Research Spotlight

Posted February 19th 2016

Quantitative Organic Acids in Urine by Two Dimensional Gas Chromatography-Time of Flight Mass Spectrometry (GCxGC-TOFMS).

Lawrence Sweetman Ph.D.

Lawrence Sweetman Ph.D.

Sweetman, L., P. Ashcraft and J. Bennett-Firmin (2016). “Quantitative Organic Acids in Urine by Two Dimensional Gas Chromatography-Time of Flight Mass Spectrometry (GCxGC-TOFMS).” Methods Mol Biol 1378: 183-197.

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Seventy-six organic acids in urine specimens are determined with quantitative two dimensional Gas Chromatography-Time of Flight Mass Spectrometry (GCxGC-TOFMS). The specimen is treated with urease to remove urea then derivatized to form pentafluorobenzyl oximes (PFBO) of oxoacids. The sample is then treated with ethyl alcohol to precipitate proteins and centrifuged. After drying the supernatant, the organic acids are derivatized to form volatile trimethylsilyl (TMS) derivatives for separation by capillary two dimensional Gas Chromatography (GCxGC) with temperature programming and modulation. Detection is by Time of Flight Mass Spectrometry (TOFMS) with identification of the organic acids by their mass spectra. Organic acids are quantitated by peak areas of reconstructed ion chromatograms with internal standards and calibration curves. Organic acids are quantified to determine abnormal patterns for the diagnosis of more than 100 inherited disorders of organic acid metabolism. Characteristic abnormal metabolites are quantified to monitor dietary and other modes of treatment for patients who are diagnosed with specific organic acid disorders.


Posted February 19th 2016

Multispectral and Photoplethysmography Optical Imaging Techniques Identify Important Tissue Characteristics in an Animal Model of Tangential Burn Excision.

J. Michael DiMaio M.D.

J. Michael DiMaio, M.D.

Thatcher, J. E., W. Li, Y. Rodriguez-Vaqueiro, J. J. Squiers, W. Mo, Y. Lu, K. D. Plant, E. Sellke, D. R. King, W. Fan, J. A. Martinez-Lorenzo and J. M. DiMaio (2016). “Multispectral and Photoplethysmography Optical Imaging Techniques Identify Important Tissue Characteristics in an Animal Model of Tangential Burn Excision.” J Burn Care Res 37(1): 38-52.

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Burn excision, a difficult technique owing to the training required to identify the extent and depth of injury, will benefit from a tool that can cue the surgeon as to where and how much to resect. We explored two rapid and noninvasive optical imaging techniques in their ability to identify burn tissue from the viable wound bed using an animal model of tangential burn excision. Photoplethysmography (PPG) imaging and multispectral imaging (MSI) were used to image the initial, intermediate, and final stages of burn excision of a deep partial-thickness burn. PPG imaging maps blood flow in the skin’s microcirculation, and MSI collects the tissue reflectance spectrum in visible and infrared wavelengths of light to classify tissue based on a reference library. A porcine deep partial-thickness burn model was generated and serial tangential excision accomplished with an electric dermatome set to 1.0 mm depth. Excised eschar was stained with hematoxylin and eosin to determine the extent of burn remaining at each excision depth. We confirmed that the PPG imaging device showed significantly less blood flow where burn tissue was present, and the MSI method could delineate burn tissue in the wound bed from the viable wound bed. These results were confirmed independently by a histological analysis. We found these devices can identify the proper depth of excision, and their images could cue a surgeon as to the preparedness of the wound bed for grafting. These image outputs are expected to facilitate clinical judgment in the operating room.


Posted February 19th 2016

Validation of a brief, two-question depression screen in trauma patients.

Ann M. Warren Ph.D.

Ann M. Warren, Ph.D.

Warren, A. M., M. Reynolds, M. L. Foreman, M. M. Bennett, R. J. Weddle, J. D. Austin, K. Roden-Foreman and L. B. Petrey (2016). “Validation of a brief, two-question depression screen in trauma patients.” J Trauma Acute Care Surg 80(2): 318-323.

