Publications by authors named "Dongqing Li"

206 Publications

A surface charge governed nanofluidic diode based on a single polydimethylsiloxane (PDMS) nanochannel.

Authors:
Jun Li Dongqing Li

J Colloid Interface Sci 2021 Aug 24;596:54-63. Epub 2021 Mar 24.

Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. Electronic address:

Hypothesis: Nanofluidic diodes have attracted intense attention recently. Commonly used materials to design these devices are membrane-based short nanopores and aligned Carbon nanotube bundles. It is highly desirable and very challenging to develop a nanofluidic diode based on a single PDMS nanochannel which is easier to be introduced into an integrated electronic system on a chip. Layer-by-layer (LBL) deposition of charged polyelectrolytes can change the size and surface properties of PDMS nanochannels that provides new possibilities to develop high-performance nanofluidic based on PDMS nanochannels.

Experiments: A novel design of nanofluidic diode is presented by controlling the surface charges and sizes of single PDMS nanochannels by surface modification using polyelectrolytes. Polybrene (PB) and Dextran sulfate (DS) are used to reduce the PDMS nanochannel size to meet the requirement of ion gating by LBL method and generate opposite surface charges at the ends of nanochannels. The parameters of such a nanofluidic diode are investigated systematically.

Findings: This nanofluidic diode developed in this work has high effective current rectification performance. The rectification ratio can be as high as 218 which is the best ever reported in PB/DS modified nanochannels. This rectification ratio reduces with high voltage frequency and ionic concentration whereas increases in shorter nanochannels.
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http://dx.doi.org/10.1016/j.jcis.2021.03.126DOI Listing
August 2021

Hypofractionated Low-Dose Radiotherapy Combined with Immune Checkpoint Inhibition in Metastatic Solid Tumors.

Onco Targets Ther 2021 4;14:773-783. Epub 2021 Feb 4.

Cancer Center, The Affiliated Changzhou No. 2 People's Hospital of Nanjing Medical University, Changzhou, 213001, People's Republic of China.

Background: The combination of radiotherapy and immunotherapy can bring benefits to patients, especially advanced patients. However, conventional radiotherapy brings about great adverse reactions. How about the hypofractionated low-dose radiotherapy?

Materials And Methods: In this retrospective cohort study, we included 32 patients with metastatic solid tumors treated with hypofractionated radiotherapy combined with an immune checkpoint inhibitor. Patients underwent radiotherapy of 4Gy/Fx on day 1, 3, and 5, and received single-drug immunotherapy of PD-1 inhibitor on day 2. We evaluated the following outcomes: objective response rate (ORR), disease control rate (DCR), change of nonirradiated and irradiated lesions, quality of life, and symptom improvement.

Results: Among the 32 patients, the ORR was 9.4% (3/32) and the DCR was 56.25% (18/32). Hypofractionated radiotherapy combined with immunotherapy showed a remarkable efficacy of local control on metastatic tumor patients. Local masses irradiated in two patients (6.25%) were complete remission, partial response rate was 37.5% (12 patients), and 56.25% was stability (18 patients). Out of those 18 patients, 15 patients had the local masses shrank more or less. The ORR of local control reached 43.75%, and its DCR was 100%. In addition, the intratumor necrosis rate was 44.4% in the SD patients. Median progression-free survival was 3.8 months (95%Cl: 2.2-5.4). By treating the local mass, the symptoms of most patients were alleviated, and the quality of life was improved.

Conclusion: Our retrospective analysis revealed that hypofractionated radiotherapy combined with immunotherapy was effective in local control, it also relieved clinical symptoms and improved quality of life. The adverse effect rate was low. However, the incidence of abscopal effects was low either. This mode was suitable for the palliative treatment and expected to improve survival for patients with metastatic tumors.
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http://dx.doi.org/10.2147/OTT.S289937DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7869699PMC
February 2021

Prognostic Value of a Clinical Biochemistry-Based Nomogram for Coronavirus Disease 2019.

Front Med (Lausanne) 2020 18;7:597791. Epub 2021 Jan 18.

Department of Respiratory and Critical Care Medicine, Jinyintan Hospital, Wuhan, China.

This study aimed to explore the predictive value of a clinical biochemistry-based nomogram in COVID-19. The plasma or serum concentrations/levels of carcinoembryonic antigen (CEA) and other biomarkers, e.g., C-reactive protein (CRP), white blood cell (WBC), interleukin-6 (IL-6), ferritin (Fer), procalcitonin (PCT), lymphocyte percentage (L%), D-dimer (D2), and neutrophils percentage (Neu%), were assessed in 314 hospitalized patients with confirmed COVID-19. The area under the curve was used to estimate the diagnostic and prognostic value for COVID-19. Cox and logistic regression analyses were used to estimate the independent prognostic risk factors for the survival of patients with COVID-19. Receiver operating characteristic (ROC) curves were used to determine the area under the curve (AUC) values for CEA, IL-6, CRP, PCT, Fer, D-dimer levels and L%, Neu%, and WBC to assess disease classification. The critical values for these markers to predict severe disease type were then determined. The hazard ratio of prognosis for risk of COVID-19 identified CEA, WBC, CRP, PCT, Fer, D-dimer, Neu%, and L% as independent prognostic factors. For the nomogram of overall survival (OS), the C-index was 0.84, demonstrating a good discriminative performance. An OS nomogram for the clinical diagnosis and treatment of COVID-19 was constructed using biomarkers. These data will be useful for the diagnosis, management, and therapy of COVID-19.
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http://dx.doi.org/10.3389/fmed.2020.597791DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7848223PMC
January 2021

Electrokinetic detection and separation of living algae in a microfluidic chip: implication for ship's ballast water analysis.

Environ Sci Pollut Res Int 2021 May 11;28(18):22853-22863. Epub 2021 Jan 11.

Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.

