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"Porter, Craig"
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The metabolic stress response to burn trauma: current understanding and therapies
by
Finnerty, Celeste C
,
Tompkins, Ronald G
,
Porter, Craig
in
Burn treatment
,
Burns
,
Burns - metabolism
2016
Major burns provoke a profound stress response, which is unrivalled in terms of its magnitude and duration. Evidence suggests that the pathophysiological stress response to severe burn trauma persists for several years after injury. Thus, there is a pressing need for novel strategies that mitigate this response and restore normal metabolic function in patients with burns. This is the first in a Series of three papers about the care of people with burns. In this paper, we review the current knowledge of the stress response to burn trauma, with a focus on hypermetabolism, muscle wasting, and stress-induced diabetes. We highlight recent developments and important knowledge gaps that need to be pursued to develop novel therapeutic strategies to improve outcomes in burn survivors.
Journal Article
Accuracy and limitation of plaque detection by coronary CTA: a section-to-section comparison with optical coherence tomography
2023
Plaques identified by Coronary CT angiography (CCTA) are important in clinical diagnosis and primary prevention. High-risk plaque features by CCTA have been extensively validated using optical coherence tomography (OCT). However, since their general diagnostic performance and limitations have not been fully investigated, we sought to compare CCTA with OCT among consecutive vessel sections. We retrospectively compared 188 consecutive plaques and 84 normal sections in 41 vessels from 40 consecutive patients referred for chest pain evaluation who had both CCTA and OCT with a median time lapse of 1 day. The distance to reference points were used to co-register between the modalities and the diagnostic performance of CCTA was evaluated against OCT. Plaque categories evaluated by CT were calcified, non-calcified and mixed. The diagnostic performance of CCTA was excellent for detecting any plaque identified by OCT with the sensitivity, specificity, negative and positive predictive values and accuracy of 92%, 98%, 99%, 84% and 93%, respectively. The lower than expected negative predictive value was due to failure of detecting sub-millimeter calcified (≤ 0.25 mm
2
) (N = 12) and non-calcified plaques (N = 4). Misclassification of plaque type accounted for majority of false negative findings (25/41, 61%) which was most prevalent among the mixed plaque (19/41, 46%). There was calcification within mixed plaques (N = 5) seen by CCTA but missed by OCT. Our findings suggest that CCTA is excellent at identifying coronary plaques except those sub-millimeter in size which likely represent very early atherosclerosis, although the clinical implication of very mild atherosclerosis is yet to be determined.
Journal Article
Time-Dependent and Organ-Specific Changes in Mitochondrial Function, Mitochondrial DNA Integrity, Oxidative Stress and Mononuclear Cell Infiltration in a Mouse Model of Burn Injury
by
Herndon, David N.
,
Oláh, Gabor
,
Brunyánszki, Attila
in
Adenosine diphosphate
,
Anesthesiology
,
Animals
2015
Severe thermal injury induces a pathophysiological response that affects most of the organs within the body; liver, heart, lung, skeletal muscle among others, with inflammation and hyper-metabolism as a hallmark of the post-burn damage. Oxidative stress has been implicated as a key component in development of inflammatory and metabolic responses induced by burn. The goal of the current study was to evaluate several critical mitochondrial functions in a mouse model of severe burn injury. Mitochondrial bioenergetics, measured by Extracellular Flux Analyzer, showed a time dependent, post-burn decrease in basal respiration and ATP-turnover but enhanced maximal respiratory capacity in mitochondria isolated from the liver and lung of animals subjected to burn injury. Moreover, we detected a tissue-specific degree of DNA damage, particularly of the mitochondrial DNA, with the most profound effect detected in lungs and hearts of mice subjected to burn injury. Increased mitochondrial biogenesis in lung tissue in response to burn injury was also observed. Burn injury also induced time dependent increases in oxidative stress (measured by amount of malondialdehyde) and neutrophil infiltration (measured by myeloperoxidase activity), particularly in lung and heart. Tissue mononuclear cell infiltration was also confirmed by immunohistochemistry. The amount of poly(ADP-ribose) polymers decreased in the liver, but increased in the heart in later time points after burn. All of these biochemical changes were also associated with histological alterations in all three organs studied. Finally, we detected a significant increase in mitochondrial DNA fragments circulating in the blood immediately post-burn. There was no evidence of systemic bacteremia, or the presence of bacterial DNA fragments at any time after burn injury. The majority of the measured parameters demonstrated a sustained elevation even at 20-40 days post injury suggesting a long-lasting effect of thermal injury on organ function. The current data show that there are marked time-dependent and tissue-specific alterations in mitochondrial function induced by thermal injury, and suggest that mitochondria-specific damage is one of the earliest responses to burn injury. Mitochondria may be potential therapeutic targets in the future experimental therapy of burns.
