Does Manganese Protect Cultured Human Skin Fibroblasts Against Oxidative Injury by Uva, Dithranol and Hydrogen Peroxide?

Reactive oxygen species (ROS) are involved in the mechanism of photoaging and carcinogenesis. Skin is endowed with antioxidant enzymes including superoxide dismutases (SOD): cytosolic copper zinc SOD and mitochondrial manganese SOD. The aim of our study was to estimate the protective effect of manganese against oxidative injury on cultured human skin fibroblasts. Dithranol, hydrogen peroxide and UV-A radiation (375 nm) were employed as oxidative stressors. The supply of manganese chloride produced an increase in cellular content of this element up to 24 fold without concomitant elevation of MnSOD activity. Nevertheless, manganese protects cells against two of the three ROS generating systems assessed, namely hydrogen peroxyde and UV-A. This protective effect depends on the concentration of manganese in the medium, 0.1 mM and 0.2 mM protect against UVA cytotoxicity, only 0.2 mM protects against H₂O₂ cytotoxicity.     

Parenteral supplementation with zinc in surgical patients corrects postoperative serum-zinc drop

Zinc has been known for a long time to facilitate wound healing. But, so far, supplementation trials in patients treated by major severity surgery gave either partial or controversial results. In a double-blind, randomized study including 30 patients, we show that zinc supplements (30 mg/d for 3 d) administered by a drip correct postoperative drop of serum zinc, that this correction concerns the available part of serum zinc (i.e., zinc that is bound to compounds other than alpha-2 macroglobulin in serum), and that this supplementation can improve clinical wound healing. Possible influence of increased urinary output after the intervention is discussed, and we found that serum cortisol remains stable when zinc/albumin ratio is stable, and increases sharply when the same ratio drops. Cortisol, therefore, seems to play a major role in zinc redistribution after surgery.     

Prokaryotic aminopeptidase activity along a continuous salinity gradient in a hypersaline coastal lagoon (the Coorong, South Australia)

The relation between climatic parameters (relative air humidity) and the water activity of the Urmia Sea water determines the possible maximum evaporation of the lake. Using the Pitzer thermodynamic approach, the activity of the Urmia Lake water during evaporation was calculated and compared to the present relative air humidity above the water. Present climatic conditions allow the Urmia Sea water to evaporate down to water with activity of 0.55, corresponding to the lowest air humidity measured over the lake. This water activity falls in the range of halite precipitation, while carnalite precipitation starts at somewhat lower (a H₂O = 0.499) point. Our dynamic model predicts that for air humidity as low as 55% (reflecting present climate conditions), the Urmia Sea level may drop to as low as 1270 m (i. e., 1270 m above mean sea level). At that point, the lake water volume will have a volume of 11 km³. For the sake of comparison, at the beginning of 1990, the level of the lake was 1275 m, its volume was 25 km³, and its surface area was 5145 km².     

Can eggs in a cavity be a female secondary sexual signal? Male nest visits and modelling of egg visual discrimination in blue tits

Eggshell colouration is thought to function as a female-specific secondary sexual trait. While tests of this idea are rapidly accumulating in cavity-nesting birds, some fundamental underlying assumptions remain rarely investigated: namely, can males see eggshell coloration and perceive colour differences between the eggs of different females? We tested these two key assumptions in a natural population of blue tits (Cyanistes caeruleus). Using transponders, we tracked male nest visits and found that all males visited their nest-boxes while eggs were present and often visually accessible. Interestingly, some males also visited neighbouring nests. We then tested whether birds could detect eggshell coloration using models of avian colour vision; models were performed with and without limitations on visual performance owing to dim light. Both models found that differences in eggshell brightness were often easier to discriminate than differences in colour; there was more contrast in white eggshell background between clutches than within and its contrast against nest background was repeatable within clutches, suggesting these features could act as signals. Yet, the detectability of these contrasts depended entirely on model assumptions of visual limitations. Consequently, we need a better understanding of underlying visual mechanisms in dim-light environments and behavioural discrimination experiments before confirming the signalling potential of eggshell coloration.     

Relationship between expression of matrix metalloproteinases and migration of epidermal and in vitro generated Langerhans cells

Langerhans cells (LC) are dendritic cells that capture foreign antigens and migrate with them to the regional lymph nodes where they are presented to naive T cells. The possible role of matrix metalloproteinase-9 (MMP-9) in migration was suggested following experiments in a mouse model and in human skin explants. Using in vitro generated LC (iLC) derived from CD34+ cord blood cells and epidermal LC (eLC), we investigated the correlation between MMP-9 and other MMPs production and cell migration. Cells were activated by Bandrowski's base (BB), a chemical allergen, or by recombinant birch pollen allergen 1 (rBetv 1). Contact with allergens triggered migration of these cells, with a maximum rate being reached after 24 h. Migration was preceded by production of MMP-2 and MMP-9; part of the molecules were recovered as pro-MMPs in cell culture supernatant and part were associated with cell membrane proteins. At the cellular level, membrane-type 1 (MT1) and MT3-MMP were also identified. Addition of tumor necrosis factor-alpha (TNF-alpha) initiated pro-MMP-2 and pro-MMP-9 production followed by cell migration in a dose-dependent manner. These data imply that TNF-alpha is a key molecule for MMP production and cell migration. Furthermore, activation of iLC with BB or rBet v 1 induced synthesis of TNF-a and expression of TNF RII on the cell membrane, suggesting an autocrine loop. In conclusion, membrane-associated MMP-2 and-9 rather than soluble MMPs appear to be involved in cell migration.     

