Binna Choi

Firefighters and police officers have the third highest prevalence of obesity among 41 male occupational groups in the United States. However, few studies have examined the relationship of firefighter working conditions and health behaviors with obesity. This paper presents a theoretical framework describing the relationship between working conditions, health behaviors, and obesity in firefighters. In addition, the paper describes a detailed study plan for exploring the role of occupational and behavioral risk factors in the development of obesity in firefighters enrolled in the Orange County Fire Authority Wellness Fitness Program. The study plan will be described with emphasis on its methodological merits: adopting a participatory action research approach, developing a firefighter-specific work and health questionnaire, conducting both a cross-sectional epidemiological study using the questionnaire and a sub-study to assess the validity of the questionnaire with dietary intake and physical activity measures, and evaluating the strengths and weaknesses of the body mass index as an obesity measure in comparison to skinfold-based percent body fat. The study plan based on a theoretical framework can be an essential first step for establishing effective intervention programs for obesity among professional and voluntary firefighters. Copyright © 2011 by Safety and Health at Work.

Background: Pulsed dye laser is the gold standard for treatment of port-wine stain birthmarks but multiple treatments are required and complete resolution is often not achieved. Posttreatment vessel recurrence is thought to be a factor that limits efficacy of PDL treatment of PWS. Imiquimod 5% cream is an immunomodulator with antiangiogenic effects. Objective: We sought to determine if application of imiquimod 5% cream after PDL improves treatment outcome. Methods: Healthy individuals with PWS were treated with PDL and then randomized to apply posttreatment placebo or imiquimod 5% cream for 8 weeks. Chromameter measurements for 57 PWS sites were taken at baseline and compared with measurements taken 8 weeks posttreatment. The Δa and ΔE were measured to quantify treatment outcome. Results: Two patients developed minor skin irritation. Other adverse effects were not noted. Average a was 0.43 for PDL + placebo sites and 1.27 for PDL + imiquimod sites indicating a greater reduction in erythema with imiquimod. Average E was 2.59 for PDL + placebo and 4.08 for PDL + imiquimod, again indicating a greater color improvement with imiquimod. Limitations: Effects were evaluated after a single treatment and duration of effect is unknown. Conclusion: Combined selective photothermolysis and antiangiogenic therapy may enhance PWS treatment efficacy. © 2011 by the American Academy of Dermatology, Inc.

Background: Pulsed dye laser is a commonly utilized treatment for port wine stain birthmarks in the United States; however, results are variable and few patients achieve complete removal. Photodynamic therapy is commonly used in China, but treatment associated photosensitivity lasts several weeks and scarring may occur. We propose an alternative treatment option, combined PDT + PDL and performed a proof-of-concept preliminary clinical trial. Methods: Subjects with non-facial PWS were studied. Each subject had four test sites: control, PDL alone, PDT alone, and PDT + PDL. Radiant exposure time for PDT was increased in increments of 15 J/cm2. Authors evaluated photographs and chromametric measurements before and 12 weeks post-treatment. Results: No serious adverse events were reported; epidermal changes were mild and self-limited. No clinical blanching was noted in control or PDT-alone sites. At PDT radiant exposures of 15 and 30 J/cm2, equivalent purpura and blanching was observed at PDL and PDT + PDL sites. At PDT radiant exposures over 30 J/cm2, greater purpura was noted at PDT + PDL sites as compared to PDL alone. Starting at 75 J/cm2, improved blanching was noted at PDT + PDL sites. Conclusions: Preliminary results indicate that PDT + PDL is safe and may offer improved PWS treatment efficacy. Additional studies are warranted. © 2009 Elsevier B.V. All rights reserved.

Previous studies suggest that optimal port wine stain laser treatment parameters require knowledge of skin characteristics such as blood vessel size, depth, and distribution. Effective and rapid imaging modalities are not widely available. In the present study, photothermal tomography images of an in vivo hamster window model and human PWS skin were obtained and analyzed. Subtherapeutic laser light pulses at 585 and 600 nm were applied to skin surface and image sequences acquired with an infrared camera. A nonnegatively constrained conjugate gradient algorithm was used to reconstruct a PTT image of the initial temperature distribution immediately following pulsed laser irradiation. Vessel dimensions determined from PTT images of hamster window model skin compared well with those measured directly using video microscopy. PTT images of human PWS skin contained vessels with estimated diameters of 200-250 μm over a 250-320 μm depth range. Use of dual wavelength excitation analysis allowed for imaging of shallow vessels.

