Biomechanical validation of computer assisted planning of periacetabular osteotomy: A preliminary study based on finite element analysis

Periacetabular Osteotomy (PAO) is a joint preserving surgical intervention intended to increase femoral head coverage and thereby to improve stability in young patients with hip dysplasia. Previously, we developed a CT-based, computer-assisted program for PAO diagnosis and planning, which allows for quantifying the 3D acetabular morphology with parameters such as acetabular version, inclination, lateral center edge (LCE) angle and femoral head coverage ratio (CO). In order to verify the hypothesis that our morphology-based planning strategy can improve biomechanical characteristics of dysplastic hips, we developed a 3D finite element model based on patient-specific geometry to predict cartilage contact stress change before and after morphology-based planning. Our experimental results demonstrated that the morphology-based planning strategy could reduce cartilage contact pressures and at the same time increase contact areas. In conclusion, our computer-assisted system is an efficient tool for PAO planning.

Variation of craniocervical junction volume as an effective parameter for basilar invagination treatment

OBJECTIVE

The major pathological change in basilar invagination (BI) is represented in the decrease of craniocervical junction (CVJ) volume resulting from abnormal bone protrusion around the foramen magnum. The diagnosis and clinical evaluation of BI is mainly based on the clinical manifestations and radiographic measurements by means of calculation of the scan lines of CVJ in X-ray, CT and MRI. With the transoral decompression atlantoaxial reduction plate (TARP III) system, the decompression, reduction and fixation can be achieved to decompress and stabilize medulla spinalis change the position of the dens in CVJ, thus expand the CVJ relative volume, relieve the compression on medulla spinalis and the nerve injury. However, the correlation between the dens position change and the variation of CVJ has not been established previously. This study focused on the clinical significance of the variation of craniocervical junction (CVJ) volume caused by the dens position change for the treatment of BI.

PATIENTS AND METHODS

We've performed an analysis of data from 62 BI patients admitted from January 2008 to May 2013, who were treated by TARP III system. The data include preoperative, postoperative JOA scores (Japanese Orthopaedic Association scores, 17 points method), preoperative and postoperative X-ray, thin-slice CT scan with three-dimensional reconstruction and MRI scan to measure the cervicomedullary angle (CMA). We have analyzed the preoperative and postoperative three-dimensional CT data by means of MIMICS 10.01 software system according to the Box volume (BV) method to determine the changes of CVJ volume resulting from preoperative and postoperative dens position change, assessed the correlation between the CVJ volume changes and the JOA scores with correlation between CMA change and the JOA scores. All data were analyzed by paired t-test and Pearson correlation analysis.

RESULTS

In all 62 patients, JOA scores were recovered from preoperative 9.26 ± 1.66 to postoperative 13.02 ± 1.44, CMA change rate was 21%, and CVJ volume change rate was 36%. The CMA change rate and the JOA score recovery rat exhibited relevance, as Pearson's correlation coefficient was 0.46 (p < 0.005). The Pearson's correlation coefficient between CVJ volume change rate and JOA score recovery rate was 0.63 (p < 0.005), and the CVJ volume change rate was significantly different while compared with the correlation between CMA change rate and JOA score (p < 0.005).

CONCLUSIONS

the CVJ volume change rate is a sensitive and reliable parameter for the evaluation of neurological function improvement in patients with BI. It can be used as a predictor to evaluate the postoperative neurological recovery.

[Dentin barrier cytotoxicity test with three-dimensional cell cultures]

OBJECTIVE

To evaluate the cytotoxicity of four dentin filling materials and two dentin adhesives with a dentin barrier test and to compare the results with those in a conventional filter diffusion test in order to investigate the advantages of the dentin barrier test.

METHODS

Eugenol cement, zinc phosphate cement, adhesive glass ionomer cement, composite resin and two self-etching adhesives (REMI BOND and Adper Easy One) were tested. In the dentin barrier test, L929 mouse fibroblasts were three-dimensional cultured in polystyrene meshes. The dentin disks were cut from the human third molars, near the pulp and in parallel with the occlusal surface, and their permeability within the measurement area was evaluated by a hydraulic permeability device. A mesh with the cells was placed in the "pulp cavity" of the chamber and one dentin disk was put on the cell mesh and its "pulp side" was in contact with the mesh. The test materials and controls were in contact with the "occlusal side" of the dentine disks for 24 h. The cell viability was obtained with MTT assay and the results were expressed as a percentage of control tissues. The Mann-Whitney U test was used to make the statistical analyses. In the filter diffusion test, after a 24 h contact between the test materials and the filters with monolayer cells, the filters were dyed and the grades of cytotoxicity were decided.

RESULTS

A mean permeability of the dentin disks near the pulp was 0.293 μL/(min×cm(2)×cmH(2)O)(1 cmH(2)O=0.098 kPa); In the dentin barrier test, Eugenol cement, REMI BOND and Adper Easy One respectively reduced the cell survival rates to 82%, 63% and 54%. Other materials showed no or very low toxic reactions; In the filter diffusion test, the light-curing composite resin was moderately cytotoxic, the dental adhesive glass ionomer cement was mildly cytotoxic and the others were severely cytotoxic; All the six materials in the dentin barrier test had lower cytotoxicity than in the filter diffusion test.

