Michael Parsons - Academia.edu (original) (raw)

Papers by Michael Parsons

Studies in Art Education, 2000

Australian Aboriginal Studies, Sep 22, 2002

Abstract: The nineteenth century Aboriginal corroboree performed for non-Indigenous settler audie... more Abstract: The nineteenth century Aboriginal corroboree performed for non-Indigenous settler audiences was Australia's pre-eminent prototypical Indigenous cultural tourism product. Options for the development of this product by both Aborigines and settlers were fashioned by ...

11th International Conference on Environmental Remediation and Radioactive Waste Management, Parts A and B, 2007

This study involved challenging nuclear grade high-efficiency particulate air (HEPA) filters unde... more This study involved challenging nuclear grade high-efficiency particulate air (HEPA) filters under a variety of conditions that can arise in Department of Energy (DOE) applications such as: low or high RH, controlled and uncontrolled challenge, and filters with physically damaged media or seals (i.e., leaks). Reported findings correlate filter function as measured by traditional differential pressure techniques in comparison with

Neurotoxicology and Teratology, 2015

Pyridostigmine bromide (PB) is an FDA-approved drug for the treatment of myasthenia gravis and a ... more Pyridostigmine bromide (PB) is an FDA-approved drug for the treatment of myasthenia gravis and a prophylactic pre-treatment for organophosphate nerve agent poisoning. Current methods for evaluating nerve agent treatments include enzymatic studies and mammalian models. Rapid whole animal screening tools for assessing the effects of nerve agent pre-treatment and post-exposure drugs represent an underdeveloped area of research. We used zebrafish as a model for acute and chronic developmental exposure to PB and two related carbamate acetylcholinesterase (AChE) inhibitors, neostigmine bromide (NB) and physostigmine (PS). Lethal doses and gross morphological phenotypes resulting from exposure to sub-lethal doses of these compounds were determined. Quantitative analyses of motility impairment and AChE enzyme inhibition were used to determine optimal dosing conditions for evaluation of the effects of carbamate exposures on neuronal development; ~50% impairment of response to startle stimuli and &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;50% inhibition of AChE activity were observed at 80mMPB, 20mM NB and 0.1mM PS. PB induced stunted somite length, but no other phenotypic effects were observed. In contrast, NB and PS induced more severe phenotypic morphological defects than PB as well as neurite outgrowth mislocalization. Additionally, NB induced mislocalization of nicotinic acetylcholine receptors, resulting in impaired synapse formation. Taken together, these data suggest that altered patterns of neuronal connectivity contribute to the developmental neurotoxicity of carbamates and demonstrate the utility of the zebrafish model for distinguishing subtle structure-based differential effects of AChE inhibitors, which include nerve agents, pesticides and drugs.

Journal of medicinal chemistry, Jan 4, 1992

Previously, gastric (H+/K+)-ATPase inhibitors such as 2 have been prepared as analogues of 1a on ... more Previously, gastric (H+/K+)-ATPase inhibitors such as 2 have been prepared as analogues of 1a on the presumption that the 3-carbethoxy substituent plays a key role in establishing the orientation of the 4-arylamino group. In this paper we explore further the contribution made to activity by the quinoline 3-substituent. We show that, for compounds bearing such a substituent, only a particular combination of properties provides high activity, both in vitro and as inhibitors of gastric acid secretion in vivo. The ability of the substituent to affect activity by restricting rotation about the Cquin-N bond through a combination of both a pi-electron withdrawal and hydrogen bonding is supported by the current study. However, high activity is only achieved if the effect of this group on the quinoline pK(a) is kept to a minimum. 3-Acyl substituents provide an optimum combination of electronic properties. From this series, compound 17c (SK&F 96067) was shown to be a potent inhibitor of hista...

Journal of Medicinal Chemistry, 1975

Histamine exists predominantly as the NT-H tautomer of the monocation (IIa) at a physiological pH... more Histamine exists predominantly as the NT-H tautomer of the monocation (IIa) at a physiological pH of 7.4 and structure-activity studies indicate that this tautomer is likely to be the pharmacologically active species for both H1 and H2 receptors. Effective H2-receptor agonists appear to require a prototropic tautomeric system whereas H1-receptor agonists do not need to be tautomeric. This identifies a chemical difference in the receptor requirements which provides the basis for obtaining selective histamine H1-receptor agonists. Thus 2-(2-aminoethyl)thiazole and 2-(2-aminoethyl)pyridine are nontautomeric and are highly selective agonists for histamine H1 receptors (H1:H2 ca. 90:1 and 30:1, respectively). In conjunction with the selective H2-receptor agonist, 4-methylhistamine, they are of great value for studying the pharmacology of histamine receptors.

