Potential of methacrylated acemannan for exerting antioxidant-, cell proliferation-, and cell migration-inducing activities in vitro.

BACKGROUND: Acemannan is an acetylated polysaccharide of Aloe vera extract with antimicrobial, antitumor, antiviral, and antioxidant activities. This study aims to optimize the synthesis of acemannan from methacrylate powder using a simple method and characterize it for potential use as a wound-healing agent. METHODS: Acemannan was purified from methacrylated acemannan and characterized using high-performance liquid chromatography (HPLC), Fourier-transform infrared spectroscopy (FTIR), and 1H-nuclear magnetic resonance (NMR). 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays were performed to investigate the antioxidant activity of acemannan and its effects on cell proliferation and oxidative stress damage, respectively. Further, a migration assay was conducted to determine the wound healing properties of acemannan. RESULTS: We successfully optimized the synthesis of acemannan from methacrylate powder using a simple method. Our results demonstrated that methacrylated acemannan was identified as a polysaccharide with an acetylation degree similar to that in A. vera, with the FTIR revealing peaks at 1739.94 cm-1 (C = O stretching vibration), 1370 cm-1 (deformation of the H-C-OH bonds), and 1370 cm-1 (C-O-C asymmetric stretching vibration); 1H NMR showed an acetylation degree of 1.202. The DPPH results showed the highest antioxidant activity of acemannan with a 45% radical clearance rate, compared to malvidin, CoQ10, and water. Moreover, 2000 µg/mL acemannan showed the most optimal concentration for inducing cell proliferation, while 5 µg/mL acemannan induced the highest cell migration after 3 h. In addition, MTT assay findings showed that after 24 h, acemannan treatment successfully recovered cell damage due to H2O2 pre-treatment. CONCLUSION: Our study provides a suitable technique for effective acemannan production and presents acemannan as a potential agent for use in accelerating wound healing through its antioxidant properties, as well as cell proliferation- and migration-inducing activities.

Bioinspired Sandcastle Worm-Derived Peptide-Based Hybrid Hydrogel for Promoting the Formation of Liver Spheroids.

The generation of hepatic spheroids is beneficial for a variety of potential applications, including drug development, disease modeling, transplantation, and regenerative medicine. Natural hydrogels are obtained from tissues and have been widely used to promote the growth, differentiation, and retention of specific functionalities of hepatocytes. However, relying on natural hydrogels for the generation of hepatic spheroids, which have batch to batch variations, may in turn limit the previously mentioned potential applications. For this reason, we researched a way to establish a three-dimensional (3D) culture system that more closely mimics the interaction between hepatocytes and their surrounding microenvironments, thereby potentially offering a more promising and suitable system for drug development, disease modeling, transplantation, and regenerative medicine. Here, we developed self-assembling and bioactive hybrid hydrogels to support the generation and growth of hepatic spheroids. Our hybrid hydrogels (PC4/Cultrex) inspired by the sandcastle worm, an Arg-Gly-Asp (RGD) cell adhesion sequence, and bioactive molecules derived from Cultrex BME (Basement Membrane Extract). By performing optimizations to the design, the PC4/Cultrex hybrid hydrogels can enhance HepG2 cells to form spheroids and express their molecular signatures (e.g., Cyp3A4, Cyp7a1, A1at, Afp, Ck7, Ck1, and E-cad). Our study demonstrated that this hybrid hydrogel system offers potential advantages for hepatocytes in proliferating, differentiating, and self-organizing to form hepatic spheroids in a more controllable and reproducible manner. In addition, it is a versatile and cost-effective method for 3D tissue cultures in mass quantities. Importantly, we demonstrate that it is feasible to adapt a bioinspired approach to design biomaterials for 3D culture systems, which accelerates the design of novel peptide structures and broadens our research choices on peptide-based hydrogels.

Interleukin-6 transiently promotes proliferation of osteoclast precursors and stimulates the production of inflammatory mediators.

