bluuebunny/crossref_metadata_2025 huggingface dataset:
Does the whole equal the sum of the parts? Patient‐assigned utility scores for IBS‐related health states and profiles
Authors: Brazier John , Dolan Paul , Karampela Korina , Towers Isabel
Published: January 2006

The quality‐adjusted life year (QALY) assumes that the value of a health state is linearly related to the time spent in it, which implies that the value of a health state is independent of the states which precede or follow it. Irritable bowel syndrome (IBS) is a suitable condition to test this assumption since it is subject to considerable fluctuations over time.

Forty‐nine IBS patients were asked to rate their own health using generic measures of health and a condition specific classification. They were then asked to value five IBS states and four profiles using a self‐completed version of the standard gamble technique. The implied value of each profile was estimated using the QALY assumption of linearity over time and compared with the direct profile valuations.

The directly elicited profile values suggest that reductions in the duration of IBS symptoms has less of an impact on the value of quality of life than would be implied by the QALY assumption of linearity over time, though the differences were small. There are a number of competing explanations for this finding, including possible sequence effects, quantity effects or time preference, or it might be due to gestalt effects resulting in a neglect of time spent in symptomatic states of health. Copyright © 2005 John Wiley & Sons, Ltd.
Does non‐profit health insurance reduce financial burden? Evidence from the Vietnam living standards survey panel
Authors: Sepehri Ardeshir , Sarma Sisira , Simpson Wayne
Published: January 2006

Many low‐income countries are implementing non‐profit medical insurance to increase access to health services, especially among low‐income households, and to raise additional revenue for financing public health services. This paper estimates the effect of insurance on out‐of‐pocket health expenditures using the Vietnam Living Standards Surveys for 1993 and 1998 and appropriate models for panel data. Our findings suggest that health insurance reduces health expenditure when unobserved heterogeneity is accounted for. Failure to capture unobserved heterogeneity produces contrary results that are consistent with previous cross‐sectional studies in the literature. Health insurance is found to reduce out‐of‐pocket expenditure between 16 and 18% and the reduction in expenditure is more pronounced for individuals with lower incomes. At mean income, the effect of health insurance is to reduce health expenditures between 28 and 35%. Copyright © 2005 John Wiley & Sons, Ltd.
A preference‐based index for the SF‐12
Authors: Stratmann‐Schoene D. , Kuehn T. , Kreienberg R. , Leidl R.
Published: January 2006

Background: The SF‐12 is a widely used generic measure of subjective health. As the scoring algorithms of the SF‐12 do not include preference values, different approaches to assign a preference‐based index are available that should be tested regarding their feasibility and validity.

Objectives: To develop a concept for a preference‐based index for the SF‐12 on the basis of multi‐attribute decision analysis and to perform initial tests of its feasibility and validity in an empirical study.

Methods: A multi‐attribute preference function for the SF‐12 was developed, estimated and tested for validity. Two mail surveys (n = 100, 200) and an interview (n = 72) were conducted with women who had an operation for breast cancer. Visual analogue scale (VAS) and standard gamble (SG) measures elicited preference‐based valuations.

Results: Eight attributes were identified in the SF‐12. Validity tests showed an average difference of 8 VAS score points between directly measured and predicted values for given health states.

Conclusion: The initial results show that this approach might allow the direct assignment of a preference‐based valuation to the SF‐12. The quality of the psychometric features of the multi‐attribute value function is encouraging. Future studies should test this concept more extensively, especially by determining parameters for a representative sample of the general population and by comparing performance with other approaches to value the SF‐12. Copyright © 2005 John Wiley & Sons, Ltd.
Evaluation of the cognitive, psychomotor and pharmacokinetic profiles of rupatadine, hydroxyzine and cetirizine, in combination with alcohol, in healthy volunteers
Authors: Barbanoj Manuel J. , García‐Gea Consuelo , Antonijoan Rosa , Izquierdo Iñaki , Donado Ester , Pérez Iñaki , Solans Anna , Jané Francesc
Published: January 2006

Introduction

The Central Nervous System (CNS) impairment induced by moderate alcohol (ALC) ingestion may be enhanced if other drugs are taken simultaneously. Rupatadine (RUP) is a new H1‐antihistamine which also inhibits platelet activating factor (PAF) release in inflammatory reactions.

Objective

The main aim of the study was to assess the effects of ALC 0.8 g/Kg on RUP (10 mg and 20 mg) CNS effects. An evaluation of alcohol and RUP pharmacokinetics was also attained.

Methods

Eighteen healthy young volunteers of both sexes participated in a phase I, randomised, crossover, double‐blind, placebo‐controlled study. At 2‐week intervals they received six treatments: (a) placebo (PLA), (b) ALC alone and ALC in combination with: (c) hydroxyzine 25 mg (HYD), (d) cetirizine 10 mg (CET), (e) RUP 10 mg or (f) RUP 20 mg. At baseline and several times thereafter, seven psychomotor performance tests (finger tapping, fine motoric skills, nystagmus, temporal estimation, critical‐flicker‐fusion frequency, ‘d2’ cancellation, simple reaction) and eleven subjective self‐reports (drunkenness, sleepiness, alertness, clumsiness, anger, inattentiveness, efficiency, happiness, hostility, interest and extraversion) were carried out. Two‐way (treatment, time) ANOVAs for repeated measures to each variable together with a multivariate non‐parametric approach were applied. Plasma concentrations of alcohol, and of RUP and its metabolites, were quantified by validated immunofluorescence and LC/MS/MS methods, respectively. Plasma‐time curves for all compounds were analysed by means of model‐independent methods.

