Inhalation of butter flavoring by workers in the microwave popcorn industry may result in “popcorn workers' lung.” In previous in vivo studies rats exposed for 6 h to vapor from the flavoring agents, diacetyl and 2,3-pentanedione, acquired flavoring concentration-dependent damage of the upper airway epithelium and airway hyporeactivity to inhaled methacholine. Because ion transport is essential for lung fluid balance, we hypothesized that alterations in ion transport may be an early manifestation of butter flavoring-induced toxicity. We developed a system to expose cultured human bronchial/tracheal epithelial cells (NHBEs) to flavoring vapors. NHBEs were exposed for 6 h to diacetyl or 2,3-pentanedione vapors (25 or ≥ 60 ppm) and the effects on short circuit current and transepithelial resistance (Rt) were measured. Immediately after exposure to 25 ppm both flavorings reduced Na+ transport, without affecting Cl− transport or Na+,K+-pump activity. Rt was unaffected. Na+ transport recovered 18 h after exposure. Concentrations (100–360 ppm) of diacetyl and 2,3-pentanedione reported earlier to give rise in vivo to epithelial damage, and 60 ppm, caused death of NHBEs 0 h post-exposure. Analysis of the basolateral medium indicated that NHBEs metabolize diacetyl and 2,3-pentanedione to acetoin and 2-hydroxy-3-pentanone, respectively. The results indicate that ion transport is inhibited transiently in airway epithelial cells by lower concentrations of the flavorings than those that result in morphological changes of the cells in vivo or in vitro.

Abstract This study investigated the in vivo pulmonary toxicity of inhaled multi-walled carbon nanotubes (MWCNT). Mice-inhaled aerosolized MWCNT (10 mg/m3, 5 h/day) for 2, 4, 8 or 12 days. MWCNT lung burden was linearly related to exposure duration. MWCNT-induced pulmonary inflammation was assessed by determining whole lung lavage (WLL) polymorphonuclear leukocytes (PMN). Lung cytotoxicity was assessed by WLL fluid LDH activities. WLL fluid albumin concentrations were determined as a marker of alveolar air–blood barrier integrity. These parameters significantly increased in MWCNT-exposed mice versus controls and were dose-dependent. Histopathologic alterations identified in the lung included (1) bronciolocentric inflammation, (2) bronchiolar epithelial hyperplasia and hypertrophy, (3) fibrosis, (4) vascular changes and (5) rare pleural penetration. MWCNT translocated to the lymph node where the deep paracortex was expanded after 8 or 12 days. Acute inhalation of MWCNT induced dose-dependent pulmonary inflammation and damage with rapid development of pulmonary fibrosis, and also demonstrated that MWCNT can reach the pleura after inhalation exposure.

Flavorings-related lung disease is a potentially disabling disease of food industry workers associated with exposure to the alpha-diketone butter flavoring, diacetyl (2,3-butanedione). To investigate the hypothesis that another a-diketone flavoring, 2,3-pentanedione, would cause airway damage, rats that inhaled air, 2,3-pentanedione (112, 241, 318, or 354 ppm), or diacetyl (240 ppm) for 6 hours were sacrificed the following day. Rats inhaling 2,3-pentanedione developed necrotizing rhinitis, tracheitis, and bronchitis comparable to diacetyl-induced injury. To investigate delayed toxicity, additional rats inhaled 318 (range, 317.9-318.9) ppm 2,3-pentanedione for 6 hours and were sacrificed 0 to 2, 12 to 14, or 18 to 20 hours after exposure. Respiratory epithelial injury in the upper nose involved both apoptosis and necrosis, which progressed through 12 to 14 hours after exposure. Olfactory neuroepithelial injury included loss of olfactory neurons that showed reduced expression of the 2,3-pentanedione metabolizing enzyme, dicarbonyl/L-xylulose reductase, relative to sustentacular cells. Caspase 3 activation occasionally involved olfactory nerve bundles that synapse in the olfactory bulb (OB). An additional group of rats inhaling 270 ppm 2,3-pentanedione for 6 hours 41 minutes showed increased expression of IL-6 and nitric oxide synthase-2 and decreased expression of vascular endothelial growth factor A in the OB, striatum, hippocampus, and cerebellum using real-time PCR. Claudin-1 expression increased in the OB and striatum. We conclude that 2,3-pentanedione is a respiratory hazard that can also alter gene expression in the brain. (Am J Pathol 2012, 181:829-844; http://dx.doi.org/10.1016/j.ajpath.2012.05.021)

Animal technicians reported a 16-weekold female B6;129S2-Tnfsf5 tm1Imx mouse for a primary complaint of cachexia.Clinical signs included lethargy, trembling, low body temperature, anorexia, and weight loss.The animal's body weight was less than 14 g.We subsequently euthanized the mouse by CO 2 administration and submitted it for necropsy.After receiving this mouse from the supplier (Jackson Laboratories, Bar Harbor, ME), we had housed it at a barrier facility in an individually ventilated polycarbonate microisolator cage (Thoren Caging Systems, Inc., Hazleton, PA).Husbandry procedures within the barrier facility included autoclaving of the microisolator cage after washing, supplying autoclaved bedding (ALPHA-dri, Shepherd, Watertown, TN) and autoclaved water bottles, and allowing ad libitum access to water and irradiated feed (7913; Harlan Teklad, Madison, WI).The animal was on study and was receiving intraperitoneal injections of corn oil.The animal technicians also reported that a cagemate of this animal was showing poor weight gain.We provide mice that become lethargic or cachexic during a study with Transgenic Dough Diet (Bio-Serv, Frenchtown, NJ) ad libitum.HEPA-filtered air at 15 air changes per hour supplied the room housing the mice; the cage system (Thoren) moved room air through a HEPA filter into the animal cages, and cage air pressure was positive with respect to the room.We monitored the specific pathogen-free status of the barrier facility by quarterly necropsy and comprehensive serology of sentinel animals exposed to used bedding, feed, and water bottles.Surveillance mice were negative by culture for murine bacterial pathogens and negative for Helicobacter spp.by PCR; we found no helminth or protozoal parasites in surveillance mice.Gross necropsy of the cachectic female B6;129S2-Tnfsf5 tm1Imx mouse showed minimal contents to be present in the gastrointestinal tract and scant, hard feces present in the colon.Multiple tissue samples were fixed in Prefer (Anatech Ltd., Battle Creek, MI), a formalin-free fixative of glyoxal, in a buffered mixture of water and ethanol.We then submitted tissues for histopathological examination.What do you expect the results of the histopathological examination will be?What do you think caused this mouse to become cachexic?21