Linking frass and insect phenology to optimize annual forest defoliation estimation.

It is often logistically impractical to measure forest defoliation events in the field due to seasonal variability in larval feeding phenology (e.g., start, peak, and end) in any given year. As such, field data collections are either incomplete or at coarse temporal resolutions, both of which result in inaccurate estimation of annual defoliation (frass or foliage loss). Using Choristoneura pinus F. and Lymantria dispar dispar L., we present a novel approach that leverages a weather-driven insect simulation model (BioSIM) and defoliation field data. Our approach includes optimization of a weighting parameter (w) for each instar and imputation of defoliation. Results show a negative skew in this weighting parameter, where the second to last instar in a season exhibits the maximum consumption and provides better estimates of annual frass and foliage biomass loss where sampling data gaps exist. Respective cross-validation RMSE (and normalized RMSE) results for C. pinus and L. dispar dispar are 77.53 kg·ha-1 (0.16) and 38.24 kg·ha-1 (0.02) for frass and 74.85 kg·ha-1 (0.10) and 47.77 kg·ha-1 (0.02) for foliage biomass loss imputation. Our method provides better estimates for ecosystem studies that leverage remote sensing data to scale defoliation rates from the field to broader landscapes and regions.•Utilize fine temporal resolution insect life cycle data derived from weather-driven insect simulation model (BioSIM) to bridge critical gaps in coarse temporal resolution defoliation field data.•Fitting distributions to optimize the instar weighting parameter (w) and impute frass and foliage biomass loss based on a cumulative density function (CDF).•Enables accurate estimation of annual defoliation impacts on ecosystems across multiple insect taxa that exhibit distinct but seasonally variable feeding phenology.

Defining Significant Events for Neonatal and Pediatric Transport: Results of a Combined Delphi and Consensus Meeting Process.

Objective To develop standardized definitions for a list of indicators that represent significant events during pediatric transport, which were previously identified by a national Delphi study. Methods We designed a three-phase consensus process that applied Delphi methodology to a combination of electronic questionnaires and a live consensus meeting. Results Thirty-one pediatric transport experts evaluated a total of 59 indicators. Twenty-four indicators represented events or interventions that did not require definition. One indicator was removed from the list. Definitions for the remaining 34 indicators were developed. Conclusion This standardized indicator list is intended for application to quality improvement and clinical research initiatives.

A history of blood glucose meters and their role in self-monitoring of diabetes mellitus.

Self-monitoring blood glucose (SMBG) systems have the potential to play an important role in the management of diabetes and in the reduction of risk of serious secondary clinical complications. This review describes the transition from simple urine sugar screening tests to sophisticated meter and reagent strip systems to monitor blood glucose. Significant developments in design and technology over the past four decades are described since the first meter was introduced in 1970. Factors that have influenced this evolution and the challenges to improve analytical performance are discussed. Current issues in the role of SMBG from the clinical, patient and manufacturer perspectives, notably adherence, costs and regulations, are also considered.

Liver hypertrophy: a review of adaptive (adverse and non-adverse) changes--conclusions from the 3rd International ESTP Expert Workshop.

Preclinical toxicity studies have demonstrated that exposure of laboratory animals to liver enzyme inducers during preclinical safety assessment results in a signature of toxicological changes characterized by an increase in liver weight, hepatocellular hypertrophy, cell proliferation, and, frequently in long-term (life-time) studies, hepatocarcinogenesis. Recent advances over the last decade have revealed that for many xenobiotics, these changes may be induced through a common mechanism of action involving activation of the nuclear hormone receptors CAR, PXR, or PPARα. The generation of genetically engineered mice that express altered versions of these nuclear hormone receptors, together with other avenues of investigation, have now demonstrated that sensitivity to many of these effects is rodent-specific. These data are consistent with the available epidemiological and empirical human evidence and lend support to the scientific opinion that these changes have little relevance to man. The ESTP therefore convened an international panel of experts to debate the evidence in order to more clearly define for toxicologic pathologists what is considered adverse in the context of hepatocellular hypertrophy. The results of this workshop concluded that hepatomegaly as a consequence of hepatocellular hypertrophy without histologic or clinical pathology alterations indicative of liver toxicity was considered an adaptive and a non-adverse reaction. This conclusion should normally be reached by an integrative weight of evidence approach.