Journal Article
Inducible Loss of the Aryl Hydrocarbon Receptor Activates Perigonadal White Fat Respiration and Brown Fat Thermogenesis via Fibroblast Growth Factor 21
by
Carter, Dwayne
,
Denner, Larry
,
Elferink, Cornelis J.
in
Adipocytes
,
Adipose Tissue, Brown - metabolism
,
Adipose Tissue, White - drug effects
2019
The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor highly expressed in hepatocytes. Researchers have employed global and liver-specific conditional Ahr knockout mouse models to characterize the physiological roles of the AHR; however, the gestational timing of AHR loss in these models can complicate efforts to distinguish the direct and indirect effects of post-gestational AHR deficiency. Utilizing a novel tamoxifen-inducible AHR knockout mouse model, we analyzed the effects of hepatocyte-targeted AHR loss in adult mice. The data demonstrate that AHR deficiency significantly reduces weight gain and adiposity, and increases multilocular lipid droplet formation within perigonadal white adipose tissue (gWAT). Protein and mRNA expression of fibroblast growth factor 21 (FGF21), an important hepatokine that activates thermogenesis in brown adipose tissue (BAT) and gWAT, significantly increases upon AHR loss and correlates with a significant increase of BAT and gWAT respiratory capacity. Confirming the role of FGF21 in mediating these effects, this phenotype is reversed in mice concomitantly lacking AHR and FGF21 expression. Chromatin immunoprecipitation analyses suggest that the AHR may constitutively suppress Fgf21 transcription through binding to a newly identified xenobiotic response element within the Fgf21 promoter. The data demonstrate an important AHR-FGF21 regulatory axis that influences adipose biology and may represent a “druggable” therapeutic target for obesity and its related metabolic disorders.
Journal Article
Mitochondrial respiratory function in human platelets: Influence of sample preparation, assay buffer, and instrumental platform
by
Pavliv, Oleksandra
,
Cotter, Matthew
,
Diaz Fuentes, Eva C.
in
Adult
,
Bioenergetics
,
Blood cells
2025
Circulating blood cells such as platelets represent a readily available sample type to determine mitochondrial function in humans. Here, we set out to determine the influence of sample preparation, assay buffer composition, and instrumental platform on the respiratory function of platelets isolated from human blood. Approximately 50 mL of whole blood was collected from healthy adults (n = 16) following an overnight (>12 h) fast. Platelets were immediately isolated from whole blood by centrifugation for respirometry. Respiratory function was assayed in intact and permeabilized platelets using an Oxygraph‐2K (O2K) high‐resolution respirometer in either RPMI or MIR05 (containing 5 mM glucose, 1 mM pyruvate, and 2 mM glutamine), or the participant's own plasma. In addition, respiratory function was determined in intact platelets using a Seahorse Extracellular Flux analyzer (XFe96) in RPMI buffer containing 1 mM pyruvate, 2 mM glutamine, and variable glucose concentrations (5, 10, and 10 mM). In assays performed in an O2K, routine and ATP‐linked respiration were greater in cells assayed in RPMI compared to MIR05 (p < 0.001). However, compared to cells assayed in RPMI or MIR05, routine and ATP‐linked respiration were higher in intact platelets assayed in their own plasma (p < 0.001). In digitonin‐permeabilized platelets, state 3 respiration was greater when assayed in MIR05 compared to RPMI (p < 0.05). Across instrumental platforms, routine and leak respiration were lower in intact platelets assayed on an O2K versus an XFe96 (p < 0.05), whereas respiration available for ADP phosphorylation was greater in cells assayed on an O2K versus an XFe96 (p < 0.001), due to a diminished coupling response to oligomycin in cells assayed on the XFe96 (p < 0.001). Platelet respiratory function is influenced by assay buffer composition and instrumental platform. Consideration of these factors should be made by investigators planning to use platelet respiratory function as a readout of cellular energetics.
