Objective To explore the effects of changes in the length of the patella on patellofemoral contact areas and pressures, to provide a theoretical foundation for treatment of lower pole of patella fracture. Methods Using homemadeloadingequipment, pressure sensitive films of 100 mm × 100 mm in size were placed on the force platform, vertically downwardload (0-19.6 N) was given. The pressure-sensitive response curve was obtained by computer image analysis of the pressuresensitive tablets and calculation. Six male left fresh knee specimens from voluntary donation were placed in homemade-test fixed load device, and the double-layer pressure sensitive film was placed on the patellofemoral joint surface; under loading of 196 N at flexion of 0, 15, 30, 45, 60, 75, 90, 105, 120, and 135° for 2 minutes, respectively, the pressure sensitive film was removed as the control group. Patellas were transected cut and in situ fixed by Kirschner wire and steel-wire as in situ fixation group. Bone fragments obtained from the corresponding 1/6 and 2/6 of contralateral patella, were embedded in the interspace between osteotomy with internal fixation with Kirschner wire and steel-wire respectively as lengthening group. Followed by the amputating patella length of 1/6, 2/6, 3/6 from proximal to distal and internal fixation with Kirschner wire and steel wire by turns as a shortening group. Repeat the above steps of each experiment. By image analysis the pressure sensitive film, the patella joint contact area were measured, and patellar contact pressure (including the peak pressure and average pressure) was calculated according to pressure-sensitive response curve. Results The actural contact area were significantly smaller in the shortening groups than in the control group at flexion of 30-135° (P lt; 0.05); the pressure was significantly bigger in shortening 1/6 group at flexion of 0, 15, 60, and 75°, in shortening 2/6 group at flexion of 0° and 75-135°, and in shortening 3/6 group at flexion of 0-30°and 75-135° than in the control group (P lt; 0.05); the peak pressure was significantly bigger in shortening 1/6 group at flexion of0, 15, and 60-105°, in shortening 2/6 group at flexion of 0, 15, and 75-105°, and in shortening 3/6 group at flexion of 0, 30, and 60-135° than in the control group (P lt; 0.05). The actural contact area was significantly smaller in the lengthening groups than in the control group at flexion of 15, 60, and 90°, and it was bigger at flexion of 105, 135° in lengthening 2/6 group than in the control group (P lt; 0.05); the pressure was significantly bigger in the lengthening groups at flexion of 15-75° than in the control group and it was smaller in the lengthening groups at flexion of 105, 135°, and smaller in lengthening 2/6 group at flexion of 120° (P lt; 0.05); the peak pressure was significantly smaller in lengthening 1/6 group than in the control group at flexion of 0, 90, and 105° and smaller in lengthening 2/6 group at flexion of 0° (P lt; 0.05). The actural contact area was significantly bigger in all lengthening groups than in all shortening groups at flexion of 30, 45, and 75-135° (P lt; 0.05). The pressure was significantly bigger in shortening 1/6 group than in lengthening groups at flexion of 0, 60, and 90° (P lt; 0.05), in shortening 2/6 group at flexion of 0, 60, and 90-120° (P lt; 0.05), in shortening 3/6 group at flexion of 0-135° (P lt; 0.05). The peak pressure was bigger in shortening groups than in lengthening 1/6 group at flexion of 0, 90, and 105° (P lt; 0.05), bigger than lengthening 2/6 group at flexion of 0° (P lt;0.05余请见正文.....