Port-wine stain birthmarks are one class of benign congenital vascular malformation. Laser therapy is the most successful treatment modality of PWS. Unfortunately, this approach has limited efficacy, with only 10% of patients experiencing complete blanching of the PWS. To address this problem, several research groups have developed technologies and methods designed to study treatment outcome and improve treatment efficacy. This article reviews seven optical imaging techniques currently in use or under development to assess treatment efficacy, focusing on: reflectance spectrophotometers/tristimulus colorimeters; laser Doppler flowmetry and laser Doppler imaging; cross-polarized diffuse reflectance colour imaging system; reflectance confocal microscopy; optical coherence tomography; spatial frequency domain imaging; and laser speckle imaging. © 2012 The Authors. BJD © 2012 British Association of Dermatologists 2012.

Background and Objective Current treatments of port-wine stain birthmarks typically involve use of a pulsed dye laser combined with cooling of the skin. Currently, PDL therapy protocols result in varied success, as some patients experience complete blanching, while others do not. Over the past decade, we have studied the use of photodynamic therapy as either a replacement or adjuvant treatment option to photocoagulate both small and large vasculature. The objective of the current study was to evaluate a PDT protocol that involves use of an alternate intravascular photosensitizer mono-L-aspartylchlorin-e6 activated by an array of low-cost light emitting diodes. Study Design/Materials and Methods To monitor the microvasculature, a dorsal window chamber model was installed on 22 adult male mice. The light source consisted of a custom-built LED array that emitted 10 W at a center wavelength of 664 nm. The light source was positioned at a fixed distance from the window chamber to achieve a fixed irradiance of 127 mW/cm 2. A retroorbital injection of NPe6 was performed to deliver the drug into the bloodstream. Laser irradiation was initiated immediately after injection. To monitor blood-flow dynamics in response to PDT, we used laser speckle imaging. We employed a dose-response experimental design to evaluate the efficacy of NPe6-mediated PDT. Results We observed three general hemodynamic responses to PDT: At low radiant exposures, we did not observe any persistent vascular shutdown; at intermediate radiant exposures, we observed an acute decrease in blood flow followed by gradual restoration of blood flow over the 7-day monitoring period; and at high radiant exposures, we observed acute vascular shutdown that persisted during the entire 7-day monitoring period. Dose-response analysis enabled identification of 85 J/cm 2 as a characteristic radiant exposure required to achieve persistent vascular shutdown at Day 7 following PDT. Conclusion The experimental data suggest that NPe6-mediated PDT can achieve persistent vascular shutdown of normal microvasculature. © 2012 Wiley Periodicals, Inc.

Background and Objective: During laser therapy of port wine stain birthmarks, regions of perfusionmay persist. We hypothesize that such regions are not readily observable even when laser surgery is performed by highly experienced clinicians. The objective of this study was to use objective feedback to assess the acute vascular response to laser therapy. Study Design/Materials and Methods: A clinic-friendly laser speckle imaging instrument was developed to provide the clinician with real-time images of blood flow during laser therapy. Images were acquired from patients undergoing laser therapy of PWS birthmarks at Scripps Clinic and the Beckman Laser Institute and Medical Clinic. Blood flow maps were extracted from the acquired imaging data. Histogram-based analysis was applied in grading the degree of heterogeneity present in the blood flow maps after laser therapy. Results: Collectively, two types of patient responses were observed in response to laser exposure: an immediate increase in perfusion within minutes after laser therapy; and an overall decrease in blood perfusion ∼1 hour after laser therapy, with distinct regions of persistent perfusion apparent in the majority of post-treatment blood-flow images. A comparison of blood flow in PWS and adjacent normal skin demonstrated that PWS blood flow can be greater than, or sometimes equivalent to, that of normal skin. Conclusion: In general, a decrease in skin perfusion is observed during pulsed laser therapy of PWS birthmarks. However, a heterogeneous perfusion map was frequently observed. These regions of persistent perfusion may be due to incomplete photocoagulation of the targeted vessels. We hypothesize that immediate retreatment of these regions identified with LSI, will result in enhanced removal of the PWS vasculature. © 2009 Wiley-Liss, Inc.

