Last data update: Apr 29, 2024. (Total: 46658 publications since 2009)
Records 1-28 (of 28 Records) |
Query Trace: Law BF [original query] |
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Microrna-mediated Krüppel-Like Factor 4 upregulation induces alternatively activated macrophage-associated marker and chemokine transcription in 4,4'-methylene diphenyl diisocyanate exposed macrophages
Lin CC , Law BF , Hettick JM . Xenobiotica 2024 1-22 Occupational exposure to 4,4'-methylene diphenyl diisocyanate (MDI) is associated with occupational asthma (OA) development. Alveolar macrophage-induced recruitment of immune cells to the lung microenvironment plays an important role during asthma pathogenesis. Previous studies identified that MDI/MDI-glutathione (GSH)-exposure downregulates endogenous hsa-miR-206-3p/hsa-miR-381-3p. Our prior report shows that alternatively activated (M2) macrophage-associated markers/chemokines are induced by MDI/MDI-GSH-mediated Krüppel-Like Factor 4 (KLF4) upregulation in macrophages and stimulates immune cell chemotaxis. However, the underlying molecular mechanism(s) by which MDI/MDI-GSH upregulates KLF4 remain unclear.Following MDI-GSH exposure, microRNA(miR)-inhibitors/mimics or plasmid transfection, endogenous hsa-miR-206-3p/hsa-miR-381-3p, KLF4, or M2 macrophage-associated markers (CD206, TGM2), and chemokines (CCL17, CCL22, CCL24) were measured by either RT-qPCR, western blot, or luciferase assay.MDI-GSH exposure downregulates hsa-miR-206-3p/hsa-miR-381-3p by 1.46- to 9.75-fold whereas upregulates KLF4 by 1.68- to 1.99-fold, respectively. In silico analysis predicts binding between hsa-miR-206-3p/hsa-miR-381-3p and KLF4. Gain- and loss-of-function, luciferase reporter assays and RNA-induced silencing complex-immunoprecipitation (RISC-IP) studies confirm the posttranscriptional regulatory roles of hsa-miR-206-3p/hsa-miR-381-3p and KLF4 in macrophages. Furthermore, hsa-miR-206-3p/hsa-miR-381-3p regulate the expression of M2 macrophage-associated markers and chemokines via KLF4.In conclusion, hsa-miR-206-3p/hsa-miR-381-3p play a major role in regulation of MDI/MDI-GSH-induced M2 macrophage-associated markers and chemokines by targeting the KLF4 transcript, and KLF4-mediated regulation in macrophages. |
4,4'-Methylene diphenyl diisocyanate exposure induces expression of alternatively activated macrophage-associated markers and chemokines partially through Krüppel-like factor 4 mediated signaling in macrophages
Lin CC , Law BF , Hettick JM . Xenobiotica 2023 53 (12) 1-17 Occupational exposure to the most widely used monomeric diisocyanate (dNCO), 4,4'-methylene diphenyl diisocyanate (MDI), may lead to the development of occupational asthma (OA). Alveolar macrophages with alternatively activated (M2) phenotype have been implicated in allergic airway responses and the pathogenesis of asthma. Recent in vivo studies demonstrate that M2 macrophage-associated markers and chemokines are induced by MDI-exposure, however, the underlying molecular mechanism(s) by which this proceeds is unclear.Following MDI exposure (in vivo and in vitro) M2 macrophage-associated transcription factors (TFs), markers, and chemokines were determined by RT-qPCR, western blots, and ELISA.Expression of M2 macrophage-associated TFs and markers including Klf4/KLF4, Cd206/CD206, Tgm2/TGM2, Ccl17/CCL17, Ccl22/CCL22, and CCL24 were induced by MDI/MDI-GSH exposure in bronchoalveolar lavage cells (BALCs)/THP-1 macrophages. The expression of CD206, TGM2, CCL17, CCL22, and CCL24 are upregulated by 3.83-, 7.69-, 6.22-, 6.08-, and 1.90-fold in KLF4-overexpressed macrophages, respectively. Endogenous CD206 and TGM2 were downregulated by 1.65-5.17-fold, and 1.15-1.78-fold, whereas CCL17, CCL22, and CCL24 remain unchanged in KLF4-knockdown macrophages. Finally, MDI-glutathione (GSH) conjugate-treated macrophages show increased chemotactic ability to T-cells and eosinophils, which may be attenuated by KLF4 knockdown.Our data suggest that MDI exposure may induce M2 macrophage-associated markers partially through induction of KLF4. |
Efficacy of face masks, neck gaiters and face shields for reducing the expulsion of simulated cough-generated aerosols (preprint)
Lindsley WG , Blachere FM , Law BF , Beezhold DH , Noti JD . medRxiv 2020 2020.10.05.20207241 Face masks are recommended to reduce community transmission of SARS-CoV-2. One of the primary benefits of face masks and other coverings is as source control devices to reduce the expulsion of respiratory aerosols during coughing, breathing, and speaking. Face shields and neck gaiters have been proposed as an alternative to face masks, but information about face shields and neck gaiters as source control devices is limited. We used a cough aerosol simulator with a pliable skin headform to propel small aerosol particles (0 to 7 µm) into different face coverings. An N95 respirator blocked 99% of the cough aerosol, a medical grade procedure mask blocked 59%, a 3-ply cotton cloth face mask blocked 51%, and a polyester neck gaiter blocked 47% as a single layer and 60% when folded into a double layer. In contrast, the face shield blocked 2% of the cough aerosol. Our results suggest that face masks and neck gaiters are preferable to face shields as source control devices for cough aerosols.Competing Interest StatementThe authors have declared no competing interest.Funding StatementThis research was funded by the National Institute for Occupational Safety and Health (NIOSH), US Centers for Disease Control and Prevention (CDC).Author DeclarationsI confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.YesThe details of the IRB/oversight body that provided approval or exemption for the research described are given below:No IRB approval requiredAll necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived.YesI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).YesI have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable.YesExperimental data is available upon request. |
