bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrochemical Investigation of Metal Sulfides at Mercury Electrodes Using Thiourea as a Source of Sulfide Ion
Authors: Bănică Florinel‐Gabriel , Galík Michal , Švancara Ivan , Vytřas Karel
Published: January 2009

A mercury sulfide layer was prepared at the surface of a mercury electrode by an anodic reaction (+0.1 V vs. Ag|AgCl|KCl(3 M)) in the presence of thiourea at the micromolar concentration level. Electrochemical reactions of mercury sulfide were investigated by a subsequent cathodic scan at near‐neutral pH values and in the absence/presence of a second metal ion. Two different forms of mercury sulfide were evidenced by characteristic cathodic peaks; the first one (in the form of adsorbed molecules) undergoing a reversible reduction at about −0.6 V, whereas the second one (probably as nanoaggregates) being reduced in an irreversible process at −0.9 V. A detailed analysis of the first process was performed by adapting the already existing theoretical approaches. It was proven that the HgS layer prepared by mercury anodization in the presence of thiourea is similar to that prepared by anodization in the presence of sulfide ion. Other metal sulfides were prepared via the exchange reaction of mercury in HgS with a metal ion in solution; namely, Zn2+, Ni2+, and Cd2+; reactions of the latter proceeding in a fair agreement with the theoretical model used (the rapid exchange leading to the single CdS form with no soluble cadmium sulfide species). Evident deviations from this model have occurred with both Ni2+ and Zn2+ due to a sluggish exchange reaction, formation of soluble species, and occurrence of various metal sulfide forms. Two different forms of nickel sulfide were detected by characteristic cathodic reactions, namely i) adsorbed free molecules that are reduced at −1.0 V and are able to take part in a catalytic (EC′) reduction of Ni2+; and ii) an aggregated form that is irreversibly reduced at negative potentials beyond −1.2 V and acts as a catalyst for hydrogen evolution. The method presented herein allows one electrochemical preparation and investigation of metal sulfides with no difficulty due to hydrogen sulfide volatility at pH<12 and emphasizes that this method can be applied to other systems consisting of a chalcogenide anion and a metal (like mercury or silver) being able of undergoing a reversible electrochemical reaction. In addition, this contribution provides an insight to the intricacy of the electrochemical behavior of the mercury electrode/sulfide anion/second metal ion system and mentions a series of sources of errors related to the interpretation of such data obtained with natural water specimens.
Fifty Years of Nucleic Acid Electrochemistry
Authors: Paleček Emil
Published: January 2009

Electrochemistry of nucleic acids (NA's) is a booming field offering sensors for DNA hybridization and DNA damage. Since the middle of the 1990's, when the development of the DNA sensors began, the number of papers in this field is steadily increasing. Electroactivity of DNA and RNA was reported for the first time in 1958. Using oscillographic polarography at controlled AC (OP, AC chronopotentiometry) and a dropping mercury electrode it was shown within several years that OP signals respond to changes in DNA structure and can be used to study DNA denaturation, renaturation, premelting and DNA damage. During the first three decades a number of important findings were done, including introductions of covalently bound electroactive labels in DNA, DNA‐modified electrodes, application of solid electrodes, etc., which are now used in the development of the NA sensors. On the other hand a lot of knowledge obtained in the first three decades has remained largely unknown to the present generation of researchers.
Multicommutated Anodic Stripping Voltammetry at Tubular Bismuth Film Electrode for Lead Determination in Gunshot Residues
Authors: Rodriguez Jose A. , Ibarra Israel S. , Galan‐Vidal Carlos A. , Vega Marisol , Barrado Enrique
Published: January 2009

This work describes the construction of a miniaturized flow‐through electrochemical cell and its application to the determination of lead in gunshot residues (GSR) by differential‐pulse anodic stripping voltammetry at bismuth films co‐deposited on‐line on a tubular carbon paste electrode. The developed detector was coupled to a multicommutated flow system which was designed to allow medium exchange prior to the stripping step thus reducing interferences from the analytical matrix, and to implement the standard additions method in an automatic way, using only one standard solution. For a deposition time of 60 s at −1.5 V at a flow rate of 0.5 mL min−1 without oxygen removal, the detection limit of the method was 0.2 mg L−1. Under these conditions the linear dynamic range was 0.3–10.0 mg L−1 with a sampling rate of 15.0 samples h−1. Repeatability of lead concentration was 3% (n=3). The method was applied to the analysis of lead in GSR on hands of shooters and concentrations up to 16.5 μg and 6.7 μg were found in palms and backs, respectively. No statistically significant differences between the results obtained by the proposed and the comparative method (F‐AAS) were found, at a 95% confidence level.
Metallacarboranes as Labels for Multipotential Electrochemical Coding of DNA. [3‐Chromium bis(dicarbollide)](‐1)ate and Its Nucleoside Conjugates
Authors: Olejniczak Agnieszka B. , Grűner Bohumir , Šicha Václav , Broniarek Sabina , Lesnikowski Zbigniew J.
Published: January 2009