Detecting living algae from treated ship's ballast water is an important task for port state control (PSC) under the requirement of the International Ballast Water Convention. In this paper, electrokinetic detection and separation of living algae from NaClO- and UV-treated ship's ballast water in a microfluidic chip are presented. The electrokinetic movement of algae in a straight poly ethylene glycol (PEG)-modified PDMS microchannel filled with 10% PEG solution was measured by using an optical microscope. The experimental results show that the moving velocity of dead algae is lower by more than 80% in comparison with living algae. The decreased velocity is larger for larger dead algae and the velocity is decreased to zero for dead algae larger than 6 μm in diameter. A curve was obtained to evaluate the vitality of algae with similar moving velocity but different sizes. Electrokinetic separation of living algae from a mixture sample in a straight channel was also achieved. The method presented in this paper provides a moving velocity-based approach for quickly evaluating the living status of algae in treated ship's ballast water.
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http://dx.doi.org/10.1007/s11356-020-12315-5DOI Listing
May 2021

The effect of Q-switched 1064-nm dymium-doped yttrium aluminum garnet laser on the skin barrier and collagen synthesis through miR-24-3p.

Lasers Med Sci 2021 Jan 5. Epub 2021 Jan 5.

Department of Dermatology, The First Affiliated Hospital of Kunming Medical University, No. 295, Xichang Road, Kunming, 650032, Yunnan Province, People's Republic of China.

Due to the increase of the world's population aging, how to restore youthfulness to the skin has attracted much attention. It is well known that collagen synthesis and changes in skin barrier play an important role in the process of skin aging. However, whether Q-switched 1064-nm Nd:YAG laser (1064-QSNYL) determines the involvement of miRNAs in skin collagen synthesis and skin barrier changes remains to be elucidated. Upstream miRNAs of p38 molecular pathway have been predicted by bioinformatic database and the relationship between miRNAs and p38 verified by dual-luciferase reporter gene and Western blotting. RT-qPCR analysis detected the expression of miR-24-3p and mRNA for collagen and skin barrier-related molecules, such as keratin 10 (K10), filaggrin, and Aquaporin 4 (APQ4), in mice back skin and in the keratinocyte cell line HaCaT. Western blotting and immunofluorescence (IF) have been used to detect collagen expression and to localize, as well as quantify K10, filaggrin, and APQ4, respectively. In this study, we show that p38 is the main target gene of miRNA-24-3p, and laser irradiation at 1.5 J/cm inhibits miR-24-3p expression. Irradiation treatment upregulates the moisture, elasticity, hydroxyproline, and superoxide dismutase content of mice skin, as well as inhibits trans-epidermal water loss. Irradiation also increases collagen, K10, filaggrin, and APQ4 in both mice skin and HaCaT cells. Interestingly, we found that miR-24-3p overexpression inhibits the effect of irradiation on collagen synthesis and skin barrier. We show for the first time that 1064-QSNYL promotes collagen synthesis and protective effects on skin barrier by downregulating miR-24-3p.
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http://dx.doi.org/10.1007/s10103-020-03214-9DOI Listing
January 2021

Histone Demethylase Promotes Cervical Cancer Malignancy Through the /KIF14/Hedgehog Axis.

Onco Targets Ther 2020 19;13:11957-11973. Epub 2020 Nov 19.

Department of Gynecological Oncology Radiotherapy, Jilin Cancer Hospital, Changchun 130012, Jilin, People's Republic of China.

Background: Lysine demethylase 3A () has been increasingly recognized as an important epigenetic regulator involved in cancer development. This study aims to explore the relevance of to cervical cancer (CC) progression and the molecules involved.

Materials And Methods: Tumor and the adjacent tissues from CC patients were collected. expression in tissues and CC cell lines and its correlation with the survival and prognosis of patients were determined. Malignant potentials of CC cells and the angiogenesis ability of HUVECs were measured to evaluate the function of on CC progression. The interactions among , H3K9me2 and , and the binding between and were validated through ChIP and luciferase assays. Altered expression of and was introduced to explore their roles in CC development.

Results: was abundantly expressed in CC tissues and cells and linked to dismal prognosis of CC patients. Knockdown of suppressed malignant behaviors of CC cells. was found to increase expression through the demethylation of H3K9me2. Overexpression of blocked the inhibiting roles of sh-KDM3A. could bind to the promoter region of to trigger its transcription. Overexpression ofaggravated the malignant behaviors of CC cells and the angiogenesis ability of HUVECs, and it activated the Hedgehog signaling pathway. Artificial activation of Hedgehog by Sag1.5 diminished the effects of sh-KDM3A. These changes were reproduced in vivo.

Conclusion: This study evidenced that promotes -mediated transcription to promote CC progression with the involvement of the Hedgehog activation.
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http://dx.doi.org/10.2147/OTT.S276559DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7682655PMC
November 2020

The Immune Functions of Keratinocytes in Skin Wound Healing.

Int J Mol Sci 2020 Nov 20;21(22). Epub 2020 Nov 20.

Center for Molecular Medicine, Ming Wai Lau Centre for Reparative Medicine, Department of Medicine Solna, Dermatology and Venereology Division, Karolinska Institute, 17176 Stockholm, Sweden.

As the most dominant cell type in the skin, keratinocytes play critical roles in wound repair not only as structural cells but also exerting important immune functions. This review focuses on the communications between keratinocytes and immune cells in wound healing, which are mediated by various cytokines, chemokines, and extracellular vesicles. Keratinocytes can also directly interact with T cells via antigen presentation. Moreover, keratinocytes produce antimicrobial peptides that can directly kill the invading pathogens and contribute to wound repair in many aspects. We also reviewed the epigenetic mechanisms known to regulate keratinocyte immune functions, including histone modifications, non-protein-coding RNAs (e.g., microRNAs, and long noncoding RNAs), and chromatin dynamics. Lastly, we summarized the current evidence on the dysregulated immune functions of keratinocytes in chronic nonhealing wounds. Based on their crucial immune functions in skin wound healing, we propose that keratinocytes significantly contribute to the pathogenesis of chronic wound inflammation. We hope this review will trigger an interest in investigating the immune roles of keratinocytes in chronic wound pathology, which may open up new avenues for developing innovative wound treatments.
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http://dx.doi.org/10.3390/ijms21228790DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7699912PMC
November 2020

Safety and Efficacy of Low-Dosage Apatinib Monotherapy in Advanced Lung Squamous-Cell Carcinoma: A Prospective Cohort Study.

Onco Targets Ther 2020 10;13:11529-11535. Epub 2020 Nov 10.