A comparison of performance metrics for cloth face masks as source control devices for simulated cough and exhalation aerosols (preprint)
Lindsley WG , Blachere FM , Beezhold DH , Law BF , Derk RC , Hettick JM , Woodfork K , Goldsmith WT , Harris JR , Duling MG , Boutin B , Nurkiewicz T , Noti JD . medRxiv 2021 Universal mask wearing is recommended by the Centers for Disease Control and Prevention to help control the spread of COVID-19. Masks reduce the expulsion of respiratory aerosols (called source control) and offer some protection to the wearer. However, masks vary greatly in their designs and construction materials, and it is not clear which are most effective. Our study tested 15 reusable cloth masks (which included face masks, neck gaiters, and bandanas), two medical masks, and two N95 filtering facepiece respirators as source control devices for aerosols ≤ 7 µm produced during simulated coughing and exhalation. These measurements were compared with the mask filtration efficiencies, airflow resistances, and fit factors. The source control collection efficiencies for the cloth masks ranged from 17% to 71% for coughing and 35% to 66% for exhalation. The filtration efficiencies of the cloth masks ranged from 1.4% to 98%, while the fit factors were 1.3 to 7.4 on an elastomeric manikin headform and 1.0 to 4.0 on human test subjects. The correlation coefficients between the source control efficacies and the other performance metrics ranged from 0.31 to 0.66 and were significant in all but one case. However, none of the alternative metrics were strong predictors of the source control performance of cloth masks. Our results suggest that a better understanding of the relationships between source control performance and metrics like filtration efficiency, airflow resistance, and fit factor are needed to develop simple methods to estimate the effectiveness of masks as source control devices for respiratory aerosols. |
MicroRNA-Mediated Calcineurin Signaling Activation Induces CCL2, CCL3, CCL5, IL8 and Chemotactic Activities in 4,4'-Methylene Diphenyl Diisocyanate Exposed Macrophages
Lin CC , Law BF , Hettick JM . Xenobiotica 2021 51 (12) 1-20 Occupational exposure to 4,4'-methylene diphenyl diisocyanate (MDI), the most widely used monomeric diisocyanate, is one of the leading causes of occupational asthma (OA). Previously, we identified microRNA (miR)-206-3p/miR-381-3p-mediated PPP3CA/calcineurin signaling regulated iNOS transcription in macrophages and bronchoalveolar lavage cells (BALCs) after acute MDI exposure; however, whether PPP3CA/calcineurin signaling participates in regulation of other asthma-associated mediators secreted by macrophages/BALCs after MDI exposure is unknown.Several asthma-associated, macrophage-secreted mediator mRNAs from MDI exposed murine BALCs and MDI-glutathione (GSH) conjugate treated differentiated THP-1 macrophages were analyzed using RT-qPCR.Endogenous IL1B, TNF, CCL2, CCL3, CCL5, and TGFB1 were upregulated in MDI or MDI-GSH conjugate exposed BALCs and macrophages, respectively. Calcineurin inhibitor tacrolimus (FK506) attenuated the MDI-GSH conjugate-mediated induction of CCL2, CCL3, CCL5, and CXCL8/IL8 but not others. Transfection of either miR-inhibitor-206-3p or miR-inhibitor-381-3p in macrophages induced chemokine CCL2, CCL3, CCL5, and CXCL8 transcription, whereas FK506 attenuated the miR-inhibitor-206-3p or miR-inhibitor-381-3p-mediated effects. Finally, MDI-GSH conjugate treated macrophages showed increased chemotactic ability to various immune cells, which may be attenuated by FK506.In conclusion, these results indicate that MDI exposure to macrophages/BALCs may recruit immune cells into the airway via induction of chemokines by miR-206-3p and miR-381-3p-mediated calcineurin signaling activation. |
A comparison of performance metrics for cloth masks as source control devices for simulated cough and exhalation aerosols.
Lindsley WG , Blachere FM , Beezhold DH , Law BF , Derk RC , Hettick JM , Woodfork K , Goldsmith WT , Harris JR , Duling MG , Boutin B , Nurkiewicz T , Boots T , Coyle J , Noti JD . Aerosol Sci Technol 2021 55 (10) 1125-1142 Universal mask wearing is recommended to help control the spread of COVID-19. Masks reduce the expulsion of aerosols of respiratory fluids into the environment (called source control) and offer some protection to the wearer. Masks are often characterized using filtration efficiency, airflow resistance, and manikin or human fit factors, which are standard metrics used for personal protective devices. However, none of these metrics are direct measurements of how effectively a mask blocks coughed and exhaled aerosols. We studied the source control performance of 15 cloth masks (face masks, neck gaiters, and bandanas), two medical masks, and two N95 filtering facepiece respirators by measuring their ability to block aerosols ≤7 µm expelled during simulated coughing and exhalation (called source control collection efficiency). These measurements were compared with filtration efficiencies, airflow resistances, and fit factors measured on manikin headforms and humans. Collection efficiencies for the cloth masks ranged from 17% to 71% for coughing and 35% to 66% for exhalation. Filtration efficiencies for the cloth masks ranged from 1.4% to 98%, while the fit factors were 1.3 to 7.4 on headforms and 1.0 to 4.0 on human subjects. The Spearman’s rank correlation coefficients between the source control collection efficiencies and the standard metrics ranged from 0.03 to 0.68 and were significant in all but two cases. However, none of the standard metrics were strongly correlated with source control performance. A better understanding of the relationships between source control collection efficiency, filtration efficiency, airflow resistance, and fit factor is needed. ©, This work was authored as part of the Contributor's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 USC. 105, no copyright protection is available for such works under US Law. |
Efficacy of face masks, neck gaiters and face shields for reducing the expulsion of simulated cough-generated aerosols.
