bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Harvest Treatment on Biochemical Properties of Farmed Chinook Salmon (Oncorhynchus tshawytscha) Tissue during Frozen and Thawed Storage
Authors: Cook D.G. , Holland A.J. , Jerrett A.R. , Forster M.E.
Published: July 2009

ABSTRACT:  Two different harvest procedures were employed to investigate whether the method of harvest has an effect upon deteriorative processes that occur during the frozen storage of Chinook salmon (Oncorhynchus tshawytscha) white muscle tissue. These 2 harvest methods, termed “rested”—involving sedation with the aquatic anesthetic AQUI‐S™ and “exercised”—a simulated conventional harvest not involving sedation, contrasted levels of activity of the animal prior to and upon slaughter. Rested and exercised harvesting protocols produced tissue in significantly different postmortem physiological states prior to freezing. Rested, postharvest tissue maintained high metabolic energy stores of ATP and glycogen within the tissue, with low concentrations of tissue and plasma lactate. Exercised tissue exhibited near depleted concentrations of ATP and glycogen and a marked lactate accumulation. In both treatments, no significant change in metabolite levels was seen over a 6‐mo storage period at −19 °C when tissue was frozen immediately postharvest. Transfer of tissue from frozen temperatures (−80 and −19 °C), to refrigerated (−1 and +4 °C, respectively) resulted in rapid glycolysis, depleting tissue ATP and glycogen stores and increasing tissue lactate concentrations. Metabolic activity was more significant in rested tissue owing to the larger concentrations of metabolic energy stores and occurred at temperatures between −3 and −1.5 °C. During frozen storage (−19 °C), there was an increase in the secondary lipid oxidation product TBARS, but harvest treatment had no effect. However, following transfer from frozen to refrigerated (+4 and −1 °C) storage, rested tissue showed a significant ability to retard the development of TBARS products.
α‐Priori and α‐Posterior Dietary Pattern Analyses Have Similar Estimating and Discriminating Ability in Predicting 5‐Y Incidence of Cardiovascular Disease: Methodological Issues in Nutrition Assessment
Authors: Panagiotakos Demosthenes B. , Pitsavos Christos , Stefanadis Christodoulos
Published: July 2009

ABSTRACT:  The 5‐y incidence of cardiovascular disease (CVD) in relation to dietary habits was evaluated, using 2 methodological approaches, an α‐priori and an α‐posterior diet pattern analyses. The aim of this study was to compare these methods in predicting CVD events. From May 2001 to December 2002, 3042 men and women (>18 y) without any clinical evidence of CVD were enrolled in the ATTICA study. In 2006, the 5‐y follow‐up was performed (941 of the 3042 [31%] participants were lost to follow‐up). Development of CVD (coronary heart disease, acute coronary syndromes, stroke, or other CVD) during the follow‐up period was defined according to WHO‐ICD‐10 criteria. An α‐posterior statistical method, principal component analysis (PCA), was applied to extract dietary patterns from various foods or food groups. Moreover, a special diet score that incorporates inherent characteristics of the Mediterranean diet (the MedDietScore) was also used to assess level of adherence to this diet (α‐priori approach). Using PCA 10 components were extracted that explained the 57% of the total variation in intake. The model that also included various potential confounders together with the extracted components showed adequate goodness of fit and very good discriminating ability (C‐statistic = 0.85). The other model that included the same potential confounders together with the MedDietScore also showed adequate goodness of fit and very good discriminating ability, too (C‐statistic = 0.83). α‐priori and α‐posterior dietary assessment showed similar estimating and discriminating ability in predicting CVD, in our sample.
Irradiation of Skin and Contrasting Effects on Absorption of Hydrophilic and Lipophilic Compounds
Authors: Duracher Lucie , Blasco Laurent , Abdel Jaoued Aïda , Vian Laurence , Marti‐Mestres Gilberte
Published: July 2009

Increasing legal requirements for risk assessment and efficacy testing in the dermo‐cosmetic field have led to the development of alternative test methods. In this study, the porcine skin model was chosen to test the effect of irradiation on the penetration habits of UV filters and caffeine. For decades, the pig has been recognized as an experimental animal in biomedical research thanks to its morphological and physiological similarities to humans. In this study, we wanted to investigate the effect of UV irradiation on the absorption of octocrylene (OC) and benzophenone‐3 (B3) sunscreens used under those circumstances and a model hydrophilic molecule, caffeine (Caf). These particular compounds were chosen due to their different lipophilic profiles. The percutaneous penetration of the two UV filters and Caf was studied after two simulated solar radiation doses of 61.4 kJ m−2. After irradiation simulation, the total absorbed dose was increased for OC while for B3 and Caf it was lower. Thus, modifications in percutaneous absorption have been observed, and it appears that UV could play a crucial role in this process. Moreover, it has been observed that the lipophilic profile of the studied compounds affects percutaneous penetration when irradiated.
DNA Damage and Apoptosis Induced by Photosensitization of 5,10,15,20‐Tetrakis (N‐methyl‐4‐pyridyl)‐21H,23H‐porphyrin via Singlet Oxygen Generation
Authors: Tada‐Oikawa Saeko , Oikawa Shinji , Hirayama Junya , Hirakawa Kazutaka , Kawanishi Shosuke
Published: July 2009

