A zero-valent palladium cluster-organic framework.

Acquiring spatial control of nanoscopic metal clusters is central to their function as efficient multi-electron catalysts. However, dispersing metal clusters on surfaces or in porous hosts is accompanied by an intrinsic heterogeneity that hampers detailed understanding of the chemical structure and its relation to reactivities. Tethering pre-assembled molecular metal clusters into polymeric, crystalline 2D or 3D networks constitutes an unproven approach to realizing ordered arrays of chemically well-defined metal clusters. Herein, we report the facile synthesis of a {Pd3} cluster-based organometallic framework from a molecular triangulo-Pd3(CNXyl)6 (Xyl = xylyl; Pd3) cluster under chemically mild conditions. The formally zero-valent Pd3 cluster readily engages in a complete ligand exchange when exposed to a similar, ditopic isocyanide ligand, resulting in polymerization into a 2D coordination network (Pd3-MOF). The structure of Pd3-MOF could be unambiguously determined by continuous rotation 3D electron diffraction (3D-ED) experiments to a resolution of ~1.0 Å (>99% completeness), showcasing the applicability of 3D-ED to nanocrystalline, organometallic polymers. Pd3-MOF displays Pd03 cluster nodes, which possess significant thermal and aerobic stability, and activity towards hydrogenation catalysis. Importantly, the realization of Pd3-MOF paves the way for the exploitation of metal clusters as building blocks for rigidly interlocked metal nanoparticles at the molecular limit.

An experimental laboratory reactor for quantitative kinetic studies of disinfection byproduct formation using membrane inlet mass spectrometry.

RATIONALE: The type and quantity of environmentally problematic disinfection byproducts (DBPs) produced during chlorination of water depend on the natural organic matter and organic contaminants that raw water contains, and on the operational conditions of the drinking water treatment process. There is a need for a fast and quantitative method that determines which DBPs are produced and monitors the chemical dynamics during a drinking water treatment. METHODS: A small experimental chemical reactor (50 mL) was mounted directly onto the membrane inlet interface of a membrane inlet mass spectrometer (MIMS). In this setup, the membrane was the only separation between the reaction mixture in the chemical reactor and the open ion source of the mass spectrometer 2 cm away. Water samples to be chlorinated were placed in the reactor and the chlorination reaction was initiated by injection of hypochlorite. The formation of intermediates and products was monitored using either full-scan mass spectra or selected ion monitoring of relevant ions. RESULTS: An algorithm for analyte quantification was successfully developed for analysis of the complex mixtures of phenol (a model for waterborne organic compounds), chlorinated intermediates and trihalomethane products which simultaneously pass the membrane into the mass spectrometer. The algorithm is based upon the combined use of standard addition and an internal standard, and all analytes could be quantified at nanomolar concentrations corresponding to realistic water treatment conditions. Experiments carried out in the temperature range 15-60°C showed that the reaction dynamics change with operational parameters, for example in tap versus deionized water. CONCLUSIONS: We have successfully shown that an experimental laboratory reactor directly interfaced with a MIMS can be used for quantitative monitoring of the chemical dynamics during a water treatment. This technique could provide rapid assistance in the optimization of operating parameters for minimizing DBP production.

Cooperative Co-Activation of Water and Hypochlorite by a Non-Heme Diiron(III) Complex.

Aqueous solutions of the iron(III) complex of N,N,N'-tris(2-pyridylmethyl)ethylenediamine-N'-acetate (tpena) react with hypochlorite (ClO-) to produce the reactive high-valent [FeIV(O)(tpena)]+. Under catalytic conditions, in bicarbonate-buffered media (pH 8) with a set ionic strength (10 mM NaCl), kinetic analysis shows that two equivalents of [FeIV(O)(tpena)]+ per one ClO- are produced, with benign chloride ions the only byproduct. An unprecedented supramolecular activation of ClO- by {(HCO3)⊂[(tpena)FeIII(µ-O)FeIII(Htpena)]}2+ is proposed. This mode of activation has great advantage for use in the catalytic oxidation of C-H bonds in water since: (i) the catalyst scaffold is protected from oxidative degradation and (ii) undesirable radical side reactions which produce toxic chlorinated compounds are circumvented by this novel coactivation of water and ClO-. The unique activation mechanism by the Fe-tpena system makes possible the destruction of organic contaminants as an add-on technology to water disinfection by chlorination, demonstrated here through (i) the catalytic oxidation of micropollutant metaldehyde, and (ii) mineralization of the model substrate formate. The resting-state speciation at pH 3, 5, 7, and 9, as well as the catalytically active iron speciation are characterized with Mössbauer and EPR spectroscopy and supported by DFT calculations. Our study provides fundamentally new insights into the design and activation mode of iron-based catalysts relevant to applications in water remediation.