Background and Objective: Pulsed dye laser treatment of cutaneous vascular lesions is associated with variable and unpredictable efficacy. Thus, alternative treatment modalities are needed. Previous in vitro and in vivo studies have demonstrated enhanced selective vascular destruction with benzoporphyrin derivative monoacid ring A photodynamic therapy followed immediately by PDL irradiation. Here, we evaluate PDT alone, PDL alone, and PDT+PDL protocols using an optimized in vivo rodent dorsal window chamber model. Study Design/Materials and Methods: A dorsal window chamber was surgically installed on male Golden Syrian hamsters. BPD solution was administered intravenously via a jugular venous catheter. Evaluated interventions included: Control ; Control ; PDT alone ; PDL alone at 7 J/cm 2 ; and PDT +PDL. Laser speckle imaging was used to monitor blood flow dynamics before, immediately after, and 1, 3, and 5 days post-intervention. Results: Perfusion reduction on day 1 post-intervention was achieved with PDT>50 J/cm2, PDL alone, and PDT+PDL. However, by day 5 post-intervention, recovery of flow was observed with PDT alone at 50 J/cm2 and PDL alone. PDT +PDL resulted in the greatest prolonged reduction in vascular perfusion. Conclusions: Our in vivo data suggest that the PDT+PDL therapeutic protocol can result in enhanced and persistent vascular shutdown compared to PDT or PDL alone. The PDT+PDL approach has potential for considerable superficial vascular destruction and should be considered as a treatment modality for cutaneous vascular lesions. Monitoring of blood flow changes for as long as possible is crucial for accurate assessment of light-based vascular interventions. © 2008 Wiley-Liss, Inc.

Background and Objectives: Previous in vitro studies demonstrated the potential utility of benzoporphyrin derivative monoacid ring A photodynamic therapy for vascular destruction. Moreover, the effects of PDT were enhanced when this intervention was followed immediately by pulsed dye laser irradiation. We further evaluate vascular effects of PDT alone, PDL alone and PDT/PDL in an in vivo rodent dorsal skinfold model. Study Design/Materials and Methods: A dorsal skin-fold window chamber was installed surgically on female Sprague-Dawley rats. One milligram per kilogram of BPD solution was administered intravenously via a jugular venous catheter. Evaluated interventions were: control, PDT alone, PDL alone at 7 J/cm2, PDL alone at 10 J/cm2, PDT/PDL, and PDT/PDL. To assess changes in microvascular blood flow, laser speckle imaging was performed before, immediately after, and 18 hours post-intervention. Results: Epidermal irradiation was accomplished without blistering, scabbing or ulceration. A reduction in perfusion was achieved in all intervention groups. PDT/PDL at 7 J/ cm2 resulted in the greatest reduction in vascular perfusion. Conclusions: BPD PDT can achieve safe and selective vascular flow reduction. PDT/PDL can enhance diminution of microvascular blood flow. Our results suggest that PDT and PDT/PDL should be evaluated as alternative therapeutic options for treatment of hypervascular skin lesions including port wine stain birthmarks. © 2006 Wiley-Liss, Inc.

Port-wine stain birthmarks are congenital, low-flow vascular malformations of the skin. Lasers are the modality of choice for the treatment of PWS birthmarks, and for most patients the pulsed-dye laser in conjunction with epidermal cooling offers the greatest efficacy and safety. Other light devices, including the 532-nm frequency-doubled Nd:YAG laser, intense pulsed light, 1064-nm Nd:YAG laser, and combined 1064/532-nm system, may be useful during a treatment course for resistant PWS. Laser treatment results in blanching of most lesions, although complete resolution may not occur and some resistant PWS birthmarks respond minimally, if at all. Factors limiting laser treatment include variable vascular geometry, inadequate damage of some vessels, and lesional posttreatment recurrence as a result of neovascularization. Alternative or adjunct treatment options that address these limitations should be explored, including noninvasive real-time imaging to optimize the selection of treatment settings, photodynamic therapy, and perioperative use of antiangiogenic compounds.