Cancer photodynamic therapy (PDT) requires photosensitizers that efficiently and selectively destroy tumor cells. We investigated 5,10,15,20‐tetrakis (N‐methyl‐4‐pyridyl)‐21H,23H‐porphyrin (TMPyP) as a potential cancer treatment. Confocal fluorescence microscopy showed that TMPyP was localized in the nuclei, whereas 5‐aminolevulinic acid (ALA)‐derived protoporphyrin IX (PPIX) was localized diffusely in the cytoplasm of human leukemia (HL‐60) cells. In HL‐60 cells under UVA irradiation, TMPyP effectively induced apoptosis. Moreover, 8‐oxo‐7,8‐dihydro‐2′‐deoxyguanosine, an oxidative product of 2′‐deoxyguanosine, was accumulated in the DNA of cells treated with photoirradiated TMPyP, whereas only small amounts were observed in ALA‐treated cells in the presence of UVA light. TMPyP and UVA caused extensive damage at every guanine residue in DNA fragments obtained from the human p53 tumor suppressor gene and the c‐Ha‐ras‐1 proto‐oncogene, whereas PPIX induced little DNA damage under these conditions. Electron spin resonance spectroscopy using a singlet oxygen (1O2) probe and D2O showed that photoexcited TMPyP generated 1O2. These results suggest that photoexcited TMPyP reacts with oxygen to generate 1O2, which in turn, oxidizes guanine residues. Taken together, the results demonstrated that TMPyP was localized in the nucleus where it was photosensitized to induce DNA damage, suggesting that TMPyP may have clinical utility as a nucleus‐targeted PDT.
Cotransplantation of HLA‐identical mesenchymal stem cells and hematopoietic stem cells in Chinese patients with hematologic diseases
Authors: ZHANG X. , LI J.‐Y , CAO K. , LU H. , HONG M. , QIAN S. , WU H. , LIU P. , XU W.
Published: July 2009

Mesenchymal stem cells (MSCs) may be employed to support hematopoietic reconstitution and mitigate graft‐vs.‐host disease (GVHD) in transplantation of hematopoietic stem cells (HSCs). The aim of this study was to explore the feasibility and safety of cotransplantation culture‐expanded MSCs and HSCs from the same human leukocyte antigen (HLA)‐identical sibling donor in Chinese patients with hematologic diseases. Bone marrow mononuclear cells from healthy donors were cultured and expanded ex vivo. Immunophenotype, adipogenic and osteogenic differentiation potential, and karyotype of the harvested MSCs were detected on those who had been cotransplanted with HSCs and MSCs from the same donor. Hematopoietic reconstitutions, complications, and clinical outcomes were observed after cotransplantation in these patients. (1.77 ± 0.40) × 106/kg (donor’s weight) MSCs were successfully expanded from 23.6 ± 5.96 ml of bone marrow samples. They had normal karyotypes with bi‐lineages differentiation potential, and were CD73, CD90, and CD105 positive. Twelve patients underwent cotransplantation with no observable adverse response during and after the infusion of MSCs. Hematopoietic reconstitutions were rapid. Two patients developed grade II–IV acute GVHD, and two extensive chronic GVHD. Four patients suffered from cytomegalovirus infection but were cured eventually. Up to now, seven patients have been followed as long as 29–57 months and five patients died. It is concluded that MSCs can be expanded effectively by culture and it is safe and feasible to cotransplant patients with allogenic culture‐expanded MSCs and HSCs.
Calcium buffering in rodent olfactory bulb granule cells and mitral cells
Authors: Egger Veronica , Stroh Olga
Published: July 2009

In the mammalian olfactory bulb, axonless granule cells (GCs) mediate self‐ and lateral inhibitory interactions between mitral cells (MCs) via reciprocal dendrodendritic synapses. Calcium signals in the GC dendrites and reciprocal spines appear to decay unusually slowly, hence GC calcium handling might contribute to the known asynchronous release at this synapse. By recording fluorescence transients of different Ca2+‐sensitive dyes at variable concentrations evoked by backpropagating action potentials (APs) and saturating AP trains we extrapolated Ca2+ dynamics to conditions of zero added buffer for juvenile rat GC apical dendrites and spines and MC lateral dendrites. Resting [Ca2+] was at ∼50 nm in both GC dendrites and spines. The average endogenous GC buffer capacities (κE) were within a range of 80–90 in the dendrites and 110–140 in the spines. The extrusion rate (γ) was estimated as 570 s−1 for dendrites and 870 s−1 for spines and the decay time constant as ∼200 ms for both. Single‐current‐evoked APs resulted in a [Ca2+] elevation of ∼250 nm. Calcium handling in juvenile and adult mouse GCs appeared mostly similar. In MC lateral dendrites, we found AP‐mediated [Ca2+] elevations of ∼130 nm with a similar decay to that in GC dendrites, while κE and γ were roughly 4‐fold higher. In conclusion, the slow GC Ca2+ dynamics are due mostly to sluggish Ca2+ extrusion. Under physiological conditions this slow removal may well contribute to delayed release and also feed into other Ca2+‐dependent mechanisms that foster asynchronous output from the reciprocal spine.
Strain-Dependent Oxygen Diffusivity in Bovine Annulus Fibrosus
Authors: Yuan T.-Y. , Jackson A. R. , Huang C.-Y. , Gu W. Y.
Published: July 2009