Engineering the Oxidative Potency of Non-Heme Iron(IV) Oxo Complexes in Water for C-H Oxidation by a cis Donor and Variation of the Second Coordination Sphere.

A series of iron(IV) oxo complexes, which differ in the donor (CH2py or CH2COO-) cis to the oxo group, three with hemilabile pendant donor/second coordination sphere base/acid arms (pyH/py or ROH), have been prepared in water at pH 2 and 7. The νFe═O values of 832 ± 2 cm-1 indicate similar FeIV═O bond strengths; however, different reactivities toward C-H substrates in water are observed. HAT occurs at rates that differ by 1 order of magnitude with nonclassical KIEs (kH/kD = 30-66) consistent with hydrogen atom tunneling. Higher KIEs correlate with faster reaction rates as well as a greater thermodynamic stability of the iron(III) resting states. A doubling in rate from pH 7 to pH 2 for substrate C-H oxidation by the most potent complex, that with a cis-carboxylate donor, [FeIVO(Htpena)]2+, is observed. Supramolecular assistance by the first and second coordination spheres in activating the substrate is proposed. The lifetime of this complex in the absence of a C-H substrate is the shortest (at pH 2, 3 h vs up to 1.3 days for the most stable complex), implying that slow water oxidation is a competing background reaction. The iron(IV)═O complex bearing an alcohol moiety in the second coordination sphere displays significantly shorter lifetimes due to a competing selective intramolecular oxidation of the ligand.

Ingestion of gastrolith mineralized matrix increases bone volume and tissue volume in mouse long bone fracture model.

PURPOSE: Fracture healing often requires extended convalescence as the bony fragments consolidate into restored viable tissue for load-bearing. Development of interventions to improve healing remains a priority for orthopaedic research. The goal of this study was to evaluate the ability of a naturally occurring matrix of amorphous calcium carbonate to affect fracture healing in an uninstrumented long bone model. METHODS: Complete transverse fracture was induced in the fibula of mature mice, followed by daily gavage of crushed gastrolith from crayfish at doses of 0 (control), 1 (1 MG), and 5 (5 MG) mg/kg. At Day 17, bones and sera were harvested. RESULTS: Morphologically, the 1 MG treated group had greater bone volume (BV), and both 1 MG and 5 MG had greater tissue volume (TV) than control (p < 0.05), as determined by µCT; BV/TV and mineral density did not yield a statistical difference. Histologically, regional variations in mineralized matrix were evident in all specimens, indicating a broad continuum of healing within the callus. Among serum proteins, bone-specific alkaline phosphatase, indicative of active mineralization, was greater in 5 MG than control (p < 0.05). Sclerostin, an inhibitor of osteogenesis, was lower in 5 MG than control (p < 0.05), also suggestive of enhanced healing. CONCLUSIONS: An increase in bone volume, tissue volume and cellular signaling for osteogenesis at 17 days following fibula fracture in this mouse model suggests that gastrolith treatment holds potential for improving fracture healing. Further study at subsequent time points is warranted to determine the extent to which the increase in callus size with gastrolith treatment may accelerate restoration of tissue integrity.

The Effects of Continual Intermittent Parathyroid Hormone Treatment on Human Periodontal Ligament Fibroblasts in an In Vitro Wound Repopulation Model.

