Cell-free DNA fetal fraction in twin gestations in single-nucleotide polymorphism-based noninvasive prenatal screening

Objectives

The performance of noninvasive prenatal screening (NIPS) for fetal aneuploidy in twin pregnancies is dependent on the amount of placentally derived cell-free DNA, the “fetal fraction (FF),” present in maternal plasma. We report FF values in monozygotic (MZ) and dizygotic (DZ) pregnancies.

Methods

We reviewed FF in pregnancies at 10 to 20 completed weeks gestational age based on single-nucleotide polymorphism (SNP)-based NIPS where zygosity was routinely established in twin pregnancies. The cohort included 121 446 (96.3%) singleton, 1454 (1.2%) MZ, and 3161 (2.5%) DZ pregnancies. For DZ twins, individual FFs were measured.

Results

Combined FF for DZ and MZ fetuses were 35% and 26% greater than singletons, respectively. The individual FF contributions from each fetus in DZ twins were, on average, 32% less than singletons. FF in DZ twin pairs were moderately correlated (Pearson correlation coefficient.66). When a threshold of 2.8% FF was applied to define uninterpretable results, 1.7% (2102/121 446) of singletons, 0.8% (11/1454) of MZ pairs, and 5.6% (178/3161) of DZ pairs were uninterpretable.

Conclusion

For optimal aneuploidy NIPS in twin pregnancies, zygosity should be established and in DZ twins FF for both fetuses should be determined to identify those cases where results can be reliably interpreted.     

Dioxion-/Furan-’Verbrennungsprofile’ aus Hochtemperaturprozessen

Present knowledge assumes that different mechanisms acting downstream in high temperature processes lead to the formation of polychlorinated dibenzo(p)dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Concerning the 17 2,3,7,8-Cl-substituted PCDD/F congeners in particular, there is new evidence for a single-step reaction type (recently reported in this publication series, of. also parts 1 and 2). A formation based on a combination of the several mechanisms, which have been proposed and discussed since 1985, becomes more and more unlikely. Qualitatively the PCDD/F formation downstream from high temperature processes depends rather on a thermodynamically forced single reaction step, and on pure statistical distribution quantitatively. This may be a new ‘Thermostat Synthesis’ instead of ‘de novo’.     

The NICE-Whyco technologies partnership: saving energy, dollars, and the environment in the metal plating industry

In partnership with the US Department of Energy’s Office of Industrial Technology, Whyco Technologies, Inc., has developed an innovative perforated plating barrel used in the plating of metal parts. This new technology employs a thin-walled construction, differing from the traditional thick-wall design required to provide adequate structural integrity. The thicker walls lowered the efficiency of transferring plating solution into and out of the barrel and diminished the electrical current pushed through the holes and onto the parts being plated. By machining pockets out of the traditional thick-walled perforated structure, Whyco produced a ‘honeycomb’ of staggered cells, allowing for the greatest number of holes per open area while maintaining structural integrity. Hydrodynamic pumping occurs during barrel rotation to create greater solution transfer than in traditional barrels. The Whyco barrel has higher current density plating, which leads to faster plating cycles, reduced bath concentration, and better plating of difficult chemistries such as in alloys. This new technology has helped the company reduce energy use by 16%, eliminate more than 480 tons/year of solid waste, and reduce wastewater by more than 17 000 gallons/day. The resulting cost savings total more than $500 000 annually. The company has manufactured and sold more than 275 of these barrels to other electroplating companies that are reporting up to a 40% increase in plating productivity and similar energy and environmental impacts.     

Predicting System-Scale Impacts of Oyster Clearance on Phytoplankton Productivity in a Small Subtropical Estuary

Oyster populations in south Florida estuaries have declined in part through altered salinity driven by anthropogenic changes in freshwater inputs. In particular, the St. Lucie Estuary (SLE) in southeastern Florida has suffered widespread loss of oyster habitat. With efforts underway to improve water quality and oyster habitat in the SLE, the goal of this study was to develop a model to assess ecosystem level impacts of oyster restoration. Phytoplankton and oyster biomass modeling targets were established from observational data collected from 2005 to 2009. Modeled oyster biomass production and filtration fluctuated with temperature, salinity, and total suspended solids from a combination of observational and predicted input functions in 10-year simulations (1998–2007). Model estimates of oyster biomass fluctuated with salinity from near zero after extreme freshwater discharge in 2002–2003 and 2004–2005 to maximum values near 150.0 and 200.0 g?C?m^?2 in spring 1999 and fall 2006. There was potential for algal blooms as turnover time for the phytoplankton standing stock (15.6 days) was faster than water mass turnover (21.0 days). While >1,000 days were required for 50 ha of oyster habitat to filter the entire volume of the estuarine segment, filter time reduced to <20 days with an estimated fivefold increase in net consumption of phytoplankton if the oyster habitat was increased to 300 ha. Re-establishment of biologically desirable salinity envelopes would stabilize oyster survival allowing the possibility for successful habitat restoration to benefit water quality and faunal attributes of the St. Lucie Estuary.