Assessing proliferation, cell-cycle arrest and apoptotic end points in human buccal punch biopsies for use as pharmacodynamic biomarkers in drug development.

Easily accessible normal tissues expressing the same molecular site(s) of drug action as malignant tissue offer an enhanced potential for early proof of anticancer drug mechanism and estimation of the biologically effective dose. Studies were undertaken in healthy male volunteers to assess the tolerability of single and multiple (four in 24 h) 3 mm punch biopsies of the buccal mucosa, and to determine the feasibility of detecting and quantifying a range of proliferation, cell-cycle arrest and apoptosis markers by immunohistochemistry (IHC) for use as potential pharmacodynamic (PD) end points. The biopsy procedure was well tolerated with 100% of volunteers stating that they would undergo single (n = 10) and multiple (n = 12) biopsies again. Total retinoblastoma protein (pRb), phosphorylated pRb (phospho-pRb), total p27, phosphorylated p27 (phospho-p27), phosphorylated-histone H3 (phospho-HH3), p21, p53, Cyclin A, Cyclin E, Ki67 all produced good signal detection, but M30, cleaved caspase 3 and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling did not. Total pRb, phospho-pRb, total p27 and phospho-p27 were quantified further in a multiple biopsy study to allow components of variability to be addressed to inform future sizing decisions on intervention studies. Neither site of biopsy within the oral cavity, nor the nominal time of biopsy had any significant impact on any of the four markers expression levels. Inter- and intrasubject coefficients of variation (CVs) that could be used to size future intervention studies for pRb, phospho-pRb, total p27 and phospho-p27 were 14, 19, 18 and 16%; and 18, 29, 25 and 19%, respectively. In conclusion, quantitation of such markers in 3 mm buccal punch biopsies would be suitable to explore as PD end points within intervention studies of drugs acting on these pathways.

Plucked human hair as a tissue in which to assess pharmacodynamic end points during drug development studies.

We have demonstrated the feasibility of detecting and quantifying six cell-cycle-related nuclear markers (Ki67, pRb, p27, phospho-p27 (phosphorylated p27), phospho-pRb (phosphorylated pRb), phospho-HH3 (phosphorylated histone H3)) in plucked human scalp and eyebrow hair. Estimates of the proportion of plucked hairs that are lost or damaged during processing plus the intra- and intersubject variability of each nuclear marker with these techniques are provided to inform sizing decisions for intervention studies with drugs potentially impacting on these markers in the future.

One hundred years of virology: a chief's perspective.

The ubiquitous nature of viruses has had its impact throughout the living world. Virus disease can be found in higher animals, birds, plants, arthropods, protozoa and bacteria. Viruses are no modern phenomenon, although it is only in the last 50 or so years that a fuller knowledge of their biological, chemical and physical properties has emerged. This short account recalls the development of human virology in particular, from the first discovery of a 'filterable virus' in 1892 to the spectacular technological breakthroughs during the 1950's and 1960's, leading to the molecular virology of today. This account was written to accompany an exhibition of artefacts displayed during the IBMS Congress in Birmingham in September 2001.

The role of cytochromes P-450 in styrene induced pulmonary toxicity and carcinogenicity.

Exposure of CD-1 mice to atmospheres of 40 and 160 ppm styrene, daily for up to 10 days, caused pulmonary toxicity characterised by focal loss of cytoplasm and focal crowding of non-ciliated Clara cells, particularly in the terminal bronchiolar region. The toxicity was accompanied by an increase in cell replication rates in terminal and large bronchioles of mice exposed for 3 days or longer. The toxicity and increased cell replication were no longer apparent after a 2-day break in exposure, but re-occurred when exposure was resumed. Similar effects were seen in mice given oral doses of 10, 100 or 200 mg/kg styrene, daily for 5 days. Increases in cell replication rates were seen in the terminal bronchioles in mice dosed with 100 and 200 mg/kg styrene, but not 10 mg/kg. Toxicity was limited to 3 to 10 animals in the 200 mg/kg group. Neither morphological nor cell proliferation effects were seen in the alveolar region of the mouse lung in any of these studies, nor were any effects observed in the lungs of CD rats exposed to 500 ppm styrene for up to 10 days. The pulmonary toxicity and increased cell division seen in mice, but not rats, correlates with the known species differences in pulmonary carcinogenicity of styrene, suggesting that the acute and chronic responses are causally related. 5-Phenyl-1-pentyne was shown to inhibit the pulmonary cytochrome P-450 metabolism of styrene in vivo. Cell replication rates in the lungs of mice treated with this inhibitor and exposed to styrene were comparable with controls demonstrating that the pulmonary effects of styrene on the mouse lung are caused by a metabolite of styrene, probably styrene oxide. The risks associated with exposure to styrene appear to correlate well with the metabolic capacity of the lung.

