Development of a Method for Clinical Evaluation of Artificial Intelligence-Based Digital Wound Assessment Tools.

Importance: Accurate assessment of wound area and percentage of granulation tissue (PGT) are important for optimizing wound care and healing outcomes. Artificial intelligence (AI)-based wound assessment tools have the potential to improve the accuracy and consistency of wound area and PGT measurement, while improving efficiency of wound care workflows. Objective: To develop a quantitative and qualitative method to evaluate AI-based wound assessment tools compared with expert human assessments. Design, Setting, and Participants: This diagnostic study was performed across 2 independent wound centers using deidentified wound photographs collected for routine care (site 1, 110 photographs taken between May 1 and 31, 2018; site 2, 89 photographs taken between January 1 and December 31, 2019). Digital wound photographs of patients were selected chronologically from the electronic medical records from the general population of patients visiting the wound centers. For inclusion in the study, the complete wound edge and a ruler were required to be visible; circumferential ulcers were specifically excluded. Four wound specialists (2 per site) and an AI-based wound assessment service independently traced wound area and granulation tissue. Main Outcomes and Measures: The quantitative performance of AI tracings was evaluated by statistically comparing error measure distributions between test AI traces and reference human traces (AI vs human) with error distributions between independent traces by 2 humans (human vs human). Quantitative outcomes included statistically significant differences in error measures of false-negative area (FNA), false-positive area (FPA), and absolute relative error (ARE) between AI vs human and human vs human comparisons of wound area and granulation tissue tracings. Six masked attending physician reviewers (3 per site) viewed randomized area tracings for AI and human annotators and qualitatively assessed them. Qualitative outcomes included statistically significant difference in the absolute difference between AI-based PGT measurements and mean reviewer visual PGT estimates compared with PGT estimate variability measures (ie, range, standard deviation) across reviewers. Results: A total of 199 photographs were selected for the study across both sites; mean (SD) patient age was 64 (18) years (range, 17-95 years) and 127 (63.8%) were women. The comparisons of AI vs human with human vs human for FPA and ARE were not statistically significant. AI vs human FNA was slightly elevated compared with human vs human FNA (median [IQR], 7.7% [2.7%-21.2%] vs 5.7% [1.6%-14.9%]; P < .001), indicating that AI traces tended to slightly underestimate the human reference wound boundaries compared with human test traces. Two of 6 reviewers had a statistically higher frequency in agreement that human tracings met the standard area definition, but overall agreement was moderate (352 yes responses of 583 total responses [60.4%] for AI and 793 yes responses of 1166 total responses [68.0%] for human tracings). AI PGT measurements fell in the typical range of variation in interreviewer visual PGT estimates; however, visual PGT estimates varied considerably (mean range, 34.8%; mean SD, 19.6%). Conclusions and Relevance: This study provides a framework for evaluating AI-based digital wound assessment tools that can be extended to automated measurements of other wound features or adapted to evaluate other AI-based digital image diagnostic tools. As AI-based wound assessment tools become more common across wound care settings, it will be important to rigorously validate their performance in helping clinicians obtain accurate wound assessments to guide clinical care.

Regenerative Wound Surgery: Practical Application of Regenerative Medicine in the OR.

Chronic nonhealing wounds cause significant morbidity and mortality and remain a challenging condition to treat. Regenerative wound surgery involves operative debridement of wounds to remove dead and healing-impaired tissue and bacterial contamination and, subsequently, the application of regenerative medicine treatments to accelerate healing. Regenerative treatments aim to restore native tissue structure and function by targeting biological mechanisms underlying impaired healing. A wide range of regenerative modalities are used for treating chronic and complex wounds, including decellularized scaffolds, living engineered donor tissues, autologous stem cells, and recombinant growth factors. Each of these modalities has specific and sometimes complex requirements for implementation. The advanced wound care team, including OR staff members, should be aware of how these products are used and regulated. This article highlights some of the common and emerging regenerative treatments that are applied in wound surgery and focuses on how the products are used practically in the OR.

A Framework to Assist Providers in the Management of Patients with Chronic, Nonhealing Wounds.

