Management accounting and reporting system for International Development Research Centre

Report on the development of an effective management information system for the IDRC - discusses institutional framework of IDRC, administrative aspects of research projects, financing, the accounting and reporting system of the IDRC, the application of the computer-based ISIS system

Contaminant-induced immunotoxicity in harbour seals: Wildlife at risk?

Persistent, lipophilic polyhalogenated aromatic hydrocarbons (PHAHs) accumulate readily in the aquatic food chain and are found in high concentrations in seals and other marine mammals. Recent mass mortalities among several marine mammal populations have been attributed to infection by morbilliviruses, but a contributing role for immunotoxic PHAHs, including the polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) was not ruled out. We addressed this issue by carrying out a semi-field study in which captive harbour seals were fed herring from either the relatively uncontaminated Atlantic Ocean or the contaminated Baltic Sea for 2 years. We present here an overview of results obtained during this study. An impairment of natural killer (NK) cell activity, in vitro T-lymphocyte function, antigen-specific in vitro lymphocyte proliferative responses, and in vivo delayed-type hypersensitivity and antibody responses to ovalbumin was observed in the seals fed the contaminated Baltic herring. Additional feeding studies in PVG rats using the same herring batches suggested that an effect at the level of the thymus may be responsible for changes in cellular immunity, that virus-specific immune responses may be impaired, and that perinatal exposure to environmental contaminants represents a greater immunotoxic threat than exposure as a juvenile or adult. Together with the pattern of TCDD toxic equivalents of different PHAHs in the herring, these data indicate that present levels of PCBs in the aquatic food chain a

Finiteness and anomalies in (4,0) supersymmetric sigma models

Power-counting arguments based on extended superfields have been used to argue that two-dimensional supersymmetric sigma models with (4,0) supersymmetry are finite. This result is confirmed up to three loop order in pertubation theory by an explicit calculation using (1,0) superfields. In particular, it is shown that the finite counterterms which must be introduced into the theory in order to maintain (4,0) supersymmetry are precisely the terms that are required to establish ultra-violet finiteness.Comment: 19 page

Hormonal circadian rhythms in patients with congenital adrenal hyperplasia: identifying optimal monitoring times and novel disease biomarkers

Objectives: The treatment goal in congenital adrenal hyperplasia (CAH) is to replace glucocorticoids while avoiding androgen excess and iatrogenic Cushing's syndrome. However, there is no consensus on how to monitor disease control. Our main objectives were to evaluate hormonal circadian rhythms and use these profiles to identify optimal monitoring times and novel disease biomarkers in CAH adults on intermediate- and long-acting glucocorticoids. Design: This was an observational, cross-sectional study at the National Institutes of Health Clinical Center in 16 patients with classic CAH. Methods: Twenty-four-hour serum sampling for ACTH, 17-hydroxyprogesterone (17OHP), androstenedione (A4), androsterone, DHEA, testosterone, progesterone and 24-h urinary pdiol and 5β-pdiol was carried out. Bayesian spectral analysis and cosinor analysis were performed to detect circadian rhythmicity. The number of hours to minimal (TminAC) and maximal (TmaxAC) adrenocortical hormone levels after dose administration was calculated. Results: A significant rhythm was confirmed for ACTH (r2, 0.95; P<0.001), 17OHP (r2, 0.70; P=0.003), androstenedione (r2, 0.47; P=0.043), androsterone (r2, 0.80; P<0.001), testosterone (r2, 0.47; P=0.042) and progesterone (r2, 0.64; P=0.006). The mean (S.D.) TminAC and TmaxAC for 17OHP and A4 were: morning prednisone (4.3 (2.3) and 9.7 (3.5) h), evening prednisone (4.5 (2.0) and 10.3 (2.4) h), and daily dexamethasone (9.2 (3.5) and 16.4 (7.2) h). AUC0–24 h progesterone, androsterone and 24-h urine pdiol were significantly related to 17OHP. Conclusion: In CAH patients, adrenal androgens exhibit circadian rhythms influenced by glucocorticoid replacement. Measurement of adrenocortical hormones and interpretation of results should take into account the type of glucocorticoid and time of dose administration. Progesterone and backdoor metabolites may provide alternative disease biomarkers

Haematology and clinical chemistry values for harbour seals (Phoca vitulina) fed environmentally contaminated herring remain within normal ranges

