Recyclable and biocompatible microgel-based supporting system for positive 3D freeform printing of silicone rubber

Tan Wen See,Shi Qian,Chen Shengyang,Bin Juhari Muhammad Aidil,Song Juha 대한의용생체공학회 2020 Biomedical Engineering Letters (BMEL) Vol.10 No.4

Additive manufacturing (AM) of biomaterials has evolved from a rapid prototyping tool into a viable approach for the manufacturing of patient-specific implants over the past decade. It can tailor to the unique physiological and anatomical criteria of the patient’s organs or bones through precise controlling of the structure during the 3D printing. Silicone elastomers, which is a major group of materials in many biomedical implants, have low viscosities and can be printed with a special AM platform, known as freeform 3D printing systems. The freeform 3D printing systems are composed of a supporting bath and a printing material. Current supporting matrices that are either commercially purchased or synthesized were usually disposed of after retrieval of the printed part. In this work, we proposed a new and improved supporting matrix comprises of synthesized calcium alginate microgels produced via encapsulation which can be recycled, reused, and recovered for multiple prints, hence minimizing wastage and cost of materials. The dehydration tolerance of the calcium alginate microgels was improved through physical means by the addition of glycerol and chemical means by developing new calcium alginate microgels encapsulated with glycerol. The recyclability of the heated calcium alginate microgels was also enhanced by a rehydration step with sodium chloride solution and a recovery step with calcium chloride solution via the ion exchange process. We envisaged that our reusable and recyclable biocompatible calcium alginate microgels can save material costs, time, and can be applied in various freeform 3D printing systems.

A Non-uniform Correction Algorithm Based on Scene Nonlinear Filtering Residual Estimation

Hongfei Song,Kehang Zhang,Wen Tan,Fei Guo,Xinren Zhang,Wenxiao Cao 한국광학회 2023 Current Optics and Photonics Vol.7 No.4

Due to the technological limitations of infrared thermography, infrared focal plane array (IFPA) imaging exhibits stripe non-uniformity, which is typically fixed pattern noise that changes over time and temperature on top of existing non-uniformities. This paper proposes a stripe non-uniformity correction algorithm based on scene-adaptive nonlinear filtering. The algorithm first uses a nonlinear filter to remove single-column non-uniformities and calculates the actual residual with respect to the original image. Then, the current residual is obtained by using the predicted residual from the previous frame and the actual residual. Finally, we adaptively calculate the gain and bias coefficients according to global motion parameters to reduce artifacts. Experimental results show that the proposed algorithm protects image edges to a certain extent, converges fast, has high quality, and effectively removes column stripes and non-uniform random noise compared to other adaptive correction algorithms.

Freeform 3D printing of soft matters: recent advances in technology for biomedical engineering

Chen Shengyang,Tan Wen See,Bin Juhari Muhammad Aidil,Shi Qian,Cheng Xue Shirley,Chan Wai Lee,Song Juha 대한의용생체공학회 2020 Biomedical Engineering Letters (BMEL) Vol.10 No.4

In the last decade, an emerging three-dimensional (3D) printing technique named freeform 3D printing has revolutionized the biomedical engineering field by allowing soft matters with or without cells to be printed and solidified with high precision regardless of their poor self-supportability. The key to this freeform 3D printing technology is the supporting matrices that hold the printed soft ink materials during omnidirectional writing and solidification. This approach not only overcomes structural design restrictions of conventional layer-by-layer printing but also helps to realize 3D printing of low-viscosity or slow-curing materials. This article focuses on the recent developments in freeform 3D printing of soft matters such as hydrogels, cells, and silicone elastomers, for biomedical engineering. Herein, we classify the reported freeform 3D printing systems into positive, negative, and functional based on the fabrication process, and discuss the rheological requirements of the supporting matrix in accordance with the rheological behavior of counterpart inks, aiming to guide development and evaluation of new freeform printing systems. We also provide a brief overview of various material systems used as supporting matrices for freeform 3D printing systems and explore the potential applications of freeform 3D printing systems in different areas of biomedical engineering.

