Astronauts suffer from a loss of bone mass at a rate of 1.5% per month from lower regions of the body during the course of long-duration (>30 days) spaceflight, a phenomenon that poses important risks for returning crew. Conversely, a gain in bone mass may occur in non-load bearing regions of the body as related to microgravity-induced cephalad fluid shift. Representing non-load bearing regions with mouse calvaria and leveraging the STS-131 (15-day) and BION-M1 (30-day) flights, we examined spatial and temporal calvarial vascular remodeling and gene expression related to microgravity exposure compared between spaceflight (SF) and ground control (GC) cohorts. We examined parasagittal capillary numbers and structures in calvaria from 16 to 23 week-old C57BL/6 female mice (GC, n = 4; SF, n = 5) from STS-131 and 19–20 week-old C57BL/6 male mice (GC, n = 6; SF, n = 6) from BION-M1 using a robust isolectin-IB4 vessel marker. We found that the vessel diameter reduces significantly in mice exposed to 15 days of spaceflight relative to control. Capillarization increases by 30% (SF vs. GC, p = 0.054) in SF mice compared to GC mice. The vessel numbers and diameter remain unchanged in BION-M1 mice calvarial section. We next analyzed the parietal pro-angiogenic (VEGFA) and pro-osteogenic gene (BMP-2, DMP1, RUNX2 and OCN) expression in BION-M1 mice using quantitative RT-PCR. VEGFA gene expression increased 15-fold while BMP-2 gene expression increased 11-fold in flight mice compared to GC. The linkage between vascular morphology and gene expression in the SF conditions suggests that angiogenesis may be important in the regulation of pathological bone growth in non-weight bearing regions of the body. Short-duration microgravity-mediated bone restructuring has implications in planning effective countermeasures for long-duration flights and extraterrestrial human habitation.

Objectives In human menisci, we aimed to investigate whether calcium pyrophosphate crystal deposition (CPPD) affects biomechanical and quantitative MR properties, and their zonal distribution. Materials and Methods From 9 cadaveric knees, sectioned triangular meniscus pieces were harvested. Samples were classified into "normal" or "CPPD" groups based upon visual inspection. Micro computed tomography scan verified CPPD. Using magnetic resonance imaging, ultrashort echo time (UTE) T2* and spin echo (SE) T2, quantitative values in 3 zones (red, red-white, and white) were determined. Using biomechanical test, indentation forces in the same zones were determined. Effects of CPPD and meniscal zone on indentation force and quantitative MR values were compared. Results On UTE MRI scans, CPPD-affected menisci exhibited punctate dark regions, found mostly (92%) in avascular white and red-white zones. Indentation forces were significantly higher for CPPD samples in the red-white (all P < 0.02) and white (all P < 0.004) zones but not in the vascular red zone (all P > 0.2). Similarly, UTE T2* red zone values were similar between both groups (6.6 milliseconds, P = 0.8), whereas in the red-white and white zones, CPPD samples had significantly lower values (5.1 milliseconds, P = 0.005 to 0.007). In contrast, SE T2 values showed no difference with CPPD (P = 0.12 to 0.16). UTE T2*, but not SE T2, correlated significantly with indentation force (R = -0.29, P = 0.009). Conclusions Dark CPP deposits were detectable on UTE images featuring high signal intensity from surrounding meniscal tissue. Preliminary results indicate that CPP deposits were almost exclusively found in the avascular zones. Compared with normal, CPPD menisci featured higher indentation stiffness and lower UTE T2* values in the affected zones.

