Applications of the Poly-K Statistical Test to Life-Time Cancer Bioassay Studies

The statistical analysis of cancer bioassay data has historically depended on the pathological determination of the experimental animal's cause of death. The poly-k statistical test has provided a method of statistical analysis of animal bioassay data without the need for cause of death information. The test has been shown to have good statistical properties in the typical 2-year cancer bioassay. However, while the poly-k test has been applied to chronic lifetime animal studies, it has not been formally evaluated with respect to the operating characteristics of this statistical test when applied to such studies. Thus, our objective is to assess the performance of the poly-k test for lifetime studies and to make comparisons with other tests. We observed in one recent lifetime study of the gasoline additive methyl tertiary butyl ether (MTBE) that the application of the poly-k test was not statistically robust. Simulation studies were subsequently conducted for a limited number of scenarios of lifetime cancer bioassays. These simulations showed that the poly-k test is not statistically robust for testing effect of increasing dose in some lifetime cancer studies.     

A decision-analytic framework for impact assessment part I: LCA and decision analysis

Life-cycle assessments (LCAs) are conducted to satisfy the aspiration of decision makers to consider the environment in their decision making. This paper reviews decision analysis and discusses how it can be used to structure the assessment and to integrate characterization and valuation. The decision analytic concepts of objectives (goals) and attributes (indicators of the degree to which an objective is achieved) are used to describe steps of the assessment of the entire impact chain. Decision analysis distinguishes among different types of objectives and attributes; it describes how these relate to each other. Impact indicators such as the Human Toxicity Potential are constructed attributes. A means-ends objectives network can show how the different constructed attributes relate to the objective of protecting the environment. As LCA takes disparate environmental impacts into account, it needs to assess their relative importance. Trade-off methods in decision analysis are grouped into utility theory and multicriteria decision aids; they have different advantages and disadvantages, but are all more sophisticated than simple weighting. The performance of the different trade-off methods has not yet been tested in an LCA context. In the second part of the paper, we present criteria for the development of characterization methods.     

A flight cylinder bioassay as a simple,effective quality control test for Cydia pomonella

Assessment of quality of the sterile male insects that are being mass‐reared for release in area‐wide integrated pest management programmes that include a sterile insect technique component is crucial for the success of these programmes. Routine monitoring of sterile male quality needs to be carried out both in the mass‐rearing facility and in the field. Simple bioassays that can be conducted in the laboratory and that would be surrogates for laborious field tests would be a very cost‐effective way of monitoring sterile male field performance. Simple flight cylinders were used to assess whether these could detect differences in quality of male codling moth Cydia pomonella. The number of male and female codling moths that flew out of the cylinders was influenced by cylinder diameter, cylinder height and number of hours following the initiation of the test. The flight cylinder bioassay was capable of detecting differences in quality of codling moths induced by irradiation when moths were shipped, but no differences were found in flight ability when the moths were not transported. The tests also confirmed that handling and shipment reduced quality more for irradiated than for non‐treated codling moth, and that insect quality was significantly influenced by larval rearing protocols. The flight cylinder bioassay was therefore successful in detecting differences in codling moth quality induced by various treatments that had been identified previously by more complex laboratory bioassays and field trials. Treatment differences were most likely detected when flight cylinders were 16 cm high.     

Bioassays of gonadotropins

Bioassays constitute a unique approach to determine the functional aspects of gonadotropins. Indeed, these highly complex glycoprotein hormones, including pituitary lutropin (LH) and follitropin (FSH), are heterogeneous in terms of both peptidic and carbohydrate moieties, and, as a consequence, the bioactivity of the different molecular forms often does not match their immunoreactivity. In this article, we review the different types of LH and FSH bioassays. Conventional methods for measuring FSH bioactivity are first described and include the in vivo Steelman and Pohley bioassay, the radioligand receptor assays (RRAs), the in vitro Sertoli cell bioassay, the in vitro granulosa cell bioassay, and the inhibin immunoassay. Recent methods based on cell lines transfected with cloned receptors, particularly the human FSH receptor, are then described. Methods for developing these assays are presented, and the advantages and disadvantages of the different bioassays are discussed.     

