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Biomedical subjects

R S Bennett

Publications and source records attributed to R S Bennett.

At least 19 recordsLinked to original sources
PubMed2005

Case Study Part 1: How to calculate appropriate deterministic long-term toxicity to exposure ratios (TERs) for birds and mammals.

In the European Union, first-tier assessment of the long-term risk to birds and mammals from pesticides is based on calculation of a deterministic long-term toxicity/exposure ratio (TER(lt)). The ratio is developed from generic herbivores and insectivores and applied to all species. This paper describes two case studies that implement proposed improvements to the way long-term risk is assessed. These refined methods require calculation of a TER for each of five identified phases of reproduction (phase-specific TERs) and use of adjusted No Observed Effect Levels (NOELs) to incorporate variation in species sensitivity to pesticides. They also involve progressive refinement of the exposure estimate so that it applies to particular species, rather than generic indicators, and relates spraying date to onset of reproduction. The effect of using these new methods on the assessment of risk is described. Each refinement did not necessarily alter the calculated TER value in a way that was either predictable or consistent across both case studies. However, use of adjusted NOELs always reduced TERs, and relating spraying date to onset of reproduction increased most phase-specific TERs. The case studies suggested that the current first-tier TER(lt )assessment may underestimate risk in some circumstances and that phase-specific assessments can help identify appropriate risk-reduction measures. The way in which deterministic phase-specific assessments can currently be implemented to enhance first-tier assessment is outlined.

Animals↗
PubMed2005

Case Study Part 2: Probabilistic modelling of long-term effects of pesticides on individual breeding success in birds and mammals.

Long term exposure of skylarks to a fictitious insecticide and of wood mice to a fictitious fungicide were modelled probabilistically in a Monte Carlo simulation. Within the same simulation the consequences of exposure to pesticides on reproductive success were modelled using the toxicity-exposure-linking rules developed by R.S. Bennet et al. (2005) and the interspecies extrapolation factors suggested by R. Luttik et al. (2005). We built models to reflect a range of scenarios and as a result were able to show how exposure to pesticide might alter the number of individuals engaged in any given phase of the breeding cycle at any given time and predict the numbers of new adults at the season's end.

Animals↗
PubMed2004

Evidence of avian pneumovirus spread beyond Minnesota among wild and domestic birds in central North America.

To detect avian pneumovirus (APV) in central North America, nasal turbinates or choanal deft tissues from domestic turkeys and wild birds were examined for the presence of APV RNA by reverse transcriptase-polymerase chain reaction (RT-PCR), whereas serum samples from domestic turkeys were analyzed for APV antibodies by enzyme-linked immunosorbent assay (ELISA). In 2002, the seroprevalence of disease in domestic turkeys in Minnesota remained high (42.3% of the flocks). In addition, there is evidence the disease has spread to turkey flocks in North Dakota (8.2%), South Dakota (7%), Iowa (10%), and Wisconsin (8.6%) as detected by RT-PCR and/or ELISA. House sparrows and ring-billed gulls sampled in Minnesota and snow geese from Saskatchewan, Canada, were found to harbor APV RNA. Sequence analysis of wild bird APV strains showed high amino acid sequence identity among wild bird isolates (<97%) and between wild bird and turkey viral isolates (93.2%-99.3%). This study demonstrated that APV infections were present in domestic turkey flocks and wild birds outside the state of Minnesota; however, the role of wild birds in spreading APV to domestic turkeys remains unclear.

Amino Acid Sequence↗
PubMed2003

Identity and conservation of mating type genes in geographically diverse isolates of Phaeosphaeria nodorum.

Mating type idiomorphs (MAT1-1 and MAT1-2) were identified from the heterothallic loculoascomycete Phaeosphaeria nodorum (wheat biotype) using DNA from a pair of isolates from Poland and Georgia, USA that are known to mate. MAT predicted proteins of P. nodorum are similar in sequence and in phylogenetic relationship to those described for other loculoascomycetes such as Cochliobolus spp., Alternaria alternata, and Didymella zeae-maydis. The organization of the MAT locus of the P. nodorum differs from these species in that its idiomorph begins within an adjacent upstream conserved ORF of unknown function. MAT-specific primers were used to identify isolates of both mating types in field populations, demonstrating that an absence of either mating type is not the reason that the teleomorph has not been found in New York. Portions of MAT1-1 and MAT1-2 were sequenced from geographically diverse isolates, including those from regions where the teleomorph has been reported. MAT was highly conserved and no significant differences in sequence were found.