IntroductionOne of the primary health concerns faced by NASA astronauts on board the International Space Station is a decline in visual acuity. It is believed that increases in intracranial pressure (ICP) due to resistive exercise performed on the station's Advanced Resistive Exercise Device (ARED) may contribute to Spaceflight Associated Neuro‐Ocular Syndrome (SANS), also referred to as the Visual Impairment and Intracranial Pressure (VIIP) syndrome. In a manner similar to low level Valsalva exertion, it is hypothesized that ICP would increase during low level resistance exercise.MethodsSix healthy subjects (4 male, 2 female, age: 27 ± 10 years, weight: 77 ± 15 kg) were recruited to perform low‐level resistance exercises in both the seated and supine positions. A Cerebral Cochlear Fluid Pressure analyzer (CCFP) was used to noninvasively measure ICP by assessing tympanic membrane displacement (Vm) in the inner ear following an auditory stimulus. Increased values of Vm correspond to a decrease in ICP. After a 10‐minute acclimation period, a baseline measurement was taken with the subject at rest in the seated position. ICP was then measured during randomized, isometric, overhead shoulder holds with weights of 0lbs, 2lbs, and 5lbs (per hand). This procedure was then repeated in the supine position. ICP was also measured in the 15‐degree head down tilt (HDT) position following a 10‐minute acclimation period. Significant differences between groups were determined at p<0.05 using a Student's T‐test.ResultsThe relative changes in Vm with increased loading by position are shown in Figure 1. Vm decreased by 40% ± 15% (p=0.001) in the HDT position as compared to the supine baseline, showing a predicted, reliable increase in ICP for positional changes. In the seated position, displacement increased slightly from baseline (12% ± 63%, p=0.412) for all subjects across all weight levels, indicating a statistically nonsignificant decrease in ICP. Measurements in the supine position were more consistent, with decreasing Vm (3% ± 3%, p=0.563) for all subjects across all weight levels, indicating a nonsignificant increase in ICP.DiscussionContrary to our hypothesis, measured data showed no significant change in ICP during low level resistance exercise in either the seated or supine positions. Based on these results, resistance exercise may not be the primary contributing factor to the development of SANS in astronauts. This study will form the basis of future investigation into the effects of exercise and ICP in different such as gender, age, and clinical populations. Sensitivity of the CCFP to motion and pulse artifacts will also be addressed to reduce variability between subjects.Support or Funding InformationSupported by NASA grant NNX13AJ12GThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The sweet taste receptor is a heterodimeric G protein‐coupled receptor (GPCR), consisting of the subunits Tas1R2 (T1R2) and Tas1R3 (T1R3). Expression of this receptor has been demonstrated in various tissues throughout the body, including the pancreas, small intestine and adipose tissue. This receptor is thought to play a role in maintaining the body's energy homeostasis, and may potentially be a target in the treatment of metabolic disorders such as diabetes and obesity. Some studies show that the two sweet taste receptor subunits are expressed in unequal quantities in pancreatic β cells and adipocytes, however the impact of this unequal expression on receptor function is not fully understood. This study aims to determine the impact of varying the degree of expression of the two subunits on receptor surface trafficking and downstream signaling pathways. To address this aim, sweet taste receptor‐expressing stable cell lines were generated in AD293 cells by sequential selection of vectors, and in HEK293 TRex cells using bicistronic vectors and the FlpIn system. Receptor expression was characterized through real‐time PCR and biotinylation pull‐down experiments, while receptor signaling was determined in live cells using a genetically encoded Fluorescence Resonance Energy Transfer (FRET) sensor and a Bioluminescence Resonance Energy Transfer (BRET) sensor. Our results show that expression of both receptor subunits is predominantly intracellular, and that co‐expression of both subunits does not improve surface expression. Co‐expression of both subunits was, however, found to be necessary for signaling, as cell lines expressing only one subunit did not show functional responses to aspartame. The magnitude of these functional responses was found to be greatest when subunit expression was closest to 1:1, suggesting that the sweet taste receptor is most efficacious as a 1:1 heterodimer. Cell lines expressing both subunits were found to signal through Gi, as well as undergo extracellular signal‐regulated kinase (ERK) phosphorylation, demonstrating the ability of this receptor to couple to multiple signaling pathways. While some studies using mouse sweet taste receptors have reported Gs signaling at high concentrations of sweeteners, this could not be replicated in this study using human receptors, suggesting that signaling pathways may be species‐specific. Overall, this study shows that co‐expression of both sweet taste receptor subunits is necessary for signaling but not for surface trafficking and that this receptor is most efficacious when both subunits are expressed at equal levels.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

