Biology and augmentation of tendon-bone insertion repair

Surgical reattachment of tendon and bone such as in rotator cuff repair, patellar-patella tendon repair and anterior cruciate ligament (ACL) reconstruction often fails due to the failure of regeneration of the specialized tissue ("enthesis") which connects tendon to bone. Tendon-to-bone healing taking place between inhomogenous tissues is a slow process compared to healing within homogenous tissue, such as tendon to tendon or bone to bone healing. Therefore special attention must be paid to augment tendon to bone insertion (TBI) healing. Apart from surgical fixation, biological and biophysical interventions have been studied aiming at regeneration of TBI healing complex, especially the regeneration of interpositioned fibrocartilage and new bone at the healing junction. This paper described the biology and the factors influencing TBI healing using patella-patellar tendon (PPT) healing and tendon graft to bone tunnel healing in ACL reconstruction as examples. Recent development in the improvement of TBI healing and directions for future studies were also reviewed and discussed.

Symmetry energy of dilute warm nuclear matter

The symmetry energy of nuclear matter is a fundamental ingredient in the investigation of exotic nuclei, heavy-ion collisions, and astrophysical phenomena. New data from heavy-ion collisions can be used to extract the free symmetry energy and the internal symmetry energy at subsaturation densities and temperatures below 10 MeV. Conventional theoretical calculations of the symmetry energy based on mean-field approaches fail to give the correct low-temperature, low-density limit that is governed by correlations, in particular, by the appearance of bound states. A recently developed quantum-statistical approach that takes the formation of clusters into account predicts symmetry energies that are in very good agreement with the experimental data. A consistent description of the symmetry energy is given that joins the correct low-density limit with quasiparticle approaches valid near the saturation density.

Pulmonary hypertension is ameliorated in mice deficient in thrombin-activatable fibrinolysis inhibitor

BACKGROUND

The fibrinolytic system has been implicated in the pathogenesis of pulmonary hypertension (PH). Thrombin-activatable fibrinolysis inhibitor (TAFI) inhibits fibrinolysis and therefore its absence would be expected to increase fibrinolysis and ameliorate PH.

OBJECTIVE

The objective of the present study was to evaluate the effect of TAFI deficiency on pulmonary hypertension in the mouse.

METHODS AND RESULTS

PH was induced in C57/Bl6 wild-type (WT) or TAFI-deficient (KO) mice by weekly subcutaneous treatment with 600 mg kg(-1) monocrotaline (MCT) for 8 weeks. PH was inferred from right heart hypertrophy measured using the ratio of right ventricle-to-left ventricle-plus-septum weight [RV/(LV+S)]. Pulmonary vascular remodeling was analyzed by morphometry. TAFI-deficient MCT-treated and wild-type MCT-treated mice suffered similar weight loss. TAFI-deficient MCT-treated mice had reduced levels of total protein and tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), transforming growth factor-beta (TGF-beta) and monocyte chemoattractant protein-1 (MCP-1) in bronchial alveolar lavage compared with wild-type MCT-treated mice. The ratio of RV to (LV+S) weight was significantly higher in WT/MCT than in KO/MCT mice. The pulmonary artery wall area and vascular stenosis were both greater in MCT-treated WT mice compared with MCT-treated TAFI-deficient mice.

CONCLUSIONS

TAFI-deficient MCT-treated mice had less pulmonary hypertension, vascular remodeling and reduced levels of cytokines compared with MCT-treated WT animals, possibly as a result of reduced coagulation activation.

Association of Notch signaling pathway expression in liposarcomas with outcome, and targeting with gamma-secretase inhibitors

10526

Background: The Notch pathway directs normal fat cell development, but its aberrant activation may promote the development of sarcomas. The expression of the Notch pathway in liposarcoma (LPS), however, is unknown. We examined Notch signaling components in LPS's and suppressed Notch activation with drug targeting in LPS cell lines. Methods: RNA was isolated from 18 normal fat and 140 LPS tissue samples from five LPS subtypes: well-differentiated (33%), de-differentiated DD (25%), myxoid (12%), round cell (6%), and pleomorphic (13%), and were hybridized to Affymetrix U133A arrays. Microarray data were normalized with the RMA method. Correlation analysis identified genes expressed between sample classes, using Empirical Bayes t-test, and genes associated with survival, using Cox regression. The Notch pathway in two LPS lines, DDLS and LS141, was suppressed with a novel gamma-secretase inhibitor (GSI) or with siRNA to Notch receptors. Viability was assessed by colony formation, apoptosis by DAPI staining, and Notch expression by immunoblotting. Results: Expression of Notch-3 and its targets, Hes-1, Hey-1, and survivin, was increased in LPS subtypes, compared to fat tissue (p<0.001). Inhibition of Notch signaling with GSI's or siRNA to Notch-1 suppressed the viability of both DD LPS lines (p<0.05), inducing a G1/S arrest followed by apoptosis. Transfection of siRNA to each Notch receptor, especially Notch-3, also suppressed the viability of DD LPS's (p<0.05). Expression of Notch-3 (p=0.027, HR=2.64), Notch-4 (p=0.026, HR=2.70), the ligand JAG-2 (p=0.049, HR=2.32), and Hey-1 (p=0.001, HR=4.25) was associated with reduced distant recurrence free survival in patients with DD LPS's. Expression of the negative Notch regulator Fbxw7 was associated with improved overall survival in patients with LPS (p=0.008, HR=-1.42). Conclusions: Elements of the Notch pathway (receptors, ligands, targets, and modifiers) are overexpressed in LPS's compared to normal fat tissue and associate with outcome. Suppression of Notch signaling decreased DD LPS cell line viability and induced apoptosis. Notch inhibition may represent a new therapeutic strategy for patients with LPS's and deserves further validation in a clinical trial.