Amino Acid Sequence↗
PubMed2001

Distress and disease status among patients with rheumatoid arthritis: roles of coping styles and perceived responses from support providers.

Previous research has shown that social support can have a beneficial impact on coping processes and psychological adjustment in patients with rheumatoid arthritis (RA). The association of individual coping styles and perceived responses from others to one's pain episodes with patients 'distress and disease status over time was investigated. The sample consisted of 42 middle-aged patients with RA who were predominantly White (98%), female (64%), and married (88%). Participants completed surveys and their rheumatologist completed clinical assessments of patient disease status at 2 time points over a 9-month period. Although punishing responses from others (e.g., getting irritated or angry when the patient is in pain) were perceived as relatively infrequent, they were associated with a patient coping style of focusing on and venting of negative emotion as well as elevated negative affect (NA). Findings also indicated that those who perceived punishing responses from close others and coped by venting negative emotions reported increased NA over time and were rated by their rheumatologist as having more severe RA disease status over time. Implications for psychosocial intervention and directions for future research are discussed.

Adaptation, Psychological↗
PubMed1994

An interpretation of toxicity response of bobwhite quail with respect to duration of exposure.

Avian dietary toxicity tests were conducted with seven pesticides, two age groups (2 and 16 weeks old) of northern bobwhite (Colinus virginianus) and two durations (5 and 28 days) of exposure. Results were analyzed with an emphasis placed upon comparing mortalities on similar test conditions. An analysis that used the entire dose-time-response results led to the calculation of a common measure (asymptotic rate e) of temporal development of the response surface and served as a basis of comparison of diverse test results. The asymptotic median lethal concentrations were designated by ALC50 and the median lethal concentrations at the end of a test period by LC50. It was found that: (1) Young birds in 5- and 28-day tests were more sensitive to incremental increases in the duration of exposure than adults. (2) Young birds were less sensitive to incremental increases of dietary concentration than adults only in the 5-day test and displayed delayed response patterns in six of seven chemicals in those tests. (3) LC50 values of 5-day tests of young birds were greater than LC50 values of 28-day tests, but the corresponding ALC50s were smaller in 5-day tests than 28-day tests. (4) ALC50s for 28-day tests were lower for young birds than for adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1992

Comparative response of nestling European starlings and red-winged blackbirds to an oral administration of either dimethoate or chlorpyrifos.

Red-winged blackbird (Agelaius phoeniceus; blackbird) and European starling (Sturnus vulgaris; starling) nestlings were dosed with either 2.0 mg/kg body mass chlorpyrifos, 50.0 mg/kg body mass dimethoate, or a propylene glycol carrier in situ. Four growth measurements (body mass, culmen, tarsus, wing) were recorded from nestlings to determine if these organophosphorus compounds caused perturbations in development at sublethal concentrations. Blackbird nestlings were more sensitive to chlorpyrifos than starling nestlings were more sensitive to dimethoate than blackbird nestlings. This was in contrast to reported adult LD50 values where the reverse was true. Blackbird nestlings were more tolerant of a substantially higher concentration of dimethoate than the adult LD50. The sensitivity of starling nestlings to dimethoate was similar to adults. In contrast, juveniles of both species were more sensitive to chlorpyrifos than adults. After the initial 24 hr, surviving nestlings dosed with either chemical recovered and continued their development. Exposure to dimethoate caused significant depression in starling body mass during the initial 24 hr period. Survivors obtain body mass equal to controls within 48 hr post dosing. The research presented here demonstrates that the simple supposition that passerine nestlings are typically more sensitive to toxins than adults does not always hold true. It also indicates that sensitivity relationships among adults do not necessarily apply to their nestlings.

Administration, Oral↗
PubMed1991

Age-dependent changes in activity of mallard plasma cholinesterases.

