Average Void Volume Research Articles

Uroflowmetry: nomograms in healthy young Pakistani men.

To create a nomogram based on urine volume and flow of males without lower urinary tract symptoms. The prospective, cross-sectional study was conducted at the Department of Urological Surgery and Transplantation, Jinnah Postgraduate Medical Centre, Karachi, from November 1, 2020, to October 31, 2022, and comprised healthy young males without lower urinary tract dysfunction who were recruited from the hospital as well as a large textile mill. They were asked to void on their normal desire. Uroflowmetry was done to determine maximum flow rate, average flow rate, and void volume values. A best-fit regression model was used to formulate uroflowmetry nomogram using average and maximum urine flow rate over voided volume. The sample size was calculated using PASS 2020 Power Analysis and Sample Size Software (2020). NCSS, LLC. Kaysville, Utah, USA. The database was developed on NCSS 2020 Statistical Software (2020). NCSS, LLC. Kaysville, Utah, USA for the data analysis. Of the 468 male subjects enrolled, data was analysed related to 432(92.3%). The mean age was 25.59±4.32 years. Mean maximum flow rate, average flow rate and void volume were 25.28±8.70mL/s, 14.77±4.79mL/s and 405.48±163.86mL, respectively. The association of age was noted with maximum flow rate (r=0.1435, p=0.004), average flow rate (r=0.1135, p=0.004) and void volume (r=0.0619, p=0.004). The best-fitted model for maximum and average flow rate was subsequently developed which was statistically significant (p<0.05). The nomograms developed could reliably predict the maximal flow rate in young Pakistani men.

Systematic Evaluation of Adhesion and Fracture Toughness in Multi-Material Fused Deposition Material Extrusion.

Material extrusion (MEX) additive manufacturing has successfully fabricated assembly-free structures composed of different materials processed in the same manufacturing cycle. Materials with different mechanical properties can be employed for the fabrication of bio-inspired structures (i.e., stiff materials connected to soft materials), which are appealing for many fields, such as bio-medical and soft robotics. In the present paper, process parameters and 3D printing strategies are presented to improve the interfacial adhesion between carbon fiber-reinforced nylon (CFPA) and thermoplastic polyurethane (TPU), which are extruded in the same manufacturing cycle using a multi-material MEX setup. To achieve our goal, a double cantilever beam (DCB) test was used to evaluate the mode I fracture toughness. The results show that the application of a heating gun (assembled near the nozzle) provides a statistically significant increase in mean fracture toughness energy from 12.3 kJ/m2 to 33.4 kJ/m2. The underlying mechanism driving this finding was further investigated by quantifying porosity at the multi-material interface using an X-ray computed tomography (CT) system, in addition to quantifying thermal history. The results show that using both bead ironing and the hot air gun during the printing process leads to a reduction of 24% in the average void volume fraction. The findings from the DCB test and X-ray CT analysis agree well with the polymer healing theory, in which an increased thermal history led to an increased fracture toughness at the multi-material interface. Moreover, this study considers the thermal history of each printed layer to correlate the measured debonding energy with results obtained using the reptation theory.

Clinical efficacy and safety analysis of type A botulinum toxin in the treatment of adolescents with refractory overactive bladder.