The functions of cytokines and their uses in toxicology.

Cytokines are critical controllers of cell, and hence tissue, growth, migration, development and differentiation. The family includes the inflammatory cytokines such as the interleukins and interferons, growth factors such as epidermal and hepatocyte growth factor and chemokines such as the macrophage inflammatory proteins, MIP-1alpha and MIP-1beta. They do not include the peptide and steroid hormones of the endocrine system. Cytokines have important roles in chemically induced tissue damage repair, in cancer development and progression, in the control of cell replication and apoptosis, and in the modulation of immune reactions such as sensitization. They have the potential for being sensitive markers of chemically induced perturbations in function but from a toxicological point of view, the detection of cytokine changes in the whole animal is limited by the fact that they are locally released, with plasma measures being generally unreliable or irrelevant, and they have short half lives which require precise timing to detect. Even where methodology is adequate the interpretation of the downstream effects of high, local concentrations of a particular cytokine is problematic because of their interdependence and the pleiotropism of their action. A range of techniques exist for their measurement including those dependent upon antibodies specific for the respective cytokines, but with the introduction of genomic and proteomic technology, a more complete study of cytokine changes occurring under the influence of chemical toxicity should be possible. Their further study, as markers of chemical toxicity, will undoubtedly lead to a greater understanding of how synthetic molecules perturb normal cell biology and if, and how, this can be avoided by more intuitive molecular design in the future.

Methyl methacrylate toxicity in rat nasal epithelium: studies of the mechanism of action and comparisons between species.

Female F344 rats exposed to 200 ppm methyl methacrylate for 6 h developed a lesion in the nasal olfactory epithelium which was characterised by degeneration and atrophy. The severity of the lesion was markedly reduced by pre-treatment of the rats with an intraperitoneal dose of 100 mg/kg bis-(p-nitrophenyl)phosphate, an inhibitor of carboxylesterase enzymes, thus demonstrating that the lesion is caused by the carboxylesterase mediated metabolism of methyl methacrylate to methacrylic acid, an irritant and corrosive metabolite. The distribution of the carboxylesterases in nasal tissues has been investigated and the metabolism of methyl methacrylate to methacrylic acid has been compared in rat, hamster and human nasal tissue fractions in vitro. Histocytochemistry showed that the carboxylesterases are heavily localised in the sustentacular cells and Bowman's glands of the rat olfactory region, but are more generally distributed in human olfactory epithelium. Consistent with this, the enzyme activity in all three species was higher in fractions prepared from olfactory tissue than from respiratory tissue, 3-fold in rat and human and 12-fold in the hamster. The maximum rates (V(max)) of metabolism in rat and hamster olfactory tissue fractions were comparable, whereas those in human olfactory tissue fractions were at least 13-fold lower. The rate of metabolism in rat olfactory tissue was also comparable to that in rat liver whereas in humans, the rate in olfactory tissue was 500-fold lower than that in the liver. In respiratory tissues, the rate in humans was at least 6-fold lower than that in the rat. These results suggest that humans are significantly less sensitive than rodents to the nasal toxicity of methyl methacrylate.

Sound-level measurements and calculations of safe noise dosage during EPI at 3 T.

This paper describes systematic methods for measuring and controlling sound levels within a magnetic resonance scanner. The methods are illustrated by application to the acoustic noise generated by a 3 T scanner during echoplanar imaging (EPI). Across five measurement sessions, sound pressure levels at the center of the head gradient coil ranged from 122 to 131 dB SPL [123 to 132 dB(A)]. For protection against damaging noise exposure, UK and US industrial guidelines stipulate that the maximum permitted daily noise dosage is equivalent to 90 dB(A) for 8 hours, where noise dosage is a function of the level of an acoustic signal and the length of exposure to it. Without hearing protection, this equivalent level would be exceeded by less than 5 seconds of exposure to the measured levels of scanner acoustic noise. These findings highlight the importance of noise reduction and hearing protection for those exposed to the acoustic noise generated during EPI.