Plasma acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activity was measured repeatedly in 27 mallard (Anas platyrhynchos) ducklings between 7 and 85 days of age to determine age-dependent changes in enzyme activity. Plasma AChE, BChE, and total cholinesterase (ChE) activity decreased significantly with age. The relative proportion of AChE in total ChE activity also decreased slightly with age. Since some anti-ChE chemicals can selectively inhibit AChE or BChE activity, characterization of age-dependent changes in the activity of each enzyme may be necessary to accurately identify the occurrence of pesticide exposure.

Acetylcholinesterase↗
PubMed1991

Efficacy of danazol in the control of hormonal migraine.

Of 131 women with hormonally related migraines unresponsive to standard medication, 67 (51.1%) noted profound relief after a 12-month, phased study using danazol for migraine prevention. The first three phases consisted of two-month cycles: dietary control and acetazolamide, the addition of danazol and danazol discontinuation. Eighty-three women (63.36%) reported control of their hormonal migraines while using danazol. In phase IV, 81 women whose headaches were controlled by danazol restarted danazol for an additional six months. Sixty-seven (82.7%) reported continued success with this medication. Danazol proved highly successful in the control of women's cyclic migraine. Its effectiveness remained consistent throughout the treatment course. In the prophylactic treatment of women's hormonal migraine, 400 mg of danazol administered daily for 25 days each month can prove effective when standard medical therapy fails. Furthermore, the response to danazol supported the concept that hormonal migraine should be treated as a distinct clinical entity.

Acetazolamide↗
PubMed1990

Pouch outlet obstruction following vertical ring gastroplasty for morbid obesity.

We have experienced a 14% (38 of 264 patients) incidence of pouch outlet obstruction following vertical ring gastroplasty. Initial management consisted of dilatation in 34 of 38 patients (94%). Ten of 34 patients (29%) were spared reoperation by 1 to 3 dilatations. Non-passage of an endoscope through the stoma immediately following dilatation predicted the need for surgery; 4 of 11 patients (36%) with passage underwent reoperation compared with 17 of 20 patients (85%) without passage (p less than 0.02). Surgical findings included "tipped bands" in 9 of 28 patients (32%); fibrous reaction to the band in 10 of 28 patients (36%); adhesions with angulation of the pouch in 2 of 28 patients (7%); and no identifiable cause of obstruction in 7 of 28 patients (25%). Surgical therapy consisted of removal of the band (2 patients), removal of the band and replacement with a similar length or larger band (20 patients), "tacking" the band in the horizontal position (4 patients), or conversion to a Roux-Y bypass (2 patients). The first three options were associated with an unacceptably high rate of weight regain and/or continued symptoms, whereas the last-named procedure met with good success.

Anastomosis, Roux-en-Y↗
PubMed1989

Factors influencing discrimination between insecticide-treated and untreated foods by northern bobwhite.

Tests were conducted to determine at what dietary concentrations northern bobwhite (Colinus virginianus) chicks (14 days old) could discriminate between pesticide-treated and untreated food using an organophosphate (OP) insecticide, parathion, and two carbamates, carbofuran and methiocarb. Results from subacute dietary LC50 tests (one feeder of treated food per cage) were compared to tests where birds were presented with two feeders (one treated and one untreated, 1:1) or 10 feeders (five treated and five untreated, 5:5; or nine treated and one untreated, 9:1). The dietary concentration above which birds discriminate between feeders by consuming a greater proportion of untreated food is defined as the discrimination threshold (DT). The DT occurred at sublethal concentrations in all 1:1 tests, with little mortality or reduction in food consumption. Little or no discrimination was observed in 9:1 tests, with mortality similar to the LC50 tests. The discrimination response in 5:5 tests was similar to the 1:1 tests for parathion and methiocarb, but with carbofuran the DT was higher than in the 1:1 test and higher mortality was observed. In all tests, mortality was inversely related to total food consumption. No relationship was found between mortality and the amount of active ingredient ingested/bird-day. Consequently, mortality was more a function of ability to locate untreated feeders than amount of chemical ingested. When alternative food choices exist, vulnerability to poisoning can be influenced by the number and relative abundance of those choices, as well as the bird's ability to detect the chemical.

Animals↗