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1991

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Articles 1 - 15 of 15

Full-Text Articles in Pharmacology, Toxicology and Environmental Health

Hepatic Microsomal N-Hydroxylation Of Aniline And 4-Chloroaniline By Rainbow Trout (Onchorhyncus Mykiss), Steven P. Bradbury, J. M. Dady, A. D. Hoffman, M. M. Voit, D. L. Olson Dec 1991

Hepatic Microsomal N-Hydroxylation Of Aniline And 4-Chloroaniline By Rainbow Trout (Onchorhyncus Mykiss), Steven P. Bradbury, J. M. Dady, A. D. Hoffman, M. M. Voit, D. L. Olson

Steven P. Bradbury

N-Hydroxylation of aniline and 4-chloroaniline was quantified in rainbow trout microsomal preparations using h.p.l.c.-liquid scintillation methods. Radioactive phenylhydroxylamine and 4-chlorophenylhydroxylamine metabolites were identified by co-elution with non-labelled standards. The method provided resolution of metabolite standards, and quantification of both N-hydroxylated metabolites was achieved without derivatization. The maximum velocities at 25 degrees C were 33.8 +/- 1.40 and 22.0 +/- 0.98 pmol/min per mg for aniline and 4-chloroaniline N-hydroxylation, respectively. The Km values were 1.0 +/- 0.11 and 0.8 +/- 0.11 mM for aniline and 4-chloroaniline N-hydroxylation, respectively. These activities were not induced by treatment of the trout with Aroclor 1254 …

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Cocaine And Timing: Drug Effects Under A Mixed Fixed-Interval Extinction Schedule, Vincent O. Hodge Aug 1991

Cocaine And Timing: Drug Effects Under A Mixed Fixed-Interval Extinction Schedule, Vincent O. Hodge

Masters Theses

The effects of cocaine hydrochloride (3.2-56.2 mg/kg) were determined in rats performing under a mixed fixed-interval 60-seconds extinction 120-seconds schedule of food delivery. Responses were recorded in successive 5-second bins. With the exception of the highest dose (56.2 mg/kg), cocaine did not significantly affect rate of responding under the fixed-interval component or extinction component, or the time of peak responding under the extinction component. The highest dose significantly reduced response rates and shifted the time of peak responding leftward to quicker and earlier moments. Results are discussed in terms of possible rate- and time-dependent effects of stimulant drugs.

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1-Nitronaphthalene Causes Ultrastructural Changes Primarily In Nonciliated Bronchiolar Epithelium Followed By Ciliated Epithelium In The Rat, John-Michael Sauer Jun 1991

1-Nitronaphthalene Causes Ultrastructural Changes Primarily In Nonciliated Bronchiolar Epithelium Followed By Ciliated Epithelium In The Rat, John-Michael Sauer

Masters Theses

This study describes morphological changes in the lung at several time intervals following a single injection of 1-Nitronaphthalene (100 mg/kg intraperitoneal) in male Sprague-Dawley rats using transmission and scanning electron microscopy. Dilation of the smooth endoplasmic reticulum and mitochondrial distension in the nonciliated bronchiolar (Clara) cells was apparent as early as 1 hour after injection, while adjacent ciliated cell showed minimal changes. At 6 hours, when respiratory distress was apparent in the animals, Clara and ciliated cells exhibited chromatin clumping, loss of mitochondrial cristae and cytoplasmic vacuolization. Also at 6 hours, the interstitial area around the terminal bronchioles was infiltrated …

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Nitrogen Dioxide Reaction With Proteins: Evidence For Peptide Bond Cleavage At Lysine Residues, Darryl B. Hood May 1991

Nitrogen Dioxide Reaction With Proteins: Evidence For Peptide Bond Cleavage At Lysine Residues, Darryl B. Hood

Electronic Theses and Dissertations

Nitrogen dioxide (NO$\sb2$), an air pollutant produced by burning fossil fuels and a component of cigarette smoke, is thought to contribute to the pathogenesis of pulmonary diseases, such as emphysema. To gain information on the mechanism by which NO$\sb2$ damages the lung, in vitro exposures of $\alpha\sb1$-proteinase inhibitor ($\alpha\sb1$-PI), elastin, bovine serum albumin (BSA), human serum albumin (HSA) and synthetic poly-L-lysine were performed. A genetic deficiency of $\alpha\sb1$-PI predisposes humans to emphysema and NO$\sb2$ has been hypothesized to damage $\alpha\sb1$-PI, which would leave proteases such as human neutrophil elastase, (HNE) free to attack lung structural proteins. The ability of $\alpha\sb1$-PI …

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Biological Detoxification Of Mercury Contaminated Soil, Shiying Zhang May 1991