CONCLUSION

The cytotoxicity of the test materials using the dentin barrier test with three-dimensional cell cultures is lower than that in the filter diffusion test, which has good correlation with the clinical situation.

Pharmacokinetics of cefquinome in tilapia (Oreochromis niloticus) after a single intramuscular or intraperitoneal administration

The pharmacokinetics of cefquinome was studied in plasma after a single dose (10 mg/kg) of intramuscular (i.m.) or intraperitoneal (i.p.) administration to tilapia (Oreochromis niloticus) in freshwater at 30 °C. Ten fish per sampling point were examined after treatment. The data were fitted to two-compartment open models following both routes of administration. The estimates of total body clearance (CL/F), volume of distribution (Vd/F), and absorption half-life (T1/2ka ) were 0.049 and 0.037 L/h/kg, 0.41 and 0.33 L/kg, and 0.028 and 0.035 h following i.m. and i.p. administration, respectively. After i.m. injection, the elimination half-life (T1⁄2β ) was calculated to be 5.81 h, the maximum plasma concentration (Cmax ) to be 49.40 μg/mL, the time to peak plasma cefquinome concentration (Tmax ) to be 0.14 h, and the area under the plasma concentration-time curve (AUC) to be 204.6 μg h/mL. Following i.p. administration, the corresponding estimates were 6.05 h, 44.39 μg/mL, 0.17 h and 267.8 μg h/mL. The minimum inhibitory concentrations of cefquinome, determined for 30 strains of Streptococcus agalactiae isolated from diseased tilapia, ranged from 0.015 to 0.12 μg/mL. Results from these studies support that 10 mg cefquinome/kg body weight daily could be expected to control tilapia bacterial pathogens inhibited in vitro by a minimal inhibitory concentration value of ≤2 μg/mL.

[Evaluation method with radiographic image quality indicator for internal defects of dental casting metallic restoration]

OBJECTIVE

To develop a new kind of dental radiographic image quality indicator (IQI) for internal quality of casting metallic restoration to influence on its usage life.

METHODS

Radiographic image quality indicator method was used to evaluate the depth of the defects region and internal quality of 127 casting metallic restoration and the accuracy was compared with that of conventional callipers method.

RESULTS

In the 127 cases of casting metallic restoration, 9 were found the thickness less than 0.7 mm and the thinnest thickness only 0.2 mm in 26 casting metallic crowns or bridges' occlusal defects region. The data measured by image quality indicator were consistent with those measured by conventional gauging. Two metal inner crowns were found the thickness less than 0.3 mm in 56 porcelain crowns or bridges. The thickness of casting removable partial denture was more than 1.0 mm, but thinner regions were not found. It was found that in a titanium partial denture, the X-ray image of clasp was not uniform and there were internal porosity defects in the clasp.

CONCLUSION

Special dental image quality indicator can solve the visual error problems caused by different observing backgrounds and estimate the depth of the defects region in the casting.

Serum microRNA panel as biomarkers for early diagnosis of colorectal adenocarcinoma

Background:

Currently, none of the available colorectal adenocarcinoma (CAC) testing has been established as a well-accepted diagnosis tool, particularly for the early stage of CAC. The recent discovery of serum microRNA (miRNA) profile has provided a new auxiliary approach for tumour diagnosis. Our study is involved in the global analysis of serum miRNAs during the normal–colorectal adenoma (CA)–CAC sequence.

Methods:

Serum samples were collected from 307 CAC patients, 164 CA patients and 226 healthy controls. Differentially expressed serum miRNAs were screened with Miseq sequencing followed by the reverse transcription PCR (RT–qPCR) validation. The miRNA panel was developed with a logistic regression model and validated using an independent cohort. The miRNA levels in CAC patients of different clinical stages and CA patients of different grades were compared. Receiver operating characteristic curves were constructed to evaluate the diagnostic accuracy of the panel.

Results:

The Miseq sequencing results revealed 15 differentially expressed miRNAs in the intersection of CAC vs CA and CA vs healthy controls according to our criteria. After the selection and validation process via RT–qPCR, we identified a four-miRNA panel (miR-19a-3p, miR-223-3p, miR-92a-3p and miR-422a) with a high diagnostic accuracy of CAC. Even in the low-carcinoembryonic antigen level group, the diagnostic accuracy of this miRNA panel was still acceptable (AUC=0.810). Surprisingly, our results indicated that the miRNA panel could differentiate stage I/II CAC from controls. In addition, this panel could also differentiate CA from CAC (AUC=0.886) and healthy controls (AUC=0.765).

Conclusions:

We established a serum four-miRNA panel with considerable clinical value in the early-stage diagnosis of CAC.

