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A method for measuring 13C isotopic abundance of intracellular metabolites of Saccharopolysporaerythraea by ultra-high performance liquid chromatography (UPLC)-triple quadrupole mass spectrometry was established.First, the chromatographic conditions of UPLC were optimized, and then the MS conditions such as unique tube lens voltage, collision energy, and ion pair were optimized.On the bases of length of the parent and daughter ions carbon chains and whether the daughter ions contain 13C atoms, the one-to-one method, one-to-many method and SIM method were established for measuring 13C isotopic abundance.Then these methods were used to measure naturally labeled intracellular metabolite standards and 13C labeled samples, and according to the gap between the experimental value and the theoretical value, the best method was established for each metabolite of different characteristics.The results showed that one-to-one method was most effective for measuring the metabolites of daughter ions not containing 13C atoms represented by sugar phosphates, one-to-many method was the best for measuring the metabolites of both parent and daughter ions containing 13C short carbon chains represented by carboxylic acids, SIM method could play a role in measuring the metabolites of both parent and daughter ions containing 13C long carbon chains represented by coenzyme A.This method had a good measurement precision and could be applied to the measurement of Saccharopolysporaerythraea intracellular metabolites, which contributed to the consequent study of metabolic mechanism and the efficient expression of erythromycin.
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BACKGROUND:Silk fibroin, as an inorganic mineralization template, can induce hydroxyapatite crystal growth, and combined with nano-hydroxyapatite can simulate the inorganic and organic components of natural bone, which is expected to become the most ideal bone graft material. OBJECTIVE:To prepare the silk fibroin/nano-hydroxyapatite composite material and investigate its treatment outcomes in spinal fusion. METHODS:Silk fibroin/nano-hydroxyapatite composite was synthesized by the co precipitation method with silk fibroin and calcium phosphate as raw materials, to simulate the structure and composition of the bone tissue. The crystal phase composition and microstructure of the composite scaffold were analyzed by X-ray diffraction and transmission electron microscope. Osteoblasts were seeded onto the composite, and the cel adhesion and proliferation were observed under inverted microscope. The lumbar posterolateral spinal fusion models were established in the New Zealand rabbits, fol owed by treated with autologous bone graft (control group) and composite (composite group), respectively. The gross, radiological and histological observations of bone fusion were compared between groups. RESULTS AND CONCLUSION:Silk fibroin/nano-hydroxyapatite composite appeared to be fascicular under electron microscope, the length was 200-500 nm and width was 20-30 nm. And the hydroxyapatite was about 200 nm in length and 50 nm in width. X-ray diffraction showed that the bottom of diffraction peak was wide, and the peak was not sharp. Transmission electron microscope found that cel s adhered wel onto the composite scaffold at 2 days. Scanning electron microscope showed that the polygonal, oval or conical cel s covered most of the composite scaffold holes, presented obvious mitotic phase at 5 days. The third generation of MC3T3-E cel s tended to rise at first 3 days, and then decreased. The fusion site of L5-6 transverse process was strong, and non-bony fusion occurred. At the same time, numerous new bones were visible in the composite group. Hematoxylin-eosin staining showed a large number of cel aggregation, abundant osteoblasts surrounding cartilage, and the bone tissues were in a regular arrangement in the composite group. Moreover, irregular trabecular bone with medul ary cavity was found in the composite material. These results suggest that the silk fibroin/nano-hydroxyapatite composite with the similar structure and composition of natural bone can achieve satisfactory fusion effect in the rabbit lumbar posterolateral fusion.
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BACKGROUND:Although the traditional surgical treatment can improve the symptoms of patients with senile osteoporotic vertebral fracture, the treatment easily produces bone graft fusion failure and pseudoarticulation formation and affects clinical effects. OBJECTIVE:To investigate biomechanical properties of anterior cervical pedicle screw and the effects on osteoporotic vertebral stability. METHODS:A total of 16 fresh cadaver cervical specimens contained 64 motion segments (C3-4, C4-5, C5-6 and C6-7). The 64 segments by the way of implantation were randomly divided into ordinary anterior locking screw fixation group and lower anterior vertebral pedicle screw system group (32 segments per group). The mechanical properties were determined on the biomechanical testing machine for each group. RESULTS AND CONCLUSION:(1) Biomechanics:Compared with the ordinary anterior locking screw fixation group, the maximum pul-out strength, screw path length, postoperative vertebral column height, the maximum surface strain, strain maximum and the range of maximum values were increased in the lower anterior vertebral pedicle screw system group (P<0.05). (2) Results suggest that compared with the ordinary anterior locking screw fixation group, lower cervical anterior pedicle screw required larger extraction force and was more stable for osteoporotic vertebrae.
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13 C isotopic abundance of intracellular free amino acid with a characteristic of fast- turnover can quickly reflect changes in intracellular metabolic state. But the concentration of intracellular free amino acid is low, the existed 13 C isotope detection method based on GC-MS can not satisfy the requirement with full scan mode. In this study, the selected ion monitoring method was used to detect accuracy higher likelihood of analysis of 13 C isotopic abundance of free intracellular amino acid. First, in the full scan mode we analyzed of the fracture law of different amino acids, found the feature corresponding to each amino acid fragments, and established 16 kinds of free intracellular amino acids characteristic fragment library. Then using this characteristic fragment library, only specific m/z signal was detected in sample analysis, which realized the selected ion monitoring and improved the quality of signal. The results of amino acid standards showed that the signal-to-noise ratio, measurement precision and accuracy were improved by 17, 2. 0 and 3. 8 times compared with the full scan mode. In the analysis of coenzyme Q10 producing strains of samples, this method was successfully used to detect isotopic abundance of 8 kinds of free intracellular amino acids. This method plays an important role in the detection of 13 C isotopic abundance of the intracellular free amino acid in cell metabolism research.
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We inserted the 0.6 mm caliber graft-heparin (in inner wall) conduits into the tailarteries of 14 mice. The results showed that the graft conduit could be used repeatedly with no blood oozing out in the wound, no massive internal hemorrhage, and no additional coagulative reagent given during the whole experiment. On the other hand, the graft-heparin conduits of variant caliber were inserted into the femur arteries of 4 rabbits and 4 dogs for blood pressure experiment and femur arterio-venous bypass tests. The results showed that the anticoagulative effect of these conduits was markedly improved, but there was a strip of thrombus. There was no thrombus track in the wall of the conduit. The strip of thrombus was formed first in the cone of conduit where caliber changed. The results indicate that the blood flow resistance is in inverse proportion to 4 power of the conduit radius. So the thinner the conduit is, the more sensitive to conduit radius variation the conduit resistance will be. In studying and making the arfificial conduit, one must take notice of the conduit caliber, which should be equal to the caliber of the blood vessel.
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Animals , Dogs , Mice , Rabbits , Anticoagulants , Blood Vessel Prosthesis , Heparin , Regional Blood FlowABSTRACT
Objective:To establish a precise three-dimensional finite element model of temporomandibular joint.Methods: On the basis of images of Chinese Visible Human, the reverse engineering technology was applied to reconstruct the Computer Aided Design(CAD) model of temporomandibular joint.Afterwards, the model was established. Results:A three-dimensional finite element model consisting of 66 122 nodes and 212 704 elements of temporomandibular joint including cortical bone, cancellous bone, mandibular dental arch, masticatory muscles, articular cartilage and periodontal ligament was constructed. Conclusion:The finite element model is more efficient and more precise.