No significant financial relationships to disclose.

The time-dependent structural and magnetic properties of CoPt nanowire arrays by AC electrodeposition

High areal density CoPt alloy nanowire arrays have been fabricated in anodic aluminum oxide templates by AC electrodeposition. We demonstrate that the AC electrodeposition time in this technique is a very important parameter for the microstructure and magnetic properties of the nanowire arrays. It is found that the mean length of the nanowire arrays, for given electrodeposition conditions, may reach a maximum value at a certain electrodeposition time. As nanowire arrays reach their maximum length, magnetic switching jump in hysteresis loops is observed and it becomes more remarkable with further increasing the deposition time. The corresponding origins of these properties are discussed.

Noncontact evaluation of articular cartilage degeneration using a novel ultrasound water jet indentation system

We previously reported a noncontact ultrasound water jet indentation system for measuring and mapping tissue mechanical properties. The key idea was to utilize a water jet as an indenter as well as the coupling medium for high-frequency ultrasound. In this paper, the system was employed to assess articular cartilage degeneration, using stiffness ratio as an indicator of the mechanical properties of samples. Both the mechanical and acoustical properties of intact and degenerated bovine patellar articular cartilage (n = 8) were obtained in situ. It was found that the stiffness ratio was reduced by 44 +/- 17% after the articular cartilage was treated by 0.25% trypsin at 37 degrees C for 4 h while no significant difference in thickness was observed between the intact and degenerated samples. A significant decrease of 36 +/- 20% in the peak-to-peak amplitude of ultrasound echoes reflected from the cartilage surface was also found for the cartilage samples treated by trypsin. The results also showed that the stiffness obtained with the new method highly correlated with that measured using a standard mechanical testing protocol. A good reproducibility of the measurements was demonstrated. The present results showed that the ultrasound water jet indentation system may provide a potential tool for the non-destructive evaluation of articular cartilage degeneration by simultaneously obtaining mechanical properties, acoustical properties, and thickness data.

Quantum nature of a nuclear phase transition

At finite temperatures and low densities, nuclei may undergo a phase change similar to a classical liquid-gas phase transition. Temperature is the control parameter while density and pressure are the conjugate variables. In the nucleus the difference between the proton and neutron concentrations acts as an additional order parameter, for which the symmetry potential is the conjugate variable. We present experimental results which reveal the N/Z dependence of the phase transition and discuss possible implications of these observations in terms of the Landau free energy description of critical phenomena.

A delayed bone-tendon junction healing model established for potential treatment of related sports injuries

BACKGROUND

Animal models for the study of tendinopathy and bone-tendon (B-T) junction repair have been established in the past for sports medicine research. As healing at the B-T junction is difficult and sometimes delayed, establishing a delayed B-T healing experimental model is therefore essential to study the efficacy of potential biophysical and biological interventions for treatment of B-T junction healing.

OBJECTIVE

To test the hypothesis that a delay in B-T healing could be modelled by shielding the B-T healing interface for the initial few weeks.

METHODS

Using an established partial patellectomy model in rabbits, the B-T healing interface was shielded with a latex slice for the first 4 postoperative weeks in mature female rabbits. The characteristics of delay in B-T repair (n = 10) compared with controls (n = 10) were evaluated at 8 and 12 postoperative weeks.

RESULTS

Radiology showed consistent delay in osteogenesis at the healing interface in all samples in the delayed healing group; growth of new bone was only 25.8% and 50.1% of that in the control group at weeks 8 and 12, respectively. Bone mineral density was 56.0% lower in the delayed healing group at week 8, but this difference diminished at week 12. The quality of B-T healing was poor in the delayed healing group, with 22.9% and 24.2% lower failure load than the control group at weeks 8 and 12, respectively. The healing quality was also reflected by histological findings.

CONCLUSIONS

A delayed B-T healing experimental model was established for the first time for future sports medicine research.

