Membrane models of E. coli containing cyclic moieties in the aliphatic lipid chain

Most molecular dynamics (MD) simulations of bacterial membranes simplify the membrane by composing it of only 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) or in some cases with1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) as well. However, an important constituent of bacterial membranes are lipids with a cyclopropane ring in the acyl chain. We developed a complex membrane that reflects the diverse population of lipids within E. coli cytoplasmic membranes, including cyclic lipids. Differences between the deuterium order profile of cyclic and monounsaturated lipids are observed. Furthermore, inclusion of the ring decreases the surface density of the bilayer and produces a more rigid membrane as compared to POPE/POPG membranes. Additionally, the diverse acyl chain length creates a thinner bilayer which better matches the hydrophobic thickness of E. coli transmembrane proteins. We believe the complex membrane is more accurate and suggest the use of it in MD simulations rather than simple membranes

INTERFACIAL CONSIDERATIONS FOR DROPLET PCR LAB-ON-CHIP DEVICES

Lab-on-chip devices have the potential to decentralize the current model of diagnostics to point-of-care diagnostics. Easy to use, low cost, rapid infectious disease diagnostic tools could especially impact and improve healthcare in low resource areas. Micro-total-analytical-systems could also enable smarter medical decisions, quicker patient recoveries, and cheaper healthcare costs in fully developed settings. Significant innovations to standard technologies used today will help realize the promise of lab-on-chip devices. In this work, innovative technologies compatible with current lab-on-chip devices were investigated to simplify their operation, decrease their complexity, and reduce their cost. The interfacial aspects that dominate microfluidic systems, and in particular droplet polymerase chain reaction (PCR) devices, are emphasized. Droplet PCR utilizing microfluidic technology has largely been automated, but sample preparation methods prior to amplification remains a laborious process. We have developed particles that condense the many steps of sample preparation into a single buffer protocol. The particles were made by crosslinking chitosan, a pH responsive biopolymer. DNA was electrostatically and sterically adsorbed to the beads at pH 8.5. Furthermore, amplification of DNA directly off the beads was demonstrated eliminating the need to desorb DNA into solution. Implementation of these particles will drastically simplify droplet PCR lab-on-chip devices. We also characterized the adsorption of polymerase at the oil-water interfaces of droplets and identified a surfactant to prevent the loss of polymerase in solution. The pendant drop technique was used to observe the change in interfacial tension due to adsorption of Taq Pol and/or surfactants to the interface. PCR performance of two surfactants, Brij L4 and ABIL EM90, were predicted from equilibrium interfacial tension measurements. Brij L4, a surfactant that had never been used with PCR, prevented polymerase adsorption and enabled more efficient PCR than ABIL EM90, a popular PCR surfactant. Lastly, we ambitiously designed a system to conduct droplet PCR without oil or surfactants. Droplets were generated on-chip by adapting a co-flow droplet generating device previously developed in our group. Then droplets were immobilized on-chip in hydrodynamic traps. Two different modes of trapping were demonstrated, indirect and direct. Also, all aspects of an air continuous phase droplet PCR device were considered such as protein adsorption to channel walls and droplet evaporation during thermal cycling

Combined Bile Duct and Pancreatic Duct Injuries during Distal Gastrectomy for Obstructing Peptic Ulcer Disease

A combination of bile and pancreatic duct injuries is very rare. Anomalous ductal anatomy, distorting duodenal fibrosis, and pancreatic atrophy predispose to this untoward complication during performance of distal gastrectomy for benign peptic stricture. The technical challenges posed by this complication and experience gained by managing it are shared

Bandwidth Maximization in Multicasting

We formulate bandwidth maximization problems in multicasting streaming data. Multicasting is used to stream data to many terminals simultaneously. The goal here is to maximize the bandwidth at which the data can be transmitted satisfying the capacity constraints on the links. A typical network consists of the end-hosts which are capable of duplicating data instantaneously, and the routers which can only forward the data. We show that if one insists that all the data to a terminal should travel along a single path, then it is NP-hard to approximate the maximum bandwidth to a factor better than 2. We also present a fast 2-approximation algorithm. If dierent parts of the data to a terminal can travel along dierent paths, the problem can be approximated to the same factor as the minimum Steiner tree problem on undirected graphs. We also prove that in case of a tree network, both versions of the bandwidth maximization problem can be solved optimally in polynomial time. Of independent interest is our result that the minimum Steiner tree problem on tree-metrics can be solved in polynomial time

Ivermectin-Induced Acute Psychosis in Patients Infected With COVID-19 Pneumonia

Coronavirus disease 2019 (COVID-19) pneumonia is an infection of the lungs that causes severe inflammation in the lungs\u27 alveoli. It causes alveoli to fill with fluid, blood clots, and sometimes even pus. Patients who are infected with COVID-19 pneumonia experience severe cough, shortness of breath, fever, fatigue, chest pain, night sweats, chills, loss of appetite, etc. During the initial phase of the COVID-19 pneumonia pandemic, it was thought that ivermectin might be helpful in patients infected with COVID-19 pneumonia, but this was later proven to be false due to its severe risks/side effects. Infectious Disease Society of America (IDSA) suggests against the use of ivermectin for COVID-19 pneumonia. However, some providers continue to use ivermectin as one of the treatments for patients infected with COVID-19 infection. In this case report, we will discuss ivermectin causing acute psychosis in healthy 45- and 51-year-old patients with no known history of any mental health illness