PADFrag: A Database Built for the Exploration of Bioactive Fragment Space for Drug Discovery.

Structural analyses of drugs and pesticides can enable the identification of new bioactive compounds with novel and diverse scaffolds as well as improve our understanding of the bioactive fragment space. The Pesticide And Drug Fragments (PADFrag) database is a unique bioinformatic-cheminformatic cross-referencing resource that combines detailed bioactive fragment data and potential targets with a strong focus on quantitative, analytic, and molecular-scale information for the exploration of bioactive fragment space for drug discovery ( http://chemyang.ccnu.edu.cn/ccb/database/PADFrag/ ). The main applications of PADFrag are the analysis of the privileged structures within known bioactive molecules, ab initio molecule library design, and core fragment discovery for fragment-based drug design. Other potential applications include prediction of fragment interactions and general pharmaceutical research.

High glucose improves healing of periodontal wound by inhibiting proliferation and osteogenetic differentiation of human PDL cells.

Periodontal ligament (PDL) cells play an important role in wound healing of periodontal tissues. Response of PDL cells' cellular activity to high-glucose concentration levels may be the key in understanding the relationship between periodontal disease and diabetes mellitus. We studied the effect of high-glucose medium on proliferation of PDL cells in vitro. PDL cells were cultured for 1, 4, 7, 10, 14 and 17 days in normal (1100 mg/l) glucose or in high (4500 mg/l) glucose medium. The 3-(4,5-dimethylithiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay for proliferation was performed. In order to evaluate the osteogenetic differentiation of human PDL cells, the cells were induced with normal- or high-glucose medium for 1, 7, 14, 21 and 28 days. The results indicated that high glucose significantly inhibited proliferation of PDL cells. Concerning the mineralised nodule formation, the percentage of calcified area to total culture dish of PDL cells in high glucose level was lower than that in normal glucose medium. The increase in alkaline phosphatase activity and collagen expression could be observed in high-glucose-containing osteogenetic factor. In conclusion, high glucose improves healing of periodontal wound by inhibiting proliferation and differentiation of PDL cells, which could explain for delayed periodontal regeneration and healing in diabetic patients.

Volar locking plate versus external fixation for the treatment of unstable distal radial fractures: a meta-analysis of randomized controlled trials.

BACKGROUND: The choice between volar locking plates (VLP) and external fixation (EF) for unstable distal radius fractures have not reached a consensus. The meta-analysis of randomized controlled trials was performed to compare VLP with EF to determine the dominant strategy. MATERIALS AND METHODS: Meta-analysis was performed with a systematic search of studies conducted by using the PubMed, Embase, and Cochrane Central Register of Controlled Trials databases. The randomized controlled trials that compared VLP with EF was identified. Characteristics, functional outcomes, radiological results, and complications were manually extracted from all the selected studies. RESULTS: Six studies encompassing 445 patients met the inclusion criteria. There was significant difference between two procedures in disabilities of the arm shoulder and hand scores at 3,6, and 12 mo, visual analogue scale at 6 mo, grip strength at 3 mo, supination at 3 and 6 mo, extension at 3 mo, ulnar variance at 12 mo, and reoperation rate at 12 mo, postoperatively. However, there was no significant difference between flexion, pronation, radial deviation, and ulnar deviation at all follow-up points postoperatively and overall complications at 12 mo, postoperatively. CONCLUSIONS: EF had less reoperative rate due to complications, however, VLP had advantages in functional recovery in the early period after surgery, but two methods had similar functional recovery at 12 mo, postoperatively. Clinician should make the treatment decision with great caution for the patients who sustained unstable distal radial fractures.

Nicotine induction of theta frequency oscillations in rodent medial septal diagonal band in vitro.

