WHS Guidelines for the Treatment of Pressure Ulcers: 2023 Update

The major populations at risk for developing pressure ulcers are older adults who have multiple risk factors that increase their vulnerability, people who are critically ill and those with spinal cord injury/disease. The reported prevalence of pressure ulcers in the United States is 2.5 million. However, this estimate is derived from acute care facilities and does not include people who are living at home or in nursing facilities. Despite the implementation of hospital and facility-based preventive measures, the incidence of pressure ulcers has not decreased in decades. In addition to the burden of pain, infection and death, it is estimated that hospital-acquired pressure ulcers cost the health system $26.8 billion annually with over 50% of the cost attributed to treating Stage 3 and 4 pressure injuries. Thus, it is critical to examine the literature and develop guidelines that will improve the outcomes of this complex and costly condition. This guideline update is a compendium of the best available evidence for the treatment of Pressure Ulcers published since the last update in 2015 and includes a new section based on changing demographics entitled ‘Palliative wound care for seriously ill patients with pressure ulcers’. The overall goal of the Wound Healing Society Guideline project is to present clear, concise and commercial free guidelines that clinicians can use to guide care, that researchers can use to develop studies that will improve treatment and that both clinicians and researchers can use to understand the gaps in our knowledge base

Limited release of previously-frozen C and increased new peat formation after thaw in permafrost peatlands

Permafrost stores globally significant amounts of carbon (C) which may start to decompose and be released to the atmosphere in form of carbon dioxide (CO 2 ) and methane (CH 4 ) as global warming promotes extensive thaw. This permafrost carbon feedback to climate is currently considered to be the most important carbon-cycle feedback missing from climate models. Predicting the magnitude of the feedback requires a better understanding of how differences in environmental conditions post-thaw, particularly hydrological conditions, control the rate at which C is released to the atmosphere. In the sporadic and discontinuous permafrost regions of north-west Canada, we measured the rates and sources of C released from relatively undisturbed ecosystems, and compared these with forests experiencing thaw following wildfire (well-drained, oxic conditions) and collapsing peat plateau sites (water-logged, anoxic conditions). Using radiocarbon analyses, we detected substantial contributions of deep soil layers and/or previously-frozen sources in our well-drained sites. In contrast, no loss of previously-frozen C as CO 2 was detected on average from collapsed peat plateaus regardless of time since thaw and despite the much larger stores of available C that were exposed. Furthermore, greater rates of new peat formation resulted in these soils becoming stronger C sinks and this greater rate of uptake appeared to compensate for a large proportion of the increase in CH 4 emissions from the collapse wetlands. We conclude that in the ecosystems we studied, changes in soil moisture and oxygen availability may be even more important than previously predicted in determining the effect of permafrost thaw on ecosystem C balance and, thus, it is essential to monitor, and simulate accurately, regional changes in surface wetness

An Arabidopsis Mutant with High Cyclic Electron Flow around Photosystem I (hcef) Involving the NADPH Dehydrogenase Complex[W][OA]

Analysis of a mutant, hcef1 , in chloroplast fructose-1,6-bisphosphatase demonstrates that C 3 plants are capable of high steady state fluxes of cyclic electron flow around photosystem I, which is important for chloroplast energy balance and involves the NAD(P)H dehydrogenase, but not the PGR5, pathway. Cyclic electron flow (CEFI) has been proposed to balance the chloroplast energy budget, but the pathway, mechanism, and physiological role remain unclear. We isolated a new class of mutant in Arabidopsis thaliana , hcef for high CEF1, which shows constitutively elevated CEF1. The first of these, hcef1 , was mapped to chloroplast fructose-1,6-bisphosphatase. Crossing hcef1 with pgr5 , which is deficient in the antimycin A–sensitive pathway for plastoquinone reduction, resulted in a double mutant that maintained the high CEF1 phenotype, implying that the PGR5-dependent pathway is not involved. By contrast, crossing hcef1 with crr2-2 , deficient in thylakoid NADPH dehydrogenase (NDH) complex, results in a double mutant that is highly light sensitive and lacks elevated CEF1, suggesting that NDH plays a direct role in catalyzing or regulating CEF1. Additionally, the NdhI component of the NDH complex was highly expressed in hcef1 , whereas other photosynthetic complexes, as well as PGR5, decreased. We propose that (1) NDH is specifically upregulated in hcef1 , allowing for increased CEF1; (2) the hcef1 mutation imposes an elevated ATP demand that may trigger CEF1; and (3) alternative mechanisms for augmenting ATP cannot compensate for the loss of CEF1 through NDH

Defects in the Expression of Chloroplast Proteins Leads to H2O2 Accumulation and Activation of Cyclic Electron Flow around Photosystem I

We describe a new member of the class of mutants in Arabidopsis exhibiting high rates of cyclic electron flow around photosystem I (CEF), a light-driven process that produces ATP but not NADPH. High cyclic electron flow 2 ( hcef2 ) shows strongly increased CEF activity through the NADPH dehydrogenase complex (NDH), accompanied by increases in thylakoid proton motive force ( pmf ), activation of the photoprotective q E response, and the accumulation of H 2 O 2 . Surprisingly, hcef2 was mapped to a non-sense mutation in the TADA1 (tRNA adenosine deaminase arginine) locus, coding for a plastid targeted tRNA editing enzyme required for efficient codon recognition. Comparison of protein content from representative thylakoid complexes, the cytochrome bf complex, and the ATP synthase, suggests that inefficient translation of hcef2 leads to compromised complex assembly or stability leading to alterations in stoichiometries of major thylakoid complexes as well as their constituent subunits. Altered subunit stoichiometries for photosystem I, ratios and properties of cytochrome bf hemes, and the decay kinetics of the flash-induced thylakoid electric field suggest that these defect lead to accumulation of H 2 O 2 in hcef2 , which we have previously shown leads to activation of NDH-related CEF. We observed similar increases in CEF, as well as increases in H 2 O 2 accumulation, in other translation defective mutants. This suggests that loss of coordination in plastid protein levels lead to imbalances in photosynthetic energy balance that leads to an increase in CEF. These results taken together with a large body of previous observations, support a general model in which processes that lead to imbalances in chloroplast energetics result in the production of H 2 O 2 , which in turn activates CEF. This activation could be from either H 2 O 2 acting as a redox signal, or by a secondary effect from H 2 O 2 inducing a deficit in ATP