Results

The combination of alcohol with HYD, CET and RUP 20 mg produced more cognitive and psychomotor impairment as compared to alcohol alone, being the combination of alcohol and HYD the one which induced the greatest deterioration. The combination of alcohol and RUP 10 mg could not be differentiated from ALC alone. Subjective self‐reports reflect effects on metacognition after the combination of alcohol with HYD and CET i.e. the increased objective impairment observed was not subjectively perceived by the subjects. No significant differences were obtained when comparing alcohol plasma concentrations assessed after the treatments evaluated. RUP showed a lineal kinetic relationship after 10 and 20 mg with a higher exposition to both metabolites assayed.

Conclusions

Present results showed that single oral doses of rupatadine 10 mg in combination with alcohol do not produce more cognitive and psychomotor impairment than alcohol alone. Higher doses of rupatadine, in combination with alcohol, may induce cognitive and psychomotor deterioration as hydroxyzine and cetirizine at therapeutic doses. Copyright © 2006 John Wiley & Sons, Ltd.
Acute effect of isometric exercise on desire to smoke and tobacco withdrawal symptoms
Authors: Ussher Michael , West Robert , Doshi Reena , Sampuran Amandeep Kaur
Published: January 2006

A brief bout of aerobic exercise (e.g. stationary bicycle) has been shown to result in an acute reduction in tobacco withdrawal symptoms and cravings in abstinent smokers. However, aerobic exercise is often not practical and it is of interest to examine whether non‐aerobic exercise has a similar effect. We investigated whether isometric exercise (involving muscular contractions against resistance without movement, e.g. placing the palms of the hands together and pushing) reduces desire to smoke and tobacco withdrawal symptoms. Following overnight abstinence smokers were randomized to 5‐min of: isometric exercises (n = 20), body scanning (focusing attention on sensations in different areas of the body, n = 20, control), or sitting passively (n = 20, control). Desire to smoke and tobacco withdrawal symptoms (‘irritable’, ‘depressed’, ‘stressed’, ‘tense’, ‘restless’ and ‘poor concentration’) were rated at baseline, immediately post‐intervention, and 5‐, 10‐, 15‐ and 20‐min post‐intervention. Isometric exercise produced a significantly greater reduction in desire to smoke versus passive control at immediate post‐intervention and 5‐min post‐intervention, relative to baseline (p < 0.05). Most withdrawal symptoms were significantly moderated by exercise versus controls at some point between 5‐ to 20‐min post‐intervention, relative to baseline (p < 0.05). Brief isometric exercise has potential for offering immediate relief from a desire to smoke. Copyright © 2006 John Wiley & Sons, Ltd.
Pharmacological management of behavioural and psychological disturbance in dementia
Authors: Kozman Mervat N. , Wattis John , Curran Stephen
Published: January 2006

Behavioural and psychological symptoms in patients with dementia are common, distressing and often difficult to manage. This review evaluates a range of drugs commonly used to manage these symptoms including antipsychotics, anticonvulsants, antidementia drugs and antidepressants.

The risks and benefits of individual treatments are discussed and the relatively poor evidence base and need for further research is highlighted. Copyright © 2006 John Wiley & Sons, Ltd.
Controlled drug release from a novel injectable biodegradable microsphere/scaffold composite based on poly(propylene fumarate)
Authors: Kempen Diederik H. R. , Lu Lichun , Kim Choll , Zhu Xun , Dhert Wouter J. A. , Currier Bradford L. , Yaszemski Michael J.
Published: January 2006

The ideal biomaterial for the repair of bone defects is expected to have good mechanical properties, be fabricated easily into a desired shape, support cell attachment, allow controlled release of bioactive factors to induce bone formation, and biodegrade into nontoxic products to permit natural bone formation and remodeling. The synthetic polymer poly(propylene fumarate) (PPF) holds great promise as such a biomaterial. In previous work we developed poly(DL‐lactic‐co‐glycolic acid) (PLGA) and PPF microspheres for the controlled delivery of bioactive molecules. This study presents an approach to incorporate these microspheres into an injectable, porous PPF scaffold. Model drug Texas red dextran (TRD) was encapsulated into biodegradable PLGA and PPF microspheres at 2 μg/mg microsphere. Five porous composite formulations were fabricated via a gas foaming technique by combining the injectable PPF paste with the PLGA or PPF microspheres at 100 or 250 mg microsphere per composite formulation, or a control aqueous TRD solution (200 μg per composite). All scaffolds had an interconnected pore network with an average porosity of 64.8 ± 3.6%. The presence of microspheres in the composite scaffolds was confirmed by scanning electron microscopy and confocal microscopy. The composite scaffolds exhibited a sustained release of the model drug for at least 28 days and had minimal burst release during the initial phase of release, as compared to drug release from microspheres alone. The compressive moduli of the scaffolds were between 2.4 and 26.2 MPa after fabrication, and between 14.9 and 62.8 MPa after 28 days in PBS. The scaffolds containing PPF microspheres exhibited a significantly higher initial compressive modulus than those containing PLGA microspheres. Increasing the amount of microspheres in the composites was found to significantly decrease the initial compressive modulus. The novel injectable PPF‐based microsphere/scaffold composites developed in this study are promising to serve as vehicles for controlled drug delivery for bone tissue engineering. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Corrosion resistance of a laser spot‐welded joint of NiTi wire in simulated human body fluids
Authors: Yan Xiao‐Jun , Yang Da‐Zhi
Published: January 2006