Cancer Center, The Affiliated Changzhou No. 2 People's Hospital of Nanjing Medical University, Changzhou 213000, People's Republic of China.

Background: Lung squamous-cell carcinoma (SqCC) is the second most common histology in non-small-cell lung carcinomas (NSCLCs). The treatment options for advanced lung SqCC are still an unmet medical need. Apatinib, a small-molecule inhibitor of vascular endothelial growth factor receptor-2 (VEGFR-2), is beneficial in the therapy of advanced NSCLC patients. This study aimed to preliminarily assess the efficacy and safety of low-dosage apatinib in patients with advanced lung SqCC.

Methods: In this single-arm, open-label, investigator-initiated phase II prospective study (ChiCTR1800019808), we enrolled patients aged 54-80 years with platinum-refractory or chemotherapy rejected advanced lung squamous-cell carcinoma. Key exclusion criteria included major blood vessel involvement and gross hemoptysis with an amount of more than 20 mL. Apatinib at an initial dose of 250 mg was administered to patients once daily until disease progression, unacceptable toxicity, withdrawal, or death. The primary endpoint was progression-free survival (PFS) in all patients. We assessed the adverse events according to the treatment received.

Results: Thirty-eight patients were enrolled between June 11, 2015 and August 29, 2018. Two patients failed to evaluate treatment efficacy for personal reasons, and thus 36 patients were eligible for evaluation of tumor response to apatinib. Median PFS was 4.9 months (95% CI: 3.0-6.8 months). Six patients achieved partial response (PR); the objective response rate (ORR) was 16.7% (6/36), and the total disease control rate (DCR) was 77.8% (28/36). Followed up to March 2020, 35 of the 38 patients were dead, and the 1-year survival rate was 21.1% (8/38). The median overall survival (OS) was 6.9 months (95% CI: 5.2-8.5 months). The most common adverse events included fatigue (50.0%), hypertension (42.1%), proteinuria (23.7%), loss of appetite (23.1%) and hand-foot reaction (21.1%). No grade 4 adverse effect or drug-related mortality occurred.

Conclusions: Low-dose apatinib monotherapy might be an option for patients with advanced lung squamous-cell carcinoma.
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http://dx.doi.org/10.2147/OTT.S277532DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7667165PMC
November 2020

miR-19a/b and miR-20a Promote Wound Healing by Regulating the Inflammatory Response of Keratinocytes.

J Invest Dermatol 2021 Mar 16;141(3):659-671. Epub 2020 Sep 16.

Dermatology and Venereology Division, Department of Medicine Solna, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden; Unit of Dermatology, Karolinska University Hospital, Stockholm, Sweden; Ming Wai Lau Centre for Reparative Medicine, Stockholm node, Karolinska Institute, Stockholm, Sweden. Electronic address:

Persistent and impaired inflammation impedes tissue healing and is a characteristic of chronic wounds. A better understanding of the mechanisms controlling wound inflammation is needed. In this study, we show that in human wound-edge keratinocytes, the expressions of microRNA (miR)-17, miR-18a, miR-19a, miR-19b, and miR-20a, which all belong to the miR-17∼92 cluster, are upregulated during wound repair. However, their levels are lower in chronic ulcers than in acute wounds at the proliferative phase. Conditional knockout of miR-17∼92 in keratinocytes as well as injection of miR-19a/b and miR-20a antisense inhibitors into wound edges enhanced inflammation and delayed wound closure in mice. In contrast, conditional overexpression of the miR-17∼92 cluster or miR-19b alone in mice keratinocytes accelerated wound closure in vivo. Mechanistically, miR-19a/b and miR-20a decreased TLR3-mediated NF-κB activation by targeting SHCBP1 and SEMA7A, respectively, reducing the production of inflammatory chemokines and cytokines by keratinocytes. Thus, miR-19a/b and miR-20a being crucial regulators of wound inflammation, the lack thereof may contribute to sustained inflammation and impaired healing in chronic wounds. In line with this, we show that a combinatory treatment with miR-19b and miR-20a improved wound healing in a mouse model of type 2 diabetes.
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http://dx.doi.org/10.1016/j.jid.2020.06.037DOI Listing
March 2021

miR-145 attenuates cardiac fibrosis through the AKT/GSK-3β/β-catenin signaling pathway by directly targeting SOX9 in fibroblasts.

J Cell Biochem 2021 Feb 5;122(2):209-221. Epub 2020 Sep 5.

Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.

Myocardial infarction (MI) will inevitably result in cardiac fibrosis. In this study, we investigated the effect of microRNA-145 (miR-145) and transcription factor sex-determining region Y box 9 (SOX9) in the production of cardiac fibrosis induced by MI. MI rat models were established by left anterior descending coronary artery (LAD) occlusion. Four weeks after LAD, the cardiac fibrosis level was assessed by Masson's trichrome staining. Cardiac fibroblasts (CFs) exposed to hypoxia were used to simulate MI-induced fibrosis. Flow cytometry, cell counting kit-8, and transwell assays were used to examine changes in CF apoptosis, proliferation, and migration, respectively. miR-145 expression was measured by quantitative real-time polymerase chain reaction. Immunofluorescence and Western blot analysis were performed to determine the relative expression of proteins. In comparison to the sham-operated group, the expression of miR-145 was significantly downregulated in the infarction peripheral area, whereas, SOX9 was upregulated. In the infarcted heart, the overexpression of miR-145 significantly ameliorated cardiac fibrosis and cardiac function, and there was a negative correlation between miR-145 and SOX9 expressions in hypoxic CFs in vitro. In addition, SOX9 was verified to be a functional target of miR-145. Overexpression of miR-145 or inhibition of SOX9 decreased CF proliferation, migration, and fibrosis, but augmented their apoptotic rate. Moreover, the upregulation of miR-145 or suppression of SOX9 inhibited AKT and β-catenin signaling in hypoxic CFs. Taken together, this study highlights a potential treatment for cardiac fibrosis through the targeted regulation of SOX9 by miR-145, and our findings indicate that miR-145 exerts anti-fibrotic effects in MI via the negative regulation of SOX9 and its downstream AKT/GSK-3β/β-catenin pathways.
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http://dx.doi.org/10.1002/jcb.29843DOI Listing
February 2021

Electrically controllable cargo delivery with dextran-rich droplets.