GENERAL PURPOSE: To describe the development of an evidence-based wound electronic medical record (WEMR) framework for providers to execute timely, protocol-based, best-practice care for patients with chronic, nonhealing wounds. TARGET AUDIENCE: This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care. LEARNING OBJECTIVES/OUTCOMES: After completing this continuing education activity, you should be better able to: ABSTRACT: The care of patients with nonhealing wounds involves a host of treatment modalities. The authors developed a wound-specific framework to enhance provider management of these wounds and a summary sheet to involve patients and caregivers in their own healthcare to improve treatment adherence and outcomes. Implementing evidence-based practice for chronic wounds enables corrective actions to optimize care.

A Wolf in Sheep's Clothing: An Unusual Presentation of Diabetic Myonecrosis.

GENERAL PURPOSE: To provide information about the diagnosis and treatment of diabetic myonecrosis (DMN).This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care.After participating in this educational activity, the participant should be better able to:1. Cite the incidence and symptomatology of diabetic myonecrosis.2. Identify the diagnostic tests associated with DMN.3. Summarize the evidence-based treatments for DMN.Diabetic myonecrosis is a rare complication of poorly controlled diabetes mellitus that presents similarly to many common conditions such as cellulitis, abscess, and fasciitis. Therefore, a high index of suspicion is required for diagnosis. Magnetic resonance imaging is the investigative test of choice. Treatment includes antiplatelet therapy, nonsteroidal anti-inflammatory agents, and glycemic control.

Wound Care Center of Excellence: A Process for Continuous Monitoring and Improvement of Wound Care Quality.

GENERAL PURPOSE: To provide information about a study using a new process for continuous monitoring to improve chronic wound care quality.This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care.After completing this continuing education activity, you should be better able to:1. Recognize problems associated with chronic wound care.2. Identify methods used in this project to improve care.3. Illustrate the findings from this and similar projects and implications for providing improved wound care.Patients with chronic wounds require complex care because of comorbidities that can affect healing. Therefore, the goal of this project was to develop a system of reviewing all hospitalized patients seen by the study authors' wound care service on a weekly basis to decrease readmissions, morbidity, and mortality. Weekly multidisciplinary conferences were conducted to evaluate patient data and systematically assess for adherence to wound care protocols, as well as to create and modify patient care plans. This review of pathology and the performance of root-cause analyses often led to improved patient care.

A Perioperative Approach to Increase Limb Salvage When Treating Foot Ulcers in Patients With Diabetes.

Foot ulceration in patients with diabetes increases the risk of lower extremity amputation. Major amputations produce substantial adverse consequences, increase length of hospital stay, diminish quality of life, and increase mortality. In this article, we describe approaches that decrease amputations and improve the quality of life for patients with diabetes and foot ulcers. We highlight the role of the perioperative nurse, who is essential to providing optimal patient care in the perioperative period. Perioperative care of patients with diabetes involves providing optimal surveillance for a break in the skin of the foot, screening for neuropathy, following guidelines for foot ulcer infections, preparing for pathophysiology-based debridement, using adjuvant therapies, and offloading the patient's affected foot. Nurses should understand the disease process and pathophysiology and how to use these approaches in the perioperative setting to assist in curtailing the morbidity and mortality associated with foot ulcers in patients with diabetes.

The Future of Data-Driven Wound Care.

Care for patients with chronic wounds can be complex, and the chances of poor outcomes are high if wound care is not optimized through evidence-based protocols. Tracking and managing every variable and comorbidity in patients with wounds is difficult despite the increasing use of wound-specific electronic medical records. Harnessing the power of big data analytics to help nurses and physicians provide optimized care based on the care provided to millions of patients can result in better outcomes. Numerous applications of machine learning toward workflow improvements, inpatient monitoring, outpatient communication, and hospital operations can improve overall efficiency and efficacy of care delivery in and out of the hospital, while reducing adverse events and complications. This article provides an overview of the application of big data analytics and machine learning in health care, highlights important recent advances, and discusses how these technologies may revolutionize advanced wound care.

Revisiting old friends: Developments in understanding Histoplasma capsulatum pathogenesis.

