Laura Bolton

Ubiquitination of proteins provides a powerful and versatile post-translational signal in the eukaryotic cell. The formation of a thioester bond between ubiquitin (Ub) and the active site of a ubiquitin-conjugating enzyme (E2) is critical for the transfer of Ub to substrates. Assembly of a functional ubiquitin ligase (E3) complex poised for Ub transfer involves recognition and binding of an E2∼Ub conjugate. Therefore, full characterization of the structure and dynamics of E2∼Ub conjugates is required for further mechanistic understanding of Ub transfer reactions. Here we present characterization of the dynamic behavior of E2∼Ub conjugates of two human enzymes, UbcH5c∼Ub and Ubc13∼Ub, in solution as determined by nuclear magnetic resonance and small-angle X-ray scattering. Within each conjugate, Ub retains great flexibility with respect to the E2, indicative of highly dynamic species that adopt manifold orientations. The population distribution of Ub conformations is dictated by the identity of the E2: the UbcH5c∼Ub conjugate populates an array of extended conformations, and the population of Ubc13∼Ub conjugates favors a closed conformation in which the hydrophobic surface of Ub faces helix 2 of Ubc13. We propose that the varied conformations adopted by Ub represent available binding modes of the E2∼Ub species and thus provide insight into the diverse E2∼Ub protein interactome, particularly with regard to interaction with Ub ligases.

Significance: Biofilms have been implicated in a variety of wound complications. Recent Advances: Research has confirmed that biofilms form in wounds of patients experiencing delayed healing and may be a precursor to infection. Critical Issues: Research into the strength of this association is still in its infancy. Is biofilm formation a cause of these complications, a step toward them, or a signal that unresolved factors injuring tissue or delaying healing are setting the stage for biofilm formation, infection, and healing delay? To qualify biofilms for use in informing clinical practice decisions, biofilm characteristics supporting those decisions need standardized definitions and valid evidence that they predict or diagnose healing or infection outcomes. Literature searches of relevant terms reviewed biofilm definitions and validation of their role in predicting and diagnosing delayed wound healing or infection. Future Directions: Further research is needed to provide a rapid accurate technique to identify and characterize biofilms in ways that optimize their validity in diagnosing or screening patient risk of infection or delayed healing and to inform clinical decisions. This research will help validate biofilm's capacity to support wound care clinical practice decisions and establish their importance in guiding clinical practice.

Structural features of neurons create challenges for effective production and distribution of essential metabolic energy. We investigated how metabolic energy is distributed between cellular compartments in photoreceptors. In avascular retinas, aerobic production of energy occurs only in mitochondria that are located centrally within the photoreceptor. Our findings indicate that metabolic energy flows from these central mitochondria as phosphocreatine toward the photoreceptor's synaptic terminal in darkness. In light, it flows in the opposite direction as ATP toward the outer segment. Consistent with this model, inhibition of creatine kinase in avascular retinas blocks synaptic transmission without influencing outer segment activity. Our findings also reveal how vascularization of neuronal tissue can influence the strategies neurons use for energy management. In vascularized retinas, mitochondria in the synaptic terminals of photoreceptors make neurotransmission less dependent on creatine kinase. Thus, vasculature of the tissue and the intracellular distribution of mitochondria can play key roles in setting the strategy for energy distribution in neurons.

INTRODUCTION: Wound-healing outcomes applying standardized protocols have typically been measured within controlled clinical trials, not natural settings. Standardized protocols of wound care have been validated for clinical use, creating an opportunity to measure the resulting outcomes. PURPOSE: Wound-healing outcomes were explored during clinical use of standardized validated protocols of care based on patient and wound assessments. DESIGN: This was a prospective multicenter study of wound-healing outcomes management in real-world clinical practice. METHOD: Healing outcomes from March 26 to October 31, 2001, were recorded on patients in 3 long-term care facilities, 1 long-term acute care hospital, and 12 home care agencies for wounds selected by staff to receive care based on computer-generated validated wound care algorithms. After diagnosis, wound dimensions and status were assessed using a tool adapted from the Pressure Sore Status Toolfor use on all wounds. Wound, ostomy, and continence nursing professionals accessed consistent protocols of care, via telemedicine in home care or paper forms in long-term care. A physician entered assessments into a desktop computer in the wound clinic. Based on evidence that healing proceeds faster with fewer infections in environments without gauze, the protocols generally avoided gauze dressings. RESULTS: Most of the 767 wounds selected to receive the standardized-protocols of care were stage III-IV pressure ulcers (n = 373; mean healing time 62 days) or full-thickness venous ulcers (n = 124; mean healing time 57 days). Partial-thickness wounds healed faster than same-etiology full-thickness wounds. CONCLUSIONS: These results provide benchmarks for natural-setting healing outcomes and help to define and address wound care challenges. Outcomes primarily using nongauze protocols of care matched or surpassed best previously published results on similar wounds using gauze-based protocols of care, including protocols applying gauze impregnated with growth factors or other agents.