Dynamic Modeling of Fluid Flow within Three-Dimensional Perfusion Bioreactor

Three-dimensional perfusion bioreactors have been shown to enhance cell viability and function through improved nutrient exchange. However, the ideal bioreactor scaffold geometry is still unknown. The focus of this study is to use computational fluid flow studies to inform bioreactor design. Specifically, we will model the effect of bioreactor design on fluid shear stress and then correlate these values with stem cell viability in the bioreactor. Previous studies have shown that the maximum shear stress level for the viability of human mesenchymal stem cells (hMSCs) is 0.3 dynes/cm2. Two distinct Computer Aided Design models were created consisting of parallel planes of pillars (0.5 mm diameter, 2 mm height) in a linear array with 1 mm center to center spacing. One design consists of seven horizontal layers inserted into a 3D printed housing while the other consists of five layers encapsulated by a cylinder matching the inner diameter of silicon tubing (0.5 in). For in vitro testing, both scaffold designs were created by 3D printing and were coated with collagen to facilitate hMSC adhesion. To quantify results, hMSCs were harvested from the scaffolds for analyses by picogreen DNA quantification for total DNA and cell viability, and immunohistochemical markers for stem cell population maintenance. In the effort to establish a predictive model, we will compare the flow simulation results to the degree of cell proliferation in the bioreactor experiment. The significance of cell proliferation will indicate further improvements on the bioreactor design

Genes That Influence Swarming Motility and Biofilm Formation in Variovorax paradoxus EPS

Variovorax paradoxus is an aerobic soil bacterium associated with important biodegradative processes in nature. We use V. paradoxus EPS to study multicellular behaviors on surfaces.We recovered flanking sequence from 123 clones in a Tn5 mutant library, with insertions in 29 different genes, selected based on observed surface behavior phenotypes. We identified three genes, Varpa_4665, Varpa_4680, and Varpa_5900, for further examination. These genes were cloned into pBBR1MCS2 and used to complement the insertion mutants. We also analyzed expression of Varpa_4680 and Varpa_5900 under different growth conditions by qPCR.The 29 genes we identified had diverse predicted functions, many in exopolysaccharide synthesis. Varpa_4680, the most commonly recovered insertion site, encodes a putative N-acetyl-L-fucosamine transferase similar to WbuB. Expression of this gene in trans complemented the mutant fully. Several unique insertions were identified in Varpa_5900, which is one of three predicted pilY1 homologs in the EPS genome. No insertions in the two other putative pilY1 homologs present in the genome were identified. Expression of Varpa_5900 altered the structure of the wild type swarm, as did disruption of the chromosomal gene. The swarming phenotype was complemented by expression of Varpa_5900 from a plasmid, but biofilm formation was not restored. Both Varpa_4680 and Varpa_5900 transcripts were downregulated in biofilms and upregulated during swarming when compared to log phase culture. We identified a putative two component system (Varpa_4664-4665) encoding a response regulator (shkR) and a sensor histidine kinase (shkS), respectively. Biofilm formation increased and swarming was strongly delayed in the Varpa_4665 (shkS) mutant. Complementation of shkS restored the biofilm phenotype but swarming was still delayed. Expression of shkR in trans suppressed biofilm formation in either genetic background, and partially restored swarming in the mutant.The data presented here point to complex regulation of these surface behaviors

'The girl with her period is the one to hang her head' Reflections on menstrual management among schoolgirls in rural Kenya

