The application of lightweight AI algorithms in postoperative rehabilitation of breast cancer.

The prevalence of breast cancer as a major global cancer has underscored the importance of postoperative recovery for breast cancer patients. Among the issues, postoperative patients are prone to spinal deformities, including scoliosis, which has drawn significant attention from healthcare professionals. The primary aim of this study is to design a postoperative recovery platform for breast cancer patients that can effectively detect posture changes, provide feedback and support to medical staff, assist doctors in formulating recovery plans, and prevent spinal deformities. The feasibility of the recovery platform is also validated through experiments. The development and validation of the experimental recovery platform. The recovery platform includes instrument design, patient data collection, model training and fine-tuning, and postoperative body posture evaluation by comparing preoperative and postoperative conditions. The evaluation results are provided to doctors to facilitate the formulation of personalized postoperative recovery plans. This paper comprehensively designs and implements the recovery platform and verifies its feasibility through simulation experiments. Statistical methods were employed for the validation of the rehabilitation platform in simulated experiments, with a significance level of p < 0.05. In comparison to static assessments like CT scans, this paper introduces a dynamic detection method that provides a more insightful analysis of body posture. The experiments also demonstrate the preventive capability of this method against post-operative spinal deformities, ultimately enhancing patients' self-image, restoring their confidence, and enabling them to lead more fulfilling lives.

Effect of expanded polytetrafluoroethylene thickness on paclitaxel release and edge stenosis in stent graft.

Stent grafts have been widely used to treat lower extremity arterial stenosis or occlusion. However, there are major issues with edge stenosis and loss of patency over time. Paclitaxel-coated stent grafts have been proven to be effective in preventing edge stenosis, but the insufficient amounts of paclitaxel released may limit the effectiveness of drug-eluting stent grafts. In this study, we examined whether paclitaxel-coated expanded polytetrafluoroethylene (ePTFE) stent graft thickness influences paclitaxel release properties and inhibits edge stenosis. Low-, medium-, and high-thickness paclitaxel-coated stent grafts were prepared by varying the thickness of inner and outer ePTFE layers. Surface morphologies of the stent grafts were analyzed using a scanning electron microscope. The stent grafts were then implanted in the iliac arteries of 20 healthy swine. Twelve pigs were used to assess edge stenosis, and digital subtraction angiography was performed at day 30 (n = 4), 90 (n = 4), and 180 (n = 4). Histological evaluation of the treated arteries was also performed. Eight pigs were used for pharmacokinetic analysis, and the treated arteries were obtained at day 1 (n = 2), 30 (n = 2), 90 (n = 2) and 180 (n = 2). Scanning electron microscopy confirmed that the mean pore size of the stent grafts decreased with increasing thickness. The results of angiographic and histological evaluation demonstrated that low-thickness ePTFE-stent grafts resulted in edge stenosis and apparent intimal hyperplasia at 180 days, whereas for medium-thickness ePTFE-stent grafts, no obvious edge stenosis and intimal hyperplasia was noted in the similar time period. The results of pharmacokinetic evaluation showed that at 180 days, the paclitaxel concentration of treated arteries of the medium group was 36 ± 53 ng/g, while concentrations in the low group was not detectable. Stent grafts with increased ePTFE thickness appear to allow for more delayed release of paclitaxel compared to low-thickness ePTFEs.

Mechanical and hydrodynamic effects of stent expansion in tapered coronary vessels.

Percutaneous coronary intervention (PCI) has become the primary treatment for patients with coronary heart disease because of its minimally invasive nature and high efficiency. Anatomical studies have shown that most coronary vessels gradually shrink, and the vessels gradually become thinner from the proximal to the distal end. In this paper, the effects of different stent expansion methods on the mechanical and hemodynamic behaviors of coronary vessels and stents were studied. To perform a structural-mechanical analysis of stent implantation, the coronary vessels with branching vessels and the coronary vessels with large bending curvature are selected. The two characteristic structures are implanted in equal diameter expansion mode and conical expansion mode, and the stress and mechanical behaviors of the coronary vessels and stents are analyzed. The results of the structural-mechanical analysis showed that the mechanical behaviors and fatigue performance of the cobalt-chromium alloy stent were good, and the different expansion modes of the stent had little effect on the fatigue performance of the stent. However, the equal diameter expansion mode increased distal coronary artery stress and the risk of vascular injury. The computational fluid dynamics analysis results showed that different stent expansion methods had varied effects on coronary vessel hemodynamics and that the wall shear stress distribution of conical stent expansion is more uniform compared with equal diameter expansion. Additionally, the vortex phenomenon is not apparent, the blood flow velocity is slightly increased, the hydrodynamic environment is more reasonable, and the risk of coronary artery injury is reduced.