BACKGROUND: Clinical data and phenotypes of several in vivo models demonstrated that interleukin-6 (IL-6) is an essential positive regulator in inflammation-induced bone loss. However, how IL-6 affect bone resorption and the osteoclast differentiation remains in debate. In this study we elucidate the cellular responses of receptor activator of nuclear factor kappa-Β ligand (RANKL)-stimulated RAW254.7 macrophage, the process mimicking osteoclast differentiation, upon IL-6 co-stimulation. IL-6 is a pleiotropic cytokine triggering various cellular responses, ranging from pro-inflammatory responses, differentiation to proliferation or apoptosis in different cell types. Those cellular events in the RANKL-stimulated RAW cells were examined to understand how differentiating monocytic cells respond to IL-6 exposure. MATERIALS AND METHODS: Proliferation, apoptosis, differentiation and Pro-inflammatory responses of RANKL-stimulated RAW254.7 macrophage treated with or without IL-6 were measured by MTT assay, quantitative PCR assay of the expression of apoptotic genes, osteoclast differentiation markers, and pro-inflammatory genes, respectively. The results were collected from different time points in a 6-day differentiation period. Also, western blot on STAT3, ERK and AKT were also performed to investigate the IL-6 signaling in those cells. CONCLUSIONS: IL-6 triggered transient proliferation, but not apoptosis, in RANKL-stimulated RAW cells. Osteoclastogenesis was disrupted as the expression of essential genes for bone resorption were inhibited, and the osteoclast precursors maintained their undifferentiated phenotypes, with pro-inflammatory genes upregulated. Our results suggested that IL-6 interferes osteoclastogenesis. Additionally, IL-6 promote pro-inflammatory responses of monocytic cells and aggravate inflammation.

Different susceptibilities of osteoclasts and osteoblasts to glucocorticoid-induced oxidative stress and mitochondrial alterations.

Glucocorticoid-induced bone loss is the most common form of secondary osteoporosis. This toxic effect has not been efficiently managed, possibly due to the incomplete understanding of the extraordinarily diverse cellular responses induced by glucocorticoid treatment. Previous literatures revealed that high dose of exogenous glucocorticoid triggers apoptosis in osteocytes and osteoblasts. This cell death is associated with glucocorticoid-induced oxidative stress. In this study, we aimed to investigate the mechanisms of glucocorticoid-induced apoptosis in osteoblasts and examine the responses of osteoclasts to the synthetic glucocorticoid, dexamethasone. We demonstrated the biphasic effects of exogenous glucocorticoid on osteoblastic mitochondrial functions and elevated intracellular oxidative stress in a dose- and time-dependent manner. On comparison, similar treatment did not induce mitochondrial dysfunctions and oxidative stress in osteoclasts. The production of reactive oxygen/nitrogen species was decreased in osteoclasts. The differences are not due to varying efficiency of cellular antioxidant system. The opposite effects on nitrogen oxide synthase might provide an explanation, as the expression levels of nos2 gene are suppressed in the osteoclast but elevated in the osteoblast. We further revealed that glucocorticoids have a substantial impact on the osteoblastic mitochondria. Basal respiration rate and ATP production were increased upon 24 h incubation of glucocorticoids. The increase in proton leak and nonmitochondrial respiration suggests a potential source of glucocorticoid-induced oxidative stress. Long-term incubation of glucocorticoids accumulates these detrimental changes and results in cytochrome C release and mitochondrial breakdown, consequently leading to apoptosis in osteoblasts. The mitochondrial alterations might be other sources of glucocorticoid-induced oxidative stress in osteoblasts.

16 Gb/s PAM4 UWOC system based on 488-nm LD with light injection and optoelectronic feedback techniques.

A 16 Gb/s four-level pulse amplitude modulation (PAM4) underwater wireless optical communication (UWOC) system based on 488-nm laser diode (LD) with light injection and optoelectronic feedback techniques is proposed and successfully demonstrated. Experimental results show that such a 1.8-GHz 488-nm blue light LD with light injection and optoelectronic feedback techniques is enough forceful for a 16 Gb/s PAM4 signal underwater link. To the authors' knowledge, this study is the first to successfully adopt a 488-nm LD transmitter with light injection and optoelectronic feedback techniques in a PAM4 UWOC system. By adopting a 488-nm LD transmitter with light injection and optoelectronic feedback techniques, good bit error rate performance (offline processed by Matlab) and clear eye diagrams (measured in real-time) are achieved over a 10-m underwater link. The proposed system has the potential to play a vital role in the future UWOC infrastructure by effectively providing high transmission rate (16 Gb/s) and long underwater transmission distance (10 m).

Bidirectional fiber-IVLLC and fiber-wireless convergence system with two orthogonally polarized optical sidebands.

