compared them with MSCs isolated from healthy donors. MSCs were isolated from bone marrow by Percoll gradient and maintained in culture in MSC Medium until the third passage. Growth kinetics, immunophenotype, telomere length, and karyotype were evaluated during in vitro expansion. Osteogenic, adipogenic, chondrogenic, and neurogenic differentiation potential were also evaluated. No morphological differences were observed in the MSCs isolated from donors or patients. The cellular expansion potential of MSCs from donors and patients was slightly different. After three passages, the MSCs isolated from donors reached a cumulative population doubling higher than from patients but the difference was not statistically significant. No significant differences between donors or patients were observed in the immunophenotype analysis. No chromosomal alteration or evidence of cellular senescence was observed in any samples. Both donor and patient MSCs, after exposure to specific conditioning media, differentiated into adipocytes, osteoblasts, chondrocytes, and neuron-like cells. These results suggest that extensive in vitro expansion of patient MSCs does not involve any functional modification of the cells, including chromosomal alterations or cellular senescence. Hence, there is a good chance that MSCs might be used as a cell-based therapy for ALS patients.
Prenatal Tolerance Induction: Relationship between Cell Dose, Marrow T-Cells, Chimerism, and Tolerance
Authors: Chen Jeng-Chang , Chang Ming-Ling , Huang Shiu-Feng , Chang Pei-Yeh , Muench Marcus O. , Fu Ren-Huei , Ou Liang-Shiou , Kuo Ming-Ling
Published: June 2009

It was reported that the dose of self-antigens can determine the consequence of deletional tolerance and donor T cells are critical for tolerance induction in mixed chimeras. This study aimed at assessing the effect of cell doses and marrow T cells on engraftment and tolerance induction after prenatal bone marrow transplantation. Intraperitoneal cell transplantation was performed in FVB/N (H-2Kq) mice at gestational day 14 with escalating doses of adult C57BL/6 (H-2Kb) marrows. Peripheral chimerism was examined postnatally by flow cytometry and tolerance was tested by skin transplantation. Transplantation of light-density marrow cells showed a dose response. High-level chimerism emerged with a threshold dose of 5.0 × 106 and host leukocytes could be nearly replaced at a dose of 7.5–10.0 × 106. High-dose transplants conferred a steady long-lasting donor-specific tolerance but were accompanied by >50% incidence of graft-versus-host disease. Depletion of marrow T cells lessened graft-versus-host disease to the detriment of engraftment. With low-level chimerism, tolerance was a graded phenomenon dependent upon the level of chimerism. Durable chimerism within 6 months required a threshold of = 2% chimerism at 1 month of age and predicted a 50% chance of long-term tolerance, whereas transient chimerism (<2%) only caused hyporesponsiveness to the donor. Tolerance induction did not succeed without peripheral chimerism even if a large amount of injected donor cells persisted in the peritoneum. Neither did an increase in cell doses or donor T-cell contents benefit skin graft survivals unless it had substantially improved peripheral chimerism. Thus, peripheral chimerism level can be a simple and straightforward test to predict the degree of prenatal immune tolerance.
Electrical Stimulation-Induced Release of β-Endorphin from Genetically Modified Neuro-2a Cells
Authors: Storn Volker , Kirschbaum Michael , Schlosshauer Burkhard , Mack Andreas F. , Fricke Cornelia
Published: June 2009

The quantity of therapeutic gene products released from genetically engineered cells can be controlled externally at different levels. The widely used approach of controlling expression, however, generally has the disadvantage that chemical substances must be applied for stimulation. An alternative strategy aims at controlling gene products at posttranslational levels such as secretion. The secretion of a therapeutic agent can be regulated if the agent is targeted to the regulated secretory pathway and stored in the secretory granules until its release. In this article we address the question of whether the release of β-endorphin, an opioid with a potent analgesic effect, could be induced by electrically stimulating stably transfected Neuro-2a cells. Throughout this study we used the human proopiomelanocortin (POMC) gene, which is the precursor molecule for human β-endorphin. We analyzed its subcellular localization and found it in the regulated secretory pathway in Neuro-2a cells. Using electrical field stimulation we were able to identify a stimulation pattern that significantly increased the release of β-endorphin-immunoreactive material, although to a limited extent. This result indicates that electrical stimulation of secretion could be used to manipulate the amount of a therapeutic agent released from transplanted cells.
A Rat Embryo Staging Scale for the Generation of Donor Tissue for Neural Transplantation
Authors: Torres E. M. , Weyrauch U. M. , Sutcliffe R. , Dunnett S. B.
Published: June 2009