<p>Abstract</p> <p>Background</p> <p>The onset of menstruation is a landmark event in the life of a young woman. Yet the complications and challenges that can accompany such an event have been understudied, specifically in resource-poor settings. As interventions aim to improve female attendance in schools, it is important to explore how menstruation is perceived and navigated by girls in the school setting. This research conveys rural Kenyan schoolgirls' perceptions and practices related to menstruation</p> <p>Methods</p> <p>Data were collected at six rural schools in the Nyanza Province of Western Kenya. Using focus group discussions, in-depth interviews, and field notes from observations, researchers collected information from 48 primary schoolgirls and nine teachers. Systematic analysis began with a reading of transcripts and debriefing notes, followed by manual coding of the narratives.</p> <p>Results</p> <p>Focus group discussions became opportunities for girls to share thoughts on menstruation, instruct one another on management practices and advise one another on coping mechanisms. Girls expressed fear, shame, distraction and confusion as feelings associated with menstruation. These feelings are largely linked to a sense of embarrassment, concerns about being stigmatized by fellow students and, as teachers explained, a perception that the onset of menstruation signals the advent of a girl's sexual status. Among the many methods for managing their periods, girls most frequently said they folded, bunched up or sewed cloth, including cloth from shirts or dresses, scraps of old cloth, or strips of an old blanket. Cloth was reported to frequently leak and cause chafing, which made school attendance difficult particularly as the day progressed. Attitudes and practices of girls toward menstruation have been arranged into personal, environmental and behavioural factors.</p> <p>Conclusion</p> <p>Further research on menstrual management options that are practical, sustainable and culturally acceptable must be conducted to inform future programs and policies that aim to empower young girls as they transition into womanhood. Stakeholders working within this and similar contexts must consider systematic mechanisms to explain to young girls what menstruation is and how to manage it. Providing sanitary supplies or guiding girls on how to create supplies serve as critical components for future interventions.</p

Fano Resonances in Flat Band Networks

Linear wave equations on Hamiltonian lattices with translational invariance are characterized by an eigenvalue band structure in reciprocal space. Flat band lattices have at least one of the bands completely dispersionless. Such bands are coined flat bands. Flat bands occur in fine-tuned networks, and can be protected by (e.g. chiral) symmetries. Recently a number of such systems were realized in structured optical systems, exciton-polariton condensates, and ultracold atomic gases. Flat band networks support compact localized modes. Local defects couple these compact modes to dispersive states and generate Fano resonances in the wave propagation. Disorder (i.e. a finite density of defects) leads to a dense set of Fano defects, and to novel scaling laws in the localization length of disordered dispersive states. Nonlinearities can preserve the compactness of flat band modes, along with renormalizing (tuning) their frequencies. These strictly compact nonlinear excitations induce tunable Fano resonances in the wave propagation of a nonlinear flat band lattice

Combination of SIRT1 and Src overexpression suggests poor prognosis in luminal breast cancer

Jie Tan,1,* Yuyin Liu,2,* Yusufu Maimaiti,3 Changwen Wang,1 Yu Yan,1 Jing Zhou,1 Shengnan Ruan,1 Tao Huang1 1Department of Breast and Thyroid Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; 2Department of Clinical Laboratory, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; 3Department of General Surgery, Research Institute of Minimally Invasive, People&rsquo;s Hospital of Xinjiang Uygur Autonomous Region, Urumqi, China *These authors contributed equally to this work Objectives: 1) Analyze the correlation of SIRT1 and Src with human breast cancer (BC) prognosis; 2) explore the roles of SIRT1 and Src in BC cell proliferation, tumor invasion, and metastasis; and 3) analyze the correlation and interaction between SIRT1 and Src. Materials and methods: 1) Tissue microarray was used to analyze the expression of SIRT1 and Src in human BC tissues and the correlation between protein expression and cancer prognosis; 2) CCK8 assay was used to determine the influence of SIRT1 and Src inhibitors on BC cell proliferation; 3) Transwell migration assay and wound healing assay were used to determine the effect of SIRT1 and Src inhibitors on BC cell migration and invasion; and 4) Western blotting was used to analyze the correlation and interaction between SIRT1 and Src. Results: 1) Combination of SIRT1 and/or Src positivity is a prognosis factor in BC, especially in luminal type; 2) MCF-7 cell proliferation is suppressed by SIRT1 inhibitor Ex527, and cell migration and invasion were inhibited by Src inhibitor bosutinib; 3) combined with Ex527, bosutinib has a significantly increased effect on MCF-7 cell migration suppression; and 4) there is a positive association between SIRT1 and Src both in BC tissues and in MCF-7 cells. Conclusion: 1) SIRT1 and Src overexpression are both correlated with poor prognosis in human BC; 2) SIRT1 + Src (SIRT1 and/or Src positivity) is a fine prognosis model for luminal-type BC; 3) SIRT1 is a copromotor of Src in BC migration and invasion, but not in cell proliferation; and 4) our results suggest a potential interaction or a common regulation pathway between SIRT1 and Src expression and activity. Keywords: breast cancer, SIRT1, Src, tissue microarray, estrogen receptor, cell migratio