Biological Detoxification Of Mercury Contaminated Soil, Shiying Zhang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study examined biological mercury removal from soil using mercury-resistant bacteria in soil microcosms. Mercuric chloride was used to artificially contaminate Kidman soil to mercury concentrations of 5 ppm and 10 ppm. Soil moisture content was maintained at three levels, 20%, 30% and 50%. Mercury resistant-bacteria were added to soil samples and the mercury removal rate was compared to control samples without added bacteria. Mercury removal rate was initially enhanced by the addition of bacteria. After 30 days, no difference was observed between samples and controls with initial mercury concentration of 5 ppm when soil moisture content was 20%. At …

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Effects Of Phenobarbital In Combination With Phenytoin Or Valproic Acid On The Delayed-Matching-To-Sample Performance Of Pigeons, Catherine Ann Karas Apr 1991

Effects Of Phenobarbital In Combination With Phenytoin Or Valproic Acid On The Delayed-Matching-To-Sample Performance Of Pigeons, Catherine Ann Karas

Masters Theses

The present study examined the effects of phenobarbital (S, 10,20, and 40 mg/kg), phenytoin (2.5, 5, 7.5, and 15 mg/kg), and valproic acid (40, 60, 80, and 120 mg/kg), and those of phenobarbital (10 and 20 mg/kg) in combination with phenytoin (2.5,5, and 7.5 mg/kg) or valproic acid (40, 60, and 80 mg/kg), on the delayed-matching-to-sample performance of pigeons. In general, high doses of each individual drug reduced accuracy. Drug combinations also reduced accuracy relative to control values. Reductions in accuracy produced by drug combinations were very similar in magnitude to those predicted by a response-addition model of drug interaction.

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A Biochemical Study Of Gossypol And Lactate Dehydrogenase X Binary Interactions, Patricia Brown Ravenell Apr 1991

A Biochemical Study Of Gossypol And Lactate Dehydrogenase X Binary Interactions, Patricia Brown Ravenell

Theses and Dissertations in Biomedical Sciences

The goal of this project was to study the mechanism of action of gossypol through its (a) binary interaction with native and trypsin digested lactate dehydrogenase-X (LD-X), a sperm-specific isozyme, and (b) its binding in vitro in primary cultures of spermatogenic cells. Mouse LD-X was cleaved with trypsin before and after treatment with gossypol. This was followed by high performance chromatography (HPLC) separation of the LD-X tryptic peptide fragments to observed alterations in separation patterns as indicators of intramolecular disturbance in the enzyme molecule. Definite alterations in peptide fragment peaks were observed in the presence of gossypol and suggest conformational …

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Regulating Air Toxics In Rhode Island: Policy Vs. Technical Decisions, Julie A. Roque Mar 1991

Regulating Air Toxics In Rhode Island: Policy Vs. Technical Decisions, Julie A. Roque

RISK: Health, Safety & Environment (1990-2002)

Dr. Roqu6 recounts her work as a doctoral candidate at Brown in developing standards for the regulation of airborne carcinogens. Based in part on this experience, she argues that care needs be taken lest those who regulate Risk bury key policy decisions within a mass of often irrelevant technical details.

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Serotonergic Suppression Of Interhemispheric Synaptic Potentials In The Rat Prefrontal Cortex, Heather Lynn Read Jan 1991

Serotonergic Suppression Of Interhemispheric Synaptic Potentials In The Rat Prefrontal Cortex, Heather Lynn Read

Dissertations

No abstract provided.

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Inhibition Of Alcohol Dehydrogenase Activity By Acetylenic And Allylic Alcohols: Concordance With In Vivo Electrophile Reactivity In Fish, Steven P. Bradbury, Glenn M. Christensen Jan 1991

Inhibition Of Alcohol Dehydrogenase Activity By Acetylenic And Allylic Alcohols: Concordance With In Vivo Electrophile Reactivity In Fish, Steven P. Bradbury, Glenn M. Christensen

Steven P. Bradbury

Acetylenic and al!ylic alcohols have been reported to be 20 to 5,000 times more acutely toxic to fathead minnows (Pimephales promelas) than would be expected from a narcosis-based mechanism of action. The greater-than-expected toxicity of these alcohols has been proposed to be a result of metabolic activation to the corresponding reactive a ,)3-unsaturated aldehydes or allene derivatives. Using purified horse liver and rainbow trout (Oncorhynchus mykiss) hepatic cytosol alcohol dehydrogenase (ADH) preparations, the propensity of a series of acetylenic and allylic alcohols to inhibit enzyme activity, in both the presence and the absence of reduced glutathione, was ascertained. Those alcohols …

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Use Of Respiratory-Cardiovascular Responses Of Rainbow Trout (Oncorhynchus Mykiss) In Identifying Acute Toxicity Syndromes In Fish: Part 4. Central Nervous System Seizure Agents, Steven P. Bradbury, Richard W. Carlson, Gerald J. Niemi, Tala R. Henry Jan 1991

