Modeling PFAS Fate and Transport in Groundwater, with and Without Precursor Transformation.

Groundwater professionals require tools to evaluate a variety of technical issues related to per- and polyfluoroalkyl substances (PFAS). These include the potential impact of PFAS precursors on groundwater plumes of perfluoroalkyl acids (PFAAs). Numerical modeling results show that, by adjusting the mass loading rate, source zones with or without a precursor can produce similar PFAA plumes.

The impact of precursors on aquatic exposure assessment for PFAS: Insights from bioaccumulation modeling.

Risk assessment for per- and polyfluoroalkyl substances (PFAS) is complicated by the fact that PFAS include several thousand compounds. Although new analytical methods have increased the number that can be identified in environmental samples, a significant fraction of them remain uncharacterized. Perfluorooctane sulfonate (PFOS) is the PFAS compound of primary interest when evaluating risks to humans and wildlife owing to the consumption of aquatic organisms.

Virtual reality exposure therapy in the treatment of fear of flying: a case report.

The efficacy of virtual reality (VR) exposure therapy was examined for the fear of flying. Virtual reality exposure involved six sessions of graded exposure to flying in a virtual airplane. The specific contribution of anxiety management techniques (AMT) and the VR exposure was examined in a single case design.

Effectiveness of computer-generated (virtual reality) graded exposure in the treatment of acrophobia.

Objective: The authors' goal was to examine the efficacy of computer-generated (virtual reality) graded exposure in the treatment of acrophobia (fear of heights).

Method: Twenty college students with acrophobia were randomly assigned to virtual reality graded exposure treatment (N = 12) or to a waiting-list comparison group (N = 8). Seventeen students completed the study.

Neurotoxic properties of musk ambrette.

Musk ambrette (2,6-dinitro-3-methoxy-4-tert-butyltoluene), a nitro-musk compound widely used as a fixative in fragrance formulations and found to a lesser degree in flavor compositions, produces hindlimb weakness when administered in the diet or applied to skin of rats for periods up to 12 weeks. Underlying neuropathologic changes consist of primary demyelination and distal axonal degeneration in selected regions of the central and peripheral nervous system. Murine neurological disease induced by musk ambrette occurs at doses well above estimated maximum daily human exposure.

Vascular recovery following hemorrhage in the dogfish shark Squalus acanthias.

Cardiovascular regulatory systems were examined in the dogfish shark after hemorrhage of 1% of body weight. An immediate 45% decrease in mean dorsal aortic pressure and delayed increases in plasma epinephrine concentration and plasma norepinephrine concentration were noted. During the recovery period following hemorrhage, the catecholamine levels peaked (epinephrine 203% of control, norepinephrine 148% of control) and then returned toward control values.

Effect of ganglionic blockade on catecholamine secretion in exercised dogfish.

A brief bout of vigorous exercise results in significant increases in plasma epinephrine (E) and norepinephrine (NE) in the dogfish, Squalus acanthias. Since the presence of a functioning sympathetic nervous system in dogfish is in doubt, experiments were undertaken to show whether or not exercise-induced catecholamine (CA) secretion is under autonomic neurogenic control. Changes in plasma E and NE in a control group of exercised fish were compared with changes in fish exercised while under the influence of ganglionic blockade.

Synthesis of nonmammalian angiotensins and their comparative pressor properties in dogfish shark, domestic chicken, and rat.

To understand how vertebrates utilize angiotensins during evolutionary development, we undertook studies to synthesize and/or characterize angiotensin-like peptides from nonmammalian species. The present paper describes the synthesis of [Asp1,Val5,Asn9] angiotensin I (bull frog, Rana catesbeiana) (I), [Asn1,Val5,His9] angiotensin I (Japanese goosefish, Lophius litulon) (II), [Asn1, Val5,Asn9] angiotensin I (chum salmon, Oncorhynchus keta) (III), and [Asn1, Val5,Tyr9] angiotensin I (related to native angiotensin in snake, Elaphe climocophora (IV). Pressor properties of these peptides were compared with the peptides isolated from other species and related synthetic analogs in one representative species from three distinct classes of vertebrates: 1) elasmobranchs: spiny dogfish shark; 2) birds: domestic chicken; and 3) mammals: rat.

Dual mechanism for catecholamine secretion in the dogfish shark Squalus acanthias.

Both 1,1-dimethyl-4-phenylpiperazinium iodide, a ganglionic stimulating drug (DMPP), and potassium ion (K+) cause a pressor response when injected into Squalus acanthias, an elasmobranch. The pressor responses are due to increased secretion of epinephrine and norepinephrine. The pressor response to DMPP can be blocked by prior infusion of hexamethonium, a ganglionic blocking drug.

Evolution of angiotensin II-induced catecholamine release.

The interaction between angiotensin II (ANG II) and catecholamines was examined in nonmammalian vertebrates. ANG II challenge caused a significant pressor response in representatives of the seven vertebrate classes. Additionally, plasma levels of both epinephrine and norepinephrine increased following intravascular ANG II injection in the conscious lumpfish, bullfrog, and turtle, and the anesthetized chicken.

Catecholamine release and blood pressure changes induced by exercise in dogfish.

Plasma norepinephrine (NE), epinephrine (E), and potassium (K+) were measured before, during a 3-min bout of exercise, and at intervals after exercise in Squalus acanthias. The dorsal aortic pressure response following 1 min of exercise was observed in another series of experiments. Plasma E, NE, and K+ increased significantly and progressively during the exercise period and for 2 min after exercise.

Dogfish pressor response to potassium blocked by magnesium and phentolamine.

In vivo infusion of MgCl2 blocks the dogfish pressor response to K+. This action of Mg2+ was contrasted to phentolamine in in vivo and in vitro experiments. Mg2+ blocks the spontaneous release of catecholamines from dogfish chromaffin tissue but does not alter the norepinephrine-induced contraction of the isolated dogfish artery.

Effect of angiotensin II on vascular resistance in whole-body perfused dogfish.

1. The effect of angiotensin II (AII), norepinephrine (NE), epinephrine (E) and isoproterenol (ISO) was observed on the branchial and systemic circulations in a whole-body-pump perfused dogfish preparation. 2.

Systemic arterial pressor responses induced by potassium in dogfish, Squalus acanthias.

Intravascular injection of small doses of potassium (0.025-0.5 meq) into dogfish results in dose-related dorsal aortic pressor responses.