INTRODUCTION: Periodontal ligament fibroblasts (PDLFs) play a vital role in periodontal regeneration. Parathyroid hormone (PTH) is important in catabolic regulation on osteoclasts; it also has anabolic effects on hard tissue formation. Using an in vitro wound repopulation model, this study investigated the effect of continual intermittent administration of PTH on PDLFs wound repopulation. Methods and Materials: PDLFs were grown in 12-well plates and divided into 0 (control), 5, 10, 20, 40, and 80 nM of PTH treatments. A 3-mm wound was created on confluent and synchronized cells. Six PTH treatments were initiated using serum-free medium with supplements. Cell repopulation was measured at four time points: 5, 10, 15, and 20 days. RESULTS: A 5% increase wound repopulation showed an enhancement on day 10 for all treatment groups as compared to control groups. On days 15 and 20, treatment groups showed a decrease in proliferation and migration compared to controls with significant decreases at concentrations of 40 and 80 nM. CONCLUSION: Continual intermittent treatment with PTH has the potential to enhance proliferation and migration of PDLFs for wound repopulation at early time points. A dose-dependent correlation was seen with a positive trend on day 10 while a significant decrease on day 20.

Heat Generation Changes with Electrically Heated Pluggers after Multiple Autoclave Cycles at Different Operating Temperatures.

INTRODUCTION: Electrically heated pluggers are the most commonly used instruments during warm obturation techniques. This study aimed to evaluate the effect of sterilization and operating temperature settings on the heat generation of pluggers of various taper sizes. METHODS: Fifty pluggers were sterilized at 132°C for 25 minutes for a total of 150 cycles. One group (Autoclave200) consisted of 25 pluggers tested at an operating temperature setting of 200°C, whereas another group (Autoclave400) consisted of 25 pluggers tested at 400°C. The heat generation at their tip surface was measured with T-type thermocouples at 0, 50, 100, and 150 autoclave cycles. An unpaired t test was used to compare the time it took the pluggers to reach 60°C and the mean maximum temperature change. RESULTS: After 50 autoclave cycles, all of the 0.04 taper pluggers in Autoclave200 failed to reach 60°C. After 100 autoclave cycles, one of the 0.10 taper pluggers in Autoclave200 did not reach 60°C, and after 150 autoclave cycles, one of the 0.04 taper pluggers failed to generate any heat. The mean increase in the time to reach 60°C ranged from 1071-4004 milliseconds and 510-2074 milliseconds for Autoclave200 and Autoclave400, respectively. The mean maximum temperature change decreased by 13-29°C and 24-116°C for Autoclave200 and Autoclave400, respectively. CONCLUSIONS: After multiple autoclave cycles and higher operating temperature use, the electrically heated pluggers transferred less heat to the tip surface, potentially making them less effective.

Synthesis and structural, redox and photophysical properties of tris-(2,5-di(2-pyridyl)pyrrolide) lanthanide complexes.

A first series of lanthanide complexes of tris(dipyridyl)pyrrolide ligands has been prepared. The [Ln(dppR1,R2)3] complexes (Ln = La(iii), Sm(iii), Eu(iii), Gd(iii) and Yb(iii); and dppR1,R2 = 2,5-di(2-pyridyl-3-(R1)-4-(R2)) pyrrolide) have been isolated and their structures and photophysical and redox properties characterised, both in the solid-state and in solution. In the complexes, the three dpp- ligands form a distorted tricapped trigonal prismatic coordination geometry about the lanthanide ions, with the antiparallel isomer observed in the solid state for non-symmetric (dppCO2Me,Me)-. However, 1H NMR spectroscopy of the diamagnetic and paramagnetic [Ln(dppR1,R2)3] complexes in d6-benzene solution reveal evidence for a statistical distribution of all possible isomers. Time-resolved luminescence studies suggest that the dpp- ligand (with triplet excited state T1 energy at 18 622 cm-1) sensitises red emission from [Eu(dppCO2Me,Me)3] and near-infrared emission from [Yb(dppCO2Me,Me)3] through the antenna effect. Cyclic voltammetry reveals three consecutive, reversible, one-electron oxidation processes for each [Ln(dppR1,R2)3] complex, corresponding to oxidations of each dpp- ligand between 0.3-0.8 V vs. E1/2 (Fc+/0), and for [Eu(dppCO2Me,Me)3] the EuIII/II couple was -2.099 V vs. E1/2 (Fc+/0).

Effect of Sodium Lauryl Sulfate (SLS) on Primary Human Gingival Fibroblasts in an In Vitro Wound Healing Model.