Use Of Respiratory-Cardiovascular Responses Of Rainbow Trout (Oncorhynchus Mykiss) In Identifying Acute Toxicity Syndromes In Fish: Part 4. Central Nervous System Seizure Agents, Steven P. Bradbury, Richard W. Carlson, Gerald J. Niemi, Tala R. Henry

Steven P. Bradbury

The respiratory-cardiovascular responses of spinally transected rainbow trout to acutely lethal concentrations of chlorpyrifos, cypermethrin, fenvalerate, endosulfan, endrin, and strychnine were examined. Common to all six toxicants, the most striking change in respiratory-cardiovascular parameters was an increased cough frequency. Ventilation frequency and volume dropped in strychnine-exposed trout, but both remained near predose levels (frequency) or elevated (volume) in the pyrethroid- and cyclodiene-exposed trout. In chlorpyrifos-intoxicated trout, ventilation frequency decreased while volume increased. Oxygen consumption remained near predose levels in the chlorpyrifos-, pyrethroid-, and strychnine-exposed trout, but increased dramatically in the cyclodiene-exposed trout. Arterial oxygen, carbon dioxide, and pH declined in …

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Pharmaceutical Risk And The Quality Of Life, Beat Hiltbrunner, Andreas Breitsprecher Jan 1991

Pharmaceutical Risk And The Quality Of Life, Beat Hiltbrunner, Andreas Breitsprecher

RISK: Health, Safety & Environment (1990-2002)

Quality-of-life research is briefly described and said to be in its infancy. However, the authors observe that such studies may, e.g., make it possible to better match patients and therapies. They also predict that, as scientific difficulties are overcome, the pharmaceutical industry will become more active in planning, implementing and evaluating such research.

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Monooxygenase Induction And Lethality As Endpoints In Aquatic Toxicology, Daniel W. Sved Jan 1991

Monooxygenase Induction And Lethality As Endpoints In Aquatic Toxicology, Daniel W. Sved

Dissertations, Theses, and Masters Projects

Spot, Leiostomus xanthurus, were exposed to suspended sediments (&\approx&20 mg/L) contaminated with polycyclic aromatic hydrocarbons (PAH) in a laboratory flow-through system to evaluate the applicability of hepatic ethoxyresorufin O-deethylase (EROD) induction as an indicator of PAH exposure. PAH sources tested were coal-tar creosote (CTC), a low molecular weight fraction of creosote (LMWF), and a high molecular weight fraction of creosote (HMWF). A standard 96-h acute toxicity test was conducted to ensure that PAH concentrations tested in induction studies were sub-acutely toxic. The 96-h LC50 for spot was 1740 &\mu&g PAH/L (95% confidence interval = 1480-2060 &\mu&g PAH/L). The lowest concentration …

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Sediment Denitrification Potential In The Elizabeth River, Virginia, Surena Fazeli-Matin, Andrew S. Gordon, Harold G. Marshall Jan 1991

Sediment Denitrification Potential In The Elizabeth River, Virginia, Surena Fazeli-Matin, Andrew S. Gordon, Harold G. Marshall

Biological Sciences Faculty Publications

Sediment denitrification potential from two sites in the Elizabeth River estuary was studied over a nine-month period using the acetylene blockage method. Rates of microbial processes in this environment are of interest because of the high concentration of toxics present in some parts of the system. Highest rates were found in the highly polluted Southern Branch of the Elizabeth River with nitrate amended sediment ranging from 2-262 nmol N20/h per 20ml of sediment and exhibiting maximal rates during spring and fall. Rates in the Main Stem of the Elizabeth River were lower, with less than 1-85 nmol N …

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Effects Of 2,3,7,8-Tetrachlorodibenzo-P-Dioxin (Tcdd) On The In Vitro Antibody Response: Differential Effects On The B Lymphocyte Depending On The State Of In Vivo Activation And The Modulation By Serum-Derived Growth Factors, Dale L. Morris Jan 1991

Effects Of 2,3,7,8-Tetrachlorodibenzo-P-Dioxin (Tcdd) On The In Vitro Antibody Response: Differential Effects On The B Lymphocyte Depending On The State Of In Vivo Activation And The Modulation By Serum-Derived Growth Factors, Dale L. Morris

Theses and Dissertations

Previous reports have indicated a dichotomy in the actions of TCDD on humoral immunity, both in vitro and in vitro, in which enhancements and suppression have been identified. The latter effect has been correlated with induction of liver P4501A1 enzyme activity, a response which is regulated by the Ah-gene locus. Additionally, the primary alteration in suppression of antibody responses is in the differentiation of the B cell. Therefore, the current investigation was undertaken to determine the relationship between these dual actions of TCDD on humoral immunity as related to its direct actions on B lymphocyte function. Specific emphasis was placed …

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