AIM: This study aimed to examine the role of the nicotinic receptor (nAChR) in the generation of theta oscillations (4-12 Hz) in vitro. METHODS: Electrophysiological studies were performed on medial septal diagonal band area (MSDB) slices to measure theta oscillation. Immunofluorescence and confocal microscopy studies were carried out to detect α4 nAChR and ß2 nAChR subunits in perfused-fixed tissue from VGluT2-GFP and GAD67-GFP transgenic mice. RESULTS: Application of nicotine to MSDB slices produced persistent theta oscillations in which area power increased in a dose-responsive manner. This activity was inhibited by GABAA receptor antagonists and partially by ionotropic glutamate receptor antagonists, indicating the involvement of local GABAergic and glutamatergic neurons in the production of the rhythmic activity. The nicotine-induced theta activity was also inhibited selectively by non-α7*nAChR antagonists, suggesting the presence of these receptor types on GABAergic and glutamatergic neuron populations in the MSDB. This was confirmed by immunofluorescence and confocal microscopy studies in transgenic mice in which the GABAergic and glutamatergic neurons express green fluorescent protein (GFP), showing localisation of ß2 nAChR and α4 nAChR subunits, the most common constituents of non-α7*nAChRs, in both cell types in the MSDB. CONCLUSION: Theta activity in the MSDB may be generated by tonic stimulation of non-α7*nAChRs.

ACID: a free tool for drug repurposing using consensus inverse docking strategy.

Drug repurposing offers a promising alternative to dramatically shorten the process of traditional de novo development of a drug. These efforts leverage the fact that a single molecule can act on multiple targets and could be beneficial to indications where the additional targets are relevant. Hence, extensive research efforts have been directed toward developing drug based computational approaches. However, many drug based approaches are known to incur low successful rates, due to incomplete modeling of drug-target interactions. There are also many technical limitations to transform theoretical computational models into practical use. Drug based approaches may, thus, still face challenges for drug repurposing task. Upon this challenge, we developed a consensus inverse docking (CID) workflow, which has a ~ 10% enhancement in success rate compared with current best method. Besides, an easily accessible web server named auto in silico consensus inverse docking (ACID) was designed based on this workflow (http://chemyang.ccnu.edu.cn/ccb/server/ACID).

[Effect of Beclin-1 shRNA on hypoxia-induced autophagy in SH-SY5Y cells].

OBJECTIVE: To observe the effect of hypoxia on autophagy in Beclin-1-knockdown SH-SY5Y cells by constructing a stable transfected SH-SY5Y cell lines of silencing Beclin-1 gene. METHODS: Beclin-1shRNA lentiviral vector and negative control lentiviral vector were constructed; the vector was transfected into SH-SY5Y cells; then the expression of Beclin-1 mRNA was detected by RT-PCR, the level of Beclin-1 protein was detected by Western blot. CCK-8 method was used to determine the effect of Beclin-1 knockdown on the viability of SH-SY5Y cells. Next, the blank control, negative control and transfected cells were cultured under 21% normoxia and 5% hypoxia conditions. The expression of LC3 protein in each group was detected by Western blot and the autophagic bodies were observed by electron microscopy. RESULTS: Beclin-1 shRNA significantly inhibited the expression of Beclin-1 mRNA and protein in SH-SY5Y cells; after silencing Beclin 1 gene, the survival rate of Beclin-1 shRNA group cells was no different from that of negative control (NC) group. After 5% hypoxia treatment, compared with NC group, the ratio of LC3Ⅱ/LC3Ⅰand the number of autophagy bodies were all decreased in Beclin-1 shRNA group. CONCLUSIONS: Beclin-1 knockdown SH-SY5Y cell lines and negative control cell lines were successfully established. Lentivirus-mediated Beclin-1 shRNA has no effect on the viability of SH-SY5Y cells, but can inhibit hypoxia-induced autophagy.

A single nucleotide polymorphism in the matrix metalloproteinase-1 promoter enhances oral squamous cell carcinoma susceptibility in a Chinese population.

We genotyped 96 oral squamous cell carcinoma (OSCC) patients for the 1G/2G polymorphism of matrix metalloproteinase-1 (MMP-1) promoter -1607 bp using PCR-RFLP. A control population of 120 frequency-matched subjects was also genotyped for the same polymorphism. The detection frequency of 2G allele was significantly higher in OSCC subjects (76%) than in the control group (56.7%). The frequency of 2G allele had a significant difference between the OSCC and controls group (p = 0.00, Odds Ratio, OR = 2.232, 95% CI = 1.477-3.372). The genotype 2G/2G was found in 57.3% of the OSCC, and 34.2% in the controls. The proportion of 2G homozygote (2G/2G) was significantly higher in the OSCC group when compared to controls (p = 0.001, OR = 2.585, 95% CI = 1.487-4.494). OSCC patients were stratified by clinicopathological parameters including gender, smoking, clinical stage and lymph node metastasis, but the only statistically significant association with MMP-1 genotype was with smoking. The results showed that a SNP in the MMP-1 promoter -1607 bp was associated with OSCC susceptibility in a Chinese population.