J Colloid Interface Sci 2021 Jan 11;582(Pt A):102-111. Epub 2020 Aug 11.

Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. Electronic address:

The controllable delivery of cargo is of great importance in many areas, ranging from medicine and materials science to food and cosmetic industries. To fulfil the requirements in different areas, the development of new methods for cargo delivery in a controllable manner is always essential. A novel technique of cargo delivery controlled by electric pulse was developed in this paper. In an aqueous two-phase system, the dextran-rich droplets were fabricated as droplet carriers in a continuous polyethylene glycol-rich phase. The loading and releasing of model cargos (polystyrene particles) across the surface of the droplet carriers under electric pulses were demonstrated in microfluidic chips. By controlling the amplitude of the applied electric pulses, the cargos with designed sizes were sorted and loaded into the droplet carriers; hence, the targeted delivery of cargos by size can be achieved. The exchange of cargos between droplet carriers under reversed electric pulses was also investigated, and the results indicated the flexibility of this method in cargo delivery. Moreover, possible application of this method to biological cargos was demonstrated by controlling the loading and releasing of yeast cells under electric pulses. With the advantages of easy operation and fast response, this approach provides a novel route for controllable cargo delivery with droplets.
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http://dx.doi.org/10.1016/j.jcis.2020.08.033DOI Listing
January 2021

Nanoparticle and microorganism detection with a side-micron-orifice-based resistive pulse sensor.

Analyst 2020 Aug 24;145(16):5466-5474. Epub 2020 Jun 24.

Department of Marine Engineering, Dalian Maritime University, Dalian, 116026, China.

This paper presents the detection of nanoparticles and microorganisms using a recently developed side-orifice-based resistive pulse sensor (SO-RPS). By decreasing the channel height of the detection section of the SO-RPS, the detection sensitivity was increased and an average signal to noise ratio (S/N) of about 3 was achieved for 100 nm polystyrene particles. It was also found that spherical particles generate symmetrical signals. Algae with irregular shapes generate signals with more complex patterns. A scatter plot of signal magnitude versus signal width was proven to be reliable for differentiating bacteria from the nanoparticles and two types of algae. The side orifice for detecting heterogeneous nanoparticles and microorganisms is advantageous to avoid orifice clogging and the large flow resistance.
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http://dx.doi.org/10.1039/d0an00679cDOI Listing
August 2020

Short- and long-term outcomes of laparoscopic surgery for elderly patients with clinical stage I endometrial cancer.

J BUON 2020 Mar-Apr;25(2):764-771

Department of Gynecologic Oncosurgery, Jilin Provincial Cancer Hospital, Changchun, Jilin 130012, People's Republic of China.

Purpose: The purpose of this study was to compare the short- and long-term outcomes of laparoscopic surgery in elderly and middle-aged patients with clinical stage I endometrial cancer.

Methods: The clinical and follow-up data of 173 patients who were admitted to our hospital due to clinical stage I endometrial cancer and underwent laparoscopic surgery between January 2010 and December 2017 were retrospectively analyzed. The short- and long-term outcomes (including tumor recurrence, disease-free survival rate, and overall survival rate) of the elderly group (≥ 70 years, 69 patients) and the middle-aged group (50-69 years, 104 patients) were compared.

Results: In terms of preoperative general data comparison, only the Charlson comorbidity index and American Society of Anesthesiologists (ASA) score were higher in the elderly group than in the middle-aged group; differences in the remaining preoperative data were not statistically significant. Differences in general data, such as the operation time, proportion of patients that underwent lymphadenectomy, intraoperative blood loss, incidence and severity of postoperative 30-day complications, and pathological results were not statistically significant between the two groups. Long-term follow-up results showed that the two groups had similar tumor recurrence rates, as well as similar overall and disease-free survival rates. Multivariate analysis indicated that age was not an independent predictor for either overall or disease-free survival.

Conclusions: The use of laparoscopic surgery for elderly patients with clinical stage I endometrial cancer can achieve short- and long-term outcomes similar to those of middle-aged patients. Advanced age is not a contraindication to laparoscopic surgery.
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February 2021

Detecting zeta potential of polydimethylsiloxane (PDMS) in electrolyte solutions with atomic force microscope.

J Colloid Interface Sci 2020 Oct 2;578:116-123. Epub 2020 Jun 2.

Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada. Electronic address:

Zeta potential of PDMS-liquid interface is an important parameter for generating electroosmotic flow in a PDMS microchannel. In this paper, the zeta potentials of a PDMS slab in contacting with electrolyte solutions were evaluated with an atomic force microscope (AFM). As a colloidal probe of the AFM approaches to the surface of a PDMS slab in an electrolyte solution, a force curve is obtained and used to calculate the zeta potential of the PDMS. The effects of the plasma treating time and the aging of the electrolyte solutions on the zeta potential of PDMS surfaces were examined. The experimental results show that the air plasma treating time does not change the zeta potential of PDMS appreciably. Furthermore, the decreased zeta potential of a plasma-treated PDMS in an electrolyte solution is due to liquid aging, not the PDMS itself. Such characteristics probed by AFM provide new understanding of the surface charges of PDMS in electrolyte solutions.
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http://dx.doi.org/10.1016/j.jcis.2020.05.061DOI Listing
October 2020

Comparison of skeletal and soft tissue pericytes identifies CXCR4 bone forming mural cells in human tissues.

Bone Res 2020 22;8:22. Epub 2020 May 22.

Departments of Pathology, Johns Hopkins University, Baltimore, 21205 MD USA.