Abstract: Twenty-two young harbour seals (Phoca vitulina) were fed herring from either the relatively unpolluted Atlantic Ocean or the heavily polluted Baltic Sea as part of a 2½-year immunotoxicological study. Blood samples taken at regular intervals were analyzed for routine haematology and clinical chemistry. Minimal differences between the two groups were observed in these parameters over the course of the experiment. Of the 20 clinical chemistry parameters analyzed, slight differences were found in serum levels of urea, creatinine, magnesium, and cholesterol. In haematology profiles, red blood cell counts and haematocrit values were higher in seals fed Baltic herring, but these differences diminished over time. Neutrophil counts were also higher in this group of seals, especially during the second half of the feeding study. Factors affecting haematological and clinical chemistry parameters within feeding groups included gender, age, and season. The data collected demonstrate a relative insensitivity of clinical chemistry parameters to the effects of chronic exposure to environmental contaminants accumulated through the food chain, but suggest the induction of clear alterations in differential white blood cel

Morbillivirus infections of aquatic mammals: newly identified members of the genus.

Several disease outbreaks, which have caused the deaths of many thousands of seals and dolphins during the last decade, have now been attributed to infections with newly identified Morbilliviruses. Outbreaks in the late eighties amongst harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) in northwestern Europe and amongst baikal seals (Phoca sibirica) in Siberia were caused by the newly discovered phocine distemper virus and by a strain of canine distemper virus, respectively. Although closely related these two viruses were not identical. They were more distantly related to the viruses which caused mass mortality amongst striped dolphins (Stenella coeruleoalba) in the Mediterranean sea in the early nineties. This dolphin morbillivirus was shown to be closely related to a virus that was found in harbour porpoises (Phocoena phocoena) which had stranded at the coasts of northwestern Europe in the late eighties: porpoise morbillivirus. The present knowledge of the genetic and antigenic relationships of these apparently new members of the genus Morbillivirus with the established members of the genus is presented. In addition, the origin and epizootiological aspects of these newly discovered viruses are discussed. Finally experimental evidence that environmental pollution may have contributed to the severity and extent of these infections in recent years is presented

Relative immunocompetence of the newborn harbour seal, phoca vitulina

The immune system of many mammalian species is not fully developed at birth, with newborns obtaining temporary immunological protection from maternal antibodies. Little is known of the immune system of the harbour seal, and developmental aspects of its immune system have not been systematically studied. We collected blood and milk samples from nine free-ranging mother-pup pairs throughout the lactation period on Sable Island, Canada, in an effort to characterise developmental aspects of the immune system of this newborn pinniped. Pup lymphocytes responded stronger to the mitogens concanavalin A, phytohaemagglutinin, and pokeweed mitogen tha

Electronic transport and vibrational modes in the smallest molecular bridge: H2 in Pt nanocontacts

We present a state-of-the-art first-principles analysis of electronic transport in a Pt nanocontact in the presence of H2 which has been recently reported by Smit et al. in Nature 419, 906 (2002). Our results indicate that at the last stages of the breaking of the Pt nanocontact two basic forms of bridge involving H can appear. Our claim is, in contrast to Smit et al.'s, that the main conductance histogram peak at G approx 2e^2/h is not due to molecular H2, but to a complex Pt2H2 where the H2 molecule dissociates. A first-principles vibrational analysis that compares favorably with the experimental one also supports our claim .Comment: 5 pages, 3 figure

Suppression of natural killer cell activity in harbour seals (Phoca vitulina) fed Baltic Sea herring

Mass mortalities among marine mammal populations in recent years have raised questions about a possible contributory role of contaminants accumulated through the marine food chain. While viruses were shown to be the primary cause of the outbreaks, an immunotoxic action by organochlorine chemicals in affected animals could not be ruled out. We carried out a 2 1/2 -year immunotoxicological experiment in which two groups of 11 harbour seals each were fed herring from either the relatively contaminated Baltic Sea or the relatively uncontaminated Atlantic Ocean. Seals in the Baltic Sea group accumulated 3-4 times higher levels of Ah-receptor-mediated 2,3,7,8-TCDD Toxic Equivalents in blubber than did their Atlantic counterparts following 2 years on the respective diets. Blood was sampled a total of 17 times during the course of the experiment for immunological evaluation, during which time the natural cytotoxic activity of peripheral blood mononuclear cells isolated from seals fed Baltic Sea herring declined to a level approximately 2