Fluid-Structure Interaction Analysis on the Influence of the Aortic Valve Stent Leaflet Structure in Hemodynamics.

Transcatheter aortic valve replacement (TAVR) is a minimally invasive surgical treatment for heart valve disease. At present, personalized TAVR valves are not available for some patients. This study adopts the fluid-structure interaction (FSI) model of the research object that has a three-disc leaflet form and structural design in the valve leaflet area. The valve opening shape, orifice area, stress-strain, and distribution of hemodynamic flow and pressure were compared under the condition of equal contact area between valve and blood. The FSI method was used to simulate the complex three dimensional characteristics of the flow field more accurately around the valve after TAVR stent implantation. Three personalized stent systems were established to study the performance of the leaflet design based on computational fluid dynamics. By comparing the different leaflet geometries, the maximum stress on leaflets and stents of model B was relatively reduced, which effectively improved the reliability of the stent design. Such valve design also causes the opening area of the valve leaflet to increase and the low-velocity area of the flow field to decrease during the working process of the valve, thus reducing the possibility of thrombosis. These findings can underpin breakthroughs in product design, and provide important theoretical support and technical guidance for clinical research.

Investigation of mechanical behaviors and improved design of V-shaped braid stents.

V-shaped braid stents (VBSs), as highly retrievable and flexible nitinol stents, are extensively applied in endovascular diseases. They also cause less damage to vessel wall compared to tube-cutting stents. However, poor performance of VBS or suboptimal operation can give rise to unwanted clinical situations such as thrombosis and intimal hyperplasia. Therefore, research on designing factors affecting the performance of these devices is of great significance. Furthermore, simulation of stenting process can help designers understand the interactions of stents and vessel wall to reduce time to market. Thus, finite element analysis (FEA) and bench test are performed taking into account both designing factors and stenting process of VBS, including development of parametric modeling tool, research on the relationships among structural parameters and radial force, exploration of the interactions of VBS and vessel wall and pulsating load effect. This research was performed using a commercial solver Abaqus/standard with a user material subroutine (UMAT/nitinol). Structural parameters of VBS, unit-cell height and wire diameter have significant impacts on radial force, unit-cell number has slight influence on radial force, and arc diameter has almost negligible impact on radial force. Without pulsatile load, maximum stress and strain always occur in arc position; however, in pulsatile load, maximum stress and strain are gradually transformed to strut position. The stress created near vessel wall and VBS interface is higher than interaction stress due to pulsating load. The obtained result provided valuable information on the structural design of stents as well as the effects of stent on vessel wall and that vessel wall on stent deformation.Graphical abstract[Formula: see text].

A heparin-functionalized covered stent prepared by plasma technology.

In this study, the surface of the covered stent was treated by plasma technology to introduce amino functional groups, and glutaraldehyde and heparin were successfully grafted to prepare a heparin-functionalized covered stent (HPLCS). The preparation parameters such as plasma treatment power, plasma treatment time, concentration of glutaraldehyde and heparin, and pH of heparin solution were studied in detail. The functionalized heparin covered stent can make the titer of heparin reach 1.23 ± 0.03 IU/cm2. In animal experiments, after implantation in pigs for 6 months, the titer of heparin can still reach 0.93 ± 0.05 IU/cm2. This work provides a good method for preparing heparin covered stent.

Inhibition of edge stenosis of endografts in swine iliac arteries by a novel endograft with biodegradable coating at both ends.