In rat models of Parkinson's and Huntington's diseases, embryonic neural cells obtained from embryos of specified ages can be implanted into the brain to partially restore both physiology and function. However, in litters produced using overnight mating protocols (often from commercial suppliers), the embryonic age can be difficult to determine precisely. As a result, embryonic size based on crown to rump length (CRL) is usually a more reliable method of embryo staging than the day of mating. This approach is not without difficulty. There are a number of rat staging scales in the literature, none of which deal with donor ages younger than E13, and there are discrepancies between scales at some donor ages. In the present article, we have devised a short mating-period protocol to produce precisely aged embryos. We show that CRL is a highly accurate, reproducible index of donor age and we present an updated embryonic staging scale for Sprague-Dawley (CD) rats that includes donor ages younger than those previously reported.
Sertoli Cell Line Lacks the Immunoprotective Properties Associated with Primary Sertoli Cells
Authors: Dufour Jannette M. , Dass Brinda , Halley Katie R. , Korbutt Gregory S. , Dixon Doreen E. , Rajotte Ray V.
Published: June 2009

Sertoli cells are important for maintenance of the immune privileged environment of the testis and prolong survival of cotransplanted cells. The objective of the current study was to examine the immunoprotective properties of a mouse Sertoli cell line (MSC-1) in order to identify a Sertoli cell line that could be used to aid in investigation of the immunoprotective abilities of Sertoli cells. BALB/c islets were cotransplanted with 0–9 million primary BALB/c Sertoli cells or MSC-1 cells into diabetic C3H or BALB/c mice and protection of grafted islets was examined by monitoring blood glucose levels and immunohistochemical analysis. Additionally, expression of potential immunoprotective factors in MSC-1 cells was examined. Cotransplantation of islets with 3 million primary Sertoli cells significantly prolonged islet allograft survival (61.1 ± 6.9 days; p < 0.05) compared with control mice that received allogeneic islets alone (26.9 ±2.1 days). Grafts collected from normoglycemic C3H mice at 100 days posttransplant contained insulin-positive β-cells adjacent to allogeneic Sertoli cells arranged in tubule-like structures. In contrast, cotransplantation of islet allografts with MSC-1 cells did not prolong islet survival (average 29.8 ± 3.3 days) regardless of the number of MSC-1 cells transplanted and the rejected grafts contained very few β-cells and randomly arranged MSC-1 cells. The lack of islet cell survival was not due to detrimental effects of MSC-1 cells because syngneic islets cotransplanted with MSC-1 cells were functional throughout the study. MSC-1 cells were found to express known Sertoli cell-expressed, immunoprotective factors, clusterin, Fas ligand, and transforming growth factor-β1, suggesting additional factors may be involved in Sertoli cell immune privilege. These data indicate the MSC-1 cell line lacks the immunoprotective properties associated with primary Sertoli cells. Further study of this cell line could be useful in examining the mechanisms that enable Sertoli cells to provide immune privilege.
Autologous Bone Marrow Cell Transplantation Increases Leg Perfusion and Reduces Amputations in Patients with Advanced Critical Limb Ischemia Due to Peripheral Artery Disease
Authors: Amann Berthold , Luedemann Claas , Ratei Richard , Schmidt-Lucke J. André
Published: June 2009

