Bio-Medical Materials and Engineering - Volume 33, issue 4
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Bio-Medical Materials and Engineering is to promote the welfare of humans and to help them keep healthy. This international journal is an interdisciplinary journal that publishes original research papers, review articles and brief notes on materials and engineering for biological and medical systems.
Articles in this peer-reviewed journal cover a wide range of topics, including, but not limited to: Engineering as applied to improving diagnosis, therapy, and prevention of disease and injury, and better substitutes for damaged or disabled human organs; Studies of biomaterial interactions with the human body, bio-compatibility, interfacial and interaction problems; Biomechanical behavior under biological and/or medical conditions; Mechanical and biological properties of membrane biomaterials; Cellular and tissue engineering, physiological, biophysical, biochemical bioengineering aspects; Implant failure fields and degradation of implants. Biomimetics engineering and materials including system analysis as supporter for aged people and as rehabilitation; Bioengineering and materials technology as applied to the decontamination against environmental problems; Biosensors, bioreactors, bioprocess instrumentation and control system; Application to food engineering; Standardization problems on biomaterials and related products; Assessment of reliability and safety of biomedical materials and man-machine systems; and Product liability of biomaterials and related products.
Abstract: BACKGROUND: Polymerization stress is a major problem in dental resin composite restorations. Two indentation fracture methods can be applied to evaluate the stress, however, they often calculate different values. OBJECTIVE: To compare polymerization stresses of dental composites determined by the two methods. METHODS: Glass disks with a central hole were used. Two indentation fracture methods (Methods 1 and 2) were employed to determine the polymerization stresses of low-shrinkage and bulk-fill composites. Method 1: Cracks were made in the glass surface at 300 μm from the hole. The hole was filled with the composite. Polymerization stresses at 30 min after filling were…calculated from the lengths of crack extension. Method 2: The hole was filled with the composite. Cracks were introduced in the glass at 1,000 μm from the hole at 30 min after the polymerization and the stresses were calculated from the crack lengths. Stresses at composite-glass bonded interface were calculated from the stress values obtained by the two methods. RESULTS: The bulk-fill composite generated the smallest interfacial stress, and Method 1 revealed lower values than Method 2. CONCLUSIONS: The composites yielded relatively small stresses. Method 1 calculated smaller stress values, possibly affected by the lower threshold stress intensity factor.
Abstract: BACKGROUND: In stem cell therapy, due to the lack of an effective carrier, a large number of transplanted stem cells are lost and die. Therefore, finding a suitable carrier has become a further direction of stem cell therapy. OBJECTIVE: In research on the co-culture of polycaprolactone (PCL) with 1,1′ -Dioctadecyl-3,3,3′ ,3′ - tetramethylindocarbocyanine perchlorate (DiI) labeled bone marrow mesenchymal stem cells (BMSCs), we observe the effect of materials on the growth and proliferation of DiI labeled stem cells, and the effect of DiI labeling on patch preparation, so as to find a kind of biomaterial…suitable for the growth and proliferation of BMSCs, and find a suitable cell carrier for stem cell therapy of myocardial infarction and in vivo tracing. METHODS: Clean grade Sprague Dawley rats were selected as experimental objects, BMSCs were isolated and cultured, and the surface markers were identified by flow cytometry. After the BMSCs were cultured for 3 passages, the BMSCs were stained with DiI dye, and the BMSCs DiI and PCL biomaterial film were co-cultured. After 24 hours, the cell growth was observed under fluorescence microscope, and fixed for scanning under electron microscope. The cell proliferation was detected by CCK-8 at 1, 4, 7, 10 days of culture. The measurement data conforming to normal distribution are expressed in the form of mean ± standard deviation (X ¯ ± s ). One way ANOVA was used for comparison among groups, LSD analysis was used for pairwise comparison. The difference was statistically significant (P < 0.05). RESULTS: BMSCs were strongly positive for CD90, CD44H, but negative for CD11b/c, CD45. Under fluorescence microscope, BMSCs DiI showed red light, fusiform or polygonal. Under the scanning electron microscope, the cell patch formed by co-culture of PCL film and DiI-BMSCs had a large number of cells on the surface and normal cell state. CCK-8 assay showed that the OD value on the first day was 0.330 ± 0.025; The OD value was 0.620 ± 0.012 on the 4th day, 1.033 ± 0.144 on the 7th day and 1.223 ± 0.133 on the 10th day. There was significant difference among the time points (P < 0.05). CONCLUSIONS: The cell patch made of PCL film and DiI labeled BMSCs can survive and proliferate on the surface, so it can be used as a scaffold material for stem cell therapy in vivo.
Abstract: BACKGROUND: Femoral neck fracture is an unsolved challenge in orthopedics. The complication rate in particular is high. There remains a lack of consensus on the optimal choice of internal fixation for unstable femoral neck fracture. OBJECTIVE: The study aimed to develop a new headless compression supporting screw (HCSS) for the treatment of unstable foemoral neck fracture. METHODS: We designed a new HCSS and used a femoral neck fracture (Pauwels III fracture) model (left, fourth-generation composite, Sawbones) and three-dimensional finite element analysis to compare the biomechanical performance of HCSSs with that of cannulated compression screws (CCSs) for…treatment of unstable femoral neck fracture. RESULTS: Maximum displacement, peak von Mises stress, peak strain, and rotation for the HCSS were smaller than those for the CCS. The stress was more widely distributed for the HCSS, whereas the stress was concentrated for the CCS. CONCLUSIONS: The HCSS resulted in better biomechanical stability than that from the CCS. For Pauwels III fractures the HCSS exhibits better resistance to shear forces and better support, providing a new clinical treatment.
