Solid-phase microextraction and chiral HPLC analysis of ibuprofen in urine

A simple and rapid solid-phase microextraction method was developed for the enantioselective analysis of ibuprofen in urine. The sampling was made with a polydimethylsiloxane-divinylbenzene coated fiber immersed in the liquid sample. After desorptioning from the fiber, ibuprofen enantiomers were analyzed by HPLC using a Chiralpak AD-RH column and UV detection. The mobile phase was made of methanol-pH 3.0 phosphoric acid solution (75:25, v/v), at a flow rate of 0.45 mL/min. The mean recoveries of SPME were 19.8 and 19.1% for (-)-R-ibuprofen and (+)-(S)-ibuprofen, respectively. The method was linear at the range of 0.25-25 microg/mL. Within-day and between-day assay precision and accuracy were below 15% for both ibuprofen enantiomers at concentrations of 0.75, 7.5 and 20 microg/mL. The method was tested with urine quality control samples and human urine fractions after administration of 200 mg rac-ibuprofen.     

Effects of eicosanoid biosynthesis inhibitors on the prophenoloxidase-activating system and microaggregation reactions in the hemolymph of Rhodnius prolixus infected with Trypanosoma rangeli

Investigations on the effects of eicosanoid biosynthesis inhibitors on the hemocyte microaggregation and prophenoloxidase (proPO)-activating system in the hemolymph, parasitemia and mortality of Rhodnius prolixus infected with Trypanosoma rangeli were performed. Hemocoelic injection of live T. rangeli epimastigotes into fifth-instar larvae of R. prolixus that previously fed on blood containing an inhibitor of phospholipase A(2) (dexamethasone), a specific inhibitor of the cyclooxygenase pathway (indomethacin), and a non-selective lipoxygenase inhibitor (NDGA) (i) reduced the hemocyte microaggregation, (ii) attenuated the proPO system in the hemolymph and (iii) enhanced parasitemia and mortality induced by the parasite challenge in these insects. The effects obtained by dexamethasone administered orally were counteracted by inoculation of the insects with arachidonic acid. We suggest that the infectivity of T. rangeli can be increased by interference with the R. prolixus immune system. This is the first demonstration that the triatomine's immune responses to a parasite infection are modulated by a physiological system that includes eicosanoid biosynthesis.     

A geographically explicit genetic model of worldwide human-settlement history

Currently available genetic and archaeological evidence is generally interpreted as supportive of a recent single origin of modern humans in East Africa. However, this is where the near consensus on human settlement history ends, and considerable uncertainty clouds any more detailed aspect of human colonization history. Here, we present a dynamic genetic model of human settlement history coupled with explicit geographical distances from East Africa, the likely origin of modern humans. We search for the best-supported parameter space by fitting our analytical prediction to genetic data that are based on 52 human populations analyzed at 783 autosomal microsatellite markers. This framework allows us to jointly estimate the key parameters of the expansion of modern humans. Our best estimates suggest an initial expansion of modern humans approximately 56,000 years ago from a small founding population of approximately 1,000 effective individuals. Our model further points to high growth rates in newly colonized habitats. The general fit of the model with the data is excellent. This suggests that coupling analytical genetic models with explicit demography and geography provides a powerful tool for making inferences on human-settlement history.     

Relationship between roving behaviour and the diet and client composition of the cleaner fish Labroides bicolor

Diet analyses and observations of cleaning behaviour of two cleaner fishes revealed that Labroides bicolor fed more on client mucus, but Labroides dimidiatus fed more on ectoparasites, and that L. bicolor interacted with fewer species (36 species) compared with L. dimidiatus (44 species). The client species which contributed most to the dissimilarity between cleaner species were the dusky farmerfish Stegastes nigricans and bicolor chromis Chromis margaritifer damselfishes, which L. dimidiatus interacted with more often than L. bicolor, and the striated Ctenochaetus striatus and brown Acanthurus nigrofuscus surgeonfishes, which L. bicolor interacted with more; L. bicolor interacted with all parrotfishes (Scaridae) more. These results confirm the importance of repeated interactions and partner choice in determining the nature of interactions in mutualisms.     

Structural effect of cationic amphiphiles in diacetylenic photopolymerizable membranes