Metallacarborane bearing chromium is proposed as the electrochemical label for electrochemical coding of DNA. Synthesis and HDV characteristics of 2′‐deoxyadenosine (dA) containing [(3,3′‐chromium‐1,2,1′,2′‐dicarbollide)](−1)]ate complex are described. The proposed labeling of nucleosides, together with previously described nucleoside/metallacarborane conjugates bearing cobalt and iron lay the foundations for multipotential electrochemical coding of DNA with metallacarborane complexes and simultaneous detection of several DNA targets.
Novel Protocol for Covalent Immobilization of Horseradish Peroxidase on Gold Electrode Surface
Authors: Radi Abd‐Elgawad , Muñoz‐Berbel Xavier , Cortina‐Puig Montserrat , Marty Jean‐Louis
Published: January 2009

A novel protocol for immobilization of horseradish peroxidase (HRP) onto diazonium functionalized screen‐printed gold electrode (SPGE) has been successfully developed. This protocol involved 1) electrochemical reduction of p‐nitrophenyl diazonium salts synthesized in situ in acidic aqueous solution to graft a layer of p‐nitrophenyl on SPGE, 2) electrochemical reduction of the nitro groups to convert to amines, 3) chemical reaction with nitrous acid to transform the amine to diazonium derivative and 4) chemical coupling of the enzyme with the diazonium group to form a covalent diazo bond. The fabricated biosensor showed the direct electrochemistry of HRP and displayed electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2) without any mediator. The biosensor exhibited fast amperometric response to H2O2. The catalytic current increased with increasing H2O2 concentration from 5 μM to 30 μM and the detection limit of the biosensor was 2 μM. The biosensor exhibited acceptable sensitivity, good reproducibility and long‐term stability.
Changes in hippocampal morphology and neuroplasticity induced by adolescent THC treatment are associated with cognitive impairment in adulthood
Authors: Rubino Tiziana , Realini Natalia , Braida Daniela , Guidi Sandra , Capurro Valeria , Viganò Daniela , Guidali Cinzia , Pinter Marta , Sala Mariaelvina , Bartesaghi Renata , Parolaro Daniela
Published: January 2009

Marijuana and hashish are the illicit drugs most frequently used by human adolescents. Given the continued neurodevelopment throughout adolescence, adolescents may be more vulnerable than adults to certain neural consequences of heavy marijuana use. This study aimed to assess whether an experimental model of adolescent chronic exposure to Δ9‐tetrahydrocannabinol (THC), may induce lasting effects on learning and memory. Adolescent rats have been treated with THC or its vehicle from 35 to 45 postnatal days (PND) and left undisturbed until their adulthood (75 PND) when aversive and spatial memory was assessed using the passive avoidance and radial maze tasks. No alteration was found in aversive memory, but in the radial maze THC pretreated animals exhibited a worse performance than vehicles, suggesting a deficit in spatial working memory. To correlate memory impairment to altered neuroplasticity, level of marker proteins was investigated in the hippocampus, the most relevant area mediating spatial memory. A significant decrease in the astroglial marker glial fibrillar acid protein was found as well as in pre‐ and postsynaptic protein expression (VAMP2, PSD95) and NMDA receptor levels in pretreated rats. To parallel these changes to alteration in dendritic morphology, Golgi‐Cox staining was performed in the hippocampal dentate gyrus. Pretreated rats had a significantly lower total dendritic length and number than vehicles, as well as reduced spine density. Our data suggest that THC pretreated rats may establish less synaptic contacts and/or less efficient synaptic connections throughout the hippocampus and this could represent the molecular underpinning of the cognitive deficit induced by adolescent THC treatment. © 2009 Wiley‐Liss, Inc.
A molecular blueprint of gene expression in hippocampal subregions CA1, CA3, and DG is conserved in the brain of the common marmoset
Authors: Datson N.A. , Morsink M.C. , Steenbergen P.J. , Aubert Y. , Schlumbohm C. , Fuchs E. , de Kloet E.R.
Published: January 2009

Recent studies in rodents have shown that there are significant differences in gene expression profiles between the hippocampal subregions CA1, CA3, and DG. These differences in molecular make‐up within the hippocampus most likely underlie the differences in morphology, physiology, and vulnerability to insults that exist between the subregions of the hippocampus and are as such part of the basic molecular architecture of the hippocampus. The aim of this study was to investigate at large scale whether these subregional differences in gene expression are conserved in the hippocampus of a nonhuman primate, the common marmoset. This study is very timely, given the recent development of the first marmoset‐specific DNA microarray, exclusively containing sequences targeting transcripts derived from the marmoset hippocampus. Hippocampal subregions CA1, CA3, and DG were isolated by laser microdissection and RNA was isolated, amplifed, and hybridized to the marmoset‐specific microarray (EUMAMA) containing more than 1,500 transcripts expressed in the adult marmoset hippocampus. Large differences in expression were observed in particular between the DG region and both pyramidal subregions. Moreover, the subregion‐specific patterns of gene expression showed a remarkable conservation with the rodent brain both in terms of individual genes and degree of differential expression. To our knowledge, this is the first study investigating large scale hippocampal gene expression in a nonhuman primate. The obtained expression profiles not only provide novel data on the expression of more than 1,500 transcripts per hippocampal subregion but also are of potential interest to neuroscientists interested in the role of the different subregions in learning and memory in the nonhuman primate brain. © 2009 Wiley‐Liss, Inc.
Costing of clinical services in rural district hospitals in northern Vietnam
Authors: Minh Hoang Van , Giang Kim Bao , Huong Dao Lan , Huong Le Thi , Huong Nguyen Thuy , Giang Pham Ngan , Hoat Luu Ngoc , Wright Pamela
Published: January 2009

Objectives: This study aimed to estimate and analyse the “actual” unit cost of providing key clinical services in selected rural district hospitals in the North of Vietnam. It also examined the relationship between actual costs and the levels of cost covered by the corresponding user fees paid by patients.

