Carbon Dioxide Multiphase Flows in Microfluidic Devices

In this thesis, we experimentally studied the mass transfer during CO2 absorption into water, ethanol, methanol and silicone oil under slug flow in microchannels. We showed that the initial bubble size is determined by the liquid fraction and channel geometry, while the CO2 diffusion rate is determined by the gas pressure and liquid properties, such as the Henry\u27s constant and the diffusion coefficient. The reduction of the gas void fractionΑG along the flow direction and the transformation of segmented flows into dilute bubbly flows was observed and predicted. In high viscosity liquids, we showed the liquid film thickness is related to the capillary number and the gas pressure. We also constructed experimental setup for investigating CO2 cavitation in microchannels. A linear time dependence of bubble growth from depressurization is observed. In addition, we proposed the fabrication procedure of co-flowing capillary tip and listed its current limitations

A FreeSurfer-compliant consistent manual segmentation of infant brains spanning the 0-2 year age range

We present a detailed description of a set of FreeSurfer compatible segmentation guidelines tailored to infant MRI scans, and a unique data set of manually segmented acquisitions, with subjects nearly evenly distributed between 0 and 2 years of age. We believe that these segmentation guidelines and this dataset will have a wide range of potential uses in medicine and neuroscience.Eunice Kennedy Shriver National Institute of Child Health and Human Development (U.S.) (Grant 1K99HD061485-01A1)Eunice Kennedy Shriver National Institute of Child Health and Human Development (U.S.) (Grant R00 HD061485-03)Ralph Schlaeger FellowshipNational Institutes of Health (U.S.) (1R01EB014947-01)National Institutes of Health (U.S.) (K23 NS42758-01)National Center for Research Resources (U.S.) (P41-RR14075)National Center for Research Resources (U.S.) (U24 RR021382)National Institutes of Health. National Institute for Biomedical Imaging and Bioengineering (R01EB006758)National Institute on Aging (AG022381)National Institute on Aging (5R01AG008122-22)National Institute of Neurological Disorders and Stroke (U.S.) (R01 NS052585-01)National Institute of Neurological Disorders and Stroke (U.S.) (1R21NS072652-01)National Institute of Neurological Disorders and Stroke (U.S.) (1R01NS070963)National Center for Research Resources (U.S.) (Shared Instrumentation Grant 1S10RR023401)National Center for Research Resources (U.S.) (Shared Instrumentation Grant 1S10RR019307)National Center for Research Resources (U.S.) (Shared Instrumentation Grant 1S10RR023043)Ellison Medical FoundationNational Institutes of Health. Blueprint for Neuroscience Research (5U01-MH093765)Human Connectome Projec

Knockdown of astrocyte elevated gene-1 inhibits proliferation and enhancing chemo-sensitivity to cisplatin or doxorubicin in neuroblastoma cells

<p>Abstract</p> <p>Background</p> <p><it>Astrocyte elevated gene-1 </it>(<it>AEG</it>-<it>1</it>) was originally characterized as a HIV-1-inducible gene in primary human fetal astrocyte. Recent studies highlight a potential role of <it>AEG-1 </it>in promoting tumor progression and metastasis. The aim of this study was to investigate if <it>AEG-1 </it>serves as a potential therapeutic target of human neuroblastoma.</p> <p>Methods</p> <p>We employed RNA interference to reduce <it>AEG-1 </it>expression in human neuroblastoma cell lines and analyzed their phenotypic changes.</p> <p>Results</p> <p>We found that the knockdown of <it>AEG-1 </it>expression in human neuroblastoma cells significantly inhibited cell proliferation and apoptosis. The specific downregulation induced cell arrest in the G₀/G₁phase of cell cycle. In the present study, we also observed a significant enhancement of chemo-sensitivity to cisplatin and doxorubicin by knockdown of <it>AEG-1</it>.</p> <p>Conclusion</p> <p>Our study suggests that overexpressed <it>AEG-1 </it>enhance the tumorogenic properties of neuroblastoma cells. The inhibition of <it>AEG-1 </it>expression could be a new adjuvant therapy for neuroblastoma.</p

Three Capsular Polysaccharide Synthesis-Related Glucosyltransferases, GT-1, GT-2 and WcaJ, Are Associated With Virulence and Phage Sensitivity of Klebsiella pneumoniae