Estradiol-type activity of coumestrol in mature and immature ovariectomized rat uterotrophic assays.

Makaverich et al. [Environ Health Perspect 103:574-581 (1995)] reported that the uterotrophic activity of the phytoestrogen coumestrol in the immature ovariectomized rat was atypical in that it was not associated with increased uterine hyperplasia and DNA content. We previously reported that coumestrol gave a typical estradiol-type uterotrophic response in the immature intact rat, yielding increases in uterine epithelial cell height, glandular formation, cell labeling, and DNA content. These papers did not answer the question of whether there is a basic difference between the ovariectomized and the intact rat uterotrophic assays. In this paper, we report that coumestrol gives a typical estradiol-type uterotrophic response in uterotrophic assays using immature intact, immature ovariectomized, and mature ovariectomized rats. We concluded that the uterotrophic activity of coumestrol is typical of the natural estrogen estradiol.

Cell death and cell proliferation in the control of normal and neoplastic tissue growth.

The development of reliable methodology for the assessment of rates of cell replication and cell death has enabled the study of how these 2 fundamentally opposed processes work to form and maintain tissue and to remodel tissue following diseases resulting in cell loss. The balance between these 2 processes and the consequences of an imbalance are fundamental to a clearer understanding of how hyperplasia and neoplasia develop in tissues under the influence of chemicals and drugs. An understanding of the changes that occur in target organs and tissues following chemical or drug exposure has enabled a better understanding of the mechanism by which these chemicals are able to induce cancer after prolonged exposure. Studies of the control of cell replication and the changes that occur following drug exposure have defined 2 types of response, 1 in which the cell replicative response is sustained and the other in which the cell replicative response is transient and occurs during the first few days of exposure. Although regulatory and scientific opinion appears ready to accept sustained cell replicative processes as an increased risk factor in the development of cancer, the role played by transient increases in cell replication remains unclear. Concurrent events in target organs following treatment with chemicals that induce transient increases in cell replication have revealed that the rates of apoptosis are suppressed at the same time as the cell replication levels are induced. Additional evidence suggests that growth and antigrowth factors are central in controlling these responses. Escape from the regulatory action of these factors is postulated to be one of the ways in which nongenotoxic carcinogenic chemicals, such as the peroxisome proliferators and sodium phenobarbitone, may induce cancer, with apoptosis playing a key role in the process.

Time-course of the auditory BOLD response to scanner noise.

It is a concern for auditory fMRI studies that acoustic noise generated by the scanner produces an auditory response that can confound stimulus-induced activation. To establish how to minimize this problem, the present study mapped the time-course of the auditory response to a burst of acoustic scanner noise by employing a single-event method. Recorded bursts of scanner noise were interspersed with clustered-volume acquisitions at a range of stimulus-to-imaging delays to map the response with a temporal resolution of 1 sec. There were strong responses (1.5% signal change) to scanner noise in primary and secondary auditory cortex. In both cortical areas, the mean response rose to a peak by 4-5 sec after stimulus onset and decayed after a further 5-8 sec. The time course indicates that noise contamination in auditory fMRI can be substantially reduced by using a 9-12-sec repetition time, thus maximizing the dynamic range available for displaying the response to acoustical stimuli of interest.

Effects of p-nonylphenol (NP) and diethylstilboestrol (DES) on the Alderley Park (Alpk) rat: comparison of mammary gland and uterus sensitivity following oral gavage or implanted mini-pumps.