The purpose of this study was to investigate corrosion resistance of a laser spot‐welded joint of NiTi alloy wires using potentiodynamic tests in Hank's solution at different PH values and the PH 7.4 NaCl solution for different Cl− concentrations. Scanning electron microscope observations were carried out before and after potentiodynamic tests. The composition of a laser spot‐welded joint and base metal were characterized by using an electron probe microanalyzer. The results of potentiodynamic tests showed that corrosion resistance of a laser spot‐welded joint of NiTi alloy wire was better than that of base metal, which exhibited a little higher breakdown potential and passive range, and a little lower passive current density. Corrosion resistances of a laser spot‐welded joint and base metal decreased with increasing of the Cl− concentration and PH value. The improvement of corrosion resistance of the laser spot‐welded joint was due to the decrease of the surface defects and the increase of the Ti/Ni ratio. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Improvement of cell adhesion on poly(L‐lactide) by atmospheric plasma treatment
Authors: Nakagawa Masafumi , Teraoka Fumio , Fujimoto Shinji , Hamada Yoshinosuke , Kibayashi Hiroyuki , Takahashi Junzo
Published: January 2006

The purpose of this study is to elucidate the interaction between the cell and the surface of poly(L‐lactide) (PLLA) samples, which were modified using a low‐temperature plasma treatment apparatus at atmospheric pressure. The plasma treatments were carried out in the atmospheres of air, carbon dioxide (CO2), and perfluoro propane (C3F8) gas. The PLLA samples before and after the plasma treatment were analyzed by XPS and their contact angles with water. Furthermore, the cell adhesion capability and cell mass culturing tests on the PLLA samples were carried out using MC3T3‐E1 cells. The results showed that the contact angle of the samples, which was plasma treated in air or in CO2 gas, decreased compared with that of the untreated samples. On the other hand, the contact angle of the samples, which was plasma treated in the C3F8 gas, increased compared with the untreated plasma samples. The cell response on the PLLA samples plasma treated in air or in the CO2 gas were significantly superior to that of the PLLA samples, which was plasma treated in the C3F8 gas. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Lymphangiogenesis in the bone–implant interface of orthopedic implants: Importance and consequence
Authors: Jell Gavin , Kerjaschki Dontscho , Revell Peter , Al‐Saffar Najat
Published: January 2006

The lymphatic system plays an essential physiological role in homeostasis, interstitial fluid composition, and immunity while impaired lymphatic function has been implicated in a number of pathological conditions, including arthritis and delayed wound healing. This study investigated lymphatic capillary growth and lymphangiogenesis pathways in the bone–implant interface from patients with aseptically loosened prosthetic joints. The newly developed lymphatic specific marker, podoplanin, has enabled the first demonstration of lymphatic capillaries in peri‐prosthetic tissues (60% of cases contained podoplanin positive vessels). The pro‐lymphangiogenic factor (VEGF‐C) and its receptor VEGFR‐3 showed high level of expression in these tissues, (often in areas of high levels of wear debris). However despite the upregulation of the lymphangiogenesis pathway by a VEGF‐C/VEGFR‐3‐mediated mechanism, there were relatively few podoplanin positive lymphatic vessels in the bone–implant interface (3.4% of total vessels). This may have important pathological consequences in terms of perpetuating inflammation and edema by inhibiting the removal of macromolecules, cells, and interstitial fluid. The identification of lymphatic vessels with internalized polyethylene wear particles provides evidence of this route of wear debris transportation to distal sites. This paper highlights the importance of lymphatic vessels in the maintenance of local and distal inflammatory responses to prosthetic wear particles. © 2005 Wiley Periodicals, Inc. J. Biomed. Mater. Res, 2006.
Encapsulating drugs in biodegradable ultrafine fibers through co‐axial electrospinning
Authors: Huang Zheng‐Ming , He Chuang‐Long , Yang Aizhao , Zhang Yanzhong , Han Xiao‐Jian , Yin Junlin , Wu Qingsheng
Published: January 2006

This article describes an electrospinning process to fabricate double‐layered ultrafine fibers. A bioabsorbable polymer, Polycaprolactone (PCL), was used as the outer layer or the shell and two medically pure drugs, Resveratrol (RT, a kind of antioxidant) and Gentamycin Sulfate (GS, an antibiotic), were used as the inner layers or the cores. Morphology and microstructure of the ultrafine fibers were characterized by scanning electron microscope (SEM) and transmission electron microscopy (TEM), whereas mechanical performance of them was understood through tensile test. In vitro degradation rates of the nanofibrous membranes were determined by measuring their weight loss when immersed in pH 7.4 phosphate‐buffered saline (PBS) mixed with certain amount of Pseudomonas lipase for a maximum of 7 days. The drug release behaviors of the RT and GS were measured using a high performance liquid chromatography (HPLC) and ultraviolet–visible (UV–vis) spectroscopy, respectively. It has been found that the drug solutions without any fiber‐forming additive could be encapsulated in the PCL ultrafine fibers, although they alone cannot be made into a fiber form. Beads on the fiber surface influenced the tensile behavior of the ultrafine fibers remarkably. When the core solvent was miscible with the shell solvent, higher drug concentration decreased the bead formation and thus favored the mechanical performance. The situation, however, became different if the two solvents were immiscible with each other. The degradation rate was closely related to hydrophilicity of the drugs in the cores. Higher hydrophilicity apparently led to faster degradation. The release profiles of the RT and GS exhibited a sustained release characteristic, with no burst release phenomenon. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Cyto‐ and histocompatibility of multilayered DNA‐coatings on titanium
Authors: van den Beucken J.J.J.P. , Walboomers X.F. , Vos M.R.J. , Sommerdijk N.A.J.M. , Nolte R.J.M. , Jansen J.A.
Published: January 2006