Bone marrow cell transplantation has been shown to induce angiogenesis and thus improve ischemic artery disease. This study evaluates the effects of intramuscular bone marrow cell transplantation in patients with limb-threatening critical limb ischemia with a very high risk for major amputation. After failed or impossible operative and/or interventional revascularization and after unsuccessful maximum conservative therapy, 51 patients with impending major amputation due to severe critical limb ischemia had autologous bone marrow cells (BMC) transplanted into the ischemic leg. Patients 1–12 received Ficoll-isolated bone marrow mononuclear cells (total cell number 1.1 ± 1.1 × 109), patients 13–51 received point of care isolated bone marrow total nucleated cells (3.0 ± 1.7 × 109). Limb salvage was 59% at 6 months and 53% at last follow-up (mean 411 ± 261 days, range 175–1186). Perfusion measured with ankle-brachial index (ABI) and transcutaneous oxygen tension (tcpO2) at baseline and after 6 months increased in patients with consecutive limb salvage (ABI 0.33 ± 0.18 to 0.46 ± 0.15, tcpO2 12 ± 12 to 25 ± 15 mmHg) and did not change in patients eventually undergoing major amputation. No difference in clinical outcome between the isolation methods were seen. Clinically most important, patients with limb salvage improved from a mean Rutherford category of 4.9 at baseline to 3.3 at 6 months ( p = 0.0001). Analgesics consumption was reduced by 62%. Total walking distance improved in nonamputees from zero to 40 m. Three severe periprocedural adverse events resolved without sequelae, and no unexpected long-term adverse events occurred. In no-option patients with end-stage critical limb ischemia due to peripheral artery disease, bone marrow cell transplantation is a safe procedure that can improve leg perfusion sufficiently to reduce major amputations and permit durable limb salvage.
Autologous Bone-Marrow Mononuclear Cell Transplantation after Acute Myocardial Infarction: Comparison of Two Delivery Techniques
Authors: Silva Suzana A. , Sousa André L. S. , Haddad Andrea F. , Azevedo Jader C. , Soares Vinicio E. , Peixoto Cíntia M. , Soares Ana J. S. , Issa Aurora F. C. , Felipe Luis Renato V. , Branco Rodrigo V. C. , Addad João A. , Moreira Rodrigo C. , Tuche Fabio A. A. , Mesquita Cláudio T. , Drumond Cristina C. O. , Junior Amarino O. , Rochitte Carlos E. , Luz José H. M. , Rabischoffisky Arnaldo , Nogueira Fernanda B. , Vieira Rosana B. C. , Junior Hamilton S. , Borojevic Radovan , Dohmann Hans F. R.
Published: June 2009

The objective of this study was to investigate safety and feasibility of autologous bone marrow mononuclear cells (BMMNC) transplantation in ST elevation myocardial infarction (STEMI), comparing anterograde intracoronary artery (ICA) delivery with retrograde intracoronary vein (ICV) approach. An open labeled, randomized controlled trial of 30 patients admitted with STEMI was used. Patients were enrolled if they 1) were successfully reperfused within 24 h from symptoms onset and 2) had infarct size larger than 10% of the left ventricle (LV). One hundred million BMMNC were injected in the infarct-related artery (intra-arterial group) or vein (intravenous group), 1% of which was labeled with Tc99m-hexamethylpropylenamineoxime. Cell distribution was evaluated 4 and 24 h after injection. Baseline MRI was performed in order to evaluate microbstruction pattern. Baseline radionuclide ventriculography was performed before cell transfer and after 3 and 6 months. All the treated patients were submitted to repeat coronary angiography after 3 months. Thirty patients (57 ± 11 years, 70% males) were randomly assigned to ICA ( n = 14), ICV ( n = 10), or control ( n = 6) groups. No serious adverse events related to the procedure were observed. Early and late retention of radiolabeled cells was higher in the ICA than in the ICV group, independently of microcirculation obstruction. An increase of EF was observed in the ICA group ( p = 0.02) compared to baseline. Injection procedures through anterograde and retrograde approaches seem to be feasible and safe. BMMNC retention by damaged heart tissue was apparently higher when the anterograde approach was used. Further studies are required to confirm these initial data.
NF-κB Activity in Endothelial Cells is Modulated by Cell Substratum Interactions and Influences Chemokine-Mediated Adhesion of Natural Killer Cells
Authors: Hess Shmuel , Methe Heiko , Kim Jong-Oh , Edelman Elazer R.
Published: June 2009

