Normalizing dietary exposure across age by scaling to body size

RIVM/SIR PORS no. 12063It is usually assumed that the higher dietary exposure to substances (in mg/kg bw) in young individuals compared to adults is the resultant of a relatively high consumption needed for growth. When this relatively high exposure of young individuals temporarily exceeds the human limit value, the assessment of possible health risks is not straightforward. The aim of this study was to find a way of scaling exposure in order to reduce the effect of age on the dietary intake. Several (allometric) scaling approaches were applied to explore their impact on age-related intake patterns. It was demonstrated that allometric scaling reduces the effect of body weight. Nevertheless, the results indicate that the higher exposure in young individuals is not only the resultant of a relatively high consumption needed for growth, but still contains influences of body weight. Therefore the conclusion was drawn that a different scaling of dietary exposure is not expedient. It is advised that, when a human limit value is exceeded for a relatively short period, the characteristics (e.g. accumulating properties) of the compound and the design of the toxicological studies informing the human limit value are examined closely to assess the health risk.VW

Serum levels of matrix metalloproteinases-2 and-9 and their tissue inhibitors in inflammatory neuromuscular disorders

We monitored serum levels of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) before and during intravenously applied immunoglobulin (IVIG) therapy in 33 patients with chronic immune-mediated neuropathies and myopathies and 15 controls. Baseline MMP-2 and TIMP-2 serum levels were lower and MMP-9 and TIMP-1 serum levels higher in all patients compared to age-matched controls. Eight days after IVIG treatment, MMP-2, TIMP-2, and TIMP-1 serum levels increased, while MMP-9 serum levels decreased, indicating tissue repair. After 60 days, MMP-9 levels increased, MMP-2 approached normal levels, while TIMP-1 and TIMP-2 serum levels were below day 8 levels, indicating relapsing tissue damage. Comparing the MMP/TIMP results with the clinical courses, IVIG treatment tended to change MMP/TIMP levels in a way that paralleled clinical improvement and relapse. In sum, during a distinct time period, IVIG therapy seems to be able to modulate VIMP-mediated tissue repair. Copyright (c) 2006 S. Karger AG, Basel

Impacts des effluents liquides industriels sur l’environnement urbain d’Abidjan - Côte D’Ivoire

Au cours de ces dernières années, les pouvoirs publics ivoiriens ont fait de l’industrialisation l’un des maillons essentiels du développement, après le succès de l’agriculture. Mais la mise en oeuvre de cette politique pose parfois des problèmes d’environnement à Abidjan. La présente étude a pour objectif principal d’évaluer à travers six paramètres (T °C, pH, DCO, DBO5, MES et MGT), les impacts environnementaux négatifs des effluents industriels dans le milieu urbain d’Abidjan. Pour ce faire, des analyses physico-chimiques de 36 échantillons de rejets industriels, ont été réalisées. A l’exception du pH et de la température, les valeurs extrêmes des paramètres de pollution (DCO, DBO5, MES et MGT respectivement de 1392,83 mg O2/l, 910,03 mg O2/l, 231,53 mg/l et 332,67 mg/l) sont largement supérieures à la norme ivoirienne. Ce qui indique que la zone urbaine d’Abidjan est polluée. Par ailleurs, l’activité industrielle a favorisé aux alentours des zones industrielles d’Abidjan (Yopougon et Port-Bouët), des habitats précaires avec leurs corolaires de maladies (paludisme (68,4%), fièvre typhoïde (12,2%), etc.) et les mauvaises conditions de vie (53,4%). Au regard de ce qui précède, il serait recommandable aux industriels de mettre l’accent sur l’abattement des paramètres en deçà des normes. Les structures de contrôle étatique devraient assurer leur rôle régalien au sein des zones industrielles. © 2013 International Formulae Group. All rights reserved.Mots clés: Entreprises industrielles, Abidjan, paramètres physico-chimiques, Environnement, Impacts, pollution

Variation diurne de la composition chimique et influence sur les propriétés antimicrobiennes de l’huile essentielle de Ocimum canum Sims cultivé au Bénin