OBJECTIVES: Sodium lauryl sulfate (SLS) is a surfactant used to decrease the surface tension of water. Most commercially available dentifrices contain 0.5-2.0% SLS. This study investigated the potential effect of SLS on oral wound healing using primary human gingival fibroblasts (HGFs). METHODS: HGFs cells were grown in12-well culture plates in DMEM medium. A 3 mm wound was created on confluent HGFs. The cells were challenged with 0 (the control group), 0.01, 0.02, 0.03, 0.04, or 0.05% SLS-containing media once daily for 2 minutes. The cells were stained on day 0, 2, 4, 6 and 8. The percent of wound fill area was measured. RESULTS: On day 2, 4, 6, and 8, the wound fill of the control group (0% SLS) was 15, 35, 67 and 98%, respectively; at 0.01% SLS, it was 10, 20, 65 and 84%; at 0.02%, it was 7, 10, 15 and 25%; at 0.03% SLS, it was only 5% and 8% on day 2 and 4. CONCLUSION: Our results showed a dose- and time-dependent inhibition on HGFs wound fill by SLS; however, future in vivo studies are needed to validate if our in vitro findings using SLS-free dentifrices to avoid the potential delay of wound healing.

Predictable Substituent Control of CoIII/II Redox Potential and Spin Crossover in Bis(dipyridylpyrrolide)cobalt Complexes.

A family of five easily prepared tridentate monoanionic 2,5-dipyridyl-3-(R1)-4-(R2)-pyrrolide anions (dppR1,R2)-, varying in the nature of the R1 and R2 substituents [R1, R2 = CN, Ph; CO2Et, CO2Et; CO2Me, 4-Py; CO2Me, Me; Me, Me], has been used to generate the analogous family of neutral [CoII(dppR1,R2)2] complexes, two of which are structurally characterized at both 100 and 298 K. Both the oxidation and spin states of these complexes can be switched in response to appropriate external stimuli. All complexes, except [CoII(dppMe,Me)2], exhibit gradual spin crossover (SCO) in the solid state, and SCO activity is observed for three complexes in CDCl3 solution. The cobalt(II) centers in the low spin (LS) complexes are Jahn-Teller tetragonally compressed along the pyrrolide-Co-pyrrolide axis. The complexes in their high spin (HS) states are more distorted than in the LS states, as is also usually the case for SCO active iron(II) complexes. The reversible CoIII/II redox potentials are predictably tuned by choice of substituents R1 and R2, from -0.95 (Me,Me) to -0.45 (CN,Ph) V vs Fc+/Fc, with a linear correlation observed between E1/2(CoIII/II) and the Swain-Lupton parameters of the pyrrolide substituents.

A Strain-Deformation Nexus within Pincer Ligands: Application to the Spin States of Iron(II) Complexes.

The substitution of a pyrrolide ring for one (or more) pyridyl rings within the ubiquitous terpyridine (tpy, A) scaffold results in more open geometries of the pyridine-pyrrolide chelate ligands. DFT calculations (B3LYP-GD3BJ/6-31G**) demonstrate that the more open geometries of the unbound ligands are mismatched with the "pinched in" geometries required to chelate transition metal ions (e.g., Zn2+). The strain which builds within these ligands (Δ EL(strain)) as they bind transition metal ions can be related to changes in a single geometric parameter: the separation between the two terminal N atoms (ρ). This relationship applies more generally to other three-ringed tridentate pincer ligands, including those with different donor groups. The approach was applied to homoleptic iron(II) complexes to investigate the contribution of the steric effects operating within the ligands to the different magnetic properties, including spin crossover (SCO) activities, of these systems.

Effect of a Benzalkonium Chloride Surfactant-Sodium Hypochlorite Combination on Elimination of Enterococcus faecalis.