Comparison of laboratory and field bioassays of laboratory‐reared Cydia pomonella (Lepidoptera: Tortricidae) quality and field performance

Maximum production and fitness of insect species that are mass‐reared for biological control programmes such as the sterile insect technique (SIT) have benefitted from the employment of quality control and quality management. With a growing interest in the use of SIT as a tactic for the suppression/eradication of key lepidopteran pests, such as the codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae), there is a parallel interest in inexpensive bioassays that can accurately detect differences in insect quality and monitor insect field performance. In this study, we examined laboratory (mating and flight ability) bioassays and field (field cage and open field release) bioassays simultaneously to discern the ability of the different bioassays to predict quality and field performance of codling moths produced in a commercial mass‐rearing facility. Moth quality was degraded by different levels of radiation during the sterilization procedure. Both the laboratory flight bioassay and the field cage bioassay successfully detected quality and performance differences that were relevant to moth performance in the field. However, the study data suggest that the field cage bioassay was a better predictor of the daily performance of males that had been released in the orchard than the laboratory flight bioassay. Conversely, data suggest that the controlled climatic conditions of the laboratory allowed the flight cylinder bioassay to be more sensitive in detecting daily fluctuations in the quality of moths caused by factors within the mass‐rearing facility. Therefore, both laboratory and field bioassays may be required to provide feedback on quality and performance of mass‐reared moths in a SIT programme.     

Characterizing biological products and assessing comparability following manufacturing changes

Changes in production methods of a biological product may necessitate an assessment of comparability to ensure that these manufacturing changes have not affected the safety, identity, purity, or efficacy of the product. Depending on the nature of the protein or the change, this assessment consists of a hierarchy of sequential tests in analytical testing, preclinical animal studies and clinical studies. Differences in analytical test results between pre- and post-change products may require functional testing to establish the biological or clinical significance of the observed difference. An underlying principle of comparability is that under certain conditions, protein products may be considered comparable on the basis of analytical testing results alone. However, the ability to compare biological materials is solely dependent on the tests used, since no single analytical method is able to compare every aspect of protein structure or function. The advantages and disadvantages of any given method depends on the protein property being characterized.     

Phytoplankton bioassays for evaluating toxicity of in situ sediment contaminants

Routine bulk chemical characterization of sediments does not provide useful information on toxicity of sediment bound contaminants. This study reviewed and evaluated the utility of phytoplankton bioassays for evaluation of toxicity of sediment bound contaminants, including state-of-the-art techniques. Several techniques such as Algal Fractionation Bioassays, microcomputer-based toxicity testing and in situ bioassays including plankton cages have been developed and successfully applied in our research at various contaminated sites in the St. Lawrence Great Lakes. These bioassay techniques are sensitive, rapid and inexpensive for screening contaminants. The use and application of such techniques, based on bioavailability and physiological response of micro-organisms, are essential for the detection of environmental perturbations of an ecosystem. Such an early warning system will facilitate the preservation and rehabilitation of the Great Lakes.     

The need for standardised broad scale bioassay testing: A case study using the red alga Laurencia rigida

Two major problems associated with biofouling studies are the lack of broad scale testing and failure to use consistent standards among different assays or studies. To address these issues the activity of two biologically active natural products, elatol and deschloroelatol, isolated from the marine red alga Laurencia rigida, and three commonly used biocides, Nopcocide N-96?, Irgarol 1051? and Sea-Nine 211?, was compared, in a broad spectrum of bioassays. The activity of the different compounds varied substantially among different bioassay tests. Elatol and deschloroelatol had a narrow range of activity with strongest effects against invertebrate larvae. Both compounds were highly toxic. However, neither compound had strong activity against marine bacteria or the common epiphyte Ulva lactuca. Irgarol 1051 also had a narrow range of activity, only affecting algal settlement strongly. Nopcocide N-96 and Sea-Nine 211 had moderate to strong activity across the spectrum of bioassays, viz. growth of marine bacteria (Vibrio fischeri, Serratia sp.), inhibition of settlement of macroalgae (Ulva lactuca), toxicity (Balanus amphitrite), and inhibition of settlement of invertebrate larvae (Balanus amphitrite, Bugula neritina). Based on the results it is proposed that Sea-Nine 211, because of its broad spectrum activity, be used as a standard for comparative assessments of the antifouling activity of marine natural products and analogues.     