Klebsiella pneumoniae (K. pneumoniae) spp. are important nosocomial and community-acquired opportunistic pathogens, which cause various infections. We observed that K. pneumoniae strain K7 abruptly mutates to rough-type phage-resistant phenotype upon treatment with phage GH-K3. In the present study, the rough-type phage-resistant mutant named K7RR showed much lower virulence than K7. Liquid chromatography-tandem mass spectrometry (LC-MS-MS) analysis indicated that WcaJ and two undefined glycosyltransferases (GTs)- named GT-1, GT-2- were found to be down-regulated drastically in K7RR as compared to K7 strain. GT-1, GT-2, and wcaJ are all located in the gene cluster of capsular polysaccharide (CPS). Upon deletion, even of single component, of GT-1, GT-2, and wcaJ resulted clearly in significant decline of CPS synthesis with concomitant development of GH-K3 resistance and decline of virulence of K. pneumoniae, indicating that all these three GTs are more likely involved in maintenance of phage sensitivity and bacterial virulence. Additionally, K7RR and GT-deficient strains were found sensitive to endocytosis of macrophages. Mitogen-activated protein kinase (MAPK) signaling pathway of macrophages was significantly activated by K7RR and GT-deficient strains comparing with that of K7. Interestingly, in the presence of macromolecular CPS residues (&gt;250 KD), K7(ΔGT-1) and K7(ΔwcaJ) could still be bounded by GH-K3, though with a modest adsorption efficiency, and showed minor virulence, suggesting that the CPS residues accumulated upon deletion of GT-1 or wcaJ did retain phage binding sites as well maintain mild virulence. In brief, our study defines, for the first time, the potential roles of GT-1, GT-2, and WcaJ in K. pneumoniae in bacterial virulence and generation of rough-type mutation under the pressure of bacteriophage

Dissolution of carbon dioxide bubbles and microfluidic multiphase flows

We experimentally study the dissolution of carbon dioxide bubbles into common liquids (water, ethanol, and methanol) using microfluidic devices. Elongated bubbles are individually produced using a hydrodynamic focusing section into a compact microchannel. The initial bubble size is determined based on the fluid volumetric flow rates of injection and the channel geometry. By contrast, the bubble dissolution rate is found to depend on the inlet gas pressure and the fluid pair composition. For short periods of time after the fluids initial contact, the bubble length decreases linearly with time. We show that the initial rate of bubble shrinkage is proportional to the ratio of the diffusion coefficient and the Henry’s law constant associated with each fluid pair. Our study shows the possibility to rapidly impregnate liquids with CO2 over short distances using microfluidic technology

Novel sensing technology in fall risk assessment in older adults: a systematic review

Abstract Background Falls are a major health problem for older adults with significant physical and psychological consequences. A first step of successful fall prevention is to identify those at risk of falling. Recent advancement in sensing technology offers the possibility of objective, low-cost and easy-to-implement fall risk assessment. The objective of this systematic review is to assess the current state of sensing technology on providing objective fall risk assessment in older adults. Methods A systematic review was conducted in accordance to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement (PRISMA). Results Twenty-two studies out of 855 articles were systematically identified and included in this review. Pertinent methodological features (sensing technique, assessment activities, outcome variables, and fall discrimination/prediction models) were extracted from each article. Four major sensing technologies (inertial sensors, video/depth camera, pressure sensing platform and laser sensing) were reported to provide accurate fall risk diagnostic in older adults. Steady state walking, static/dynamic balance, and functional mobility were used as the assessment activity. A diverse range of diagnostic accuracy across studies (47.9% - 100%) were reported, due to variation in measured kinematic/kinetic parameters and modelling techniques. Conclusions A wide range of sensor technologies have been utilized in fall risk assessment in older adults. Overall, these devices have the potential to provide an accurate, inexpensive, and easy-to-implement fall risk assessment. However, the variation in measured parameters, assessment tools, sensor sites, movement tasks, and modelling techniques, precludes a firm conclusion on their ability to predict future falls. Future work is needed to determine a clinical meaningful and easy to interpret fall risk diagnosis utilizing sensing technology. Additionally, the gap between functional evaluation and user experience to technology should be addressed

The effect of the ketogenic diet on hippocampal GluR(5) and GluR(6) mRNA expression and Q/R site editing in the kainate-induced epilepsy model

Treatment with the ketogenic diet has been used to control refractory epilepsy for many years, although its anticonvulsant mechanism is unknown. By modulating synaptic transmission in the hippocampus, kainate receptors and their RNA editing might play a role in the antiseizure action of the treatment To. investigate the potential effect of the ketogenic diet on GluR(5) mRNA and GluR(5) mRNA expression and Q/R site editing, we used the kainate-induced epilepsy model in the present study. Reverse transcription polymerase chain reaction was performed to determine GluR(5) and GluR(6) mRNA expression, and RNA editing was analyzed with the Bbvl restriction enzyme assay. The results demonstrated that expression of GluR(6) mRNA, but not GluR(5) mRNA, was significantly increased after 8 weeks of dietary treatment. Neither the GluR(5) nor the GluR(6) RNA editing rate at the Q/R site was significantly changed by dietary treatment. These data indicate that GluR(6) may be involved in the anticonvulsant mechanism of ketogenic diet treatment. (C) 2008 Elsevier Inc. All rights reserved.</p