INTRODUCTION: The purpose of this investigation was to determine the effect of a sodium hypochlorite-surfactant combination on the removal of Enterococcus faecalis from infected teeth. METHODS: Sixty-four extracted human single canal anterior teeth were prepared with rotary instrumentation and sterilized. Teeth were divided into 4 groups, N = 16. Three experimental groups were inoculated with E. faecalis and cultured for 21 days before use: positive control group, no irrigation; NaOCl group, irrigated with 5 mL 6% NaOCl; and NaOCl/BAK group, irrigated with 5 mL 6% NaOCl/0.008% benzalkonium chloride (BAK). The negative control group received medium only and no inoculate. Paper point sampling of the canals was obtained before irrigation (S1) for all 4 groups and for 2 groups after irrigation (S2) to determine remaining colony-forming units. After sampling, all teeth were split in half and evaluated for bacterial viability colony-forming units and penetration of dentinal tubules by using fluorescent vital dye staining and confocal laser scanning microscopy. RESULTS: Comparison of pre-irrigation and post-irrigation paper point samples from the 2 irrigated groups showed a significant reduction in bacterial canal load (P < .001, Kruskal-Wallis), with a significantly lower load in the NaOCl/BAK group than in the NaOCl group (P = .001, Mann-Whitney U test); 68.8% of the NaOCl/BAK samples gave no recoverable counts. In contrast, no significant difference between these groups was found for counts recovered from dentin. Confocal laser scanning microscopy showed no differences in tubule penetration. CONCLUSIONS: The addition of BAK to NaOCl significantly reduced the number of remaining bacteria within the canal after irrigation compared with NaOCl alone.

In vitro study of the adverse effect of nicotine and physical strain on human gingival fibroblasts as a model of the healing of wounds commonly found in the military.

BACKGROUND: Significant adverse effects on fibroblast growth and metabolism are observed with nicotine. We investigated the synergistic effects of nicotine and cyclical mechanical strain (CMS) on human gingival fibroblasts (HGFs) in a wound-healing model. METHODS: HGFs were isolated and grown in Dulbecco's modified Eagle's medium. Three-millimeter wounds were created on a confluent cell monolayer grown in a media containing 0, 1, 2, or 4 mM nicotine, with or without CMS. The applied deformation regimen remains constant for 6 days. On days 1, 2, 4, and 6, the cells were stained with hematoxylin and eosin Y for the evaluation of wound repopulation. RESULTS: The application of CMS alone demonstrates a biphasic response, with an initial stimulatory effect on wound repopulation (days 1-2) and less repopulation during the later phase (days 4-6). The addition of nicotine clearly demonstrated a time and inverse dose-dependent relationship on wound repopulation, with no effect during the early phase and reduced wound repopulation during the later phase. CONCLUSIONS: Initial treatment of HGF wounds with CMS resulted in faster wound repopulation regardless of nicotine presence. By day 6, wound healing of HGF exposed to both nicotine and CMS is delayed. These findings suggest that CMS and nicotine may affect fibroblasts and delay wound healing at other sites in the body as well.

The effectiveness of endodontic solvents to remove endodontic sealers.

Dental emergencies negatively affect troop readiness, especially during combat. Endodontic retreatment, when required, is especially challenging when the removal of endodontic sealer is required. In this study, we investigated the effectiveness of synthetic endodontic solvents to remove endodontic sealers. Fifty capillary tubes (2.7 mm ID×22 mm L), each filled to 15 mm with either Roth 801, AH Plus, MetaSEAL, or gutta-percha, were stored at 75% humidity for 14 days at 37°C. Ten capillary tubes containing each sealer were treated with either chloroform, xylene, EndoSolv R, EndoSolv E, or no solvent, and then penetrated with D3 ProTaper Universal Retreatment file on the same day. The time for the file to penetrate the length of each sealer was recorded, and the data statistically analyzed. Roth 801 failed to set and was not tested. The file took 3.4±0.1, 4.8±0.3, 5.7±0.4, 4.5±0.2, and 10.6±1.0 seconds (mean±SD) to penetrate gutta-percha using chloroform, xylene, EndoSolv R, EndoSolv E, or no solvent, respectively, and was performed by one endodontic resident at one sitting. The time for penetration of gutta-percha with any solvent was significantly faster (p≤0.05) than for AH Plus or MetaSEAL.The time for AH Plus ranged from 23.1±1.0 to 81.5±4.5 seconds. The time for MetaSEAL ranged from 97.2±6.1 to >180 seconds. EndoSolv E was the most effective solvent for AH Plus. It took significantly more time to remove MetaSEAL than AH Plus, regardless of the solvent used. Our study indicated that the use of the proper endodontic solvent makes complete removal of a sealer much more effective during retreatment.

Histologic Evaluation of Osseous Regeneration Following Combination Therapy With Platelet-Rich Plasma and Bio-Oss in a Rat Calvarial Critical-Size Defect Model.

