The Antioxidant Effect of Small Extracellular Vesicles Derived from Aloe vera Peels for Wound Healing

Background@#Extracellular vesicles (EVs) derived from plants have emerged as potential candidates for cosmetic and therapeutic applications. In this study, we isolated EVs from Aloe vera peels (A-EVs) and investigated the antioxidant and wound healing potential of A-EVs. @*Methods@#A-EVs were isolated by ultracentrifugation and tangential flow filtration and were characterized using transmission electron microscopy, nanoparticle tracking analysis. The cytotoxicity and cellular uptake of A-EVs were investigated by WST-1 assay and flow cytometry. The antioxidant effect of A-EVs was evaluated by superoxide dismutase (SOD) activity assay and cellular antioxidant activity (CAA) assay. The wound healing potential was assessed by in vitro scratch assay using human keratinocytes (HaCaT) and fibroblasts (HDF). The expression of nuclear factor erythroid 2–related factor 2 (Nrf2) and their associated genes was analyzed by quantitative RT-PCR. @*Results@#A-EVs displayed a round shape and had diameters from 50 to 200 nm. A-EVs showed good cytocompatibility on human skin cells and were internalized into HaCaT cells via clathrin-, caveolae-mediated endocytosis, and membrane fusion. The SOD activity and CAA assays exhibited that A-EVs had antioxidant activity and reduced intracellular ROS levels in H2O2-treated HaCaT cells in a dose-dependent manner. A scratch assay showed that A-EVs enhanced the migration ability of HaCaT and HDF. Moreover, A-EVs significantly upregulated the mRNA expression of Nrf2, HO-1, CAT, and SOD genes in H2O2-treated HaCaT cells. Our findings reveal that A-EVs could activate the antioxidant defense mechanisms and wound healing process via the Nrf2 activation. @*Conclusion@#Overall results suggest that the A-EVs are promising as a potential agent for skin regeneration.

The Antioxidant Effect of Small Extracellular Vesicles Derived from Aloe vera Peels for Wound Healing

Background@#Extracellular vesicles (EVs) derived from plants have emerged as potential candidates for cosmetic and therapeutic applications. In this study, we isolated EVs from Aloe vera peels (A-EVs) and investigated the antioxidant and wound healing potential of A-EVs. @*Methods@#A-EVs were isolated by ultracentrifugation and tangential flow filtration and were characterized using transmission electron microscopy, nanoparticle tracking analysis. The cytotoxicity and cellular uptake of A-EVs were investigated by WST-1 assay and flow cytometry. The antioxidant effect of A-EVs was evaluated by superoxide dismutase (SOD) activity assay and cellular antioxidant activity (CAA) assay. The wound healing potential was assessed by in vitro scratch assay using human keratinocytes (HaCaT) and fibroblasts (HDF). The expression of nuclear factor erythroid 2–related factor 2 (Nrf2) and their associated genes was analyzed by quantitative RT-PCR. @*Results@#A-EVs displayed a round shape and had diameters from 50 to 200 nm. A-EVs showed good cytocompatibility on human skin cells and were internalized into HaCaT cells via clathrin-, caveolae-mediated endocytosis, and membrane fusion. The SOD activity and CAA assays exhibited that A-EVs had antioxidant activity and reduced intracellular ROS levels in H2O2-treated HaCaT cells in a dose-dependent manner. A scratch assay showed that A-EVs enhanced the migration ability of HaCaT and HDF. Moreover, A-EVs significantly upregulated the mRNA expression of Nrf2, HO-1, CAT, and SOD genes in H2O2-treated HaCaT cells. Our findings reveal that A-EVs could activate the antioxidant defense mechanisms and wound healing process via the Nrf2 activation. @*Conclusion@#Overall results suggest that the A-EVs are promising as a potential agent for skin regeneration.