[Protective effect of hypoxic preconditioning on SH-SY5Y cells injured by oxygen-glucose deprivation].

OBJECTIVE: To investigate the protection effects of hypoxic preconditioning(HPC) on the SH-SY5Y cell injured by oxygen-glu-cose deprivation(OGD),and to discuss the possible mechanism. METHODS: SH-SY5Y cells were randomly divided into 4 groups. In normal group,the cells were cultured without OGD treatment. In HPC group,the cultured SH-SY5Y cells were treated for 5 days by intermittently ex-posing to hypoxic gas mixture (2% O2,5% CO2) for 30 min in every day. In OGD group,the culture medium was replaced by glucose-free medium and the cells were transferred to a humidified incubation chamber flushed by a gas mixture of 1% O2 and 5% CO2 for 10 h. After that, the cells were fed with glucose-supplemented medium and cultured under normoxic condition for 24 h. In HPC+OGD group,the cultured SH-SY5Y cells were treated for 5 days by intermittently exposing to hypoxic gas mixture for 30 min in each day, then the cells were given the same treatments as those in OGD group. The cell viability was assessed by MTT assay. The degree of the cell damage was evaluated by deter-mining lactate dehydrogenase (LDH) leakage. TUNEL staining were used to detect the variation of cell apoptosis. The expression of Caspase 3 and hypoxia inducible factor-1α(HIF-1α) at protein levels was examined by Western blot. RESULTS: Hypoxic preconditioning relieved the cells apoptosis,decreased the amount of LDH leakage and improved the viability of SH-SY5Y cells injured by OGD (P<0.05). Western blot showed that the expression of Caspase 3 protein in HPC+OGD group was significantly lower than that in OGD group (P<0.05); HIF-1α protein expression was significantly higher than that of OGD group (P<0.05). CONCLUSIONS: Hypoxic preconditioning has protective effect on in vitro cultured SH-SY5Y cells injured by OGD. The mechanism may be related to the increase of HIF-1a protein.

[Development and effectiveness evaluation of time-resolved fluoroimmunoassay kit for detection of Schistosoma japonicum].

OBJECTIVE: To develop a kit of time-resolved fluoroimmunoassay (TRFIA) for detection of Schistosoma japonicum protein SjP38, and evaluate its effectiveness. METHODS: The anti 9G7 SjP38 monoclonal antibody was used as the capture anti-body coated with 96-hole plate, and the Eu3+ labeled 1A6 monoclonal antibody was used as the detection antibody to establish the TRFIA SjP38 kit. In addition, the accuracy, sensitivity, precision, stability and coincidence rate to pathogenic diagnosis of the kit were evaluated. RESULTS: This established kit possessed high accuracy, wide linear range from 2 to 1 250 ng/ml, high sensitivity with the minimum detectable concentration of 0.14 ng/ml, and good precision (the coefficient variation of the intra- and inter-assay were 3.6% to 4.6% and 5.1% to 6.7%, respectively). The stability tests showed that the reagents could be stable for six months at 4 ℃, 7 d at 37 ℃. The positive and negative corresponding rates to the pathogen detection method were 95% and 100% respectively. CONCLUSIONS: All the performance and detection indicators of the kit have reached the requirements of clinical test, but its clinical application still needs further validation.

Biomechanical study on the treatment of intertrochanteric fracture of A3.3 type with medial sustainable nail and proximal femoral anti-rotation nail / 中国骨伤

OBJECTIVE@#A3 intertrochanteric fracture is an extremely unstable fracture, which is often treated with intramedullary nail, but the implant failure is common due to the posterior medial fragment cannot be reconstructed. A new medial sustainable nail (MSN-Ⅱ) which can reconstruct the femoral medial support by sustainable screw was introduced in this study. The mechanical effect was verified by biomechanical experiment.@*METHODS@#The loss medial support model of intertrochanteric fracture (A3) was made by artificial Sawbones model, fixed with MSN-Ⅱ and PFNA-Ⅱ, underwent axial loading and axial failure tests. The axial stiffness, yield load, displacement of head-neck fragment and torsional angle of fracture site of these nails were recorded and compared for biomechanical differences. The effect of early reconstruction of medial support with MSN-Ⅱ was determined.@*RESULTS@#The axial stiffness, yield load, the displacement of head and neck fragment when the axial load was 1 800 N and torsional angle of the fracture site after the axial failure test of MSN-Ⅱ were (222.76 ±62.46) N /mm, (4 241.71 ±847.42) N, (11.51 ±0.62) mm, (1.71 ±0.10)° respectively, while the PFNA -Ⅱ was (184.58±40.59) N /mm, (3 058.76±379.63) N, (16.15±1.36) mm, (2.52±0.26)°respectively. The difference between the two groups was statistically significant.@*CONCLUSION@#The axial stiffness of MSN-Ⅱ is better than that of PFNA-Ⅱ. The MSN-Ⅱ can bear more loads when fixed A3.3 intertrochanteric fracture and has greater axial and rotational stability. It is an effective means to reconstruct the medial support of A3 intertrochanteric fracture.

