Static and gait finite element analysis on individualized titanium alloy pelvic prosthesis manufactured by 3D printing / 医用生物力学

Objective To evaluate the biomechanical properties of 3D printed individualized titanium alloy pelvic prosthesis in static and gait states by the method of finite element analysis. Methods Three patients with different types of pelvic tumors were treated by hemi-pelvic arthroplasty with resection of hemi-pelvis. CT and MRI were performed before the surgery, and the corresponding individualized titanium alloy pelvic prostheses were designed. The pelvic models were reconstructed with 3D reconstruction technique, and then assembled with the individualized pelvic prostheses. The human skeletal muscle model was established by AnyBody software to perform gait dynamics analysis. The stress distribution and stress concentration areas of 3 reconstructed pelvic models in static and gait states were obtained by ABAQUS. Results Under both static and gait conditions, the maximum stress of the 3 pelvic prostheses was smaller than the yield strength of the titanium alloy. The pelvic ring of the reconstructed pelvis could meet the rule of stress conduction. The patients’ daily life returned to normal condition after the surgery. Conclusions The effect of 3D prosthetic titanium prosthesis on recovery of pelvic ring is satisfactory, and its effectiveness and stability can meet the requirement of human biomechanics. The analytic results can provide references for clinicians and prosthesis designers.

Static and gait finite element analysis on individualized titanium alloy pelvic prosthesis manufactured by 3D printing / 医用生物力学

Objective To evaluate the biomechanical properties of 3 D printed individualized titanium alloy pelvicprosthesis in static and gait states by the method of finite element analysis.Methods Three patients with different types of pelvic tumors were treated by hemi-pelvic arthroplasty with resection of hemi-pelvis.CT and MRI were performed before the surgery,and the corresponding individualized titanium alloy pelvic prostheses were designed.The pelvic models were reconstructed with 3D reconstruction technique,and then assembled with the individualized pelvic prostheses.The human skeletal muscle model was established by AnyBody software to perform gait dynamics analysis.The stress distribution and stress concentration areas of 3 reconstructed pelvic models in static and gait states were obtained by ABAQUS.Results Under both static and gait conditions,the maximum stress of the 3 pelvic prostheses was smaller than the yield strength of the titanium alloy.The pelvic ring of the reconstructed pelvis could meet the rule of stress conduction.The patients' daily life returned to normal condition after the surgery.Conclusions The effect of 3D prosthetic titanium prosthesis on recovery of pelvic ring is satisfactory,and its effectiveness and stability can meet the requirement of human biomechanics.The analytic results can provide references for clinicians and prosthesis designers.

Biomechanical analysis and reasoning on aseptic loosening failure after total hip arthroplasty / 医用生物力学

Objective To propose some detailed methods for diagnosis of aseptic loosening failure in clinic by studying the mechanical mechanism and the specific causes of aseptic loosening failure after the total hip arthroplasty (THA). Methods The causes of aseptic loosening were investigated from the view of biomechanics, such as strength of the bone cement layer, interface fretting, stress shielding, wear and osteolysis; the relationships between aseptic loosening failure and products, clinical and patient factors were analyzed; the method to detect loosening before the revision surgery was also studied. Results The reasoning route for aseptic loosening failure analysis after THA was proposed, and detection of aseptic loosening with fluoroscopic analysis (FSA) technique before the revision surgery was conducted successfully. Conclusions The reasoning route for aseptic loosening failure analysis can help to discover reasons of failure occurrence. Loosening can be detected and confirmed in vivo by FSA method, which can also assist the clinician for diagnosis and treatment of aseptic loosening after the THA.

Study of mtDNA 12S rRNA A1555G, GJB2, GJB3 gene mutation in Uighur and Han people with hereditary nonsyndromic hearing loss in Xinjiang / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To study mtDNA, GJB2, GJB3 and determine gene mutation situs and frequency in Uighur and Han people with hereditary nonsyndromic hearing loss, and to compare the differences of gene mutation situs and frequency between Uighur and Han people.</p><p><b>METHODS</b>Blood samples were obtained from 93 patients (43 Uygur and 50 Han) with hereditary non-syndromic hearing loss and 110 normal people (56 Uygur and 54 Han). Genomic DNA was extracted from isolated leukocytes, and amplified by polymerase chain reaction (PCR). PCR products of GJB3 were sequenced directly; while PCR products of mitochondrial DNA 12S rRNA A1555G point mutations were analyzed by PCR-Alw26I digestion, and positive ones were further sequenced. GJB2 genes of 83 patients (43 Uygur and 40 Han) with hereditary non-syndromic hearing loss and 98 normal people (46 Uygur and 52 Han) were directly sequenced.</p><p><b>RESULTS</b>Among GJB3 genes of 93 patients, 2 cases of 33C-T, 2 cases of of 766G-A, 7 cases of 357C-T, and 4 cases of 798C-T were detected. Mitochondrial DNA 12SrRNA A1555G mutation was detected in 8 patients (2 Uygur and 6 Han). Nine kinds of base changes of GJB2 were detected: 109G-A, 233-235delC, 79G-A, 196G-A, 341A-G, 564G-A, 380G-A, 71G-A, and 35delG. In the control group, detected GJB3 mutations included 4 cases of 357C-T, 5 cases of 798C-T, and 2 cases of 93C-T; while 9 kinds of base changes of GJB2 were detected: 341A-G, 380G-A, 457G-A, 79-GA, 109G-A, 281A-G, 21G-T, 171G-T, and 368C-A. For mtDNA 12SrRNA A1555G, the difference between study group of and control group of Han people was statistically significant (P < 0.05). For GJB2 mutation 79G-A, the difference between study group and control group was statistically significant (P < 0.05) in both Uygur and Han people; while for GJB2 mutation 341A-G, the difference in study group between Uygur and Han people was statistically significant (P < 0.05). And for GJB3 mutation 798C-T, the difference was statistically significant both between study group and control group, and between Uygur and Han people (P < 0.05).</p><p><b>CONCLUSIONS</b>In Xinjiang, mutation rate was high for mtDNA 12SRNA A1555G. while GJB3 gene mutations were not the main cause of the hereditary nonsyndromic hearing loss. There were certain ethnic and geographical characteristics of GJB2and GJB3 mutations.</p>