Platelet-rich plasma (PRP) is an autogenous source of growth factors shown to facilitate human bone growth. Bio-Oss, an osteoconductive xenograft, is used clinically to regenerate periodontal defects, restore dental alveolar ridges, and facilitate sinus-lift procedures. The purpose of this study was to analyze whether a combination of PRP and Bio-Oss would enhance bone regeneration better than either material alone. PRP and/or Bio-Oss were administered in an 8-mm critical-size defect (CSD) rat calvarial model of bone defect between 2 polytetrafluoroethylene membranes to prevent soft tissue incursion. Eight weeks after the induction of the CSD, histologic sections were stained with hematoxylin and eosin stain and analyzed via light microscopy. Qualitative analyses revealed new bone regeneration in all 4 groups. The Bio-Oss and PRP plus Bio-Oss groups demonstrated greater areas of closure in the defects than the control or PRP-only groups because of the space-maintaining ability of Bio-Oss. The groups grafted with Bio-Oss showed close contact with new bone growth throughout the defects, suggesting a stronger graft. The use of PRP alone or in combination with Bio-Oss, however, did not appear to enhance osseous regeneration at 8 weeks. Areas grafted with Bio-Oss demonstrated greater space-maintaining capacity than controls, and PRP was an effective vehicle for placement of the Bio-Oss. However, at 8 weeks this study was unable to demonstrate a significant advantage of using PRP plus Bio-Oss over using Bio-Oss alone.

Cervical VEMP threshold response curve in the identification of Ménière's disease.

PURPOSE: To investigate the sensitivity/specificity of a shift upward in the most sensitive frequency of the cervical vestibular evoked myogenic potential (cVEMP) threshold-response curve in the identification of Ménière's disease (MD). A secondary purpose was to investigate the clinical characteristics that had an impact on the sensitivity/specificity and to adjust the criteria for a positive shift upward in the cVEMP curve to maximize performance of the test. RESEARCH DESIGN: A retrospective review of patients diagnosed with MD and those without MD. STUDY SAMPLE: Two hundred ninety-four patients met the inclusion criteria of symptom complaints of spontaneous events of vertigo and a full vestibular and balance evaluation with cVEMP threshold-response curve testing. Two hundred six of these patients were diagnosed with MD, and 88 patients were determined to be non-MD. DATA COLLECTION AND ANALYSIS: Review of the patients' medical records was used to extract data on the results of the cVEMP curve, age, gender, duration from time of onset of spontaneous events, pure tone average from hearing test, and water caloric asymmetry. Student's t-test, χ² test, receiver operating characteristic (ROC) curve with area under the curve (AUC), Pearson correlation coefficient, and sensitivity/specificity from 2 × 2 tables were all used in the analysis. RESULTS: Basic sensitivity/specificity for a shift upward in the most sensitive frequency to 1000 Hz in the cVEMP threshold-response curve was 0.47/0.64 respectively. Clinical characteristics that were found to have a significant impact on the sensitivity/specificity were age equal to or above 60 yr and a caloric asymmetry ≥25%. Various combinations of age and caloric with the requirement of a shift upward in the cVEMP curve most sensitive frequency to 1000 Hz resulted in significant but modest improvements in sensitivity/specificity. However, the overall performance was not shown acceptable for routine clinical use with maximum sensitivity at 0.73. Therefore, placing an emphasis on specificity over sensitivity results showed specificity of 0.95 for those under 60 yr and 0.90 for those 60 yr of age or older with sensitivity at 0.20, but only in the context of a ≥25% caloric asymmetry. CONCLUSIONS: We recommend the use of the shift upward to 1000 Hz with a caloric asymmetry as the clinical protocol to maximize the use of the cVEMP threshold-response curve for assistance in the identification of MD, in the context of a ≥25% caloric asymmetry. This implies that if the test is negative no interpretation of identification of MD can be made. If the test is positive the results can be used to increase the argument for MD since the probability of the result being a false positive is only 5-10%.

Content analysis of five occupational therapy journals, 2006-2010: further review of characteristics of the quantitative literature.