Liposomes have been an excellent option as drug delivery systems, since they are able of incorporating lipophobic and/or lipophilic drugs, reduce drug side effects, increase drug targeting, and control delivery. Also, in the last years, their use reached the field of gene therapy, as non-viral vectors for DNA delivery. As a strategy to increase system stability, the use of polymerizable phospholipids has been proposed in liposomal formulations. In this work, through differential scanning calorimetry (DSC) and electron spin resonance (ESR) of spin labels incorporated into the bilayers, we structurally characterize liposomes formed by a mixture of the polymerizable lipid diacetylenic phosphatidylcholine 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (DC(8,9)PC) and the zwitterionic lipid 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), in a 1:1 molar ratio. It is shown here that the polymerization efficiency of the mixture (c.a. 60%) is much higher than that of pure DC(8,9)PC bilayers (c.a. 20%). Cationic amphiphiles (CA) were added, in a final molar ratio of 1:1:0.2 (DC(8,9)PC:DMPC:CA), to make the liposomes possible carriers for genetic material, due to their electrostatic interaction with negatively charged DNA. Three amphiphiles were tested, 1,2-dioleoyl-3-trimetylammonium-propane (DOTAP), stearylamine (SA) and trimetyl (2-miristoyloxietyl) ammonium chloride (MCL), and the systems were studied before and after UV irradiation. Interestingly, the presence of the cationic amphiphiles increased liposomes polymerization, MCL displaying the strongest effect. Considering the different structural effects the three cationic amphiphiles cause in DC(8,9)PC bilayers, there seem to be a correlation between the degree of DC(8,9)PC polymerization and the packing of the membrane at the temperature it is irradiated (gel phase). Moreover, at higher temperatures, in the bilayer fluid phase, more polymerized membranes are significantly more rigid. Considering that the structure and stability of liposomes at different temperatures can be crucial for DNA binding and delivery, we expect the study presented here contributes to the production of new carrier systems with potential applications in gene therapy.     

RNase MC2: a new <Emphasis Type="Italic">Momordica charantia</Emphasis> ribonuclease that induces apoptosis in breast cancer cells associated with activation of MAPKs and induction of caspase pathways

Ribonucleases (RNases) are ubiquitously distributed nucleases that cleave RNA into smaller pieces. They are promising drugs for different cancers based on their concrete antitumor activities in vitro and in vivo. Here we report for the first time purification and characterization of a 14-kDa RNase, designated as RNase MC2, in the seeds of bitter gourd (Momordica charantia). RNase MC2 manifested potent RNA-cleavage activity toward baker’s yeast tRNA, tumor cell rRNA, and an absolute specificity for uridine. RNase MC2 demonstrated both cytostatic and cytotoxic activities against MCF-7 breast cancer cells. Treatment of MCF-7 cells with RNase MC2 caused nuclear damage (karyorrhexis, chromatin condensation, and DNA fragmentation), ultimately resulting in early/late apoptosis. Further molecular studies unveiled that RNase MC2 induced differential activation of MAPKs (p38, JNK and ERK) and Akt. On the other hand, RNase MC2 exposure activated caspase-8, caspase-9, caspase-7, increased the production of Bak and cleaved PARP, which in turn contributed to the apoptotic response. In conclusion, RNase MC2 is a potential agent which can be exploited in the worldwide fight against breast cancer.     

Cadmium Uptake by Lettuce (Lactuca sativa L.) as Basis for Derivation of Risk Limits in Soils

The availability and uptake of Cd by lettuce (Lactuca sativa L.) in two common tropical soils (before and after liming) were studied in order to derive human health-based risk soil concentration. Cadmium concentrations ranging from 1 to 12 mg kg^?1 were added to samples from a clayey Oxisol and a sandy-loam Ultisol under glasshouse conditions. After incubation, a soil sample was taken from each pot, the concentration of Cd in the soil was determined, lettuce was grown during 36 d, and the edible parts were harvested and analyzed for Cd. A positive linear correlation was observed between total soil Cd and the Cd concentration in lettuce. The amount of Cd absorbed by lettuce grown in the Ultisol was about twice the amount absorbed in the Oxisol. Liming increased the soil pH and slightly reduced Cd availability and uptake. CaCl₂ extraction was better than DTPA to reflect differences in binding strength of Cd between limed and unlimed soils. Risk Cd concentrations in the Ultisol were lower than in the Oxisol, reflecting the greater degree of uptake from the Ultisol. The derived risk Cd values were dependent on soil type and the exposure scenario.     

Parental fish change their cannibalistic behaviour in response to the cost-to-benefit ratio of parental care

Partial filial cannibalism, the act of cannibalizing some offspring, has been explained as a response to the high energetic cost of care. I tested this hypothesis by manipulating the cost-to-benefit ratio of care in the scissortail sergeant, Abudefduf sexfasciatus, a tropical damselfish with male care. Background egg mortality was lower than the incidence of cannibalism, confirming that males did not just dispose of dead eggs. Investment in the current brood affected future investment, because males forced to skip a brood cycle put more effort into courtship during the following cycle and obtained larger broods than did unmanipulated males. Any factor influencing the cost-to-benefit ratio of parental care should also affect the incidence of cannibalism. I reduced the cost of care by supplementary feeding and reduced the benefit of care by simulating a decrease in paternity certainty through simulated intrusions by non-nesting males. Supplementary feeding significantly reduced partial filial cannibalism by parental males, a result compatible with the hypothesis that eggs are consumed to cover the energetic costs of parental care. Cannibalism decreased regardless of whether males were fed with conspecific eggs or crabmeat. Cannibalism was only reduced but not fully eliminated by supplementary feeding, and residual levels of cannibalism after feeding were similar to the background rate of egg mortality. Simulated intrusions by non-nesting males led to an increase in filial cannibalism and a decrease in parental effort.