BACKGROUND CONTEXT: Prolonged microgravity exposure is associated with localized low back pain and an elevated risk of post-flight disc herniation. Although the mechanisms by which microgravity impairs the spine are unclear, they should be foundational for developing in-flight countermeasures for maintaining astronaut spine health. Because human spine anatomy has adapted to upright posture on Earth, observations of how spaceflight affects the spine should also provide new and potentially important information on spine biomechanics that benefit the general population. PURPOSE: This study compares quantitative measures of lumbar spine anatomy, health, and biomechanics in astronauts before and after 6 months of microgravity exposure on board the International Space Station (ISS). STUDY DESIGN: This is a prospective longitudinal study. SAMPLE: Six astronaut crewmember volunteers from the National Aeronautics and Space Administration (NASA) with 6-month missions aboard the ISS comprised our study sample. OUTCOME MEASURES: For multifidus and erector spinae at L3-L4, measures include cross-sectional area (CSA), functional cross-sectional area (FCSA), and FCSA/CSA. Other measures include supine lumbar lordosis (L1-S1), active (standing) and passive (lying) flexion-extension range of motion (FE ROM) for each lumbar disc segment, disc water content from T2-weighted intensity, Pfirrmann grade, vertebral end plate pathology, and subject-reported incidence of chronic low back pain or disc injuries at 1-year follow-up. METHODS: 3T magnetic resonance imaging and dynamic fluoroscopy of the lumbar spine were collected for each subject at two time points: approximately 30 days before launch (pre-flight) and 1 day following 6 months spaceflight on the ISS (post-flight). Outcome measures were compared between time points using paired t tests and regression analyses. RESULTS: Supine lumbar lordosis decreased (flattened) by an average of 11% (p=.019). Active FE ROM decreased for the middle three lumbar discs (L2-L3: -22.1%, p=.049; L3-L4: -17.3%, p=.016; L4-L5: -30.3%, p=.004). By contrast, no significant passive FE ROM changes in these discs were observed (p>.05). Disc water content did not differ systematically from pre- to post-flight. Multifidus and erector spinae changed variably between subjects, with five of six subjects experiencing an average decrease 20% for FCSA and 8%-9% for CSA in both muscles. For all subjects, changes in multifidus FCSA strongly correlated with changes in lordosis (r(2)=0.86, p=.008) and active FE ROM at L4-L5 (r(2)=0.94, p=.007). Additionally, changes in multifidus FCSA/CSA correlated with changes in lordosis (r(2)=0.69, p=.03). Although multifidus-associated changes in lordosis and ROM were present among all subjects, only those with severe, pre-flight end plate irregularities (two of six subjects) had post-flight lumbar symptoms (including chronic low back pain or disc herniation). CONCLUSIONS: We observed that multifidus atrophy, rather than intervertebral disc swelling, associated strongly with lumbar flattening and increased stiffness. Because these changes have been previously linked with detrimental spine biomechanics and pain in terrestrial populations, when combined with evidence of pre-flight vertebral end plate insufficiency, they may elevate injury risk for astronauts upon return to gravity loading. Our results also have implications for deconditioned spines on Earth. We anticipate that our results will inform new astronaut countermeasures that target the multifidus muscles, and research on the role of muscular stability in relation to chronic low back pain and disc injury. (C) 2017 Elsevier Inc. All rights reserved.

Purpose To determine the relationship between lamellar layer thickness on ultrashort echo time (UTE) magnetic resonance (MR) images and indentation stiffness of human menisci and to compare quantitative MR imaging values between two groups with normal and abnormally thick lamellar layers. Materials and Methods This was a HIPAA-compliant, institutional review board-approved study. Nine meniscal pieces were obtained from seven donors without gross meniscal pathologic results (mean age, 57.4 years ± 14.5 [standard deviation]). UTE MR imaging and T2, UTE T2*, and UTE T1ρ mapping were performed. The presence of abnormal lamellar layer thickening was determined and thicknesses were measured. Indentation testing was performed. Correlation between the thickness and indentation stiffness was assessed, and mean quantitative MR imaging values were compared between the groups. Results Thirteen normal lamellar layers had mean thickness of 232 μm ± 85 and indentation peak force of 1.37 g ± 0.87. Four abnormally thick lamellar layers showed mean thickness of 353.14 μm ± 98.36 and peak force 0.72 g ± 0.31. In most cases, normal thicknesses showed highly positive correlation with the indentation peak force (r = 0.493-0.912; P < .001 to .05). However, the thickness in two abnormal lamellar layers showed highly negative correlation (r = -0.90, P < .001; and r = -0.23, P = .042) and no significant correlation in the others. T2, UTE T2*, and UTE T1ρ values in abnormally thick lamellar layers were increased compared with values in normal lamellar layers, although only the UTE T2* value showed significant difference (P = .010). Conclusion Variation of lamellar layer thickness in normal human menisci was evident on two-dimensional UTE images. In normal lamellar layers, thickness is highly and positively correlated with surface indentation stiffness. UTE T2* values may be used to differentiate between normal and abnormally thickened lamellar layers. (©) RSNA, 2016.