The objective of this study was to assess the clinical effectiveness and safety of type A botulinum toxin in the treatment of refractory overactive bladder in adolescents. We conducted a retrospective analysis of 37 adolescent patients with refractory overactive bladder who were treated at the Urology Department of Hangzhou Third People's Hospital between January 2018 and August 2023. These patients received intravesical injections of type A botulinum toxin at a concentration of 10 U/mL, with an average of 20 injection points. We recorded changes in urination diaries and urodynamic parameters both before and 1 month after treatment. After 1 month of treatment, significant improvements were observed in several parameters, when compared to the pretreatment values. These included daytime frequency of urination (11.13 ± 6.45), average single void volume (173.24 ± 36.48) mL, nighttime frequency of urination (2.43 ± 0.31), urgency episodes (3.12 ± 0.27), initial bladder capacity (149.82 ± 41.34) mL, and maximum bladder capacity (340.25 ± 57.12) mL (all P < .001). After the first treatment, 5 patients had mild hematuria, 4 patients had urinary tract infection, and 1 patient had urinary retention, which was relieved after catheterization. No serious complications or adverse reactions were observed in other patients. The follow-up period ranged from 6 to 18 months, and the duration of efficacy varied from 2 to 8 months. Eight patients who initially had treatment failure achieved symptom relief after reinjection. In adolescents with refractory overactive bladder who do not respond well to conventional drug therapy, type A botulinum toxin can be administered safely and effectively. It significantly improves lower urinary tract symptoms and enhances the quality of life for these patients.

Urinary Bladder Dysfunction in a Novel Model of Neuroendocrine Stress

Chronic stress can lead to urinary bladder dysfunction and pain either through actions within the central nervous system or by mechanisms that are locally induced in the bladder. Prolonged upregulation of brain-derived neurotrophic factor (BDNF) in the paraventricular nucleus of the hypothalamus (PVN) has been shown to induce hypertension and chronically elevate activities of the sympathetic nervous system and hypothalamus-pituitary-adrenal axis. Taking advantage of this mechanism, we created a novel model of chronic neuroendocrine stress by subjecting male Sprague Dawley rats to bilateral PVN injections of AAV2 viral vectors expressing either BDNF or GFP (for control). We tested the hypothesis that model-induced chronic neuroendocrine stress would impair bladder function. Bladder activity was assessed 10 weeks post-injections by monitoring the number of urinary voids and average urinary void volume along with water intake over a 48-hour period. To further characterize changes in the urinary bladder, bladder weights were recorded, and in vitro bladder strip experiments were conducted 14 weeks after viral vector injections. BDNF overexpression in the hypothalamus led to significantly lower daily urine output even though water intake remained unaffected, suggesting that BDNF-treated animals showed a significantly higher non-urine-related fluid compared to GFP controls (daily urine output = GFP: 33.85±4.94, BDNF: 14.82±2.18, p &lt; 0.01. Interestingly, despite a lower total daily urine volume, BDNF-treated animals had a significantly higher number of urinary voids (GFP: 7.50±1.42, BDNF: 15.38±2.76; GFP vs. BDNF: p &lt; 0.001) and lower average void volume (GFP: 1.19±0.15, BDNF: 0.27±0.07; GFP vs. BDNF: p &lt; 0.01), thus emulating the overactive bladder phenotype, a common complication in humans with chronic stress. These findings were complemented by in vitro experiments where bladder strips from BDNF rats showed significantly higher contractility as tested with high K+ concentration and electric field stimulation. Moreover, Carbachol-induced stimulation of muscarinic receptors in BDNF bladder strips also trended towards higher contractility. However, urinary bladder weights were unaffected by BDNF overexpression. In summary, we demonstrated that prolonged hypothalamic BDNF overexpression, a model of chronic neuroendocrine stress, leads to significant alterations in bladder function such that BDNF-treated rats exhibited a higher number of urinary voids and lower average void volume compared to GFP controls, and bladder strip experiments suggest that enhanced smooth muscle contractility may contribute to this overactive bladder phenotype. These findings from our novel experimental model will help elucidate pathways through which neuroendocrine stress mechanisms contribute to the development of the overactive bladder syndrome. Funded by R01HL166464, R03AG072016 and R01DK125543. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Towards an accurate method for column void volume determination using liquid chromatography-mass spectrometry