Altered osmotic swelling behavior of proteoglycan-depleted bovine articular cartilage using high frequency ultrasound

Swelling behavior is an electrochemical mechanical property of articular cartilage. It plays an important role in weight bearing and joint lubrication. In this study, the altered transient and inhomogeneous swelling behavior of the degenerated articular cartilage was observed and quantified in situ using ultrasound. Three groups of bovine patellar articular cartilage samples (n = 10 x 3) were obtained and digested by trypsin for 10, 20 and 30 min respectively to mimic different levels of degeneration. The osmotic-free shrinkage and swelling behavior induced by changing the concentration of the bathing saline solution from 0.15 M to 2 M and then back to 0.15 M were characterized using high-frequency ultrasound (central frequency = 35 MHz) before and after digestion. It was found that the degenerated cartilage specimens showed a weaker shrinkage-swelling behavior compared with the normal cartilage samples. However, no significant differences in the peak shrinkage or swelling strains were observed between different groups. The absolute values of the peak shrinkage strain significantly (p < 0.05) decreased by 45.4%, 42.1% and 50.6% respectively after the trypsin digestion for 10, 20 and 30 min, but such significance was not demonstrated for the peak swelling strains. Due to the potential alterations in the collagen-PG matrix during trypsin digestion, the correlation between the swelling strain and the shrinkage strain of the degenerated samples changed slightly in comparison with the normal samples. The proposed ultrasound method has been successfully used to measure the transient and inhomogeneous swelling behavior of the degenerated articular cartilage and has the potential for the characterization of osteoarthritis.

Protective role of thrombin activatable fibrinolysis inhibitor in obstructive nephropathy-associated tubulointerstitial fibrosis

BACKGROUND

Thrombin-activatable fibrinolysis inhibitor (TAFI) has been reported to affect wound healing and fibrotic processes, but its role in renal tubulointerstitial fibrosis remains unknown.

OBJECTIVE

To study its potential role, we compared TAFI-deficient and wild-type mice for the degree of renal fibrosis caused by unilateral ureteral obstruction (UUO).

METHODS

The grade of tubulointerstitial fibrosis, the activity of plasmin, MMP-2 and MMP-9 were evaluated on days 4 and 9 after UUO.

RESULTS

The renal content of hydroxyproline and the activity of plasmin, MMP-2 and MMP-9 were significantly increased in kidneys with UUO from TAFI-deficient mice compared with those from wild-type mice. These differences disappeared when animals with UUO from both groups were treated with the plasmin inhibitor tranexamic acid. The renal concentrations of fibrogenic cytokines were also significantly elevated in kidneys with UUO from TAFI-deficient mice compared with those from wild-type mice.

CONCLUSION

The results of this study suggest that increased renal activity of plasmin in TAFI-deficient mice causes increased renal interstitial fibrosis in obstructive nephropathy.

An assessment of the role of ethylene in mediating lettuce (Lactuca sativa) root growth at high temperatures

Growth of temperate lettuce (Lactuca sativa) plants aeroponically in tropical greenhouses under ambient root-zone temperatures (A-RZTs) exposes roots to temperatures of up to 40 degrees C during the middle of the day, and severely limits root and shoot growth. The role of ethylene in inhibiting growth was investigated with just-germinated (24-h-old) seedlings in vitro, and 10-d-old plants grown aeroponically. Compared with seedlings maintained at 20 degrees C, root elongation in vitro was inhibited by 39% and root diameter increased by 25% under a temperature regime (38 degrees C/24 degrees C for 7 h/17 h) that simulated A-RZT in the greenhouse. The effects on root elongation were partially alleviated by supplying the ethylene biosynthesis inhibitors aminooxyacetic acid (100-500 microM) or aminoisobutyric acid (5-100 microM) to the seedlings. Application of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid to seedlings grown at 20 degrees C mimicked the high temperature effects on root elongation (1 microM) and root diameter (1 mM). Compared with plants grown at a constant 20 degrees C root-zone temperature, A-RZT plants showed decreased stomatal conductance, leaf relative water content, photosynthetic CO(2) assimilation, shoot and root biomass, total root length, the number of root tips, and root surface area, but increased average root diameter. Addition of 10 microM ACC to the nutrient solution of plants grown at a constant 20 degrees C root-zone temperature mimicked the effects of A-RZT on these parameters but did not influence relative water content. Addition of 30 microM aminoisobutyric acid or 100 microM aminooxyacetic acid to the nutrient solution of A-RZT plants increased stomatal conductance and relative water content and decreased average root diameter, but had no effect on other root parameters or root and shoot biomass or photosynthetic CO(2) assimilation. Although ethylene is important in regulating root morphology and elongation at A-RZT, the failure of ethylene biosynthesis inhibitors to influence shoot carbon gain limits their use in ameliorating the growth inhibition induced by A-RZT.