Objective To examine the expression of proliferating cell nuclear antigen (PCNA) of retinal pigment epithelial (RPE) cells, thus assessing the role of mechanism of contact inhibition playing in the process of experimental retinal detachment and reattachemnt.Methods Retinal detachment was produced in 72 cats by subretinal injection of 0.25% solution of healon through a micropipette three weeks after extracapsular lens extraction and vitrectomy. Some of the detached retinae were reattached 24 hours later. At different time, the cats were killed and eye globes were fixed and embeded in paraffin. Histologic sections were processed for immunohistochemistry examination using an antibody to detect PCNA protein. Labeled RPE cells were identified, and the proliferation was quantified in detached and un-detached retinae of detachment group, and also in reattached retinae of reattachment group. The comparsion of PCNA-labeled RPE cells in different groups were analyzed by ANOVA. Results In detached regions of detachment group, PCNA-expression of RPE cells occured within 24 hours, and reached a maximum after 5-6 days, then gradually declined to barely detectable levels after 20 days. Similar tendency was found in reattached retinae, but the number of PCNA-labeled RPE cells was obviously small. Fewer PCNA-labeled RPE cells were found in regions of un-detached retinae in detachment group. The difference of these three groups was significant.Conclusion Proliferation of RPE cells is induced when they lose contact with neural retina, but inhibited after neural retina reattached to RPE cells. It suggests that the mechanism of contact inhibition plays a role in the proliferative process after retinal detachment and reattachment. (Chin J Ocul Fundus Dis，2003，19：20-23)
ObjectiveTo investigate the expressions of contactin-1 (CNTN-1), vascular endothelial growth factor-C (VEGF-C), and its receptor VEGFR-3 (Flt-4) in primary gastric cancer and to explore the relevance among them and their correlation with clinicopathologic features of gastric cancer. MethodsThe VEGF-C, VEGFR-3, and CNTN-1 protein expressions of tumor tissues and normal gastric mucosa tissues in 68 patients with primary gastric cancer were analyzed by immunohistochemistry. The Flt-4-positive vessel density (FVD) and lymphatic vessel density (LVD) were also analyzed by VEGFR-3positive and D2-40-positive staining, respectively. ResultsThe positivity rate of VEGF-C, VEGFR-3, and CNTN-1 protein expression in the primary tumor was 57.4% (39/68), 60.3% (41/68), and 55.9% (38/68), respectively, which was significantly higher than that in the normal gastric mucosa tissues 〔20.6% (14/68), 23.5% (16/68), and 16.2% (11/68)〕， P=0.000. The expressions of VEGF-C, VEGFR-3, and CNTN-1 protein were significantly correlated with TNM stage, lymphatic vessel invasion, and lymph node metastasis (Plt;0.05). The expression of CNTN-1 protein was significantly correlated with VEGF-C (r=0.372, P=0.002) and VEGFR-3 protein expression (r=0.308, P=0.011). In tumor tissues of sixtyeight patients the FVD was (10.41±9.38)/HP, which was significantly lower than LVD 〔(18.19±7.44)/HP〕, P=0.000. Elevated FVD and LVD was significantly found in patients with tumor characterized by later TNM stage, severer lymphatic vessel invasion, and severer lymph node metastasis (Plt;0.05). The FVD of tumor was significantly correlated with VEGF-C (P=0.029) and CNTN-1 protein expression (P=0.003). The LVD of tumor was not significantly correlated with CNTN-1 (P=0.727), VEGF-C (P=0.173), and VEGFR-3 protein expression (P=0.924). The patients with positive expression of VEGF-C, VEGFR-3, and CNTN-1 protein showed poorer prognosis (Plt;0.05). ConclusionsElevated expression of CNTN-1 protein is observed in primary gastric cancer and correlated with VEGF-C and VEGFR-3 protein expression, indicating that combined detection has great value in prediction of invasive potential and prognosis. VEGF-C-mediated CNTN-1 overexpression may promote lymphatic invasion via lymphangiogenesis pathway in patients with gastric cancer.
ObjectivesTo investigate the ability of emergency medical rescue personnel in Sichuan province to collect information and contact resources at rescue sites, and to provide evidence for emergency training and drills. MethodsThe rescue site of a batch of critically ill patients in public emergency was simulated. The cross-sectional survey was made on rescue personnel at the city (prefecture) and county level of Sichuan province. The rating scale of on-site information contact ability was used to evaluate their performance. Because the score distribution does not conform to the normal distribution, the space between the median and interquartile was used to describe the score, and multiple measurement data was compared by the rank sum test. ResultsA total of 287 rescue drill personnel were included. The overall score M (P25, P75) of information contact ability was 19.57 (13.04, 28.26). The scores of each dimension were as follows: the safety zone was set as 0 (0, 10), the on-site hazard identification was 0 (0, 16.67), external contact and coordination was 50 (0, 50), internal coordination and command was 50 (16.67, 50), the on-site disaster statistics was 40 (10, 70), the on-site resource status was 0 (0, 0), and the on-site reinforcement demand was 0 (0, 0). Hierarchy by occupation: 19.57 (12.50, 28.26) for clinicians, 19.57 (14.13, 34.78) for nurses, 25 (14.67, 32.61) for medical skills, 21.74 (14.13, 30.44) for public health doctors, and 17.39 (9.78, 21.74) for health management. Hierarchy by titles: 21.74 (13.04, 28.26) for intermediate level, and 17.39 (10.33, 23.91) for advanced level. Scores of different dimensions, occupations and titles were compared respectively, and the differences were statistically significant (P<0.05). ConclusionsThe results of this survey show that the emergency medical rescue personnel at the city (prefecture) and county level of Sichuan province have insufficient overall ability to contact information on site, so those with insufficient ability need to be trained. The training focuses on the on-site resource status, on-site reinforcement demands, safety zone setting and the ability to identify on-site hazards.