Study Design. Prospective case series. Objective. Evaluate lumbar paraspinal muscle (PSM) cross-sectional area and intervertebral disc (IVD) height changes induced by a 6-month space mission on the International Space Station. The long-term objective of this project is to promote spine health and prevent spinal injury during space missions and here on Earth. Summary of Background Data. National Aeronautics and Space Administration (NASA) crewmembers have a 4.3 times higher risk of herniated IVDs, compared with the general and military aviator populations. The highest risk occurs during the first year after a mission. Microgravity exposure during long-duration spaceflights results in approximately 5 cm lengthening of body height, spinal pain, and skeletal deconditioning. How the PSMs and IVDs respond during spaceflight is not well described. Methods. Six NASA crewmembers were imaged supine with a 3 Tesla magnetic resonance imaging. Imaging was conducted preflight, immediately postflight, and then 33 to 67 days after landing. Functional cross-sectional area (FCSA) measurements of the PSMs were performed at the L3-4 level. FCSA was measured by grayscale thresholding within the posterior lumbar extensors to isolate lean muscle on T2-weighted scans. IVD heights were measured at the anterior, middle, and posterior sections of all lumbar levels. Repeated measures analysis of variance was used to determine significance at P < 0.05, followed by post-hoc testing. Results. Paraspinal lean muscle mass, as indicated by the FCSA, decreased from 86% of the total PSM cross-sectional area down to 72%, immediately after the mission. Recovery of 68% of the postflight loss occurred during the next 6 weeks, still leaving a significantly lower lean muscle fractional content compared with preflight values. In contrast, lumbar IVD heights were not appreciably different at any time point. Conclusion. The data reveal lumbar spine PSM atrophy after long-duration spaceflight. Some FCSA recovery was seen with 46 days postflight in a terrestrial environment, but it remained incomplete compared with preflight levels. Level of Evidence: 4

Osteoarthritis (OA) in humans is associated with low circulating 25-hydroxyvitamin D3 [25(OH)D3]. In vitamin D replete rats, radiolabeled 24R,25-dihydroxyvitamin D3 [24R,25(OH)2D3] accumulates in articular cartilage following injection of [3H]-25(OH)D3. Previously, we showed that 24R,25(OH)2D3 blocks chondrocyte apoptosis via phospholipase D and p53, suggesting a role for 24R,25(OH)2D3 in maintaining cartilage health. We examined the ability of 24R,25(OH)2D3 to prevent degenerative changes in articular cartilage in an OA-like environment and the potential mechanisms involved. In vitro, rat articular chondrocytes were treated with IL-1β with and without 24R,25(OH)2D3 or 1α,25(OH)2D3. 24R,25(OH)2D3 but not 1α,25(OH)2D3 blocked the effects of IL-1β in a dose-dependent manner, and its effect was partially mediated through the TGF-β1 signaling pathway. In vivo, unilateral anterior cruciate ligament transections were performed in immunocompetent rats followed by intra-articular injections of 24R,25(OH)2D3 or vehicle (t = 0, 7, 14, 21 days). Tissues were harvested on day 28. Joints treated with vehicle had changes typical of OA whereas joints treated with 24R,25(OH)2D3 had less articular cartilage damage and levels of inflammatory mediators. These results indicate that 24R,25(OH)2D3 protects against OA, and suggest that it may be a therapeutic approach for preventing trauma-induced osteoarthritis.