Prediction of analyte retention times requires prior knowledge of the column void volume, the measurement of which is still highly contested within the literature and therefore experimental based prediction is often used. In this study, we investigated deuterated acetonitrile as an isotopically labelled mobile phase component to observe its elution behaviour in a binary mixture with water at 25 different mobile phase compositions (from 5 to 95 vol.% of acetonitrile), on two stationary phases (C8 and C18), and at two temperatures (30 and 40 °C) using LC-MS. The same experimental design was additionally used for three commonly used neutral void volume markers: uracil, phloroglucinol and N,N-dimethylformamide. Temperature was observed to influence the elution of acetonitrile in an inversely proportional manner with higher temperatures coinciding with lower elution times. By utilizing a three-way ANOVA, the composition of the mobile phase has been shown to have a significant effect on deuterated acetonitrile and other investigated void volume markers, demonstrating the fact that both void volume markers and acetonitrile itself exhibit retention-like behaviour. Excess adsorption isotherms for acetonitrile were calculated using deuterated acetonitrile elution data. The comparison of void volumes, obtained with conventional neutral void volume markers, revealed the former to be 24–36% lower than the void volume obtained using deuterated acetonitrile, as an isotopically labelled mobile phase component. For a water:acetonitrile mobile phase, the minor disturbance method using deuterated acetonitrile to obtain an integral average void volume (2.08 and 2.05 mL for C18 at 30 and 40 °C, respectively and 2.16 and 2.13 mL for C8 at 30 and 40 °C, respectively) was found to be the most appropriate method for determining the elusive column void volume.

The influence of the surface roughness, creep and relaxation on the performance of elastomeric liners for sustainable glass bottle closures

Glass bottles having a metal closure are preferred for oxygen sensitive beverages e.g. beer. Using thinner closure which comprise polyvinyl chloride-free component is more sustainable. However, protecting the sealing performance as a result of metal closure thickness reduction is challenging. Here we show the relation between the leakage in beer bottles and surface roughness of three different thermoplastic elastomer seals. Compression relaxation and creep-recovery behavior of seals have been analyzed by using a dynamic mechanical analyzer. The results showed that metal downsizing was possible with Liner A (low density polyethylene (LDPE)/styrene-ethylene-butylene-styrene) and B (LDPE/ styrene-butadiene-styrene), but not with Liner C (high-density polyethylene/butyl rubber). Optimizing smaller surface topography parameters such as the surface roughness depth Rz, kurtosis Sku, average void volume Vvv, arithmetic mean peak curvature Spc, the density of surface peaks Spd and higher peak material volume Vmp, peak material portion Smr resulted in a better sealing performance. Liner C was found to show an increased leakage risk, since there was a high level of stress relaxation leading to a reduced sealing force. The sealing liner material with low relaxation, low elastic modulus and high creep recovery compliance was found to ensure better sealing when thinner metal closures are used.

Fracture Areas Quantitative Investigating of Bending-Torsion Fatigued Low-Alloy High-Strength Steel

In this study, the impact of pseudo-random non-proportional bending-torsion fatigue loadings proportion on the fatigue life and the fracture surface topography was analyzed. Investigation was carried out for 24 specimens made of S355J2 steel with 11 different ratios of maximum stresses λ. For these cases, after the fatigue tests, the surface topography measurements were carried out using an optical profilometer, using the focus variation method. Three fracture zones were analyzed for each specimen: (1) total; (2) propagation; (3) rupture, taking into account the root average square height Sq and void volume Vv parameters. The results pointed that ratio of maximum stresses λ is the most influenced on volume surface parameters represented by void volume at a given height Vv, in the rupture area. A new fatigue loading parameter P was used, depending on fatigue life T and ratio of maximum stresses λ, which shows very good correlation in 4th degree type of fit, to void volume Vv parameter for the rupture area.