Host range of Cybocephalus flavocapitis and Cybocephalus nipponicus, two potential biological control agents for the cycad aulacaspis scale, Aulacaspis yasumatsui

Sing-Ying Song,Ching-Wen Tan,Shaw-Yhi Hwang 한국응용곤충학회 2012 Journal of Asia-Pacific Entomology Vol.15 No.4

Host-range and host-specificity tests were performed with Cybocephalus flavocapitis T. R. Smith (Coleoptera:Cybocephalidae) and Cybocephalus nipponicus Endrödy-Younga (Coleoptera: Cybocephalidae), two biological control candidates against the invasive cycad aulacaspis scale, Aulacaspis yasumatsui Takagi (Hemiptera: Diaspididae). Seventeen native scale species plus the invasive A. yasumatsui scale were tested in growth chambers using nochoice tests and hosts suitable for each of the two predatory beetles. The results revealed that the two Cybocephalus beetles, one imported species from Thailand and one native species, both fed on relatively similar scale prey species. Additionally, the adult beetles of these two species oviposited only on Diaspididae scales. The results showed that both Cybocephalus beetles may share a similar host niche in Taiwan

The fourth new species of the leafhopper genus Thaioneura Song, Li & Dietrich from China (Hemiptera, Cicadellidae, Typhlocybinae)

Jiang Jia,Tan Wei-Wen,Song Yue-Hua 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.3

In this paper, one new species of the leafhopper genus Thaioneura Song, Li & Dietrich, 2016 from Guizhou Province, China are described and illustrated: Thaioneura huajiangensis sp. nov. And the female ovipositors are photographed and described. A key to distinguish all known species of the genus is provided. The hind wing venation of the new species are the same as the T. suphanburia and T. sinuata, and not common in the tribe Erythroneurini.

Effects of Low Temperature and Lactate on Osteogenic Differentiation of Human Amniotic Mesenchymal Stem Cells

Ting Chen,Yan Zhou,Wen-Song Tan 한국생물공학회 2009 Biotechnology and Bioprocess Engineering Vol.14 No.6

A functional relationship between the growth and the progression of events associated with osteogenic differentiation of human amniotic mesenchymal stem cells (hAMSCs) has been a fundamental question, which remains unclear. This study is aimed at investigating the effects of low temperature and lactate individually, and in combination on the growth and osteogenic differentiation of hAMSCs. It was shown that the growth of hAMSCs in growth medium was inhibited by both low-cultivation temperature and lactate. By extending culture period at low temperature, cell growth declined gradually, while the ALP expression and calcium deposition increased progressively. However, the growth of hAMSCs induced in osteogenic medium at 37oC was markedly enhanced by additional lactate. The ALP expression and calcium deposition, on the contrary, were significantly depressed. Furthermore, the synergistic actions of long-term low temperature and lactate resulted in more intense inhibition on both cell growth and osteogenic differentiation. Therefore, these findings may imply the co-contribution of the culture environment on the selective manipulation on the growth capacity and osteogenic differentiation potential of hAMSCs A functional relationship between the growth and the progression of events associated with osteogenic differentiation of human amniotic mesenchymal stem cells (hAMSCs) has been a fundamental question, which remains unclear. This study is aimed at investigating the effects of low temperature and lactate individually, and in combination on the growth and osteogenic differentiation of hAMSCs. It was shown that the growth of hAMSCs in growth medium was inhibited by both low-cultivation temperature and lactate. By extending culture period at low temperature, cell growth declined gradually, while the ALP expression and calcium deposition increased progressively. However, the growth of hAMSCs induced in osteogenic medium at 37oC was markedly enhanced by additional lactate. The ALP expression and calcium deposition, on the contrary, were significantly depressed. Furthermore, the synergistic actions of long-term low temperature and lactate resulted in more intense inhibition on both cell growth and osteogenic differentiation. Therefore, these findings may imply the co-contribution of the culture environment on the selective manipulation on the growth capacity and osteogenic differentiation potential of hAMSCs

Clonal Isolation and Characterization of Mesenchymal Stem Cells from Human Amnion

Min Wang,Yan Zhou,Wen-Song Tan 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.6

Mesenchymal stem cells (MSCs) derived from human amnion have both self-renewal capability and multipotency and are an attractive cell source for cell-based therapy. However, these cells have been shown to be heterogeneous, and as of yet no single-cell-derived MSCs clone has been established from human amnion. This study was carried out to isolate MSCs clones by limiting dilution method and compare their characteristics in vitro. Three clones (namely, 8B, 11D, and 11F) were established from a heterogeneous population of human amnion-derived cells (h-hAMCs). The clones and h-hAMCs successfully proliferated while demonstrating different cumulative population doublings (CPD) during an 80-day culture. In addition, the colony-forming efficiency (CFE) of h-hAMCs was significantly lower than those of 8B and 11F and higher than that of 11D. Clones 8B and 11F were tripotent,whereas 11D did not undergo chondrogenic differentiation. All cells expressed surface markers including CD29,CD44, and CD105 and notably, the clones expressed higher levels of CD105 than h-hAMCs (95.96, 97.05, 98.14% and 72.81% for 8B, 11D, 11F and h-hAMCs, respectively). In addition, the expression of stem cell gene Nanog-3 was associated with the differential differentiation potential of 11D from 8B, 11F, and h-hAMCs. These results suggested that significant differences existed between individual hAMCs. Further studies for developing novel methods to select sub-populations of hAMSCs are warranted for their clinical applications, in which CD105 and stem cell gene Nanog-3 are possible candidate markers.