Methods: This was a facility‐based costing study which estimates the costs of health care services from the perspective of the service providers. Three rural district hospitals from three provinces in the North of Vietnam were purposively selected for this study. The “step‐down” approach was applied.

Results: There was little difference in the costs of an outpatient visit across the hospitals, but the costs of an operation and an inpatient day varied considerably. In terms of cost structure, personnel costs accounted for the highest share of total cost of the clinical services. The shares of operating cost were considerable while depreciation of buildings/equipments made up a small “proportion”. The study results revealed that the user fee levels were much lower than the actual costs of providing the corresponding services. The present study highlights the importance of costing data for hospital planning and management. Copyright © 2009 John Wiley & Sons, Ltd.
A population‐based cohort study on the use of hormone treatment and endometrial cancer in southern Sweden
Authors: Epstein Elisabeth , Lindqvist Pelle G. , Olsson Håkan
Published: January 2009

Our aim was to determine the risk of endometrial cancer associated with long‐term use of combined hormone therapy (HT) and low‐potency estrogens. In this prospective population‐based cohort, 40,000 women aged 25–64 years, without prior cancer or hysterectomy, were included. The women answered 2 questionnaires at a 10‐year interval regarding HT use and personal details. Women were followed up for an average of 15.5 years through the National Cancer and Causes of Death Registry, representing 236,611 women years. Among the 17,822 postmenopausal women included, 166 cases of endometrial cancer were diagnosed. Only use of combined HT was related to a decreased risk of endometrial cancer (OR 0.3, 95% CI 0.1–0.8), the protective effect was found after 2 years, and increased with extended duration of use. “Only use” of low‐potency estrogens increased the risk of endometrial cancer almost to the same extent as use of high‐potency estrogens (OR 2.0, 95% CI 1.1–3.6vs. OR 2.5, 95% CI 1.3–4.8), the increased risk was confined to non‐obese women in both groups. The risk was significantly increased for oral but not for local low‐potency estrogen users (OR 2.1, 95% CI 1.1–3.6vs. OR 1.5, 95% CI 0.4–6.2, respectively). In long‐term estrogen users the risk was highest during the first 2 years, dropping slightly thereafter. Since low‐potency estrogen use increases the risk of endometrial cancer almost as much as high‐potency estrogen use, they should only be given if medically indicated. © 2009 UICC
Family history of colorectal cancer: A determinant of advanced adenoma stage or adenoma multiplicity?
Authors: Wark Petra A. , Wu Kana , van 't Veer Pieter , Fuchs Charles F. , Giovannucci Edward L.
Published: January 2009

A family history of colorectal cancer may increase colorectal cancer risk by influencing adenoma growth or enhancing the formation of new lesions. Data of men from the prospective Health Professionals Follow‐Up Study who underwent an endoscopy between 1986 and 2004 were used to evaluate whether a family history of colorectal cancer is associated with adenoma multiplicity or advanced adenoma stage (≥1 cm, histology with villous component or carcinoma in situ). 21.4% of the 3,881 adenoma patients and 13.9% of the 24,959 adenoma‐free men had a first‐degree relative with colorectal cancer. Thousand four hundred and ninety‐six men were classified as having advanced and 1,507 as having nonadvanced adenomas. Six hundred and twenty‐two men had multiple and 1,985 had single adenomas in the distal colon and rectum. A family history of colorectal cancer was similarly associated with advanced and nonadvanced adenomas [multivariable odds ratio (OR) (95% confidence interval): advanced vs. nonadvanced, 0.98 (0.82–1.17), advanced vs. adenoma‐free: 1.67 (1.47–1.91), nonadvanced vs. adenoma‐free: 1.70 (1.49–1.94)], although potential differences according to adenoma location were seen. A family history of colorectal cancer was more strongly associated with multiple distally located adenomas [odds ratio (95% confidence interval): multiple vs. single, 1.35 (1.09–1.68), multiple vs. no distally located adenomas: 2.02 (1.67–2.44), single vs. no distally located adenomas: 1.49 (1.32–1.68)]. The number of adenomas was also positively associated with a family history of colorectal cancer. Our findings suggest that at the population level, heritable factors may be more important in earlier stages of adenoma formation than at stages of adenoma advancement for at least distally located adenomas. © 2009 UICC
Recent patterns in gastric cancer: A global overview
Authors: Bertuccio Paola , Chatenoud Liliane , Levi Fabio , Praud Delphine , Ferlay Jacques , Negri Eva , Malvezzi Matteo , La Vecchia Carlo
Published: January 2009