Lindsley WG , Blachere FM , Law BF , Beezhold DH , Noti JD . Aerosol Sci Technol 2020 55 (4) [Epub ahead of print] Face masks are recommended to reduce community transmission of SARS-CoV-2. One of the primary benefits of face masks and other coverings is as source control devices to reduce the expulsion of respiratory aerosols during coughing, breathing, and speaking. Face shields and neck gaiters have been proposed as an alternative to face masks, but information about face shields and neck gaiters as source control devices is limited. We used a cough aerosol simulator with a pliable skin headform to propel small aerosol particles (0 to 7 ìm) into different face coverings. An N95 respirator blocked 99% (standard deviation (SD) 0.3%) of the cough aerosol, a medical grade procedure mask blocked 59% (SD 6.9%), a 3-ply cotton cloth face mask blocked 51% (SD 7.7%), and a polyester neck gaiter blocked 47% (SD 7.5%) as a single layer and 60% (SD 7.2%) when folded into a double layer. In contrast, the face shield blocked 2% (SD 15.3%) of the cough aerosol. Our results suggest that face masks and neck gaiters are preferable to face shields as source control devices for cough aerosols. |
Urushiol compounds detected in Toxicodendron-labeled consumer products using mass spectrometry
Zhang AJ , Aschenbeck KA , Law BF , B'Hymer C , Siegel PD , Hylwa SA . Dermatitis 2020 31 (2) 134-139 BACKGROUND: Urushiol, the culprit allergen in Toxicodendron plants such as poison ivy, is an oily mixture of 15 and 17 carbon side chain alk-(en)-yl catechols. Recently, consumer products have been identified that contain Toxicodendron as an ingredient on their label; however, no studies have assessed whether urushiol is indeed present within these products. OBJECTIVE: The aim of the study was to determine whether urushiol compounds are present in consumer products labeled as containing Toxicodendron species. METHODS: Gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry were performed on 9 consumer products labeled as containing Toxicodendron species, including topical homeopathic remedies. Single ion monitoring gas chromatography-mass spectrometry was programmed in selective ion mode to detect 3-methylcatechol characteristic fragment ions of alk-(en)-yl catechols after silanization. Similarly, single ion monitoring liquid chromatography-tandem mass spectrometry was programmed to detect 4 urushiol pentadecylcatechols and 5 urushiol heptadecylcatechols using previously reported mass-to-charge ratios. RESULTS: Gas chromatography-mass spectrometry detected alk-(en)-yl catechols in 67% (6/9) of the products tested. Liquid chromatography-tandem mass spectrometry detected multiple urushiol pentadecylcatechols and heptadecylcatechols in 44% (4/9) of the products tested. CONCLUSIONS: Alk-(en)-yl catechols and multiple urushiols were detected in consumer products listing Toxicodendron species as an ingredient. Clinicians should be aware of these known allergenic ingredients in consumer products. |
Acute 4,4'-methylene diphenyl diisocyanate exposure-mediated downregulation of miR-206-3p and miR-381-3p activates inducible nitric oxide synthase transcription by targeting calcineurin/NFAT signaling in macrophages
Lin CC , Law BF , Hettick JM . Toxicol Sci 2019 173 (1) 100-113 Exposure to 4,4'-methylene diphenyl diisocyanate (MDI) in the occupational setting may lead to development of occupational asthma (OA), and the underlying molecular mechanisms of MDI-induced disease pathogenesis remain an active area of research. Using a nose-only mouse inhalation model, we find that circulating microRNA (miR)-206-3p and miR-381-3p are downregulated after MDI exposure; however, cellular miR-206-3p and miR-381-3p responses after MDI aerosol exposure and their pathophysiological roles in MDI-OA are unknown. We hypothesize that miR-206-3p and miR-381-3p-regulated mechanisms cause increased expression of the inducible nitric oxide synthase (iNOS) after MDI aerosol exposure. We examined cellular miR-206-3p and miR-381-3p, calcineurins, nuclear factors of activated T-cells (NFATs) and iNOS levels from both nose-only exposed murine bronchoalveolar lavage cells (BALCs) and differentiated THP-1 macrophages treated with MDI-glutathione (GSH) conjugates. Both in vivo murine MDI aerosol exposure and in vitro MDI-GSH exposures in THP-1 macrophages results in downregulation of endogenous miR-206-3p and miR-381-3p and upregulation of PPP3CA and iNOS expression. Transfection of THP-1 macrophages with miR-inhibitor-206-3p and miR-inhibitor-381-3p resulted in the upregulation of PPP3CA and iNOS. Using RNA-induced silencing complex immunoprecipitation (RISC-IP) and translational reporter assays, we verified that PPP3CA, but not iNOS, is directly targeted by both miR-206-3p and miR-381-3p. Downregulation of miR-206-3p and miR-381-3p following by MDI exposure induces Calcineurin/NFAT signaling-mediated iNOS transcription in macrophages and BALCs. |
Etiological contact allergen chemical identification and confirmation
Siegel PD , Law BF , Warshaw EM . Dermatitis 2019 31 (2) 99-105 Identification of the etiological chemical agent(s) associated with a case(s) of allergic contact dermatitis (ACD) is important for both patient management and public health surveillance. Traditional patch testing can identify chemical allergens to which the patient is allergic. Confirmation of allergen presence in the causative ACD-associated material is presently dependent on labeling information, which may not list the allergenic chemical on the product label or safety data sheet. Dermatologists have expressed concern over the lack of laboratory support for chemical allergen identification and possibly quantification from patients' ACD-associated products. The aim of the study was to provide the clinician a primer to better understand the analytical chemistry of contact allergen confirmation and unknown identification, including types of analyses, required instrumentation, identification levels of confidence decision tree, limitations, and costs. |
Circulating miRs-183-5p, -206-3p and -381-3p may serve as novel biomarkers for 4,4'-methylene diphenyl diisocyanate exposure