Histoplasma capsulatum is a dimorphic pathogenic fungus and causative agent of histoplasmosis, which is a respiratory and systemic infection that is particularly severe in immunocompromised hosts and represents the fungal homolog of tuberculosis. In highly endemic regions, the majority of individuals have been infected and carry the organism in a persistent latent form that is a danger for reactivation if host defenses are suppressed. H. capsulatum has been a model organism for intracellular pathogenesis and fungal morphogenesis for decades. New genomic information and application of approaches for molecular genetic manipulation are shedding new light on virulence mechanisms.

Histoplasma capsulatum encodes a dipeptidyl peptidase active against the mammalian immunoregulatory peptide, substance P.

The pathogenic fungus Histoplasma capsulatum secretes dipeptidyl peptidase (Dpp) IV enzyme activity and has two putative DPPIV homologs (HcDPPIVA and HcDPPIVB). We previously showed that HcDPPIVB is the gene responsible for the majority of secreted DppIV activity in H. capsulatum culture supernatant, while we could not detect any functional contribution from HcDPPIVA. In order to determine whether HcDPPIVA encodes a functional DppIV enzyme, we expressed HcDPPIVA in Pichia pastoris and purified the recombinant protein. The recombinant enzyme cleaved synthetic DppIV substrates and had similar biochemical properties to other described DppIV enzymes, with temperature and pH optima of 42 degrees C and 8, respectively. Recombinant HcDppIVA cleaved the host immunoregulatory peptide substance P, indicating the enzyme has the potential to affect the immune response during infection. Expression of HcDPPIVA under heterologous regulatory sequences in H. capsulatum resulted in increased secreted DppIV activity, indicating that the encoded protein can be expressed and secreted by its native organism. However, HcDPPIVA was not required for virulence in a murine model of histoplasmosis. This work reports a fungal enzyme that can function to cleave the immunomodulatory host peptide substance P.

Secreted dipeptidyl peptidase IV activity in the dimorphic fungal pathogen Histoplasma capsulatum.

Dipeptidyl peptidase type IV (DppIV) enzymes are broadly distributed phylogenetically and display diverse functions, including intercellular signaling, immunomodulation, protein maturation and processing, metabolism, and nutrient acquisition. We identified a secreted proteolytic activity in Histoplasma capsulatum effective toward DppIV-specific substrates. In order to determine the gene(s) that encodes this activity, we identified two putative DPPIV homologs (HcDPPIVA and HcDPPIVB) in H. capsulatum based on a homology search with Aspergillus fumigatus DppIV. Comparative sequence analysis revealed that HcDppIVA is similar to secreted DppIV enzymes, while HcDppIVB clusters with intracellular DapB-like enzymes. Unexpectedly, silencing of HcDPPIVA by RNA interference (RNAi) had no effect on secreted DppIV activity and an HcDPPIVA-null deletion mutant also showed no abrogation of secreted DppIV activity. In contrast, RNAi silencing of HcDPPIVB significantly reduced the level of secreted DppIV activity. RNAi silencing of HcDPPIVB in the HcDPPIVA-null mutant had no additional effect on secreted DppIV activity, indicating that HcDPPIVA does not contribute to secreted activity. RNAi silencing of HcDPPIVB did not affect the ability to kill a murine macrophage-like cell line, RAW 264.7, indicating that this gene is not required for infection of macrophages.

Histoplasma capsulatum secreted gamma-glutamyltransferase reduces iron by generating an efficient ferric reductant.