Human osteogenic progenitors are not precisely defined, being primarily studied as heterogeneous multipotent cell populations and termed mesenchymal stem cells (MSCs). Notably, select human pericytes can develop into bone-forming osteoblasts. Here, we sought to define the differentiation potential of CD146 human pericytes from skeletal and soft tissue sources, with the underlying goal of defining cell surface markers that typify an osteoblastogenic pericyte. CD146CD31CD45 pericytes were derived by fluorescence-activated cell sorting from human periosteum, adipose, or dermal tissue. Periosteal CD146CD31CD45 cells retained canonical features of pericytes/MSC. Periosteal pericytes demonstrated a striking tendency to undergo osteoblastogenesis in vitro and skeletogenesis in vivo, while soft tissue pericytes did not readily. Transcriptome analysis revealed higher CXCR4 signaling among periosteal pericytes in comparison to their soft tissue counterparts, and CXCR4 chemical inhibition abrogated ectopic ossification by periosteal pericytes. Conversely, enrichment of CXCR4 pericytes or stromal cells identified an osteoblastic/non-adipocytic precursor cell. In sum, human skeletal and soft tissue pericytes differ in their basal abilities to form bone. Diversity exists in soft tissue pericytes, however, and CXCR4 pericytes represent an osteoblastogenic, non-adipocytic cell precursor. Indeed, enrichment for CXCR4-expressing stromal cells is a potential new tactic for skeletal tissue engineering.
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http://dx.doi.org/10.1038/s41413-020-0097-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7244476PMC
May 2020

Quantitative viability detection for a single microalgae cell by two-level photoexcitation.

Analyst 2020 Jun 21;145(11):3931-3938. Epub 2020 Apr 21.

Center of Microfluidic Optoelectronic Sensing, Dalian Maritime University, Dalian, 116026, China.

A novel method for quantitative detection of the viability of a single microalgae cell by two-level photoexcitation is proposed in this paper. This method overcomes the difficulty of traditional methods in determining the cell viability by a fixed standard under a single photoexcitation. It is experimentally confirmed that this method is not limited by the species, morphology, size and structure of microalgae cells. An evaluation criterion of universal applicability is presented for the assessment of cell viability based on the large amount of experimental data. To the best of our knowledge, this is the first time that the relative fluorescence yield ratio F has been used to characterize the viability of single microalgae cells during cell migration. By using the relative fluorescence yield ratio, this method does not require the intensity of the excitation light to be very low for the assessment of the fluorescence yield of a dark-adapted microalgae cell, nor to be very strong to reach the saturated light level to assess the maximum fluorescence yield. Therefore, this method greatly reduces the technical difficulties of developing a sensor device. Well balanced portability, accuracy and universal applicability make it suitable for on-site real-time detection.
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http://dx.doi.org/10.1039/d0an00450bDOI Listing
June 2020

Ovatodiolide exerts anticancer effects on human cervical cancer cells via mitotic catastrophe, apoptosis and inhibition of NF-kB pathway.

J BUON 2020 Jan-Feb;25(1):87-92

Department of Radiotherapy and Jilin Cancer Hospital, Changchun, Jilin 130012, China.

Purpose: Being the second most prevalent cancer in females, cervical cancer causes significant mortality across the globe. Owing to the adverse effects and inefficiency of the currently used anticancer drugs, there are increasing efforts for the identification of safer and effective anticancer agents from plants. This study was undertaken to investigate the anticancer effects of Ovatodiolide, a plant-derived macrocyclic diterpenoid, against the human cervical cancer.

Methods: The anticancer effects were examined by WST-1 proliferation assay. DAPI and annexin V/propidium iodide (PI) staining were used for apoptosis detection. Flow cytometry was used for cell cycle analysis. Protein expression was used for cell cycle analysis.

Results: The results revealed that Ovatodiolide caused inhibition of the viability of all the cervical cancer cells with IC50 ranging from to 14 to 56 µM. Ovatodiolide exerted more profound antiproliferative effects on the DoTc2 cells with and IC50 of 14 µM. However, minimal cytotoxicity was observed for the normal cervical cells as evidenced from the IC50 of 100 µM. Ovatodiolide triggered apoptotic cell death of the DoTc2 cells. The induction of apoptosis was accompanied with increase in Bax and decrease in Bcl-2 expression. Ovatodiolide also caused arrest of the DoTc2 cells at the G2/M phase of the cell cycle, which was also accompanied with suppression of cyclin B1 expression. Investigation of the effects of Ovatodiolide on NF-kB expression revealed that the molecule caused significant decrease in the expression of the NF-kB expression.

Conclusion: Taken together, Ovatodiolide may prove a lead molecule for the development of systemic therapy for cervical cancer.
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December 2020

Circular RNA hsa_circ_0084443 Is Upregulated in Diabetic Foot Ulcer and Modulates Keratinocyte Migration and Proliferation.

Adv Wound Care (New Rochelle) 2020 04 7;9(4):145-160. Epub 2020 Feb 7.

Dermatology and Venereology Unit, Department of Medicine (Solna), Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.

Insufficient knowledge about the molecular pathology of diabetic foot ulcer (DFU) impedes the development of effective wound treatment. Circular RNAs (circRNAs) are a novel class of RNA recently discovered to be widely expressed and have important biological functions; however, their role in skin wound healing remains largely unexplored. In this study, we investigated the role of circRNAs in DFU. CircRNA expression was profiled in normal wounds (NWs) and DFUs by microarray analysis, and hsa_circ_0084443 was identified as differentially expressed. The circularity and subcellular localization of hsa_circ_0084443 were characterized by northern blotting, real-time PCR, and fluorescence hybridization. Cell migration, cell growth, and the transcriptome of human primary keratinocytes were analyzed after overexpression or RNA interference of hsa_circ_0084443. hsa_circ_0084443 is downregulated in NWs compared with intact skin, and its level is higher in DFUs than NWs. We confirmed its circularity and presence in the cytoplasm of human epidermal keratinocytes. We showed that hsa_circ_0084443 reduced motility while enhancing the growth of keratinocytes. Furthermore, we identified a gene network with the potential to mediate the biological effect of hsa_circ_0084443. CircRNAs have a functional role and a potential clinical significance in skin wound healing. We identified hsa_circ_0084443, a circRNA downregulated during NW healing, as a negative regulator of keratinocyte migration. Higher levels of hsa_circ_0084443 were detected in DFU samples, suggesting that it plays a role in pathology. These findings pave the way to understanding the functional role of circRNAs in human skin wound healing.
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http://dx.doi.org/10.1089/wound.2019.0956DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7047102PMC
April 2020

Plasma level of miR-99b may serve as potential diagnostic and short-term prognostic markers in patients with acute cerebral infarction.

J Clin Lab Anal 2020 Mar 22;34(3):e23093. Epub 2020 Jan 22.