Journal Article
Supervised Resistance Training on Functional Capacity, Muscle Strength and Vascular Function in Peripheral Artery Disease: An Updated Systematic Review and Meta-Analysis
2021
Supervised resistance training appears to be a promising alternative exercise modality to supervised walking in patients with peripheral artery disease (PAD). This meta-analysis examined the efficacy of supervised RT for improving walking capacity, and whether adaptations occur at the vascular and/or skeletal muscle level in PAD patients. We searched Medline, CINAHL, Scopus, and Cochrane Central Register of Controlled Trials databases for randomized controlled trials (RCTs) in PAD patients testing the effects of supervised RT for ≥4 wk. on walking capacity, vascular function, and muscle strength. Pooled effect estimates were calculated and evaluated using conventional meta-analytic procedures. Six RCTs compared supervised RT to standard care. Overall, supervised RT prolonged claudication onset distance during a 6-min walk test (6-MWT) (101.7 m (59.6, 143.8), p < 0.001) and improved total walking distance during graded treadmill walking (SMD: 0.67 (0.33, 1.01), p < 0.001) and the 6-MWT (49.4 m (3.1, 95.6), p = 0.04). Five RCTS compared supervised RT and supervised intermittent walking, where the differences in functional capacity between the two exercise modalities appear to depend on the intensity of the exercise program. The insufficient evidence on the effects of RT on vascular function and muscle strength permitted only limited exploration. We conclude that RT is effective in prolonging walking performance in PAD patients. Whether RT exerts its influence on functional capacity by promoting blood flow and/or enhancing skeletal muscle strength remains unclear.
Journal Article
Rehabilitative Exercise Training for Burn Injury
by
Crandall, Craig G.
,
Palackic, Alen
,
Suman, Oscar E.
in
Body composition
,
Body mass
,
Bone density
2021
Due to improvements in acute burn care over the last few decades, most patients with severe burns (up to 90% of the total body surface) survive. However, the metabolic and cardiovascular complications that accompany a severe burn can persist for up to 3 years post injury. Accordingly, there is now a greater appreciation of the need for strategies that can hasten recovery and reduce long-term morbidity post burn. Rehabilitation exercise training (RET) is a proven effective treatment to restore lean body mass, glucose and protein metabolism, cardiorespiratory fitness, and muscle strength in burn survivors. Despite this, very few hospitals incorporate RET in programs to aid the rehabilitation of patients with severe burns. Given that RET is a safe and efficacious treatment that restores function and reduces post-burn morbidity, we propose that a long-term exercise prescription plan should be considered for all patients with severe burns. In this literature review, we discuss the current understanding of burn trauma on major organ systems, and the positive benefits of incorporating RET as a part of the long-term rehabilitation of severely burned individuals. We also provide burn-specific exercise prescription guidelines for clinical exercise physiologists.
Journal Article
Effective Function Annotation through Catalytic Residue Conservation
by
George, Richard A.
,
Swindells, Mark B.