OBJECTIVE: This study evaluated the effectiveness and safety of a novel endograft with a biodegradable coating at both ends in preventing edge stenosis in swine iliac arteries. The biodegradable coating was composed of polylactide and paclitaxel. METHODS: Four types of endograft were implanted in the iliac arteries of healthy swine: an endograft without coating (control group) and endografts with polylactide and paclitaxel coating containing 0.1, 0.3, or 3.6 µg/mm2 of paclitaxel. The edge stenosis of these endografts in swine iliac arteries was assessed using angiographic image data at 30, 90, and 180 days after the operation. After terminal angiography, histologic evaluation of the treated arteries was performed. The treated sections of iliac arteries and blood samples were obtained at 1, 7, 30, 90, and 180 days for pharmacokinetic analysis. RESULTS: The results of angiographic and histologic evaluation demonstrated that intimal hyperplasia contributed to edge stenosis and polylactide-paclitaxel coating effectively inhibited edge stenosis. At 30 days, edge stenosis was observed at both the proximal and distal edges of the endograft without coating. At 90 days, edge stenosis was detected for the endograft coated with 0.1 µg/mm2 paclitaxel, and ectasia dilation occurred at the proximal and distal edges of the endograft coated with 3.6 µg/mm2 paclitaxel. No edge stenosis or other adverse effects were observed at 90 and 180 days for the endograft coated with 0.3 µg/mm2 paclitaxel. In addition, for the endograft coated with 0.3 µg/mm2 paclitaxel, a pharmacokinetic analysis showed that the paclitaxel concentration of treated segments decreased from 14 264 ± 1020 ng/g at day 1 to 80 ± 70 ng/g at day 90, and 20 ± 40 ng/g at day 180. The plasma paclitaxel concentration was low at day 1 and no longer detected after 7 days. CONCLUSIONS: Polylactide and paclitaxel coating containing 0.3 µg/mm2 paclitaxel at both ends of endografts effectively and safely inhibits edge stenosis in swine iliac arteries.

Loading comparison of two structures in the moving tube of a non-invasive prosthesis.

BACKGROUND: The treatment of adolescent patients with distal femoral cancer has always been a concern. The limb-salvage, regarded as a mainstream treatment, had been developed in recent years, but its application in children still remains challenging. This is because it can lead to potential limb-length discrepancy from the continued normal growth of the contralateral lower body. The extendable prosthesis could solve this problem. The principle is that it can artificially control the length of the prosthesis, making it consistent with the length of the side of the lower limbs. However, this prosthesis has some complications. The extendable prosthesis is classified into invasive and minimally invasive, which extends the prosthesis with each operation. OBJECTIVE: We designed a new non-invasive prosthesis that can be extended in the body. Based on the non-invasive and extendable characteristics, we need to verify the supporting performance of this prosthesis. METHODS: We carried out a mechanical testing method and finite element analysis simulation. CONCLUSION: The support performance and non-invasively extension of this prosthesis were verified.

Design of equipment for preparing drug-eluting stents with single-sided coating.

BACKGROUND: Drug-eluting stent technology has rapidly developed in recent years. In particular, stents are used in percutaneous coronary intervention (PCI), which has become a vital method in clinic treatment. Although various methods are currently used to prepare drug-eluting stents, these methods are associated with respective limitations. OBJECTIVE: To design equipment for preparing drug-eluting stents with single-sided coating and to precisely accomplish the drug-coating process for a single side. METHODS: This coating equipment prepared stents in three stages: the precise displacement and translational motion and rotational motion of the operating platform; the recognition and positioning of the stent strut; and the utilisation of a pL-scale inkjet system. In order to control and synchronise the work of each subsystem, a central processing unit was installed. RESULTS: Through the analysis and solutions of various problems occurring in the experiment, the spraying equipment was improved, and its functions were perfected. Thus, the successful operation of the spraying equipment was realised. CONCLUSIONS: The design of the equipment introduced in this article meets the requirements for preparing drug-eluting stents.

Design and evaluation of a novel biodegradable inferior vena cava filter.

Inferior vena cava filter has been increasingly applied in clinical practice to prevent pulmonary embolism. Nowadays, various complications after implanting conventional filters seriously hinder clinical applications. Therefore, in this paper, a novel biodegradable inferior vena cava filter was designed based on biodegradable materials, which is an hourglass-like filter anchored inside a stent structure fixed by connecting fibers. Firstly, mechanical tests in crimp were performed to study the expansion properties of the filter, showing that the biodegradable inferior vena cava filter could achieve self-expansion easily. Furthermore, the biodegradable inferior vena cava filters and fibers were incubated in phosphate buffer media (pH = 7.4 ± 0.2) at 37°C for six months. Scanning electron microscope micrograph showed that the stents exhibited no significant dimensional and structural changes and had enough radial force to support the vessel. During the degradation period, the results of scanning electron microscope, gel permeation chromatography, differential scanning calorimetry and tensile strength analysis confirmed that the degradation rate of the hourglass-like filter was faster than the connecting fibers, achieving progressive degradation and thus avoiding the polymer fragments from blocking vessel. Cytotoxicity and hemolysis assay demonstrated good biocompatibility of the filter. For 5 mm × 10 mm sized thrombus, in vitro simulated thrombus capture test showed that the mean trapping efficiency of the filter was 90%, which was comparable to traditional inferior vena cava filter. In conclusion, all results exhibited that the as-designed biodegradable inferior vena cava filter has a potential in clinical application for patients who are at temporary high risk of venous thromboembolism.

