Fracture healing in protease‐activated receptor‐2 deficient mice

Protease‐activated receptor‐2 (PAR‐2) provides an important link between extracellular proteases and the cellular initiation of inflammatory responses. The effect of PAR‐2 on fracture healing is unknown. This study investigates the in vivo effect of PAR‐2 deletion on fracture healing by assessing differences between wild‐type (PAR‐2^+/+) and knock‐out (PAR‐2^?/?) mice. Unilateral mid‐shaft femur fractures were created in 34 PAR‐2^+/+ and 28 PAR‐2^?/? mice after intramedullary fixation. Histologic assessments were made at 1, 2, and 4 weeks post‐fracture (wpf), and radiographic (plain radiographs, micro‐computed tomography (µCT)) and biomechanical (torsion testing) assessments were made at 7 and 10 wpf. Both the fractured and un‐fractured contralateral femur specimens were evaluated. Polar moment of inertia (pMOI), tissue mineral density (TMD), bone volume fraction (BV/TV) were determined from µCT images, and callus diameter was determined from plain radiographs. Statistically significant differences in callus morphology as assessed by µCT were found between PAR‐2^?/? and PAR‐2^+/+ mice at both 7 and 10 wpf. However, no significant histologic, plain radiographic, or biomechanical differences were found between the genotypes. The loss of PAR‐2 was found to alter callus morphology as assessed by µCT but was not found to otherwise effect fracture healing in young mice. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1271–1276, 2012     

Interfacial shear strength of bioactive‐coated carbon fiber reinforced polyetheretherketone after in vivo implantation

Despite the excellent osseointegration of carbon‐fiber‐reinforced polyetheretherketone (CFR/PEEK) with a surface hydroxyapatite (HA) coating, the bone‐implant interfacial shear strength of HA‐coated CFR/PEEK after osseointegration is unclear. We examined the interfacial shear strength of HA‐coated CFR/PEEK implants after in vivo implantation in a rabbit femur‐implant pull‐out test model. HA coating was performed by a newly developed method. Uncoated CFR/PEEK, HA‐coated blasted titanium alloy, and uncoated blasted titanium alloy were used as control implants. The implants were inserted into drilled femoral cortex, and pull‐out tests were conducted after 6 and 12 weeks of implantation to determine maximum interfacial shear strength. The HA‐coated CFR/PEEK (15.7 ± 4.5 MPa) and HA‐coated titanium alloy (14.1 ± 6.0 MPa) exhibited significantly larger interfacial shear strengths than the uncoated CFR/PEEK (7.7 ± 1.8 MPa) and the uncoated titanium alloy (7.8 ± 2.1 MPa) at 6 weeks. At 12 weeks, only the uncoated CFR/PEEK (8.3 ± 3.0 MPa) exhibited a significantly smaller interfacial shear strength, as compared to the HA‐coated CFR/PEEK (17.4 ± 3.6 MPa), HA‐coated titanium alloy (14.2 ± 4.8 MPa), and uncoated titanium alloy (15.0 ± 2.6 MPa). Surface analysis of the removed implants revealed detachment of the HA layer in both the HA‐coated CFR/PEEK and titanium alloy implants. The proposed novel HA coating method of CFR/PEEK significantly increased interfacial shear strength between bone and CFR/PEEK. The achieved interfacial shear strength of the HA‐coated CFR/PEEK implant is of the same level as that of grit‐blasted titanium alloy with HA. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1618–1625, 2012     

Trimethylamine N‐oxide as a media supplement for cartilage tissue engineering

Supplements added to the culture media (e.g., growth factors and dexamethasone) have been successful in improving mechanical and biochemical properties of engineered cartilage towards native values. Trimethylamine N‐oxide (TMAO), a natural osmolyte found in shark cartilage, is thought to induce protein folding, and counteracts the destabilizing effect of the high concentrations of urea stored by sharks. The objective of this study was to investigate the use of TMAO as a media supplement for promoting growth of functional engineered cartilage in culture. In the first study, TMAO was added to the culture media for the first 14 days in culture and concentrations of 0–200 mM were evaluated. In the second study, TMAO was supplemented to the culture media following chondroitinase ABC digestion, which has been previously shown to mediate an increased collagen content in engineered cartilage. A dose‐dependent response was observed with improved mechanical and biochemical properties for engineered constructs cultured with TMAO at concentrations of 5–100 mM. The Young's modulus of digested constructs cultured in TMAO was 2× greater than digested constructs cultured in the control medium and recovered to undigested control levels by day 42. In conclusion, these initial studies with TMAO as a media supplement show promise for improving the compressive mechanical properties, increasing extracellular matrix production, and increasing the recovery time following chABC digestion. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1898–1905, 2012     

