Method For Repair Of Defects Research Articles

Bone Marrow Mesenchymal Stem Cells-derived Exosomes Promote Survival of Random Flaps in Rats through Nrf2-mediated Antioxidative Stress.

Random flaps are the most used defect repair method for head and neck tumors and trauma plastic surgery. The distal part of the flap often undergoes oxidative stress (OS), ultimately leading to flap necrosis. Stem cells' exosomes exhibit potential effects related to anti-inflammatory, regenerative, and antioxidant properties. Nuclear factor erythroid-2-related factor 2 (Nrf2) is an important factor in regulating oxidative balance. Exosomes have been reported to monitor its transcription to alleviate OS. This study examined the impacts and underlying mechanisms of antioxidant actions of exosomes derived from bone marrow mesenchymal stem cells (BMSCs-Exo) on random flaps. BMSCs-Exo were injected into the tail veins of rats on days 0, 1, and 2 after surgery of random flaps. The rats were euthanized on day 3 to calculate the survival rate. Immunohistochemical staining, western blotting, dihydroethidium probe, superoxide dismutase, and malondialdehyde assay kits were used to detect the OS level. Human umbilical vein endothelial cells were cocultured with BMSCs-Exo and ML385 (an inhibitor of Nrf2) in vitro. BMSCs-Exo may significantly improve the survival rate of the random flaps by reducing apoptosis, inflammation, and OS while increasing angiogenesis. Besides, BMSCs-Exo can also increase mitochondrial membrane potential and reduce reactive oxygen species levels in vitro. These therapeutic effects might stem from the activation of the Kelch-like enyol-CoA hydratase (ECH)-associated protein 1 (Keap1)/Nrf2 signaling pathway. BMSCs-Exo improved the tissue antioxidant capacity by regulating the Keap1/Nrf2 signaling pathway. BMSCs-Exo may be a new strategy to solve the problem of random flap necrosis.

Limiting defect in vat photopolymerization via visual-guided in-situ repair

Vat photopolymerization 3D printing has gained significant attention due to its fast printing speed and high precision. However, the absence of effective quality assurance methods greatly limits its applications. Current vat photopolymerization cannot deal with commonly occurring defects during the printing process, such as random bubbles and resin underfill, making it challenging to consistently produce products that match designed geometry and functions. To address this, we propose an innovative vat photopolymerization solution via visual-guided in-situ repair to effectively eliminate printing defects. By utilizing an enhanced YOLOv5 network and K-means algorithm, real-time detection of bubbles and resin underfill can be achieved using image analysis. The optimal method for defect repair was then automatically generated via the adaptive scraper control and the repair slice edge smoothing generation algorithm, which was immediately received by hardware to adjust the ongoing printing parameters without interrupting the continuous printing process. Experimental results demonstrate that the aforementioned strategy can accurately differentiate typical defects such as bubbles and resin underfill, and precisely carry out in-situ defect repairs. Comparisons between repaired samples and defect-free samples show minimal differences in surface morphology and fracture strength (¡0.6%). The proposed solution is also applicable to various precursors. Clearly, the strategy above offers a universal approach to avoid defects in vat photopolymerization, which effectively enhances printing efficiency, reduces material wastage, and ensures the quality, accuracy, and reliability of printed products.

Limberg’s flap technique: a defect repair method for ear lobe reconstruction in recurrent earlobe keloids: a case report

The article acts to focus and aid in the localization of sound. Its shape is aesthetically important as it shows considerable inter-individual variability which reflects its multicomponent and is quite challenging for the surgeons during the planning of reconstruction as it is complex and equally important. It’s complex undulating structure and topography includes fibro elastic cartilage, perichondrium and the skin. The ear lobule is an important reference point for symmetry of the face and its loss causes an obvious aesthetic abnormality. Excessive healing can be as significant as delayed or non-healing. Recurrent earlobe keloids are among the most challenging conditions and may have significant psycho-social impact for the patient. Their aesthetic considerations are serious and despite a variety of treatment options, they often proved to be recurrent. It is likely that more operative interventions are required for excessive healing. Type II A defects are characterized by loss of the ear lobule without presence of a nubbin of tissue attached to the cheek. The goal of surgery should be an aesthetically pleasing reconstruction that maintains symmetry with the opposite ear lobule. The Limberg‑flap technique using a doubled‑over skin flap allows a one stage reconstruction of the ear lobule. The aesthetic results are generally well acceptable and hence here we present a case where we combine this technique with the excision for better results of long-term refractory cases.