Postoperative Programmed Muscle Tension Augmented Osteotendinous Junction Repair

The postoperative programmed muscle tension induced by functional electrical stimulation (FES) was evaluated for its potential efficacy on acceleration of osteotendinous junction healing using an established partial patellectomy model in rabbits. After immobilization of the operated knee for 6 weeks, daily FES was applied to quadriceps muscles for 30 minutes per day and 5 days per week for 6 weeks in the treatment group and compared with the non-treatment control group at postoperative week 12 and 18, radiologically, histologically and biomechanically. Results showed that FES-induced muscle tension significantly increased new bone formation, bone mineral density, and fibrocartilage zone restoration in the osteotendinous healing interface. The failure load and ultimate strength of the repairing osteotendinous complex were also improved significantly with healing over time. In conclusion, the postoperative programmed FES-induced muscle tension was favorable for acceleration of osteotendinous junction repair and therefore recommended for clinical trails in orthopedic sports medicine and rehabilitation.

Five-year survival analysis of liver metastasis of colorectal cancer after hepatic resection

14571

Background: To evaluate the relation between hepatic resecion and survival rate of liver metastasis of colorectal cancer ( LMCC). Methods: Use retrograde case analysis method, 133 cases of LMCC received hepatic resection from 1/1/2000 to 31/12/2005 were included,with attention to the relation between hepatic resection and survival rate. Results: There were 133 cases underwent curative hepatic resection in all 470 LMCC cases, of which 30 cases (30/196,15.3%) in synchronous liver metastasis (SLM) group and 103 cases (103/274,37.6%) in metachronous liver metastasis (MLM) group, P<0.01. Mortality rate related to operation was 3.3%(1/30) in SLM and 1.9%(2/103) in MLM(P<0.05). Until 31/6/2006, all 133 cases were followed-up, 1,3,5 years survival rate and median survival time of SLM (81.0%, 40.3%, 16.5%, 22 months) is similar to that of MLM (88.2%, 49.1%, 31.7%, 25 months, P > 0.05), but the recurrence rate is higher(36.7% vs 20.4%,P=0.03). Compared to 49 cases whose liver metastases focus can be resected but chosen non- operative therapy, 1, 3, 5 years survival rate of 133 resected cases is higher (55.6%, 11.0%, 0 vs 86.2%, 39.2%, 29.4%, P=0.0034). In SLM, 22 cases received I stage resection of the primary colorectal tumor and liver metastasis and 8 cases received liver metastasis resection after the primary surgery (II stage operation). 1, 2, 3 years survival are 90.0% vs 87.5%(P > 0.05),61.4% vs 55.3%(P > 0.05)and 35.4% vs 30.0%(P > 0.05) and the median survival time is 28 months vs 26months(P > 0.05).COX multivariate analysis was used to analyze the prognositic factors. Incision margin =1cm(β=-0.8351,P=0.0363)and reoperation after recurrence(β=- 0.9428,P=0.0411)were protective survival factors, and postoperation recurrence (β=0.6471,P=0.0226) was survival risk factor. Conclusions: Curative hepatic resection is the first choice of liver metastasis of colorectal cancer and can improve survival.

No significant financial relationships to disclose.

Evaluation of the feasibility of expression microarray analysis in endoscopically obtained biopsies of gastric carcinoma and their clinical applicability

21164

Background: The feasibility of extracting high quality RNA for expression microarray analysis from endoscopic biopsy in gastric carcinoma has not been previously established. Methods: Patients with histologically confirmed locally advanced gastric or gastroesophageal junction adenocarcinoma were screened for enrollment in an NCI-sponsored trial of neoadjuvant irinotecan and cisplatin chemotherapy (NC1–5917). All patients underwent a repeat endoscopic biopsy for the procurement of fresh tumor tissue. Gross microdissection was performed to enrich the sample to at least 80% malignancy. RNA was isolated from the tumor specimens using RNeasy columns (Qiagen) and its quality verified by RNA 6000 NanoAssay and Bioanalyzer 2100 (Agilent). Gene expression profiling was performed on Human Genome U133A GeneChip (Affymetrix) which contained 22,215 oligonucleotide-base probe-sets. Differential gene expression profiles for Lauren's classification were assessed using empirical Bayes t test, a threshold p < 0.001 was considered statistically significant. Results: Of 36 patients with previous biopsy confirmed gastric cancer, repeat endoscopic biopsy identified carcinoma in 28 patients (78%, 95%CI 61–90%). Adequate RNA for microarray analysis was obtained from 21 patients-representing 58% of those who presented for the procedure and 75% in whom endoscopic biopsies confirmed malignancy. This yield improved with increasing number of samples taken. Lauren's classification was available on 26 patients who underwent resection. From the total 54,613 gene probe-sets on the arrays, comparison of the expression profiles of diffuse-type and intestinal-type identified 167 genes that were differentially expressed. Diffuse gastric cancer demonstrated altered expression of genes related to cell-matrix interaction whereas intestinal gastric cancer expression analysis showed enhancement of cell growth. Conclusions: Endoscopic biopsy for expression analysis of gastric cancer is feasible with increasing yield with each core taken. Expression analysis at the time of endoscopic biopsy can differentiate Lauren's histology, a characteristic not routinely evaluable by pathologic review.