Lin CC , Law BF , Siegel PD , Hettick JM . Biomarkers 2018 24 (1) 1-45 BACKGROUND: Occupational exposure to the most widely used diisocyanate, 4,4'-methylene diphenyl diisocyanate (MDI), is a cause of occupational asthma (OA). Early recognition of MDI exposure and sensitization is essential for the prevention of MDI-OA. OBJECTIVE: Identify circulating microRNAs (miRs) as novel biomarkers for early detection of MDI exposure and prevention of MDI-OA. MATERIALS AND METHODS: Female BALB/c mice were exposed to one of three exposure regimens: dermal exposure to 1% MDI in acetone; nose-only exposure to 4580 +/- 1497 mug/m(3) MDI-aerosol for 60 minutes; or MDI dermal exposure/sensitization followed by MDI-aerosol inhalation challenge. Blood was collected and miRCURY miRs qPCR Pro fi ling Service was used to profile circulating miRs from dermally exposed mice. Candidate miRs were identified and verified from mice exposed to three MDI-exposure regimens by TaqMan(R) miR assays. RESULTS: Up/down-regulation patterns of circulating mmu-miRs-183-5p, -206-3p and -381-3p were identified and verified. Circulating mmu-miR-183-5p was upregulated whereas mmu-miRs-206-3p and -381-3p were downregulated in mice exposed via all three MDI exposure regimens. DISCUSSION AND CONCLUSION: Upregulation of circulating miR-183-5p along with downregulation of circulating miRs-206-3p and -381-3p may serve as putative biomarkers of MDI exposure and may be considered as potential candidates for validation in exposed human worker populations. |
Mass spectrometry-based analysis of murine bronchoalveolar lavage fluid following respiratory exposure to 4,4'-methylene diphenyl diisocyanate aerosol
Hettick JM , Law BF , Lin CC , Wisnewski AV , Siegel PD . Xenobiotica 2017 48 (6) 1-32 Diisocyanates are highly reactive electrophiles utilized in the manufacture of a wide range of polyurethane products, and have been identified as causative agents of occupational allergic respiratory disease. However, in spite of the significant occupational health burden associated with diisocyanate-induced asthma, the mechanism of disease pathogenesis remains largely unknown. To better understand the fate of inhaled diisocyanates, a nose-only aerosol exposure system was constructed and utilized to expose a BALB/c mouse model to aerosol generated from 4,4'-methylene diphenyl diisocyanate (MDI). Tissue and bronchoalveolar lavage samples were evaluated 4 hours and 24 hours post-exposure for evidence of diisocyanate-protein haptenation, and a label-free quantitative proteomics strategy was employed to evaluate relative changes to protein content of the cellular fraction of the lavage fluid. Following MDI aerosol exposure, expression of a number of proteins with immunological or xenobiotic metabolism relevance is increased, including endoplasmin, cytochrome P450 and argininosuccinate synthase. Western blot analysis indicated MDI-conjugated protein in the lavage fluid, which was identified as serum albumin. Tandem mass spectrometry analysis of MDI-albumin revealed MDI conjugation occurs at a dilysine motif at Lys525, as well as at a glutamine-lysine motif at Lys414, in good agreement with previously published in vitro data on diisocyanate-conjugated serum albumin. |
The Influence of Diisocyanate Antigen Preparation Methodology on Monoclonal and Serum Antibody Recognition
Hagerman LM , Law BF , Bledsoe TA , Hettick JM , Kashon ML , Lemons AR , Wisnewski AV , Siegel PD . J Occup Environ Hyg 2016 13 (11) 829-39 Exposure to diisocyanates (dNCOs), such as methylene diphenyl diisocyanate (MDI) can cause occupational asthma (OA). Currently, lab tests for dNCO specific IgE are specific, but not sensitive, which limits their utility in diagnosing dNCO asthma. This may be due to variable preparation and poor characterization of the standard antigens utilized in these assays. The aim of this study was to produce and characterize a panel of antigens prepared using three different commonly employed methods and one novel method. The conjugates were examined for recognition by anti-MDI monoclonal antibodies (mAbs) in varying enzyme linked immunosorbant assay (ELISA) formats, extent of crosslinking, total amount of MDI, the sites of MDI conjugation, relative shape/charge, and reactivity with human serum with antibodies from sensitized, exposed workers. Results indicate that while there are minimal differences in the total amount of MDI conjugated, the extent of crosslinking, and the conjugation sites, there are significant differences in the recognition of differently prepared conjugates by mAbs. Native and denaturing polyacrylamide gel electrophoresis demonstrate differences in the mobility of different conjugates, indicative of structural changes that are likely important for antigenicity. While mAbs exhibited differential binding to different conjugates, polyclonal serum antibodies from MDI exposed workers exhibited equivalent binding to different conjugates by ELISA. While differences in the recognition of the different conjugates exist by mAb detection, differences in antigenicity could not be detected using human serum from MDI-sensitized individuals. Thus, although dNCO conjugate preparation can, depending on the immunoassay platform, influence binding of specific antibody clones, serologic detection of the dNCO-exposure-induced polyclonal antibody response may be less sensitive to these differences. |
Characterization and comparative analysis of 2,4-toluene diisocyanate and 1,6-hexamethylene diisocyanate haptenated human serum albumin and hemoglobin
Mhike M , Hettick JM , Chipinda I , Law BF , Bledsoe TA , Lemons AR , Nayak AP , Green BJ , Beezhold DH , Simoyi RH , Siegel PD . J Immunol Methods 2016 431 38-44 Diisocyanates (dNCOs) are low molecular weight chemical sensitizers that react with autologous proteins to produce neoantigens. dNCO-haptenated proteins have been used as immunogens for generation of dNCO-specific antibodies and as antigens to screen for dNCO-specific antibodies in exposed individuals. Detection of dNCO-specific antibodies in exposed individuals for diagnosis of dNCO asthma has been hampered by poor sensitivities of the assay methods in that specific IgE can only be detected in approximately 25% of the dNCO asthmatics. Apart from characterization of the conjugates used for these immunoassays, the choice of the carrier protein and the dNCO used are important parameters that can influence the detection of dNCO-specific antibodies. Human serum albumin (HSA) is the most common carrier protein used for detection of dNCO specific-IgE and -IgG but the immunogenicity and/or antigenicity of other proteins that may be modified by dNCO in vivo is not well documented. In the current study, 2,4-toluene diisocyanate (TDI) and 1,6-hexamethylene