Because changes in subendothelial matrix composition are associated with alterations of the endothelial immune phenotype, we sought to understand if cytokine-induced NF-κB activity and downstream effects depend on substrate adherence of endothelial cells (EC). We compared the upstream phosphorylation cascade, activation of NF-κB, and expression/secretion of downstream effects of EC grown on tissue culture polystyrene plates (TCPS) with EC embedded within collagen-based matrices (MEEC). Adhesion of natural killer (NK) cells was quantified in vitro and in vivo. NF-κB subunit p65 nuclear levels were significantly lower and p50 significantly higher in cytokine-stimulated MEEC than in EC-TCPS. Despite similar surface expression of TNF-α receptors, MEEC had significantly decreased secretion and expression of IL-6, IL-8, MCP-1, VCAM-1, and ICAM-1. Attenuated fractalkine expression and secretion in MEEC (two to threefold lower than in EC-TCPS; p < 0.0002) correlated with 3.7-fold lower NK cell adhesion to EC (6,335 ± 420 vs. 1,735 ± 135 cpm; p < 0.0002). Furthermore, NK cell infiltration into sites of EC implantation in vivo was significantly reduced when EC were embedded within matrix. Matrix embedding enables control of EC substratum interaction. This in turn regulates chemokine and surface molecule expression and secretion, in particular of those compounds within NF-κB pathways, chemoattraction of NK cells, local inflammation, and tissue repair.
Function and Mode of Regulation of Endothelial Major Histocompatibility Complex Class II
Authors: Alexander Irina , Edelman Elazer R. , Methe Heiko
Published: June 2009

Tissue engineering is a promising approach to implement endothelial cells as a cellular delivery therapy for vascular disease. We and others previously demonstrated that endothelial cells embedded in three-dimensional collagen-based matrices retain their full biosecretory spectrum, enabling them to serve as powerful regulators of vascular diseases. Fascinatingly, matrix embedding of endothelial cells not only allows for their implantation but also seems to provide protection from allo- and xenogeneic-triggered host immune responses. This is not an effect of simple physical shielding but a more fundamental influence of cell–matrix interconnectivity on the cellular immune phenotype. Reduced cytokine-induced levels of costimulatory and adhesion molecules associated with significantly lower expression levels of major histocompatibility class II expression on matrix-embedded human aortic endothelial cells when compared to the same cells cultured on two-dimensional polystyrene coated-tissue culture plates. Strikingly, the entire interferon-γ-dependent signaling cascade resulting in MHC class II molecule expression is markedly suppressed in endothelial cells grown to confluence within three-dimensional scaffolds. These findings might be of pivotal importance for designing endothelial cell-based therapies in general and might enhance our understanding of the underlying pathophysiology in a broad range of cardiovascular diseases (e.g., atherosclerosis, vasculitis, chronic allograft vasculopathy).
La teoría del actor-red y la tesis de la tecnociencia
Authors: Echeverría Javier , González Marta I.
Published: June 2009

La teoría del actor-red y el análisis de la tecnociencia desarrollado por Javier Echeverría (2003) presentan múltiples puntos comunes, pero también importantes divergencias. Mientras que el análisis de la tecnociencia responde al intento filosófico de clasificar y caracterizar las modalidades de práctica científico-tecnológica contemporánea, el conjunto de herramientas metodológicas de la teoría del actor-red trae al primer plano el desorden oculto tras la ordenada apariencia de la tecnociencia, la contemporánea y la de épocas pasadas. Sin embargo, la teoría del actor-red se muestra útil para describir las complejas redes tejidas por centros de investigación, instituciones, universidades y empresas, y los productos resultantes de las mismas en términos de orden natural y social. En este trabajo caracterizamos someramente tanto la teoría del actorred como la tecnociencia, para identificar de qué modo ambas, pese a sus diferencias, pueden beneficiarse mutuamente.
El modelo de Triple Hélice de relaciones universidad, industria y gobierno: un análisis crítico
Authors: González de la Fe Teresa
Published: June 2009