An earlier report by Colerangle and Roy indicated that administration of p-nonylphenol (NP) to Noble rats, via subcutaneously implanted mini-pumps at estimated doses of 53.2 and 0.073 mg kg(-1) day(-1) for 11 days, led to proliferation of the mammary gland. Those results indicated a ca. 600-fold enhancement in assay sensitivity to NP over that of the standard 3-day rat uterotrophic assay. The potential importance of these observations led us to repeat the experiments in the Noble rat, as described earlier. Although our earlier results confirmed the reported effects of diethylstilboestrol (DES) on the mammary gland of Noble rats, we found no effects with NP. The present report extends our investigations of the effects of NP and DES on the mammary gland and uterus of other rat strains using both oral dosing and exposure via mini-pumps. The 3-day oral uterotrophic assay responses to NP were similar for immature Alderly Park (Alpk; Wistar-derived) and immature Sprague-Dawley rats. Likewise, oral administration of NP to ovariectomized Alpk rats for 11 days gave responses of a similar magnitude to those seen in the 3-day immature assays and in earlier 3-and 11-day oral assays conducted using Noble rats. Administration of NP via mini-pumps to ovariectomized Alpk rats, at the implant doses employed by Colerangle and Roy, gave a negative uterotrophic response. The highest achieved dose levels of NP in the implant experiment (27 mg kg(-1) day(-1)) were lower than in the above assays and the negative response was therefore consistent with the previously defined minimum detection level for NP in the uterotrophic assay of ca. 40 mg kg(-1) day(-1) day(-1). It is concluded that the uterotrophic activity of NP is independent of the strain of rat, the duration of dosing and the route of exposure. Two mammary gland studies were conducted on NP and DES in the Alpk rat. In the first study (a repeat of the techniques used in earlier studies with the Noble rat), NP was administered via mini-pumps (achieved doses of 0.052 and 37.4 mg kg(-1) day(-3) NP) and produced no effect on mammary gland development, whereas DES gave the expected trophic response. In the second mammary gland study, NP was administered orally to Alpk rats at 100 mg kg(-1) day(-1) for 11 days (a dose that produced a positive uterotrophic response in ovariectomized rats). In this experiment, DES, and to a lesser extent NP, increased mammary gland differentiation and cell proliferation. The present studies have demonstrated that the rat mammary gland responds predictably to oestrogenic stimulation but does not show increased sensitivity to oestrogens when compared to the rat uterus. It is also concluded that the minimum detection level for oestrogenic responses of NP in rodents, following oral, dietary and implant routes of exposure, is ca. 40 mg kg(-1) day(-1).

Quantitative analysis of the lobular distribution of S-phase in rat liver following dietary administration of di(2-ethylhexyl)phthalate.

A simple image-analysis method is described, whereby the distribution of hepatocytes that have entered S-phase, as distinguished by the incorporation of bromodeoxyuridine, can be related to the position of the central and portal veins of the hepatic lobule. Hepatocyte S-phase was induced in the livers of male and female F344 rats by administration of di(2-ethylhexyl)phthalate (DEHP) in the diet for 7 days at 2 dose levels, and these livers were used to develop the procedure. The distributions of the S-phase between control and DEHP-treated livers were compared using statistical techniques. The results showed notable differences in the distribution of S-phase between male and female rats as well as limited dose-related effects.

Comparative activities of p-nonylphenol and diethylstilbestrol in noble rat mammary gland and uterotrophic assays.

Colerangle and Roy (1996, Endocrine 4, 115-122) have described the apparent ability of both diethylstilbestrol (DES) and p-nonylphenol (NP) to cause extensive cell proliferation and lobular development in the mammary glands of young adult Noble rats. The chemicals were administered over 11 days via subcutaneously implanted minipumps. The dose level of DES used (0.076 mg/kg/day) was about 70 times higher than its minimum detection level in rodent uterotrophic and reproductive toxicology studies. In contrast, the lowest active dose level of NP (0.073 mg/kg/day) in the Noble rat mammary gland study was about 600 times lower than its minimum detection level in rat uterotrophic and multigeneration studies. The apparent enhanced sensitivity of the Noble rat mammary gland to the estrogenic activity of NP was considered worthy of further study. Ovariectomized Noble rat uterotrophic assays with NP (minimum detection level approximately 40 mg/kg/day, 3 or 11 days, oral gavage) revealed similar assay sensitivity to that observed for earlier immature and ovariectomized Alderley Park (AP) rat uterotrophic assays of this chemical. The response of the ovariectomized Noble rat uterotrophic assay to DES and estradiol was also as expected from earlier immature AP rat assays. It is concluded that the general sensitivity to estrogens of the Noble rat and the AP rat is similar. A repeat of the Noble rat mammary gland study with DES (11 x 0.076 mg/kg/day) and NP (11 x either 0.073 or 53.2 mg/kg/day), as originally reported by Colerangle and Roy (1996), revealed a strong positive response to DES and no response to NP. It is concluded that the minimum detection level of NP as a weakly estrogenic material in the rat should be based on the results of rat uterotrophic and multigeneration studies and therefore be set at approximately 40 mg/kg/day. It is also concluded that induced S-phase in the rodent mammary gland is best monitored using BRDU, as opposed to PCNA staining, and that use of subcutaneously implanted minipumps/pellets is inappropriate for risk/hazard assessment studies of chemicals already established as estrogenic in vitro and in vivo, as are NP and DES.