Model and Numerical Simulation for the Second Penetration in Water-assisted Injection Molding

Unlike gas-assisted injection molding, subsequent penetration occurs on the radial direction after water displacing polymer melt in cavity due to the incompressibility and fast cooling of water in water-assisted injection molding. To simulate this second penetration, a dimensionless method was employed to simplify the governing equations for melt flow. Based on the reduced model, a formula was derived via mathematical inference to calculate the second penetration velocity and distance. In order to catch the huge temperature gradient at water-polymer interface, both polymer and water thermal conduct problems were founded and coupled at the interface. The finite element method was employed to solve the melt flow problem, and the finite difference method was used to discretize the energy equation. To verify the validity of the proposed model and algorithm, experiments were performed to measure the displacement of the water–melt interface for various melt temperatures and water pressures. The experimental results indicate that the primary penetration theory is not accurately on predicting residual wall thickness, whereas the combined primary and second penetration method significantly improve the accuracy.

Photoactivatable fluorophores and techniques for biological imaging applications

Photoactivatable fluorophores (PAFs) are powerful imaging probes for tracking molecular and cellular dynamics with high spatiotemporal resolution in biological systems. Recent developments in biological microscopy have raised new demands for engineering new PAFs with improved properties, such as high two photon excitation efficiency, reversibility, cellular delivery and targeting. Here we review the history and some of the recent developments in this area, emphasizing our efforts in developing a new class of caged coumarins and related imaging methods for studying dynamic cell-cell communication through gap junction channels, and in extending the application of these caged coumarins to new areas including spatiotemporal control of microRNA activity in vivo.

Hydrogen-rich saline alleviates experimental noise-induced hearing loss in guinea pigs

OBJECTIVE

To examine the efficiency of hydrogen-rich saline in the treatment of intensive noise-induced cochlear injury.

MATERIALS AND METHODS

Forty guinea pigs were assigned to one of four groups: HS+NOISE (i.p. injection hydrogen-rich saline), NS+NOISE (i.p. injection normal saline), NOISE ALONE (noise control), and NO TREATMENT (normal control) groups. The HS+NOISE, NS+NOISE, and NOISE ALONE groups were exposed to intensive noise (4 h at 115 dB SPL noise of 4000±100 Hz). The auditory brainstem response (ABR) was used to examine the hearing threshold in each group. Distortion product otoacoustic emission (DPOAE) was used to examine outer hair cell function. We also examined cochlear morphology to evaluate inner and outer hair cell trauma induced by noise exposure. Hydrogen-rich saline was administered twice daily for 6 days (2.5 ml/kg, i.p.) 24 h after noise exposure.

RESULTS

Baseline ABR thresholds and DPOAE values were normal in all groups at the measured frequencies (2, 4, 8, and 16 kHz) before noise exposure. The ABR threshold shift was 50-55 dB across the frequencies tested, and average DPOAE declined in the NOISE ALONE, NS+NOISE, and HS+NOISE groups 24 h after noise exposure. However, the changes in cochlear parameters were different between groups. The HS+NOISE group showed a significantly decreased ABR threshold value as compared with the NS+NOISE or NOISE ALONE group (P<0.01) on day 7. The mean DPOAE recovered to some extent in the three noise exposure groups, but at most frequencies the HS+NOISE group showed significantly increased DPOAE on day 7 as compared with the NS+NOISE group or NOISE ALONE group (P<0.01). Surface Corti organ preparations stained with succinate dehydrogenase (SDH) showed that most outer hair cells (OHCs) were still dropsical and a few were missing 7 days after noise exposure in the NS+NOISE group. Only a few OHCs were slightly dropsical in the HS+NOISE group. The numbers of missing hair cells 7 days after noise exposure were significantly greater in the NOISE ONLY and NS+NOISE groups than the HS+NOISE group (P<0.01).

CONCLUSIONS

Hydrogen-rich saline can alleviate experimental noise-induced hearing loss in guinea pigs, partially by preventing the death of cochlear hair cells after intensive noise exposure.

Temporal and spatial regulation of microRNA activity with photoactivatable cantimirs

MicroRNAs (miRNAs) are small non-coding RNAs that play numerous important roles in physiology and human diseases. During animal development, many miRNAs are expressed continuously from early embryos throughout adults, yet it is unclear whether these miRNAs are actually required at all the stages of development. Current techniques of manipulating microRNA function lack the required spatial and temporal resolution to adequately address the functionality of a given microRNA at a specific time or at single-cell resolution. To examine stage- or cell-specific function of miRNA during development and to achieve precise control of miRNA activity, we have developed photoactivatable antisense oligonucleotides against miRNAs. These caged oligonucleotides can be activated with 365 nm light with extraordinarily high efficiency to release potent antisense reagents to inhibit miRNAs. Initial application of these caged antimirs in a model organism (C. elegans) revealed that the activity of a miRNA (lsy-6) is required specifically around the comma stage during embryonic development to control a left/right asymmetric differentiation program in the C. elegans nervous system. This suggests that a transient input of lsy-6 during development is sufficient to specify the neuronal cell fate.