A greyscale volumetric lattice Boltzmann method for upscaling pore-scale two-phase flow

Solving image-based pore-scale flow and transport in porous materials is a mainstream of fundamental and industrial research to reveal the pertinent physics in the field of hydrogeology, reservoir engineering, paper and filter engineering. This research discipline requires tremendous integration of multidisciplinary research areas of image processing, computational fluid modelling, and high-performance computing. The key challenge in pore-scale multi-phase flow simulation is the overwhelming computational expense. In this paper, we develop a new computational method that integrates GPU-accelerated volumetric lattice Boltzmann method (VLBM) with an upscaling scheme to solve the pore-scale two-phase flow at the centimetre-level length scales. The lattice Boltzmann concept is employed to solve both the level-set equation for image segmentation and governing equations for multi-phase flow dynamics. The signed distance field solved from the level set equation is used to calculate the void volume ratio of each lattice cell, resulting in a seamless connection between image segmentation and computational fluid dynamics. The pore-scale porous materials upscaling is carried out through the average void volume ratio of the neighbouring cells. The algorithm is rigorously tested in three cases: contact angle test for droplets between two plates, co-current flow in a cylindrical tube, and the two-phase flow in a sandstone sample. For the sandstone sample, the porosity, void space topology, relative permeability and preferential flow channels are well retained after 8-times upscaling, while the computational time is dramatically decreased.

High-definition ultrasound characterization of acute cyclophosphamide-induced cystitis in the mouse.

PurposeTo examine associations if any between changes in voiding function, hematuria, and bladder ultrasonography metrics in murine cyclophosphamide-induced chemical cystitis.Materials and MethodsCystitis was induced in 6 female mice by an intraperitoneal injection of cyclophosphamide (300 mg/kg). Voiding frequency, void volume, hematuria assessment, and ultrasonographic measurements of the bladder were obtained at baseline, days 1 to 5, and days 9, 11, and 13. Voiding was induced with preferred sweet drinking solution and voiding data collected using an automated data collection system in 135 minute sessions. Bladder wall thickness, lumen volume, and vascular Doppler were acquired using a high definition ultrasound system. Spearman's correlation was used to analyze the association between the voiding changes, hematuria, and ultrasound findings.ResultsHematuria was present 24 hours after cyclophosphamide injection. All animals displayed increased bladder vascularity, bladder wall thickness, and void frequency that was associated with concurrent decreased total and average void volumes. Increased bladder wall vascularity was correlated with the presence of hematuria (r=0.59, p<0.01) and bladder wall thickness (r=0.79, p<0.01). Hematuria correlated with increased void frequency (r=0.34, p<0.01). Average void volume was negatively correlated with hematuria (r=−0.50, p<0.01) and frequency (r=−0.38, p<0.01).ConclusionsHigh-definition ultrasound imaging permits in vivo monitoring of changes in bladder morphology associated with voiding function in relation to cyclophosphamide-induced cystitis. Ultrasound imaging of the bladder may assist in differential diagnosis of bladder dysfunction.

Effect of Surface Topography Parameters on Friction and Wear of Random Rough Surface.

In order to explore the relationship between the surface topography parameters and friction properties of a rough contact interface under fluid dynamic pressure lubrication conditions, friction experiments were carried out. The three-dimensional surface topography of specimens was measured and characterized with a profile microscopy measuring system and scanning electron microscope. The friction coefficient showed a trend of decreasing first and then increasing with the increase in some surface topography parameters at lower pressure, such as the surface height arithmetic mean Sa, surface height distribution kurtosis Sku, surface volume average volume Vvv, and surface center area average void volume Vvc, which are the ISO 25178 international standard parameters. The effects of surface topographic parameters on friction were analyzed and the wear mechanism of the worn surface was presented. The wear characteristics of the samples were mainly characterized as strain fatigue, grinding, and scraping. The results provide a theoretical basis for the functional characterization of surface topography.

