AimsTo critically review studies of the biomechanical properties of connective tissue in the normal and prolapsed human vaginal wall and to identify criteria that are suitable for in vivo measurements which could improve patient management.MethodsThis review covers past and current ex vivo and in vivo instrumentation and analytical methods related to the elastic and viscoelastic properties of vaginal wall connective tissues.ResultsClassical methods, including digital evaluation of the vagina, histological and biomechanical studies of fresh and frozen‐thawed extracts, and biomechanical cadaveric tissue studies have important limitations and have yielded inconsistent results. Newer biomechanical methods may resolve these inconsistencies. One of the more promising is transient, vacuum‐induced tissue expansion and relaxation, via cutometer‐like devices. The technique permits noninvasive observation, applicable to longitudinal studies of patients. In vivo and ex vivo biomechanical methods may better match vaginal wall tissue properties to help with the design of surgical mesh materials, thus improving surgical support and healing.ConclusionMethods have been identified to characterize the in vivo biomechanical behavior of the prolapsing vagina which may serve to advance the care of affected women. Neurourol. Urodynam. 36:499–506, 2017. © 2016 Wiley Periodicals, Inc.

Direct pulp-capping is a method for treating exposed vital pulp with dental material to facilitate the formation of reparative dentin and to maintain vital pulp. Two types of pulp-capping materials, calcium hydroxide and mineral trioxide aggregate, have been most commonly used in clinics, and an adhesive resin has been considered a promising capping material. However, until now, there has been no comprehensive review of these materials. Therefore, in this paper, the composition, working mechanisms and clinical outcome of these types of pulp-capping materials are reviewed.

Wall injury is observed during stent expansion within atherosclerotic arteries, related in part to stimulation of the inflammatory process. Wall stress and strain induced by stent expansion can be closely examined by finite element analysis (FEA), thus shedding light on procedure-induced sources of inflammation. The purpose of this work was to use FEA to examine the interaction of a coiled polymer stent with a plaque-containing arterial wall during stent expansion. An asymmetric fibrotic plaque-containing arterial wall model was created from intravascular ultrasound (IVUS) images of a diseased artery. A 3D model for a coil stent at unexpanded state was generated in SolidWorks. They were imported into ANSYS for FEA of combined stent expansion and fibrotic plaque-distortion. We simulated the stent expansion in the plaqued lumen by increasing balloon pressure from 0 to 12 atm in 1 atm step. At increasing pressure, we examined how the expanding stent exerts forces on the fibrotic plaque and vascular wall components, and how the latter collectively resist and balance the expansive forces from the stent. Results show the expanding coiled stent creates high stresses within the plaque and the surrounding fibrotic capsule. Lower stresses were observed in adjacent medial and adventitial layers. High principal strains were observed in plaque and fibrotic capsule. The results suggest fibrotic capsule rupture might occur at localized regions. The FEA/IVUS method can be adapted for routine examination of the effects of the expansion of selected furled stents against IVUS-reconstructed diseased vessels, to improve stent deployment practices.

We report the influence of body mass index (BMI) on the biomechanical properties of human prolapsed anterior vaginal wall (AVW) tissue samples. We hypothesize that women with AVW prolapse would have the same vaginal wall biomechanical properties regardless of their weight.

To investigate the influence of elevated annealing temperature (70–90 °C) on the mechanical properties of coiled helical PLLA stents. PLLA 0.10 mm fibers and Ø3 mm × 12 mm stents were fabricated and annealed at 70, 80 and 90 °C for 25 min. The mechanical properties of the fibers and the functional characteristics of the stents were measured and compared to a control group processed at 21 °C. The stents were mounted, expanded and relaxed using an Ø3 mm × 2 cm balloon catheter to a maximum balloon pressure of 12 atm. Measurements of stent diameter, length, and the balloon pressure were used to determine the effective circumferential strain, incremental stiffness, elastic recoil, and lengthening of the stents. Stents exhibited progressively higher incremental stiffness with annealing temperature, higher collapse resistance and a reduction in elastic recoil vs. controls. Single fiber mechanical properties decreased as annealing temperature increased. Differential scanning calorimetry revealed crystallinity increased within thermally annealed stent fibers compared with controls. SEM examination indicated thermally annealed stents underwent less twisting than controls during balloon-induced unfurling. Thermal annealing of PLLA fibers and stents between 70 and 90 °C induced changes in crystalline structure, thereby favorably influencing fiber stress–strain behavior and stent expansion characteristics.