Spaceflight induces headward fluid shifts which may remodel calvarial bone. Previous microCT studies from our lab showed that mice exposed to 15 days of microgravity had increased bone volume density and cortical thickness of calvaria compared to ground control mice. Bone formation is initiated by angiogenesis during normal bone development. VEGF, a key angiogenic molecule, interacts with BMP2 in bone formation and bone healing. Our hypothesis was that bone formation in space mice calvaria is accompanied by vascular changes.Coronal sections from ground control (GC) and spaceflight (SF) mice (n=2) calvaria were stained with eosin and haematoxylin. Unstained sections were processed using a series of dehydration steps with xylene followed by rehydration with ethanol. The slides were then stained with lectin which binds to blood vessels. The vessels were counted manually from 6 sections (10 fields/slide, n=3). BMP‐2, VEGFA and iNOS gene expressions were quantified using real time PCR.Our results document no difference in the number of vessels between GC and SF mice. However the diameter of the vessels (4 vessels/slide) measured using image pro was significantly lower in SF compared to GC mice (34.1 bfl vs 60.3 bfl, p<0.0001, t test). BMP‐2 expression increased 11 fold in SF (n=6, p<0.01, t test). However there was no significant change in VEGFA. Further there was iNOS gene expression in SF (0.3) compared to GC mice (1). These results corroborate that vascular changes observed in the space flight mice maybe partly responsible for increased bone observed in the SF mice. Future studies are required to study the mechanisms of bone‐vascular interaction and bone growth. Supported by Wood Whelan fellowship (JHS), NASA grants NNX09AP11G and NNX13AJ12G (ARH), NSBRI through NASA NCC 9‐58 (BRM).

Spaceflight results in moderate to severe lumbar pain in some astronauts. Moreover, the incidence of herniated nucleus pulposus is about four times greater in US astronauts, as compared to matched controls. In addition, it is unclear if exercise countermeasures during their International Space Station (ISS) missions prevent lumbar paraspinal muscle deconditioning. PURPOSE: To quantify functional paraspinal muscle cross sectional area before, immediately after, and 30-days after 6-month ISS missions. METHODS: To date complete data sets of three astronauts were available for this MRI paraspinal muscle cross sectional area study. Functional cross-sectional area (FCSA) was measured in four lumbar paraspinal muscles (multifidus, erector spinae, quadratus lumborum, and psoas) at lumbar vertebral level 3/4. The FCSA was measured by setting a threshold to isolate altered lean muscle. RESULTS: Long duration spaceflight produced a significant mean 15.1% decrease (p=0.023) in total lumbar paraspinal muscle (multifidus, erector spinae, quadratus lumborum, and psoas) FCSA of the three crewmemebers, as compared to before flight (Table 1). In addition, approximately 63% of this FCSA loss recovered by 30-days after their ISS mission and was not significantly different from before flight (p=0.152). CONCLUSION: These early data indicate that the exercises conducted by these crewmembers did not mitigate decrements in lumbar paraspinal muscle FCSA during spaceflight. However, post-flight recovery activities resulted in a 63% recovery 30-days after their mission. Therefore, these data suggest that spaceflight induced back pain and elevated disc herniation risk may be partly related to reduced dynamic trunk stability linked to atrophied lumbar paraspinal muscles. Supported by NASA grant # NNX13AM89G (to ARH) and NSBRI through NASA NCC 9-58 (to BRM).

Exposure to microgravity during long-duration spaceflights lengthens the spine is associated with a 5-fold greater incidence of herniated nucleus pulposus (HNP), particularly in the cervical region, compared with age-matched ground controls. Concurrent muscle atrophy or deconditioning may also contribute to increased HNP risk. PURPOSE: To evaluate cervical IVD height change and associated paraspinal muscle change following a 6-month International Space Station (ISS) mission and a 30-day post-flight recovery period. METHODS: Cervical spine MRI images were conducted pre-flight, immediate post-flight and 30-to-45 days post-flight recovery of 3 astronauts. IVD heights were measured at the anterior, middle and posterior sections from the upper C2-C3 to lower C7-T1 disc levels. Functional cross-sectional area measurements of the axial cervical paraspinal muscles at the C5-C6 level were performed. The fractional portion of lean muscle area was measured from a standardized region of interest within the posterior cervical extensors. Student-T tests were used to determine significant changes at p<0.05. RESULTS: Cervical IVD heights increased 0.35±0.42mm during the 6-month exposure to microgravity and recovered an average of 0.08±0.37mm over 30 days. The posterior aspect of the IVD heights was significantly decreased during recovery (0.30±0.36mm) while the anterior and middle segments remained swollen (Table 1). An average 9.9±17.8% decrease in cervical lean muscle tissue was measured post flight with a 30-day recovery of 2.2±3.8%. CONCLUSIONS: In the 30 days following ISS missions, there was significant reduction of the posterior cervical IVD heights associated with decreased lean muscle mass of posterior extensors. Supported by NASA grants NNX10AM18G and NNX13AM89G.