The mechanical and repair behavior of damaged carbon/carbon composites

With the aim of understanding the effect of defect types on the mechanical performance of carbon/carbon (C/C) composites, three kinds of defects such as circle arc, square, and triangle shapes were prefabricated on their surfaces. The results show that the prefabricated defects damage the flexural strength of C/C composites compared to the pristine sample (101 ± 6 MPa). The flexural strength of C/C decreased by 30.84%, 45.84%, and 42.58% corresponding to the circle arc, square, and triangle type defects respectively. The defect-repair method with Ni-based solder as the additive was employed to repair the damaged C/C composites. After repair, the stress concentration of C/C composites decreases, and there is a good connection between carbon fiber and the repaired solder so that the load can be transferred continuously, therefore the flexural strength of C/C composites can be improved by 20–28%.

A method for defect repair of MFI-type zeolite membranes by multivalent ion infiltration

MFI-type zeolite membranes are effective for molecular separations, however suffer from non-selective defects. Here we show a means of plugging defects by infiltrating with rigidly bound multivalent ions, and demonstrate improvement to performance as salt rejecting (water selective) desalination membranes. Ion uptake into the MFI-type zeolite powder during exposure to a pH 2 solution containing Fe3+, Al3+, Ca2+ and Mg2+ showed a strong uptake of Fe3+ and Al3+. N2 gas porosimetry showed an increase in micropore proportion, being evidence that adsorbed ions did not enter the intrinsic pores of MFI-type zeolites, instead occupying the larger microporous (grain boundaries) and mesopores. X-ray diffraction (XRD) showed shrinkage in the zeolite crystal, being evidence of loss of monovalent cations within the intrinsic pores supported by the ion uptake results. Zeolite membranes were infiltrated with the solution at 7 MPa. Acid and water leaching revealed Fe3+ was the most strongly incorporated. This was confirmed by energy-dispersive X-ray spectroscopy (EDS) mapping on the surface of the membrane. The practical effect of the defect repair method was demonstrated on four membranes, where salt rejections in a reverse osmosis experiment were consistently improved (e.g. salt rejection increased from 24% to 84%). Further work should consider benefits to other applications of zeolite membranes including gas separation and pervaporation.

Distally based posterior interosseous adipofascial flap with delayed skin grafting for soft-tissue reconstruction of the dorsal hand

Objective To investigate the clinical results of reverse interosseous adipofascial flap with delayed skin grafting in the reconstruction of defects on the dorsal hand. Methods From March 2012 to May 2014, 16 patients with soft tissue defects on the dorsum of the hand were treated dorsal interosseous adipofascial flap in emergency setting. The size of the flaps ranged from 5 cm×4 cm to 10 cm×6 cm. The donor site at the forearm was closed directly. Seven days later, the fascial flap was covered with a full-thickness skin graft taken from the groin area. Vancouver Scar Scale was applied to assess the donor site scar. Five-point Likert scale was used to evaluate the appearance of the recipient site. Results One patient had partial loss of the flap involving 5% of the area at the distal end. All the other flaps survived completely. The skin grafts took well in all 16 patients. The duration of postoperative follow-up ranged from 6 to 12 months, with an average of 8 months. The texture and color of the skin graft were good, and the esthetic result was satisfactory. The mean score of Vancouver Scar Scale was 0.8. The mean score of Five-point Likert scale was 17. Conclusion The described adipofascial flap transfer with delayed skin graft is rather easy to perform without causing significant functional and aesthetic deficits to the donor site. It is a good method for repairing defects of the dorsal hand. Key words: Hand injuries; Treatment ontcome; Adipofascial flap; Posterior interosseous artery

Validation of an imageable surgical resection animal model of Glioblastoma (GBM).