The intervertebral disk (IVD) is the largest avascular structure in the human body. Transport of small molecules in IVD is mainly through diffusion from the endplates and the peripheral blood vessels surrounding IVD. Studies have investigated the structure, chemical components, and water content in IVD, but to our knowledge no study has investigated the effect of mechanical loading on oxygen transport in IVD. The objective of this study was to determine the strain-dependent behavior of oxygen diffusivity in IVD tissue. A one-dimensional steady-state diffusion experiment was designed and performed to determine the oxygen diffusivity in bovine annulus fibrosus (AF). The oxygen diffusivity was calculated using equation derived from Fick’s law. A total of 20 AF specimens (d=6 mm, h∼0.5 mm) from bovine coccygeal IVD were used to determine oxygen diffusivity at three levels of compressive strain. The average oxygen diffusivity (mean±SD) of bovine AF in the axial direction was 1.43±0.242×10−5 cm2/s(n=20) at 4.68±1.67% compressive strain level, 1.05±0.282×10−5 cm2/s(n=20) at 14.2±1.50% strain level, and 7.71±1.63×10−6 cm2/s(n=20) at 23.7±1.34% strain level. There was a significant decrease in oxygen diffusivity with increasing level of compressive strain (ANOVA, p<0.05). Oxygen diffusivity of bovine AF in the axial direction has been determined. The mechanical loading has a significant effect on oxygen transport in IVD tissues. This study is important in understanding nutritional transport in IVD tissues and related disk degeneration.
The Deformation Behavior of Multiple Red Blood Cells in a Capillary Vessel
Authors: Gong Xiaobo , Sugiyama Kazuyasu , Takagi Shu , Matsumoto Yoichiro
Published: July 2009

The deformation of multiple red blood cells in a capillary flow was studied numerically. The immersed boundary method was used for the fluid red blood cells interaction. The membrane of the red blood cell was modeled as a hyperelastic thin shell. The numerical results show that the apparent viscosity in the capillary flow is more sensitive to the change of shear coefficient of the membrane than the bending coefficient and surface dilation coefficient, and the increase in the shear coefficient results in an increase in the pressure drop in the blood flow in capillary vessels in order to sustain the same flux rate of red blood cells.
Model for Heat and Mass Transfer in Freeze-Drying of Pellets
Authors: Trelea Ioan Cristian , Passot Stéphanie , Marin Michèle , Fonseca Fernanda
Published: July 2009

Lyophilizing frozen pellets, and especially spray freeze-drying, have been receiving growing interest. To design efficient and safe freeze-drying cycles, local temperature and moisture content in the product bed have to be known, but both are difficult to measure in the industry. Mathematical modeling of heat and mass transfer helps to determine local freeze-drying conditions and predict effects of operation policy, and equipment and recipe changes on drying time and product quality. Representative pellets situated at different positions in the product slab were considered. One-dimensional transfer in the slab and radial transfer in the pellets were assumed. Coupled heat and vapor transfer equations between the temperature-controlled shelf, the product bulk, the sublimation front inside the pellets, and the chamber were established and solved numerically. The model was validated based on bulk temperature measurement performed at two different locations in the product slab and on partial vapor pressure measurement in the freeze-drying chamber. Fair agreement between measured and calculated values was found. In contrast, a previously developed model for compact product layer was found inadequate in describing freeze-drying of pellets. The developed model represents a good starting basis for studying freeze-drying of pellets. It has to be further improved and validated for a variety of product types and freeze-drying conditions (shelf temperature, total chamber pressure, pellet size, slab thickness, etc.). It could be used to develop freeze-drying cycles based on product quality criteria such as local moisture content and glass transition temperature.
A Preliminary Study to Delineate Irreversible Electroporation From Thermal Damage Using the Arrhenius Equation
Authors: Shafiee Hadi , Garcia Paulo A. , Davalos Rafael V.
Published: July 2009

Intense but short electrical fields can increase the permeability of the cell membrane in a process referred to as electroporation. Reversible electroporation has become an important tool in biotechnology and medicine. The various applications of reversible electroporation require cells to survive the procedure, and therefore the occurrence of irreversible electroporation (IRE), following which cells die, is obviously undesirable. However, for the past few years, IRE has begun to emerge as an important minimally invasive nonthermal ablation technique in its own right as a method to treat tumors and arrhythmogenic regions in the heart. IRE had been studied primarily to define the upper limit of electrical parameters that induce reversible electroporation. Thus, the delineation of IRE from thermal damage due to Joule heating has not been thoroughly investigated. The goal of this study was to express the upper bound of IRE (onset of thermal damage) theoretically as a function of physical properties and electrical pulse parameters. Electrical pulses were applied to THP-1 human monocyte cells, and the percentage of irreversibly electroporated (dead) cells in the sample was quantified. We also determined the upper bound of IRE (onset of thermal damage) through a theoretical calculation that takes into account the physical properties of the sample and the electric pulse characteristics. Our experimental results were achieved below the theoretical curve for the onset of thermal damage. These results confirm that the region to induce IRE without thermal damage is substantial. We believe that our new theoretical analysis will allow researchers to optimize IRE parameters without inducing deleterious thermal effects.
Modeling Heat Shock Protein Expression Produced by a Heat Wrap
Authors: Song Alfred S. , Diller Kenneth R.
Published: July 2009

