Biological stress response terminology: Integrating the concepts of adaptive response and preconditioning stress within a hormetic dose-response framework.

Many biological subdisciplines that regularly assess dose-response relationships have identified an evolutionarily conserved process in which a low dose of a stressful stimulus activates an adaptive response that increases the resistance of the cell or organism to a moderate to severe level of stress. Due to a lack of frequent interaction among scientists in these many areas, there has emerged a broad range of terms that describe such dose-response relationships. This situation has become problematic because the different terms describe a family of similar biological responses (e.g., adaptive response, preconditioning, hormesis), adversely affecting interdisciplinary communication, and possibly even obscuring generalizable features and central biological concepts. With support from scientists in a broad range of disciplines, this article offers a set of recommendations we believe can achieve greater conceptual harmony in dose-response terminology, as well as better understanding and communication across the broad spectrum of biological disciplines.

Examining the risks and benefits of replacing traditional dose-response with hormesis.

In responding to Drs Calabrese and Baldwin's question, 'At what point, if ever, should hormesis be employed as the principal dose response default assumption in risk assessment?', we examined the benefits of replacing traditional dose-response with hormesis. In general, hormesis provides more complete useful information for risk assessment than does traditional dose-response. A major limitation of using hormesis as a default assumption in risk estimation is the difficulty of differentiating complex low-level hormetic responses from the placebo effect. A second limitation is that hormesis merely further defines one response. Most toxicoses have many responses. The most complete information takes all responses and their connections into account.

Genetically engineered corn rootworm resistance: potential for reduction of human health effects from pesticides.

OBJECTIVE AND METHODS: Insecticide use, grower preferences regarding genetically engineered (GE) corn resistant to corn rootworm (CRW), and the health effects of using various CRW insecticides (organophosphates, pyrethroids, fipronil and carbamates) are reviewed for current and future farm practices. RESULTS: Pest damage to corn has been reduced only one-third by insecticide applications. Health costs from insecticide use appear significant, but costs attributable to CRW control are not quantifiable from available data. Methods reducing health-related costs of insecticide-based CRW control should be evaluated. As a first step, organophosphate insecticide use has been reduced as they have high acute toxicity and risk of long-term neurological consequences. A second step is to use agents which more specifically target the CRW. CONCLUSION: Whereas current insecticides may be poisonous to many species of insects, birds, mammals and humans, a protein derived from Bacillus thurigiensis and produced in plants via genetic modification can target the specific insect of CRW (Coleoptra), sparing other insect and non-insect species from injury.

Characterization of a small plasmid (pMBCP) from bovine Pseudomonas pickettii that confers cadmium resistance.

This is the first report of isolation of Pseudomonas pickettii from a normal adult bovine duodenum. This organism was one of several bacteria isolated as part of a study to examine cadmium resistance genes (cad(r)) for use in generating transgenic plants to reclaim cadmium-contaminated soils in Kansas. P. pickettii containing a plasmid of 2.2kb (designated pMBCP) grew in Luria-Bertani broth and agar containing up to 800 microM of cadmium chloride and was resistant to 16 antibiotics. Curing the organism of plasmid revealed that antibiotic resistances were not plasmid-mediated. Low-level cadmium resistance was conferred by the plasmid because uncured organism grew significantly better (P<0.05) at 55 microM compared to cured organism. Both plasmid and chromosomal DNA were probed by DNA-DNA hybridization for the presence of known cadmium resistance genes (cadA, cadC, and cadD from Gram-positive (Staphylococcus aureus), but none were detected. The plasmid had one restriction site each for BamHI, PstI, SmaI, and XhoI; two sites each for HincII, SacI, and SphI; and multiple sites for AluI and XcmI. DNA sequence analyses of the cloned and original plasmids showed a GC content of greater than 60% and no homology to any published sequences in the GenBank, European Bioinformatics Institute, or Japanese Genome Net databases. The DNA sequence is contained in GenBank accession number AF144733. Thus, pMBCP offers low-level cadmium resistance to P. picketttii.

Pralidoxime hydrolysis of thiocholine esters.

Pralidoxime (2-PAM) hydrolyzes both acetylthiocholine and butytylthiocholine in an apparent first-order manner, with higher rates observed at pH 8.0 compared to those at pH 7.4. When the reaction is followed by the decrease in pH due to hydrolysis, pralidoxime hydrolyzes acetylthiocholine but not acetylcholine or succinylcholine. This implies that, while pralidoxime acts to reverse intoxication by organophosphate compounds due to the otherwise irreversible inhibition of acetylcholinesterase, it does not also supplement this detoxification by hydrolysis of the enzyme's substrate, acetylcholine.

Group learning improves case analysis in veterinary medicine.

INTRODUCTION: Group learning has become important to professional students in the healing sciences. Groups share factual and procedural resources to enhance their performances. METHODOLOGY: We investigated the extent to which students analyzing case-based evaluations as teams acquired an immediate performance advantage relative to those analyzing them as individuals and the extent to which group work on one problem led to better performance by individual students on related problems. We blinded written evaluations by randomly assigning numbers to groups of students and using removable tracers. Differences between groups and individuals were evaluated using Student's t statistic. Similar comparisons were evaluated by meta-analysis to determine overall trends. RESULTS: Students who analyzed evaluations as a group had an 8.5% performance advantage over those who analyzed them as individuals. When evaluations were divided into those asking questions related to treatment, differential diagnosis, and prognosis, specific performance advantages for groups relative to individuals were 8.9%, 5.9%, and 6.1% respectively. Students who had previously been trained by group evaluations had a 1.5% advantage relative to those who received their training as individuals. CONCLUSIONS: Answers by students analyzing evaluations as groups suggested a deeper understanding, in large part because of their improved ability to explain treatment and to conduct differential diagnosis. These improvements suggested limited abilities to use previous experience to improve present performance.