DNA‐containing biomaterial coatings offer potential beneficial effects for both soft and hard tissue implants because of the structural properties of DNA. In the current study, the aim was to assess the in vitro cyto‐ and in vivo histocompatibility of multilayered DNA‐coatings generated using the electrostatic self‐assembly technique, with poly‐D‐lysine or poly(allylamine hydrochloride) as the cationic counterparts of anionic DNA. Multilayered DNA‐coatings were fabricated on titanium substrates. Noncoated titanium substrates served as controls. In vitro experiments with rat primary dermal fibroblasts (RDF) assessing their viability were performed using a Live/Dead assay and an MTT‐based assay. The presence of multilayered DNA‐coatings did not affect RDF cell viability. On the other hand, an increased proliferation was demonstrated on both types of multilayered DNA‐coatings. An in vivo rat model was used to study the soft tissue histocompatibility of subcutaneously inserted implants during implantation periods of 4 and 12 weeks. Light microscopic analysis revealed that all implants were surrounded by a fibrous capsule containing α‐smooth muscle actin, and that the presence of a multilayered DNA‐coating did not induce any adverse effects in terms of inflammation and wound healing. Histomorphometrically, no significant differences in capsule quality or thickness were observed dependent on multilayered DNA‐coating or implantation period. The cyto‐ and histocompatibility of multilayered DNA‐coatings demonstrated in this study allows their use and functionalization with appropriate compounds to modulate cell and tissue responses in dental and medical implantology. © 2005 Wiley Periodicals, Inc. J. Biomed. Mater. Res, 2006.
Susceptibility of nitinol to localized corrosion
Authors: Pound Bruce G.
Published: January 2006

The effect of different conditions on the susceptibility of nitinol to localized corrosion was examined using the cyclic potentiodynamic polarization technique. Tests were performed on mechanically polished (MP) and electropolished (EP) nitinol wire in 0.9 wt % NaCl and phosphate‐buffered saline (PBS). A polarization curve was also obtained for an EP stent in the NaCl. Differences between the breakdown potential and the corrosion potential (Ecorr) and between the protection potential and Ecorr were used to evaluate the susceptibility to pitting corrosion and crevice corrosion, respectively. The type of solution and, particularly, the surface condition affected the resistance of nitinol to pitting corrosion. Both EP and MP nitinol were more susceptible to breakdown in the NaCl than in PBS, indicating that the NaCl provides a more severe test environment than does PBS. Electropolishing increased the breakdown resistance of nitinol in PBS and the NaCl, as found in previous studies with Hank's solution. Surface condition, however, did not have a significant effect on the repassivation behavior of nitinol, as is also the case with titanium. The EP wire and stent showed similar breakdown and repassivation behavior in the NaCl, suggesting that the nature of the EP surface was similar in both cases. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Concentration‐dependent effects of titanium and aluminium ions released from thermally oxidized Ti6Al4V alloy on human osteoblasts
Authors: Saldaña L. , Barranco V. , García‐Alonso M.C. , Vallés G. , Escudero M.L. , Munuera L. , Vilaboa N.
Published: January 2006

Thermal oxidation treatments of Ti6Al4V, at 500 and 700°C, for 1 h result in the formation of an outer “ceramic” layer of rutile, which enhances osteoblast response. In the present study, we have measured in vitro Ti and Al ion release from Ti64 alloy in the as‐received state and after thermal oxidation treatments at 500 or 700°C, to culture medium under standard cell‐culture conditions. Concentrations of both Ti and Al released from both thermal oxidation treatments were lower than from polished alloy. Al was released from the treated or untreated surfaces in substantially lower extent than Ti. Titanium and aluminium ions affected primary human osteoblast proliferation, metabolic activity, and differentiation in a dose‐dependent manner. Treatments with individual Ti or Al metal ions in similar concentration ranges than released from the surfaces did not alter osteoblast response, which also remained unaffected after treatments with combinations of Ti plus Al applied in the proportional relations than detected in ion‐release experiments. We then selected higher concentrations of Ti that impaired osteoblast proliferation and differentiation, while the proportional lower concentrations of Al did not alter osteoblast behavior. In spite of its inert character, it was found that Al significantly enhanced the deleterious effect of Ti on osteoblast differentiation. Therefore, thermal oxidation treatments of Ti6Al4V alloy may improve the biocompatibility of the alloy by reducing both Ti and Al release, and thus attenuating ion‐mediated interference with osteoblast differentiation. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Alginate hydrogel and matrigel as potential cell carriers for neurotransplantation
Authors: Novikova Liudmila N. , Mosahebi Afshin , Wiberg Mikael , Terenghi Giorgio , Kellerth Jan‐Olof , Novikov Lev N.
Published: January 2006

