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Biomedical subjects

P J Shea

Publications and source records attributed to P J Shea.

33 records · Page 2Linked to original sources
PubMed1985

New bicyclic antidepressant agent. Synthesis and activity of napactadine and related compounds.

A number of N,N'-dialkylarylamidines were synthesized and evaluated for antidepressant activity. Several of these compounds were synthesized from the corresponding nitriles by a new method. Slight structural modification in the series caused a marked change in biological activity and led to compounds as active as imipramine. The arylacetamidine, N,N'-dimethyl-2-naphthaleneethanimidamide hydrochloride (33) (napactadine) was selected for clinical study. Forty-eight additional analogues of 33, including a number of N-alkylamidines, were prepared.

Aggression↗
PubMed1981

Toxicity of acephate and methamidophos to dark-eyed juncos.

The calculated, acute oral LD50 of acephate and methamidophos to dark-eyed juncos (Junco hyemalis) was 106 mg/kg and 8 mg/kg, respectively. Brain cholinesterase (ChE) activity in birds that died after acephate poisoning was depressed 80% below that of control birds. Birds that died of acute methamidophos poisoning had brain ChE depression of 60%. The birds killed by acephate had brain acephate residue concentrations greater than 2 mg/kg and methamidophos concentrations usually greater than 0.25 mg/kg. Eighty percent of the birds killed with methamidophos had brain methamidophos concentrations greater than 0.1 mg/kg. The five-day feeding LC50 for acephate was 1485 mg/kg. Brain ChE activities of birds which died early in the study were less depressed (51.5%) than those which died at a later date (69.6%). Brain residues of acephate and methamidophos were lower in these birds than in the birds of the acute oral LD50 studies. Brain ChE activity returned to normal within three days after the birds received a single sublethal dose of acephate. These studies indicate that the amount of acephate needed to produce the ChE depression found in other investigations in most dark-eyed juncos exposed to forest applications of insecticide is about one-fifth of the LD50; however, in a few birds the ChE activity may be depressed to near lethal levels.

Animals↗
PubMedDate not supplied

Field-scale remediation of a metolachlor-contaminated spill site using zerovalent iron.

Pesticide spills are common occurrences at agricultural cooperatives and farmsteads. When inadvertent spills occur, chemicals normally beneficial can become point sources of ground and surface water contamination. We report results from a field trial where approximately 765 m3 of soil from a metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide] spill site was treated with zerovalent iron (Fe0). Preliminary laboratory experiments confirmed metolachlor dechlorination by Fe0 in aqueous solution and that this process could be accelerated by adding appropriate proportions of Al2(SO4)3 or acetic acid (CH3COOH). The field project was initiated by moving the stockpiled, contaminated soil into windrows using common earth-moving equipment. The soil was then mixed with water (0.35-0.40 kg H2O kg(-1)) and various combinations of 5% Fe0 (w/w),2% Al2(SO4)3 (w/w), and 0.5% acetic acid (v/w). Windrows were covered with clear plastic and incubated without additional mixing for 90 d. Approximately every 14 d, the plastic sheeting was removed for soil sampling and the surface of the windrows rewetted. Metolachlor concentrations were significantly reduced and varied among treatments. The addition of Fe0 alone decreased metolachlor concentration from 1789 to 504 mg kg(-1) within 90 d, whereas adding Fe0 with Al2(SO4)3 and CH3COOH decreased the concentration from 1402 to 13 mg kg(-1). These results provide evidence that zerovalent iron can be used for on-site, field-scale treatment of pesticide-contaminated soil.

Acetamides↗
PubMedDate not supplied

Metolachlor dechlorination by zerovalent iron during unsaturated transport.

Permeable zerovalent iron (Fe0) barriers have become an established technology for remediating contaminated ground water. This same technology may be applicable for treating pesticides amenable to dehalogenation as they move downward in the vadose zone. By conducting miscible displacement experiments in the laboratory with metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide; a chloroacetanilide herbicide] under unsaturated flow, we provide proof-of-concept for such an approach. Transport experiments were conducted in repacked, unsaturated soil columns attached to vacuum chambers and run under constant matrix potential (-30 kPa) and Darcy flux (approximately 2 cm d(-1)). Treatments included soil columns equipped with and without a permeable reactive barrier (PRB) consisting of a Fe0-sand (50:50) mixture supplemented with Al2(SO4)3. A continuous pulse of 14C-labeled metolachlor (1.45 mM) and tritiated water (3H2O) was applied to top of the columns for 10 d. Results indicated complete (100%) metolachlor destruction, with the dehalogenated product observed as the primary degradate in the leachate. Similar results were obtained with a 25:75 Fe0-sand barrier but metolachlor destruction was not as efficient when unannealed iron was used or Al2(SO4)3 was omitted from the barrier. A second set of transport experiments used metolachlor-contaminated soil in lieu of a 14C-metolachlor pulse. Under these conditions, the iron barrier decreased metolachlor concentration in the leachate by approximately 50%. These results provide initial evidence that permeable iron barriers can effectively reduce metolachlor leaching under unsaturated flow.

Acetamides↗
PubMedDate not supplied

Pilot-scale treatment of RDX-contaminated soil with zerovalent iron.