Until the mid‐1990s, gastric cancer has been the first cause of cancer death worldwide, although rates had been declining for several decades and gastric cancer has become a relatively rare cancer in North America and in most Northern and Western Europe, but not in Eastern Europe, Russia and selected areas of Central and South America or East Asia. We analyzed gastric cancer mortality in Europe and other areas of the world from 1980 to 2005 using joinpoint regression analysis, and provided updated site‐specific incidence rates from 51 selected registries. Over the last decade, the annual percent change (APC) in mortality rate was around −3, −4% for the major European countries. The APC were similar for the Republic of Korea (APC = −4.3%), Australia (−3.7%), the USA (−3.6%), Japan (−3.5%), Ukraine (−3%) and the Russian Federation (−2.8%). In Latin America, the decline was less marked, but constant with APC around −1.6% in Chile and Brazil, −2.3% in Argentina and Mexico and −2.6% in Colombia. Cancers in the fundus and pylorus are more common in high incidence and mortality areas and have been declining more than cardia gastric cancer. Steady downward trends persist in gastric cancer mortality worldwide even in middle aged population, and hence further appreciable declines are likely in the near future. © 2009 UICC
Activated leukocyte cell adhesion molecule: A novel biomarker for breast cancer
Authors: Kulasingam Vathany , Zheng Yingye , Soosaipillai Antoninus , Leon Antonette E. , Gion Massimo , Diamandis Eleftherios P.
Published: January 2009

Activated leukocyte cell adhesion molecule (ALCAM) has been implicated in tumorigenesis. Our goal was to examine the levels of ALCAM, in addition to the classical breast cancer tumor markers carbohydrate antigen 15‐3 (CA15‐3) and carcinoembryonic antigen (CEA), in serum by quantitative enzyme‐linked immunosorbent assay for diagnosis in breast cancer patients. The 3 proteins were measured in serum of 100 healthy women, 50 healthy men and 150 breast carcinoma patients. The diagnostic sensitivity and specificity of the tests were calculated and the association of serum marker concentrations with various clinicopathologic variables was examined using nonparametric Kruskal‐Wallis tests. Receiver operating characteristic (ROC) curves were used to evaluate the diagnostic performance of the biomarkers. ALCAM, with area under the curve (AUC) of 0.78 [95% CI: 0.73, 0.84] outperformed CA15‐3 (AUC = 0.70 [95% CI: 0.64, 0.76]) and CEA (AUC= 0.63 [95% CI: 0.56, 0.70]). The incremental values of AUC for ALCAM over that for CA15‐3 were statistically significant (Delong test, p < 0.05). Combining CA15‐3 and ALCAM yielded a ROC curve with an AUC of 0.81 (95% CI [0.75, 0.87]). Serum ALCAM appears to be a new biomarker for breast cancer and may have value for disease diagnosis. © 2009 UICC
Retracted: Inhibition of non‐neuronal α7‐nicotinic receptor reduces tumorigenicity in A549 NSCLC xenografts
Authors: Paleari Laura , Sessa Fausto , Catassi Alessia , Servent Denis , Mourier Gilles , Doria‐Miglietta Guido , Ognio Emanuela , Cilli Michele , Dominioni Lorenzo , Paolucci Massimo , Calcaterra Andrea , Cesario Alfredo , Margaritora Stefano , Granone Pierluigi , Russo Patrizia
Published: January 2009

Retraction: The following article from International Journal of Cancer, "Inhibition of non‐neuronal α7‐nicotinic receptor reduces tumorigenicity in A549 NSCLC xenografts", by Laura Paleari, Fausto Sessa, Alessia Catassi, Denis Servent, Gilles Mourier, Guido Doria‐Miglietta, Emanuela Ognio, Michele Cilli, Lorenzo Dominioni, Massimo Paolucci, Andrea Calcaterra, Alfredo Cesario, Stefano Margaritora, Pierluigi Granone and Patrizia Russo, published online in Wiley InterScience (http://www3.interscience.wiley.com) on 22 January 2009, Volume 125, Issue 1, pages 199‐211, has been retracted by agreement between the authors, the journal Editor in Chief, Peter Lichter, and Wiley Periodicals, Inc. The retraction has been agreed due to unverified data.
Mitochondrial potassium channels
Authors: Szewczyk Adam , Jarmuszkiewicz Wieslawa , Kunz Wolfram S.
Published: January 2009

Mitochondrial potassium channels are believed to contribute to cytoprotection of injured cardiac and neuronal tissues. The following potassium channels have been described in the inner mitochondrial membrane: the ATP‐regulated potassium channel, the large conductance Ca2+‐activated potassium channel, the voltage‐gated Kv1.3 potassium channel, and the twin‐pore domain TASK‐3 potassium channel. The putative functional roles of these channels include changes in mitochondrial matrix volume, mitochondrial respiration, and membrane potential. In addition, the activity of these channels modulates the generation of reactive oxygen species by mitochondria. In this article, we discuss recent observations on three fundamental issues concerning mitochondrial potassium channels: (i) their molecular identity, (ii) their interaction with potassium channel openers and inhibitors, and (iii) their functional properties. © 2009 IUBMB IUBMB Life, 61(2): 134–143, 2009
Origin and evolution of the genetic code: The universal enigma
Authors: Koonin Eugene V. , Novozhilov Artem S.
Published: January 2009

The expansion of the standard code according to the coevolution theory. Phase 1 amino acids are orange, and phase 2 amino acids are green. The numbers show the order of amino acid appearance in the code according to (99). The arrows define 13 precursor‐product pairs of amino acids, their color defines the biosynthetic families of Glu (blue), Asp (dark‐green), Phe (magenta), Ser (red), and Val (light‐green). See Origin and Evolution of the Genetic Code: The Universal Enigma by Koonin and Novozhilov, pp. 99‐111.
Improving the affinity of fibroblasts for bacterial cellulose using carbohydrate‐binding modules fused to RGD
Authors: Andrade F. K. , Moreira S. M G. , Domingues L. , Gama F. M. P.
Published: January 2009