Se revisará el modelo de Triple Hélice de relaciones entre universidad, industria y gobierno, ampliamente usado en los estudios de la innovación. Impulsado por Etzkowitz y Leyersdorf, el modelo ha resultado fructífero como heurística para el análisis de los procesos de innovación y como esquema normativo para políticas de innovación. Además, los fundamentos teóricos del modelo casan bien con los enfoques de las teorías evolucionista e institucionalista en economía, al tiempo que toman en cuenta variables sociológicas tradicionalmente descuidadas por la teoría económica. Por otro lado, la acumulación de conocimiento en torno a experiencias de triples hélices durante más de una década ha mostrado que el modelo sirve como impulsor de innovaciones no sólo destinadas al mercado sino también a diferentes problemas sociales. Pese a ello, ha suscitado críticas que señalan sus funciones legitimadoras y sus debilidades para la descripción y la explicación de los complejos procesos de las innovaciones.
Ciencia y economía
Authors: Barge-Gil Andrés , Modrego Rico Aurelia
Published: June 2009

La relación entre ciencia y economía es un tema de gran actualidad, atrae la atención tanto en el mundo científico como en el empresarial y el político. El principal objetivo de este trabajo consiste en mostrar de forma sintética el estado del arte sobre esta cuestión. Para ello, se presenta el análisis de la ciencia realizado por los economistas, prestando especial atención a las controversias existentes entre la perspectiva neoclásica y evolucionista, se repasa la evidencia empírica existente a partir de trabajos de muy distinta naturaleza y se resumen las líneas principales del debate actual acerca el modelo de organización de la ciencia. Las principales conclusiones del estudio muestran que ciencia y economía se hallan íntimamente relacionadas y que sus vínculos son complejos y dinámicos, por lo que se requieren planteamientos flexibles en la gestión y evaluación de dicha relación.
Estrategias de adquisición de conocimiento en los procesos de innovación empresarial
Authors: Vega-Jurado Jaider , Gutiérrez-Gracia Antonio , Fernández-de-Lucio Ignacio
Published: June 2009

El reconocimiento de los agentes externos como una fuente importante de conocimiento para el desarrollo de los procesos de innovación ha hecho que las empresas tengan que hacer frente a una decisión importante: generar o adquirir externamente el conocimiento tecnológico que precisan. Debido a sus implicaciones, esta decisión se ha convertido en un tema de creciente interés entre los académicos y estudiosos de la innovación, propiciando el desarrollo de toda una literatura, teórica y empírica, sobre los factores y motivaciones que inciden en la misma. En este artículo se presenta una revisión de esta literatura, a partir del análisis de tres estrategias de innovación (hacer, comprar y cooperar) y considerando las aportaciones derivadas de la teoría económica de los costes de transacción y de los enfoques basados en las capacidades de la empresa.
Enfoques positivos y normativos en las políticas de ciencia y tecnología
Authors: Rico-Castro Pilar , Morera Cuesta Rafael
Published: June 2009

Este artículo presenta una visión general de la evolución de los trabajos que estudian las políticas públicas de investigación científica y desarrollo tecnológico (I+D), desde la apertura de este campo a la acción del gobierno en la década de 1940 hasta la actualidad. Tras hacer un repaso descriptivo de cuáles fueron las primeras aportaciones de los decisores públicos y de los académicos a este campo de conocimiento durante su proceso de creación, este trabajo utiliza la distinción entre enfoques positivos y normativos y defiende que el liderazgo normativo ha correspondido a los organismos internacionales, especialmente a la OCDE, y que los enfoques positivos en la literatura académica internacional y en la nacional han evolucionado siguiendo las pautas marcadas por esta institución.
La teoría de principal-agente en los estudios sobre ciencia y tecnología
Authors: Fernández-Carro Remo
Published: June 2009

