Toward a disposable low-cost LOC device: heterogeneous polymer micro valve and pump fabricated by UV/ozone-assisted thermal fusion bonding

Herein, a heterogeneous polymer micro valve and pump with a polypropylene (PP) membrane was developed in a low-cost manner via UV/ozone-assisted thermal fusion bonding. The proposed fabrication technique allowed for a geometrically selective bonding; consequently, the membrane was prevented from bonding with the valve seat of the diaphragm micro-valve, without patterning a protection layer or introducing an additional structure. The developed device withstands 480 kPa of static pressure and up to 350 kPa of a vibration pressure, providing sufficient bonding strength for microfluidic actuations. The fabricated micro valve and pump are fully characterized and compared with a poly(dimethylsiloxane) (PDMS) membrane glass device, showing comparable valving and pumping performance. As a result, the robust PP membrane micro valve and pump are simply implemented in a facile manner, and demonstrated excellent performance, which is highly desirable for mass production of disposable lab-on-a-chip (LOC) devices.

Herein, a heterogeneous polymer micro valve and pump with a polypropylene (PP) membrane was developed in a low-cost manner via UV/ozone-assisted thermal fusion bonding.     

Kidney Transplant Outcomes for Prior Living Organ Donors

The Organ Procurement and Transplantation Network gives priority in kidney allocation to prior live organ donors who require a kidney transplant. In this study, we analyzed the effect of this policy on facilitating access to transplantation for prior donors who were wait-listed for kidney transplantation in the United States. Using 1:1 propensity score–matching methods, we assembled two matched cohorts. The first cohort consisted of prior organ donors and matched nondonors who were wait-listed during the years 1996–2010. The second cohort consisted of prior organ donors and matched nondonors who underwent deceased donor kidney transplantation. During the study period, there were 385,498 listings for kidney transplantation, 252 of which were prior donors. Most prior donors required dialysis by the time of listing (64% versus 69% among matched candidates; P=0.24). Compared with matched nondonors, prior donors had a higher rate of deceased donor transplant (85% versus 33%; P<0.001) and a lower median time to transplantation (145 versus 1607 days; P<0.001). Prior donors received higher-quality allografts (median kidney donor risk index 0.67 versus 0.90 for nondonors; P<0.001) and experienced lower post-transplant mortality (hazard ratio, 0.19; 95% confidence interval, 0.08 to 0.46; P<0.001) than matched nondonors. In conclusion, these data suggest that prior organ donors experience brief waiting time for kidney transplant and receive excellent-quality kidneys, but most need pretransplant dialysis. Individuals who are considering live organ donation should be provided with this information because this allocation priority will remain in place under the new US kidney allocation system.     

Nox2 Is a Mediator of Ischemia Reperfusion Injury

Delayed graft function (DGF) results from ischemia‐reperfusion injury (IRI) and the generation of reactive oxygen species. We hypothesized that NADPH oxidase 2 (Nox2) plays an important role in pathways leading to DGF. We tested this hypothesis in vitro, in an animal model of IRI using wild type and Nox2^?/? mice, and in patients with DGF. Under hypoxic conditions, primary tubular epithelial cells from Nox2^?/? mice had reduced expression of MMP2, vimentin, and HSP27. BUN and creatinine levels were significantly increased in both Nox2^?/? and WT mice at 4 weeks and 6 months after IRI, suggesting the development of acute and chronic kidney injury. At 4 weeks, kidney fibrosis (α‐SMA, picrosirius) and oxidative stress (dihydroethidine, HNE) were significantly reduced in Nox2^?/? mice, confirming the oxidative and pro‐fibrotic effects of Nox2. The molecular signature of IRI using genomic analyses demonstrated a significant decline in hypoxia reponse, oxidative stress, fibrosis, and inflammation in Nox2^?/? mice. Immunohistochemical analyses of pre‐implanatation kidney allograft biopsies from patients with subsequent DGF showed significantly greater Nox2 levels and vascular injury compared with patients without DGF. These studies demonstrate that Nox2 is a modulator of IRI and its absence is associated with reduced inflammation, OS, and fibrosis.