Medial support nail and proximal femoral nail antirotation in the treatment of reverse obliquity inter-trochanteric fractures (Arbeitsgemeinschaft fur Osteosynthesfrogen/Orthopedic Trauma Association 31-A3.1): a finite-element analysis / 中华医学杂志(英文版)

BACKGROUND@#The reverse obliquity inter-trochanteric fracture is a distinct fracture pattern that is mechanically different from most inter-trochanteric fractures and the optional treatment of it is still controversial. The purpose of this study was to compare differences in the efficacy of a novel nail (medial support nail [MSN-II]) and proximal femoral nail anti-rotation (PFNA-II) in the treatment of reverse obliquity inter-trochanteric fractures (Arbeitsgemeinschaft fur Osteosynthesfrogen/Orthopedic Trauma Association [AO/OTA] 31-A3.1) using finite-element analysis.@*METHODS@#Modeling software was used to establish a three-dimensional model of MSN-II and PFNA-II and an A3.1 inter-trochanteric fracture model. Abaqus software was used to implement different force loads to compare finite-element biomechanical parameters such as the maximum stress in implant and the displacement of fracture site.@*RESULTS@#The femoral stress, implant stress and fracture site displacement of MSN-II was less than that of PFNA-II. The results indicated that the maximal femoral stress was 581 MPa for PFNA-II and 443 MPa for the MSN-II. The maximum stress values in the PFNA-II and MSN-II models were 291 and 241 MPa, respectively. The maximal displacements of the fracture site were 1.47 and 1.16 mm in the PFNA-II and MSN-II models, respectively.@*CONCLUSION@#Compared with PFNA-II for inter-trochanteric fracture (AO/OTA 31-A3.1), MSN-II which was designed with a triangular stability structure can provide better biomechanical stability. The MSN-II may be a feasible option for the treatment of reverse obliquity inter-trochanteric fracture.

Three-dimensional mapping of intertrochanteric fracture lines / 中华医学杂志(英文版)

Background@#Available research about the anatomic patterns of intertrochanteric fractures is lacking, and fracture mapping has not previously been performed on intertrochanteric fractures. This study aimed to determine the major trajectories of intertrochanteric fracture lines using computed tomography data from a series of surgically treated patients.@*Methods@#In this study, 504 patients with intertrochanteric fractures were retrospectively analyzed. Fracture patterns were graded according to Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification. Fracture lines were transcribed onto proximal femoral templates and graphically superimposed to create a compilation of fracture maps that were subsequently divided into anterior, posterior, lateral, and medial fracture maps to create a three-dimensional (3D) pattern by reducing fragments in the 3D models. The fracture maps were then converted into frequency spectra. The major fracture patterns were assessed by focusing on the lateral femoral wall, lesser trochanter, intertrochanteric crest, and inner cortical buttress.@*Results@#Anterior, posterior, lateral, and medial fracture maps were created. The majority of fracture lines (85.9%, 433/504) on the anterior maps were along the intertrochanteric line where the iliofemoral ligament was attached. In the medial plane, the majority of fracture lines (49.0%, 247/504) shown on the frequency spectrum included the turning point involving the third quadrant. In the posterior plane, the majority of fracture lines (52.0%, 262/504) involved the intertrochanteric crest from the greater to the lesser trochanter. In the lateral plane, the majority of fracture lines (62.7%, 316/504) involved the greater trochanter at the gluteus medius attachment.@*Conclusions@#The fracture patterns observed in the present study might be used to describe morphologic characteristics and aid with management strategies. Further classifications or modifications that incorporate the fracture patterns identified in this study may be used in future research.