Este trabajo presenta la Teoría de Principal-Agente y la forma en que se ha establecido en los últimos años en los estudios de ciencia y tecnología. Para ello describe, primero, la propia teoría y la forma en que la han desarrollado la economía y la ciencia política. El trabajo revisa el modo en que estas disciplinas la han utilizado para explicar problemas relacionados con ciencia y tecnología o que los tocan lateralmente. Después se ocupa de las aplicaciones concretas en los llamados estudios de ciencia y tecnología. El artículo propone que la teoría se relaciona con las teorías clásicas de la disciplina, de las que a veces es sólo una formalización. Como propone, por fin, que las debilidades de la teoría se deben antes a su mal uso y a su escaso desarrollo que a sus posibilidades reales, a juzgar por su éxito en otras ciencias sociales.
La naturaleza del «conocimiento objetivo»: algunas reflexiones en torno a la ciencia y su contexto social
Authors: Carbonell Eudald , Hortolà Policarp
Published: June 2009

En este artículo, los autores exponen cómo el contexto histórico marca diacrónicamente cada nueva concepción de lo que es “conocimiento objetivo” y, en consecuencia, de lo que es “ciencia”. Para ello, los autores hacen una serie de reflexiones sobre el valor epistémico del conocimiento objetivo en tanto que conocimiento de la realidad más digno de confianza en un momento histórico dado, sobre el carácter indisociable del binomio ciencia-científicos, el problema epistemológico de establecer mecanismos de “objetivización” de la capacidad de las ciencias para generar conocimiento y la relación existente entre ciencia e ideología.
La investigación teórica sobre la divulgación de la ciencia en España: situación actual y retos para el futuro
Authors: González-Alcaide Gregorio , Valderrama-Zurián Juan Carlos , Aleixandre-Benavent Rafael
Published: June 2009

Se analiza la producción científica española sobre divulgación de la Ciencia como objeto de investigación, identificando los principales agentes científicos, canales de difusión y ámbitos abordados. Se trata de un campo enormemente heterogéneo en el que confluyen diversas disciplinas científicas y propósitos, sobresaliendo los de informar y educar. Se han analizado 286 artículos de revista y 50 tesis doctorales. A partir de la década de los noventa es cuando se produce la eclosión de la investigación, multiplicándose el número de trabajos hasta la actualidad. Se han identificado cinco destacados núcleos temáticos de investigación: periodismo científico, alfabetización científica, lingüística, la divulgación como actividad cultural en el ámbito museístico y la investigación relacionada con determinadas disciplinas, como la Medicina, el Medio Ambiente o la Arqueología.
Autopoiesis, bucles, emergencia, variedades topológicas y una conjetura sobre la consciencia humana
Authors: Sarmiento Campos José A.
Published: June 2009

La presente reflexión pretende ser un acercamiento plausible al concepto de consciencia y propone una explicación a su surgimiento. Varias de las aportaciones que diversos autores han hecho a la ciencia y que conforman el paradigma de la complejidad, como son los conceptos de sistema, autopoiesis, emergencia, cibernética de primer y segundo orden o estado crítico; junto con otros de naturaleza matemática como las variedades topológicas n-dimensionales y aun otros procedentes de la biología como redes neuronales, capas corticales o distribución columnar de la neocorteza, se pueden integrar en un constructo, que consideramos epistemológicamente sólido, que podría dar una respuesta a cuestiones como la emergencia de la consciencia humana y también, probablemente, social.
Análisis de las principales variables de proceso que influyen en el rechazo de los cátodos durante el electrorrefino del cobre
Authors: Cifuentes G. , Vargas C. , Simpson J.
Published: June 2009

Se trabajó en un circuito experimental de electrorrefinación de cobre, utilizando tres tipos de ánodos procedentes de tres fundiciones chilenas diferentes: Hernán Videla Lira, Las Ventanas y El Teniente. En este circuito, se estudió el problema del rechazo de cátodos y la influencia de algunas variables de proceso en este fenómeno. Las variables analizadas fueron: flujo de electrolito en la celda, sólidos en suspensión, densidad de corriente, dopado de plomo en los ánodos, densidad de los barros anódicos generados y tamaño de partícula de los barros anódicos. Los principales resultados obtenidos a partir del estudio del circuito experimental fueron los siguientes: el flujo de electrolito no afecta significativamente el rechazo de cátodos, a medida que aumenta la densidad de corriente disminuyen los rechazos, el aumento de los sólidos en suspensión provoca cátodos fuera de norma y a mayor cantidad de plomo en los ánodos menores fueron los rechazos.
Influencia de la atmósfera de control y tiempo de molienda sobre la morfología y microestructura de polvos de cobre puro y cobre- 2,5 % litio producidos por aleado mecánico
Authors: Rojas P. A. , Álvarez M. P. , Peñaloza A. , Zúñiga A. , Ordoñez S.
Published: June 2009

