Pretransplant C-reactive protein-to-albumin ratio predicts mortality in kidney transplant recipients: a retrospective cohort study.

Background: The C-reactive protein (CRP)-to-albumin ratio (CAR) is a more effective prognostic indicator than CRP or albumin alone in various diseases. This study aimed to evaluate the predictive value of the CAR for mortality in kidney transplant recipients (KTRs). Methods: A total of 924 patients who underwent their first kidney transplantation at Kyungpook National University Hospital during 2006-2020 were enrolled and classified into quartile (Q) groups according to their pretransplant CAR values. A Cox regression analysis was conducted to analyze the hazard ratios (HRs) of mortality. Results: Fifty-nine patients died during the posttransplant period (mean, 85.2±44.2 months). All-cause mortality (Q1, 3.0%; Q2, 4.8%; Q3, 7.8%; Q4, 10.0%; P for trend <0.001) and infection-related mortality increased linearly with an increase in CAR (P for trend=0.004). The Q3 and Q4 had higher risks of all-cause mortality than Q1 after adjusting for confounding factors (Q3 adjusted HR [aHR] 2.49, 95% confidence interval [CI] 1.04-5.99, P=0.041; Q4 aHR 3.09, 95% CI 1.31-7.27, P=0.010). Q4 was also independently associated with infection-related mortality (aHR 5.83, 95% CI 1.27-26.8, P=0.023). The area under the curve of the CAR for all-cause and infection-related mortality was higher than that of CRP or albumin alone. There was no association between CAR and death-censored graft failure or acute rejection. Conclusions: A higher pretransplant CAR increases the risk of posttransplant mortality, particularly infection-related, in KTRs. Pretransplant CAR can be an effective and easily accessible predictor of posttransplant mortality.

Virtual walls based on oil-repellent surfaces for low-surface-tension liquids.

Manipulating and controlling water-based aqueous solutions with the use of virtual walls is relatively simple compared to that of nonaqueous low-surface-tension liquids, which pose greater challenges to microfluidic devices. This letter reports a novel technique to form a virtual wall for various low-surface-tension liquids. A microfluidic channel with virtual walls has been made to guide low-surface-tension liquids by using a specially designed oil-repellent surface. Unlike generic superoleophobic surfaces, our oil-repellent surface exhibited strong repellency to the lateral flow of low-surface-tension liquids such as hexadecane and dodecane. A plasma-assisted surface micromachining process has been utilized to form the oil-repellent surface. The use of combined features of re-entrant geometries on the surface played an important role in promoting its repellence to the lateral flow of low-surface-tension liquids. We have successfully demonstrated how low-surface-tension liquids can be well confined by the virtual walls.

An electrokinetically driven micro liquid piston for leak-tight gas pumping.

This paper presents a gas pumping technique demonstrating an electrokinetically driven liquid piston, which can provide a complete sealing in a microfluidic channel by fully wetting the inner surface without leaving any void spots. The liquid piston can push or pull a gaseous medium very effectively by not allowing any backflow. Successful leak-tight gas pumping with zero dead volume has been achieved.

Femtogram mass resolution in a liquid environment using a low loss vacuum-gapped quartz crystal resonator.

The well-known dependence of Q on liquid damping effect has been significantly reduced through an acoustic energy loss isolation layer and a sensing diaphragm supported by microposts, which reduce the direct contact area at the interface between the resonator and surrounding liquid.

Chembio extraction on a chip by nanoliter droplet ejection.

This paper describes a novel liquid separation technique for chembio extraction by an ultrasonic nanoliter-liquid-droplet ejector built on a PZT sheet. This technique extracts material from an aqueous two-phase system (ATPS) in a precise amount through digital control of the number of nanoliter droplets, without any mixing between the two liquids in the ATPS. The ultrasonic droplet ejector uses an acoustic streaming effect produced by an acoustic beam focused on the liquid surface, and ejects liquid droplets only from the liquid surface without disturbing most of the liquid below the surface. This unique characteristic of the focused acoustic beam is perfect (1) for separating a top-layer liquid (from the bulk of liquid) that contains particles of interest or (2) for recovering a top-layer liquid that has different phase from a bottom-layer liquid. Three kinds of liquid extraction are demonstrated with the ultrasonic droplet ejector: (1) 16 microl of top layer in Dextran-polyethylene glycol-water ATPS (aqueous two-phase system) is recovered within 20 s; (2) micron sized particles that float on water surface are ejected out with water droplets; and (3) oil layer on top of water is separated out.