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Biomedical subjects

R T Sterner

Publications and source records attributed to R T Sterner.

18 recordsLinked to original sources
PubMed2000

Strychnine alkaloid and avian reproduction: effects occur at lower dietary concentrations with mallard ducks than with bobwhite quail.

Separate subchronic reproductive toxicity studies were conducted using mallard ducks (Anas platyrhynchos) and northern bobwhite quail (Colinus virginianus). Three groups (32/group; 16 male-female pairs) of 17-week-old ducks (F0 generation) were fed Purina Game Bird Breeder Layena diets containing mean (+/-SD) 33.2 (+/-2.7), 68.9 (+/-1.8), and 140.9 (+/-5.1) microg/g strychnine for 20 weeks, with some pairs in each group fed control diet during a subsequent 3-week recovery period. Three groups (32/group; 16 male-female pairs) of 19-week-old quail (F0 generation) were fed similar diets containing mean (+/-SD) 279.2 (+/-10.1), 557.4 (+/-43.5), and 1,113.6 (+/-46.6) microg/g strychnine for 22 weeks without a recovery period. Separate groups of ducks and quail (32/group; 16 male-female pairs) were also fed control diets (0.0 microg/g strychnine) in each study. There were 16 weekly collections of eggs for the mallard study (13 for the diet-exposure period and 3 for the recovery period), and 11 collections for the quail study. Eggs laid during the last 13 and 10 weeks of the diet-exposure periods for ducks (plus 3 weeks of the recovery period) and quail, respectively, were incubated. Each hatch of F1 generation ducklings and chicks was observed for 14 days. Key results were: (1) the no observed adverse effect levels (NOAELs) for F0 ducks and quail were 33.2 and 1,113.6 microg/g strychnine, respectively--quail showed no reproductive effects at the current doses; (2) decreased egg production and hatching success occurred for mallard hens fed mean 140.9 microg/g strychnine diets; and (3) "normal-hatching" ducklings from eggs of F0 mallards fed mean 140.9 microg/g strychnine diets suffered greater mortality than ducklings from the other diet groups. Possible mechanisms of strychnine action on avian reproduction are discussed.

Animals↗
PubMed1999

Capsicum-laden soils decrease contact time by northern pocket gophers.

Fossorial rodents damage lawns/water impoundments/crops. We conducted a two-choice, parametric-type study to determine the effects of capsicum-oleoresin/soil mixtures (0.00, 0.75, 1.50, and 2.25%) upon soil-contact, soil-digging, and pelage-grooming behaviors in northern pocket gophers (Thomomys talpoides). In 3 alternate-day (1-h/day) exposures to > or = 1.50% capsicum-oleoresin soil mixtures, gophers decreased mean soil contact time by 46% relative to placebo-exposed animals. Grooming time yielded a concentration x trial interaction that showed intense grooming by capsicum-exposed animals during trial 1, with "convergence" of times to near those of the "placebos" (0.00% capsicum oleoresin) by trial 3. The significant decrease in grooming activity was attributed to the gophers' reduced contact with capsicum soil across repeated exposures, rather than to chemical habituation. Soil-digging behaviors were minimally affected. Results demonstrate the feasibility of deterring gopher habitation by mixing chemical irritants in soil.

Analysis of Variance↗
PubMed1998

Subchronic dietary toxicity of strychnine: bobwhite quail are less sensitive than mallard ducks.

Separate, 28-day, subchronic studies of strychnine dietary toxicity were conducted using northern bobwhite quail (Colinus virginianus) and mallard ducks (Anas platyrhynchos). Five groups (five males five females/group) of 29-week-old quail were fed Purina(R) Game Bird Breeder Layena(R) diets containing mean (+/-SD) 484.2 (+/-17.0), 972. 6 (+/-54.0), 1,870.8 (+/-176.1), 3,516.7 (+/-68.0), and 6,083.3 (+/-269.6) microgram/g strychnine; whereas five groups of 27-week-old mallards (five males five females/group) were fed similar diets containing mean (+/-SD) 18.8 (+/-1.3), 91.1 (+/-27.3), 235.0 (+/-33. 8), 484.2 (+/-17.0), and 972.6 (+/-54.0) microgram/g strychnine. Separate "vehicle control" (0.0 microgram/g strychnine) groups (five males, five females/group) were included in each study. Strychnine toxicity was much less pronounced in quail; no observed effect concentrations (NOECs) were 972.6 (+/-54.0) and 91.1 (+/-27.3) microgram/g strychnine for quail and ducks, respectively. Several possible explanations for the species effects are offered, and some practical issues affecting the conduct of long-term, dietary toxicity studies are discussed.

Animals↗
PubMed1997

3-Chloro-p-toluidine hydrochloride: in vitro mutagenicity studies for human health hazards determinations.