Platelets Enhance Endothelial Adhesiveness in High Tidal Volume Ventilation

Although platelets induce lung inflammation, leading to acute lung injury (ALI), the extent of platelet–endothelial cell (EC) interactions remains poorly understood. Here, in a ventilation-stress model of lung inflammation, we show that platelet–EC interactions are important. We obtained freshly isolated lung endothelial cells (FLECs) from isolated, blood-perfused rat lungs exposed to ventilation at low tidal volume (LV) or stress-inducing high tidal volume (HV). Immunofluorescence and immunoprecipitation studies revealed HV-induced increases in cell-surface von Willebrand factor (vWf) expression on FLEC. This increased expression was inhibited by platelet removal from the lung perfusion and by including a P-selectin–blocking antibody in the lung perfusion. The expression was also blocked in lungs from P-selectin knockout (P sel−/−) mice perfused with autologous blood, but not with heterologous wild-type blood containing P-selectin–expressing platelets. These findings indicate that in ventilation stress, platelets transfer vWf to the EC surface and that platelet P-selectin plays a critical role in this transfer. Further evidence for such intercellular transfers was the HV-induced FLEC expressions of platelet glycoprotein 1b and of platelet P-selectin. We conclude that in ventilation stress, platelets deposit leukocyte- and platelet-binding proteins on the EC surface, thereby establishing the proinflammatory phenotype of the vascular lining

Angiotensin II Influences Pre-mRNA Splicing Regulation by Enhancing RBM20 Transcription Through Activation of the MAPK/ELK1 Signaling Pathway

RNA binding motif 20 (RBM20) is a key regulator of pre-mRNA splicing of titin and other genes that are associated with cardiac diseases. Hormones, like insulin, triiodothyronine (T3), and angiotensin II (Ang II), can regulate gene-splicing through RBM20, but the detailed mechanism remains unclear. This study was aimed at investigating the signaling mechanism by which hormones regulate pre-mRNA splicing through RBM20. We first examined the role of RBM20 in Z-, I-, and M-band titin splicing at different ages in wild type (WT) and RBM20 knockout (KO) rats using RT-PCR; we found that RBM20 is the predominant regulator of I-band titin splicing at all ages. Then we treated rats with propylthiouracil (PTU), T3, streptozotocin (STZ), and Ang II and evaluated the impact of these hormones on the splicing of titin, LIM domain binding 3 (Ldb3), calcium/calmodulin-dependent protein kinase II gamma (Camk2g), and triadin (Trdn). We determined the activation of mitogen-activated protein kinase (MAPK) signaling in primary cardiomyocytes treated with insulin, T3, and Ang II using western blotting; MAPK signaling was activated and RBM20 expression increased after treatment. Two downstream transcriptional factors c-jun and ETS Transcription Factor (ELK1) can bind the promoter of RBM20. A dual-luciferase activity assay revealed that Ang II, but not insulin and T3, can trigger ELK1 and thus promote transcription of RBM20. This study revealed that Ang II can trigger ELK1 through activation of MAPK signaling by enhancing RBM20 expression which regulates pre-mRNA splicing. Our study provides a potential therapeutic target for the treatment of cardiac diseases in RBM20-mediated pre-mRNA splicing