diisocyanate (HDI) were reacted with HSA and human hemoglobin (Hb) and the resultant adducts were characterized by (i) HPLC quantification of the diamine produced from acid hydrolysis of the adducts, (ii) 2,4,6-trinitrobenzene sulfonic acid (TNBS) assay to assess extent of cross-linking, (iii) electrophoretic migration in polyacrylamide gels to analyze intra- and inter-molecular cross-linking, and (iv) evaluation of antigenicity using a monoclonal antibody developed previously to TDI conjugated to Keyhole limpet hemocyanin (KLH). Concentration-dependent increases in the amount of dNCO bound to HDI and TDI, cross-linking, migration in gels, and antibody-binding were observed. TDI reactivity with both HSA and Hb was significantly higher than HDI. Hb-TDI antigenicity was approximately 30% that of HSA-TDI. In conclusion, this data suggests that both, the extent of haptenation as well as the degree of cross-linking differs between the two diisocyanate species studied, which may influence their relative immunogenicity and/or antigenicity. |
Exposures and cross-shift lung function declines in wildland firefighters
Gaughan DM , Piacitelli CA , Chen BT , Law BF , Virji MA , Edwards NT , Enright PL , Schwegler-Berry DE , Leonard SS , Wagner GR , Kobzik L , Kales SN , Hughes MD , Christiani DC , Siegel PD , Cox-Ganser JM , Hoover MD . J Occup Environ Hyg 2014 11 (9) 591-603 Respiratory problems are common among wildland firefighters. However, there are few studies directly linking occupational exposures to respiratory effects in this population. Our objective was to characterize wildland fire fighting occupational exposures and assess their associations with cross-shift changes in lung function. We studied 17 members of the Alpine Interagency Hotshot Crew with environmental sampling and pulmonary function testing during a large wildfire. We characterized particles by examining size distribution and mass concentration, and conducting elemental and morphological analyses. We examined associations between cross-shift lung function change and various analytes, including levoglucosan, an indicator of wood smoke from burning biomass. The levoglucosan component of the wildfire aerosol showed a predominantly bimodal size distribution: a coarse particle mode with a mass median aerodynamic diameter about 12 mum and a fine particle mode with a mass median aerodynamic diameter < 0.5 mum. Levoglucosan was found mainly in the respirable fraction and its concentration was higher for fire line construction operations than for mop-up operations. Larger cross-shift declines in forced expiratory volume in one second were associated with exposure to higher concentrations of respirable levoglucosan (p < 0.05). Paired analyses of real-time personal air sampling measurements indicated that higher carbon monoxide (CO) concentrations were correlated with higher particulate concentrations when examined by mean values, but not by individual data points. However, low CO concentrations did not provide reliable assurance of concomitantly low particulate concentrations. We conclude that inhalation of fine smoke particles is associated with acute lung function decline in some wildland firefighters. Based on short-term findings, it appears important to address possible long-term respiratory health issues for wildland firefighters. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resources: a file containing additional information on historical studies of wildland fire exposures, a file containing the daily-exposure-severity questionnaire completed by wildland firefighter participants at the end of each day, and a file containing additional details of the investigation of correlations between carbon monoxide concentrations and other measured exposure factors in the current study.]. |
Arterial stiffness, oxidative stress, and smoke exposure in wildland firefighters
Gaughan DM , Siegel PD , Hughes MD , Chang CY , Law BF , Campbell CR , Richards JC , Kales SF , Chertok M , Kobzik L , Nguyen PS , O'Donnell CR , Kiefer M , Wagner GR , Christiani DC . Am J Ind Med 2014 57 (7) 748-56 OBJECTIVES: To assess the association between exposure, oxidative stress, symptoms, and cardiorespiratory function in wildland firefighters. METHODS: We studied two Interagency Hotshot Crews with questionnaires, pulse wave analysis for arterial stiffness, spirometry, urinary 8-iso-prostaglandin F2alpha (8-isoprostane) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), and the smoke exposure marker (urinary levoglucosan). Arterial stiffness was assessed by examining levels of the aortic augmentation index, expressed as a percentage. An oxidative stress score comprising the average of z-scores created for 8-OHdG and 8-isoprostane was calculated. RESULTS: Mean augmentation index % was higher for participants with higher oxidative stress scores after adjusting for smoking status. Specifically for every one unit increase in oxidative stress score the augmentation index % increased 10.5% (95% CI: 2.5, 18.5%). Higher mean lower respiratory symptom score was associated with lower percent predicted forced expiratory volume in one second/forced vital capacity. CONCLUSIONS: Biomarkers of oxidative stress may serve as indicators of arterial stiffness in wildland firefighters. |
Concentrations and stability of methyl methacrylate, glutaraldehyde, formaldehyde and nickel sulfate in commercial patch test allergen preparations
Siegel PD , Fowler JF , Law BF , Warshaw EM , Taylor JS . Contact Dermatitis 2014 70 (5) 309-15 BACKGROUND: Epicutaneous patch tests are used to reproduce allergy and diagnose allergic contact dermatitis. Reliable allergen test preparations are required. OBJECTIVES: The purpose of the present study was to measure the actual concentrations of nickel(II) sulfate hexahydrate (NiSO4 ), methyl methacrylate, formaldehyde, and glutaraldehyde, and to compare them with the labelled concentrations, in commercial patch test allergen preparations found in dermatology clinics where patch testing is routinely performed. MATERIALS AND METHODS: The commercial in-date and out-of-date patch test allergen preparations concentrations of NiSO4 , methyl methacrylate, formaldehyde and glutaraldehyde from one to three participating clinics were analysed with chromatographic or wet chemical techniques. RESULTS: NiSO4 and formaldehyde concentrations were at or above the labelled concentrations; however, formaldehyde loss occurred with storage. NiSO4 particulate was uniformly distributed throughout the petrolatum. 'In-use' methyl methacrylate reagent syringes all contained ≤ 56% of the 2% label concentration, with no observable relationship with expiration date. Lower methyl methacrylate cocentrations were consistently measured at the syringe tip end, suggesting loss resulting from methyl methacrylate's volatility. The concentrations of glutaraldehyde patch test allergen preparations ranged from 27% to 45% of the labelled (1% in pet.) concentration, independently of expiration date. CONCLUSIONS: Some false-negative methyl methacrylate, formaldehyde or glutaraldehyde patch test results may be attributable to instability of the test preparations. |