A bidirectional fiber-invisible laser light communication (IVLLC) and fiber-wireless convergence system with two orthogonally polarized optical sidebands for hybrid cable television (CATV)/millimeter-wave (MMW)/baseband (BB) signal transmission is proposed and experimentally demonstrated. Two optical sidebands generated by a 60-GHz MMW signal are orthogonally polarized and separated into different polarizations. These orthogonally polarized optical sidebands are delivered over a 40-km single-mode fiber (SMF) transport to effectually reduce the fiber dispersion induced by a 40-km SMF transmission and the distortion caused by the parallel polarized optical sidebands. To the best of our knowledge, this work is the first to adopt two orthogonally polarized optical sidebands in a bidirectional fiber-IVLLC and fiber-wireless convergence system to reduce fiber dispersion and distortion effectually. Good carrier-to-noise ratio, composite second order, composite triple beat, and bit error rate (BER) are achieved for downlink transmission at a 40-km SMF operation and a 100-m free-space optical (FSO) link/3-m RF wireless transmission. For up-link transmission, good BER performance is acquired over a 40-km SMF transport and a 100-m FSO link. The approach presented in this work signifies the advancements in the convergence of SMF-based backbone and optical/RF wireless-based feeder.

64 Gb/s PAM4 VCSEL-based FSO link.

A 64 Gb/s four-level pulse amplitude modulation (PAM4) vertical-cavity surface-emitting laser (VCSEL)-based free-space optical (FSO) link with an external light injection scheme is proposed and successfully demonstrated. Experimental results show that the 11.2 GHz VCSEL with an external light injection scheme is sufficiently powerful for 64 Gb/s PAM4 FSO links. This study is the first one that adopts a 1550-nm VCSEL transmitter with an external light injection scheme in a 64 Gb/s PAM4 FSO link. The link performances of the proposed PAM4 VCSEL-based FSO links have been analyzed in real-time in terms of eye diagrams and offline processed by Matlab in terms of bit error rate (BER) performances. Good BER performance and clear eye diagrams are acquired over a 100-m free-space link. Such a proposed 64 Gb/s PAM4 VCSEL-based FSO link with an external light injection scheme is a promising one for providing high transmission rate and long transmission distance.

45 Gb/s PAM4 transmission based on VCSEL with light injection and optoelectronic feedback techniques.

A 45 Gb/s four-level pulse amplitude modulation (PAM4) transmission based on an 850 nm/7.4 GHz vertical cavity surface emitting laser (VCSEL) with light injection and optoelectronic feedback techniques is proposed. Experimental results show that such an 850 nm/7.4 GHz VCSEL with light injection and optoelectronic feedback techniques is powerful enough for a 45 Gb/s PAM4 signal transmission. To the best of our knowledge, this Letter is the first to adopt a VCSEL transmitter with light injection and optoelectronic feedback techniques in a 45 Gb/s PAM4 transmission system. Good bit error rate performance and three independent clear eye diagrams are achieved over a 200-m OM4 multimode fiber transport. This proposed 45 Gb/s PAM4 VCSEL-based transmission system has great potential for providing effective bandwidth in short-reach optical data communications.

Bidirectional fiber-wireless and fiber-IVLLC integrated system based on polarization-orthogonal modulation scheme.

A bidirectional fiber-wireless and fiber-invisible laser light communication (IVLLC) integrated system that employs polarization-orthogonal modulation scheme for hybrid cable television (CATV)/microwave (MW)/millimeter-wave (MMW)/baseband (BB) signal transmission is proposed and demonstrated. To our knowledge, it is the first one that adopts a polarization-orthogonal modulation scheme in a bidirectional fiber-wireless and fiber-IVLLC integrated system with hybrid CATV/MW/MMW/BB signal. For downlink transmission, carrier-to-noise ratio (CNR), composite second-order (CSO), composite triple-beat (CTB), and bit error rate (BER) perform well over 40-km single-mode fiber (SMF) and 10-m RF/50-m optical wireless transport scenarios. For uplink transmission, good BER performance is obtained over 40-km SMF and 50-m optical wireless transport scenario. Such a bidirectional fiber-wireless and fiber-IVLLC integrated system for hybrid CATV/MW/MMW/BB signal transmission will be an attractive alternative for providing broadband integrated services, including CATV, Internet, and telecommunication services. It is shown to be a prominent one to present the advancements for the convergence of fiber backbone and RF/optical wireless feeder.

Optimization of culture conditions for stem cells derived from human anterior cruciate ligament and bone marrow.