Three-dimensional mapping of intertrochanteric fracture lines / 中华医学杂志(英文版)

BACKGROUND@#Available research about the anatomic patterns of intertrochanteric fractures is lacking, and fracture mapping has not previously been performed on intertrochanteric fractures. This study aimed to determine the major trajectories of intertrochanteric fracture lines using computed tomography data from a series of surgically treated patients.@*METHODS@#In this study, 504 patients with intertrochanteric fractures were retrospectively analyzed. Fracture patterns were graded according to Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification. Fracture lines were transcribed onto proximal femoral templates and graphically superimposed to create a compilation of fracture maps that were subsequently divided into anterior, posterior, lateral, and medial fracture maps to create a three-dimensional (3D) pattern by reducing fragments in the 3D models. The fracture maps were then converted into frequency spectra. The major fracture patterns were assessed by focusing on the lateral femoral wall, lesser trochanter, intertrochanteric crest, and inner cortical buttress.@*RESULTS@#Anterior, posterior, lateral, and medial fracture maps were created. The majority of fracture lines (85.9%, 433/504) on the anterior maps were along the intertrochanteric line where the iliofemoral ligament was attached. In the medial plane, the majority of fracture lines (49.0%, 247/504) shown on the frequency spectrum included the turning point involving the third quadrant. In the posterior plane, the majority of fracture lines (52.0%, 262/504) involved the intertrochanteric crest from the greater to the lesser trochanter. In the lateral plane, the majority of fracture lines (62.7%, 316/504) involved the greater trochanter at the gluteus medius attachment.@*CONCLUSIONS@#The fracture patterns observed in the present study might be used to describe morphologic characteristics and aid with management strategies. Further classifications or modifications that incorporate the fracture patterns identified in this study may be used in future research.

[Long-term results of dual anti-collagen membrane in guided tissue regeneration].

OBJECTIVE: To evaluate the long-term clinical effect of dual anti-collagen membranes in guided tissue regeneration (GTR). METHODS: This randomized clinical trial included 26 teeth in 24 patients, presenting a total of 31 lesions consisting of intrabony defects and furcation defects. Twenty-six teeth were divided into two groups and treated by GTR with dual anti-collagen membranes and atelocollagen membranes, respectively. At baseline, 6 months, 1, 3 and 6 years, the following parameters were recorded: clinical attachment level, probing depth, gingival recession and the quantity of alveolar bone analyzed by computer assisted densitometry image analysis (CADIA). RESULTS: At 1 year after GTR surgery, the gain of clinical attachment in dual anti-collagen membranes group was (3.93 ± 1.74) mm, compared with (2.25 ± 1.90) mm in atelocollagen group (P = 0.044). The increasing of the value of CADIA in dual anti-collagen membrane and atelocollagen group were (53.14 ± 21.35) and (32.96 ± 17.97), P = 0.031. At 3 and 6 years, clinical parameters remained basically stable in both groups, compared to that at 1 year after surgery. CONCLUSIONS: The regeneration of periodontal tissues obtained by GTR with dual anti-collagen membranes could be maintained on a long-term basis.

[Establishment and application of an intact natural model of human dental plaque biofilm].

PURPOSE: Human dental plaque is implicated in a number of oral diseases. Collection of its undisturbed intact structure facilitates observing the formation and the effect of treatment. This study established a model in vivo to collect intact natural dental plaque biofilm, and observed the features and evaluated the immediate penetration and bactericidal effect of an essential oil (EO) mouthrinse on it at different periods. METHODS: Three 500 microm wide grooves were cut into hydroxyapatite (HA) discs. The discs were worn by six volunteers for 6, 24 and 48 hours, then broken into halves, one served as control, while the other received a one-minute extra-oral EO mouthrinse treatment. 5, 15 and 30 minutes later, the plaque was visualized with a vitality staining technique to observe the sustained changes of biofilm structure in situ and the effect of EO on intact biofilm. The biofilm thickness and fluorescent density of vital and total bacteria were obtained through diagram analysis, assessing the percentage of thickness and fluorescent density of vital to total bacteria. All data analysis was performed using SPSS 13.0 software package. One-way ANOVA and Student-Neuman-Keuls tests were used. RESULTS: The thickness of 6h, 24h and 48 h biofilm was (11.92 + or - 4.63) microm, (18.63 + or - 4.66)microm, (27.55 + or - 6.35) microm, respectively, which increased significantly within 48 hours (P<0.05), especially those within 6 hours. The percentages of thickness and fluorescent density of vital to total bacteria at different periods showed no significant changes (P>0.05). For 6-hour samples, plaque vitality for thickness and fluorescent density decreased significantly within 5 minutes after exposure to the EO (P<0.05). Meanwhile, for 24, 48-hour samples, plaque vitality decreased significantly within 15 minutes (P<0.05). CONCLUSIONS: This study successfully establishes a model for collecting natural undisturbed plaque biofilm in situ, showing the changes constantly within 48 hours. EO mouthrinse has an immediate penetration and antimicrobial effect on the sustained dental plaque biofilm, especially 15 minutes later.