Use of a multiple addition bioassay to determine limiting nutrients in eagle lake,California

This investigation uses anin vitro enrichment bioassay (in which all essential nutrients except one are added to each culture) to determine which nutrients are important to algal growth in Eagle Lake. The technique was developed when it was discovered that addition of individual nutrients produced little if any growth response. Laboratory bioassays correlated well with comparative studies in the lake. A great deal of variation was found throughout the year but P, N, Fe, and S were found to be limiting at one time or another. The north and south basins of the lake, which differ in morphometry, were also found to differ in the intensity spectrum of limitation. While P was the most important nutrient in both basins, the other nutrients were more limiting in the north basin than the south, and Fe, which was least limiting in the south, was very important in the north. The multiple enrichment bioassay has several advantages over other bioassays. Supported in part by Research Corporation     

A Statistical Evaluation of Sediment Quality Triad Benthic Community Measurements in PAH-Impacted Sediments at a Manufactured Gas Plant Site along the Hudson River

The sediment quality triad (SQT) assumes that three measurements (sediment chemistry, laboratory bioassay, and benthic macroinvertebrate counts) comprise an independent assessment of impact, which when integrated using a weight-of-evidence approach provides a comprehensive assessment of risk. An SQT assessment was conducted on 41 sediment samples collected adjacent to a manufactured gas plant site on the freshwater reach of the Hudson River in New York State. The assessment shows that the benthic macroinvertebrate data did not correlate with either sediment or pore water polycyclic aromatic hydrocarbon (PAH) concentrations, nor did these data show consistent relationships to the results of laboratory bioassay testing (Hyalella azteca 28-day survival or biomass). The benthic community across the site and reference areas was comprised of few taxa, all of which were pollution-tolerant organisms with tolerance values greater than or equal to five. Only in significantly impacted sediment samples with PAH concentrations in the thousands of milligrams per kilogram, pore water concentrations above 100 toxic units, and visible non-aqueous phase liquid present in the sample did the benthic macroinvertebrate data show a response. In contrast, sediment and pore water PAH measurements and H. azteca toxicity testing provided consistent interpretation of impact. These results illustrate that benthic macroinvertebrate data may contain less information value and be a more challenging line of evidence to interpret in triad studies conducted in certain ecological settings; in this case, a large-order river with a relatively depauperate benthic community dominated by species tolerant of PAHs.     

Neurological evaluation of chronic headache patients: Is laboratory testing always necessary?

A review of records was conducted to examine the utility of doing routine laboratory testing (EEG and skull X rays) versus testing at the discretion of the attending neurologist on patients presenting for the nonpharmacological treatment of chronic headache. A total of 278 patients underwent neurological evaluation as part of a routine assessment prior to beginning self-regulatory treatment for headache. The first 112 subjects received routine laboratory tests of EEG and skull X-ray films. The second set of 166 subjects received laboratory tests only when deemed necessary by the neurologist. The rate of abnormal EEG in chronic headache sufferers was no greater than that found in the normal population, and only one or two potentially serious abnormalities were found on any laboratory test. A higher rate of abnormality was found when the CT scan was used in conjunction with clinical judgment. The majority of clients with abnormal laboratory tests (most of which were mildly abnormal) still saw substantial headache reduction with self-regulatory treatment for chronic headache. The authors suggest that routine laboratory testing may not be necessary and should be left to the discretion of a qualified neurologist.This research was supported in part by grants from NINCDS, NS-15235 and NS-23440.     

Neurological evaluation of chronic headache patients: is laboratory testing always necessary?

A review of records was conducted to examine the utility of doing routine laboratory testing (EEG and skull X rays) versus testing at the discretion of the attending neurologist on patients presenting for the nonpharmacological treatment of chronic headache. A total of 278 patients underwent neurological evaluation as part of a routine assessment prior to beginning self-regulatory treatment for headache. The first 112 subjects received routine laboratory tests of EEG and skull X-ray films. The second set of 166 subjects received laboratory tests only when deemed necessary by the neurologist. The rate of abnormal EEG in chronic headache sufferers was no greater than that found in the normal population, and only one or two potentially serious abnormalities were found on any laboratory test. A higher rate of abnormality was found when the CT scan was used in conjunction with clinical judgment. The majority of clients with abnormal laboratory tests (most of which were mildly abnormal) still saw substantial headache reduction with self-regulatory treatment for chronic headache. The authors suggest that routine laboratory testing may not be necessary and should be left to the discretion of a qualified neurologist.     