No significant financial relationships to disclose.

Analysis of toxicity in a phase II study of sorafenib in soft tissue sarcoma (STS)

10061

Background: Sorafenib (BAY 43–9006) is an oral multi-targeted kinase inhibitor. Sorafenib causes dermatologic toxicity and hypertension, although the mechanisms are poorly understood. We observed significant toxicity requiring dose reductions in our phase II study of sorafenib in STS. Methods: 120 patients (40 M, 80 F; median age, 55 years) were treated between 10/05 and 12/06; accrual continues. All patients initially received sorafenib 400 mg BID. 118/120 registered patients were evaluable for toxicity. Clinical and laboratory variables were analyzed for association with dose reduction, using Kruskal-Wallis rank sum test for continuous variables and Fisher exact test for categorical variables. Variables significant at the p=0.05 level were further analyzed with a multivariate logistic regression model for their effects on dose reduction. Results: 53% of patients (63/118) required dose reductions, 53/63 for grade 2 or greater skin toxicity. Most common grade 3–4 drug-related toxicities included lymphopenia (14%), rash (12%), and hand-foot skin reaction (10%). Sex, height, weight, BSA and serum creatinine (Cr) were significantly associated with dose reduction by univariate analysis. Adjusting for sex and/or low serum Cr, BSA was not significantly associated with dose reduction. Sex and low serum Cr were borderline statistically significant predictors of dose reductions when both variables were included in a multivariate model. Only female sex remained a significant predictor when eliminating one outlier with BSA 2.83 (p=0.04). Conclusions: Female gender appears associated with skin toxicity, requiring dose reductions. Based on this multivariate analysis, a starting dose of 400 mg oral daily in women may limit side effects. Correlation with trough serum sorafenib levels is pending. This study is funded in part by NCI Grant P01-CA47179.

No significant financial relationships to disclose.

Epimedium-derived phytoestrogen exert beneficial effect on preventing steroid-associated osteonecrosis in rabbits with inhibition of both thrombosis and lipid-deposition

OBJECTIVES

This study tested the effect of Epimedium-derived phytoestrogen (PE) on preventing steroid-associated osteonecrosis (ON) in rabbit model.

METHODS

Thirty 28-week-old male New-Zealand white rabbits were divided into control group (CON; n=14) and PE group (PE; n=16; 5 mg/kg body weight/day) after receiving an established inductive protocol for inducing steroid-associated ON. Before and after inductive protocol, Dynamic-MRI was employed on bilateral femora for local intra-osseous perfusion, blood samples were examined for coagulation, fibrinolysis and lipid-transportation, and marrow samples were quantified for adipogenesis-gene mRNA expression. Six weeks later, bilateral femora were dissected for Micro-CT-based micro-angiography, and then ON lesion, intravascular thrombosis and extravascular fat-cell-size were examined histopathologically.

RESULTS

The incidence of ON in the PE group (31%) was significantly lower than that in the CON group (93%). Compared to the CON group, local intra-osseous perfusion was maintained in the PE group. Blocked trunk vessels were seldom found in micro-angiography of the PE-treated rabbits. Thrombosis incidence and fat-cell-size were both significantly lower in the PE group than those in the CON group. During the early period after induction, indicator of coagulation, fibrinolysis, lipid-transportation and adipogenesis-gene expression were found with significantly changing pattern in the PE group compared to the CON group.

CONCLUSION

PE was able to exert beneficial effect on preventing steroid-associated ON in rabbits with inhibition of both thrombosis and lipid deposition.

Motor imagery classification by means of source analysis methods

We report our investigation of classification of imagined left and right hand movements by applying source analysis methods. Independent component analysis (ICA) is used as a spatio-temporal filter, then equivalent dipole analysis and cortical current density imaging methods are applied to reconstruct equivalent sources, to aid classification of motor imagery tasks in a human subject. The classification was considered correct if the equivalent source was found over the motor cortex in the corresponding hemisphere. A classification rate of about 80% was achieved in the human subject studied using both the equivalent dipole analysis and the cortical current density imaging analysis.