A murine monoclonal antibody with broad specificity for occupationally relevant diisocyanates
Lemons AR , Siegel PD , Mhike M , Law BF , Hettick JM , Bledsoe TA , Nayak AP , Beezhold DH , Green BJ . J Occup Environ Hyg 2014 11 (2) 101-10 Diisocyanates (dNCOs) used in industrial applications are well known low molecular weight allergens. Occupational exposure is associated with adverse health outcomes including allergic sensitization and occupational asthma. In this study, we report the production and initial characterization of a dNCO-hapten specific murine IgM monoclonal antibody (mAb). Female BALB/c mice were immunized intraperitoneally with 25 mug of 4,4'-methylene diphenyl diisocyanate (MDI)-keyhole limpet hemocyanin. Following six biweekly booster immunizations, splenocytes were recovered and fused to Sp2/0-Ag14 murine myeloma cell line for hybridoma production. Hybridomas were then screened in a solid-phase indirect enzyme-linked immunosorbent assay (ELISA) against 40:1 4,4'-MDI- human serum albumin (HSA). mAb reactivity to dNCO-HSA conjugates and dNCO-HSA spiked human serum were characterized using a sandwich ELISA. One hybridoma produced a multimeric IgM mAb (15D4) that reacted with 4,4'-MDI-HSA. Sandwich ELISA analysis demonstrated comparable reactivity with other occupationally relevant dNCO-HSA adducts, including 2,4-toluene diisocyanate (TDI)-HSA, 2,6-TDI-HSA, and 1,6-hexamethylene diisocyanate (HDI)-HSA, but not other electrophilic chemical HSA conjugates. The limit of quantification (LOQ) of 4,4'-MDI-HSA, 2,4-TDI-HSA, 2,6-TDI-HSA, and 1,6-HDI-HSA sandwich ELISAs were 567.2, 172.7, 184.2, and 403.5 ng/mL (8.67, 2.60, 2.77, and 6.07 pmol/mL), respectively. In contrast, experiments using dNCO-supplemented human sera showed an increase in the detectable limit of the assay. A mAb has been produced that has potential utility for detecting mixed diisocyanate exposures in occupational environments. The mAb may have additional utility in the standardization of specific IgE detection immunoassays as well as chromatographic-mass spectrometric methods to enrich dNCO adducted HSA in the plasma of occupationally exposed workers. |
Pyridoxylamine reactivity kinetics as an amine based nucleophile for screening electrophilic dermal sensitizers
Chipinda I , Mbiya W , Adigun RA , Morakinyo MK , Law BF , Simoyi RH , Siegel PD . Toxicology 2013 315C 102-109 Chemical allergens bind directly, or after metabolic or abiotic activation, to endogenous proteins to become allergenic. Assessment of this initial binding has been suggested as a target for development of assays to screen chemicals for their allergenic potential. Recently we reported a nitrobenzenethiol (NBT) based method for screening thiol reactive skin sensitizers, however, amine selective sensitizers are not detected by this assay. In the present study we describe an amine (pyridoxylamine (PDA)) based kinetic assay to complement the NBT assay for identification of amine-selective and non-selective skin sensitizers. UV-Vis spectrophotometry and fluorescence were used to measure PDA reactivity for 57 chemicals including anhydrides, aldehydes, and quinones where reaction rates ranged from 116 to 6.2x10-6M-1s-1 for extreme to weak sensitizers, respectively. No reactivity towards PDA was observed with the thiol-selective sensitizers, non-sensitizers and prohaptens. The PDA rate constants correlated significantly with their respective murine local lymph node assay (LLNA) threshold EC3 values (R2=0.76). The use of PDA serves as a simple, inexpensive amine based method that shows promise as a preliminary screening tool for electrophilic, amine-selective skin sensitizers. |
Pulmonary immune responses to Aspergillus fumigatus in an immunocompetent mouse model of repeated exposures
Buskirk AD , Templeton SP , Nayak AP , Hettick JM , Law BF , Green BJ , Beezhold DH . J Immunotoxicol 2013 11 (2) 180-9 Aspergillus fumigatus is a filamentous fungus that produces abundant pigmented conidia. Several fungal components have been identified as virulence factors, including melanin; however, the impact of these factors in a repeated exposure model resembling natural environmental exposures remains unknown. This study examined the role of fungal melanin in the stimulation of pulmonary immune responses using immunocompetent BALB/c mice in a multiple exposure model. It compared conidia from wild-type A. fumigatus to two melanin mutants of the same strain, Deltaarp2 (tan) or Deltaalb1 (white). Mass spectrometry-based analysis of conidial extracts demonstrated that there was little difference in the protein fingerprint profiles between the three strains. Field emission scanning electron microscopy demonstrated that the immunologically inert Rodlet A layer remained intact in melanin-deficient conidia. Thus, the primary difference between the strains was the extent of melanization. Histopathology indicated that each A. fumigatus strain induced lung inflammation, regardless of the extent of melanization. In mice exposed to Deltaalb1 conidia, an increase in airway eosinophils and a decrease in neutrophils and CD8+ IL-17+ (Tc17) cells were observed. Additionally, it was shown that melanin mutant conidia were more rapidly cleared from the lungs than wild-type conidia. These data suggest that the presence of fungal melanin may modulate the pulmonary immune response in a mouse model of repeated exposures to A. fumigatus conidia. |
Thiurams in shoe contact dermatitis - a case series