The attachment of cells to biomedical materials can be improved by using adhesion sequences, such as Arg‐Gly‐Asp (RGD), found in several extracellular matrix proteins. In this work, bifunctional recombinant proteins, with a Cellulose‐Binding Module (CBM), from the cellulosome of Clostridium thermocellum and cell binding sequences—RGD, GRGDY—were cloned and expressed in E.coli. These RGD‐containing cellulose binding proteins were purified and used to coat bacterial cellulose fibres. Its effect on the cell adhesion/biocompatibility properties was tested using a mouse embryo fibroblasts culture. Bacterial cellulose (BC) secreted by Gluconacetobacter xylinus (=Acetobacter xylinum) is a material with unique properties and promising biomedical applications. CBMs adsorbs specifically and tightly on cellulose. Thus, they are a useful tool to address the fused RGD sequence (or other bioactive peptides) to the cellulose surface, in a specific and simple way. Indeed, fibroblasts exhibit improved ability to interact with bacterial cellulose sheets coated with RGD‐CBM proteins, as compared with cellulose treated with the CBM, that is, without the adhesion peptide. The effect of the several fusion proteins produced was analyzed. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
In vitro elution of moxifloxacin from cancellous bone allografts
Authors: Kanellakopoulou Kyriaki , Sahinides Theophilos , Tsaganos Thomas , Galanakis Nearchos , Giamarellou Helen , Giamarellos‐Bourboulis Evangelos J.
Published: January 2009

The characteristics of cancellous bone allografts as carriers of moxifloxacin are described. Particles of cancellous bone were compressed into a wire‐mesh cylinder and impregnated into a solution of moxifloxacin for different time periods. Five replicas were impregnated for 1 h; another five for 24 h; and another five for 48 h. Impregnated allografts were then transferred into vials containing 5 ml of Mueller‐Hinton broth and incubated at 37°C. Broth was replaced daily. Concentrations of moxifloxacin in broth were determined after analysis by an high performance liquid chromatography system. Moxifloxacin was eluted at very high concentrations within the first days. Concentrations remained above 100 μg/ml until day 8 and above 40 μg/ml until day 20. It is concluded that cancellous bone allografts may allow the adequate in vitro elution of moxifloxacin. The latter results support their application in experimental models of osteomyelitis. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
Experiment, thermal simulation, and characterizations on transmission laser coating of hydroxyapatite on metal implant
Authors: Cheng Gary J. , Ye Chang
Published: January 2009

Coating of bioceramic material, Hydroxyapatite (HAp), on metal implant has attracted many attentions in biomedical industry recently because its combination of good mechanical property and biocompatibility. However, most of current HAp coatings lack coating/substrate interfacial strength, and/or biocompatibility. The cell‐tissue attachment is affected by the degraded biocompatibility due to decomposition of HAp during high temperature processing. In this article, an innovative method, transmission laser coating (TLC), is investigated to coat HAp on Ti substrate with low temperature processing. This process enhances the HAp/Metal interfacial property of current coatings, while maintaining good biocompatibility. Experiments are conducted using a continuous neodymium‐doped yttrium aluminium garnet (Nd‐YAG) laser. Multiphysics simulation is conducted to simulate the temperature distribution in coatings and substrates during TLC processing. X‐ray energy dispersion spectrum is used to measure the chemical composition of HAp coatings after TLC process. Pull‐out tests are conducted to measure the interfacial strength between the HAp coating and Ti substrate. Cell culture study is conducted to qualitatively evaluate the biocompatibility after TLC of HAp particles. These results show that TLC processing will open new ways of producing biocompatible bioceramic coatings with controlled thickness, and at low processing temperature. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
The effect of scaffold architecture on properties of direct 3D fiber deposition of porous Ti6Al4V for orthopedic implants
Authors: Li J. P. , de Wijn J. R. , van Blitterswijk C. A. , de Groot K.
Published: January 2009

3D porous Ti6Al4V scaffolds were directly fabricated by a rapid prototyping technology, 3D fiber deposition (3DF). In this study, scaffolds with different structures were fabricated by changing fiber spacing and fiber orientation. The influence of different architectures on mechanical properties and permeability of the scaffold were investigated. Mechanical analysis revealed that compressive strength and E‐modulus increase with decreasing the porosity. Permeability measurements showed that not only the total porosity but also the porous structure can influence the permeability. 3DF was found to provide good control and reproducibility of the desired degree of porosity and the 3D structure. Results of this study demonstrate that the 3DF of Ti6Al4V give us flexibility and versatility to fabricate and improve scaffolds to better mimic the architecture and properties of natural bone and meet the requirements of bone graft substitutes and orthopedic and dental implants. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
Bioactivation of collagen matrices through sustained VEGF release from PLGA microspheres
Authors: Borselli Cristina , Ungaro Francesca , Oliviero Olimpia , d'Angelo Ivana , Quaglia Fabiana , La Rotonda Maria I. , Netti Paolo A.
Published: January 2009

