Bio-medical materials and engineering最新文献

Background: Transjugular intrahepatic portosystemic shunt (TIPS), which artificially creates a portocaval shunt to reduce portal venous pressure, has gradually become the primary treatment for portal hypertension (PH). However, there is no prefect shunting scheme in TIPS to balance the occurrence of postoperative complications and effective haemostasis.

Objective: To construct cirrhotic PH models and compare different shunting schemes in TIPS.

Methods: Three cases of cirrhotic PH with different liver volumes were selected for enhanced computed tomography scanning. The models for different shunting schemes were created using Mimics software, and following FLUENT calculation, all the models were imported into the software computational fluid dynamic-post for processing. In each shunting scheme, the differences in portal vein pressure, hepatic blood perfusion and blood flow from the superior mesenteric vein in the shunt tract were compared. The coefficient G was adapted to evaluate the advantages and disadvantages.

Results: (1) Concerning the precise location of the shunt tract, the wider the diameter of the shunt tract, the lower the pressure of the portal vein and the lesser the hepatic blood perfusion. Meanwhile, the pressure drop objective was not achieved with the 6 mm-diameter shunting scheme. (2) The 8 mm-diameter shunting scheme through the left portal vein (LPV) had the highest coefficient G.

Conclusion: The 8 mm-diameter shunting scheme through the LPV may demonstrate a superior effect and prognosis in TIPS procedures.

Background: Polysaccharide hydrogel is one of the most important materials for the colon target drug release system. However, the degradation time of polysaccharide hydrogel is much longer than the retention time in the colon. The drugs are expelled from the body before being released.

Objective: In order to match the degradation of drug carriers and their retention time in the colon, a rapidly degradable konjac glucomannan (KGM) hydrogel was designed for colon target drug release.

Methods: A crosslinker containing azo bond, olsalazine, was used to prepare the rapidly degradable KGM hydrogel. The degradation and drug release of the hydrogels with different crosslinking densities in the normal buffer and the human fecal medium were studied to evaluate the efficiency of colon drug release.

Results: More than 50% of the KGM hydrogel by weight was degraded and more than 60% of the 5-fluorouracil (5-Fu) was released within 48 h in 5% w/v human fecal medium.

Conclusion: The drug was released more rapidly in a simulated colon environment than in a normal buffer. Furthermore, the drug release was controlled by the degradation of the hydrogel. The KGM hydrogel containing azo crosslinker has great potential for colon drug release.

Background: Numerous studies have confirmed that stimulating the mid-brain motor nuclei can regulate movement forcibly for robo-pigeons, but research on behavior modulation using non-motor nuclei is scarce.

Objective: In this study, we constructed a spatial preference behavior by stimulating the stratum griseum periventriculare (SGP), a nucleus correlated with fear and escape, for robo-pigeons.

Methods: The study was carried out in a square-enclosed experimental field, with a designated box serving as the 'safe' area for the robo-pigeons. If the robo-pigeon exits this area, the SGP will be stimulated. After a brief training period, the robo-pigeons will have a clear spatial preference for the box.

Results: The result from five pigeons has shown that, after simple training, the animals develop a spatial preference for the box. They can quickly return to the box in any situation when the SGP is stimulated, with a success rate exceeding 80% (89.0 ± 6.5%). Moreover, this behavior is highly stable and remains consistent, unaffected by changes in the location of the box or the interference box.

Conclusion: The results prove that using the electrical stimulus could enable animals to accomplish more complex tasks. It may offer a novel approach to regulating pigeon behavior and further advance the study of cyborg animals.

Background: Polymeric electrospun mats have been used as scaffolds in tissue engineering for the development of novel materials due to its characteristics. The usage of synthetic materials has gone in decline due to environmental problems associated with their synthesis and waste disposal. Biomaterials such as biopolymers have been used recently due to good compatibility on biological applications and sustainability.

Objective: The purpose of this work is to obtain novel materials based on synthetic and natural polymers for applications on tissue engineering.

Methods: Aloe vera mucilage was obtained, chemically characterized, and used as an active compound contained in electrospun mats. Polymeric scaffolds were obtained in single, coaxial and tri-layer structures, characterized and evaluated in cell culture.

Results: Mucilage loaded electrospun fibers showed good compatibility due to formation of hydrogen bonds between polymers and biomolecules from its structure, evidenced by FTIR spectra and thermal properties. Cell viability test showed that most of the obtained mats result on viability higher than 75%, resulting in nontoxic materials, ready to be used on scaffolding applications.

Conclusion: Mucilage containing fibers resulted on materials with potential use on scaffolding applications due to their mechanical performance and cell viability results.

Background: Inspired by natural bones, many organic components were added to Calcium Phosphate Cements (CPCs) to improve their mechanical strength. However, the strength of these composite CPCs is limited by the low strength of organic components itself and the weak interaction between organic components and CPCs.

Objective: Firstly, a composite CPC containing mussel-inspired adhesive, Poly-(Dopamine Methacrylamide-co-2-methoxy Ethylacrylate) (pDM) was developed. Secondly, the interactions between pDM and CPC and their effect on mechanical properties were investigated.