Marine Ecology Progress Series, 1997

Many species of the ubiquitous pennate diatom genus Pseudo-nitzschia have recently been discovere... more Many species of the ubiquitous pennate diatom genus Pseudo-nitzschia have recently been discovered to produce domoic acid, a potent neurotoxin which causes Amnesic Shellfish Poisoning (ASP). Pseudo-nitzschia spp. were extremely abundant (up to 108 cells 1-'; present in 67% of 2195 samples) from 1990 to 1994 on the Louisiana and Texas. USA, continental shelves and moderately abundant (up to 10' cells I-'; present in 18% of 192 samples) over oyster beds in the Terrebonne Bay estuary in Louisiana in 1993 and 1994. On the shelf there was a strong seasonal cycle with maxima every spring for 5 yr and sometimes in the fall, which were probably related to river flow, water column stability, and nutrient availability. In contrast, in the estuary there was no apparent seasonal cycle in abundance, but the time series of data is relatively short and the environment highly variable. At one site on the shelf, where sediment traps were deployed from spring to fall and sampled at frequent intervals in both 1990 and 1991, approximately 50% of the Pseudo-njtzschja spp. cells present in the water sank lnto sediment traps Pseudo-njtzschia spp. were also abundant In surficlal sediments. The species of Pseudo-nitzschla present during this study were not routinely identified with the methods employed. However, toxin-producing P multiserjes has been ident.ified previously from Galveston Bay, Texas, and cells from a bloom on the shelf in June 1993 were identified by scannlng electron microscopy as P. pseudodel~cat~ss~ma, whlch is sometimes toxic. Although there have been no known outbreaks of ASP in this area, hlstoncal data suggests that Pseudo-nltzschia spp. abundance may have Increased on the shelf since the 1950s It is hypothesized that the increase is due to doubling of the nutrlent loading from the Mississippi and Atchafalaya rivers and increased eutrophicat~on on the shelf.

Despite regulations controlling anthropogenic mercury sources in North America, high levels of me... more Despite regulations controlling anthropogenic mercury sources in North America, high levels of mercury in coastal fish and shellfish are an ongoing problem in Maritime Canada and the Northeastern United States. This study presents sediment core data from a macrotidal estuary located at the mouth of the Bay of Fundy showing stratigraphic profiles of total and methylmercury concentrations and potential methylation rates measured using stable mercury isotopes. The results show that in contrast to the expected methylmercury profile typically observed in unmixed sediments, methylmercury production occurs throughout the estimated 15-cm-thick active surface layer of these well-mixed sediments. The resulting large reservoir of methylmercury in these sediments helps to explain why mercury concentrations in organisms in this system remain high despite emissions reductions. Current management policies should take into account the expected delay in the response time of wellmixed estuarine systems to declines in mercury loading, considering the greater reservoir of historic mercury available in these sediments that can potentially be converted to methylmercury and biomagnify in coastal food chains. D

Geological Survey of Canada, Open File 7150, 2012

Educational Studies, 1981

Visual Arts Research, 2010

Studies in Art Education, 1998

Studies in Art Education, 2001

Marine Pollution Bulletin, 2008

Four coral-dominated coastal sites within two embayments (Kealakekua Bay and Honokō hau Bay) on t... more Four coral-dominated coastal sites within two embayments (Kealakekua Bay and Honokō hau Bay) on the lee of the island of Hawai'i were studied to assess evidence of anthropogenic impacts in these relatively pristine locales. Nutrient-loading parameters were analyzed in relation to benthic composition data. Statistically, there were significant positive relationships between nitrate + nitrite, silicate, and ammonium with the abundance of macroalgae, coralline algae, and dead coral, and between d 15 N and dead coral abundance. The north outside site of Kealakekua Bay and the south outside site of Honokō hau Bay appear to be most impacted by nutrient-loading factors in each bay, respectively. Comparisons with past nutrient data indicate that nutrient inputs have increased to the two bays, and that early impacts of these increased loadings are evident. It is predicted that at current nutrient-loading rates, the north sites of Kealakekua Bay and the south sites of Honokō hau Bay will exhibit evidence of further degradation in future years.