Department of Respiratory Critical, Wuhan No. 6 Hospital, Wuhan, China.

Objective: The aim of the present study is to explore the potential diagnostic and prognostic value of plasma levels of miR-99 family for patients with acute cerebral infarction (ACI).

Methods: A total of 112 patients who have been diagnosed with ACI were enrolled in this study, and 112 healthy volunteers were served as the controls. The plasma of the patients and controls were collected, and total RNAs were isolated, and the expression levels of miR-99a, miR-99b, and miR-100 in the plasma of patients and controls were compared determined by RT-qPCR methods; moreover, the receiver operating characteristic (ROC) curve has been drawn to determine whether the plasma levels of miR-99b can distinguish patients with ACI from the controls; furthermore, the short-term prognosis of the patients was evaluated by glasgow outcome scale (GOS), and the correlation between the plasma levels of miR-99b and the GOS of the patients was evaluated. Finally, the correlation between the plasma level of miR-99 and VEGF of ACI patients was analyzed.

Results: It was observed that miR-99b was significantly decreased in the plasma of ACI patients compared with the healthy controls (P < .01), while the plasma levels of miR-99a and miR-100 showed no significant differences between the patients with ACI and the healthy controls; moreover, the area under the curve (AUC) of miR-99b for the diagnosis of ACI was 0.8882 (95% confidence interval (CI), 0.8451-0.9313), suggesting that plasma level of miR-99b is a sensitive marker to distinguish patients with ACI from the healthy volunteers; furthermore, the serum level of miR-99b was negatively correlated with GOS score of the patients (r = -.56, P < .001); finally, the plasma level of miR-99b was negatively correlated with the levels of VEGF (r = -.3013, P = .0012).

Conclusion: miR-99b was down-regulated in plasma of patients with ACI, and plasma level of miR-99b may be a potential diagnostic and prognostic marker for the diagnosis and treatment of ACI.
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http://dx.doi.org/10.1002/jcla.23093DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7083409PMC
March 2020

Influence of Water Content on Mechanical Strength and Microstructure of Alkali-Activated Fly Ash/GGBFS Mortars Cured at Cold and Polar Regions.

Materials (Basel) 2019 Dec 29;13(1). Epub 2019 Dec 29.

State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.

Negative temperature curing is a very harmful factor for geopolymer mortar or concrete, which will decrease the strength and durability. The water in the geopolymer mixture may be frozen into ice, and the water content is a crucial factor. The purpose of this paper is to explore the influence of water content on the properties of alkali-activated binders mortar cured at -5 °C. Fly ash (FA) and ground granulated blast furnace slag (GGBFS) were used as binders. Three groups of experiments with different water content were carried out. The prepared samples were investigated through uniaxial compression strength test, Scanning electron microscopy (SEM), and X-ray diffraction (XRD) for the determination of their compressive strength, microstructural features, phase, and composition. The results indicated that, the compressive strength of samples basically maintained 25.78 MPa-27.10 MPa at an age of 28 days; for 90 days, the values reached 33.4 MPa-34.04 MPa. The results showed that lower water content is beneficial to improving the early strength of mortar at -5 °C curing condition, while it has little impact on long-term strength. These results may provide references for the design and construction of geopolymer concrete in cold regions.
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http://dx.doi.org/10.3390/ma13010138DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6982226PMC
December 2019

Polyelectrolyte adsorption in single small nanochannel by layer-by-layer method.

Authors:
Jun Li Dongqing Li

J Colloid Interface Sci 2020 Mar 29;561:1-10. Epub 2019 Nov 29.

Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. Electronic address:

Nanochannel size control by using layer-by-layer (LBL) deposition of polyelectrolytes is experimentally studied in single hard Polydimethylsiloxane (PDMS) nanochannel. Electroosmotic flow (EOF) velocity is measured by using the current-slope method in the modified nanochannel with various numbers of the deposition layers. The results reveal that the growth of polyelectrolyte layer in nanochannels is quite different from that on flat substrates. In small nanochannels, the increment of the multilayer thickness will be limited unlike that on flat surfaces. As the number of the deposition layers increases, the nanochannel size will decrease initially and reach a saturation value finally where the nanochannel cannot be filled with the polyelectrolytes. It is observed that both the decrement and the saturation value of the nanochannel size strongly depend on the concentration of the salt addition in polyelectrolyte solutions. At low ionic concentration, increasing the salt addition increases the average layer thickness within the nanochannels and decreases the saturation value of nanochannel size. However, the effects of salt addition can demonstrate opposite behaviors at high ionic concentration. The EOF can be alternatively reversed in the modified nanochannels by repeatedly coating oppositely charged polyelectrolytes, and the EOF velocity will gradually decrease with the increasing deposition cycles.
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http://dx.doi.org/10.1016/j.jcis.2019.11.116DOI Listing
March 2020

Metabolomics study of serum and urine samples reveals metabolic pathways and biomarkers associated with pelvic organ prolapse.

J Chromatogr B Analyt Technol Biomed Life Sci 2020 Jan 14;1136:121882. Epub 2019 Nov 14.

Nanchang University, Nanchang 330006, Jiangxi, China; Key Laboratory of Women's Reproductive Health of Jiangxi Province, Jiangxi Provincial Maternal and Child Health Hospital, Nanchang 330006, Jiangxi, China. Electronic address:

Pelvic organ prolapse (POP) is a common medical condition among women and involves complicated diagnostics and controversial surgical management. The exact molecular mechanism underlying POP is poorly understood, especially at the metabolism level. To explore the metabolic mechanism underlying POP and discover potential biomarkers for POP diagnosis, we applied a non-targeted metabolomics approach using ultra-high performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UHPLC-Q-TOF-MS). Metabolomics study of serum samples from patients with POP (n = 24) and controls (n = 22) revealed a total of 59 metabolites that are significantly different (VIP ≥ 1 and p ≤ 0.05) between the two groups. Between urine samples from POP patients (n = 45) and controls (n = 59), 33 metabolites differed significantly (VIP ≥ 1 and p ≤ 0.05). Metabolic pathways affected by these differentially expressed metabolites were analyzed. In both serum and urine samples, three pathways including arginine biosynthesis and purine metabolism were found to be significantly related to POP. Six metabolites including GPC, 1-methyladenosine, maleic acid, L-pyroglutamic acid, inosine, and citrate are significantly changed (VIP ≥ 1 and p ≤ 0.05) in both serum and urine samples from patients with POP. Receiver operating characteristics (ROC) curve analysis showed that using these six metabolites as a biomarker could distinguish patients with POP from controls with good accuracy in both serum (AUC = 1) and urine samples (AUC = 0.854). Collectively, these results further extended our understanding of key regulatory metabolic pathways involved in the pathophysiology of POP, as well as provided some promising biomarkers for effective POP diagnosis.
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http://dx.doi.org/10.1016/j.jchromb.2019.121882DOI Listing
January 2020

Bidirectional transfer of particles across liquid-liquid interface under electric pulse.