Quantitative X-Ray Microcomputed Tomography Assessment of Internal Tablet Defects

Physical tablet defects are related to internal structural defects that are not easily assessed by the traditional methods, such as dusting, laminating, or fracturing during appearance, friability, or hardness testing. Also, these methods do not allow objective and quantitative investigation of the role of formulation and process variables, which is essential for quality-by-design drug product development. In this study, an X-ray microcomputed tomography (XμCT) method to analyze internal tablet defects is developed using tablets from a quality-by-design design-of-experiment study. The design of experiment investigated the effect of roller compaction roll force, filler composition, and the amount of magnesium stearate on tablet quality attributes. Average contiguous void volume by optical image processing and fracture size distribution and direction by artificial intelligence–based image processing quantified the internal tablet fracture severity. XμCT increased formulation and process knowledge in support of scale-up manufacturing. We demonstrated how XμCT can be incorporated as a part of a holistic approach to quantitatively identify and mechanistically assess the risks of internal tablet defects. Furthermore, expanding the use of XμCT with an artificial intelligence–based quantitative analysis can deepen our tableting knowledge from an empirical understanding to a mechanistic understanding of compaction phenomenon.

Damage Progression and Fragmentation in Atomistic, Single Crystal Copper at High Strain Rates

We show a correlation between nanoscale damage and fragmentation length scale through atomistic simulations. We simulated homogeneously expanding perfect, single crystal copper at rates ranging from 1E+08 to 3E+10 s-1 and temperatures from 200 to 1000 K. Damage was quantified in terms of void number density, average void volume, and void volume fraction. We quantified fragmentation size in terms of a length scale parameter, the solid volume per void surface area. A-1⁄2 power law relationship between the fragment length scale and strain rate was observed following the predictions of Mott. The fragmentation length scale and the maximum void number density are strongly correlated for this damage mechanism. We can scale up the relationships between damage and fragmentation observed in the molecular dynamics simulations to motivate a continuum scale fragmentation model.

Focused Ion Beam Tomography Reveals the Presence of Micro-, Meso-, and Macroporous Intracrystalline Regions Introduced into Calcite Crystals by the Gastropod Nacre Protein AP7

Intracrystalline modification of calcium carbonates by macromolecules is a fascinating process that offers insights into potential pathways for modifying the material properties of inorganic solids. Recently, we reported on the induction of intracrystalline nanoporosities within calcite by the nacre layer intracrystalline protein, AP7 (Haliotis rufescens). In this report we revisited this AP7-mediated phenomenon and tracked time-dependent intracrystalline porosity formation during in vitro mineralization using FIB/SEM serial milling. We find that AP7 induces intracrystalline nanoporosities as early as 1 min of elapsed assay time. Quantitation of pore regions confirms that average cross-sectional volume (ACSV), average void volume (AVV), and percent porosity parameters increase over time, leading to the formation of porous calcite crystals with a high surface-to-volume ratio. FIB serial milling, SEM imaging, and 3-D tomography revealed the presence of unexpected semicontinuous channels and cavities in the subsurface regions of a representative 60 min assay crystal. The random locations of these intracrystalline features are limited to the top and sides of the calcite crystal, which correspond to the sites of AP7 protein phase deposition during mineral formation. This random porosity distribution was also documented for protein-containing voids within nacre aragonite tablets in situ. In some instances we observed geometric relationships between adjacent channels and cavities. Interestingly, all three IUPAC-defined material porosity categories (micro-, meso-, and macro-) were represented in the AP7-treated crystals. Thus, the deposition of AP7 protein phases onto calcite surfaces induces surface nanoparticle nucleation and subsurface multiscale intracrystalline porosities and interconnected channels.

NanoXCT: a novel technique to probe the internal architecture of pharmaceutical particles.