Background and Objective: Although cryogen spray cooling is used to minimize the risk of epidermal damage during laser dermatologic surgery, concern has been expressed that CSC may induce cryo-injury. The objective of this study is to measure temperature variations at the epidermal-dermal junction in ex vivo human skin during three clinically relevant multiple cryogen spurt-laser pulse sequences. Study Design/Materials and Methods: The epidermis of ex vivo human skin was separated from the dermis and a thin-foil thermocouple was inserted between the two layers. Thermocouple depth and epidermal thickness were measured using optical coherence tomography. Skin specimens were preheated to 30°C before the MCS-LPS were initiated. Three MCS-LPS patterns, with total cryogen spray times of 38, 30, and 25 milliseconds respectively, were applied to the specimens in combination with laser fluences of 10 and 14 J/cm2, while the thermocouple recorded the temperature changes at the epidermal-dermal junction. Results: The thermocouple effectively recorded fast temperature changes during three MCS-LPS patterns. The lowest temperatures measured corresponded to the sequences with longer pre-cooling cryogen spurts. No subzero temperatures were measured for any of the MCS-LPS patterns under study. Conclusions: The three clinically relevant MCS-LPS patterns evaluated in this study do not cause sub-zero temperatures in ex vivo human skin at the epidermal-dermal junction and, therefore, are unlikely to cause significant cryogen induced epidermal injury. © 2006 Wiley-Liss, Inc.

Background and Objectives: Quantitative methods to assess port wine stain skin response to laser therapy are needed to improve therapeutic outcome. In this study, PWS skin erythema was analyzed using erythema index difference images before and after treatment to investigate systematically subject-dependent response to laser therapy. Study Design/Materials and Methods: Cross-polarized digital skin color images were acquired from 17 subjects with facial PWS and the associated ΔEI images were computed. Qualitative and quantitative analyses of PWS skin erythema were performed with ΔEI images, in which ranges of 40-6 and 5-0 represented PWS and normal skin, respectively. Results: After laser therapy, we qualitatively observed α reduction in the ΔEI values for all subjects. Regression fitting of ΔEI values before and after PWS laser therapy was associated with strong positive linear correlation. Conclusions: The imaging modality and analysis method allowed systematic analysis of PWS skin erythema in response to laser therapy. PWS skin response was dependent on pretreatment ΔEI values, suggesting that erythema can be utilized as an effective parameter to monitor PWS response to laser therapy. © 2005 Wiley-Liss, Inc.

Background and Objectives: Objective methods to assess quantitatively port wine stain blanching in response to laser therapy are needed to improve laser therapeutic outcome. Previous studies have attempted to assess objectively PWS color based on point measurement devices. To date, these approaches have typically been limited by a number of factors such as small test area and need for contact. To address these issues, a cross-polarized diffuse reflectance imaging system and color image analysis method has been developed to evaluate quantitatively erythema and melanin content in PWS skin. Study Design/Materials and Methods: A cross-polarized diffuse reflectance system has been constructed to acquire high resolution digital images while minimizing artifacts such as glare, shadowing, and nonuniform illumination effects that can compromise image fidelity. Furthermore, an image analysis algorithm has also been developed to analyze normal and PWS skin in terms of CIEL*a*b* color space parameters. Using the algorithm, images of color space intensity, L*, and saturation, a*, indices have been calculated to extract quantitative metrics of melanin and erythema, respectively. Results: Compared to the cross-polarized diffuse reflectance image, the a* index image enhanced the contrast in regions of high and low erythema and seems to have quasi correlation with the L* index image. In the presented PWS patient example, the relative a* index difference image showed less erythema in PWS skin after laser treatment when compared to pre-treatment values. Conclusions: Our cross-polarized imaging system and color image analysis method is a simple, noncontact technique that can indirectly provide quantitative measurement of erythema and melanin content in PWS skin. © 2004 Wiley-Liss, Inc.