Tissue engineering with stem cells is a fascinating approach for treating anterior cruciate ligament (ACL) injuries. In our previous study, stem cells isolated from the human anterior cruciate ligament were shown to possess extensive proliferation and differentiation capabilities when treated with specific growth factors. However, optimal culture conditions and the usefulness of fetal bovine serum (FBS) as a growth factor in in vitro culture systems are yet to be determined. In this study, we compared the effects of different culture media containing combinations of various concentrations of FBS and the growth factors basic fibroblastic growth factor (bFGF) and transforming growth factor-ß1 (TGF-ß1) on the proliferation and differentiation of ligament-derived stem cells (LSCs) and bone marrow mesenchymal stem cells (BMSCs). We found that α-MEM plus 10% FBS and bFGF was able to maintain both LSCs and BMSCs in a relatively undifferentiated state but with lower major extracellular matrix (ECM) component gene expression and protein production, which is beneficial for stem cell expansion. However, the differentiation and proliferation potentials of LSCs and BMSCs were increased when cultured in MesenPRO, a commercially available stem cell medium containing 2% FBS. MesenPRO in conjunction with TGF-ß1 had the greatest ability to induce the differentiation of BMSCs and LSCs to ligament fibroblasts, which was evidenced by the highest ligamentous ECM gene expression and protein production. These results indicate that culture media and growth factors play a very important role in the success of tissue engineering. With α-MEM plus 10% FBS and bFGF, rapid proliferation of stem cells can be achieved. In this study, MesenPRO was able to promote differentiation of both LSCs and BMSCs to ligament fibroblasts. Differentiation was further increased by TGF-ß1. With increasing understanding of the effects of different culture media and growth factors, manipulation of stem cells in the desired direction for ligament tissue engineering can be achieved.

Comparison of potentials between stem cells isolated from human anterior cruciate ligament and bone marrow for ligament tissue engineering.

We have previously isolated and identified stem cells from human anterior cruciate ligament (ACL). The purpose of this study was to evaluate the differences in proliferation, differentiation, and extracellular matrix (ECM) formation abilities between bone marrow stem cells (BMSCs) and ACL-derived stem cells (LSCs) from the same donors when cultured with different growth factors, including basic fibroblast growth factor (bFGF), epidermal growth factor, and transforming growth factor-beta 1 (TGF-beta1). Ligament tissues and bone marrow aspirate were obtained from patients undergoing total knee arthroplasty and ACL reconstruction surgeries. Proliferation, colony formation, and population doubling capacity as well as multilineage differentiation potentials of LSCs and BMSCs were compared. Gene expression and ECM production for ligament engineering were also evaluated. It was found that BMSCs possessed better osteogenic differentiation potential than LSCs, while similar adipogenic and chondrogenic differentiation abilities were observed. Proliferation rates of both LSCs and BMSCs were enhanced by bFGF and TGF-beta1. TGF-beta1 treatment significantly increased the expression of type I collagen, type III collagen, fibronectin, and alpha-smooth muscle actin in LSCs, but TGF-beta1 only upregulated type I collagen and tenascin-c in BMSCs. Protein quantification further confirmed the results of differential gene expression and suggested that LSCs and BMSCs increase ECM production upon TGF-beta1 treatment. In summary, in comparison with BMSCs, LSCs proliferate faster and maintain an undifferentiated state with bFGF treatment, whereas under TGF-beta1 treatment, LSCs upregulate major tendinous gene expression and produce a robust amount of ligament ECM protein, making LSCs a potential cell source in future applications of ACL tissue engineering.

Modulation of proliferation and differentiation of human anterior cruciate ligament-derived stem cells by different growth factors.

We have previously isolated and identified stem cells from human cruciate ligaments. The goal of this study was to evaluate the proliferation and differentiation abilities of ligament-derived stem cells (LSCs) cultured with growth factors, including fibroblast growth factor 2 (FGF-2), epidermal growth factor, and transforming growth factor-beta 1 (TGF-b1). The ligament tissues were obtained from patients with anterior cruciate ligament injuries receiving arthroscopic surgeries. LSCs were obtained by collagenase digestion and plating as previously reported. Surface immunophenotype and the potential for trilineage differentiation into osteoblasts, chondrocytes, and adipocytes were confirmed. It was found that proliferation of the cells was enhanced with the addition of FGF-2 and TGF-b1. Upon TGF-b1 treatment, expression of collagen type I and type III, tenascin-c, fibronectin, and a-smooth muscle actin were significantly upregulated. Additionally, LSCs treated with TGF-b1 and FGF-2 increased the production of collagenous and noncollagenous extracellular matrix protein. Together, these results demonstrate that LSCs respond differently to various cytokines, and the results further validate the potential of using cruciate ligament tissue as a stem cell source for tissue engineering purposes.

Experience in the use of the long Gamma nail for 16 femoral shaft fracture that have occurred following initial Asian Pacific Gamma nail fixation for pertrochanteric fractures.