Marine Ecology Progress Series, 2001

Domoic acid (DA), a potent neurotoxin, is synthesized by certain members of the ubiquitous marine... more Domoic acid (DA), a potent neurotoxin, is synthesized by certain members of the ubiquitous marine diatom genus Pseudo-nitzschia. We recently detected elevated concentrations of DA in phytoplankton field samples from the northern Gulf of Mexico. In searching for a possible source of the toxin, we used a receptor-binding assay to detect DA activity in cultures of P. sp. cf. pseudodelicatissima (Hasle) isolated from this region and confirmed its presence in 2 of 7 clones using liquid chromatography coupled with tandem mass-spectrometric detection (LC-MS/MS). Unlike other toxic Pseudo-nitzschia species examined previously (e.g., P. multiseries, P. australis), cellular levels and net production of DA in these clones were highest in the early exponential phase, while the population growth rate was high and cell concentration was low. There was a negative correlation between cellular DA and cell concentration. The maximum cellular DA activity in cultures was 36 fg DA equiv. cell -1 . No net toxin production was evident in the stationary phase, yet extracellular DA levels increased markedly during this period to as much as 88% of the total DA in the cultures. Interestingly, these 2 toxic clones were able to enlarge their cell size after the apical axes declined to 15 to 25 µm, and these larger cells had considerably higher levels of DA than the original small cells. This study unequivocally establishes P. sp. cf. pseudodelicatissima as a source of DA in the northern Gulf of Mexico. Moreover, our work suggests that rapidly growing, rather than nutrient-limited, populations of this diatom should yield maximum net DA production rates and DA cell quotas. Thus, the presence of P. sp. cf. pseudodelicatissima cells, even at the low levels of early, rapidly growing bloom stages, can potentially lead to toxic events.

Limnology and Oceanography, 2002

Pseudo-nitzschia H. Peragallo, a marine planktonic diatom genus containing some species capable o... more Pseudo-nitzschia H. Peragallo, a marine planktonic diatom genus containing some species capable of producing the neurotoxin domoic acid, is often documented in extremely high concentrations in the northern Gulf of Mexico in the plume of the Mississippi River, especially when river flow and nutrient inputs are high. Limited historical data suggest that Pseudo-nitzschia abundance has increased in the northern Gulf of Mexico since the 1950s. Five sediment cores were collected and analyzed to test whether Pseudo-nitzschia increases coincided with increasing nutrient concentrations in the Mississippi River, thereby suggesting a cause-effect relationship. Pseudo-nitzschia abundance increased in all five cores, correlating significantly with increasing nitrate fluxes and decreasing silicate to nitrate ratios. A diatom dissolution index, based partly on scanning electron microscopic analysis of the fine structure of Pseudo-nitzschia and other lightly silicified diatom valves preserved in the sediment, indicates that the increase in Pseudo-nitzschia abundance appears to reflect a response to eutrophication rather than diagenesis. This study provides evidence for a possible link between coastal eutrophication and harmful algal blooms.

Journal of Phycology, 1999

An 18-month field survey of the Pseudo-nitzschia population present in Louisiana coastal waters w... more An 18-month field survey of the Pseudo-nitzschia population present in Louisiana coastal waters was conducted comparing species abundance estimates by novel fluorescent molecular probes (16S large subunit rDNA oligonucleotide sequences) with traditional electron and differential-interference light microscopy. While the probe and microscopic analyses agreed on the presence or absence of four common Pseudo-nitzschia species (P. multiseries (Hasle) Hasle, P. pseudodelicatissima (Hasle) Hasle, P. delicatissima (P.T. Cleve) Heiden, and P. pungens (Grunow) Hasle in 66% of the samples analyzed, the probes gave conflicting results with the microscopic methods in the remaining 34% of the samples. The majority of the discrepancies appear to be because of genetic variation within the Pseudo-nitzschia population, especially in P. pseudodelicatissima, indicating that the Monterey Bay Pseudo-nitzschia spp. may not be appropriate reference strains for distinguishing Louisiana Pseudo-nitzschia spp. Additionally, P. pseudodelicatissima has been associated with domoic acid (DA) activity in three field samples, at levels up to 22 times higher than the highest value given in 1 other published reports of DA production by this species. The contemporaneous existence of multiple strains of P. pseudodelicatissima (toxic and nontoxic) presents new challenges to the study of the ecophysiology and population dynamics of this bloom-forming species.