Munk R , Sasseville D , Siegel PD , Law BF , Moreau L . Contact Dermatitis 2013 68 (3) 185-7 We present four patients who developed allergic contact dermatitis on their feet after wearing Keds® Canvas sneakers. All patients underwent patch testing with the North American Contact Dermatitis Group (NACDG) Baseline series (Chemotechnique Diagnostics AB, Vellinge, Sweden), and various other allergen trays, depending on the clinical scenario, including a glues and adhesives series (Chemotechnique Diagnostics AB), a shoe series (Chemotechnique Diagnostics AB), and a textile tray (Chemotechnique Diagnostics AB). All 4 patients developed positive reactions to the thiuram mix, as well as to pieces of their shoes (Fig. 1). We initially believed that thiuram accelerators were used in this type of rubber-based canvas shoe. However, subsequent chemical analysis failed to identify thiurams in two different pairs of shoes. Table 1 summarizes the individual characteristics and patch test results of each patient. |
Safety and chemical exposure evaluation at a small biodiesel production facility
Law BF , Pearce T , Siegel PD . J Occup Environ Hyg 2011 8 (7) 68-72 Biodiesel is a renewable fuel produced when agricultural feedstocks such as vegetable oils, rendered animal fats, and used cooking oils are reacted with alcohol in the presence of a catalyst to form fatty acid esters, glycerin, and soap in a process known as transesterification. Because of economics and process considerations, methanol is the most commonly used alcohol in the transesterification process producing fatty acid methyl esters.( Citation1 ) Potential hazards of biodiesel production include (1) use of large quantities of methanol, (2) use of caustic chemicals as catalysts, (3) physical hazards, and (4) potential exposure to aldehydes. | The biodiesel industry recognizes its most significant hazard as methanol. The properties of methanol, both physical and chemical, make it a particularly hazardous chemical. Methanol is highly flammable, and exposures can cause a wide range of deleterious health effects. It is easily absorbed by all routes of exposure. Methanol is metabolized to formaldehyde that is then converted to formic acid, which can accumulate in the human body. Methanol toxicity is mediated, in large part, by the formic acid metabolite. Studies have shown that short-term inhalation exposure to 200 ppm methanol results in blood methanol concentrations of less than 10 mg/L with no observed increase in blood formic acid concentration.( Citation2 ) Acute methanol toxicity includes visual disturbances leading to blindness, mild dermal irritation, dizziness, giddiness, permanent motor dysfunction. and possibly death.( Citation3 – Citation5 ) Chronic exposure to methanol may result in headache, dizziness, giddiness, insomnia, nausea, gastric disturbances, conjunctivitis, visual disturbances, and blindness.( Citation3 ) The Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) and the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit (REL) for methanol is 200 ppm time-weighted average (TWA). The short-term exposure limit (STEL) for methanol is 250 ppm; the concentration that is immediately dangerous to life and health (IDLH) is 6000 ppm.( Citation6 ) |
Fungal pigments inhibit the MALDI-TOF mass spectrometry analysis of darkly pigmented fungi
Buskirk AD , Hettick JM , Chipinda I , Law BF , Siegel PD , Slaven JE , Green BJ , Beezhold DH . Anal Biochem 2010 411 (1) 122-8 Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been used to discriminate monilaceous fungal species, however, darkly pigmented fungi yield poor fingerprint mass spectra that contain few peaks of low relative abundance. In this study, the effect of dark fungal pigments on the observed MALDI mass spectra was investigated. Peptide and protein samples containing varying concentrations of synthetic melanin or fungal pigments extracted from Aspergillus niger were analyzed by MALDI-TOF and MALDI-qTOF MS. Signal suppression was observed in samples containing greater than 25 ng/muL pigment. Microscopic examination of the MALDI sample deposit was usually heterogeneous, with regions of high pigment concentration appearing black. Acquisition of MALDI mass spectra from these darkly pigmented regions of the sample deposit yielded poor or no [M+H](+) ion signal. In contrast, non-pigmented regions within the sample deposit and hyphal negative control extracts of A. niger were not inhibited. This study demonstrated that dark fungal pigments inhibited the desorption/ionization process during MALDI-MS; however these fungi may be successfully analyzed by MALDI-TOF MS when culture methods that suppress pigment expression are used. Addition of tricyclazole to the fungal growth media blocks fungal melanin synthesis and results in less-melanized fungi that may be analyzed by MALDI-TOF MS. |
Reservations concerning second-hand fentanyl exposure in the operating room
Law BF , Hettick JM , Hornsby-Myers J , Siegel PD . J Addict Dis 2010 29 (3) 282-3 We are aware of the controversy that Dr. Gold's report of trace levels of fentanyl and propofol in the air of surgical rooms has evoked.Citation1 , Citation2 , Citation3 , Citation4 Drug dependence among surgical and anesthesiology staff is a serious and complex issue, and we acknowledge the potential for generation of bioaerosol containing narcotics during surgery. Our study was an examination of room air during cardiovascular surgeries in a local hospital to quantify the level of “second hand” fentanyl,Citation 5 a similar setting to that previously reported.Citation 6 | Our findings are relevant to fentanyl only; we did not study or attempt to measure propofol. Our manuscript carefully detailed our sampling and analytical methodologies. We sampled an approximate 780-fold greater air volume and used instrumentation of equal sensitivity and better specificity to that reported by Dr. Gold. We are confident that if fentanyl-containing bioaerosol were present in the vicinity of the anesthesiology station at levels previously reported,Citation 5 we would have been able to quantify it. |
Disproportionated rosin dehydroabietic acid in neoprene surgical gloves