L’huile essentielle de Ocimum canum Sims (Lamiaceae) obtenue par hydrodiffusion à différents moments de la journée a été analysée par GC/FID et GC/SM puis testée sur différentes bactéries par la microtechnique de dilution. Le rendement et la composition chimique de l’huile varient selon le temps et l’ensoleillement. Abondant le matin à 7 heures (1,71±0,01%), le rendement décroît progressivement avec l’augmentation des rayons solaires, jusqu’à son minimum à 13 heures (1,35±0,01%) quand le soleil est au zénith, avant de croître à nouveau à sa valeur la plus élevée (1,78±0,02% à 19 h) au couché du soleil. Plus de 54 composés représentant près de 98% des hydrodiffusats, ont été identifiés dans les différents échantillons. Les principaux sont : α-thujène (5,56 à 7,85%), β-myrcene (2 à 6,94%), δ-3-carène (3,07 à 4,84%), p-cymène (14,61 à 22,8%), g-terpinène (6,05 à 10,7%), carvacrol (7,94 à 30,8%), β-caryophyllène (0,15 à 18,86%) et β- sélinène (2,74 à 14,41%). Les taux de certains constituants comme β-caryophyllène et β-sélinène croissent avec l’ensoleillement contrairement à ceux du carvacrol, p-cymène. Cette variation diurne perturbe la synergie d’action des constituants de l’huile qui présentent une forte activité inhibitrice (0,38 à 7,19 mg/ml) sur Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25923, Acinetobacter baumannii ATCC 19609 et Staphylococcus aureus résistante 1199B NorA. Les huiles obtenues à 7 heures et 19 heures sont les plus efficaces à faible concentration (0,38 à 2,88 mg/ml). Pour la première fois, l'interaction est démontrée entre variation diurne de la composition chimique et propriétés antimicrobiennes de l'huile essentielle de Ocimum canum Sims du Bénin.Keywords: Ocimum americanum, composés volatils, Chémotype à carvacrol Variation diurne-Activité antibactérienn

Dispelling urban myths about default uncertainty factors in chemical risk assessment - Sufficient protection against mixture effects?

© 2013 Martin et al.; licensee BioMed Central LtdThis article has been made available through the Brunel Open Access Publishing Fund.Assessing the detrimental health effects of chemicals requires the extrapolation of experimental data in animals to human populations. This is achieved by applying a default uncertainty factor of 100 to doses not found to be associated with observable effects in laboratory animals. It is commonly assumed that the toxicokinetic and toxicodynamic sub-components of this default uncertainty factor represent worst-case scenarios and that the multiplication of those components yields conservative estimates of safe levels for humans. It is sometimes claimed that this conservatism also offers adequate protection from mixture effects. By analysing the evolution of uncertainty factors from a historical perspective, we expose that the default factor and its sub-components are intended to represent adequate rather than worst-case scenarios. The intention of using assessment factors for mixture effects was abandoned thirty years ago. It is also often ignored that the conservatism (or otherwise) of uncertainty factors can only be considered in relation to a defined level of protection. A protection equivalent to an effect magnitude of 0.001-0.0001% over background incidence is generally considered acceptable. However, it is impossible to say whether this level of protection is in fact realised with the tolerable doses that are derived by employing uncertainty factors. Accordingly, it is difficult to assess whether uncertainty factors overestimate or underestimate the sensitivity differences in human populations. It is also often not appreciated that the outcome of probabilistic approaches to the multiplication of sub-factors is dependent on the choice of probability distributions. Therefore, the idea that default uncertainty factors are overly conservative worst-case scenarios which can account both for the lack of statistical power in animal experiments and protect against potential mixture effects is ill-founded. We contend that precautionary regulation should provide an incentive to generate better data and recommend adopting a pragmatic, but scientifically better founded approach to mixture risk assessment. © 2013 Martin et al.; licensee BioMed Central Ltd.Oak Foundatio

Population ecology of the sea lamprey (Petromyzon marinus) as an invasive species in the Laurentian Great Lakes and an imperiled species in Europe

The sea lamprey Petromyzon marinus (Linnaeus) is both an invasive non-native species in the Laurentian Great Lakes of North America and an imperiled species in much of its native range in North America and Europe. To compare and contrast how understanding of population ecology is useful for control programs in the Great Lakes and restoration programs in Europe, we review current understanding of the population ecology of the sea lamprey in its native and introduced range. Some attributes of sea lamprey population ecology are particularly useful for both control programs in the Great Lakes and restoration programs in the native range. First, traps within fish ladders are beneficial for removing sea lampreys in Great Lakes streams and passing sea lampreys in the native range. Second, attractants and repellants are suitable for luring sea lampreys into traps for control in the Great Lakes and guiding sea lamprey passage for conservation in the native range. Third, assessment methods used for targeting sea lamprey control in the Great Lakes are useful for targeting habitat protection in the native range. Last, assessment methods used to quantify numbers of all life stages of sea lampreys would be appropriate for measuring success of control in the Great Lakes and success of conservation in the native range