Vaccinia virus preferentially infects and controls human and murine ovarian tumors in mice

Vaccinia virus has been shown to efficiently infect tumor cells. Therefore, vaccinia virus represents a potentially safe and effective antitumor agent against ovarian cancer. Here, we assessed the ability of vaccinia virus to preferentially infect and control both human and murine ovarian tumors in vivo. We used the non-invasive luminescence imaging system to monitor the infection and suppression of ovarian tumors by vaccinia in live mice. Our data indicated that vaccinia was able to effectively infect and kill both human and murine ovarian tumors. Vaccinia virus administered to mice intraperitoneally was specifically targeted to the murine or human ovarian tumors and led to antitumor responses. These findings suggest that vaccinia virus is capable of selectively targeting and controlling ovarian tumors. Thus, intraperitoneal injection with vaccinia virus may provide a potentially effective strategy for treating advanced-stage ovarian cancers.

Supplementation-time dependence of growth factors in promoting tendon healing

Growth factors potentially promote tendon healing. Understanding the right time to administer growth factors and the dosage of growth factors are prerequisites for designing effective cytokine therapy. We investigated the supplementation-time dependence of the effects of platelet-derived growth factor isoform B at various dosages on tendon healing, and the temporal responsiveness of healing tendon toward platelet-derived growth factor. Platelet-derived growth factor isoform B at various dosages (0, 10, 100, or 1000 ng) was delivered into the gap wound of rat patellar tendons via microsyringe injection on Day 3 or Day 7 after injury. Tendon specimens were harvested on Day 14 for measurement of cell proliferation, pyridinoline content, and mechanical properties. We found increased proliferative response only when the growth factor was supplemented on Day 3 after injury, whereas supplementation on Day 7 resulted in greater peak load, cross-sectional area, and pyridinoline content. The ultimate stress did not change. Our findings suggest supplementation of platelet-derived growth factor isoform B at Day 7 benefits the mechanical properties and maturation of healing tendons. We also found platelet-derived growth factor receptor beta expressing cells at the remodeling site as much as 6 months after injury, suggesting healing tendon also may be responsive to long-term delivery of platelet-derived growth factor.

Flavonoids derived from herbal Epimedium Brevicornum Maxim prevent OVX-induced osteoporosis in rats independent of its enhancement in intestinal calcium absorption

AIM

Factorial design was used to test our hypothesis whether a group of flavonoids (FE) derived from herbal Epimedium Brevicornum Maxim exerted its preventive effects on estrogen-deficiency-induced osteoporosis mainly through an enhancement in intestinal calcium absorption.

MATERIALS AND METHODS

Forty-five 12-month-old female Wistar rats were used and randomly assigned into sham-operated group and four ovariectomy (OVX) subgroups, i.e. OVX with vehicle (OVX group), OVX with FE (FE group), OVX with calcium supplement (CS group), and OVX with FE and CS (FE + CS group). Daily oral administration of FE (10 mg/kg/day) and/or CS (56 mg/kg/day) started on day 4 after OVX for 12 weeks. Before sacrificing the animals, urine and serum samples were collected for assaying indicators related to intestinal calcium absorption, regulator for calcium homeostasis, and markers of bone turnover. The left proximal femur was dissected for evaluation of the primary end-point (failure force), the second end-points (pQCT-quantified densitometry, geometry, and micro-CT-quantified 3-D trabecula micro-architecture), and pQCT-defined cross-sectional envelope.

RESULTS

FE was found to be able to prevent OVX-induced reduction in failure force as well as the above second end-points, without resulting in an increased uterus weight. CS had no preventive effect on OVX-induced reduction in failure force. Two-way factorial interaction analysis between FE and CS showed that the un-enhanced suppression of parathyroid hormone for calcium homeostasis did not provide link between the enhanced intestinal calcium absorption and the enhanced inhibition of bone resorption in the present study. Furthermore, the discrepancies between the enhanced intestinal calcium absorption and the un-enhanced end-point measures as well as anabolic effect were also revealed by the interaction analysis.

CONCLUSION

The present study suggested that FE inhibited bone resorption, stimulated bone formation, and accordingly prevented osteoporosis without hyperplastic effect on uterus in the OVX rat model, which was however independent of an enhancement in intestinal calcium absorption.

Potent regulation of microglia-derived oxidative stress and dopaminergic neuron survival: substance P vs. dynorphin

Unregulated microglial activation has been implicated as a pivotal factor contributing to Parkinson's disease. Using mesencephalic neuron-glia cultures, we address the novel possibility that peptides endogenous to the substantia nigra (SN), substance P and dynorphin (10(-13)-10(-14) M), are opposing mediators of microglial activation and consequent DA neurotoxicity. Here, we identify that substance P (10(-13)-10(-14) M) is selectively toxic to DA neurons in a microglia-dependent manner. Mechanistically, substance P (10(-13)-10(-14) M) activated microglial NADPH oxidase to produce extracellular superoxide and intracellular reactive oxygen species (ROS). Neuron-glia cultures from mice lacking a functional NADPH oxidase complex (PHOX-/-) were insensitive to substance P (10(-13)-10(-14) M) -induced loss of DA neuron function. Mixed glia cultures from (PHOX-/-) mice failed to show a significant increase in intracellular ROS in response to substance P compared with control cultures (PHOX+/+). Further, dynorphin (10(-14) M) inhibited substance P (10(-13) M) -induced loss of [3H] DA uptake. Here we demonstrate a tightly regulated mechanism governing microglia-derived oxidative stress, where the neuropeptide balance of dynorphin and substance P is critical to DA neuron survival.