Siegel PD , Law BF , Fowler Jr JF , Fowler LM . Dermatitis 2010 21 (3) 157-9 BACKGROUND: Allergic contact dermatitis (ACD) is a well-recognized immune-mediated disease often associated with the use of vulcanization accelerator-containing latex and nitrile gloves. Potential contact allergens in neoprene (polychloroisoprene, polychloroprene) gloves have not been reported. OBJECTIVE: The objective was to analyze extracts of neoprene surgical and examination gloves for potential contact allergens. METHODS: Four different brands of neoprene-type gloves were purchased, and dichloromethane extracts were derivatized and assayed by gas chromatographic mass spectrometry. A latex surgical glove was used as a negative control. RESULTS: Chemical species consistent with the composition of disproportionated rosin (dehydroabietic acid [DHA], didehydroabietic acid, and other pimaric or isopimaric species) were identified in dichloromethane extracts of neoprene gloves. Levels of DHA, a type IV prohapten that can be air oxidized to an active allergen, ranged from 7 to 31 mg/g of glove. A leaching study of DHA was conducted, and small amounts of DHA leached from the glove materials into artificial sweat. DHA oxidation products were not observed in any of the gloves assayed. CONCLUSION: DHA exposure may occur from neoprene-type glove use, although a potential association with glove ACD has not been established. |
Allergen content of patient problem and nonproblem gloves: relationship to allergen-specific patch-test findings
Siegel PD , Fowler Jr JF , Storrs FJ , Sasseville D , Pratt M , Bledsoe TA , Law BF , Beezhold D , Zug K , Fowler LM . Dermatitis 2010 21 (2) 77-83 BACKGROUND: Identification of putative contact allergen and source material is often done by a combination of patch testing and manufacturer-supplied product information. The accuracy of the identification of allergen-source material and level of allergen in that allergen-source material is not known. OBJECTIVE: The objectives of the study were to survey the chemical allergen content of glove allergic contact dermatitis (ACD) patient-identified problem and nonproblem gloves and to evaluate the ability of the patient to discriminate between problem and nonproblem gloves. METHODS: Gloves from patch-tested rubber allergen-positive ACD patients were analyzed for species and amount of rubber allergen. RESULTS: Approximately half the subjects were able to correctly identify their problem and nonproblem gloves. Correct association of a glove with ACD was directly related to patch-test reaction severity and inversely related to the number of glove brands being used by the patient. Of note, thiurams were not detected in any of the gloves examined. CONCLUSIONS: Although patch testing is invaluable in identifying individual allergen sensitivities, the identification of the ACD-causative specific chemical allergen and source material remains problematic. All glove brands used within days prior to and during an ACD episode should be considered potential sources of the contact allergen. |
Analytical methodology and assessment of potential second-hand exposure to fentanyl in the hospital surgical setting
Law BF , Hettick JM , Hornsby Myers J , Siegel PD . J Addict Dis 2010 29 (1) 51-58 Second-hand exposure to aerosols containing fentanyl and other opiates during surgical procedures has been implicated as possibly contributing to maintenance of addiction among medical professionals, specifically anesthesiologists. This article outlines a pilot study that was conducted to verify a reported finding fentanyl in the air of operating suites. Environmental fentanyl air sampling and analysis methods were developed and evaluated for this study. Multiple sampling media and extraction solvents were evaluated for trace fentanyl air sampling. Non-specific binding losses were reduced by using silanized binder-free glass fiber sampling media with subsequent methanol extraction. Filtration air samples were then collected in surgical suites during the entire operation time from two cardiovascular surgical procedures. Both surgical procedures were conducted at the same hospital but on different days. Samples were extracted and analyzed by high-performance liquid chromatography/tandem mass spectrometry using a capillary high-performance liquid chromatography coupled to a quadrupole time-of-flight mass spectrometer. The total air volume collected per surgery was 290 to 300 L at a rate of 1 LPM giving an limit of quantification for fentanyl of 57 pg/m3 air (17 pg/filter). No fentanyl was detected in the air during cardiovascular surgical operations from either surgical suite. |
Coal dust alters beta-naphthoflavone-induced aryl hydrocarbon receptor nuclear translocation in alveolar type II cells
Ghanem MM , Battelli LA , Law BF , Castranova V , Kashon ML , Nath J , Hubbs AF . Part Fibre Toxicol 2009 6 21 BACKGROUND: Many polycyclic aromatic hydrocarbons (PAHs) can cause DNA adducts and initiate carcinogenesis. Mixed exposures to coal dust (CD) and PAHs are common in occupational settings. In the CD and PAH-exposed lung, CD increases apoptosis and causes alveolar type II (AT-II) cell hyperplasia but reduces CYP1A1 induction. Inflammation, but not apoptosis, appears etiologically associated with reduced CYP1A1 induction in this mixed exposure model. Many AT-II cells in the CD-exposed lungs have no detectable CYP1A1 induction after PAH exposure. Although AT-II cells are a small subfraction of lung cells, they are believed to be a potential progenitor cell for some lung cancers. Because CYP1A1 is induced via ligand-mediated nuclear translocation of the aryl hydrocarbon receptor (AhR), we investigated the effect of CD on PAH-induced nuclear translocation of AhR in AT-II cells isolated from in vivo-exposed rats. Rats received CD or vehicle (saline) by intratracheal (IT) instillation. Three days before sacrifice, half of the rats in each group started daily intraperitoneal injections of the PAH, beta-naphthoflavone (BNF). RESULTS: Fourteen days after IT CD exposure and 1 day after the last intraperitoneal BNF injection, AhR immunofluorescence indicated that proportional AhR nuclear expression and the percentage of cells with nuclear AhR were significantly increased in rats receiving IT saline and BNF injections compared to vehicle controls. However, in CD-exposed rats, BNF did not significantly alter the nuclear localization or cytosolic expression of AhR compared to rats receiving CD and oil. CONCLUSION: Our findings suggest that during particle and PAH mixed exposures, CD alters the BNF-induced nuclear translocation of AhR in AT-II cells. This provides an explanation for the modification of CYP1A1 induction in these cells. Thus, this study suggests that mechanisms for reduced PAH-induced CYP1A1 activity in the CD exposed lung include not only the effects of inflammation on the lung as a whole, but also reduced PAH-associated nuclear translocation of AhR in an expanded population of AT-II cells. |
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