Reference output tracking control for a flexible air‐breathing hypersonic vehicle via output feedback

This paper addresses the problem of reference output tracking control for the longitudinal model of a flexible air‐breathing hypersonic vehicle (FAHV) by utilizing the output feedback control approach. The dynamic characteristics of the FAHV along with the aerodynamic effects of hypersonic flight make the flight control of such systems highly challenging. Moreover, there exist some intricate couplings between the engine and flight dynamics as well as complex interaction between rigid and flexible modes in the longitudinal model. These couplings bring difficulty to the flight control design for the intractable hypersonic vehicle systems. This paper deals with the problem of reference output tracking control for the longitudinal model of the FAHV. By utilizing the trim condition information including the state of altitude, velocity, angle of attack, pitch angle, pitch rate and so on, the linearized model is established for the control design objective. Then, the reference output velocity and altitude tracking control design problem is proposed for the linearized model. The flexible models of the FAHV system are hardly measured because of the complex dynamics and the strong couplings of the FAHV. Thus, by using only limited flexible model information, the reference output tracking performance analysis criteria are obtained via Lyapunov stability theory. Then, based on linear matrix inequality optimization algorithm, the static output feedback controller is designed to stabilize the closed‐loop systems, guarantee a certain bound for the closed‐loop value of the cost function, and can make the control output achieve the reference velocity and altitude tracking performance. Subsequently, the condition of dynamic output feedback controller synthesis is given in terms of linear matrix inequalities and a numerical algorithm is developed to search for a desired dynamic output feedback controller which minimizes the cost bound and obtains the excellent reference altitude and velocity tracking performance simultaneously. The effectiveness of the proposed reference output tracking control method is demonstrated in simulation part. Furthermore, the superior reference velocity and altitude performance commands could be achieved via using static and dynamic output feedback controllers under lacking some unmeasured flexible states information in the measurement output vector. Copyright © 2011 John Wiley & Sons, Ltd.     

Anti‐gal antibodies in α1,3‐galactosyltransferase gene‐knockout pigs

Fang J, Walters A, Hara H, Long C, Yeh P, Ayares D, Cooper DKC, Bianchi J. Anti‐gal antibodies in α1,3‐galactosyltransferase gene‐knockout pigs. Xenotransplantation 2012; 19: 305–310. © 2012 John Wiley & Sons A/S. Abstract Serum anti‐galactose‐α1,3‐galactose (Gal) IgM and IgG antibody levels were measured by ELISA in α1,3‐galactosyltransferase gene‐knockout (GTKO) pigs (78 estimations in 47 pigs). A low level of anti‐Gal IgM was present soon after birth, and rose to a peak at 4–6 m, which was maintained thereafter even in the oldest pigs tested (at >2 yr). Anti‐Gal IgG was also present at birth, peaked at 3 m, and after 6 m steadily decreased until almost undetectable at 20 m. No differences in this pattern were seen between pigs of different gender. Total IgM followed a similar pattern as anti‐Gal IgM, but total IgG did not decrease after 6m. The data provide useful baseline data for future experimental studies in GTKO pigs, e.g., relating to the antibody response to WT pig allografts.     