Lower degree of mineralization found in cortical bone of adolescent idiopathic scoliosis (AIS)

A lowered bone mineral density (BMD) was observed in trabecular bone in a significant number of AIS patients. The present study aims at investigating whether lower BMD is a systemic phenomenon, which would also be present in the cortical component of long bone.

SUBJECTS AND METHODS

78 AIS girls (age:15-18y.o) with either moderate (Cobb: 20-40) or severe (Cobb: >40) curve and 44 age-matched controls were recruited. The BMD of the distal region and the mid-shaft of radius were measured with a multi-layer peripheral quantitative computed tomography (pQCT). The trabecular bone and cortical bone BMD and the morphology of mid-shaft were compared.

RESULTS

Both trabecular and cortical BMD in severe AIS group was significantly lower than the control by 8.7% and 1.7% (p<0.05 for both), respectively. However, the cortical bone area of the mid-shaft did not show any differences from the normal control subjects.

DISCUSSION

This study demonstrates a systemic low BMD including the cortical bone. It is suggested that AIS girls may have disturbance in mineralization and ossification during peripubertal growth.

Genetic association study of insulin-like growth factor-I (IGF-I) gene with curve severity and osteopenia in adolescent idiopathic scoliosis

IGF-I has a pivotal role in bone growth and could be one of the putative disease-modifier genes in AIS. Two SNPs in IGF-I gene promoter region were studied for any association with occurrence of AIS and for their effect on the curve severity among AIS.

METHODS

506 AIS girls (Cobb>20 degrees) and 227 age-matched Chinese girls were recruited. The spine (L2-L4) and hip BMD of the subjects were measured by DXA. A subgroup of AIS patients (N=340) who were followed-up to skeletal maturity and the maximum Cobb's angle was recorded. Two SNPs were genotyped by PCR-RFLP (rs5742612 and rs2288377). The chi-square test and one-way ANOVA were used to test the association between genotypes and quantitative parameters, respectively.

RESULTS

No association was between the genotypes and the occurrence of AIS and the BMD of the spine and hip. The allelic frequency of T allele was 0.69 in AIS and control. However, the Cobb's angle was higher in patients with the homozygous T allele (Mean Cobb's angle: 38.1 degrees in TT vs 35.9 degrees in TC vs 33.2 degrees in CC group; p=0.04).

DISCUSSION

Interestingly, IGF-I polymorphism affects the curve severity of AIS though it was not associated with onset of AIS per se. It indicates that IGF-I may be a disease modifying gene. The importance of IGF-I in skeletal growth makes it a good candidate gene which would play a role in the documented association of rapid growth with curve progression in AIS.

The role of melatonin receptor 1B gene (MTNR1B) in adolescent idiopathic scoliosis--a genetic association study

Many studies have demonstrated the role of melatonin in the etiology of AIS. Previous studies have shown that there is no evidence of mutations in the melatonin receptor 1A gene in AIS patients. In this study, we have examined the role of melatonin receptor 1B in predisposition for AIS. Using haplotype block tagging technique, a set of tagging SNPs were defined for MTNR1B from the Han Chinese data of the International HapMap project. The association between the tagging of single nucleotide polymorphisms (tSNPs) in MTNR1B region and the occurrence of AIS was studied.

METHOD

473 AIS girls and 311 normal controls were recruited. The age range of the patients was between 10 and 18 years old. The maximum Cobb was recorded at latest follow-up in AIS patients. Three of five tSNPs were studied; they were all located within the coding region of the MTNR1B gene.

RESULTS

There was no significant difference in the genotype or allelic frequencies (AF) of the 3 tSNPs between AIS and controls. In a case-only analysis, no difference in curve severity in AIS patients was found among patients with different genotypes (by one-way ANOVA).

DISCUSSION

The 3 tSNPs showed no association with either the occurrence of AIS or the maximum Cobb angle within AIS girls. Further analysis of the remaining tSNPs within the regulatory region of the MTNR1B gene and other related genes in the melatonin signaling pathway may provide further information on the role of the melatonin in AIS girls.