J Colloid Interface Sci 2020 Feb 24;560:436-446. Epub 2019 Oct 24.

Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. Electronic address:

Hypothesis: The controllable transfer of colloidal particles across liquid-liquid interfaces has attracted great interests in synthesis of new materials and stabilization of emulsions. Can we find new ways of controlled transferring particles across liquid-liquid interface with reversible transfer directions and size manipulation?

Experiments: A technique of bidirectional transfer of colloidal particles in an aqueous two-phase system (ATPS) under electric pulse was developed. The influences of electric pulse, ATPS composition, surfactant concentration, ionic strength and particle size on the particle transfer were investigated systematically.

Findings: Under electric pulses, particles overcome the energy barrier at the liquid-liquid interface and transfer into the other phase. The action of particle transfer is determined by the voltage of electric pulse, and the transfer direction is reversible by exchanging the direction of electric pulse. The ATPS composition, surfactant concentration, ionic strength and particle size affect the particle transfer by changing the free energy of particle detachment. With this method, the targeted transfer of particles by size can be realized by controlling the strength of electric pulse. The proposed method provides a promising technique for transfer of particles across liquid-liquid interface with advantages of fast response and precise control.
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http://dx.doi.org/10.1016/j.jcis.2019.10.091DOI Listing
February 2020

Estimation of hydraulic conductivity of saturated frozen soil from the soil freezing characteristic curve.

Sci Total Environ 2020 Jan 30;698:134132. Epub 2019 Aug 30.

State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China.

Knowledge of hydraulic conductivity is crucial for determining water movement in frozen soil, and the objective of this study is to introduce the soil freezing characteristic curve to estimate the hydraulic conductivity of saturated frozen soil. Based on the non-uniform tortuous capillary bundle model and the assumption that the ice was first formed in the pores with largest size, a physical infiltration model of saturated frozen soil was developed. On the basis of this physical infiltration model, a new approach for estimating the hydraulic conductivity of saturated frozen soil was developed by using the Hagen-Poiseuille equation and Darcy's law. To verify the validity of this approach, five soil data sets, including 29 data points with hydraulic conductivity between 10 cm/s and 10 cm/s, were used to compare the predicted results and experimental data. The results show that the new approach fits the experimental data well. This approach is more convenient than the soil water characteristic curve in numerical modeling, and it can be used to describe the relationship between hydraulic conductivity and minus temperature. Moreover, the new approach and the results in this study maybe also can provide a reference for the research on water flow and the related numerical modeling in cold regions environmental engineering.
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http://dx.doi.org/10.1016/j.scitotenv.2019.134132DOI Listing
January 2020

Zeta potentials of PDMS surfaces modified with poly(ethylene glycol) by physisorption.

Electrophoresis 2020 06 13;41(10-11):761-768. Epub 2019 Sep 13.

Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Canada.

Controlling zeta potential of PDMS surface coated with a layer of PEG is important for electroosmosis and electrophoresis in PDMS made microfluidic chips. Here, zeta potentials of PDMS surfaces modified by simple physisorption of PEG of different concentrations in phosphate buffer solutions, pure water, and PEG solution were reported. Coating PEG on PDMS surfaces was achieved by immersing a PDMS layer into the PEG solution for 10 min and then taking it out and placing it in an oven at 80℃ for 10 h. To avoid damaging the PEG layer on the PDMS surface, an induction current method was employed for zeta potential measurement. Zeta potentials of PEG modified PDMS in electrolyte solutions were measured. The results show that 2.5% PEG can effectively modify PDMS surface with positive zeta potential value in phosphate buffer solutions, pure water and 10% PEG solution. Further increase in PEG solution beyond 5% for surface modification has no obvious effect on zeta potential change.
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http://dx.doi.org/10.1002/elps.201900246DOI Listing
June 2020

MicroRNA-34 Family Enhances Wound Inflammation by Targeting LGR4.

J Invest Dermatol 2020 02 31;140(2):465-476.e11. Epub 2019 Jul 31.

Dermatology and Venereology Division, Department of Medicine (Solna), Karolinska Institute, Stockholm, Sweden; Ming Wai Lau Centre for Reparative Medicine, Stockholm node, Karolinska Institute, Stockholm, Sweden. Electronic address:

Venous ulcers are the most common type of human chronic nonhealing wounds and are stalled in a constant and excessive inflammatory state. The molecular mechanisms underlying the chronic wound inflammation remain elusive. Moreover, little is known about the role of regulatory RNAs, such as microRNAs, in the pathogenesis of venous ulcers. We found that both microRNA (miR)-34a and miR-34c were upregulated in the wound-edge epidermal keratinocytes of venous ulcers compared with normal wounds or the skin. In keratinocytes, miR-34a and miR-34c promoted inflammatory chemokine and cytokine production. In wounds of wild-type mice, miR-34a-mimic treatment enhanced inflammation and delayed healing. To further explore how miR-34 functions, LGR4 was identified as a direct target mediating the proinflammatory function of miR-34a and miR-34c. Interestingly, impaired wound closure with enhanced inflammation was also observed in Lgr4 knockout mice. Mechanistically, the miR-34-LGR4 axis regulated GSK-3β-induced p65 serine 468 phosphorylation, changing the activity of the NF-κB signaling pathway. Collectively, the miR-34-LGR4 axis was shown to regulate keratinocyte inflammatory response, the deregulation of which may play a pathological role in venous ulcers.
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http://dx.doi.org/10.1016/j.jid.2019.07.694DOI Listing
February 2020

Electroosmotic flow velocity in DNA modified nanochannels.