Regulatory agency consideration of pharmacogenomics

This article discusses the current ambiguous state of federal regulatory agency control over pharmacogenomic testing, a subset of genetic testing that combines information about genetic variability with pharmacology in order to improve drug recommendations. An analysis of the common three terms used to evaluate regulation of pharmacogenomic testing: research validity, clinical validity, and clinical utility, followed by a case study involving U. S. Food and Drug Administration (FDA) regulation of laboratory developed tests, illustrates the present gap in pharmacogenomic oversight. The existing agency overlap in regulating pharmacogenomic testing leads to unclear or even contradictory authoritative advice.     

Increased Risk Proneness or Social Withdrawal? The Effects of Shortened Life Expectancy on the Expression of Rescue Behavior in Workers of the ant <Emphasis Type="Italic">Formica cinerea</Emphasis> (Hymenoptera: Formicidae)

In social insects behavioral consequences of shortened life expectancy include, among others, increased risk proneness and social withdrawal. We investigated the impact of experimental shortening of life expectancy of foragers of the ant Formica cinerea achieved by their exposure to carbon dioxide on the expression of rescue behavior, risky pro-social behavior, tested by means of two bioassays during which a single worker (rescuer) was confronted with a nestmate (victim) attacked by a predator (antlion larva capture bioassay) or immobilized by an artificial snare (entrapment bioassay). Efficacy of carbon dioxide poisoning in shortening life expectancy was confirmed by the analysis of ant mortality. Rescue behavior observed during behavioral tests involved digging around the victim, transport of the sand covering the victim, pulling the limbs/antennae/mandibles of the victim, direct attack on the antlion (in antlion larva capture tests), and snare biting (in entrapment tests). The rate of occurrence of rescue behavior was lower in ants with shortened life expectancy, but that effect was significant only in the case of the entrapment bioassay. Similarly, only in the case of the entrapment bioassay ants with shortened life expectancy displayed rescue behavior after a longer latency and devoted less time to that behavior than ants from the control groups. Our results demonstrated that in ant workers shortened life expectancy may lead to reduced propensity for rescue behavior, most probably as an element of the social withdrawal syndrome that had already been described in several studies on behavior of moribund ants and honeybees.     

Pathogenicity and virulence

Invertebrate pathologists have multiple definitions for the terms pathogenicity and virulence, and these definitions vary across disciplines that focus on host-pathogen interactions. We surveyed various literatures, including plant pathology, invertebrate pathology, evolutionary biology, and medicine, and found most define pathogenicity as the broader term, which incorporates virulence. Virulence is seen as the severity of disease manifestation that can only be measured in infected individuals. These definitions readily apply to both lethal and non-lethal diseases. Invertebrate pathologists commonly use dose-response bioassays to estimate LD(50) or LC(50) (dose or concentration needed to kill 50% of hosts exposed). These bioassays measure pathogenicity if the bioassay includes a transmission component, and measure virulence if the bioassay is measured in infected individuals only. Another common bioassay estimate is LT(50) (median time to death of infected hosts), which is a measure of virulence as long as survivors are not included in its calculation.     

Simple in vivo bioassay without radioisotopes for recombinant human erythropoietins.

A simple in vivo bioassay suitable for routine testing of quality control of recombinant human erythropoietin (rHuEPO) analogues was developed. The assay took four days, normal mice were used and radioactive compounds were not needed. EPO activity was measured by the increased number of some part of reticulocytes which increased specifically and dose-dependently by the injection of rHuEPO. They were considered to be mostly immature reticulocytes and were counted as the residual particles from blood cells after treatment with a hemolysing reagent. These particles could be counted by conventional automated microcell counters. The assay procedure was simple and easy. The sensitivity, reliability and reproducibility of this method were acceptable for routine in vivo bioassay of rHuEPOs. This method was economical, and can be used instead of the existing bioassays for rHuEPOs.     

