The use of platelets to affect functional healing of an anterior cruciate ligament (ACL) autograft in a caprine ACL reconstruction model

Many anterior cruciate ligament (ACL) reconstructions have increased laxity postoperatively. We hypothesized that enhancing an ACL graft with a collagen‐platelet composite (CPC) would improve knee laxity and graft structural properties. We also hypothesized the platelet concentration in the CPC would affect these parameters. Twelve goats underwent ACL reconstruction with autologous patellar tendon graft. In six goats, a collagen‐platelet composite was placed around the graft (CPC group). In the remaining six goats, the collagen scaffold only was used (COLL group). Three goats were excluded due to complications. After 6 weeks in vivo, anterior–posterior (AP) laxity and tensile properties of the ACL reconstructed knees were measured and normalized against the contralateral intact knee. At a knee flexion angle of 30°, the average increase in AP laxity was 40% less in the CPC group than the COLL group (p = 0.045). At 60°, the AP laxity was 30% less in the CPC group, a difference that was close to statistical significance (p = 0.080). No differences were found between treatment groups with respect to the structural properties (p > 0.30). However, there were significant correlations between serum platelet concentration and AP laxity (R² = 0.643; p = 0.009), maximum load (R² = 0.691; p = 0.006), and graft stiffness (R² = 0.840; p < 0.001). In conclusion, use of a CPC to enhance healing of an allograft ACL reconstruction inversely correlated with early sagittal plane laxity and the systemic platelet count was highly predictive of ACL reconstruction graft strength and stiffness at 6 weeks. These findings emphasize the importance of further research on delineating the effect of platelets in treating of ACL injuries. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 631–638, 2009     

Platelet‐rich plasma alone is not sufficient to enhance suture repair of the ACL in skeletally immature animals: An in vivo study

In this study, we hypothesize that supplementation of suture repair of the anterior cruciate ligament (ACL) with platelet‐rich plasma (PRP) will improve the biomechanics of the repair. Six 30‐kg pigs underwent bilateral suture repair of the ACL. One side was treated with suture repair alone, while the contralateral side was treated with suture repair augmented with PRP. After 14 weeks in vivo, anterior–posterior (AP) knee laxity and the tensile properties of the repaired ligament were measured. The addition of PRP to the suture repairs did not improve AP knee laxity at 30° (p = 0.73) or 60° (p = 0.65). It also did not improve the maximum tensile load (p = 0.64) or linear stiffness (p = 0.42) of the ACL repairs after 14 weeks in vivo. The model had 80% power to detect a 30% improvement of biomechanical properties with PRP; thus, we are confident that a clinically meaningful effect as a result of adding PRP is unlikely. Use of PRP alone to supplement suture repair of the ACL is ineffective in this animal model. Published by Wiley Periodicals, Inc. J Orthop Res 27: 639–645, 2009     

Controversies and Concerns in Hemodialysis Series Editor: Marcello Tonelli: What’s Next After Fistula First: Is an Arteriovenous Graft or Central Venous Catheter Preferable When an Arteriovenous Fistula Is Not Possible?

Findings from observational studies have established that the arteriovenous fistula (AVF) is the preferred form of vascular access for chronic hemodialysis. Unfortunately, in a subset of patients with end-stage renal disease, an AVF cannot be placed or fails to mature. In these patients an alternate form of vascular access, either an arteriovenous graft (AVG) or central venous catheter (CVC) must be selected. In this review we discuss the findings and limitations of studies examining the effect of access type (AVG or CVC) on clinical endpoints including mortality, quality of life, occurrence of infections, as well as the impact of the different access types on resource requirements. Specifically, we examine whether findings from previous studies are valid and applicable to patients for whom an AVF is not possible, and outline the need for future randomized clinical trials addressing this question.     