Mid-term effect of unilateral pedicle screw fixation and transforaminal lumbar interbody fusion in the treatment of lumbar degenerative diseases / 中国骨伤

<p><b>OBJECTIVE</b>To investigate the feasibility and the mid-term effects of unilateral pedicle screw fixation and transforaminal lumbar interbody fusion in treating lumbar degenerative diseases.</p><p><b>METHODS</b>From August 2005 to May 2010, 56 patients with lumbar degenerative diseases underwent lumbar posterolateral fusion,their clinical data were retrospective analyzed. The patients were divided into two groups (unilateral group and bilateral group) according to fixation methods,27 patients in unilateral group who were underwent unilateral pedicle screw fixation, including 18 males and 9 females with a mean age of (57.5 ± 7.1) years old (ranged from 41 to 66 years); and 29 patients in bilateral group who were treated with bilateral pedicle screw fixation (on the basis of the above, with contralateral vertebral pedicle screw fixation), including 19 males and 10 females with a mean age of (54.6 ± 5.1) years old (ranged from 43 to 68 years). The clinical data such as operation time, blood loss volume, hospitalization time and cost were compared between two groups. JOA score system was used to evaluate the neurological function. And fusion status and cage-related complication were also analyzed.</p><p><b>RESULTS</b>All patients were followed up from 36 to 60 months with an average of 45.8 months. No iatrogenic nerve, blood vessels or organs injury were found during operation. Operation time, blood loss volume, hospitalization time and cost in unilateral group were better than that of bilateral group (P < 0.05). There was no significant difference in JOA score between two groups (P > 0.05). Two patients in unilateral group developed with cage related complications, 1 case was cage displacement and 1 case was cage subsidence, while 2 patients in bilateral group developed with complications of no-fusion, and there was no significant differences between two groups (P = 0.58).</p><p><b>CONCLUSION</b>Unilateral pedicle screw fixation is a satisfactory method and can obtain good effects in treating lumbar degenerative diseases in mid-term, however, the indications should be well considered.</p>

Three-dimensional finite element analysis on mechanical behavior of the bone remodeling and bone integration between the bone-implant interface after hip replacement / 中国骨伤

<p><b>OBJECTIVE</b>To discuss the primary stability of the fixed interface between the cementless prosthesis and femur, and its influence on bone ingrowth and secondary stability under the roughened surface and press fit of different prostheses by finite element analysis.</p><p><b>METHODS</b>:A three-dimensional finite element module of total hip arthroplasty (THA) was developed with Mimics software. There was a collection of data when simulating hip arthroplasty. The frictional coefficient between the fixed interface was 0,0.15,0.40 and 1.00 representing the roughness of prosthesis surface. The press fit was 0, 0.01,0.05 and 0.10 mm according to the operation. The Vion Mises stress distribution and the contact pressure,friction stress and relative sliding displacement between the interface were analysed and compared when simulating the maneuver of climbing stairs.</p><p><b>RESULTS</b>At a fixed press fit of 0.05 mm,the contact pressure between the interface was 230 , 231, 222 and 275 MN under four different frictional coefficient (0,0. 15,0.40 and 1.00) with little change; the relative sliding displacement was 0.529, 0.129, 0.107 and 0.087 mm with a consistent and obvious decline. As the fixed frictional coefficient was 0.40,the contact pressure between the interface were 56.0,67.7 ,60.4 and 49.6 MN under four different press fit (0, 0.01, 0.05 and 0.10 mm) with a reduction; the relative sliding displacement was 0.064,0.062,0.043 and 0.042 mm with an obvious decline, and there was a maximal friction stress when press fit of 0.01 mm.</p><p><b>CONCLUSION</b>There is a dynamic process of the bone remodeling and bone integration between the interface after hip replacement, determining the long-term outcome. The interface clearance and the frictional coefficient are the key factors of the bone integration.</p>

[Protective effect of baicalin on experimental periodontitis in rats and its possible mechanisms].