Development of biosynthetic conduits carrying extracellular matrix molecules and cell lines expressing neurotrophic growth factors represents a novel and promising strategy for spinal cord and peripheral nerve repair. In the present in vitro study, the compatibility and growth‐promoting effects of (i) alginate hydrogel, (ii) alginate hydrogel complemented with fibronectin, and (iii) matrigel were compared between olfactory ensheathing cells (OECs), Schwann cells (SCs), and bone marrow stromal cells (BMSCs). Neurite outgrowth from embryonic dorsal root ganglia (DRG) neurons was used to assess the efficacy of the hydrogels alone or in combination with cultured cells to promote axonal regeneration. The result showed that alginate hydrogel transformed OECs, SCs, and BMSCs into atypical cells with spherical shape and inhibited their metabolic activity. Combination of alginate hydrogel with fibronectin promoted only OECs proliferation. Alginate hydrogel also inhibited outgrowth of DRG neurites, although this effect was attenuated by addition of fibronectin, SCs, or BMSCs. In contrast, matrigel stimulated cell proliferation, preserved the typical morphological features of the cultured cells and induced massive sprouting of DRG neurites. Addition of cultured cells to matrigel did not further improve DRG neurite outgrowth. The present findings suggest that addition of extracellular matrix should be considered when engineering biosynthetic scaffolds on the basis of alginate hydrogels. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Hydration and dynamic fatigue of dentin
Authors: Arola D. , Zheng W.
Published: January 2006

An experimental investigation on the dynamic fatigue response of dentin was conducted to examine the influence of stress rate on the strength and energy to fracture. Rectangular beams were prepared from the coronal dentin of bovine maxiallary molars and subjected to four‐point flexure to failure. The dentin beams were examined in the fully hydrated and dehydrated condition at stress rates () ranging from 0.01 to 100 MPa/s. Results for the hydrated dentin showed that the flexure strength, energy to fracture, and flexure modulus all increased with increasing stress rate; the flexure strength increased from 100 MPa (() = 0.01 MPa/s) to 250 MPa (() = 100 MPa/s). In contrast, the elastic modulus and strength of the dehydrated dentin decreased with increasing stress rate; the flexural strength of the dehydrated dentin deceased from 170 MPa (() = 0.01 MPa/s) to 100 MPa (() = 100 MPa/s). While the hydrated dentin behaved more like a brittle material at low stress rates, the strain to fracture was found to be nearly independent of (). According to the experimental results, restorative conditions that cause development of static stresses within the tooth could promote a decrease in the damage tolerance of dentin. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Augmentation of acrylic bone cement with multiwall carbon nanotubes
Authors: Marrs Brock , Andrews Rodney , Rantell Terry , Pienkowski David
Published: January 2006

Acrylic bone cement, based on polymethylmethacrylate (PMMA), is a proven polymer having important applications in medicine and dentistry, but this polymer continues to have less than ideal resistance to mechanical fatigue and impact. A variety of materials have been added to bone cement to augment its mechanical strength, but none of these augmentative materials has proven successful. Carbon nanotubes, a new hollow multiwalled tubular material 10–40 nm in diameter, 10–100 μm long, and 50–100 times the strength of steel at 1/6 the weight, have emerged as a viable augmentation candidate because of their large surface area to volume ratio. The objective of this study was to determine if the addition of multiwall carbon nanotubes to bone cement can alter its static or dynamic mechanical properties. Bar‐shaped specimens made from six different (0–10% by weight) concentrations of multiwall carbon nanotubes were tested to failure in quasi‐static 3‐point bending and in 4‐point bending fatigue (5 Hz). Analyses of variance and the 3‐Parameter Weibull model were used to analyze the material performance data. The 2 wt % MWNT concentration enhanced flexural strength by 12.8% (p = 0.003) and produced a 13.1% enhancement in yield stress (p = 0.002). Bending modulus increased slightly with the smaller (<5 wt % MWNT) concentrations, but increased 24.1% (p < 0.001) in response to the 10 wt % loading. While the 2 wt % loading produced slightly improved quasi‐static test results, it was associated with clearly superior fatigue performance (3.3× increase in the Weibull mean fatigue life). Weibull minimum fatigue life (No), Weibull modulus (α), and characteristic fatigue life (β) for bone cement augmented with carbon nanotubes were enhanced versus that observed in the control group. These data unambiguously showed that the bone cement–MWNT polymer system has an enhanced fatigue life compared to “control” bone cement (no added nanotubes). It is concluded that specific multiwall carbon nanotube loadings can favorably improve the mechanical performance of bone cement. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Porcine bladder acellular matrix porosity: Impact of hyaluronic acid and lyophilization
Authors: Cartwright Lisa M. , Shou Zhiping , Yeger Herman , Farhat Walid A.
Published: January 2006

Bladder acellular matrix (ACM) is being investigated as a urinary bladder replacement scaffold. We have demonstrated that ACM is porous and theorized that this contributes to ACM fibrosis and contracture over time in vivo and may preclude uptake and retention of molecules, which may aid cellular repopulation. We sought to determine if hyaluronic acid (HA) would decrease ACM porosity. Porcine ACM was lyophilized and rehydrated in HA (SIGMA) to form the hybrid HA‐ACM construct. Three groups (n = 15/group: HA‐ACM, ACM, and lyophilized/rehydrated ACM) were tested for porosity to a 10 cm column of distilled water, measuring the effluent hourly for 3 h. A porosity index was determined as the total effluent divided by time and area (cc/cm2 hr). Alcian blue staining and fluorophore‐assisted carbohydrate electrophoresis qualitatively and quantitatively confirmed the uptake of HA. HA‐ACM and lyophilized/rehydrated ACM were significantly less porous to water than untreated ACM [mean (±SE): 0.09 (±0.02), 0.74 (±0.4), and 9.8 (±1.6) cc/cm2 hr, respectively; Mann Whitney p < 0.0001 (HA) and p < 0.0001 (lyo)]. The difference between HA‐ACM and lyophilized ACM was also statistically significant (p = 0.014). ACM hybridization with HA decreases ACM porosity, in part because of ACM lyophilization during the hybridization process. In future applications, HA may function as a carrier for smaller molecules such as growth factors, and as a bioactive molecule to improve wound healing and decrease fibrosis in tissue‐engineered bladder constructs. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Differential effect of in vitro degradation on resin–dentin bonds produced by self‐etch versus total‐etch adhesives
Authors: Toledano Manuel , Osorio Raquel , Albaladejo Alberto , Aguilera Fatima S. , Osorio Estrella
Published: January 2006