Persistent osteopenia in adolescent idiopathic scoliosis--longitudinal monitoring of bone mineral density until skeletal maturity

The aim of this study was to monitor BMD changes occurring during periods of rapid growth and to investigate whether osteopenia was a persistent phenomenon in skeletally matured AIS girls. 196 AIS Chinese girls and 122 healthy controls, aged 11-16, were follow-up for 3.5 years. Bilateral femoral neck bone mineral density (BMD) and volumetric BMD (vBMD) of the distal tibia were obtained by dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT). Osteopenia was defined if the age-adjusted BMD was below or equal to -1 standard deviation (SD). The average age at the final follow-up was 16.8 years old. The median initial Cobb angle for this group of patients was 26 degrees. The prevalence of osteopenia at the baseline measurement was 35.9%. Longitudinal BMD results demonstrated that 86.0% of osteopenic AIS girls had persistently low BMD at the time of skeletal maturity (age of 16). vBMD of distal tibia of AIS was significantly lower than that of the controls throughout the age of 13 to 17 during the period of rapid growth. In addition, there were also significant differences in vBMD among AIS (moderate and severe group) and the controls by one-way ANOVA (p<0.05). The present study for the first time revealed that over 86% of osteopenic AIS patients had persistently low BMD, at both distal tibia and femoral neck regions, at the time of skeletal maturity. Early detection and treatment of AIS-related osteopenia might help in maximizing peak bone mass during peripubertal growth that thereby minimizing risks of developing osteoporotic fractures later in life.

Osteopenia: a new prognostic factor of curve progression in adolescent idiopathic scoliosis

BACKGROUND

Studies have shown that 27% to 38% of girls with adolescent idiopathic scoliosis have systemic osteopenia. The aim of this study was to investigate whether osteopenia could serve as one of the important prognostic factors in predicting curve progression.

METHODS

A prospective study was performed in 324 adolescent girls with adolescent idiopathic scoliosis who had a mean age of thirteen and a half years. Bone mineral density of the spine and both hips was measured at the time of the clinical diagnosis of scoliosis. All patients were followed longitudinally until skeletal maturity or until the curve had progressed > or =6 degrees . The univariate chi-square test and stepwise logistic regression were used to predict the prevalence of curve progression, and a receiver operating characteristic curve was plotted.

RESULTS

The overall prevalence of curve progression was 50%. The prevalence of osteopenia at the spine and hips was 27.5% and 23.1%, respectively. A larger initial Cobb angle (odds ratio = 4.6), a lower Risser grade (odds ratio = 4.7), premenarchal status (odds ratio = 2.5), osteopenia in the femoral neck of the hip on the side of the concavity (odds ratio = 2.3), and a younger age at the time of diagnosis (odds ratio = 2.1) were identified as risk factors in predicting curve progression. A predictive model was established, and the area under the receiver operating characteristic curve of the model was 0.80 (p < 0.01).

CONCLUSION

Osteopenia may be an important risk factor in curve progression. The measurement of bone mineral density at the time of diagnosis may serve as an additional objective measurement in predicting curve progression in adolescent idiopathic scoliosis. The bone mineral density-inclusive predictive model may be used in treatment planning for patients with adolescent idiopathic scoliosis who are at high risk of curve progression.

Effects of weight bearing and non-weight bearing exercises on bone properties using calcaneal quantitative ultrasound

OBJECTIVE

This study was designed to investigate bone properties using heel quantitative ultrasound (QUS) in young adults participating in various sports.

METHODS

A cross sectional study was performed on Chinese male students (n = 55), aged 18-22 years. Subjects with previous fractures or suffering from any diseases known to affect bone metabolism or taking any medication with such an effect, were not included. The subjects were categorised according to their main sporting activities, including soccer (n = 15) (a high impact, weight bearing exercise), dancing (n = 10) (a low impact, weight bearing exercise), and swimming (n = 15) (non-weight bearing exercise). A sedentary group acted as controls (n = 15). A reproducibility study of the velocity of sound (VOS) and the broadband ultrasound attenuation (BUA) measurement was performed and analysed using the intraclass correlation coefficient (ICC).

RESULTS

There was good intra-investigator and inter-investigator agreement (ICC > or = 0.8; p < 0.05) in the measurement of BUA and VOS. No significant differences in BUA and VOS (p > 0.05) were found between the dominant and non-dominant heel. Soccer players (137 +/- 4.3 dB/MHz; 1575 +/- 56 m/s; 544.1 +/- 48.4) and dancers (134.6 +/- 3.7 dB/MHz; 1538 +/- 46 m/s; 503.0 +/- 37.0) had significantly higher BUA, VOS, and stiffness index (SI) scores (p < 0.05), respectively, than swimmers (124.1 +/- 5.1 dB/MHz; 1495 +/- 42 m/s; 423.3 +/- 46.9) and the sedentary control group (119.9 +/- 6.1 dB/MHz; 1452 +/- 41 m/s; 369.9 +/- 46.4). A trend of a significant linear increase with the weight bearing and high impact exercise was revealed in all QUS parameters (p < 0.05).

CONCLUSION

This cross sectional study indicated that regular participation in weight bearing exercise in young people might be beneficial for accruing peak bone mass and optimising bone structure.