Characterization of per- and polyfluoroalkyl substances on fire suppression system piping and optimization of removal methods.

Fire suppression systems are known to be impacted with residual, entrained per- and polyfluoroalkyl substances (PFASs) because of historical use of aqueous film forming foam (AFFF) and fluoroprotein foam. Amphiphilic PFASs aggregate at liquid:solid interfaces creating a hydrophobic layer which reduces the effectiveness of water to remove PFAS from layered surfaces. When fire suppression systems are transitioned to fluorine free foam (F3) without appropriate cleaning, residual PFASs associated with the surfaces of the fire suppression system can contaminate the replacement F3. Release of residual PFASs from fire suppression systems into F3 has been documented; however, little is known about the residual PFASs associated with the surfaces of the fire suppression systems. More information is needed to develop methods to appropriately remove PFASs from fire suppression systems to prevent costly and inefficient foam transitioning and preserve the PFAS-free benefit of F3. The objective of this work was to evaluate the distribution and composition of PFASs on hangar piping exposed to PFAS-containing firefighting foam for a prolonged period. Two assessment methods were used: 1) extractions with methanol, water, and a proprietary aqueous organic solvent (Fluoro Fighter™); and 2) direct imaging methods of the surface. Extractions were analyzed with mass spectrometry and combustion ion chromatography. Results indicate pipe in contact with PFAS-containing firefighting foam can amass approximately 10 µg/cm2 of surface-associated PFAS residual following decades of exposure. Fluoro Fighter demonstrated higher PFAS removal per surface area of pipe than methanol (p = 0.007) or water extraction (p < 0.0001). Scanning electron microscope (SEM) images of the hangar piping reveal deposits suspected to be self-assembled PFAS layers, as evidenced by examination of pipe surfaces using X-ray photoelectron spectroscopy (XPS), which revealed atomic fluorine on the surface of the pipe.

Safety and efficacy of prednisone versus placebo in short-term prevention of episodic cluster headache: a multicentre, double-blind, randomised controlled trial.

BACKGROUND: Prednisone is commonly used for initial short-term therapy of episodic cluster headaches before preventive medication such as verapamil becomes effective, but this strategy has not been tested in large randomised trials. We aimed to access the safety and efficacy of this treatment approach. METHODS: This study was a multicentre, randomised, double-blind, placebo-controlled trial done in ten specialised headache centres in Germany. Patients with episodic cluster headaches who were aged between 18 and 65 years and within a current pain episode for not more than 30 days, received 100 mg oral prednisone for 5 days followed by tapering of 20 mg every 3 days, or matching placebo (17 days total exposure). All patients received oral verapamil for long-term prevention, starting with 40 mg three times daily and increasing to 120 mg three times daily by day 19; patients then continued with verapamil 120 mg throughout the study. Randomisation was computer-generated at a 1:1 ratio by use of an interactive web-response system, with stratification according to age, sex, and participating site. Participants, investigators, and those assessing outcomes were unaware of treatment allocation. The primary endpoint was the mean number of attacks within the first week of treatment with prednisone compared with placebo. An attack was defined as a unilateral headache with moderate-to-severe intensity of at least five on a numerical rating scale. All efficacy and safety analyses were done in the modified intention-to-treat (mITT) population, which consisted of all patients who had been randomly assigned to a trial group and received at least one dose of prednisone or placebo. The study was stopped early due to slow recruitment and expired funding. The study was registered with EudraCT (2011-006204-13) and with the German Clinical Trials Register (DRKS00004716). FINDINGS: Between April 5, 2013, and Jan 11, 2018, 118 patients were enrolled in the study. Two patients dropped out immediately and 116 patients were randomly assigned (57 patients to prednisone and 59 patients to placebo); 109 patients were included in the mITT analysis (53 patients assigned to prednisone and 56 patients assigned to placebo). Participants in the prednisone group had a mean of 7·1 (SD 6·5) attacks within the first week compared with 9·5 (6·0) attacks in the placebo group (difference -2·4 attacks, 95% CI -4·8 to -0·03; p=0·002). Two serious adverse events occurred, both in the placebo group (inguinal hernia and severe deterioration of cluster headache). A total of 270 adverse events were observed: in the prednisone group, 37 (71%) of 52 patients reported 135 adverse events (most common were headache, palpitations, dizziness, and nausea) and in the placebo group, 39 (71%) of 55 patients had 135 adverse events (most common were nausea, dizziness, and headache). INTERPRETATION: Oral prednisone was an effective short-term preventive therapy in our population of patients with episodic cluster headache. Our findings support the use of prednisone as a first-line treatment in parallel to the up-titration of verapamil, although the efficacy of prednisone alongside other long-term prevention requires additional investigation. FUNDING: German Federal Ministry for Education and Research.

Long-range inhibitory mechanisms in the visual system are impaired in migraine sufferers.

BACKGROUND: After viewing dynamic noise surrounding a homogeneous grey patch (artificial scotoma), observers perceive a prolonged twinkling-noise after-image within the unstimulated area. It has been suggested that noise-stimulated neurons induce a long-range inhibition in neurons within the artificial scotoma, which generates a rebound signal perceived as twinkling noise following noise termination. We used this paradigm to test whether migraineurs have enhanced excitability or weakened inhibition. METHODS: Twinkling-noise duration was measured in 13 headache-free volunteers, 13 migraineurs with aura and 13 migraineurs without aura. RESULTS: The durations of the after-image were significantly shorter for both migraine groups compared to controls. DISCUSSION: Enhanced excitation of noise-activated neurons in migraineurs would produce stronger rebound activity and longer after-image durations, while weakened inhibitory mechanisms would diminish the rebound activity and shorten the after-image durations compared to control subjects. The results suggest that cortical inhibitory mechanisms might be impaired in migraineurs with and without aura.