Metabolic Reprogramming by the Excessive AMPK Activation Exacerbates Antigen-Specific Memory CD8⁺ T Cell Differentiation after Acute Lymphocytic Choriomeningitis Virus Infection

During virus infection, T cells must be adapted to activation and lineage differentiation states via metabolic reprogramming. Whereas effector CD8⁺ T cells preferentially use glycolysis for their rapid proliferation, memory CD8⁺ T cells utilize oxidative phosphorylation for their homeostatic maintenance. Particularly, enhanced AMP-activated protein kinase (AMPK) activity promotes the memory T cell response through different pathways. However, the level of AMPK activation required for optimal memory T cell differentiation remains unclear. A new metformin derivative, IM156, formerly known as HL156A, has been reported to ameliorate various types of fibrosis and inhibit in vitro and in vivo tumors by inducing AMPK activation more potently than metformin. Here, we evaluated the in vivo effects of IM156 on antigen-specific CD8⁺ T cells during their effector and memory differentiation after acute lymphocytic choriomeningitis virus infection. Unexpectedly, our results showed that in vivo treatment of IM156 exacerbated the memory differentiation of virus-specific CD8⁺ T cells, resulting in an increase in short-lived effector cells but decrease in memory precursor effector cells. Thus, IM156 treatment impaired the function of virus-specific memory CD8⁺ T cells, indicating that excessive AMPK activation weakens memory T cell differentiation, thereby suppressing recall immune responses. This study suggests that metabolic reprogramming of antigen-specific CD8⁺ T cells by regulating the AMPK pathway should be carefully performed and managed to improve the efficacy of T cell vaccine.

The Modified Brostrom Procedure for Chronic Lateral Ankle Instability / 대한족부족관절학회지

PURPOSE: The purpose of this study is to evaluate the surgical results of modified Brostrom procedure for chronic lateral ankle instability and to assess whether or not associated injuries may affect postoperative satisfaction. MATERIALS AND METHODS: Twenty-four patients with chronic lateral ankle instability were evaluated retrospectively from August 1998 to March 2002. Average age was 29.3 years. All patients were performed pre & postoperative ankle anteroposterior and lateral view, stress anterior drawer and varus test using Telos device, MRI and intraoperative arthroscopic evaluations before ligament reconstruction. RESULTS: Of the 24 cases, 23 cases was improved more than average 12 points on AOFAS scales. On modified scales of Hamilton, 3 excellent, 20 good, 1 fair results. On stress view, average 2.2 mm difference was improved on anterior drawer test and average 1.7 degree on varus test. Associated injuries were 8 osteochondral defects, 4 anterior impingements, 2 loose bodies, 2 os subfibulare, 2 os submalleolare and 2 partial ruptures of peroneus brevis. 8 cases with no associated injuries rated excellent or good. CONCLUSION: The modified Brostrom procedure is believed to be an effective and successful method for chronic lateral ankle instability that didn't respond to conservative treatment. Because associated injuries in chronic lateral ankle instability may affect postoperative satisfaction, appropriate detection and treatment may need for postoperative satisfaction.

Radiologic Result of Displacement according to Position and Measurement Methods in Spondylolisthesis / 대한척추외과학회지

STUDY DESIGN: Prospective analysis was based on radiographic appearance in 80 cases of spondylolisthesis taken in positional change. PURPOSE: The aim of the study was to investigate the flexion-extension lateral radiographs about the difference between decubitus and upright position and the measurement method of displacement in spondylolisthesis. SUMMARY OF LITERATURE REVIEW: Although the flexion-extension lateral radiographs of spine were known the most preferable diagnostic method for spine instability, there are some debates about the difference of displacement according to the patient position and measurement methods. MATERIALS AND METHODS: The radiographs of 80 patients with spondylolisthesis were taken in the decubitus and upright position. Extent of the displacement were measured by Taillard, DuPuis, modified Qunnell & Stockdale method and Ferguson angle, slip angle, lordosis angle and vertebral centroid measurement of lumbar lordosis(CLL) were measured, according to position. RESULTS: Significant difference between the positions was shown on the CLL and lordosis angle. Differences between positions analyzed from Taillard, DuPuis, modified Qunnell & Stockdale method, Ferguson angle and slip angle had no statistical significance. Differences between positions analyzed from the pathologic movement of translation(>4 mm) had a clinically significance in the upright position rather than the decubitus. CONCLUSION: The lateral flexion-extension radiographs on upright position rather than decubitus position are considered as the more useful diagnostic method.