BackgroundBack pain and intervertbral disc (IVD) damage are common problems experienced by astronauts. We hypothesize this is from paraspinal muscle deconditioning, ∼5 cm body lengthening from spinal swelling and straightening, and biochemical tissue changes.ObjectiveExamine morphological changes in the lumbar spine induced by spaceflight.DesignProspective, case series clinical study.SettingWe studied crewmembers from the National Aeronautics and Space Administration (NASA).ParticipantsRecruitment from International Space Station NASA/European Space Agency/Canadian Space Agency crewmembers, starting 2011. We enrolled 8 NASA crewmembers. One crewmember completed the study. The others are in various stages of testing.Risk factors AssessmentCrew members were studied before and after a ∼180 day mission in the International Space Station.Main outcome measurementsIn pre-flight and post-flight studies of the lumbar spine, evaluate: 1) degenerative changes using MRI, 2) compressibility using an upright MRI backpack loading protocol, 3) spinal kinematics with X-ray videography, 4) visual analog scale pain.ResultsComparing pre-flight and post- flight data, there were 1) increased lumbar IVD heights in the supine position, 2) increased lumbar IVD compressibility in the upright position, 3) decreased flexibility, and 4) increased low back pain post-flight.Figure 1Spinal kinematics (angles in degrees) during flexion/extension. Pre-flight degenerate disks had less motion. Post-flight, all disks had less motion.ConclusionsThe data support the idea that decreased gravitational forces on the IVDs, during prolonged microgravity, increases their water content but decreases proteoglycan. This increases disk degeneration risk on Earth. We have a sample size of one for complete Pre- and Post-Flight testing. It's difficult to make conclusions with this preliminary data. However, the acquired images are very high quality and provide confidence for future tests. The next crewmember returns to Earth for final testing November, 2013. Testing of 4 crewmembers and ongoing recruitment are underway.

OBJECTIVE:To implement high-resolution morphologic and quantitative magnetic resonance imaging (MRI) of the temporomandibular joint (TMJ) using ultrashort time-to-echo (UTE) techniques in cadavers and volunteers.METHODS:This study was approved by the institutional review board. TMJs of cadavers and volunteers were imaged on a 3-T MR system. High-resolution morphologic and quantitative sequences using conventional and UTE techniques were performed in cadaveric TMJs. Morphologic and UTE quantitative sequences were performed in asymptomatic and symptomatic volunteers.RESULTS:Morphologic evaluation demonstrated the TMJ structures in open- and closed-mouth position. UTE techniques facilitated the visualization of the disc and fibrocartilage. Quantitative UTE MRI was successfully performed ex vivo and in vivo, reflecting the degree of degeneration. There was a difference in the mean UTE T2* values between asymptomatic and symptomatic volunteers.CONCLUSIONS:MRI evaluation of the TMJ using UTE techniques allows characterization of the internal structure and quantification of the MR properties of the disc. Quantitative UTE MRI can be performed in vivo with short scan times.