Keywords: Femoral neck fracture, Pauwels III, fracture finite element analysis, cannulated compression screw, headless compression support screw
Abstract: BACKGROUND: The knee plays an essential role in movement. There are four major ligaments in the knee which all have crucial functionalities for human activities. The anterior cruciate ligament (ACL) is the most commonly injured ligament in the knee, especially in athletes. OBJECTIVE: The aim of this study was to investigate the dynamic tensile response of the porcine ACL at strain rates from 800 to 1500 s−1 for simulations of acute injury from sudden impact or collision. METHODS: Split Hopkinson Tension Bar (SHTB) was utilized to create a dynamic tensile wave on the ACL. Stress–strain…curves of strain rates between 800 s−1 to 1500 s−1 were recorded. RESULTS: The results demonstrated that the elastic modulus of the porcine ACL at higher strain rates was six to eight times higher than that of porcine and human specimens at quasi-static strain rate. However, the failure stress was quite similar while the strain was much smaller than that at the lower strain rate. CONCLUSIONS: ACL is highly strain rate sensitive and easier to break with lower failure strain when the strain rates increased to more than 1000 s−1 . The stress–strain curves indicated that the sketching crimps at the slack region did not happen but switched to the sliding process of collagen fibers and was accompanied by some ruptures, which can develop into tears when strain and stress were large enough. On the other hand, the viscoelastic properties of the ligament, depending on the proteoglycan matrix and the cross-link, showed a limited value in the studied strain rate range.
Abstract: BACKGROUND: Obesity and leptin deficiency are associated with compromised bone regeneration. OBJECTIVE: This study aims to investigate the role of locally administrated low-dose BMP2+leptin on bone regeneration in leptin-deficient obese (ob/ob ) mice. METHODS: Wildtype (WT) and ob/ob mice were divided into 3 groups (4 mice/group): BMP2 (5 μg) group, BMP2+low-dose leptin (1 μg) group, and BMP2+high-dose leptin (2.5 μg) group. WT mice were used as control mice. An equal size absorbable collagen sponge was prepared by loading the BMP2 or/and leptin and implanted subcutaneously. After 19 days, samples were collected and analyzed by micro-CT and H&E staining.…RESULTS: No significant difference in bone regeneration among the three groups in WT mice. Quantification of newly formed bone parameters from micro-CT and H&E staining showed that low-dose BMP2 treatment formed less new bone in ob/ob mice compared to WT. BMP2+low-dose leptin treatment substantially rescued the compromised bone regeneration in ob/ob mice up to the level in WT mice. However, the BMP2 and high dose of leptin failed to rescue the compromised bone regeneration in ob/ob mice. CONCLUSION: Our findings suggest that a combination of the low-dose BMP2 and leptin could be a strategy to promote osteogenesis in obese populations with leptin deficiency.
Keywords: Leptin deficiency, osteogenesis, bone morphogenetic protein-2 (BMP2), ob/ob mice
Abstract: BACKGROUND: There is currently no methodology for evaluating the accuracy of ablation in ablation therapy, and thus normal cells in the surrounding area can be damaged, possibly leading to complications. OBJECTIVE: The aim of this study was to distinguish heat-treated dead cells from viable cells using the electrical impedance-to-frequency ratio as an evaluation index. METHODS: Rat heart striated myocytes were cultured in a monolayer on collagen-coated microelectrodes placed in the center of an electrode-loaded chamber. The cells in the chamber were killed by heat treatment for 5 minutes at 50 °C, and the frequency response of…the cell impedance was measured before and after heat treatment. The frequency of the input current was varied from 10 to 100 kHz. The measured electrical impedance at each frequency was divided by the value at 100 kHz, and we refer to the resulting values as the impedance ratio. RESULTS: The impedance ratio was high at low frequencies and low at high frequencies. Furthermore, the impedance ratio was lower at lower frequencies after heat treatment than before heat treatment. CONCLUSIONS: The electrical impedance ratio can be used to distinguish viable and dead cells after heat treatment.
Keywords: Distinction of cell survival, frequency dependence of electrical impedance, heat-treated cell
Abstract: BACKGROUND: Within the scope of minimally invasive dentistry, the use of different biocompatible remineralization agents on incisors affected by molar-incisor hypomineralization (MIH) gains importance. OBJECTIVE: To evaluate the effect of casein phosphopeptide amorphous calcium fluoride phosphate (CPP-ACFP) and calcium glycerophosphate (CaGP) in mineral density (MD) of white/creamy and yellow/brown demarcated opacities on incisors affected by MIH by means laser fluorescence (LF). METHODS: As a cross-over, randomized trial, twenty-two children with 167 incisors affected by MIH were recruited and randomly assigned to one of the two different agents and crossed over to other agents with two…weeks washout in between. Incisors were examined by using LF at all before and after three months periods. RESULTS: The results of the paired t -tests for determining the period effect between the baseline findings showed significant difference in white/creamy and yellow/brown demarcated opacities of LF values for both groups (p < 0.05). The difference between both groups according to after categorization of 20% increasing in MD in the percent of change before and after application on LF values; was not found statistically significant in white/creamy (p = 0.970) and yellow/brown (p = 0.948) opacities. CONCLUSIONS: The primary outcome was CPP-ACFP and CaGP had a positive effect in decreasing hypomineralization on MIH-affected enamel for three months period.