OBJECTIVE: To investigate the effect of baicalin on the experimental periodontitis in rats, as well as the expression of MMP-1, MMP-2, MMP-9. METHODS: Twenty-seven adult male Sprague-Dawley rats were divided into three groups, with 9 rats in each group. A nylon thread was placed around the lower first molars of rats, which were sacrificed after 7 days. Baicalin (200 mg/kg) was administered to the experimental group by oral gavage, starting one day before the induction of periodontitis. The negative control group received vehicle (0.5% carboxymethylcellulose) alone. The blank control group did not get induction of periodontitis. The alveolar bone loss (ABL) and the area fraction (AA% ) occupied by collagen fibers were assessed. MMP-1, MMP-2 and MMP-9 protein expressions in the gingiva were detected by immunohistochemistry. RESULTS: Baicalin treatment significantly decreased ABL compared with the negative control group (P = 0.009). AA% of collagen fibers was significantly higher in baicalin-treated group than in the negative control group (P = 0.047). Baicalin treatment significantly down-regulated the protein expression for MMP-1 (P = 0.023) and MMP-9 (P = 0.042) and decreased the expression for MMP-2 (P = 0.099) compared with the negative control group. CONCLUSIONS: Baicalin protects against tissue damage in ligature-induced periodontitis in rats, which might be mediated in part by its inhibitory effect on the expression of MMP-1, MMP-2 and MMP-9.

Effects of recombinant human osteoprotegerin and recombinant RANK protein on the differentiation of osteoclast precursors / 中国骨伤

<p><b>OBJECTIVE</b>To compare the effect of recombinant OPG-Fc and recombinant RANK protein on the differentiation of osteoclast precursors.</p><p><b>METHODS</b>Mouse osteoblasts cell lines were incubated with osteoclast precursors cell lines RAW 264.7 for 9 days with 10(-5) g/L rhRANK or rhOPG-Fc or PBS added to the coculture system. TRAP stain positive cells counting and cortical bone pit formation counting were performed in the 9th day.</p><p><b>RESULTS</b>Multinuleated TRAP stain positive cells were observed in the cocluture systems after 6 days incubation,and plenty of mature osteoclasts could be observed in the 9th day. With the addition of 10(-5) g/L rhOPG-Fc or rhRANK, multinucleated giant cells and cortical bone pit formation couting decreased significantly compared with the control group, and the rhRANK group decreased more significantly than the rhOPG-Fc group.</p><p><b>CONCLUSIONS</b>Both rhOPG-Fc and rhRANK can inhabit the differentiation of osteoclast precursors and prevent them forming mature osteoclasts,moreover,the rhRANK shows the significant inhabition effect than the rhOPG-Fc.</p>

Finite element analysis on a modified cannulated screw for fixation of femoral neck fracture / 医用生物力学

Objective To establish the three-dimensional finite element model of the cannulated screws for fixing the femoral neck fracture, and investigate stress distributions on three cannulated screws as well as determine whether internal fixation by a modified cannulated screw can provide sufficient stiffness and strength for the fixation. Methods The 3D finite element model was internal-fixed at the angle of 127°with femoral shaft under the inverted triangle mode to simulate loading on single legged standing condition. Stresses on three screws (No 1: the underneath screw, No 2: the anterosuperior screw, No 3: the posterosuperior screw) were calculated at different Pauwels angle (50°, 60°, 70°, 80°), respectively. A bore was drilled in the screw with the largest stress to study the effect of bore size and bore direction on the femoral neck fracture model with screw fixation. Results The stresses of three screws increased with the Pauwels angle increasing and reached the maximum value at 80°. The maximum stresses on No.1, No.2 and No.3 screw were 304, 515 and 154 MPa, respectively. When the No 2 screw had an opening bore with 1 mm in diameter, and the direction of the bore was not between 150°and 195°, the stresses on three screws were all within the safe limits. Conclusions From the mechanical point of view, three screws are subject to different stresses. The cannulated screws with side bore have good biomechanical properties for fixing the femoral neck fracture with safety and reliability, which can provide advantages for accelerating fracture healing by injecting drugs through the central and side bore into the fracture side.