The intracellular fungal pathogen Histoplasma capsulatum (Hc) resides in mammalian macrophages and causes respiratory and systemic disease. Iron limitation is an important host antimicrobial defence, and iron acquisition is critical for microbial pathogenesis. Hc displays several iron acquisition mechanisms, including secreted glutathione-dependent ferric reductase activity (GSH-FeR). We purified this enzyme from culture supernatant and identified a novel extracellular iron reduction strategy involving gamma-glutamyltransferase (Ggt1) activity. The 320 kDa complex was composed of glycosylated protein subunits of about 50 and 37 kDa. The purified enzyme exhibited gamma-glutamyl transfer activity as well as iron reduction activity in the presence of glutathione. We cloned and manipulated expression of the encoding gene. Overexpression or RNAi silencing affected both GGT and GSH-FeR activities concurrently. Enzyme inhibition experiments showed that the activity is complex and involves two reactions. First, Ggt1 initiates enzymatic breakdown of GSH by cleavage of the gamma-glutamyl bond and release of cysteinylglycine. Second, the thiol group of the released dipeptide reduces ferric to ferrous iron. A combination of kinetic properties of both reactions resulted in efficient iron reduction over a broad pH range. Our findings provide novel insight into Hc iron acquisition strategies and reveal a unique aspect of Ggt1 function in this dimorphic mycopathogen.

Histoplasma capsulatum yeast phase-specific protein Yps3p induces Toll-like receptor 2 signaling.

Histoplasma capsulatum is a common cause of fungal infection in certain geographic areas, and although most infections are asymptomatic, it is capable of causing histoplasmosis, a disseminated, life-threatening disease, especially in immunocompromised individuals. A deeper understanding of this host-pathogen interaction is needed to develop novel therapeutic strategies to counter lethal infection. Although several lines of evidence suggest that this fungus is neurotropic in HIV patients, little is known about the immunobiology of Histoplasma infection in the central nervous system [CNS]. The goal of the present study was to understand the innate neuroimmune mechanisms that recognize H. capsulatum during the initial stages of infection. Using a 293T stable cell line expressing murine Toll-like receptor 2 [TLR2], we show here that TLR2 recognizes H. capsulatum cell wall protein Yps3p and induces the activation of NF-kappaB. In further experiments, we tested the ability of Yps3p to induce signaling from TLR2 in primary microglial cells, the resident brain macrophages of the CNS. Our data show that H. capsulatum Yps3p induced TLR2 signaling in wild-type microglia, but not in microglia isolated from TLR2 KO mice, confirming that Yps3p is a ligand for TLR2. Furthermore, Yps3p-induced TLR2 signaling was suppressed by vaccinia virus-encoded TLR inhibitors. This is the first demonstration of a fungal protein serving as a TLR ligand and mediating signaling in primary brain cells.

Ferrous, but not ferric, iron maintains homeostasis in Histoplasma capsulatum triacylglycerides.

Iron is an indispensable micronutrient for virtually all microorganisms, where it acts as a cofactor of many enzymes involved in regulation of multiple cellular and physiological functions. This metal is also considered an important determinant contributing to the pathogenesis of fungal infectious diseases, and therefore the identification of iron-regulated metabolic processes occurring within the invading fungal cell can help the development of new antifungal therapeutic strategies. In this study, we examined relationships between iron availability and neutral storage lipids in Histoplasma capsulatum, a dimorphic fungus responsible for the most common respiratory and systemic mycosis in humans. Yeast cells were grown in a defined minimal medium supplemented with or without iron. Lipids were extracted from cells at the log and late stationary growth phases, then separated by thin-layer chromatography, and fatty acids were analyzed by gas chromatography. A culture age-related decrease in the unsaturated fatty acid content was observed in all four neutral lipid classes examined. Iron-related alterations could be seen in relation to triacylglycerol and free fatty acid pools, whereas no iron-dependent effects were detected in diacylglycerol and steryl ester fractions. Regarding triacylglycerols, the presence of iron positively affected the content of unsaturated fatty acids, and this stabilizing action of iron was notably increased when ferrous ions were added. Subsequent iron uptake studies showed a definite preference of H. capsulatum to acquire iron in its reduced, more soluble, ferrous form, and therefore, the availability of iron may be the underlying reason for the observed iron-maintained homeostasis in H. capsulatum triacylglycerols.

Neutral storage lipids of Histoplasma capsulatum: effect of culture age.