To demonstrate the novel application of nano X-ray computed tomography (NanoXCT) for visualizing and quantifying the internal structures of pharmaceutical particles. An Xradia NanoXCT-100, which produces ultra high-resolution and non-destructive imaging that can be reconstructed in three-dimensions (3D), was used to characterize several pharmaceutical particles. Depending on the particle size of the sample, NanoXCT was operated in Zernike Phase Contrast (ZPC) mode using either: 1) large field of view (LFOV), which has a two-dimensional (2D) spatial resolution of 172 nm; or 2) high resolution (HRES) that has a resolution of 43.7 nm. Various pharmaceutical particles with different physicochemical properties were investigated, including raw (2-hydroxypropyl)-beta-cyclodextrin (HβCD), poly (lactic-co-glycolic) acid (PLGA) microparticles, and spray-dried particles that included smooth and nanomatrix bovine serum albumin (BSA), lipid-based carriers, and mannitol. Both raw HβCD and PLGA microparticles had a network of voids, whereas spray-dried smooth BSA and mannitol generally had a single void. Lipid-based carriers and nanomatrix BSA particles resulted in low quality images due to high noise-to-signal ratio. The quantitative capabilities of NanoXCT were also demonstrated where spray-dried mannitol was found to have an average void volume of 0.117 ± 0.247 μm(3) and average void-to-material percentage of 3.5%. The single PLGA particle had values of 1993 μm(3) and 59.3%, respectively. This study reports the first series of non-destructive 3D visualizations of inhalable pharmaceutical particles. Overall, NanoXCT presents a powerful tool to dissect and observe the interior of pharmaceutical particles, including those of a respirable size.

565 PHASE 3 EFFICACY AND SAFETY OF ONCE-MONTHLY OXYBUTYNIN VAGINAL RING DELIVERING 4 MG/DAY OR 6 MG/DAY VS PLACEBO RING IN WOMEN WITH URGE INCONTINENCE, FREQUENCY, AND URGENCY SYMPTOMS OF OVERACTIVE BLADDER

You have accessJournal of UrologyUrodynmaics/Incontinence/Female Urology: Incontinence, Evaluation & Therapy (I)1 Apr 2013565 PHASE 3 EFFICACY AND SAFETY OF ONCE-MONTHLY OXYBUTYNIN VAGINAL RING DELIVERING 4 MG/DAY OR 6 MG/DAY VS PLACEBO RING IN WOMEN WITH URGE INCONTINENCE, FREQUENCY, AND URGENCY SYMPTOMS OF OVERACTIVE BLADDER Mark Swierzewski, Larry Seidman, Sue Dasen, and Herman Weiss Mark SwierzewskiMark Swierzewski Tampa, FL More articles by this author , Larry SeidmanLarry Seidman Philadelphia, PA More articles by this author , Sue DasenSue Dasen Frazer, PA More articles by this author , and Herman WeissHerman Weiss Petach Tikva, Israel More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.1961AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Oxybutynin vaginal ring (OxyVR) is a novel delivery system developed to bypass hepatic metabolism and improve tolerability over oral antimuscarinic agents used to treat overactive bladder (OAB). Our objective was to compare the efficacy and safety of OxyVR delivering 4 or 6 mg/day to placebo vaginal ring (PVR) in women with precisely defined OAB symptoms. METHODS In this randomized, double-blind, multicenter, 12-week (W) trial (NCT00685113), women with pure/predominantly urge incontinence were consented and randomized to OxyVR4, OxyVR6 or PVR. A new vaginal ring (VR) was inserted every 4W. Women whose 3-day screening diaries met all 3 OAB-defining criteria comprised the analysis population: ≥5 urge incontinence episodes (IEs)/W; average daily urinary frequency (UFreq) ≥8 voids/24h; average void volume (VV) ≤3L/24h. Women inserting ≥1VR were evaluated for safety. Efficacy was assessed by comparing changes from baseline in total (stress +urge) IEs/W (primary endpoint), UFreq, VV and percent with no IEs in a final 3-day diary. RESULTS A total of 1102 women (362 randomized to OxyVR4, 369 to Oxy VR6, 371 to PVR) comprised the safety population; 882 (295, 278, 309, respectively) met all 3 OAB criteria. Groups had similar baseline demographic and OAB characteristics; 94% completed 12W. From baseline to 12W, OxyVR4 and OxyVR6 treatment resulted in statistically significant improvements compared to PVR in weekly IEs and daily UFreq, with no significant differences in VV (Table 1). In the final 3-day diary, 36% of OxyVR4 (P=0.029), 35% of OxyVR6 (P=0.074) vs 28% of PVR-treated women had no IEs. In the safety population, both OxyVR doses were well tolerated, with no serious adverse events (AEs) attributable to treatment. Dry mouth occurred in 6% (OxyVR4) and 8% (OxyVR6) vs 4% (PVR), constipation in 1%, 1% vs 2%, culture-positive urinary tract infections in 8%, 10% vs 8%, respectively. Few withdrew due to AEs (3.6%, 6.8% vs 3.0%, respectively), only 0.2% for dry mouth. Other vaginal complaints reported in 1.9%-5.9% of women overall were distributed equally across groups. CONCLUSIONS OxyVR offers women a once-monthly, effective, safe, and well tolerated treatment option for OAB. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e232 Peer Review Report Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Mark Swierzewski Tampa, FL More articles by this author Larry Seidman Philadelphia, PA More articles by this author Sue Dasen Frazer, PA More articles by this author Herman Weiss Petach Tikva, Israel More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