The Effect of Water Soluble Chitin on Wound Healing in Rats

The effect of water soluble chitin on wound healing in rats Chitin and chitosan, polysaccharides made up of polymeric N-acetyl glucosamine and D-glucosamine, are widely found in nature, forming skeletons of crustaceans and insects as well as components of bacteria cell walls. Chitin and chitosan have been known to have many useful biological properties such as biocompatibility, biodegradability, antimicrobial activity, and wound healing property. The key-point of practical use of chitin was making water soluble form. The purpose of this study was to compare the wound healing effect of water soluble with insoluble chitin. Full-thickness skin incision was made on the backs of the Sprague-Dawley rats. Three groups composed respectively with saline, water insoluble chitin and water soluble chitin were embedded in the wounds. The wound breaking strength and the collagen-hydroxyproline content of the wounded skins were measured and histological examination was performed at the time of 3, 7, 10 days respectively after the procedure. The tensile strength was maximum in case of water soluble chitin. The amount of collagen hydroxyproline was minimum in water soluble chitin. The wound treated with the water soluble and insoluble chitin was completely reepithelialized and granulation tissue in the wound was observed at 7 days after initial wounding. The arrangement of collagen fibers in the skin was orderly and similar to normal skin.

The Effect of Deacetylation of Chitin and Chitosan on Wound Healing in Rats

Chitin and chitosan, polysaccharides made up of polymeric N-acetly glucosamine and D-glucosamine, are widely found in nature, forming the skeletons of crustaceans and insects, as well as the components of bacteria cell walls. Chitin and chitosan have been known to have many useful biological properties such as biocompatibility, biodegradability, antimicrobial activity, and wound healing. There properties have been known to be different depending on the degree of deacetylation of chitin, but it has not yet been fully evaluated. The purpose of this study was to evaluate the wound healing effect by the degree of deacetylation. Full-thickness skin incision was made on the backs of Sprague-Dawley rats. Three concentrations of powder, comprising 90% chitin, 50% chitin and 10% chitin, were separately embedded in the wounds of 3 rat groups. The wound-breaking strength and the collagen-hydroxyproline content of the skin at the wound sites were measured and histological examination was performed at postoperative 3, 7, and 10 days. The 50% chitin group had the highest tensile strenght of all groups. But the 50% chitin and 90% chitin groups had the lowest collagen hydroxyproline levels among all groups. The wounds treated with 50% chitin powder were completely reepithelialized and granulation tissue in the wound was observed 7 days after initial wounding. The arrangement of collagen fibers in the skin was ordered and similar to normal skin The 50% chitin powder is considered to be the most efficient wound healing accelerator among different concentrations of chitin powder.

Selective Microscopic Decompression for Lumbar Spinal Stenosis with Osteoporosis: More than 3 Years Follow Up / 대한척추외과학회지

OBJECTS: There was a trend to perform fusion and instrumentation in spinal stenosis surgery, because of extensive decompression and instability. However, the introduction of microscope in spine operation can minimize the range of excision of anatomical structure and reduced the decompressin level in the multiple lesions and the incidence of spinal fusion. The purpose of this study were to assess the outcome of this procedure in 3 years follow up and to identify the clinical features of the patients and technical aspects of the operation that were associated with a poor outcome. MATERIALS AND METHODS: Twenty-one patients were identified as having had a microscopic decompression without arthrodesis, for degenerative lumbar spinal stenosis over 60 years or their who had osteoporosis with Saville's index 2 or higher. The follow up period was more than 3 years. The clinical results was evaluated by Kim's criteria. RESULTS: Eleven cases were above good results in two levels involved 14 cases, 2 cases above good results in three levels involved 5 cases and 1 case above good results in four levels involved 2 cases. In the cases of affected duration, 7 cases are less than 1 year or more than 5 years each 6 cases and 2 cases were above good results by the criteria. We concluded that the long-term outcome of decompressive surgery in the elderly is good; it does not differ from that reported for younger patients . CONCLUSIONS: Selective microscopic decompression is one of the effective method for the elderly patients or patients with osteoporosis in addition to multiple stenotic lesions.