Acute toxicity effects of ibuprofen on behaviour and haematological parameters of African catfish Clarias gariepinus (Burchell, 1822)

Indiscriminate discharge of pharmaceutical waste into the aquatic ecosystem may pose serious health challenges to aquatic biota. The effect of acute exposure to ibuprofen was evaluated using changes in behaviour and haematological parameters under static bio-assay method in Clarias gariepinus. Test specimens were exposed to acute concentrations of ibuprofen (0.28, 0.33, 0.38, 0.43 and 0.48 mg l^?1) for 24, 48, 72 and 96 h durations respectively. Behavioural and phenotypic changes were observed in surviving fish. There were significant (p < 0.05) concentration and duration-dependent increases in erythrocyte (RBC), haemoglobin (Hb), pack cell volume (PCV) and leukocytes (WBC) in treated fish compared to the control. Insignificant decreases (p > 0.05) in mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) were observed in treated fish compared to the control. Ibuprofen elicited dose and duration- dependent decrease in neutrophil counts with the decreases being significant (p < 0.05) in the higher doses of 0.43 and 0.48 mg l^?1. Ibuprofen did not elicit any significant changes in monocytes, basophils and eosinophils. Changes observed in this study showed that ibuprofen negatively affected the health of the fish and we recommend that discharge of ibuprofen into the aquatic environment should be monitored and controlled.     

Age-Associated Impairments in Mitochondrial ADP Sensitivity Contribute to Redox Stress in Senescent Human Skeletal Muscle

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Why Do We Expect Carotenoids to be Antioxidants in vivo?

The antioxidant properties of β-carotene, in addition to its proposed immunomodulatory effects, have often been cited as the factors underlying its role in preventing disease initiation and propagation, yet the strongest evidence for diet and cancer prevention is based on fruit and vegetable intake and not β-carotene or other dietary carotenoids, per se. In the light of the outcome of the ATBC trial, the Physicians Health Study and the premature termination of the CARET study, this review addresses the issue of the antioxidant properties of the carotenoids and poses the questions: do dietary carotenes and xanthophylls have a clear role in disease prevention and are their antioxidant properties relevant to this role? What. do we know about their mechanisms of action in vitro as free radical scavengers?     

Impacts of Mercury on Freshwater Fish-Eating Wildlife and Humans

This paper reviews the current state of knowledge of the toxic effects of mercury on fish-eating birds, mammals, and humans associated with freshwater ecosystems, including new information on the relative risk of elevated methyl Hg exposure for fish-eating birds inhabiting aquatic ecosystems impacted by mining/smelting activities and areas characterized by high geological sources of Hg. The influence of various environmental conditions such as lake pH, DOC, and chemical speciation of Hg, on fish-Hg concentrations and Hg exposure in fish-eating wildlife, are discussed. Although a continuing global effort to decrease the release of this nonessential metal into the environment is warranted, Hg methylation and biomagnification may be limited in some environments due to chemical speciation of mercury in soils and sediments (e.g., HgS) and water quality conditions (e.g., high alkalinity and pH) that do not facilitate high methylation rates. We have shown such limitations for a lake where historic Hg mining greatly increased sediment-Hg loadings, yet Hg increases in small fish of various species are currently lower than expected, and top predators (bald eagles), despite having elevated concentrations of Hg in their blood compared with individuals from nearby lakes, exhibit no Hg-related reproductive impairment or other signs of MeHg intoxication. Recent epidemiological studies have shown that fish-eating human populations may be exposed to Hg sufficient to cause significant developmental effects. However, for humans, we conclude that the current USEPA reference dose for MeHg may be too restrictive, particularly for the less sensitive adult. The health status of indigenous peoples relying on the subsistence harvest of wild foods may be negatively affected by such restrictions.     

Electron exchange coupling in a naturally occurring tetramangano cluster in the mineral helvite, (Mn4S)(SiBeO4)3

The mineral helvite, (Mn₄S)(BeSiO₄)₃, contains discrete tetrahedral Mn₄S⁺⁶ clusters in which the S^?2 is tetrahedrally coordinated and each Mn(II) is in a distorted tetrahedron of one S^?2 and three oxygens; the cluster is situated within an encompassing lattice of SiO₄^?4 and BeO₄^?6 tetrahedra. Mn₄S⁺⁶ centers provide an interesting model for comparison to the polynuclear manganese center that is associated with photosynthetic water oxidation. Magnetic susceptibility data between 77 and 298 K have been measured for a natural helvite sample containing principally Mn₄S⁺⁶ centers but with significant contamination from Mn₃FeS⁺⁶ and Mn₃CaS⁺⁶. The data exhibited Curie-Weiss behavior with μ_eff = 5.969 B.M. and θ = 178.3 K. An analysis of the magnetic susceptibility, based on Van Vleck's formalism, demonstrated the presence of antiferromagnetic coupling, with a coupling constant J = ?5.83 cm^?1. Mössbauer spectra of Mn₃FeS centers in helvite and of Fe₄S centers in the related mineral danalite have also been recorded. Isomer shifts show little temperature dependence and lie in the range 1.23–1.43 $\text{mm}\text{sec.}$. This range is typical of tetrahedrally coordinated Fe(II) in several ionic crystals but is significantly above that of Fe(II) in ferredoxins and below that in the [quinone-Fe(II)-quinone] complex of the photosynthetic bacterium,Rhodopseudomonas sphaeroides. Quadrupole splittings are highly temperature dependent, ranging from 2.4 $\text{mm}\text{sec}$ at 4.2 K to less than 0.5 $\text{mm}\text{sec}$ at 248 K.     

The composition of suberin from the corks of Quercus suber L. and Betula pendula roth

The suberin constituents of Quercus suber and Betula pendula have been isolated after alkaline hydrolysis of the corks and over 80% by weight identified using thin-layer chromatography, preparative thin-layer chromatography, gas-liquid chromatography and combined gas chromatography — mass spectrometry. Long-chain aliphatic acids ranging from C₁₆–C₂₆ comprise about 90% of both suberin fractions; monobasic, α,ω-dibasic, ω-hydroxymonobasic, dihydroxymonobasic, dihydroxydibasic and trihydroxymonobasic acid classes are present. The principal suberin acids of Q. suber are 18-hydroxyoctadecenoic (12%), 22-hydroxydocosanoic (25%), 9,10-dihydroxyoctadecane-1,18-dioic (15%) and 9,10,18-trihydroxyoctadecanoic (8%), and those of B. pendula 9,10,18-trihydroxyoctadecanoic (43%) and 22-hydroxydocosanoic (16%).     

Intracuticular lipids of spinach leaves

The cuticular wax and cutin components of the cuticular membranes isolated from the leaves of two spinach cultivars have been determined. The membranes contain about 0·007 mg/cm² of cuticular wax which comprises monobasic acids (C₁₆–C₃₈) with hexadecanoic as the major component. The amounts of cutin are comparable with those of cuticular wax and the monomeric constituents are predominantly C₁₈ epoxy compounds. The most abundant monomer is 9,10-epoxy-18-hydroxyoctadecanoic acid (up to 63%) together with substantial amounts of 9,10,18-trihydroxyoctadecanoic acid (up to 22%). Also present are 9,10-epoxyoctadecane-1,18-dioic acid (6–7%) dihydroxyhexadecanoic acid (3–4%) and ω-hydroxymonobasic and fatty acid fractions. The tentative identification of two minor components, 18-hydroxyoxooctadecanoic and 9,10-epoxy-12,18-dihydroxyoctadecanoic acids, is also made. Although spinach membranes have a delicate structure their cutin composition is essentially similar to that of much more substantial membranes.