A new method of segmentation of compact-appearing, transitional and trabecular compartments and quantification of cortical porosity from high resolution peripheral quantitative computed tomographic images

A transitional or cortico-trabecular junctional zone exists at any location composed of both cortical and trabecular bones such as the metaphyses of tubular bones and short bones like the femoral neck. The transitional zone comprises the inner cortex adjacent to the medullary canal and trabeculae abutting against the cortex contiguous with the endocortical surface. This is a site of vigorous remodeling. Intracortical remodeling cavitates the inner cortex expanding this transitional zone at the price of compact-appearing cortex so that it contains porosity, cortical fragments that resemble trabeculae, and trabeculae abutting the eroding cortex. The porosity of the transitional zone is an important source of bone loss. It reduces bone strength exponentially and is a quantifiable `fingerprint' of structural deterioration.A new automated method of segmentation of bone from background and bone into its compact-appearing cortex, transitional zone, and trabecular compartment is described, with a new approach to quantification of cortical porosity. Segmentation is achieved by automatically selecting attenuation profile curves perpendicular to the periosteal surface. Local bone edges are identified as the beginning and the end of the rising and falling S-shaped portions of the curve enabling the delineation of the compartments. Analyzing ~3600 consecutive overlapping profiles around the perimeter of each cross-sectional slice segments the compartments.Porosity is quantified as the average void volume fraction of all voxels within each compartment. To assess accuracy at the distal radius and tibia, μCT images of cadaveric specimens imaged at 19μm voxel size served as the gold standard. To assess accuracy at the proximal femur, scanning electron microscopy (SEM) images of specimens collected at 2.5μm resolution served as the gold standard.Agreement between HRpQCT and the gold standards for segmentation and quantification of porosity at the distal radius and tibia ranged from R2=0.87 to 0.99, and for the proximal femur ranged from 0.93 to 0.99. The precision error in vivo for segmentation and quantification of porosity in HRpQCT images at the distal radius, given by the root mean square error of the coefficient of variation, ranged from 0.54% for porosity of the transitional zone to 3.98% for area of the compact-appearing cortex.Segmentation of the transitional zone minimizes errors in apportioning cortical fragments and cortical porosity to the medullary compartment and so is likely to allow accurate assessment of fracture risk and the morphological effects of growth, aging, diseases and therapies.

GISAXS and ATR-FTIR Studies on Stress-Induced Microstructure Evolution of a-Si:H under H2 Plasma Exposure

Microstructure evolution in the surface layer of hydrogenated amorphous silicon (a-Si:H) film exposed to H2 plasma is investigated using grazing-incidence small-angle x-ray scattering and attenuated total reflection-Fourier transform infrared spectroscopy. Molecular hydrogen generated in the microvoids through H-abstraction reaction drives the evolution of the void shape from spherical to ellipsoidal as well as increases the average void volume and total void volume fraction. High-pressure H2 in the microvoid promotes the formation of a strained structure with high compressive stress within the a-Si:H film, which favours the generation of the SiHn complex in the subsurface layer of the a-Si:H film by H insertion into strained Si-Si bonds.