The success of any tissue engineering implant relies upon prompt vascularization of the cellular construct and, hence, on the ability of the scaffold to broadcast specific activation of host endothelium and guide vessel ingrowth. Vascular endothelial growth factor (VEGF) is a potent angiogenic stimulator, and if released in a controlled manner it may enhance and guide scaffold vascularization. Therefore, the aim of this work was to realize a scaffold with integrated depots able to release VEGF in a controlled rate and assess the ability of this scaffold to promote angiogenesis. VEGF‐loaded poly(lactide‐co‐glycolide) (PLGA) microspheres were produced and included in a collagen scaffold. The release of VEGF from microspheres was tailored to be sustained over several weeks and occurred at a rate of ∼0.6 ng/day per mg of microspheres. It was found that collagen scaffolds bioactivated with VEGF‐loaded microspheres strongly enhanced endothelial cell activation and vascular sprouting both in vitro and in vivo as compared with a collagen scaffold bioactivated with free VEGF. This report demonstrates that by finely tuning VEGF release rate within a polymeric scaffold, sprouting of angiogenic vessels can be guided within the scaffolds interstices as well as broadcasted from the host tissues. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
In vivo performance of selective electron beam‐melted Ti‐6Al‐4V structures
Authors: Ponader Sabine , von Wilmowsky Cornelius , Widenmayer Martin , Lutz Rainer , Heinl Peter , Körner Carolin , Singer Robert F. , Nkenke Emeka , Neukam Friedrich W. , Schlegel Karl A.
Published: January 2009

Highly porous titanium structures are widely used for maxillofacial and orthopedic surgery because of their excellent mechanical properties similar to those of human bone and their facilitation of bone ingrowth. In contrast to common methods, the generation of porous titaniumproducts by selective electron beam melting (SEBM), an additive manufacturing technology, overcomes difficulties concerning the extreme chemical affinity of liquid titanium to atmospheric gases which consequently leads to strongly reduced ductility of the metal. The purpose of this study was to assess the suitability of a smooth compact and a porous Ti‐6Al‐4V structure directly produced by the SEBM process as scaffolds for bone formation. SEBM‐processed titanium implants were placed into defects in the frontal skull of 15 domestic pigs. To evaluate the direct contact between bone and implant surfaces and to assess the ingrowth of osseous tissue into the porous structure, microradiographs and histomorphometric analyses were performed 14, 30, and 60 days after surgery. Bone ingrowth increased significantly during the period of this study. After 14 days the most outer regions of the implants were already filled with newly formed bone tissue (around 14%). After 30 days the bone volume inside the implants reached almost 30% and after 60 days abundant bone formation inside the implants attained 46%. During the study only scarce bone–implant contact was found around all implants, which did not exceed 9% around compact specimens and 6% around porous specimens after 60 days. This work demonstrates that highly porous titanium implants with excellent interconnectivity manufactured using the SEBM method are suitable scaffolds for bone ingrowth. This technique is a good candidate for orthopedic and maxillofacial applications. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
Fibrin‐based tissue engineering scaffolds enhance neural fiber sprouting and delay the accumulation of reactive astrocytes at the lesion in a subacute model of spinal cord injury
Authors: Johnson Philip J. , Parker Stanley R. , Sakiyama‐Elbert Shelly E.
Published: January 2009

The purpose of this study was to evaluate the effects of fibrin scaffolds on subacute rat spinal cord injury (SCI). Long–Evans rats were anesthetized and underwent a dorsal hemisection injury; two weeks later, the injury site was re‐exposed, scar tissue was removed, and a fibrin scaffold was implanted into the wound site. An effective method for fibrin scaffold implantation following subacute SCI was investigated based on the presence of fibrin within the lesion site and morphological analysis 1 week after implantation. Prepolymerized fibrin scaffolds were found to be present within the lesion site 1 week after treatment and were used for the remainder of the study. Fibrin scaffolds were then implanted for 2 and 4 weeks, after which spinal cords were harvested and evaluated using markers for neurons, astrocytes, and chondroitin sulfate proteoglycans. Compared with untreated control, the fibrin‐treated group had significantly higher levels of neural fiber staining in the lesion site at 2 and 4 weeks after treatment, and the accumulation of glial fibrillary acidic protein (GFAP) positive reactive astrocytes surrounding the lesion was delayed. These results show that fibrin is conducive to regeneration and cellular migration and illustrate the advantage of using fibrin as a scaffold for drug delivery and cell‐based therapies for SCI. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
Enzymatically crosslinked porous composite matrices for bone tissue regeneration
Authors: Ciardelli Gianluca , Gentile Piergiorgio , Chiono Valeria , Mattioli‐Belmonte Monica , Vozzi Giovanni , Barbani Niccoletta , Giusti Paolo
Published: January 2009

Three‐dimensional porous hydroxyapatite/collagen (HA/Coll) composites with a random pore structure were obtained by freeze‐drying and crosslinked by an enzymatic treatment using microbial transglutaminase (mTGase). The procedure resulted in improved mechanical strength and thermal stability of the scaffolds. The scaffolds were characterized in terms of their stability (Coll release, swelling, collagenase‐mediated degradation), thermal properties (thermogravimetric analysis, differential scanning calorimetry), mechanical behavior under compression and cell compatibility. Enzymatic treatment stabilized the sponges to water vapors, with measurable swelling ratio between 100% for HA/Coll/mTGase 0/100 to 5% for HA/Coll/mTGase 80/20. Weight loss in water due to Coll release was between 2 and 10% in mTGase‐crosslinked samples and decreased with increasing HA content. Cultures of MG63 osteoblast‐like cells and human umbilical vein endothelial cells (HUVEC) showed good adhesion and proliferation on the scaffolds, good viability (through MTT test, 100–150% of control), and good differentiation (alkaline phosphatase, up to 40 UI/L with respect to 35 UI/L for control). © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
In vivo response of novel calcium phosphate‐mullite composites: Results up to 12 weeks of implantation
Authors: Nath Shekhar , Basu Bikramjit , Mohanty Mira , Mohanan P. V.
Published: January 2009