Studies of the cellular uptake of hydrogel nanospheres and microspheres by phagocytes, vascular endothelial cells, and smooth muscle cells

Intensive research efforts have been placed on the development of nanospheres for targeted drug delivery for treating a variety of diseases, including coronary restenosis, cancer, and inflammatory reactions. Although most of these drug-bearing spheres are delivered via intravenous administration, little is known about the effect of sphere physical characteristics on the responses of vascular and blood cells. To find the answer, this work was aimed to investigate the cellular uptake of nanosized (100 nm) and microsized hydrogel spheres (1 microm) made of poly(N-isopropylacrylamide) by vascular cells and phagocytes under various flow conditions in vitro. We found that the cellular uptake of nanospheres depended on incubation times and sphere concentrations as well as on the introduced shear stress levels of the medium. Measurements of the intracellular-released fluorescence and confocal fluorescence microscopy revealed that nanospheres were internalized by endothelial cells and smooth muscle cells more than microspheres, whereas microspheres were rapidly taken up by phagocytes, especially at high concentration. Our results strongly suggest that hydrogel nanospheres are more effective as an intravascular delivery system compared to microspheres in the terms of vascular cellular uptake and biocompatibility.     

Prevalence of antibodies against orthopoxviruses among residents of Likouala region, Republic of Congo: evidence for monkeypox virus exposure

Monkeypox virus is a zoonotic orthopoxvirus (OPX) of west and central sub-Saharan Africa. We conducted a cross-sectional serosurvey in Likouala region, Republic of Congo to assess exposure to OPX. Whole blood was collected using Nobuto blood filter strips (NBFS). Titers of IgM and IgG to OPX were assessed using an enzyme-linked immunosorbent assay. Demographic and clinical characteristics were compared with serostatus using the chi-square test or Fisher's exact test. Multivariate logistic regression was performed to evaluate factors for independent association with serostatus. A total of 994 specimens were analyzed; the overall seroprevalence for OPX IgM was 1.7%. Age < 25 years reduced the likelihood of OPX exposure, and persons living in Ngangania village had independently higher odds (odds ratio = 33.5, 95% confidence interval = 7.2-166). Blood collection for serosurveys using NBFS is feasible and practical. Adult activities such as hunting and carcass preparation may play an important role in exposure to Monkeypox virus.     

Trends in use of opioids for non-cancer pain conditions 2000-2005 in commercial and Medicaid insurance plans: the TROUP study

Opioids are widely prescribed for non-cancer pain conditions (NCPC), but there have been no large observational studies in actual clinical practice assessing patterns of opioid use over extended periods of time. The TROUP (Trends and Risks of Opioid Use for Pain) study reports on trends in opioid therapy for NCPC in two disparate populations, one national and commercially insured population (HealthCore plan data) and one state-based and publicly-insured (Arkansas Medicaid) population over a six year period (2000–2005). We track enrollees with the four most common NCPC conditions: arthritis/joint pain, back pain, neck pain, headaches, as well as HIV/AIDS. Rates of NCPC diagnosis and opioid use increased linearly during this period in both groups, with the Medicaid group starting at higher rates and the HealthCore group increasing more rapidly. The proportion of enrollees receiving NCPC diagnoses increased (HealthCore 33%, Medicaid 9%), as did the proportion of enrollees with NCPC diagnoses who received opioids (HealthCore 58%, Medicaid 29%). Cumulative yearly opioid dose (in mg. morphine equivalents) received by NCPC patients treated with opioids increased (HealthCore 38%, Medicaid 37%) due to increases in number of days supplied rather than dose per day supplied. Use of short-acting Drug Enforcement Administration Schedule II opioids increased most rapidly, both in proportion of NCPC patients treated (HealthCore 54%, Medicaid 38%) and in cumulative yearly dose (HealthCore 95%, Medicaid 191%). These trends have occurred without any significant change in the underlying population prevalence of NCPC or new evidence of the efficacy of long-term opioid therapy and thus likely represent a broad-based shift in opioid treatment philosophy.     

Controlled release of chlorhexidine diacetate from a porous methacrylate system: supercritical fluid assisted foaming and impregnation

The release of chlorhexidine diacetate (CX) from a self-curing polymeric system based on poly(ethylmethacrylate) and tetrahydrofurfurylmethacrylate (PEM/THFM) was developed in this study. Supercritical fluid assisted impregnation and foaming was employed for preparing porous CX-PEM/THFM drug release system. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) show that the crystallinity of CX significantly decreased after supercritical processing, whilst Raman spectroscopy suggested a hydrogen bonding interaction between the CX and PEM in the product. A UV-Vis dissolution study revealed that the drug release rate is almost as seven times faster in the SCF processed drug delivery system than conventional cured samples.