In vitro bioassay methods for laboratory screening of novel mosquito repellents

Repellents are highly effective in preventing humans from being bitten by mosquitoes and other blood‐feeding insects. Here we provide an overview of the representative in vitro bioassays for the laboratory testing of these agents. Currently, potential repellents are mostly evaluated on human skin, using the arm‐in‐cage method. However, for the testing of large numbers of chemicals for mosquito repellent activity, several in vitro bioassays have been established. Based on their components, as described in the recent literature, these can be categorized: (i) the natural tendency system; (ii) the membrane plus blood system; (iii) the skin plus attractants system; and (iv) the host plus netting system. The major advantages and disadvantages of these bioassays are discussed with the aim of establishing reliable and practical methods for discovering novel mosquito repellents.     

Multi-criteria evaluation of multi-purpose stand treatment programmes for Finnish boreal forests under changing climate

The aim of this study is determine the potential of multiple-criteria analysis (MCA) methodology to assess the utility of different multi-objective stand treatment programmes, in the boreal forest. Simulations over a planning period of 100 years under current and changing climate scenarios by a physiological growth model provided input data for the stochastic multi-criteria analysis of forest management alternatives. Expected utility with regard to a set of objectives was estimated with an additive utility model. Timber production, carbon sequestration and biodiversity were considered as partial objectives; these in term were represented by decision criteria. The weights of partial objectives and criteria were subjected to uncertainty due to missing exact stakeholder preference information. Generic probability distributions for individual weights were defined based on qualitative information. Alternative stand treatment programmes with regard to the decision criteria were evaluated by means of linear preference functions. In a Monte Carlo analysis the utility model was employed to evaluate eight stand treatment programmes for their performance regarding the management objectives. The effect of climate change on utility of stand treatment programmes was examined also as an important factor. Over two sites and three tree species just two out of eight stand treatment programmes analysed in this study were able to dominate the set of alternatives; namely the unthinned scenario and the highest increase in thinning thresholds scenario (UT(0, 0) and BT(+30, +30)) in which stocking was kept at higher level compared to the currently recommended guidelines for site and species. Reducing uncertainty in the utility model by assuming accurate weights for the decision criteria did not show large changes neither in expected utility nor in the ranking of alternatives. Ignoring necessary revisions of how the forest is to be managed in the future might potentially result in losses, not only for timber production but also for benefits such as carbon sequestration and other amenities including biodiversity.     

The application of bioassays in the resolution of environmental problems; past,present and future

Literature on bioassays for freshwater systems has been reviewed (between 1979 and 1987) and classified into studies concerned with prediction and assessment and, within these categories, into studies concerned with single- and multi-species bioassays. Changing trends in the response criteria and types of organisms used in the predictive tests are judged against results from a similar review carried out in 1979. This leads to the conclusion that though there may have been changes in detail, bioassays have remained surprisingly unchanged in general features over this time. The relative merits of, and relationship between single- and multi-species studies for both predicting and assessing the biological impact of toxicants are discussed. The conclusion is that some bioassays have more severe problems than others, but a concern with all of them is that responses observed in particular systems may not be relevant in general. The possibility of developing a general theoretical infrastructure for bioassays that addresses this problem is considered.     

Enantioselective analytical methods in pharmacokinetics with specific reference to genetic polymorphic metabolism

The new trend towards developing enantiospecific drugs has increased the interest in enantiospecific pharmacokinetics of chiral drugs, mainly in the case where only one of the two enantiomers is responsible for the pharmacological activity. Enantiospecific bioassays are also useful in investigating the pharmacokinetic behaviour of the two enantiomers when a given drug is marketed as racemate. The stability of the stereogenic centre in vitro and in vivo, as far as unidirectional and bidirectional inversions are concerned, is another reason for requiring stereospecific assay and bioassay. These assays are often complicated in order to achieve quantification, mainly for in vivo measurements, which are often in the low pg/ml range. This paper considers the enantiospecific bioassays, the methods and approaches used, the need for chemical derivatization, and the difficulties involved. It includes a specific discussion for the genetic polymorphic metabolism involving stereogenic centres.