Fabrication and characterization of a large medical balloon with ultra-high strength.

BACKGROUND: Transcatheter aortic valve implantation (TAVI) has emerged as a promising treatment strategy for patients with severe symptomatic aortic stenosis (AS). Moreover, characteristics of Chinese patients that are different from those of patients in Western countries, such as a high prevalence of bicuspid aortic valve (BAV), severe calcification, and a small peripheral artery diameter, have been observed. OBJECTIVE: A novel large medical balloon with ultra-high strength was fabricated through the blending modification of PA12/TR55. METHODS: The mechanical properties, particularly puncture resistance, of large balloons were thoroughly studied, and TR55, a modified nylon pellet with good mechanical properties and excellent compatibility with PA12, was applied to modify PA12. RESULTS: Compared with pure PA12, the fabricated PA12/TR55 balloon exhibited a higher bursting pressure, lower compliance, and higher punctures resistance while retaining good processability and excellent biocompatibility. The improved mechanical properties can be attributed to an increase in crystallinity and densification. CONCLUSIONS: The PA12/TR55 balloon is suitable for Chinese patients with bicuspid aortic valve and severe calcification and therefore has potential for clinical application in transcatheter aortic valve implantation. Moreover, this blending modification provides a simple but efficient method of solving other problems in cardiac angioplasty or cryoablation in which mechanical reinforcement of balloons may be necessary.

Improved synergetic therapy efficiency of cryoablation and nanoparticles for MCF-7 breast cancer.

AIM: Current cryoablation therapy easily induces a high tumor recurrence, it is therefore necessary to develop an effective method to enhance its antitumor efficacy. MATERIALS & METHODS: We solve the aforementioned problem by introducing doxorubicin (DOX) loading methoxy polyethylene glycol-polylactic-co-glycolic acid-poly-L-lysine-cyclic arginine-glycine-aspartic acid peptide nanoparticles (DOX nanoparticles) in the process of cryoablation. RESULTS: The combination of cryoablation and DOX nanoparticles greatly decreases the recurrence rate of breast cancer, which is owing to the specific targeting therapy of DOX nanoparticles for residuary breast cancer cells after cryoablation. Therefore, the survival time of MCF-7 breast cancer bearing mice significantly increases. CONCLUSION: The synergetic therapy of cryoablation and DOX nanoparticles is an effective therapy means for breast cancer. This strategy provides new means for treating breast cancer.

Application of controlled hypotension in cesarean section of pregnant women with high-risk hemorrhage.

To explore the application of controlled hypotension in cesarean section of pregnant women with high-risk hemorrhage. 75 cases were randomly divided into three groups: controlled hypotension Group 1 (Group H1), controlled hypotension Group 2 (Group H2) and normal blood pressure Group (Group N). The preoperative general data, intraoperative conditions, postpartum concurrent Symptoms and other indicators of all the cases in three groups were compared. The Apgar score, umbilical arterial blood gas and other indicators of the newborns were detected. There was no significant difference in the preoperative general data, Apgar score at 1 min and 5 min, the level of PH, PaO2, PaCO2 among the three groups (P>0.05). The intraoperative blood transfusion volume in group H1 and group H2 decreased significantly than that in group N (P<0.05), but there was no significant difference between group H1 and group H2 (P>0.05). Compared with group H1, the red cell transfusion volume in group H2 was significantly reduced (P<0.05). There was no significant difference in other intra-operative indexes such as bleeding volume, infusion volume, patient urine volume and hospitalization days among the three groups (P>0.05). Controlled hypotension (within 5 min of MAP down to 70% of basal blood pressure) can reduce the incidence of hemorrhage and postpartum hemorrhage during cesarean section in high-risk bleeding pregnant women and which had no bad effects on the incidence of complications and umbilical arterial blood gas indicators compared with control group.

Fe3O4 nanoparticles and cryoablation enhance ice crystal formation to improve the efficiency of killing breast cancer cells.