OBJECTIVE. To analyze the content of publications in 5 occupational therapy journals to determine the strengths and weaknesses of the literature base from 2006 to 2010. METHOD. A content analysis for 2006 through 2010 of the American Journal of Occupational Therapy (AJOT), Australian Occupational Therapy Journal (AOTJ), British Journal of Occupational Therapy (BJOT), Canadian Journal of Occupational Therapy (CJOT), and Scandinavian Journal of Occupational Therapy (SJOT) was completed. RESULTS. AJOT and SJOT had the highest percentage of articles focusing on physical disabilities, whereas a majority of articles in AOTJ, BJOT, and CJOT focused on education. SJOT published articles with the highest median number of participants in all research designs excluding descriptive studies. The majority of the research articles were descriptive for all journals. CONCLUSION. From 2006 to 2010, AJOT provided stronger evidence conducted at higher levels than the other journals by publishing more articles investigating interventions used to support clinical practice.

Gender and age differences in growth factor concentrations from platelet-rich plasma in adults.

The use of platelet-rich plasma (PRP) to facilitate healing of orthopedic-related injuries has gained popularity; however, the clinical benefits are not consistent. Differences may result from variations in growth factor (GF) levels in normal populations. The purpose of this study was to determine if GF levels present in activated PRP preparations differed by gender and age (≤ 25 versus >25 years) in a healthy population (N = 102). All GFs analyzed (epidermal growth factor [EGF], hepatocyte growth factor [HGF], insulin growth factor-1 [IGF-1], platelet-derived growth factor-AB [PDGF-AB], platelet-derived growth factor-BB [PDGF-BB], transforming growth factor beta-1 [TGFß-1], and vascular endothelial growth factor) had higher levels for females and for those ≤ 25 years old. Of the GFs tested, four of seven were significantly higher (p < 0.05) for females (EGF, HGF, IGF-1, PDGF-BB), the most significant being IGF-1 (female, 85.0; male, 69.3 ng/mL; p < 0.01). Five of seven GFs achieved significance (p < 0.05) for people ≤ 25 years old (EGF, IGF-1, PDGP-AB, PDGF-BB, and TGFß-1), with IGF and PDGF-AB achieving p < 0.001 (≤ 25 years, 85.1; >25 years, 56.8, and ≤ 25 years, 7.66; >25 years, 5.77 ng/mL, respectively). Finally, for both genders, most of the GFs were positively correlated with all GFs. This study demonstrated that both age and gender account for variations in specific GFs present in PRP, and this may partially explain some of the inconsistent results of PRP clinical trials.

Effect of rhBMP-2 dose on bone formation/maturation in a rat critical-size calvarial defect model.

BACKGROUND: Application of recombinant human bone morphogenetic protein-2 (rhBMP-2) has been associated with significant adverse events in craniofacial settings, including swelling and seroma formation. Recent work has demonstrated an inverse relationship between bone formation/maturation and rhBMP-2 dose, frequency/severity of adverse events increasing with rising dose. OBJECTIVE: The objective of this study was to determine the most effective dose for rhBMP-2 soak-loaded onto an absorbable collagen sponge (ACS) carrier for bone formation/maturation using an established defect model. METHODS: One hundred sixty-eight outbred male Sprague-Dawley rats, age 11-13 weeks, weight 325-375 g randomized into seven groups of 24 subdivided into groups of eight, were used to provide radiographic and light microscopy observations of bone formation/maturation and aberrant healing events at 2, 4 and 8 weeks following application of rhBMP-2/ACS into critical-size, ø8-mm, through-through, calvarial osteotomy defects for a dose of 1.25, 2.5, 5.0, 10.0 and 20.0 µg rhBMP-2/defect, or serve as ACS or sham-surgery controls. RESULTS: rhBMP-2 dosages ≥ 2.5 µg/defect showed histological defect closure >90% within 2 weeks, and complete resolution within 4 weeks. Adverse healing events including swelling, excessive bone formation or seroma formation could not be determined with certainty in this defect model. Notably ACS control sites showed complete defect closure at the 8-week healing interval. CONCLUSIONS: rhBMP-2/ACS accelerates local bone formation in the rat critical-size through-through calvarial defect model once reaching an osteoinductive dose threshold. This threshold may already be reached at a 1.25-/2.5-µg dose in this model. No further enhancement to bone formation/maturation may be observed adding rhBMP-2 above the 2.5-µg dose. The 1.25-20.0 µg dose range did not invoke appreciable aberrant healing events.