Lipids contribute significantly to the pathogenesis of fungal infectious diseases and an understanding of lipid metabolism occurring in fungal pathogens can help the development of more efficient antifungal therapeutic strategies. In this study, the effect of culture age on the distribution of fatty acids among different neutral lipid (NL) classes in the dimorphic fungus Histoplasma capsulatum was investigated. Yeast cells of the G217B strain grown in two different media were collected after 4 and 7 days of growth, which roughly correspond to log and stationary culture growth phases, respectively. Neither culture age nor medium type had any influence on qualitative fatty acid (FA) profiles; however, the FA percentage composition varied with culture growth. A culture age-related decrease in the content of unsaturated FAs could be observed in all four of the NL classes examined, but the most intensive changes were detected in diacylglycerol and free FA fractions. Conversely, an increase in saturated FAs was observed. The transcriptional analysis of two major delta 9- and delta 12-FA desaturase genes, ode1 and sde1, showed no differences in their expression levels under experimental conditions. These results showing the dynamics of changes in FA composition in the NL fraction were concomitant with nutrient exhaustion in aging H. capsulatum cultures. Overall, the results presented in this work not only have implications for our knowledge of basic lipid biochemistry of H. capsulatum, but also will contribute to better understanding of biology and pathogenesis of this fungus and, consequently, can help in the discovery of more effective antifungal drugs.

Production of extracellular proteolytic activity by Histoplasma capsulatum grown in Histoplasma-macrophage medium is limited to restriction fragment length polymorphism class 1 isolates.

Extracellular proteolytic activity was studied for 28 strains of Histoplasma capsulatum var. capsulatum and 2 strains of H. capsulatum var. duboisii. Secreted protease activity assessed by skim milk agarose clearance was limited solely to H. capsulatum var. capsulatum restriction fragment length polymorphism (RFLP) class 1 strains. There was a difference in proteolytic activity levels among class 1 strains. Extracellular proteolytic activity was further determined during growth of those strains in liquid medium using azodye-impregnated protein substrates. In general, the highest activities were measured when azocollagen was used, whereas azocasein and azoalbumin were cleaved less efficiently. The activity was inhibited by phenylmethylsulfonyl fluoride, 4-(2-aminoethyl) benzenesulfonyl fluoride, antipain, and chymostatin, indicating, thereby, the presence of chymotrypsin-like serine proteases. Chromatographic analyses as well as variable substrate use at different culture times revealed production of at least 2 different enzyme pools of the same serine-like protease family. Our results demonstrate a distinctive ability of RFLP class 1 isolates to produce and secrete serine proteinase-type activity. This peculiarity may be relevant to the biology and pathogenesis of this particular clade of H. capsulatum isolates. Overall, the feature of extracellular proteolytic activity production enables a convenient and unequivocal identification of RFLP class 1 isolates and, thereby, can be used in H. capsulatum strain differentiation and typing.

Typing of Histoplasma capsulatum strains by fatty acid profile analysis.

The performance of fatty acid profiling for strain differentiation of Histoplasma capsulatum was assessed. Total fatty acids were isolated from the yeast-phase cells of seven stock and two previously unreported clinical strains of H. capsulatum var. capsulatum, as well as from one unreported clinical strain and one stock strain of H. capsulatum var. duboisii, and one strain of each of three other dimorphic zoopathogenic fungal species, Blastomyces dermatitidis, Paracoccidioides brasiliensis and Sporothrix schenckii. Different colony morphology and pigmentation types of the H. capsulatum strains were also included. The most frequently occurring fatty acids were oleic, palmitic, stearic and linoleic acids. There were variations in the relative percentage fatty acid contents of H. capsulatum strains that could be used for strain identification and discrimination. Differentiation between H. capsulatum strains was achieved by the comparison of detected fatty acids accompanied by principal component analysis using calculated Varimax-rotated principal component loadings. Statistical analysis yielded three major principal components that explained over 94 % of total variance in the data. All the strains of H. capsulatum var. capsulatum RFLP classes II and III were grouped into two distinct clusters: the heterogenic RFLP class I formed a large, but also well-defined group, whereas the outgroup strains of H. capsulatum var. duboisii, B. dermatitidis, P. brasiliensis and S. schenckii were shifted away. These data suggest that fatty acid profiling can be used in H. capsulatum strain classification and epidemiological studies that require strain differentiation at the intraspecies level.