The healing effect of therapeutic hyperthermia induced by widely available heat wrap products is understood to be based on concomitant temperature dependent vasodilation and increase in mass transport. We hypothesize that an additional mechanism of healing associated with increased heat shock protein (HSP) expression is also a contributing factor. HSP expression is controlled by the level and duration of heating and can have a potent effect on healing. We have developed a combined thermal stress and HSP expression model for bioheat transport into the tissues of the back produced by a therapeutic heat wrap. The model predicts temperature distribution in the deep tissues of the back by a modified version of the Pennes (1948, “Analysis of Tissue and Arterial Blood Temperatures in the Resting Human Forearm,” J. Appl. Physiol., 1(2), pp. 93–122) bioheat equation. The model also predicts HSP70/actin concentrations based on existing empirical expression data from our laboratory as a function of heating time and temperature. Thermal boundary conditions were input for a typical heat wrap worn for its functional duration of 8 h or more. Temperatures in the paraspinal muscles of the back increase by a minimum of 1°C after 1 h of heating and persist for at least 2 h. HSP70/actin expression is increased 1.7-fold above the control. The model demonstrates that elevated HSP expression may provide an important contribution to the healing process in injured tissue when a therapeutic heat wrap is worn.
Effect of Controlled Ice Nucleation on Primary Drying Stage and Protein Recovery in Vials Cooled in a Modified Freeze-Dryer
Authors: Passot Stéphanie , Tréléa Ioan Cristian , Marin Michèle , Galan Miquel , Morris G. John , Fonseca Fernanda
Published: July 2009

The freezing step influences lyophilization efficiency and protein stability. The main objective of this work was to investigate the impact on the primary drying stage of an ultrasound controlled ice nucleation technology, compared with usual freezing protocols. Lyophilization cycles involving different freezing protocols (applying a constant shelf cooling rate of 1°C/min or 0.2°C/min, putting vials on a precooled shelf, and controlling nucleation by ultrasounds or by addition of a nucleating agent) were performed in a prototype freeze-dryer. Three protective media including sucrose or maltodextrin and differing by their thermal properties and their ability to preserve a model protein (catalase) were used. The visual aspect of the lyophilized cake, residual water content, and enzymatic activity recovery of catalase were assessed after each lyophilization cycle and after 1 month of storage of the lyophilized product at 4°C and 25°C. The freezing protocols allowing increasing nucleation temperature (precooled shelf and controlled nucleation by using ultrasounds or a nucleating agent) induced a faster sublimation step and higher sublimation rate homogeneity. Whatever the composition of the protective medium, applying the ultrasound technology made it possible to decrease the sublimation time by 14%, compared with the freezing method involving a constant shelf cooling rate of 1°C/min. Concerning the enzyme activity recovery, the impact of the freezing protocol was observed only for the protective medium involving maltodextrin, a less effective protective agent than sucrose. Higher activity recovery results were obtained after storage when the ultrasound technology or the precooled shelf method was applied. Controlling ice nucleation during the freezing step of the lyophilization process improved the homogeneity of the sublimation rates, which will, in turn, reduce the intervial heterogeneity. The freeze-dryer prototype including the system of controlled nucleation by ultrasounds appears to be a promising tool in accelerating sublimation and improving intrabatch homogeneity.
Evaluation of Effectiveness of Er,Cr:YSGG Laser For Root Canal Disinfection: Theoretical Simulation of Temperature Elevations in Root Dentin
Authors: Zhu L. , Tolba M. , Arola D. , Salloum M. , Meza F.
Published: July 2009

Erbium, chromium: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) lasers are currently being investigated for disinfecting the root canal system. Prior to using laser therapy, it is important to understand the temperature distribution and to assess thermal damage to the surrounding tissue. In this study, a theoretical simulation using the Pennes bioheat equation is conducted to evaluate how heat spreads from the canal surface using an Er,Cr:YSGG laser. Results of the investigation show that some of the proposed treatment protocols for killing bacteria in the deep dentin are ineffective, even for long heating durations. Based on the simulation, an alternative treatment protocol is identified that has improved effectiveness and is less likely to introduce collateral damage to the surrounding tissue. The alternative protocol uses 350 mW laser power with repeating laser tip movement to achieve bacterial disinfection in the deep dentin (800 μm lateral from the canal surface), while avoiding thermal damage to the surrounding tissue (T<47°C). The alternative treatment protocol has the potential to not only achieve bacterial disinfection of deep dentin but also shorten the treatment time, thereby minimizing potential patient discomfort during laser procedures.
Encapsulation of Living Cells in Small (∼100 μm) Alginate Microcapsules by Electrostatic Spraying: A Parametric Study
Authors: Zhang Wujie , He Xiaoming
Published: July 2009

A parametric study was performed to understand the effect of preparation parameters on size, morphology, and encapsulation efficiency (i.e., cells/microcapsule) of alginate microcapsules prepared using the electrostatic spray method. The preparation parameters studied include sodium alginate concentration, spray voltage, flow rate, and cell density. It was found that both the flow rate and spray voltage have a significant impact on microcapsule size while the microcapsule morphology is greatly influenced by both the sodium alginate concentration and spray voltage. To obtain small (∼100 μm) cell-loaded microcapsules with good morphology (i.e., round in shape and uniform in size) and high encapsulation efficiency (>5 cells/microcapsule), the optimal ranges of spray voltage, flow rate, alginate concentration, and cell density are from 1.6–1.8 kV, 1.5–3 ml/h, >1.5% (w/v), and (3–5)×106 cells/ml, respectively. Under optimal preparation conditions, cells were found to survive the microencapsulation process well.
Adjuvant Approaches to Enhance Cryosurgery
Authors: Goel Raghav , Anderson Kyle , Slaton Joel , Schmidlin Franz , Vercellotti Greg , Belcher John , Bischof John C.
Published: July 2009