En el presente trabajo se investigó el efecto de la atmósfera y el tiempo de molienda sobre las fases, microestructura y composición de polvos de cobre y de una mezcla cobre – 2,5 % litio, sometidas a aleado mecánico. La molienda se realizó en un molino SPEX 8000D empleando contenedores y bolas de acero. Las dos atmósferas estudiadas fueron argón y nitrógeno, y los tiempos de molienda de 3 a 30 h. Los cambios microestructurales y las fases se analizaron mediante microscopía electrónica de barrido y difracción de rayos X, mientras que la composición química se determinó mediante espectroscopía de absorción atómica e infrarroja. Los resultados mostraron el efecto de los parámetros de molienda estudiados en la microestructura y en la composición química de las muestras.
Una estrategia de ecodiseño de piezas obtenidas mediante moldeo a presión: análisis microestructural aplicado a la desmaterialización
Authors: Suárez-Peña B. , Asensio-Lozano J.
Published: June 2009

En este trabajo se estudia la posibilidad de empleo de nuevas aleaciones de aluminio con estructuras micrográficas optimizadas que garanticen mejoras en el comportamiento mecánico de componentes fabricados mediante fundición a presión. El objetivo ha sido explorar la posibilidad de fabricación de ecopeldaños de elevación con destino a escaleras mecánicas, menos reforzados estructuralmente y por tanto más ligeros que los que hasta ahora se venían fabricando. Los resultados experimentales muestran que es factible disminuir el uso de materiales durante la fabricación y reducir, por tanto, el impacto a lo largo de la vida de los componentes, todo ello manteniendo o incluso mejorando las prestaciones en servicio y la seguridad.
Recuperación de cobre en escorias mediante biolixiviación indirecta
Authors: Mazuelos A. , Iglesias N. , Romero R. , Forcat O. , Carranza F.
Published: June 2009

En los procesos pirometalúrgicos, parte del cobre se pierde en la escoria que se genera como residuo del proceso, pudiendo estar presente en ella, en concentraciones muy superiores a las de muchas menas. El cobre se encuentra formando parte de pequeñas partículas de mata, metal blanco y blister, ocluidas en fase de fayalita. En este trabajo se ha probado la viabilidad técnica del proceso BRISA, que está basado en la biolixiviación indirecta, para el tratamiento de este residuo. Se ha caracterizado una escoria con un 2 % en cobre, desde los planos químico, granulométrico y metalográfico. Este material se ha lixiviado con disoluciones de sulfato férrico en reactores agitados, estudiándose el efecto de diversas variables. A partir de los resultados obtenidos, e incluyendo un estudio económico, con resultados muy atractivos, se han seleccionado las mejores condiciones de operación y se ha diseñado la etapa de lixiviación para una planta de 30 t/h de capacidad. En esta planta sería posible alcanzar extracciones de cobre superiores al 70 % con un tiempo de residencia de sólo 5 h. La etapa de biooxidación suministraría el férrico necesario pese a haber presente Cu(II) en el circuito en concentraciones de hasta 30 g/l.
Racionalización de mezclas de minerales de hierro para la obtención de sinterizados de calidad optima
Authors: Cores A. , Ferreira S. , Muñiz M.
Published: June 2009