The Association of Obstructive Sleep Apnea With Breast Cancer Incidence and Mortality: A Systematic Review and Meta-analysis

Dominic Wei Ting Yap,Nicole Kye Wen Tan,Benjamin Kye Jyn Tan,Yao Hao Teo,Veronique Kiak Mien Tan,Anna See,Song Tar Toh 한국유방암학회 2022 Journal of breast cancer Vol.25 No.3

Purpose: Emerging evidence from animal models suggests that intermittent hypoxia due to obstructive sleep apnea (OSA) is a risk factor for breast cancer. Despite their biological plausibility, human epidemiological studies have reported conflicting results. Therefore, we conducted a meta-analysis to delineate this relationship. Methods: We searched the PubMed, Embase, Scopus, and Cochrane Library databases for eligible studies from inception until June 6, 2021. Two reviewers selected randomized trials or observational studies reporting the association between OSA and breast cancer incidence compared with those without OSA. Two reviewers extracted relevant data and assessed the quality of evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework and Newcastle-Ottawa Scale (NOS). We pooled the maximally covariate-adjusted hazard ratios (HRs) using a random-effects inverse variance-weighted meta-analysis and performed pre-specified subgroup analyses. Results: We included six studies out of 1,707 records, comprising a combined cohort of 5,165,200 patients. All studies used the International Classification of Diseases codes to classify OSA and breast cancer. OSA patients had a 36% increased breast cancer risk (HR, 1.36; 95% confidence interval [CI], 1.03–1.80; N = 6, I2 = 96%) compared to those without OSA. Most studies adjusted for confounders, such as age, sex, obesity, diabetes mellitus, alcohol use, and hypertension. Subgroup analyses for studies with (1) multivariate adjustment and (2) at least five years of follow-up yielded HRs of 1.35 (95% CI, 0.98–1.87; N = 5, I2 = 96%) and 1.57 (95% CI, 1.14–2.18; N = 4; I2 = 90%), respectively. One Mendelian randomization study suggested a causal relationship, with a two-fold increase in the odds of breast cancer in patients with OSA. Conclusion: This meta-analysis suggested that OSA is a risk factor for breast cancer. Future studies should explore the dose-response relationship between OSA and breast cancer, and whether treatment may mitigate breast cancer risk or progression.

Effect of Oxygen and Shear Stress on Molecular Weight of Hyaluronic Acid Produced by Streptococcus zooepidemicus

( Xu Jie Duan ),( Yang Li ),( Xu Zhang ),( Wen Song Tan ) 한국미생물 · 생명공학회 2008 Journal of microbiology and biotechnology Vol.18 No.4

Mda-9/syntenin Promotes Human Brain Glioma Migration through Focal Adhesion Kinase (FAK)-JNK and FAK-AKT Signaling

Zhong, Dong,Ran, Jian-Hua,Tang, Wen-Yuan,Zhang, Xiao-Dong,Tan, Yun,Chen, Gui-Jie,Li, Xiao-Song,Yan, Yi Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.6

Invasion is usually recognized as the main reason for the high recurrence and death rates of glioma and restricts the efficacy of surgery and other therapies. Therefore, we aimed to investigate the mechanism involved in promotion effects of mda-9/syntenin on human glioma cell migration. The wound healing method was used to test the migration ability of human glioma cells CHG-5 and CHG-hS, stably overexpressing mda-9/syntenin. Western blotting was performed to determine the expression and phosphorylation of focal adhesion kinase (FAK) and JNK in CHG-5 and CHG-hS cells. The migration ability of CHG-hS cells was significantly higher than that of CHG-5 cells in fibronectin (FN)-coated culture plates. Phosphorylation of FAK on tyrosine 397, 576, and 925 sites was increased with time elapsed in CHG-hS cells. However, phosphorylated FAK on the tyrosine 861 site was not changed. Phosphorylated Src, JNK and Akt levels in CHG-hS cells were also significantly upregulated. Phosphorylation of JNK and Akt were abolished by the specific inhibitors SP600125 and LY294002, respectively, and the migration ability of CHG-hS cells was decreased, indicating that the JNK and PI3K/Akt pathways play important roles in regulating mda-9/syntenin-induced human brain glioma migration. Our results indicate Mda-9/syntenin overexpression could activate FAK-JNK and FAK-Akt signaling and then enhance the migration capacity of human brain glioma cells.