[Factors of avascular necrosis of femoral head and osteoporosis in SARS patients' convalescence].

OBJECTIVE: To explore the factors affecting the pathogenesis of avascular necrosis of femoral head and osteoporosis of SARS patients during convalescent stage. METHODS: The clinical data of 40 SARS patients, 12 males and 28 females, aged 29 +/- 9, hospitalized from April to June 2003, were reviewed, targeted on the use of glucocorticoids. Three months after the discharge ELISA and indirect immunofluorescent antibody (IFA) assay were used to detect the serum IgG. Magnetic resonance imaging (MRI) was used to detect the damage of the head of femur and quantitative ultrasound (QUS) was used to detect osteoporosis at the left heel. RESULTS: The average total dosage of methylprednisolone was (4949 +/- 2959) mg, and the average course of treatment was (24 +/- 5) days (16 to 30 days). Twenty-three patients underwent ictus therapy of corticosteroids for (8 +/- 4) days. The extenuation time of corticosteroid' dosage was (33 +/- 26) mg/d. Of the 40 patients, 36 were IgG positive with an average A value of (0.91 +/- 0.24) and 4 patients were IgG negative. Twelve patients (30%) were with type I avascular necrosis of femoral head, including 3 cases with unilateral left--necrosis and 9 cases of bilateral necrosis. The other 28 patients were without necrosis. Two patients were suffering from osteoporosis and 30 patients were with bone density decrement. The average Z values of the parameter BUA and VOS were (-1.26 +/- 0. 53) and (-0.53 +/- 0.30) respectively. The corresponding T values of the parameter BUA and VOS were (-1.49 +/- 0.59) and (-0.65 +/- 0.05) respectively. The influencing factors of femoral necrosis included the degree of healing activity, the dosage summation of corticosteroids, and length of ictus therapy. The influencing factors of bone density included age, dosage summation, and length of ictus therapy. The influencing factors of the bone fabric and flexibility included the use and length of ictus therapy. Statistics showed that serum IgG was not related with avascular necrosis of femoral head and osteoporosis. CONCLUSIONS: The incidence rates of avascular necrosis of femoral head and of osteoporosis were higher in convalescent SARS patients than in general population. The influencing factors of femoral necrosis included the degree of healing activity, the dosage summation of corticosteroids, and length of ictus therapy. The influencing factors of bone density included age, dosage summation, and length of ictus therapy. The influencing factors of the bone fabric and flexibility included the use and length of ictus therapy. Statistics showed that serum IgG was not related with avascular necrosis of femoral head and osteoporosis. SARS virus may not affect the pathogenesis of avascular necrosis of femoral head and osteoporosis.

[Analysis of relation between the usage of corticosteroid in treatment and arthralgia as a sequela of SARS patients].

OBJECTIVE: To analyze relation between the use of corticosteroids in the treatment for severe acute respiratory syndrome (SARS) patients and arthralgia as a sequela. METHODS: Clinical date of 30 SARS patients without other diseases in whom corticosteroid was used were reviewed including total dosage, duration of use, the highest dosage and its duration, and speed of reduction in dosage. The information about arthralgia was investigated one month after discharge of SARS patients from the hospital. RESULTS: The average total dosage of methylprednisolone was (4 244.16+/-2 292.30) mg, and the duration of use of the treatment was (25.36+/-5.88) days (ranging from 12 to 35 days). The maximum dosage was (321.33+/-174.03) mg/d, and the duration of its use was (7.73+/-4.08) days. The speed of reduction of dosage of corticosteroids was (21.33+/-10.18) mg/d. There were 26 of 30 patients (86.67 percent) experienced arthralgia symptom during convalescence. In 3.6 percent of patients arthralgia occurred within one month after SARS, 53.85 percent of the patients experienced low-grade arthralgia. By unifactor analysis, the total dosage and its duration of use, the highest dosage and its duration, speed of reduction of dosage of corticosteroids were correlated with the degree of arthralgia, respectively. The duration of arthralgia was correlated with the total dosage, the duration of high dosage, and high dosage. Age was not correlated with either the degree or the persisting time of arthralgia. The degree of arthralgia was only correlated with the total dosage, and the duration of arthralgia was correlated with administration time of glucocorticosteroids by multifactor analysis. CONCLUSION: There is a dosage- effect relation between the degree of arthralgia and the total dosage of corticosteroid, and a time-effect relation between the duration of arthralgia and length of the use of corticosteroids.