The key problem of cryoablation is that only freezing is often unable to kill the capillaries at tumor edges, leading to a high rate of recurrence. Here, we found that Fe3O4 nanoparticles were highly useful to improve the freezing capability of cryosurgery due to their ability to alter intracellular ice formation (IIF) and growth in tumor cells. The killing efficiency of cryoablation for MCF-7 breast cancer cells can be expected to be enhanced as the Fe3O4 nanoparticles concentration increased, it was mainly because that more IIF was induced by the participation of Fe3O4 nanoparticles during freezing, recrystallization and thawing. Furthermore, our results also showed that recrystallization contributed to the formation of extracellular embryonic crystals, which was capable of enhancing the efficiency of killing MCF-7 cells. This research is to develop an understanding of the mechanism of the cryoablation enhancing the killing efficiency in the presence of the Fe3O4 nanoparticles, and to promote their further application in tumor therapy.

Comparative Study of Degradation Behavior of Bioresorbable Cardiovascular Scaffolds.

This comparative study investigated the biodegradation behavior and mechanism of bioresorbable cardiovascular scaffolds using bench testing under physiological conditions and in vivo experiment. The results show that the molecular weight of the scaffold decreased with respect to time after implantation in both in vivo and in vitro tests. It was found that the molecular weights of the implanted scaffolds in the in vivo and in vitro models decreased to 61.8 and 68.5% respectively 6 months after implantation, but the thermodynamic properties of the scaffold material were not significantly affected by the 6-month degradation. Moreover, the study indicated that in spite of the 6-month degradation, the scaffold maintained sufficient radial strength and mechanical integrity. Furthermore, it was noted that the changes in the trends of the mechanical properties and degradation behavior of the scaffolds in the in vitro model were coherent with the results of the in vivo study, which means the in vitro study of the degradation behavior of polylactic acid (PLA) scaffold could offer clinical relevant data and physical insights to predict the in vivo performance.

Degradation model of bioabsorbable cardiovascular stents.

This study established a numerical model to investigate the degradation mechanism and behavior of bioabsorbable cardiovascular stents. In order to generate the constitutive degradation material model, the degradation characteristics were characterized with user-defined field variables. The radial strength bench test and analysis were used to verify the material model. In order to validate the numerical degradation model, in vitro bench test and in vivo implantation studies were conducted under physiological and normal conditions. The results showed that six months of degradation had not influenced the thermodynamic properties and mechanical integrity of the stent while the molecular weight of the stents implanted in the in vivo and in vitro models had decreased to 61.8% and 68.5% respectively after six month's implantation. It was also found that the degradation rate, critical locations and changes in diameter of the stents in the numerical model were in good consistency in both in vivo and in vitro studies. It implies that the numerical degradation model could provide useful physical insights and prediction of the stent degradation behavior and evaluate, to some extent, the in-vivo performance of the stent. This model could eventually be used for design and optimization of bioabsorbable stent.

[Investigations on registration for three-dimensional mapping of cardiac chambers and computed tomography segmented images].

In this paper, a novel registration method is presented for three-dimensional mapping of cardiac chambers and computed tomography (CT) segmented surfaces. The proposed method applies random perturbations to three-dimensional mapping of cardiac chambers in order to move out of local minima. It effectively solves the problem of the existing algorithm based on iterative closest point (ICP) in which the optimization often falls into local minima, and improves the registration accuracy and success rate. The registration experiment results show that the final registration accuracy and success rate of the proposed method are better than the existing ICP-based algorithm, and it can implement the registration when the three-dimensional mapping of cardiac chambers and CT segmented surface have a wide range of initial offset.

Cryopreservation of human embryonic stem cells: a protocol by programmed cooling.

Human embryonic stem (ES) cells have far-reaching applications in the areas of tissue engineering, regenerative medicine, pharmacology and basic scientific research. Although the culture conditions can maintain the human ES cells in an undifferentiated state for a transient period, spontaneous differentiation has also been observed during the routine culturing of ES cells. However, the maintenance of ES cells in the undifferentiated, pluripotent state for extended periods of time will be required in many areas of scientific research. Cryopreservation is a technology with potentially far reaching implication for the development and widespread use of such cell lines. This study was undertaken to develop and optimize a protocol for cryopreservation of human ES cells through programmed cooling. The effects of the seeding temperature, the cooling rate and the sub-zero temperature to which the samples were cooled before plunging into liquid nitrogen(the terminal temperature), all significantly affected the recovery of cryopreserved ES cells. After studying these factors, an improved protocol was obtained: the sample was cooled from 0 degree C to -35 degree C at a cooling rate of 0.5 degree per min, with seeding was set at -10 degree C, before being plunged immediately into the liquid nitrogen. Using this protocol, 9 of 11 colony fragments survived freezing and thawing and could be cultured for prolonged periods. They retained the properties of pluripotent cells, had a normal karyotype and showed histochemical staining for alkaline phosphatase.