Molecular adjuvants can be used to enhance the natural destructive mechanisms of freezing within tissue.  This review discusses their use in the growing field of combinatorial or adjuvant enhanced cryosurgery for a variety of disease conditions.  Two important motivations for adjuvant use are:  (1) increased control of the local disease in the area of freezing (i.e., reduced local recurrence of disease) and (2) reduced complications due to over-freezing into adjacent tissues (i.e., reduced normal functional tissue destruction near the treatment site).  This review starts with a brief overview of cryosurgical technology including probes and cryogens and major mechanisms of cellular, vascular injury and possible immunological effects due to freeze-thaw treatment in vivo.  The review then focuses on adjuvants to each of these mechanisms that make the tissue more sensitive to freeze-thaw injury. Four broad classes of adjuvants are discussed including:  thermophysical agents (eutectic forming salts and amino acids), chemotherapuetics, vascular agents and immunomodulators.  The key issues of selection, timing, dose and delivery of these adjuvants are then elaborated. Finally, work with a particularly promising vascular adjuvant, TNF-alpha, that shows the ability to destroy all cancer within a cryosurgical iceball is highlighted.
Structural Changes in Confined Lysozyme
Authors: Reátegui Eduardo , Aksan Alptekin
Published: July 2009

Proteins and enzymes can be encapsulated in nanoporous gels to develop novel technologies for biosensing, biocatalysis, and biosynthesis. When encapsulated, certain macromolecules retain high levels of activity and functionality and are more resistant to denaturation when exposed to extremes of pH and temperature. We have utilized intrinsic fluorescence and Fourier transform infrared spectroscopy to determine the structural transitions of encapsulated lysozyme in the range of −120°C<T<100°C. At cryogenic temperatures encapsulated lysozyme did not show cold denaturation, instead became more structured. However, at high temperatures, the onset of heat denaturation of confined lysozyme was reduced by 15°C when compared with lysozyme in solution. Altered dynamics of the solvent and pore size distribution of the nanopores in the matrix appear to be key factors influencing the decrease in the denaturation temperature.
Oxygen Transport in Brain Tissue
Authors: Masamoto Kazuto , Tanishita Kazuo
Published: July 2009

Oxygen is essential to maintaining normal brain function. A large body of evidence suggests that the partial pressure of oxygen (pO2) in brain tissue is physiologically maintained within a narrow range in accordance with region-specific brain activity. Since the transportation of oxygen in the brain tissue is mainly driven by a diffusion process caused by a concentration gradient of oxygen from blood to cells, the spatial organization of the vascular system, in which the oxygen content is higher than in tissue, is a key factor for maintaining effective transportation. In addition, a local mechanism that controls energy demand and blood flow supply plays a critical role in moment-to-moment adjustment of tissue pO2 in response to dynamically varying brain activity. In this review, we discuss the spatiotemporal structures of brain tissue oxygen transport in relation to local brain activity based on recent reports of tissue pO2 measurements with polarographic oxygen microsensors in combination with simultaneous recordings of neural activity and local cerebral blood flow in anesthetized animal models. Although a physiological mechanism of oxygen level sensing and control of oxygen transport remains largely unknown, theoretical models of oxygen transport are a powerful tool for better understanding the short-term and long-term effects of local changes in oxygen demand and supply. Finally, emerging new techniques for three-dimensional imaging of the spatiotemporal dynamics of pO2 map may enable us to provide a whole picture of how the physiological system controls the balance between demand and supply of oxygen during both normal and pathological brain activity.
Synthesis of silicon-containing materials for UV-curable imprint etch barrier solutions
Authors: Song Sun-Sik , Kim Sang-Mook , Choi Byung-Yeon , Jung Gun-Young , Lee Heon
Published: July 2009

Silicon-containing acrylate and vinyl-ether derivatives, i.e., bis-(acryloxyethyloxy)-dimethylsilane, bis-(acryloxyethyloxy)-bis-(trimethylsilylmethyl)-silane, and bis-(vinyloxyethyloxy)- dimethylsilane, were synthesized. These materials, together with Irgacure 184 as a radical photoinitiator, were used as components for UV-curable imprint etch barrier (IEB) solutions. The effects of each material on the imprint properties of the IEB solution, such as viscosity and dry-etching resistance, were evaluated. The etch resistance of cured IEB films against oxygen plasma increased with the amount of silicon in the synthesized material. The vinyl-ether derivative had a much lower viscosity than the acrylate derivative. Formulations based on the three synthesized materials were made to find the optimum composition among them in terms of the required properties for the nanoimprinting and the following processes. The optimized formulation was applied to the nanoimprinting and subsequent lift-off process to define nanoscale features of eight chrome (Cr) metal lines with 65 nm linewidth at 250 nm pitch.
Vowel and consonant contributions to vocal tract shape
Authors: Story Brad H.
Published: July 2009

The purpose of this study was to develop a method by which a vowel-consonant-vowel (VCV) utterance based on x-ray microbeam articulatory data could be separated into a vowel-to-vowel transition and a consonant superposition function. The result is a model that represents a vowel sequence as a time-dependent perturbation of the neutral vocal tract shape governed by coefficients of canonical deformation patterns. Consonants were modeled as superposition functions that can force specific portions of the vocal tract shape to be constricted or expanded, over a specific time course. The three VCVs [əpɑ], [ətɑ], and [əkɑ], produced by one female speaker, were analyzed and reconstructed with the developed model. They were shown to be reasonable approximations of the original VCVs, as assessed qualitatively by visual inspection and quantitatively by calculating rms error and correlation coefficients. This establishes a method for future modeling of other speech material.
Deep seafloor arrivals: An unexplained set of arrivals in long-range ocean acoustic propagation
Authors: Stephen Ralph A. , Bolmer S. Thompson , Dzieciuch Matthew A. , Worcester Peter F. , Andrew Rex K. , Buck Linda J. , Mercer James A. , Colosi John A. , Howe Bruce M.
Published: July 2009