Authors:
Jun Li Dongqing Li

J Colloid Interface Sci 2019 Oct 3;553:31-39. Epub 2019 Jun 3.

Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. Electronic address:

Electroosmotic flow (EOF) is systematically investigated in DNA grafted hard PDMS (h-PDMS) channels with size ranging from 50 nm to 2.5 μm by using the current-slope method. The effects of the DNA types, the incubation time in the process of surface modification, and the pH value, ionic concentration of electrolyte solutions, and the UV (ultraviolet) illumination on the velocity of electroosmotic flow are experimentally studied. It is found that the DNA type and the incubation time of DNAs affect the grafting density and the surface charge on the channel walls, thus influencing the EOF velocity. In the DNA modified channels, the pH effects on EOF velocity become less prominent compared with that in the pristine channels. On the contrary, UV illumination can increase the EOF velocity significantly in the DNA modified channels, whereas takes unapparent effects on EOF velocity in the pristine channels. The effects of ionic concentration on EOF are also studied in this paper. It is observed that EOF velocity is dependent on the channel size when the ionic concentration is low even without overlapped electric double layer (EDL) and is essentially independent of the channel size when the ionic concentration is high. Furthermore, with high ionic concentration and thin EDL, the EOF velocity can be enhanced by the coated DNA brushes on the channel surface.
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http://dx.doi.org/10.1016/j.jcis.2019.06.002DOI Listing
October 2019

Human skin long noncoding RNA WAKMAR1 regulates wound healing by enhancing keratinocyte migration.

Proc Natl Acad Sci U S A 2019 05 24;116(19):9443-9452. Epub 2019 Apr 24.

Dermatology and Venereology Division, Department of Medicine (Solna), Center for Molecular Medicine, Karolinska Institute, 17176 Stockholm, Sweden;

An increasing number of studies reveal the importance of long noncoding RNAs (lncRNAs) in gene expression control underlying many physiological and pathological processes. However, their role in skin wound healing remains poorly understood. Our study focused on a skin-specific lncRNA, LOC105372576, whose expression was increased during physiological wound healing. In human nonhealing wounds, however, its level was significantly lower compared with normal wounds under reepithelialization. We characterized LOC105372576 as a nuclear-localized, RNAPII-transcribed, and polyadenylated lncRNA. In keratinocytes, its expression was induced by TGF-β signaling. Knockdown of LOC105372576 and activation of its endogenous transcription, respectively, reduced and increased the motility of keratinocytes and reepithelialization of human ex vivo skin wounds. Therefore, LOC105372576 was termed "wound and keratinocyte migration-associated lncRNA 1" (WAKMAR1). Further study revealed that WAKMAR1 regulated a network of protein-coding genes important for cell migration, most of which were under the control of transcription factor E2F1. Mechanistically, WAKMAR1 enhanced E2F1 expression by interfering with E2F1 promoter methylation through the sequestration of DNA methyltransferases. Collectively, we have identified a lncRNA important for keratinocyte migration, whose deficiency may be involved in the pathogenesis of chronic wounds.
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http://dx.doi.org/10.1073/pnas.1814097116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6511036PMC
May 2019

Continuous Cell Characterization and Separation by Microfluidic Alternating Current Dielectrophoresis.

Anal Chem 2019 05 22;91(9):6304-6314. Epub 2019 Apr 22.

Department of Mechanical and Mechatronics Engineering , University of Waterloo , Waterloo , Ontario , Canada , N2L 3G1.

A novel alternating current (ac)-dielectrophoretic (DEP) microfluidic chip for continuous cell characterization and separation is presented in this paper. To generate DEP forces, two electrode-pads are embedded in a set of asymmetric orifices on the opposite sidewalls to produce the nonuniform electric fields. In the vicinity of a small orifice, the cells experience the strongest nonuniform gradient and are drawn toward it by the positive DEP forces, while the cells experiencing a negative DEP force are repelled away and move toward the large orifice. The DEP behaviors of yeast cells in suspending media with different ionic concentrations, i.e., different electrical conductivities, and over a large range of the ac electric field frequency were investigated. Furthermore, the lateral migrations of yeast cells as a function of the ac frequency were measured. The trends of measured lateral migrations of yeast cells are similar to the corresponding Clausius-Mossotti (CM) factors. In addition, by adjusting the frequency and strength of the ac electric field, the continuous separation of live and dead yeast cells as well as the yeast cells with targeted diameter and dielectric property can be easily achieved. This is the first time that the measurement of ac-DEP lateral migration of yeast cells in solutions with different electrical conductivities as a function of the applied frequency in a microfluidic chip was reported. This ac-DEP system provides a method to characterize the crossover frequency of the specific cells and manipulate the targeted cells.
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http://dx.doi.org/10.1021/acs.analchem.9b01104DOI Listing
May 2019

Coalescence of a Water Drop with an Air-Liquid Interface: Electric Current Generation and Critical Micelle Concentration (CMC) Sensing Application.

ACS Appl Mater Interfaces 2019 May 24;11(18):16981-16990. Epub 2019 Apr 24.

Department of Mechanical and Mechatronics Engineering , University of Waterloo , Waterloo , ON N2L 3G1 , Canada.

A phenomenon that electric current is generated when a pendant water droplet touches an air-electrolyte solution interface is investigated in this paper. A measurement system developed in this study consists of a hollow electrode for droplet generation, a counter electrode immersed in an electrolyte solution, and an electrometer with high precision. Once a droplet touches the air-electrolyte solution interface, it will be pulled into the electrolyte solution and an electric current is produced during this process. Experiments showed that the magnitude of the electric current depends only on the pendant droplet and has nothing to do with the types of the electrolyte solution (with a much larger volume than that of the droplet) below the drop. The electric current is generated by the electric potential difference between the droplet and air-electrolyte solution interface and the liquid bridge formed during droplet coalescence. As a result, the magnitude of the generated electrical current mainly depends on the size, pH, and the type of the solution forming the droplet. Determining the critical micelle concentration using this system was successfully achieved to show the powerfulness of this system.
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http://dx.doi.org/10.1021/acsami.9b00365DOI Listing
May 2019