Positron annihilation lifetime measurements of mechanically fatigued polystyrene samples

AbstractEarly stages of cyclic fatigue‐loaded polystyrene (PS) specimens were investigated by positron annihilation lifetime spectroscopy (PALS) at a maximum stress amplitude of 15 MPa. PALS yields information about the average unoccupied hole volume. A linear increase in the ortho‐positronium (o‐Ps) lifetime was observed in a range from 0 to 50,000 cycles. This increase occurs homogeneously distributed at different positions along a sample of 170 mm. The average unoccupied void volume increases by 1.2%. On the other hand, the o‐Ps intensity shows no systematic change upon cycling. The results suggest a homogeneous and linear increase in free volume prior to craze formation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1991–1995, 2008

INTRAVESICAL RESINIFERATOXIN FOR THE TREATMENT OF INTERSTITIAL CYSTITIS: A RANDOMIZED, DOUBLE-BLIND, PLACEBO CONTROLLED TRIAL

Interstitial cystitis is a painful bladder condition of unknown etiology and poorly understood pathophysiology. Current therapies have met with limited success. Vanilloid receptor agonists such as resiniferatoxin (RTX) desensitize C-fibers that transmit pain; it is hypothesized that such drugs will be effective in the treatment of interstitial cystitis and painful bladder syndrome by decreasing the pain that leads to urinary frequency and urgency. A randomized, double-blind, placebo controlled study was conducted in 163 patients with interstitial cystitis. Participants were randomly assigned to receive a single intravesical dose of 50 ml of either RTX 0.01 microM, 0.05 microM, 0.10 microM, or placebo. Safety and efficacy was evaluated over 12 weeks. The primary efficacy endpoint was the Global Response Assessment, a 7-point scale rating overall change in symptoms of interstitial cystitis after 4 weeks. Secondary efficacy endpoints included reduction in pain, urgency, frequency, nocturia, average void volume, and the O'Leary-Sant Symptom and Problem Indexes. RTX did not improve overall symptoms, pain, urgency, frequency, nocturia, or average void volume during 12 weeks followup. RTX resulted in a dose-dependent increase in the incidence of instillation pain, but was otherwise generally well tolerated. In the largest prospective, randomized clinical trial reported to date with intravesical vanilloid therapy, single administration of RTX at doses of 0.01 microM to 0.10 microM was not effective in patients with interstitial cystitis.

A NOVEL COMPOSITE SCAFFOLD FOR CARDIAC TISSUE ENGINEERING

One approach to the engineering of functional cardiac tissue for basic studies and potential clinical use involves bioreactor cultivation of dissociated cells on a biomaterial scaffold. Our objective was to develop a scaffold that is (1) highly porous with large interconnected pores (to facilitate mass transport), (2) hydrophilic (to enhance cell attachment), (3) structurally stable (to withstand the shearing forces during bioreactor cultivation), (4) degradable (to provide ultimate biocompatibility of the tissue graft), and (5) elastic (to enable transmission of contractile forces). The scaffold of choice was made as a composite of poly(dl-lactide-co-caprolactone), poly(dl-lactide-co-glycolide) (PLGA), and type I collagen, with open interconnected pores and the average void volume of 80 +/- 5%. Neonatal rat heart cells suspended in Matrigel were seeded into the scaffold at a physiologically high density (1.35 x 10(8) cells/cm(3)) and cultivated for 8 d in cartridges perfused with culture medium or in orbitally mixed dishes (25 rpm); collagen sponge (Ultrafoam) and PLGA sponge served as controls. Construct cellularity, presence of cardiac markers, and contractile properties were markedly improved in composite scaffolds as compared with both controls.