Receptions, from a ship-suspended source (in the band 50–100Hz) to an ocean bottom seismometer (about 5000m depth) and the deepest element on a vertical hydrophone array (about 750m above the seafloor) that were acquired on the 2004 Long-Range Ocean Acoustic Propagation Experiment in the North Pacific Ocean, are described. The ranges varied from 50to3200km. In addition to predicted ocean acoustic arrivals and deep shadow zone arrivals (leaking below turning points), “deep seafloor arrivals,” that are dominant on the seafloor geophone but are absent or very weak on the hydrophone array, are observed. These deep seafloor arrivals are an unexplained set of arrivals in ocean acoustics possibly associated with seafloor interface waves.
Effects of envelope bandwidth on the intelligibility of sine- and noise-vocoded speech
Authors: Souza Pamela , Rosen Stuart
Published: July 2009

The choice of processing parameters for vocoded signals may have an important effect on the availability of various auditory features. Experiment 1 varied envelope cutoff frequency (30 and 300 Hz), carrier type (sine and noise), and number of bands (2–5) for vocoded speech presented to normal-hearing listeners. Performance was better with a high cutoff for sine-vocoding, with no effect of cutoff for noise-vocoding. With a low cutoff, performance was better for noise-vocoding than for sine-vocoding. With a high cutoff, performance was better for sine-vocoding. Experiment 2 measured perceptibility of cues to voice pitch variations. A noise carrier combined with a high cutoff allowed intonation to be perceived to some degree but performance was best in high-cutoff sine conditions. A low cutoff led to poorest performance, regardless of carrier. Experiment 3 tested the relative contributions of comodulation across bands and spectral density to improved performance with a sine carrier and high cutoff. Comodulation across bands had no effect so it appears that sidebands providing a denser spectrum improved performance. These results indicate that carrier type in combination with envelope cutoff can alter the available cues in vocoded speech, factors which must be considered in interpreting results with vocoded signals.
Distortion-product otoacoustic emission input/output characteristics in normal-hearing and hearing-impaired human ears
Authors: Neely Stephen T. , Johnson Tiffany A. , Kopun Judy , Dierking Darcia M. , Gorga Michael P.
Published: July 2009

Distortion-product otoacoustic emission (DPOAE) input/output (I/O) functions were measured in 322 ears of 176 subjects at as many as 8 f2 frequencies per ear for a total of 1779 I/O functions. The f2 frequencies ranged from 0.7 to 8 kHz in half-octave steps. Behavioral thresholds (BTs) at the f2 frequencies ranged from −5 to 60 dB hearing loss (HL). Both linear-pressure and nonlinear, two-slope functions were fitted to the data. The two-slope function describes I/O compression as output-controlled self-suppression. Most I/O functions (96%) were better fitted by the two-slope method. DPOAE thresholds based on each method were used to predict BTs. Compared to estimates based on linear-pressure functions, individual BTs predicted from DPOAE thresholds based on the two-slope model had lower residual error and accounted for more variance. Another advantage of the two-slope method is that it provides an estimate of response growth rate (RGR) that is not tied to threshold. At all frequencies, the median low-level RGR (across I/O functions of the same f2 and BT) usually increased as BT increased, while high-level compression decreased. The observed characteristics of DPOAE I/O functions are consistent with the loss of cochlear compression that is typically associated with mild-to-moderate HL.
Blind location and separation of callers in a natural chorus using a microphone array
Authors: Jones Douglas L. , Ratnam Rama
Published: July 2009

Male frogs and toads call in dense choruses to attract females. Determining the vocal interactions and spatial distribution of the callers is important for understanding acoustic communication in such assemblies. It has so far proved difficult to simultaneously locate and recover the vocalizations of individual callers. Here a microphone-array technique is developed for blindly locating callers using arrival-time delays at the microphones, estimating their steering-vectors, and recovering the calls with a frequency-domain adaptive beamformer. The technique exploits the time-frequency sparseness of the signal space to recover sources even when there are more sources than sensors. The method is tested with data collected from a natural chorus of Gulf Coast toads (Bufo valliceps) and Northern cricket frogs (Acris crepitans). A spatial map of locations accurate to within a few centimeters is constructed, and the individual call waveforms are recovered for nine individual animals within a 9×9m2. These methods work well in low reverberation when there are no reflectors other than the ground. They will require modifications to incorporate multi-path propagation, particularly for the estimation of time-delays.
Numerical and experimental simulation of the effect of long bone fracture healing stages on ultrasound transmission across an idealized fracture
Authors: Gheduzzi S. , Dodd S. P. , Miles A. W. , Humphrey V. F. , Cunningham J. L.
Published: July 2009