Methods: The interactions between pDM and CPC were performed by Nuclear Magnetic Resonance, Laser Raman, X-ray Photoelectron Spectroscopy, Fourier Transform-Infrared Spectroscopy and X-ray Diffraction Analysis.

Results: The toughness and compressive strength of pDM-CPC scaffold were both significantly enhanced, because of the enhanced interface binding strength among CPC and pDM due to their interaction and the improved mechanical strength of pDM owing to its self-oxidation cross-linking. The toughness of pDM-CPC scaffolds increased with the increased contents of pDM, while pDM-CPC scaffold containing 35 wt.% pDM had the highest compressive strength of all, which the latter was more than five times compared to that of CPC.

Conclusion: The mechanically strong pDM-CPC scaffolds has potential application in bone regeneration as well as in craniofacial and orthopedic repair.

Background: Systemic-to-pulmonary shunt is a palliative procedure used to decrease pulmonary blood flow in congenital heart diseases. Shunt stenosis or occlusion has been reported to be associated with mortality; therefore, the management of thrombotic complications remains a challenge for most congenital cardiovascular surgeons. Despite its importance, the optimal method for shunt anastomosis remains unclear.

Objective: The study investigates the clinical benefits of the punch-out technique over conventional methods in the anastomosis process of Systemic-to-pulmonary shunt, focusing on its potential to reduce shunt-related complications.

Methods: Anastomotic models were created by two different surgeons employing both traditional slit and innovative punch-out techniques. Computational tomography was performed to construct three-dimensional models for computational fluid dynamics (CFD) analysis. We assessed the flow pattern, helicity, magnitude of wall shear stress, and its gradient.

Results: The anastomotic flow area was larger in the model using the punch-out technique than in the slit model. In CFD simulation, we found that using the punch-out technique decreases the likelihood of establishing a high wall shear stress distribution around the anastomosis line in the model.

Conclusion: The punch-out technique emerges as a promising method in SPS anastomosis, offering a reproducible and less skill-dependent alternative that potentially diminishes the risk of shunt occlusion, thereby enhancing patient outcomes.

Background: Zinc oxide eugenol (ZOE) cement is a popular dental material due mainly to its analgesic, antibacterial and anti-inflammatory effects. The formulation of ZOE cement from nano particle-sized zinc oxide (ZnO) has the potential to increase these properties as well as reduce its adverse effects to the surrounding tissues.

Objective: This study evaluated the subcutaneous tissue response towards nano ZOE cements (ZOE-A and ZOE-B) in comparison to conventional ZOE (ZOE-K).

Methods: Test materials were implanted into 15 New Zealand white rabbits. Tissue samples were obtained after 7, 14, and 30 days (n = 5 per period) for histopathological evaluation of inflammatory cell infiltrate, fibrous tissue condensation, and abscess formation.

Results: ZOE-A showed the lowest score for the variable macrophage and lymphocyte at day 7. Both ZOE-A and ZOE-B presented lower fibrous tissue condensation and abscess formation compared to conventional ZOE-K. By day 30, ZOE-A exhibited less lymphocytic and neutrophilic infiltrate compared to the other materials, while ZOE-B had the lowest score for macrophages. ZOE-K exerted higher inflammatory cell response at almost all of the experimental periods. All of the materials resulted in thin fiber condensation after 30 days.

Conclusions: Rabbit tissue implanted with ZOE-A and ZOE-B showed better response compared to ZOE-K.

Background: The postoperative varus/valgus stability assessment in stress X-rays has been established as an evaluation index. However, it is performed by the two-dimensional (2D) method rather than the three-dimensional (3D) method.

Objective: This study aimed to identify the precision and reproducibility of measuring varus/valgus stress X-rays three-dimensionally and to examine varus/valgus stability under anesthesia in imageless robotic assisted total knee arthroplasty (rTKA).

Methods: This prospective study analyzed 52 consecutive rTKAs (five males, 67 ± 5.3 years; 47 females, 74 ± 5.9 years). Postoperative varus/valgus stress X-rays in knee extension under anesthesia at manual maximum stress were three-dimensionally assessed by 2D-3D image matching technique using the 3D bone and component models. Varus/valgus angle between components (VV angle) in no stress, valgus stress, varus stress, medial joint opening (MJO), and lateral joint opening (LJO) were evaluated, clarifying this method's precision and reproducibility and valgus/varus stability.

Results: All parameters' precision and reproducibility had <1° mean differences and high intra- and inter-class correlation coefficients. Bland-Altman plots showed no fixed and proportional bias. Non-stress VV angle, valgus VV angle, varus VV angle, MJO, and LJO were 3.6 ± 1.2°, 1.0 ± 1.4°, 7.1 ± 1.9°, 1.5 ± 1.0 mm, and 2.8 ± 2.7 mm, respectively.

Conclusion: This prospective study demonstrated that (1) the three-dimensional measurement method provided sufficient precision and reproducibility, and (2) the rTKAs could achieve good postoperative varus/valgus stability with a small standard deviation.