Objective: To evaluate the effect of an in vitro challenge (NaOCl immersion) on microtensile bond strength (MTBS) of five adhesive systems to dentin. Methods: Flat dentin surfaces from 40 molars were bonded with three total‐etch adhesives (Single Bond, Prime&Bond NT and the experimental Prime&Bond XP), and two self‐etching agents (Clearfil SE Bond and Etch&Prime 3.0). Composite build‐ups were constructed with Tetric Ceram. Teeth were then sectioned into beams of 1.0 mm2 cross‐sectional area. Half of the beams were immersed in 10% NaOCl aqueous solution for 5 h. Each beam was tested in tension in an Instron machine at 0.5 mm/min. Data were analyzed by 2‐way ANOVA and multiple comparisons tests (p < 0.05). Results: Clearfil SE Bond and Single Bond attained higher MTBS than the other three adhesives. Prime&Bond NT and Prime&Bond XP performed equally, and Etch&Prime resulted in the lowest MTBS. After NaOCl immersion, MTBS decreased in all groups. The highest MTBS values were obtained for Clearfil SE Bond and Prime&Bond XP. Scaning electron mycroscopy observation of debonded sticks evidenced dissolution and microstructural alterations of intertubular dentin, except when Clearfil SE Bond was used. Conclusions: Resin–dentin bonds are prone to chemical degradation. The extent of the resin degradation is adhesive system specific. Chemical degradation of the nonresin infiltrated collagen fibers does also exist in total‐etch adhesives. Both processes may reduce long‐term resin–dentin bond strength. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Electroporation‐mediated interleukin‐10 overexpression in skeletal muscle reduces acute rejection in rat cardiac allografts
Authors: Tavakoli Reza , Gazdhar Amiq , Pierog Jaroslaw , Bogdanova Anna , Gugger Mathias , Pringle Ian A , Gill Deborah R. , Hyde Stephen C. , Genoni Michele , Schmid Ralph A.
Published: January 2006

Objectives

Human interleukin 10 (hIL‐10) may reduce acute rejection after organ transplantation. Our previous data shows that electroporation‐mediated transfer of plasmid DNA to peripheral muscle enhances gene transduction dramatically. This study was designed to investigate the effect of electroporation‐mediated overexpression of hIL‐10 on acute rejection of cardiac allografts in the rat.

Methods

The study was designed to evaluate the effect of hIL‐10 gene transfer on (a) early rejection pattern and (b) graft survival. Gene transfer was achieved by intramuscular (i.m.) injection into the tibialis anterior muscle of Fischer (F344) male recipients followed by electroporation 24 h prior to transplantation. Heterotopic cardiac transplantation was performed from male Brown Norway rat to F344. Four groups were studied (n = 6). Treated animals in groups B1 and B2 received 2.5 µg of pCIK hIL‐10 and control animals in groups A1 and A2 distilled water. Graft function was assessed by daily palpation. Animals from group A1 were sacrificed at the cessation of the heart beat of the graft and those in group B1 were sacrificed at day 7; blood was taken for ELISA measurement of hIL‐10 and tissue for myeloperoxidase (MPO) measurement and histological assessment. To evaluate graft survival, groups A2 and B2 were sacrificed at cessation of the heart beat of the graft.

Results

Histological examination revealed severe rejection (IIIB‐IV) in group A1 in contrast to low to moderate rejection (IA‐IIIA) in group B1 (p = 0.02). MPO activity was significantly lower in group B1 compared to group A1 (18 ± 7 vs. 32 ± 14 mU/mg protein, p = 0.05). Serum hIL‐10 levels were 46 ± 13 pg/ml in group B1 vs. 0 pg/ml in group A1. At day 7 all heart allografts in the treated groups B1 and B2 were beating, whereas they stopped beating at 5 ± 2 days in groups A1 and A2 vs. 14 ± 2 days in group B2 (p = 0.0012).

Conclusions

Electroporation‐mediated intramuscular overexpression of hIL‐10 reduces acute rejection and improves survival of heterotopic heart allografts in rats. This study demonstrates that peripheral overexpression of specific genes in skeletal muscle may reduce acute rejection after whole organ transplantation. Copyright © 2006 John Wiley & Sons, Ltd.
Stable RNA interference: comparison of U6 and H1 promoters in endothelial cells and in mouse brain
Authors: Mäkinen Petri I. , Koponen Jonna K. , Kärkkäinen Anna‐Mari , Malm Tarja M. , Pulkkinen Kati H. , Koistinaho Jari , Turunen Mikko P. , Ylä‐Herttuala Seppo
Published: January 2006

Background

RNA interference (RNAi) is a post‐transcriptional RNA degradation process, which has become a very useful tool in gene function studies and gene therapy applications. Long‐term cellular expression of small interfering RNA (siRNA) molecules required for many gene therapy applications can be achieved by lentiviral vectors (LVs). The two most commonly used promoters to drive the short hairpin RNA (shRNA) expression are the human U6 small nuclear promoter (U6) and the human H1 promoter (H1).