An iCAST covered balloon-expandable stent (Maquet Getinge Group, Hudson, NH) has been used in the superior mesenteric artery (SMA) to treat a variety of pathology and most recently for visceral stenting in fenestrated endovascular aortic repair (FEVAR). Stenting has primarily been investigated by bench studies involving finite element analysis in the coronaries; however, further explanation of the mechanical behavior has not been performed. This study examined Atrium stent expansion using a pseudoballoon and then a second simulation expanding the stent into a theoretical SMA.

This study examined the influence of powder composition and morphology on the penetration of Gray and White ProRoot mineral trioxide aggregate (GMTA, WMTA) and calcium hydroxide (CH) into open dentin tubules. GMTA, WMTA, and CH particle dimensions were analyzed by flow particle image analysis (FPIA). Penetration of open dentin tubules into dentin discs was studied by scanning electron microscopy. Five samples of each material were randomly selected and prepared for this study. The GMTA averages for length (μm), width (μm), perimeter (μm), and aspect ratio were 1.94 ± 1.65, 1.43 ± 1.19, 5.61 ± 4.27, and 0.76 ± 0.14, respectively. Corresponding averages for WMTA were 2.04 ± 1.87, 1.49 ± 1.33, 5.88 ± 4.81, and 0.76 ± 0.14, and for CH were 2.26 ± 1.99, 1.62 ± 1.46, 6.70 ± 5.60, and 0.74 ± 0.15, respectively. The rank order of the averages for particle length, width and perimeter from the largest to the smallest material was CH > WMTA > GMTA. The rank order of the averaged aspect ratios was GMTA > WMTA > CH. SEM showed that all three materials, when deposited and agitated on dentin discs, penetrated the open dentin tubules. Tubule occlusion occurred as particle surface concentrations increased. Significant differences in particle length, width, perimeter, and aspect ratio were observed for GMTA, WMTA, and CH (P < 0.0001 in all cases). All particle types penetrated into open tubules when agitated on dentin discs; all tubules were eventually occluded as particle concentrations grew. (J Oral Sci 56, 287-293, 2014).

Bioresorbable stents with limited functional lifetimes and with drug delivery capabilities are desired. Various methods have been investigated to induce porosity in bioresorbable polymeric stent fibers, thereby to permit increased drug reservoir capacity versus polymer-coated metal stents. We developed microporous surface layers on PLLA fibers to serve as the drug reservoir, but found that impurities, the use of chemicals, and multiple step procedures associated with our, and other published methods limited utility. Thus we investigated theoretically attractive CO 2 blowing methods, in which gas under pressure and temperature induces porosity. We report the results of initial studies of CO 2-induced porosity in PLLA stent fibers.