3-Chloro-p-toluidine hydrochloride (CPT-HCl) is an aniline derivative used in the manufacture of the dye palatine fast yellow; it is also registered as a selective, low-volume-use (< 45 kg/yr) avicide. Three in vitro mutagenicity tests of CPT-HCl were performed according to methods recommended by the U.S. Environmental Protection Agency (EPA): the Ames/Salmonella assay, the Chinese hamster ovary/hypoxanthine-guanine phosphoribosyl-transferase (CHO/HPRT) mammalian cell forward gene mutation assay, and the CHO chromosome aberration assay. CPT-HCl did not display mutagenic activity using the Ames/Salmonella or CHO/HPRT assays. However, CPT-HCl induced statistically significant, concentration-dependent, metabolically activated increases in the proportion of aberrant cells and aberrations/cell in cultured CHO cells. Results are suggestive of minimal mutagenicity effects associated with exposure to anilines and their derivatives.

Animals↗
PubMed1995

Regressors of whole-carcass zinc phosphide/phosphine residues in voles: indirect evidence of low hazards to predators/scavengers.

Whole-carcass residues of the rodenticide zinc phosphide (Zn3P2) and hydrolyzed phosphine (PH3) were determined for voles (Microtus spp.) that died following ingestion of a 2% Zn3P2 steam rolled oat (SRO) groats bait. Procedures involved: a three-day acceptance test to assess vole consumption (n = 27) of control SRO groats and several one-day Zn3P2- (n = 13) or control-bait (n = 4) tests to characterize onset of pharmacotoxic signs and to obtain fatally-dosed carcasses for residue analyses. Carcasses were stored in liquid nitrogen (LN2) to maximize retention of Zn3P2/PH3 residues prior to chemical determinations. Linear regressions were computed between pairs of consumption and residue variables. Main results were the following: (1) mean (+/- SD) consumption of control bait was 2.5 (+/- 0.9), 3.0 (+/- 0.9), and 2.8 (+/- 0.8) g on days 1, 2, and 3, respectively (> or = 10.6 +/- 4.6% of body weight); (2) all test-bait voles (n = 13) died approximately 4-12 h after bait presentation, with lethargy and respiratory distress key signs of toxicosis; (3) whole-carcass Zn3P2 residues averaged 1.73 mg (min-max: 0.31-4.95), and PH3 residues averaged 10.6 micrograms (min-max: 0.5-21.0); and (4) significant linear regressions were found between bait consumption/Zn3P2 intake and body weight (r2 = 0.64, p < or = 0.001), carcass Zn3P2 and bait consumption/Zn3P2 intake (r2 = 0.32, p < or = 0.043), and carcass Zn3P2 and body weight (r2 = 0.60, p < or = 0.002). Certain analytical and hazards issues are discussed.

Animals↗
PubMed1993

Whole body exposures to a phosphoric acids aerosol: I. Spontaneous activity effects in wild rodent and avian species.

Two inhalation-chamber studies were conducted to assess acute (2-h out-of-chamber) and subacute (< or = 6 d postexposure) spontaneous activity effects of whole-body phosphoric acids aerosol exposure(s) in black-tailed prairie dogs (Cynomys ludovicianus) and rock doves (Columba livia). The aerosol was generated using a red phosphorus/butyl rubber (RP/BR) mixture under development as a military obscurant. Each study involved (1) 3 RP/BR target concentration groups [0.0 (controls), 1.0, and 4.0 mg/L], (2) 24 prairie dogs or rock doves (8/group), with gender included as a factor, (3) a successive 3-phase paradigm (2 d preexposure; 4 and 2 d of about 80 min/d exposures to RP/BR for prairie dogs and rock doves, respectively; and 6 d postexposure), and (4) infrared detection of the rodents'/birds' home-cage movements. In-chamber atmospheres were uniform and acceptable for all exposures; median aerosol mass concentrations ranged from 0.76 to 0.89 mg/L and 3.46 to 3.74 mg/L for the 1.0 and 4.0 mg/L groups, respectively, with median phosphoric acid (H3PO4) readings of between 67.2 and 74.3%; median particles were < or = 0.85 microns. Mortality was negligible; no prairie dogs died, but 1 male rock dove died on d 3 postexposure to two 4.0 mg/L target concentrations of RP/BR aerosol. Group x session interactions were significant for the acute activity counts of both species. The acute mean ambulatory (e.g., walking) counts of prairie dogs and the acute mean ambulatory and horizontal (e.g., preening) counts of rock doves exposed to 4.0 mg/L RP/BR aerosol were relatively less than those of the other groups after the first 2 or 1 exposures, respectively. Nevertheless, acute session means for all groups approximated or exceeded the 23 h/d activity measured during the pre- and postexposure phases--data indicating that chamber confinement caused a temporary, sharp increase in activity for both species irrespective of RP/BR aerosol concentrations. No RP/BR concentration-related, subacute shifts in the activity of the rodents/birds were observed.

Administration, Inhalation↗
PubMed1993

Whole-body exposures to a phosphoric acids aerosol: II. Food/water/weight effects in wild rodent and avian species.