Methods

We investigated whether there is any significant difference between the efficiencies of U6 and H1 in LV‐mediated RNAi using green fluorescent protein (GFP) as a target gene by flow cytometry and real‐time reverse‐transcription polymerase chain reaction (RT‐PCR) in endothelial cells. Also, we compared the efficiencies of U6 and H1 in the GFP transgenic mouse brain after stereotactic LV injection.

Results

We show that the U6 promoter is more efficient than H1 in GFP silencing in vitro, leading to 80% GFP knockdown at an average of one integrated vector genome per target cell genome. The silencing is persistent for several months. In addition, the U6 promoter is superior to H1 in vivo and leads to stable GFP knockdown in mouse brain for at least 9 months.

Conclusions

These results show that LV‐mediated RNAi is a powerful gene‐silencing method for the long‐term inhibition of gene expression in vitro and in vivo. Copyright © 2006 John Wiley & Sons, Ltd.
Lentiviral gene delivery to CNS by spinal intrathecal administration to neonatal mice
Authors: Fedorova Elena , Battini Lorenzo , Prakash‐Cheng Ainu , Marras Daniele , Gusella G. Luca
Published: January 2006

Background

Direct injection of lentivectors into the central nervous system (CNS) mostly results in localized parenchymal transgene expression. Intrathecal gene delivery into the spinal canal may produce a wider dissemination of the transgene and allow diffusion of secreted transgenic proteins throughout the cerebrospinal fluid (CSF). Herein, we analyze the distribution and expression of LacZ and SEAP transgenes following the intrathecal delivery of lentivectors into the spinal canal.

Methods

Four weeks after intrathecal injection into the spinal canal of newborn mice, the expression of the LacZ gene was assessed by histochemical staining and by in situ polymer chain reaction (PCR). Following the spinal infusion of a lentivector carrying the SEAP gene, levels of enzymatically active SEAP were measured in the CSF, blood serum, and in brain extracts.

Results

Intrathecal spinal canal delivery of lentivectors to newborn mice resulted in patchy, widely scattered areas of β‐gal expression mostly in the meninges. The transduction of the meningeal cells was confirmed by in situ PCR. Following the spinal infusion of a lentivector carrying the SEAP gene, sustained presence of the reporter protein was detected in the CSF, as well as in blood serum, and brain extracts.

Conclusions

These findings indicate that intrathecal injections of lentivectors can provide significant levels of transgene expression in the meninges. Unlike intracerebral injections of lentivectors, intrathecal gene delivery through the spinal canal appears to produce a wider diffusion of the transgene. This approach is less invasive and may be useful to address those neurological diseases that benefit from the ectopic expression of soluble factors impermeable to the blood‐brain barrier. Copyright © 2006 John Wiley & Sons, Ltd.
Protection against influenza infection by cytokine‐enhanced aerosol genetic immunization
Authors: Orson Frank M. , Kinsey Berma M. , Densmore Charles L. , Nguyen Tina , Wu Yan , Mbawuike Innocent N. , Wyde Philip R.
Published: January 2006

Background

Conventional vaccine development for newly emerging pandemic influenza virus strains would likely take too long to prevent devastating global morbidity and mortality. If DNA vaccines can be distributed and delivered efficiently, genetic immunization could be an attractive solution to this problem, since plasmid DNA is stable, easily engineered to encode new protein antigens, and able to be quickly produced in large quantities.

Methods

We compared two novel genetic immunization methods in a mouse model of influenza to evaluate protective effects: aerosol delivery of polyethylenimine (PEI)‐complexed hemagglutinin (HA)‐expressing plasmid and intravenous (IV) delivery of the plasmid complexed with macroaggregated albumin/PEI. Serial serum samples were obtained for assay of neutralizing antibodies against HA. Mice were then challenged in the airway with influenza virus, and production of infectious virus in the lungs was titered.

Results

Most mice immunized with HA plasmid alone by aerosol and all mice immunized IV developed protective immune responses, whereas none administered control plasmid were protected. Aerosol co‐administration of HA plasmid with plasmids encoding the cytokines interleukin 12 (IL12) and granulocyte‐macrophage colony stimulating factor (GM‐CSF) markedly increased neutralizing antibody responses, so that all aerosol immunized mice were protected from high level virus proliferation.

Conclusions

Cytokine‐enhanced aerosol delivery of plasmid vaccines can elicit robust protective immune responses against influenza. Thus, aerosol delivery has the potential to address the need for rapid widespread immunization against new influenza virus strains, and may have applications for other infectious and toxic disease processes. Copyright © 2006 John Wiley & Sons, Ltd.
Adrenomedullin gene transfer induces neointimal apoptosis and inhibits neointimal hyperplasia in injured rat artery
Authors: Rauma‐Pinola Tanja , Pääkkö Paavo , Ilves Mika , Serpi Raisa , Romppanen Hannu , Vuolteenaho Olli , Ruskoaho Heikki , Hautala Timo
Published: January 2006