Se utilizaron diversos minerales de hierro, fundentes y coque para preparar cuatro mezclas minerales con distintas proporciones de estos minerales. Con cada mezcla se fabricó una serie de sinterizados en planta piloto. Se caracteriza cada uno de los sinterizados mediante análisis químico y granulométrico, ensayo de la degradación del sinterizado durante la reducción en el horno alto (ensayo RDI), ensayo de la resistencia en frío (ensayo Tumbler), ensayo de reductibilidad; determinación de las temperaturas de reblandecimiento y fusión y determinación de la estructura del sinterizado por microscopia electrónica. Se establecen las condiciones de las mezclas y los parámetros de operación para la obtención de sinterizados de calidad óptima.
Nuevos aspectos fundamentales y ambientales de la corrosión atmosférica
Authors: Leygraf C.
Published: June 2009

La corrosión atmosférica implica procesos químicos, electroquímicos y físicos en tres fases (sólido, liquido y gas) y dos interfases (sólido/líquido y líquido/gas). A causa de dificultades experimentales y conceptuales los esfuerzos científicos para caracterizar el proceso, interfacial, altamente complejo, han llegado con relativo retraso a este campo científico. Con el acceso y desarrollo de técnicas analíticas de superficie e interfase de gran sensibilidad, ha sido posible últimamente llevar a cabo “in situ” análisis moleculares de las interfases involucradas en la corrosión atmosférica. Este artículo presenta algunos aspectos relevantes de la investigación fundamental llevada a cabo en el Royal Institute of Technology de Estocolmo, Suecia. Incluye resultados de los esfuerzos más recientes de nuestro grupo de investigación para elaborar un retrato del régimen interfacial que gobierna la corrosión atmosférica utilizando cobre o cinc como sustrato y un ácido carboxílico como estimulador de la corrosión en una atmósfera húmeda. Se han obtenido resultados que muestran con especial énfasis la interfase óxido metálico/agua, mediante espectroscopia de infrarrojo de absorción-reflexión (IRAS) combinado con microbalanza de cristal de cuarzo (QCM), y la interfase agua/gas mediante generación de suma de frecuencias (SFG). Mientras que la investigación en corrosión atmosférica tradicionalmente ha incidido en el conocimiento del efecto ambiental en el metal, el aspecto opuesto, es decir, de cómo el metal afecta al medioambiente durante el proceso de corrosión atmosférica, puede ser igualmente de gran importancia técnica. En el trabajo se presentan algunos ejemplos de investigaciones actualmente en marcha sobre nuevos aspectos ambientales de la corrosión atmosférica del cinc.
The Role for T Cell Repertoire/Antigen-Specific Interactions in Experimental Kidney Ischemia Reperfusion Injury
Authors: Satpute Shailesh Ramchandra , Park Jong Myun , Jang Hye Ryoun , Agreda Patricia , Liu Manchang , Gandolfo Maria Teresa , Racusen Lorraine , Rabb Hamid
Published: June 2009

T cells have been implicated in the early pathogenesis of ischemia reperfusion injury (IRI) of kidney, liver, lung, and brain. It is not known whether Ag-TCR engagement followed by Ag-specific T cell activation participates in IRI. T cell-deficient nu/nu mice are moderately resistant to renal IRI, which can be reversed upon reconstitution with syngeneic T cells. In this study, we found that nu/nu mice reconstituted with DO11.10 T cells, limited in their TCR repertoire, have significantly less kidney dysfunction and tubular injury after renal IRI compared with that in nu/nu mice reconstituted with wild-type T cells having a diverse TCR repertoire. CD4+ T cells infiltrating ischemic kidneys of nu/nu mice reconstituted with DO11.10 T cells exhibited lower IFN-γ production than that of wild-type controls. Frequency of regulatory T cells in kidneys of these mice was similar in both DO11.10 T cells and wild-type T cell recipient groups. DO11.10 mice immunized with OVA-CFA had significantly worse kidney function at 24 h after ischemia than those immunized with CFA alone. Thus, without T cell activation, diverse TCR repertoire was important for renal IRI in naive mice. However, once T cells were activated in an Ag-specific manner through TCR in DO11.10 mice, a restricted TCR repertoire no longer limited the extent of kidney injury. Thus, both TCR repertoire-dependent and -independent factors mediate T cell functions in kidney IRI.