The reproductive toxicity of molinate and metabolites to the male rat: effects on testosterone and sperm morphology.

Molinate causes an impairment in reproductive capability in the male rat. Administration of molinate to rats (40 mg/kg/day for 7 days) caused a distinctive sperm lesion. At higher doses of molinate (140 mg/kg for 7 days) this lesion was accompanied by morphological changes to the testis that were consistent with a delayed release of the late spermatids to the seminiferous tubular lumen, a process controlled by the release of testosterone. In accordance with this, molinate (>/=40 mg/kg) caused a marked decrease in the concentration of circulating and testicular testosterone. The Leydig cells of the testis appear to be the primary target site in that radiolabel from [3H]molinate specifically localized within this cell type. In addition, esterase activity in the Leydig cells was inhibited following molinate administration. In vitro, molinate is a poor inhibitor of esterase activity, whereas molinate sulfoxide, a major metabolite of molinate in rats, and molinate sulfone were shown to be potent inhibitors of this process, suggesting that metabolic activation of molinate is required in vivo. Molinate sulfoxide (>/=10 mg/kg) caused an identical sperm lesion to that of molinate and markedly decreased plasma and testicular testosterone concentration. These effects were not seen with the molinate metabolites 4-hydroxymolinate (10 mg/kg), molinate sulfone (10 mg/kg), and hexamethyleneimine (10 mg/kg). Since the sperm lesion is a secondary event caused by a disruption of spermatogenesis, this would imply that the testis lesion and the reproductive impairment are also a consequence of molinate sulfur oxidation.

Formic acid excretion in rats exposed to trichloroethylene: a possible explanation for renal toxicity in long-term studies.

Rats exposed to trichloroethylene, either by gavage or by inhalation, excreted large amounts of formic acid in urine which was accompanied by a change in urinary pH, increased excretion of ammonia, and slight increases in the excretion of calcium. Following a single 6-h exposure to 500 ppm trichloroethylene, the excretion of formic acid was comparable to that seen after a 500 mg/kg dose of formic acid itself, yet the half-life was markedly different. Formate excretion in trichloroethylene treated rats reached a maximum on day 2 and had a half-life of 4-5 days, whereas urinary excretion was complete within 24 h following a single dose of formic acid itself. Formic acid was shown not to be a metabolite of trichloroethylene. When rats were exposed to 250 or 500 ppm trichloroethylene, 6 h/day, for 28 days, the only significant effects were increased formic acid and ammonia excretion, and a change in urinary pH. There was no evidence of morphological liver or kidney damage. Long-term exposure to formic acid is known to cause kidney damage suggesting that excretion of this acid may contribute to the kidney damage seen in the long-term studies with trichloroethylene.

Molinate: rodent reproductive toxicity and its relevance to humans--a review.

Molinate is a thiocarbamate herbicide used on rice. During the evaluation of the compound for regulatory compliance, an adverse effect on male reproduction in rats was observed. This led to extensive investigations in rats, mice, rabbits, dogs, monkeys, and humans, resulting in a description of the cause of the effect and establishing an empirical case for rodent specificity. More recent investigations have also shown an effect on the ovaries in rodents. A series of investigations into the mechanism of action to support the view that the effect was specific to rodents has been concluded. The results from this investigation are drawn together and show that the mode of action is via a metabolite, the sulfoxide, which is primarily found in rodents, and that the lesion in both rodent sexes is elicited via inhibition of the enzyme neutral cholesterol ester hydrolase, resulting in interference with mobilization of cholesterol from high-density lipoprotein, a path specific to rodents. Thus, the mechanism of action is such that the effect cannot be elicited in other species including humans.