Arterial wall injury leads to inflammatory reaction and release of growth factors that may mediate intimal regrowth. It is hypothesized that the neointimal cells may originate from adventitial myofibroblasts, medial smooth muscle cells, or differentiated bone marrow derived cells. Adrenomedullin (AM), an auto/paracrine cardiovascular peptide that is secreted from fibroblasts, endothelial cells, and vascular smooth muscle cells, may have a regulatory role in the intimal regeneration. In order to investigate the role of AM in neointimal growth, stimulation of stem cell migration, and apoptosis, we overexpressed AM with recombinant adenovirus in a rat arterial injury model. The intimae were significantly thinner in the arteries treated with AM adenovirus compared to the control group. Intima/media ratios were 0.48 ± 0.18 and 1.01 ± 0.20 (P < 0.05) in the AM group and the control group, respectively. In addition, a significantly higher apoptotic index of neointimal cells was seen in the AM gene transfer group compared to the control (2.78 ± 0.5 vs. 0.57 ± 0.20, P < 0.01). The neointimal cells stained positive for α‐smooth muscle actin and negative for desmin suggesting possible myofibroblast origin. Very few c‐Kit+ or MDR1+ cells were detected 2 weeks after the injury. We conclude that AM overexpression inhibits neointimal growth. The inhibition is associated with enhanced apoptosis of the neointimal cells which may be of myofibroblast origin. Copyright © 2006 John Wiley & Sons, Ltd.
A convenient plasmid system for construction of helper‐dependent adenoviral vectors and its application for analysis of the breast‐cancer‐specific mammaglobin promoter
Authors: Shi Chang‐Xin , Graham Frank L. , Hitt Mary M.
Published: January 2006

Background

Helper‐dependent (HD) adenovirus (Ad) vectors, deleted of all viral coding sequences, have a higher cloning capacity, improved performance of tissue‐specific promoters, and reduced toxicity in animals relative to first‐generation Ad vectors, making these vectors promising tools for gene transfer in vitro and in vivo. However, the large size of HDAd precursor plasmids renders them relatively difficult to manipulate due to the paucity of unique restriction enzyme sites suitable for transgene insertion and to the size constraints imposed by the viral packaging machinery.

Methods

We have constructed a series of HDAd precursor plasmids that allows cassette insertion at a unique site in the vector backbone. We have tested whether these vector backbones will support the tissue‐specificity of inserted expression cassettes in a study of the activity of the potentially breast‐cancer‐specific mammaglobin promoter and enhancer.

Results

We report here the generation of a series of HDAd precursor plasmids, both with and without an additional reporter expression cassette, that were designed to accommodate a wide range in size of inserted DNA. The system was validated for transcriptional targeting studies by demonstrating the tissue‐specificity and activity of the mammaglobin promoter rescued using this precursor system. In addition, we have extended our previous studies on the mammaglobin promoter by demonstrating that two copies of the mammaglobin enhancer fused to the minimal promoter surpassed the activity of the single enhancer/promoter by at least 10‐fold in breast cancer cells while maintaining only minimal expression in normal cells both in vitro and in a mouse tumor model.

Conclusions

This versatile plasmid system simplifies the construction of HDAd vectors and was valuable in demonstrating the targeting potential of the mammaglobin promoter for breast cancer gene therapy. Copyright © 2006 John Wiley & Sons, Ltd.
Chitosan‐g‐PEG/DNA complexes deliver gene to the rat liver via intrabiliary and intraportal infusions
Authors: Jiang Xuan , Dai Hui , Leong Kam W. , Goh Suat‐Hong , Mao Hai‐Quan , Yang Yi‐Yan
Published: January 2006

Background

Chitosan has been shown to be a non‐toxic and efficient vector forin vitrogene transfection andin vivogene delivery through pulmonary and oral administrations. Recently, we have shown that chitosan/DNA nanoparticles could mediate high levels of gene expression following intrabiliary infusion1. In this study, we have examined the possibility of using polyethylene glycol (PEG)‐grafted chitosan/DNA complexes to deliver genes to the liver through bile duct and portal vein infusions.

Methods

PEG (Mw: 5 kDa) was grafted onto chitosan (Mw: 47 kDa, deacetylation degree: 94%) with grafting degrees of 3.6% and 9.6% (molar percentage of chitosan monosaccharide units grafted with PEG). The stability of chitosan‐g‐PEG/DNA complexes was studied by measuring the change in particle size and by agarose gel electrophoresis against bile or serum challenge. The influence of PEG grafting on gene transfection efficiency was evaluated in HepG2 cells using luciferase reporter gene. Chitosan and chitosan‐g‐PEG/DNA complexes were delivered to the liver through bile duct and portal vein infusions with a syringe pump. Gene expression in the liver and the distribution of gene expression in other organs were evaluated. The acute liver toxicity of chitosan and chitosan‐g‐PEG/DNA complexes was examined by measuring serum alanine aminotranferase (ALT) and aspartate aminotransferase (AST) activities as a function of time.

Results

Both chitosan and chitosan‐g‐PEG displayed comparable gene transfection efficiency in HepG2 cells. After challenge with serum and bile, chitosan‐g‐PEG/DNA complexes, especially those prepared with chitosan‐g‐PEG (GD = 9.6%), did not form large aggregates like chitosan/DNA complexes but remained stable for up to 30 min. In addition, chitosan‐g‐PEG prevented the degradation of DNA in the presence of serum and bile. On day 3 after bile duct infusion, chitosan‐g‐PEG (GD = 9.6%)/DNA complexes mediated three times higher gene expression in the liver than chitosan/DNA complexes and yielded background levels of gene expression in other organs. On day 1 following portal vein infusion, gene expression level induced by chitosan/DNA complexes was hardly detectable but chitosan‐g‐PEG (GD = 9.6%) mediated significant transgene expression. Interestingly, transgene expression by chitosan‐g‐PEG/DNA complexes in other organs after portal vein infusion increased with increasing grafting degree of PEG. The ALT and AST assays indicated that grafting of PEG to chitosan reduced the acute liver toxicity towards the complexes.

Conclusion

This study demonstrated the potential of chitosan‐g‐PEG as a safe and more stable gene carrier to the liver. Copyright © 2006 John Wiley & Sons, Ltd.