In this paper, the in vivo response, in particular, the histocompatibility of newly developed CaP‐mullite composites is reported. In the present experiments, the bioceramic implants were inserted in the long bones of healthy rabbits according to standard protocols (ISO‐10993) and the tissue response was studied at different time intervals of up to 12 weeks. Ultra high‐molecular weight polyethylene (UHMWPE) was used as control samples. The postimplant bone‐material interfaces were analyzed by staining of histological sections, following bone tissue histopathology protocols. The interface zones were critically observed by fluorescent optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). Importantly, no inflammation, necrosis was observed during this tenure. New bone formation was observed at all the implantation time intervals (1–12 weeks). However, the bone integrity with the material was increased after 12 weeks of implantation. Although macrophages and fibrous tissue were present during the first week of implantation, they were not observed on histology sections after 12 weeks postimplantation. More importantly, foci of chondrocytes could be observed after 12 weeks of implantation. Remodeling of Haversian canal was observed at the interfacial area of natural bone and implant material. All the observations were assessed critically to analyze the in vivo biocompatibility of this novel composite material. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Pivoting system fracture in a bileaflet mechanical valve: A case report
Authors: Zhang Hongbo , Deng Xiaoyan , Cianciulli Tomás Francisco , Zhang Ze , Chappard Daniel , Lax Jorge Alberto , Saccheri Maria Cristina , Redruello Hector Jorge , Jordana Jorge Luis , Prezioso Horacio Alberto , King Martin , Guidoin Robert
Published: January 2009

A leaflet escape occurred in a low profile bileaflet mechanical prosthesis manufactured by TRI‐Technologies that had been implanted for 3 years in the mitral position of a 32 year old patient. The escaped leaflet had embolized and was subsequently located by an abdominal computerized axial tomography scan and ultrasound in the terminal portion of the aortic bifurcation. The embolized leaflet was removed 3 months after valve replacement surgery. In an attempt to determine the cause of the escape the retrieved embolized leaflet was investigated. Techniques employed included visual examination aided by stereo‐microscopy, x‐ray imaging and scanning electron microscopy. One of the ears had fractured and was missing from the leaflet. Chipping was observed at the leaflet ear position on both the inflow and outflow surfaces. Visual and SEM observations found fractographic river‐lines that indicated an apparent origin at the inflow surface of the ear nearest to the straight ‘B‐datum’ line or coaptation edge. The origin seemed to be in the radius between the leaflet ear and the leaflet body. SEM observation of the remaining intact ear showed wear marks on both the inflow and outflow sides of the leaflet ear that corresponded to the suspected origin of fracture. It is believed that the use of boron alloyed pyrolytic carbon material and the leaflet's homogeneous monolithic structural design were factors that contributed to this adverse event. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Postimplantation pressure testing and characterization of laser bonded glass/polyimide microjoints
Authors: Mian Ahsan , Sultana Taslema , Georgiev Daniel , Witte Reiner , Herfurth Hans , Auner Greg , Newaz Golam
Published: January 2009

The stability of the laser bonded titanium coated glass/polyimide microjoints were studied in vivo by implanting on a rat brain surface for 10 days. In the current state, the strength of the joints were measured by a specially designed instrument called “pressure test” equipment where the samples were subjected to a variable pressure load (using high pressure nitrogen) controlled by a pressure regulator. The strength of the joints seems to degrade by about 28% as a result of soaking in rat brain. The bond degradation in rat brain implants is similar compared with those soaked in artificial cerebrospinal fluid (CSF) solution. Polyimide uptakes water through existing pores in it and also water gets in the joint region through the edges of the samples. Water might have caused oxidation of the chemical bonds which are thought to have formed by the laser fabrication process. A separate set of samples were created using same parameters for testing the hermeticity of the laser bonds. The samples were also exposed to rat brain CSF and were tested for hermiticity at the end of 10 days exposure time. It was observed that the implanted samples retained their hermeticity although the bond strength degraded by about 28%. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Coumestrol promotes proliferation and osteoblastic differentiation in rat bone marrow stromal cells
Authors: Wu Xiao‐tao , Wang Bin , Wei Ji‐nan
Published: January 2009

Although the effects of coumestrol on osteoblasts and osteoclasts can be summarized as increasing the bone density and preventing bone resorption, direct and detailed effects of coumestrol on bone marrow stromal cells remain obscure. In the present study, the effects of coumestrol on proliferation and osteoblastic differentiation of rat bone marrow stromal cells (BMSCs) have been investigated; the regulative effect of coumestrol on BMSCs and skeletal system has also been discussed. The results showed that treatment with coumestrol increased cellular activities (analyzed by MTT assay), alkaline phosphatase (ALP), type I collagen and osteocalcin (OCN) activity as well as the protein and gene expression of OPG, gene expression ratio of OPG/RANKL and gene expression of estrogen receptor α(ERα). These results demonstrate that phytoestrogen coumestrol has a direct enhancing effect on the proliferation and osteogenic differentiation of bone marrow stromal cells, which would lead to stimulation of bone formation, and it can also protect the whole skeletal system by regulating OPG/RANKL expression, and these effects may be mediated by ERα. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
The influence of chromatic components on extended depth of field imaging
Authors: Navas Javier , Martín Joaquín
Published: January 2009