,
Porter, Craig T.
in
Active sites
,
Amino Acid Sequence
,
Animals
2005
Because of the extreme impact of genome sequencing projects, protein sequences without accompanying experimental data now dominate public databases. Homology searches, by providing an opportunity to transfer functional information between related proteins, have become the de facto way to address this. Although a single, well annotated, close relationship will often facilitate sufficient annotation, this situation is not always the case, particularly if mutations are present in important functional residues. When only distant relationships are available, the transfer of function information is more tenuous, and the likelihood of encountering several well annotated proteins with different functions is increased. The consequence for a researcher is a range of candidate functions with little way of knowing which, if any, are correct. Here, we address the problem directly by introducing a computational approach to accurately identify and segregate related proteins into those with a functional similarity and those where function differs. This approach should find a wide range of applications, including the interpretation of genomics/proteomics data and the prioritization of targets for high-throughput structure determination. The method is generic, but here we concentrate on enzymes and apply high-quality catalytic site data. In addition to providing a series of comprehensive benchmarks to show the overall performance of our approach, we illustrate its utility with specific examples that include the correct identification of haptoglobin as a nonenzymatic relative of trypsin, discrimination of acid-D-amino acid ligases from a much larger ligase pool, and the successful annotation of BioH, a structural genomics target.
Journal Article
Characterizing Human Milk RNA Degradation Over Time to Optimize Storage of Human Milk for RNA Quality
2026
Human milk is rich in bioactive components beyond nutrition, including RNAs-especially miRNAs. It is the most RNA-rich biofluid. While storage effects on other milk components are well studied, RNA preservation has been minimally explored, primarily focusing on miRNAs in exosomes under refrigeration. The goal of this clinical study was to determine optimal collection and storage methods to preserve RNA quantity and quality in human milk, predominantly focusing on RNA stability in research laboratory settings when isolation of milk fat globules is not feasible. The study recruited 30 lactating women in central Arkansas. Milk samples were collected in-clinic and processed immediately for baseline RNA data. Remaining aliquots were stored at 4 °C, -20 °C, or -80 °C with or without RNAlater. RNA was extracted at 4 h, 24 h, 1 week, 4 weeks, 12 weeks, and 24 weeks using Qiagen miRNeasy and MinElute kits. RNA quality (RINe) and concentration (ng/µL) were assessed with Agilent TapeStation with additional quality analysis through qPCR. RNA quality declined over time at all storage temperatures in samples without RNAlater. Addition of RNAlater prevented decreases in RINe scores at most time points, maintaining RINe > 7 for up to 6 months, though it reduced total RNA concentration. qPCR also showed improved mRNA stability with RNAlater. miRNAs were analyzed using Agilent Bioanalyzer Small RNA kits with qPCR for quality analysis. RNAlater was not beneficial for miRNA preservation, and miRNAs remained stable when stored frozen without RNAlater. qPCR verified miRNA stability when frozen. In conclusion, RNA in human milk degrades over time. For mRNA analysis, storage with RNAlater at -80 °C is recommended. For miRNA analysis, storage at -20 °C or -80 °C without preservatives is optimal. These findings offer preliminary guidance for HM RNA storage, and researchers are advised to conduct method testing before full study implementation.
Journal Article
New Testament text and language : a Sheffield reader
by
Evans, Craig A.
,
Porter, Stanley E.
in
Bible. N.T. -- Criticism, Textual
,
Bible.-New Testament-Criticism, Textual
,
RELIGION
1997
The Sheffield Reader series collects the best articles on a specific topic from the Journal for the Study of the New Testament. The range of each volume reflects the breadth of the journal itself. Hence the reader will find groundbreaking studies that introduce new critical questions and move into fresh areas of enquiry, surveys of the state of play in a particular topic, and articles that engage with each other in specific debates. For undergraduates these books offer an invaluable critical introduction to a particular subject. More advanced students and scholars can use the volumes to find background material for their own area of interest, or to gain an overview of the research in an area outside their speciality.