From January 1993 to September 2002, 931 patients suffered from intertrochanteric fracture and subrochanteric fracture received open reduction and internal fixation with APGN in our institute. Among these patients, 16 patients (1.7%) developed a femoral shaft fracture after the initial fixation with APGN. Removal of the APGN, closed reduction and fixation with long Gamma nail (LGN) was performed in all the 16 patients. The patients were followed for 12-60 months (average, 39.8 months). The union time of fracture was 12-24 weeks (average, 18.5 weeks) for femoral shaft fractures and 12-20 weeks (average, 16 weeks) for peritrochanteric fractures. Two early complications were noted, including one superficial (6%) infection and one deep (6%) infection. Two malunions (12.5%) developed with no definite functional impairment. The functional results using the Harris hip score were good to excellent. In conclusion, closed reduction and internal fixation with a LGN is very effective in the management of a femoral shaft fracture, a complication of a previous APGN that had been initially used for stabilisation of a pertrochanteric fracture.

Efficacy of dilute betadine solution irrigation in the prevention of postoperative infection of spinal surgery.

STUDY DESIGN: Prospective, single-blinded, randomized study. OBJECTIVES: To evaluate the efficacy of dilute betadine irrigation of spinal surgical wounds in prevention of postoperative wound infection. SUMMARY AND BACKGROUND: Deep wound infection is a serious complication of spinal surgery that can jeopardize patient outcomes and increase costs. Povidoneiodine is a widely used antiseptic with bactericidal activity against a wide spectrum of pathogens, including methicillin-resistant Staphylococcus aureus. The aim of this study was to evaluate the efficacy of dilute betadine solution in the prevention of wound infection after spinal surgery. METHODS: Four hundred and fourteen patients undergoing spinal surgery were randomly assigned to two groups. In group 1 (208 patients), surgical wounds were irrigated with dilute betadine solution (3.5% betadine) before wound closure. Betadine irrigation was not used in group 2 (206 patients). Otherwise, perioperative management was the same for both groups. RESULTS: Mean length of follow-up was 15.5 months in both groups (range, 6-24 months). No wound infection occurred in group 1. One superficial infection (0.5%) and six deep infections (2.9%) occurred in group 2. The differences between the deep infection rate (P = 0.0146) and total infection rate (P = 0.0072) were significant between the two groups. CONCLUSIONS: Our report is the first prospective, single-blinded, randomized study to evaluate the clinical effectiveness of dilute betadine solution irrigation for prevention of wound infection following spinal surgery. We recommended this simple and inexpensive measure following spinal surgery, particularly in patients with accidental wound contamination, risk factors for wound infection, or undergoing surgery in the absence of routine ultraviolet light, laminar flow, and isolation suits.

Treatment of complex subtrochanteric fracture with the long gamma AP locking nail: a prospective evaluation of 64 cases.

BACKGROUND: Complex subtrochanteric fractures are uncommon injuries and challenging to manage. We elucidate the role of the Long Gamma AP Locking Nail (LGAPN) in the management of such fractures in the acute stage. METHODS: Between 1992 and 2002, 64 consecutive cases with nonpathologic complex subtrochanteric fractures managed with the LGAPN were enrolled in this study. Associated injuries were present in 16 cases. The average follow-up period was 68 months. RESULTS: Mean time to union was 14 weeks. There were two complications (one wound infection and one delayed union). The time to union and functional results were not statistically different between different ages (below 50 years old, or older than 50 years) and the number of distal locking screws used (one or two). Longer time to union is noted in patients with a longer operation time and a more comminuted fracture pattern by the AO classification. CONCLUSION: Closed reduction and internal fixation with the LGAPN were proven to be safe and effective in the treatment of complex traumatic subtrochanteric fractures in all age groups, and one distal locking screw is sufficient for distal fixation.

Periacetabular giant cell tumor treated with intralesional excision and allograft reconstruction.

Giant cell tumors of the acetabulum are uncommon lesions. Their diagnosis is often delayed due to their slow progression, late onset symptoms and easily been obscured by bowel gas in plain pelvic radiographs. The tumor size is always very large at the time of diagnosis, with major nerve and joint involvement. Management of such tumor remains challenging to orthopedic surgeons. Between 1992 and 1999, 3 acetabular giant cell tumors were diagnosed and managed at our institution. The treatment modality was intralesional tumor excision with structural allograft reconstruction. The margin of tumor was routinely managed with high-speed burring and phenol application. All 3 patients were free of local recurrence at a mean follow-up of 89 months. Postoperative palsy of sciatic nerve occurred in 1 patient, but no complications such as wound infection or fracture were seen. The nerve palsy recovered completely 1 year later. The final functional outcome of the 3 patients was excellent. The result appears that intralesional excision with adjuvant therapy is feasible in the management of giant cell tumor of the acetabulum and is able to obtain a satisfactory outcome.