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BACKGROUND: Increasingly, depression following traumatic injury is recognized as a complication of injury. Unlike mandated screening for risky alcohol use in trauma centers, screening for psychological risks is not required by the American College of Surgeons’ Committee on Trauma. Limited resources and time constraints are commonly given reasons against routine screening. The purpose of this study was to determine if a two-item screen was as valid as an eight-question screen for depression. METHODS: A total of 421 patients were given the Patient Health Questionnaire 8 (PHQ-8) during initial hospitalization to assess depression in a prospective study at a Level I trauma center. A cutoff score of 10 or higher (possible range, 0-24) on the PHQ-8 is used as diagnostic for depression. The PHQ-2 (possible range, 0-6) is derived from the first two questions of the PHQ-8 and contains items assessing sad mood and loss of interest/pleasure during the previous 2 weeks. A cutoff score of 3 or higher was considered to be a positive screen result. Discriminatory ability of the PHQ-2 was calculated. RESULTS: The sample was predominantly male (65%) and white (67%). The majority (85%) sustained a blunt trauma, and the primary cause of injury was motor vehicle collision (37%), with a mean Injury Severity Score (ISS) of 11.6. A total of 142 patients (34%) were positive for depression on the PHQ-8. When comparing the PHQ-2 with the PHQ-8, a sensitivity of 76.1 and a specificity of 92.8 were found, as well as a positive predictive value of 84.4. CONCLUSION: The result of our study confirms that depression is a frequent condition (34%) among individuals who sustain physical injury. The PHQ-2 seems to have acceptable sensitivity and specificity to identify depression in this population. The use of a two-item screening questionnaire is a minimal addition to the evaluation of patients after injury, allowing for earlier intervention and better outcomes. LEVEL OF EVIDENCE: Diagnostic study, level IV; prognostic/epidemiologic study, level III.


Posted February 19th 2016

Desired Improvement Tool (DIT): A tool to assess desire for improvement in psoriasis patients.

Daniel Zaghi M.D.

Daniel Zaghi. M.D.

Zaghi, D., C. Weir, J. Ying, C. Carlin, T. Greene, R. DeShazo, K. Callis Duffin and G. G. Krueger (2016). “Desired Improvement Tool (DIT): A tool to assess desire for improvement in psoriasis patients.” J Dermatolog Treat 27(1): 27-30.

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No validated instrument exists to measure desire for improvement in psoriasis patients. To address this void, we conducted a single-center longitudinal study of 268 moderate-to-severe psoriasis patients to psychometrically validate the Desired Improvement Tool (DIT). The DIT is a single-item instrument scored 0-5 by the patient. A 0 indicates the patient is satisfied with disease level and does not desire further treatment. A 5 indicates a large amount of improvement is desired. The DIT demonstrated high test-retest reliability (Spearman, r = 0.97). Predictive and construct validity were moderate-to-high: r = 0.70 for BSA, 0.67 for PASI, and 0.56 for PGA and r = 0.67 for Life Quality Assessment (LQA), respectively. A sensitivity analysis revealed the DIT responded to changes in BSA. As a psychometrically valid tool, the DIT may guide clinical management of psoriasis patients by capturing an important clinical construct in an expedient and quantifiable manner.


Posted February 19th 2016

Comparison of Transesophageal and Transthoracic Echocardiographic Measurements of Mechanism and Severity of Mitral Regurgitation in Ischemic Cardiomyopathy (from the Surgical Treatment of Ischemic Heart Failure Trial).

Paul A. Grayburn M.D.

Paul A. Grayburn, M.D.

Grayburn, P. A., L. She, B. J. Roberts, K. S. Golba, K. Mokrzycki, J. Drozdz, A. Cherniavsky, R. Przybylski, K. Wrobel, F. M. Asch, T. A. Holly, H. Haddad, M. Yii, G. Maurer, I. Kron, H. Schaff, E. J. Velazquez and J. K. Oh (2015). “Comparison of Transesophageal and Transthoracic Echocardiographic Measurements of Mechanism and Severity of Mitral Regurgitation in Ischemic Cardiomyopathy (from the Surgical Treatment of Ischemic Heart Failure Trial).” Am J Cardiol 116(6): 913-918.

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Mitral regurgitation (MR) is common in ischemic heart disease and contributes to symptoms and mortality. This report compares the results of baseline transesophageal echocardiography (TEE) and transthoracic echocardiography (TTE) imaging of the mechanism and severity of functional MR in patients with ischemic cardiomyopathy in the Surgical Treatment for Ischemic Heart Failure (STICH) trial. Independent core laboratories measured both TTE and TEE images on 196 STICH participants. Common measurements to both models included MR grade, mitral valve tenting height and tenting area, and mitral annular diameter. For each parameter, correlations were assessed using Spearman rank correlation coefficients. A modest correlation was present between TEE and TTE for overall MR grade (n = 176, r = 0.52). For mechanism of MR, modest correlations were present for long-axis tenting height (n = 152, r = 0.35), tenting area (n = 128, r = 0.27), and long-axis mitral annulus diameter (n = 123, r = 0.41). For each measurement, there was significant scatter. Potential explanations for the scatter include different orientation of the imaging planes between TEE and TTE, a mean temporal delay of 6 days between TEE and TTE, and statistically significant differences in heart rate and blood pressure and weight between studies. In conclusion, TEE and TTE measurements of MR mechanism and severity correlate only modestly with enough scatter in the data that they are not interchangeable.