Magnetization transfer (MT) imaging is one way to indirectly assess pools of protons with fast transverse relaxation. However, conventional MT imaging sequences are not applicable to short T2 tissues such as cortical bone. Ultrashort echo time (UTE) sequences with TE values as low as 8 µs can detect signals from different water components in cortical bone. In this study we aim to evaluate two‐dimensional UTE‐MT imaging of cortical bone and its application in assessing cortical bone porosity as measured by micro‐computed tomography (μCT) and biomechanical properties. In total, 38 human cadaveric distal femur and proximal tibia bones were sectioned to produce 122 rectangular pieces of cortical bone for quantitative UTE‐MT MR imaging, μCT, and biomechanical testing. Off‐resonance saturation ratios (OSRs) with a series of MT pulse frequency offsets (Δf) were calculated and compared with porosity assessed with μCT, as well as elastic (modulus, yield stress, and strain) and failure (ultimate stress, failure strain, and energy) properties, using Pearson correlation and linear regression. A moderately strong negative correlation was observed between OSR and μCT porosity (R2 = 0.46–0.51), while a moderate positive correlation was observed between OSR and yield stress (R2 = 0.25–0.30) and failure stress (R2 = 0.31–0.35), and a weak positive correlation (R2 = 0.09–0.12) between OSR and Young's modulus at all off‐resonance saturation frequencies. OSR determined with the UTE‐MT sequence provides quantitative information on cortical bone and is sensitive to μCT porosity and biomechanical function. Copyright © 2015 John Wiley & Sons, Ltd.

We conducted this study to evaluate the effect of radiofrequency (RF) stimulation with suture repair on the healing of tears in the meniscal white-white zone. Fifty-four New Zealand white rabbits underwent surgically induced meniscal injuries within the white-white region. RF was applied using a 0.8-mm TOPAZ MicroDebrider RF wand (ArthroCare) at level 4 for 500 milliseconds. Rabbits were sacrificed at 28 and 84 days for gross and histologic analysis by 3 blinded observers and at 9, 28, and 84 days for biochemical examination. Biochemical analyses included evaluation of cell proliferation (3H-thymidine), as well as mitogenic (IGF-1, bFGF) and angiogenic (VEGF, αV) factors. Of specimens repaired with RF combined with suture, 19 (58%) showed a degree of gross morphologic and histologic healing. No significant healing was seen in specimens with either no repair or repair with suture alone. We observed a 40% increase in cellular proliferation when RF supplementation was used (P<.05). With regards to mitogenic and angiogenic markers (IGF-1, bFGF, VEGF, and αV), there was a significant increase in groups treated with RF at 9 and 28 days (P>0.05). RF supplementation of avascular zone meniscal repairs may lead to an increased healing response.

This review gives an overview of chiral separation principles and their application in enantioselective nano/micro high performance liquid chromatography (n/μ-HPLC) using chiral monolith. In particular, developments in silica and polymer chiral monolithic stationary phases are presented. The preparation and applications of chiral monoliths, the basic chiral separation principles and the mechanisms are discussed.

Plasmid DNA (pDNA)-based vaccines offer more rapid avenues for development and production if compared to those of conventional virus-based vaccines. They do not rely on time- or labour-intensive cell culture processes and allow greater flexibility in shipping and storage. Stimulating antibodies and cell-mediated components of the immune system are considered as some of the major advantages associated with the use of pDNA vaccines. This review summarizes the current trends in the purification of pDNA vaccines for practical and analytical applications. Special attention is paid to chromatographic techniques aimed at reducing the steps of final purification, post primary isolation and intermediate recovery, in order to reduce the number of steps necessary to reach a purified end product from the crude plasmid.

Clinical studies have shown inconsistent healing with subjective improvement after use of platelet-rich plasma (PRP) for tendinosis and partial tendon tears. We conducted a study to assess changes after injecting PRP into an intact rabbit patellar tendon (PT) model. In the study group (n = 10), an incision was made over the PT and PRP was injected into multiple sites on the PT. The control group (n = 8) was injected with saline. PTs were harvested 7 and 28 days after injection. Hematoxylin-eosin staining showed hypercellularity in the PRP group at 7 days, but the effect was not as marked at 28 days. At 7 days, polarized microscopy showed increased crimp density of collagen in the PRP group, compared with the control group, demonstrating up-regulation in collagen matrix. Cellular proliferation measured by tritiated thymidine was also significantly increased (P = .02) in the PRP group, compared with the control group, but the difference was not as significant at 28 days. At 7 and 28 days, there were no significant changes in basic fibroblast growth factor, insulin-like growth factor, vascular endothelial growth factor, or platelet-derived growth factor with 2B chains. Injection of PRP into rabbit PT enhances collagen remodeling and hypercellularity with increased metabolic activity, which could have a positive effect on healing.