OBJECTIVE:In-vivo measurement of the viscoelastic properties of the prolapsed anterior vaginal wall (AVW) in post-menopausal women undergoing cystocele repair. STUDY DESIGN:A BTC-2000 cutometer-like instrument was introduced during vaginal repair of symptomatic stage 2-3 AVW prolapse. Under anesthesia, 10-mm orifice probe was applied to the AVW at the level of the bladder neck. A suction pressure ramp (0 to -147 mmHg in 6s) was delivered causing tissue uplift, followed by immediate release to 0 mmHg, measuring tissue relaxation for 20s. Similar measurements were performed over the suprapubic region (SP) for comparison purpose. The rate of tissue recovery was obtained by fitting a Voigt model to the data and expressing results as the ratio E/η [(spring modulus E)/(dashpot viscosity η)]. The effective strain energy (SE) was calculated from the pressure-uplift data and evaluated from initiation to: (1) maximum storage in tissue at peak vacuum; (2) tissue recovery after vacuum release; (3) net SE loss over the entire loading-unloading cycle. RESULTS:In 22 women, higher AVW peak and residual tissue uplift values, and lower E/η ratios were found compared with SP results. The AVW stored less elastic strain energy at peak vacuum than did the SP, and AVW net energy loss over the uplift-recovery cycle was greater than for SP controls. Not only was the AVW more compliant than the SP, with higher viscous damping, but the tissue was also less able to store recoverable energy upon distension. CONCLUSION:Such in-vivo measurements quantify the biomechanical properties of the prolapsed AVW and may assist in its management.

The design and development of bioresorbable stents tailored for treatment of pediatric patients with congenital heart disease is described. First, we examined the mechanical properties of thermally annealed PL-32 and PL-18 PLLA fibers using an Instron 5565 tensiometer. Stent designs ranging from 3 to 6 mm diameter and up to 15 mm length were examined. We adapted a winding jig to enable fabrication of coiled stents consisting of double-opposed helices. Double-opposed helical stents were thermally annealed for strength and flexibility. Following winding, stents were crimped on appropriately sized balloon catheters, and then expanded in a 37 °C water bath. Mechanical characteristics were measured as a function of stent size and design. PL-32 fiber has stronger mechanical properties with a 33% increase in stiffness. The opposing coil design improves stent expansion for larger stent designs. In addition, the stiffness of small diameter double-opposed helical stents was higher than values for the larger diameter stents hence having higher collapse pressure 1.07 ± 0.02 atm and the resistance to external pressure-induced collapse for larger diameter stents was lower decreasing to 0.63 ± 0.02 atm. The larger deformations at larger diameters were experienced since mechanical strain in the stent fibers is increased under these conditions. This led to increased twisting of the coils and higher striation angle measurements ranging from 17.5° to 26.7° from smaller to larger stents. The large diameter double opposed helix stents showed larger axial shortening of 3–3.5% and higher elastic recoil increase of 1.12%. The PL-32 stents also showed a slower degradation of 5% over 6 months. Modulating the number of coils within the double helical stent design and winding in opposing directions favorably affects stent mechanical properties.

A sustained release formulation for the therapeutic peptide thymosin β4 (Tβ4) that can be localized to the heart and reduce the concentration and frequency of dose is being explored as a means to improve its delivery in humans. This review contains concepts involved in the delivery of peptides to the heart and the synthesis of polymer microspheres for the sustained release of peptides, including Tβ4. Initial results of poly(lactic‐co‐glycolic acid) microspheres synthesized with specific tolerances for intramyocardial injection that demonstrate the encapsulation and release of Tβ4 from double‐emulsion microspheres are also presented.

Molecular and cellular interactions with foreign surfaces can be noninvasively measured by isotope imaging techniques. Long available for probing cell behavior, these techniques are now employed in molecular studies of disease progression, such as Alzheimer’s [1]. This paper reviews results obtained by noninvasive dual label gamma scintigraphy for the transient adhesion of platelets and neutrophils to pump-oxygenators during cardiopulmonary bypass (CPB). In this application, characteristic cell-foreign surface adhesion and release patterns are observed during CPB in the pig, as a function of oxygenator design and surface chemistry. Cell distributions in internal organs post-CPB are also affected by these processes. This method can be adapted to other settings where the understanding of protein-cell interactions with native and foreign surfaces is at issue, including fibrinogen-cell interactions, bacterial colonization, etc.

INTRODUCTION: Biodegradable stents designed for use in infants would offer tremendous advantages by avoiding a permanent implant in a growing child. The bench testing and initial results of a coil ...