Trace-Level Determination of Oxolinic Acid and Flumequine in Soil,River Bed Sediment,and River Water Using Microwave-Assisted Extraction and High-Performance Liquid Chromatography with Fluorimetric Detection

This work presents the optimization of analytical procedures for the determination of two antibiotics, oxolinic acid (OA) and flumequine (FL), in bed sediment, river water, and soil samples. Three extraction methods (microwave-assisted extraction (MAE), ultrasonication, and reflux) were tested, and the highest recoveries were obtained with MAE (94 ± 3% and 95 ± 3% for OA and FL, respectively). A solid-phase extraction (SPE) clean-up step was optimized by comparing two polymeric sorbents: Oasis HLB and Oasis MAX. The final extracts were analyzed by liquid chromatography with fluorimetric detection. Limits of detection (LOD) obtained for OA and FL in soil and sediment ranged from 0.3 to 0.5 µg kg^?1. Meanwhile, a novel SPE procedure was also implemented for OA and FL determination in river water samples. It also relied on the use of Oasis MAX, and recovery rates were in the range 90–94%; LODs were 2 ng L^?1 for both OA and FL. These methods were applied for the analysis of samples taken in the Seine River basin (France). The obtained results demonstrated the widespread occurrence of OA and FL, at ng L^?1 and µg kg^?1 levels in water and sediment/soil, respectively, and their persistence in the environment.     

Increased lipid peroxidation in pregnant women after iron and vitamin C supplementation

Iron overload could promote the generation of free radicals and result in deleterious cellular damages. A physiological increase of oxidative stress has been observed in pregnancy. A routine iron supplement, especially a combined iron and vitamin C supplementation, without biological justifications (low hemoglobin [Hb] and iron stores) could therefore aggravate this oxidative risk. We investigated the effect of a daily combined iron supplementation (100 mg/d as fumarate) and vitamin C (500 mg/d as ascorbate) for the third trimester of pregnancy on lipid peroxidation (plasma TBARS), antioxidant micronutriments (Zn, Se, retinol, vitaminE, (β-carotene) and antioxidant metalloenzymes (RBC Cu-Zn SOD and Se-GPX). The iron-supplemented group (n=27) was compared to a control group (n=27), age and number of pregnancies matched. At delivery, all the women exhibited normal Hb and ferritin values. In the supplemented group, plasma iron level was higher than in the control group (26.90±5.52 mmol/L) and TBARs plasma levels were significantly enhanced (p<0.05) (3.62±0.36 vs 3.01±0.37 mmol/L). No significant changes were observed in plasma trace elements and red blood cell antioxidant metalloenzymes. Furthermore, the α-tocopherol plasma level was lowered in the iron-supplemented groups, suggesting an increased utilization of vitamin E. These data show that pharmalogical doses of iron, associated with high vitamin C intakes, can result in uncontrolled lipid peroxidation. This is predictive of adverse effects for the mother and the fetus. This study illustrates the potential harmful effects of iron supplementation when prescribed only on the assumption of anemia and not on the bases of biological criteria.     

Effect of taurine,l-glutamine and l-histidine addition in an amino acid glucose solution on the cellular bioavailability of zinc

Radioactive zinc was used to study the effect of a binary parenteral nutrient solution, composed of amino acids and glucose, on zinc uptake by fibroblasts. The influence of addition of taurine, l-glutamine and of the increase in l-histidine content of the admixture was assessed. The pure mixture was highly toxic for cells and so it was diluted 1/5 in tyrode buffer with 2% albumin. As compared with cells incubated in the buffer containing albumin, zinc absorption was significantly higher (P < 0.05) in the presence of the amino acids of the mixture. Amino acids thus increased bioavailability by displacing zinc bound to albumin. When the histidine concentration in the nutrient medium (4.2 mm) was doubled, inhibition was noted after 30 min of incubation and zinc uptake thereafter remained comparable to that in histidine-free medium. The addition of glutamine (4.2 mm), usually not present in binary mixtures, resulted in significant differences as compared with glutamine-free control medium. Taurine (0.8 mm), led to a constant increase in zinc uptake by fibroblasts as compared with that obtained with taurine-free mixture. However, ultrafiltration showed that taurine was not able to displace zinc from albumin.