Soils in Technical Area 16 at Los Alamos National Laboratory (LANL) are severely contaminated from past explosives testing and research. Our objective was to conduct laboratory and pilot-scale experiments to determine if zerovalent iron (Fe(0)) could effectively transform RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) in two LANL soils that differed in physicochemical properties (Soils A and B). Laboratory tests indicated that Soil A was highly alkaline and needed to be acidified [with H2SO4, Al2(SO4)3, or CH3COOH] before Fe(0) could transform RDX. Pilot-scale experiments were performed by mixing Fe(0) and contaminated soil (70 kg), and acidifying amendments with a high-speed mixer that was a one-sixth replica of a field-scale unit. Soils were kept unsaturated (soil water content = 0.30-0.34 kg kg(-1)) and sampled with time (0-120 d). While adding CH3COOH improved the effectiveness of Fe(0) to remove RDX in Soil A (98% destruction), CH3COOH had a negative effect in Soil B. We believe that this difference is a result of high concentrations of organic matter and Ba. Adding CH3COOH to Soil B lowered pH and facilitated Ba release from BaSO4 or BaCO3, which decreased Fe(0) performance by promoting flocculation of humic material on the iron. Despite problems encountered with CH3COOH, pilot-scale treatment of Soil B (12 100 mg RDX kg(-1)) with Fe(0) or Fe(0) + Al2(SO4)3 showed high RDX destruction (96-98%). This indicates that RDX-contaminated soil can be remediated at the field scale with Fe(0) and soil-specific problems (i.e., alkalinity, high organic matter or Ba) can be overcome by adjustments to the Fe(0) treatment.

Environmental Pollution↗
PubMedDate not supplied

Enhancing metolachlor destruction rates with aluminum and iron salts during zerovalent iron treatment.

Pesticide-contaminated soil may require remediation to mitigate ground and surface water contamination. We determined the effectiveness of zerovalent iron (Fe(0)) to dechlorinate metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methyl ethyl) acetamide] in the presence of aluminum and iron salts. By treating aqueous solutions of metolachlor with Fe(0), we found destruction kinetics were greatly enhanced when Al, Fe(II), or Fe(II) salts were added, with the following order of destruction kinetics observed: Al2(SO4)3 > AlCl3 > Fe2(SO4)3 > FeCl3. A common observation was the formation of green rusts, mixed Fe(II)-Fe(III) hydroxides with interlayer anions that impart a greenish-blue color. Central to the mechanism responsible for enhanced metolachlor loss may be the role these salts play in facilitating Fe(II) release. By tracking Al and Fe(II) in a Fe(0) + Al2(SO4)3 treatment of metolachlor, we observed that Al was readily sorbed by the corroding iron with a corresponding release of Fe(II). The manufacturing process used to produce the Fe(0) also profoundly affected destruction rates. Metolachlor destruction rates with salt-amended Fe(0) were greater with annealed iron (indirectly heated under a reducing atmosphere) than unannealed iron. Moreover, the optimum pH for metolachlor dechlorination in water and soil differed between iron sources (pH 3 for unannealed, pH 5 for annealed). Our results indicate that metolachlor destruction by Fe(0) treatment may be enhanced by adding Fe or Al salts and creating pH and redox conditions favoring the formation of green rusts.

Acetamides↗
PubMedDate not supplied

Remediating munitions-contaminated soil with zerovalent iron and cationic surfactants.

Soils contaminated from military operations often contain mixtures of HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), and TNT (2,4,6-trinitrotoluene) rather than a single explosive. Differences among explosives in solubility and reactivity make developing a single remediation treatment difficult. When Fe(0) was used to treat a munitions-contaminated soil, we observed high rates of destruction for RDX and TNT (98%) but not HMX. Our objective was to determine if HMX destruction by Fe(0) could be enhanced by increasing HMX solubility by physical (temperature) or chemical (surfactants) means. To determine electron acceptor preference, we treated RDX and HMX with Fe(0) in homogeneous solutions and binary mixtures. Increasing aqueous temperature (20 to 55 degrees C) increased HMX solubility (2 to 22 mg L(-1)) but did not increase destruction by Fe(0) in a contaminated soil slurry that also contained RDX and TNT. Batch experiments using equal molar concentrations of RDX and HMX demonstrated that RDX was preferentially reduced over HMX by Fe(0). By testing various surfactants, we found that the cationic surfactants (HDTMA [hexadecyltrimethylammonium bromide], didecyl, and didodecyl) were most effective in increasing HMX concentration in solution. Didecyl and HDTMA were also found to be highly effective in facilitating the transformation of HMX by Fe(0). Using HDTMA or didecyl solutions (3%, w/v) containing solid-phase HMX, we observed that 100% of the added HMX was transformed by Fe(0) in the didecyl matrix and 60% in the HDTMA matrix. These results indicate that cationic surfactants can increase HMX solubility and facilitate Fe(0)-mediated transformation kinetics but HMX destruction rates will be slowed when RDX is present.

Azocines↗
PubMedDate not supplied

Use of the Florida Sexual History Questionnaire to differentiate primary organic from primary psychogenic impotence.

A recent study demonstrated the Florida Sexual History Questionnaire (FSHQ) is reliable and valid when used to discriminate impotent from nonimpotent men. This study examined the ability of the FSHQ to discriminate between men with primary psychogenic and primary organic impotence in a sample of impotent diabetics and a larger group of impotent men. The hit rate in the diabetic sample was 81% using an eight-item discriminant function, and 70% using the total score. Hit rates in the larger sample were significant but lower (73% and 66%). The results suggest that the FSHQ has concurrent validity in terms of discriminating primary organic from primary psychogenic impotence.

Diabetes Mellitus, Type 2↗