Separate inhalation-chamber studies were conducted to assess acute/subacute food intake (g), water intake (ml), and body weight (g) effects of four whole-body phosphoric-acids-aerosol exposures in black-tailed prairie dogs (Cynomys ludovicianus); subacute effects of two exposures were studied in rock doves (Columba livia). A 95% red phosphorus/5% butyl rubber (RP/BR) mixture was burned to produce the aerosol. Each study involved (1) 3 RP/BR target concentration groups (0.0, 1.0, and 4.0 mg/L), (2) 24 prairie dogs or doves (8/group), with gender included as a factor in each study, and (3) a successive 3-phase paradigm (2 d preexposure; 4 and 2 d of approximately 80 min/d exposures to RP/BR for prairie dogs and rock doves, respectively; and 6 d postexposure). Results showed that in-chamber atmospheres were uniform and acceptable for all exposures. No prairie dogs died, but 1 male rock dove died on d 3 postexposure to 4.0 mg/L aerosol. Concentration and gender main effects were significant for the acute (2 h out-of-chamber) food intake, water intake, and weight change of prairie dogs, with aerosol-exposed and male rodents showing decrements. Gender and day main effects were also significant for the subacute (23 h/d) variables in prairie dogs; females weighted less than males, and reduced food/water/weight was evident for all animals during the 4 exposure days and first 3 postexposure days. For rock doves, subacute gender and day main effects, plus concentration x day and concentration x gender x day interactions, characterized the data. A transitive relationship was evident among RP/BR aerosol conditions (0.0 < 1.0 < 4.0 mg/L) and mean decreased food intakes on the exposure days (d2 < d1). Enhanced postexposure water replenishment by female versus male doves exposed to 4.0 mg/L RP/BR aerosol was a main finding. Results are explained based upon a temporal model of phosphoric acid caused ulcers/edema. Effects are compared to prior evidence for albino rats, prairie dogs and rock doves; these are also discussed relative to certain human health and ecotoxicological literature.

Aerosols↗
PubMed1990

Plasma lithium as a marker of lithium chloride in wild Norway rats (R. norvegicus).

A parametric study was conducted to determine the efficacy of plasma lithium as a marker of lithium chloride ingestion and dose in conditioned taste aversion research with rats. Separate groups of male wild Norway rats were given 60, 120 and 240 mg/kg doses of a lithium chloride solution by gavage. At 0.5, 1, 2, 24, 48 and 72 hr after dosing, 2-3 cc samples of blood were taken from each rat: these were centrifuged and 0.5-1.0 cc specimens of plasma were frozen for later analysis. Flameless atomic absorption spectroscopy was then used to determine quantities (ppm) of lithium in these specimens. Analyses of the data revealed that plasma lithium was both dose and time dependent; however, uptake and elimination of the lithium was rapid (less than or equal to 48 hr for 60 and 120 mg/kg-dosed rats). Results showed that measurements of plasma lithium has some utility as a marker of lithium chloride ingestion in laboratory studies, but limited potential in field studies, of conditioned taste aversion with rats.

Animals↗
PubMed1977

Psychomotor rehearsal: enhancement of rotary-pursuit tracking using a massed-training procedure.

Two groups of male volunteers (n = 8/group) performed 14 10-min. sessions of either alternate 30-sec. rotary-pursuit tracking and rehearsal of tracking or rotary-pursuit tracking and object-slide naming (nonrehearsal). Ten-min. problem-solving tasks separated these sessions. Results showed that subjects in the rotary-pursuit/mental rehearsal group displayed significantly enhanced tracking performance relative to those in the rotary-pursuit/object slide group, i.e., mean time-on-target scores of 12.8 sec. and 8.9 sec. per trial, respectively.

Adolescent↗
PubMedDate not supplied

FIFRA-88, GLP, and QA: pesticide registration.

The 1988 amendment to the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA-88) has decreased the number of pesticide registrations in the United States. Subsequent implementation of the U.S. Environmental Protection Agency (EPA) Good Laboratory Practice (GLP) and quality assurance (QA) standards has increased costs of maintaining these registrations. The U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) maintains approximately 30 Section 3 (federal) or Section 24c (state) vertebrate pesticide registrations for the Wildlife Services (WS) program to control wild mammals and birds that damage crops, impact endangered species, or pose human health risks. Under FIFRA-88, APHIS summarized, performed, and submitted or gained waivers for > 500 studies requested by the U.S. EPA to assess potential hazards/effects of these pesticides. A summary of FIFRA-88 milestones for registration of 3-chloro-p-toluidine hydrochloride (CPTH), the active ingredient (AI) in a "low-volume, minor-use" avicide (DRC-1339, Starlicide), is used to illustrate GLP/QA/animal welfare issues involved in this process. Trends in the development of new pesticides and veterinary drugs are compared to provide some perspectives on future career paths for QA professionals.

Animal Welfare↗