α‐Actinin‐4 is involved in the process by which dexamethasone protects actin cytoskeleton stabilization from adriamycin‐induced podocyte injury

Aim: Glucocorticoid therapy has been used in childhood nephrotic syndrome since the 1950s, where the characteristic change is effacement of the actin‐rich foot process of glomerular podocytes. Recent studies have shown that glucocorticoids, in addition to their general immunosuppressive and anti‐inflammatory effects, have a direct effect on podocytes, regulate some apoptotic factors, and increase the stability of actin filaments. However, the precise mechanism(s) underlying the protective effects of glucocorticoids on podocytes remain unclear. It is known that adriamycin (ADR) can induce podocyte foot process effacement and trigger massive proteinuria in rodent models. However, few reports have examined the direct role of ADR in podocyte actin rearrangement in vitro. In this study, we investigated how ADR directly induced podocyte actin cytoskeleton rearrangement and further analyzed how dexamethasone prevented such injury. Methods: We used confocal microscopy to assess podocyte actin rearrangement. Western blot analysis and real‐time polymerase chain reaction were performed to measure the protein and mRNA levels of α‐actinin‐4. Results: We demonstrated that there was a time‐dependent ADR‐induced podocyte actin rearrangement with less than 12 h of ADR treatment in cultured podocytes. Dexamethasone could protect podocytes from ADR‐induced injury and also stabilize the expression of α‐actinin‐4. Conclusion: This study showed that dexamethasone had direct effects on podocytes: α‐actinin‐4 may be one of the potential target molecules.     

New clinical evidence of silodosin,an α1A selective adrenoceptor antagonist,in the treatment for lower urinary tract symptoms

Lower urinary tract symptoms associated with benign prostatic hyperplasia are highly prevalent in older men. Pharmacological treatment is the first‐line treatment for lower urinary tract symptoms associated with benign prostatic hyperplasia. The first choice in the pharmacological treatment for lower urinary tract symptoms associated with benign prostatic hyperplasia is the α₁‐adrenoceptor antagonists. Many α₁‐adrenoceptor antagonists are available in the world. Silodosin is an α₁‐adrenoceptor antagonist developed by Kissei Pharmaceutical, and has a specific selectivity for the α_1A‐adrenoceptor subtype. By antagonizing α_1A‐adrenoceptor in the prostate and urethra, silodosin causes smooth muscle relaxation in the lower urinary tract. As a result of the high affinity for the α_1A‐adrenoceptor than for the α_1B‐adrenoceptor, silodosin minimizes the propensity for blood pressure‐related adverse effects caused by blockade of α_1B‐adrenoceptor. The efficacy and safety of silodosin for treatment of lower urinary tract symptoms associated with benign prostatic hyperplasia was first reported by Japanese investigators in 2006. At present, silodosin is used in many countries. In the present review, we summarize the new clinical evidence for lower urinary tract symptoms associated with benign prostatic hyperplasia and introduce the data supporting the new clinical indications of silodosin.     

Periurethral injection of autologous adipose‐derived regenerative cells for the treatment of male stress urinary incontinence: Report of three initial cases

Objectives: To report a novel cell therapy using autologous adipose tissue‐derived regenerative cells for male stress urinary incontinence caused by urethral sphincteric deficiency, and the outcomes in the initial cases undergoing periurethral injection of adipose tissue‐derived regenerative cells. Methods: Three patients with moderate stress incontinence after radical prostatectomy and holmium laser enucleation of the prostate were enrolled. Adipose tissue‐derived regenerative cells were isolated from the abdominal adipose tissue by using the Celution system. Subsequently, the isolated adipose tissue‐derived regenerative cells, and a mixture of adipose tissue‐derived regenerative cells and adipose tissue were transurethrally injected into the rhabdosphincter and submucosal space of the urethra, respectively. Short‐term outcomes during a 6‐month follow up were assessed by a 24‐h pad test, a validated patient questionnaire, urethral pressure profile, transrectal ultrasonography and magnetic resonance imaging. Results: Urinary incontinence progressively improved after 2 weeks of injection up to 6 months in terms of decreased leakage volume, decreased frequency and amount of incontinence, and improved quality of life. Both maximum urethral closing pressure and functional profile length increased. Magnetic resonance imaging suggested a sustained presence of the injected adipose tissue. Enhanced ultrasonography showed a progressive increase in the blood flow to the injected area. No significant adverse events were observed peri‐ and postoperatively. Conclusion: These preliminary findings suggest that periurethral injection of the autologous adipose tissue‐derived regenerative cells is a safe and feasible treatment modality for male stress urinary incontinence.