Background and Objective The pulpal chamber of each tooth contains the vasculature necessary to maintain a viable tooth. A critical need exists to develop an objective, repeatable method to assess pulpal viability. We hypothesized that the existence of blood perfusion within the pulp can be determined with analysis of laser speckle imaging patterns generated by transillumination of the tooth. Study Design/Materials and Methods We used nine extracted human cuspids and incisors. A Tygon tube was inserted into a channel created within each tooth and Intralipid pumped through the tube in a controlled manner with a syringe infusion pump. We evaluated the feasibility of LSI for flow assessment using both transillumination and epiillumination imaging configurations. With the transillumination geometry, we also assessed the effect of the angle of incidence of the probe laser light on the speckle flow index values extracted from the collected speckle images. Results Transillumination LSI, and not epiillumination LSI, enables differentiation between the absence and presence of perfusion in an in vitro tooth model. SFI values are insensitive to the relative angle of incidence of the laser light, over a wide range of angles. Conclusions Our preliminary in vitro data suggest that transillumination LSI is a promising method to identify the presence of blood flow in the pulpal chamber. Future in vivo evaluation is warranted. © 2011 Wiley-Liss, Inc.

The turbidity of most biologic tissues hinders the use of lasers for diagnostic and therapeutic purposes. Hyperosmotic agents such as glycerol have been used to alter the optical scattering properties of turbid tissues. The mechanism of this effect, "optical clearing", however, remains incompletely understood. Multiphoton microscopy utilizing second harmonic generation can be used to monitor collagen structural changes in the presence of glycerol. This study suggests that the use of glycerol for tissue "optical clearing" screens noncovalent intermolecular interactions between low-order collagen structures, resulting in fiber disassembly. Dissociation of collagen fibers in native and engineered tissues in the presence of glycerol and reassociation with the application of saline are imaged dynamically. Collagen fiber reassembly is governed by the displacement of glycerol by saline in native and engineered skin. These results reveal the assembly process of high-order collagen structures and propose a molecular mechanism for the increase in tissue transparency observed after glycerol application.

© 2015 Elsevier Ltd and ISBI. All rights reserved. Surgical intervention of second degree burns is often delayed because of the difficulty in visual diagnosis, which increases the risk of scarring and infection. Non-invasive metrics have shown promise in accurately assessing burn depth. Here, we examine the use of spatial frequency domain imaging and laser speckle imaging for predicting burn depth. Contact burn wounds of increasing severity were created on the dorsum of a Yorkshire pig, and wounds were imaged with SFDI/LSI starting immediately after-burn and then daily for the next 4 days. In addition, on each day the burn wounds were biopsied for histological analysis of burn depth, defined by collagen coagulation, apoptosis, and adnexal/vascular necrosis. Histological results show that collagen coagulation progressed from day 0 to day 1, and then stabilized. Results of burn wound imaging using non-invasive techniques were able to produce metrics that correlate to different predictors of burn depth. Collagen coagulation and apoptosis correlated with SFDI scattering coefficient parameter and adnexal/vascular necrosis on the day of burn correlated with blood flow determined by LSI. Therefore, incorporation of SFDI scattering coefficient and blood flow determined by LSI may provide an algorithm for accurate assessment of the severity of burn wounds in real time.

Shift work and overtime have been implicated as important work-related risk factors for cardiovascular disease. Many firefighters who contractually work on a 24-hr work schedule, often do overtime which can result in working multiple, consecutive 24-hr shifts. Very little research has been conducted on firefighters at work that examines the impact of performing consecutive 24-hr shifts on cardiovascular physiology. Also, there have been no standard field methods for assessing in firefighters the cardiovascular changes that result from 24-hr shifts, what we call "cardiovascular strain". The objective of this study, as the first step toward elucidating the role of very long shifts in the development of CVD in firefighters, is to develop and describe a theoretical framework for studying cardiovascular strain in firefighters on very long shifts. The developed theoretical framework was built on an extensive literature review, our recently completed studies with firefighters in Southern California, e-mail and discussions with several firefighters on their experiences of consecutive shifts, and our recently conducted feasibility study in a small group of firefighters of several ambulatory cardiovascular strain biomarkers. The theoretical framework developed in this study will facilitate future field studies on consecutive 24-hr shifts and cardiovascular health in firefighters. Also it will increase our understanding of the mechanisms by which shift work or long work hours can affect CVD, particularly through CVD biological risk factors, and thereby inform policy about sustainable work and rest schedules for firefighters.