The effect of various stages of fracture healing on the amplitude of 200 kHz ultrasonic waves propagating along cortical bone plates and across an idealized fracture has been modeled numerically and experimentally. A simple, water-filled, transverse fracture was used to simulate the inflammatory stage. Next, a symmetric external callus was added to represent the repair stage, while a callus of reducing size was used to simulate the remodeling stage. The variation in the first arrival signal amplitude across the fracture site was calculated and compared with data for an intact plate in order to calculate the fracture transmission loss (FTL) in decibels. The inclusion of the callus reduced the fracture loss. The most significant changes were calculated to occur from the initial inflammatory phase to the formation of a callus (with the FTL reducing from 6.3 to between 5.5 and 3.5 dB, depending on the properties of the callus) and in the remodeling phase where, after a 50% reduction in the size of the callus, the FTL reduced to between 2.0 and 1.3 dB. Qualitatively, the experimental results follow the model predictions. The change in signal amplitude with callus geometry and elastic properties could potentially be used to monitor the healing process.
High-frequency acoustic communications achieving high bandwidth efficiency
Authors: Song H. C. , Hodgkiss W. S. , Kuperman W. A. , Akal T. , Stevenson M.
Published: July 2009

A recent communications experiment was conducted in a shallow water environment at high-frequency permitting the use of a large bandwidth (11–19kHz). This paper investigates the communication performance versus various symbol rates (or bandwidths) in terms of output signal-to-noise ratio with an assortment of constellations, illustrating a trade-off between performance and data rate. A high bandwidth efficiency of 4bits∕sHz is demonstrated using 32 quadrature amplitude modulation with a data rate of 31.25kbits∕s over a 2.2-km range.
Perceptually relevant parameters for virtual listening simulation of small room acoustics
Authors: Zahorik Pavel
Published: July 2009

Various physical aspects of room-acoustic simulation techniques have been extensively studied and refined, yet the perceptual attributes of the simulations have received relatively little attention. Here a method of evaluating the perceptual similarity between rooms is described and tested using 15 small-room simulations based on binaural room impulse responses (BRIRs) either measured from a real room or estimated using simple geometrical acoustic modeling techniques. Room size and surface absorption properties were varied, along with aspects of the virtual simulation including the use of individualized head-related transfer function (HRTF) measurements for spatial rendering. Although differences between BRIRs were evident in a variety of physical parameters, a multidimensional scaling analysis revealed that when at-the-ear signal levels were held constant, the rooms differed along just two perceptual dimensions: one related to reverberation time (T60) and one related to interaural coherence (IACC). Modeled rooms were found to differ from measured rooms in this perceptual space, but the differences were relatively small and should be easily correctable through adjustment of T60 and IACC in the model outputs. Results further suggest that spatial rendering using individualized HRTFs offers little benefit over nonindividualized HRTF rendering for room simulation applications where source direction is fixed.
Limiting unwanted cues via random rove applied to the yes-no and multiple-alternative forced choice paradigms
Authors: Dai Huanping , Kidd Gerald
Published: July 2009

When a random rove is used in a perceptual task to control the influence of an unwanted cue that may confound the decision strategy of primary interest, the effectiveness of the rove is determined by its range. Green [Profile Analysis (Oxford University Press, Oxford, 1988)] provided a formula which allows experimenters to determine the roving range required to ensure that the listeners relying on the unwanted cue cannot exceed a pre-defined percentage of correct responses in a two-interval, two-alternative forced-choice experiment. Here, Green’s analysis is extended to the yes-no and m-alternative, forced-choice paradigms (m>2).
Efficacy of High Doses of Daptomycin versus Alternative Therapies against Experimental Foreign-Body Infection by Methicillin-Resistant
Staphylococcus aureus
Authors: Murillo O. , Garrigós C. , Pachón M. E. , Euba G. , Verdaguer R. , Cabellos C. , Cabo J. , Gudiol F. , Ariza J.
Published: July 2009

Since the currently approved dose of daptomycin (6 mg/kg of body weight/day) has been associated with clinical failures and resistance development, higher doses for some difficult-to-treat infections are being proposed. We studied the efficacy of daptomycin at high doses (equivalent to 10 mg/kg/day in humans) and compared it to that of reference and alternative treatments in a model of foreign-body infection with methicillin (meticillin)-resistant
Staphylococcus aureus.
In vitro studies were conducted with bacteria in the log and stationary phases. For the in vivo model, therapy with daptomycin at 100 mg/kg/day, vancomycin at 50 mg/kg/12 h, rifampin (rifampicin) at 25 mg/kg/12 h, or linezolid at 35 mg/kg/12 h was administered for 7 days. Antibiotic efficacy was evaluated using either bacteria from tissue cage fluids or those attached to coverslips. We screened for the emergence of linezolid- and rifampin-resistant strains and analyzed the surviving population from the daptomycin-treated group. Only daptomycin was bactericidal in both the log- and stationary-phase studies. Daptomycin (decrease in the log number of CFU per milliliter of tissue cage fluid, 2.57) and rifampin (decrease, 2.6 log CFU/ml) were better (
P
< 0.05) than vancomycin (decrease, 1.1 log CFU/ml) and linezolid (decrease, 0.9 log CFU/ml) in the animal model. Rifampin-resistant strains appeared in 60% of cases, whereas no linezolid resistance emerged. No daptomycin-resistant subpopulations were detected at frequencies of 10
−7
or higher. In conclusion, daptomycin at high doses proved to be as effective as rifampin, and the two were the most active therapies for this experimental foreign-body infection. These high doses ensured a profile of safety from the development of resistance.
Artemisone and Artemiside Control Acute and Reactivated Toxoplasmosis in a Murine Model
Authors: Dunay Ildiko R. , Chan Wing Chi , Haynes Richard K. , Sibley L. David
Published: July 2009