The analysis of variance is one of the most commonly used algorithms for detecting focalized zones in digital images and is an entry point to extended focalization techniques beyond those established by optical laws. This article analyses the dependence of the red, green, and blue (RGB) and lightness, hue, and saturation (LHS) components when used as the basis for applying an algorithm to obtain images with extended depth of field. Also, an algorithm developed by the authors is described and the dependence of the final result is shown according to the chromatic components used as the variables. Finally, a methodology is defined based on the study of second variance in relation to the number of images and pixels of the chromatic coordinates to decide which to use as the basis for the calculation. Microsc. Res. Tech., 2009. © 2009 Wiley‐Liss, Inc.
Detection of pollen grains in multifocal optical microscopy images of air samples
Authors: Landsmeer Sander H. , Hendriks Emile A. , de Weger Letty A. , Reiber Johan H.C. , Stoel Berend C.
Published: January 2009

Pollen is a major cause of allergy and monitoring pollen in the air is relevant for diagnostic purposes, development of pollen forecasts, and for biomedical and biological researches. Since counting airborne pollen is a time‐consuming task and requires specialized personnel, an automated pollen counting system is desirable. In this article, we present a method for detecting pollen in multifocal optical microscopy images of air samples collected by a Burkard pollen sampler, as a first step in an automated pollen counting procedure. Both color and shape information was used to discriminate pollen grains from other airborne material in the images, such as fungal spores and dirt. A training set of 44 images from successive focal planes (stacks) was used to train the system in recognizing pollen color and for optimization. The performance of the system has been evaluated using a separate set of 17 image stacks containing 65 pollen grains, of which 86% was detected. The obtained precision of 61% can still be increased in the next step of classifying the different pollen in such a counting system. These results show that the detection of pollen is feasible in images from a pollen sampler collecting ambient air. This first step in automated pollen detection may form a reliable basis for an automated pollen counting system. Microsc. Res. Tech., 2009. © 2009 Wiley‐Liss, Inc.
Mapping of T1‐values and Gadolinium‐concentrations in MRI as indicator of disease activity in luminal Crohn's disease: A feasibility study
Authors: Horsthuis Karin , Nederveen Aart J. , de Feiter Marijn‐Willem , Lavini Cristina , Stokkers Pieter C.F. , Stoker Jaap
Published: January 2009

Purpose

To determine the feasibility of T1‐mapping and calculation of Gadolinium‐values in luminal Crohn's Disease (CD).

Materials and Methods

Nine patients with active CD were included. For each patient disease activity was determined, based on endoscopic and histopathological results. The Crohn's Disease Endoscopic Index of Severity (CDEIS), the Harvey‐Bradshaw index (HBI) and C‐reactive protein (CRP) were also determined as reference standards. T1‐measurements were performed before and after intravenous administration of Gadodiamide in 14 slices in a single breath‐hold using the Look‐Locker (LL) sequence in combination with a segmented three‐dimensional Turbo Field Echo sequence. A Region of Interest (ROI) was drawn around inflamed bowel loops and the mean Gadolinium‐concentration within the ROI was calculated. Gadolinium‐concentrations were compared between patients with mild and marked disease, as determined by the reference standards.

Results

Mean Gadolinium‐concentrations were higher in bowel loops of patients with more active disease, as defined by endoscopic and histopathological examination, CRP, and HBI.

Conclusion

By using a breath‐hold LL sequence in the bowel quantitative assessment of contrast agent concentration is possible, thus permitting objective evaluation of physiological changes in actively inflamed tissue in an area that suffers from motion problems. J. Magn. Reson. Imaging 2009;29:488–493. © 2009 Wiley‐Liss, Inc.
MR study of the effect of infarct size and location on left ventricular functional and microstructural alterations in porcine models
Authors: Wu Yin , Chan Carmen W. , Nicholls John M. , Liao Songyan , Tse Hung‐Fat , Wu Ed X.
Published: January 2009

Purpose

To investigate the effect of infarct size and location on left ventricular (LV) functional and microstructural alterations in well‐established porcine models.

Materials and Methods

Myocardium infarction was induced in mini‐pigs at apical septum (Group 1, n = 6) or basal lateral wall (Group 2, n = 6) by permanent occlusion of the left anterior descending or left circumflex coronary artery, respectively. In vivo cardiac magnetic resonance (CMR) was performed 4 and 13 weeks later. Hearts were then excised and examined by ex vivo diffusion tensor imaging (DTI) for myocardium structural changes in infarct, adjacent and remote regions.

Results

LV ejection fractions correlated negatively with infarct sizes. Between week 4 and 13, Group 1 exhibited more changes in end‐systolic volume, LV mass, and ejection fraction, although it showed a smaller infarct volume percentage. Ex vivo results revealed the decreased water diffusion fractional anisotropy and increased diffusivities in infarct region in correlation with infarct size, but with no significant difference between the two groups. However, LV myocardial double‐helical fiber architecture was found to alter in Group 1, shifting more towards left‐handed direction as compared to controls.

Conclusion

Postinfarct LV functional and structural remodeling is affected by both infarct size and location. J. Magn. Reson. Imaging 2009;29:305–312. © 2009 Wiley‐Liss, Inc.