In the Spring Festival of 2020, China waged an unexpected battle against coronavirus disease 2019. Within the scope of constructing smart hospitals, it has become a brand-new subject concerning how the construction can facilitate the scientific prevention and control of the epidemic. According to the development direction, basing on the concept of “patient-centered” medical services, and combining with the construction ideas of traditional medical information products and emerging technologies, Guangdong Provincial People’s Hospital, as the first government-leading “demonstration hospital for 5G application”, was fully dedicated to promoting the mode of contactless diagnosis and treatment and providing smart medical information service, thereby setting up a “scientific and technological firewall against the epidemic”.
Posterior-stabilized total knee prostheses have been widely used in orthopedic clinical treatment of knee osteoarthritis, but the patients and surgeons are still troubled by the complications, for example severe wear and fracture of the post, as well as prosthetic loosening. Understanding the in vivo biomechanics of knee prostheses will aid in the decrease of postoperative prosthetic revision and patient dissatisfaction. Therefore, six different designs of posterior-stabilized total knee prostheses were used to establish the musculoskeletal multibody dynamics models of total knee arthroplasty respectively, and the biomechanical differences of six posterior-stabilized total knee prostheses were investigated under three simulated physiological activities: walking, right turn and squatting. The results showed that the post contact forces of PFC Sigma and Scorpio NGR prostheses were larger during walking, turning right, and squatting, which may increase the risk of the fracture and wear as well as the early loosening. The post design of Gemini SL prosthesis was more conductive to the knee internal-external rotation and avoided the edge contact and wear. The lower conformity design in sagittal plane and the later post-cam engagement resulted in the larger anterior-posterior translation. This study provides a theoretical support for guiding surgeon selection, improving posterior-stabilized prosthetic design and reducing the prosthetic failure.
In the orthodontics process, intervention and sliding of an orthodontic bracket during the orthodontic process can arise large response of the labio-cheek soft tissue. Soft tissue damage and ulcers frequently happen at the early stage of orthodontic treatment. In the field of orthodontic medicine, qualitative analysis is always carried out through statistics of clinical cases, while quantitative explanation of bio-mechanical mechanism is lacking. For this purpose, finite element analysis of a three-dimensional labio-cheek-bracket-tooth model is conducted to quantify the bracket-induced mechanical response of the labio-cheek soft tissue, which involves complex coupling of contact nonlinearity, material nonlinearity and geometric nonlinearity. Firstly, based on the biological composition characteristics of labio-cheek, a second-order Ogden model is optimally selected to describe the adipose-like material of the labio-cheek soft tissue. Secondly, according to the characteristics of oral activity, a two-stage simulation model of bracket intervention and orthogonal sliding is established, and the key contact parameters are optimally set. Finally, the two-level analysis method of overall model and submodel is used to achieve efficient solution of high-precision strains in submodels based on the displacement boundary obtained from the overall model calculation. Calculation results with four typical tooth morphologies during orthodontic treatment show that: ① the maximum strain of soft tissue is distributed along the sharp edges of the bracket, consistent with the clinically observed profile of soft tissue deformation; ② the maximum strain of soft tissue is reduced as the teeth align, consistent with the clinical manifestation of common damage and ulcers at the beginning of orthodontic treatment and reduced patient discomfort at the end of treatment. The method in this paper can provide reference for relevant quantitative analysis studies in the field of orthodontic medical treatment at home and abroad, and further benefit to the product development analysis of new orthodontic devices.
The clinical performance and failure issues are significantly influenced by prosthetic malposition in unicompartmental knee arthroplasty (UKA). Uncertainty exists about the impact of the prosthetic joint line height in UKA on tibial insert wear. In this study, we combined the UKA musculoskeletal multibody dynamics model, finite element model and wear model to investigate the effects of seven joint line height cases of fixed UKA implant on postoperative insert contact mechanics, cumulative sliding distance, linear wear depth and volumetric wear. As the elevation of the joint line height in UKA, the medial contact force and the joint anterior-posterior translation during swing phase were increased, and further the maximum von Mises stress, contact stress, linear wear depth, cumulative sliding distance, and the volumetric wear also were increased. Furthermore, the wear area of the insert gradually shifted from the middle region to the rear. Compared to 0 mm joint line height, the maximum linear wear depth and volumetric wear were decreased by 7.9% and 6.8% at –2 mm joint line height, and by 23.7% and 20.6% at –6 mm joint line height, the maximum linear wear depth and volumetric wear increased by 10.7% and 5.9% at +2 mm joint line height, and by 24.1% and 35.7% at +6 mm joint line height, respectively. UKA prosthetic joint line installation errors can significantly affect the wear life of the polyethylene inserted articular surfaces. Therefore, it is conservatively recommended that clinicians limit intraoperative UKA joint line height errors to –2−+2 mm.