The effect of long-term culture in vitro on biological characteristics of human adipose tissue derived stem cells / 中华创伤骨科杂志

Objective To observe the effect of lnng-term in vitro culture on the biological properties of adipose-derived stem cells(ADSCs)as seeding cells of tissue engineering.Methods The surface makers and apoptosis of primary and passaged human ADSCs were identified by flow cytometric analysis.Osteogenic differentiation of ADSCs at different passages were identified by alkaline phosphatase(ALP),Von Kossa staining and RT-PCR respectively.Results The surface marker expression of mesenchymal stem cells on ADSCs was high and did not change with passages of the cells.The early apoptosis rate of the cells was 1% to 2%,and increased insignificantly from passage one to passage nine.The osteogenic potential of ADSCs confirmed by ALP,Von Kossa staining and RT-PCR was maintained to as late as passage eight.Conclusion Since the biological properties of ADSCs are stable,they can be served as optimal seeding cells for tissue engineering and regenerative research.

Advances in clinical diagnosis and treatment of severe acute respiratory syndrome.

It has been proved that severe acute respiratory syndrome (SARS) is caused by SARS-associated coronavirus, a novel coronavirus. SARS originated in Guangdong Province, the People's Republic of China at the end of 2002. At present, it has spread to more than 33 countries or regions all over the world and affected 8 360 people and killed 764 by May 31,2003. Identification of the SARS causative agent and development of a diagnostic test are important. Detecting disease in its early stage, understanding its pathways of transmission and implementing specific prevention measures for the disease are dependent upon swift progress. Due to the efforts of the WHO-led network of laboratories testing for SARS, tests for the novel coronavirus have been developed with unprecedented speed. The genome sequence reveals that this coronavirus is only moderately related to other known coronaviruses. WHO established the definitions of suspected and confirmed and probable cases. But the laboratory tests and definitions are limited. Until now, the primary measures included isolation, ribavirin and corticosteroid therapy, mechanical ventilation, etc. Other therapies such as convalescent plasma are being explored. It is necessary to find more effective therapy. There still are many problems to be solved in the course of conquering SARS.

Osteogenic potential of hBMP-2 gene transduced human adipose-derived stem cells / 中华创伤杂志

Objective To investigate the ostengenie potential of adipose-derived stem cells(AD- SCs)when exposed to adenovirns containing hBMP-2 cDNA(Adv-hBMP-2)and offer a choice of cell source for gene therapy and tissue engineering.Methods Human adipose tissues were obtained from patients who received orthopaedic surgery or liposuction.ADSCs were obtained by digesting the adipose tissues.Firstly,flowcytometric analysis was performed for the confirmation of mesenchymal stem cell ori- gin and the surface markers including CD34,CD44,CD68,CD71,CD90,and CD105.The ADSCs were transfected by Adv-hBMP-2 and the effects were tested in vitro,lmmunoprecipitation and Western blotting and ELISA were performed for confirming BMP gone transduction and its stable expression.The transform of ADSCs was assessed by extracellular ALP staining,intracellular ALP spectrophotometry,von Kossa staining and RT-PCR.In the in vivo experiment ADSC-Adv-hBMP-2 cells were injected into the hind limb of nude mice and analyzed radiographically and histologically.Results ADSCs were successfully isolated from human adipose tissues.The isolated ADSCs expressed CD44,CD71,CD90 and CD105 and CD34 and CD68 were absent.The result confirmed the mesenchymal stem cell origin of the cells.West- ern blotting and ELISA confirmed successful and persistent hBMP-2 production by ADSC-Adv-hBMP-2 cells.Extracellular ALP staining,intracellular ALP spectrophotometry,yon Kossa staining and RT-PCR revealed that ADSCs treated with Adv-hBMP-2 had a tendency of transfering into osteoblast.X-ray and H&E sections from hind limb of nude mice injected with ADSC-Adv-hBMP-2 cells confirmed bone forma- tion at 2 weeks.Conclusions Liposuction aspirates contain abundant ADSCs that can be transduced with hBMP-2 gene,and the tranduced ADSCs differentiate into the osteoblast.ADSCs may be an ideal source of mesenchyme-lineage stem cells for gone therapy and tissue engineering.