Immunocompromised patients are at risk of developing toxoplasmosis, and although chemotherapy is available, standard treatments are often complicated by severe side effects. Artemisinin is a new highly potent antimalarial drug that has activity againstToxoplasma gondiiin vitro. However, artemisinin derivatives have previously been ineffective in vivo using a rat model of toxoplasmosis. In the present study, the efficacy of several new artemisinin derivates was investigated for treatment of mice infected with the parasiteToxoplasma gondii. Artemiside and artemisone displayed better inhibition than either artemisinin or artesunate against the parasite in vitro. Artemiside and artemisone treatment controlled parasite replication in vivo, and mice survived the acute infection. In a murine model of reactivated toxoplasmosis, both drugs increased survival, although artemiside was more effective. These results indicate that these newer derivatives of artemisinin may have potential for treatment of toxoplasmosis.
Efficacy of Albaconazole against
Candida albicans
in a Vaginitis Model
Authors: González Gloria M. , Robledo Efrén , Garza-González Elvira , Elizondo Mariana , González J. Gerardo
Published: July 2009

The efficacy of albaconazole (ABC) was evaluated using a murine model of vaginal
Candida albicans
infection. Both ABC and fluconazole (FLC) were effective in reducing the fungal load from vaginas of infected mice; however, ABC demonstrated encouraging activities against an FLC-resistant strain, with trends toward superiority over FLC in some treatment groups.
Involvement of
pmrAB
and
phoPQ
in Polymyxin B Adaptation and Inducible Resistance in Non-Cystic Fibrosis Clinical Isolates of
Pseudomonas aeruginosa
Authors: Schurek Kristen N. , Sampaio Jorge L. M. , Kiffer Carlos R. V. , Sinto Sumiko , Mendes Caio M. F. , Hancock Robert E. W.
Published: July 2009

During investigation of susceptibility testing methods for polymyxins, 24 multidrug-resistant clinical isolates of
Pseudomonas aeruginosa
were observed to have a distinct, reproducible phenotype in which skipped wells were observed during broth microdilution testing for polymyxin B. Possible mechanisms underlying this phenotype were investigated. The effects of various concentrations of polymyxin B on growth, the expression of resistance genes, and outer-membrane permeability were observed. Real-time PCR was performed to compare the expression, in response to selected concentrations of polymyxin B, of genes related to the PhoP-PhoQ and PmrA-PmrB two-component regulatory systems in polymyxin B-susceptible isolate PAO1, polymyxin B-resistant isolate 9BR, and two isolates (19BR and 213BR) exhibiting the skipped-well phenotype. 19BR and 213BR appeared to have similar basal levels of expression compared to that of PAO1 for
phoQ
,
arnB
, and PA4773 (from the
pmrAB
operon), and in contrast, 9BR had 52- and 280-fold higher expression of
arnB
and PA4773, respectively. The expression of
arnB
and PA4773 increased in response to polymyxin B in a concentration-dependent manner for 9BR but not for 19BR and 213BR. For these isolates, expression was significantly increased for
arnB
and PA4773, as well as
phoQ
, only upon exposure to 2 μg/ml polymyxin B but not at a lower concentration of 0.125 μg/ml. The sequencing of the
pmrAB
and
phoPQ
operons for all three isolates revealed a number of unique mutations compared to that for PAO1. 1-
N
-phenylnaphthylamine (NPN) was used to study the effect of preincubation with polymyxin B on the self-promoted uptake of polymyxin B across the outer membrane. The preincubation of cells with 2 μg/ml polymyxin B affected baseline membrane permeability in 19BR and 213BR and also resulted in a reduced rate of NPN uptake in these isolates and in PAO1 but not in 9BR. The results presented here suggest that the skipped-well isolates have the ability to adapt to specific concentrations of polymyxin B, inducing known polymyxin B resistance genes involved in generating alterations in the outer membrane.
Interactions of Enteropathogenic
Escherichia coli
with Pediatric and Adult Intestinal Biopsy Specimens during Early Adherence
Authors: Humphries Romney M. , Waterhouse Christopher C. M. , Mulvey George , Beck Paul , Armstrong Glen D.
Published: July 2009

Enteropathogenic
Escherichia coli
(EPEC) strains cause watery diarrhea almost exclusively in young children. The basis for this age discrimination has never been determined, but it may be related to host cell receptors. During infection, EPEC strains express type IV bundle-forming pili composed of repeating subunits of the protein called bundlin. The very first interaction between EPEC and in vitro-cultured epithelial cells is mediated by the binding of α-bundlin to a carbohydrate receptor that contains, at a minimum, the
N
-acetyllactosamine (LacNAc) glycan sequence. However, bundlins expressed from the β-bundlin allele do not bind LacNAc glycan sequences. Herein, we investigated whether EPEC strains use α-bundlin to mediate early adherence to human intestinal biopsy specimens cultured in vitro by assessing the ability of isogenic EPEC mutants expressing either the α
1
- or β
1
-bundlin allele or a bundlin-deficient EPEC strain to bind to these specimens. Furthermore, we directly compared the abilities of a wild-type EPEC strain to bind to the epithelial surfaces of both human adult and pediatric biopsy specimens. Our results demonstrate that β-bundlin does not act as an adhesin during early EPEC adherence to adult duodenal biopsy specimens. The results also indicate that EPEC binds equally well to adult and pediatric biopsy specimens in an early adherence assay. This result is supported by the finding that the early adherence of EPEC to both adult and pediatric biopsy specimens was inhibited by LacNAc neoglycoconjugates, suggesting that organisms expressing α-bundlin-type bundle-forming pili initially bind to related glycan receptors in both age groups.