Glioblastoma (GBM) is the most common and malignant primary brain tumour having a median survival of just 12-18 months following standard therapy protocols. Local recurrence, post-resection and adjuvant therapy occurs in most cases. U87MG-luc2-bearing GBM xenografts underwent 4.5mm craniectomy and tumour resection using microsurgical techniques. The cranial defect was repaired using a novel modified cranial window technique consisting of a circular microscope coverslip held in place with glue. Immediate post-operative bioluminescence imaging (BLI) revealed a gross total resection rate of 75%. At censor point 4 weeks post-resection, Kaplan-Meier survival analysis revealed 100% survival in the surgical group compared to 0% in the non-surgical cohort (p=0.01). No neurological defects or infections in the surgical group were observed. GBM recurrence was reliably imaged using facile non-invasive optical bioluminescence (BLI) imaging with recurrence observed at week 4. For the first time, we have used a novel cranial defect repair method to extend and improve intracranial surgical resection methods for application in translational GBM rodent disease models. Combining BLI and the cranial window technique described herein facilitates non-invasive serial imaging follow-up. Within the current context we have developed a robust methodology for establishing a clinically relevant imageable GBM surgical resection model that appropriately mimics GBM recurrence post resection in patients.

Free flaps in orbital exenteration: a safe and effective method for reconstruction

The aim of this study was to investigate the course of reconstructive treatment and outcomes with use of free flaps after orbital exenteration for malignancy. Charts of patients who had free flap reconstruction after orbital exenteration were retrospectively reviewed and the surgical technique was evaluated. Demographics, histology, surgical management, complications, locoregional control, and survival were analyzed. We performed 22 flaps in 21 patients. Reconstruction was undertaken mainly with anterolateral thigh (56 %), radial forearm (22 %), or parascapular (22 %) free flaps. Complications occurred in 33 % of patients and the flap's success rate was 91 %. The 5-year locoregional control and survival rates were 42 and 37 %, respectively. Free tissue transfer is a reliable, safe, and effective method for repair of defects of the orbit and periorbital structures resulting from oncologic resection. The anterolateral thigh flap is a versatile option to reconstruct the many orbital defects encountered.

Effective end-to-end repair of inferior alveolar nerve defect by using nerve sliding technique

The aim of this study was to introduce a new inferior alveolar nerve (IAN) defect repair method that does not require a nerve graft. The IAN was isolated after removal of a buccal cortical window. The scarred area or neuroma caused by the dental implant was excised with fresh cut ends and an epineural margin. If the excised gap was too wide for direct closure, the incisive nerve was intentionally transected 5 mm anterior to the mental foramen to obtain sufficient posterior mobilization of the distal stump of the IAN. The nerve ends were then approximated directly by sliding the distal nerve end to the proximal cut end. After completing the nerve repair by using four 10-0 nylon epineural sutures, the cortical window was repositioned with a microplate and screws. Using this technique, 3 nerve repairs without a nerve graft were successfully achieved for gaps ∼10 mm in size. The great advantage of this technique is that a moderate nerve defect can be anastomosed without a nerve graft when direct closure of the nerve segment is impossible without tension.

REPAIR OF DEFECTS IN SKULL BY READY MADE VITALLIUM PLATES

The various methods for repair of defects in the skull have not been entirely satisfactory. This subject has been reviewed by Grant and Norcross.1In 1936 Charles S. Venable and his associates2made an experimental study of the reaction set up in the tissues by various substances placed in the body. Various metals were studied together with a number of the so-called rustless and noncorrosive steels. Every substance that was studied (with one exception) produced changes in the tissues, necrosis of bone and other electrolytic effects. One alloy, called vitallium, made of cobalt, chromium and molybdenum, did not produce any reaction in the tissues. According to the authors, their experiments were repeated several times to check and recheck the apparent fact that this singular alloy seemed consistently to remain inert. These observations have proved to be of great practical value. Vitallium is now being used extensively in bone