Enalapril and losartan restored blood pressure and vascular reactivity in intrauterine undernourished rats

Epidemiological studies suggest that intrauterine undernutrition plays an important role in the development of arterial hypertension and endothelial dysfunction in adulthood. We have evaluated the effect of the Renin Angiotensin System inhibition on the blood pressure and the mesenteric arteriolar reactivity of the intrauterine undernourished rats. Wistar rats were fed either normal or 50% of the normal intake diets, during the whole gestational period. In this study only the male offspring was used. At 16 weeks of age, the rats were used for the study of blood pressure, microvascular reactivity studied in vivo-in situ to Angiotensin II (Ang II), Bradykinin (Bk) and Acetylcholine (Ach) before and after either losartan (10 mg/kg/15 days) or enalapril (15 mg/kg/21 days) treatment. We also evaluated the mesenteric and plasmatic Angiotensin Converting Enzyme (ACE), renal function, lipid plasmatic content, and insulin and glucose metabolism. Intrauterine undernutrition induced hypertension and increased response of mesenteric arterioles to Ang II and decreased vasodilation to Bk and Ach. The treatments with losartan or enalapril normalized the blood pressure levels and significantly improved the arteriolar responses to Bk, Ach and reduced the response to Ang II. No differences have been detected to ACE activity, renal function, lipid content and insulin and glucose metabolism. This study shows for the first time that Renin Angiotensin System inhibitors can normalize the cardiovascular alterations induced by intrauterine undernutrition.     

The comparative kinetic analysis of Acetocell and Lignoboost® lignin pyrolysis: the estimation of the distributed reactivity models

The non-isothermal pyrolysis kinetics of Acetocell (the organosolv) and Lignoboost? (kraft) lignins, in an inert atmosphere, have been studied by thermogravimetric analysis. Using isoconversional analysis, it was concluded that the apparent activation energy for all lignins strongly depends on conversion, showing that the pyrolysis of lignins is not a single chemical process. It was identified that the pyrolysis process of Acetocell and Lignoboost? lignin takes place over three reaction steps, which was confirmed by appearance of the corresponding isokinetic relationships (IKR). It was found that major pyrolysis stage of both lignins is characterized by stilbene pyrolysis reactions, which were subsequently followed by decomposition reactions of products derived from the stilbene pyrolytic process. It was concluded that non-isothermal pyrolysis of Acetocell and Lignoboost? lignins can be best described by n-th (n>1) reaction order kinetics, using the Weibull mixture model (as distributed reactivity model) with alternating shape parameters.     

On the Definition of Internal Dose Metrics

Internal dose metrics, as computed with pharmacokinetic models, are increasingly used as a means for extrapolating animal toxicological data to humans and to extrapolate across routes of administration. These internal dose metrics are thought to provide a more scientific means of comparing toxicological effects across animal species. The use of internal dose metrics is based on the universal assumption that toxic effects are equal across species if and only if the concentration of the toxic moieties in the target tissue is equal across species. Herein it is shown that this assumption is inconsistent with empirical toxicological data. It is shown that measurement of internal dose metrics in chronological time, as is done for AUC (Area under the concentration curve) and rate of metabolite production per kg of target tissue, does not produce equal toxic effects across species. A consequence of this observation is that the application of pharmacokinetics in risk assessments for such important chemicals as trichloroethylene, vinyl chloride, perchloroethylene, and perchlorate may need reassessment.     

Application of bovine microsatellite markers for genetic diversity analysis of Swiss yak (Poephagus grunniens)

In order to assess the applicability of bovine microsatellite markers for population genetic studies in Swiss yak, 131 bovine microsatellite markers were tested on a panel of 10 animals. Efficient amplification was observed for 124 markers (94.6%) with a total of 476 alleles, of which 117 markers (94.3%) were polymorphic. The number of alleles per locus among the polymorphic markers ranged from two to nine. Seven loci (ILSTS005, BMS424B, BMS1825, BMS672, BM1314, ETH123 and BM6017) failed to amplify yak genomic DNA. Two cattle Y-chromosome specific microsatellite markers (INRA126 and BM861) amplified genomic DNA from both male and female yaks. However, two additional markers on cattle Y-chromosome (INRA124 and INRA189) amplified DNA from only males. Of the polymorphic markers, 24 microsatellites proposed by CaDBase for within- and cross-species comparisons and two additional highly polymorphic markers (MHCII and TGLA73) were used to investigate the genetic variability and the population structure of a Swiss yak herd that included 51 additional animals. The polymorphic information content ranged from 0.355 to 0.752, while observed heterozygosity (HO) ranged from 0.348 to 0.823. Furthermore, a set of 13 markers, organized into three multiplex polymerase chain reactions, was evaluated for routine parentage testing. This set provided an exclusion probability in a family of four yaks (both parents and two offspring) of 0.995. These microsatellites serve as useful tools for genetic characterization of the yak, which continues to be an important domestic livestock species.     

A Functional Magnetic Resonance Imaging (fMRI) Study of Cue-Induced Smoking Craving in Virtual Environments

Smokers who are exposed to smoking-related cues show cardiovascular reactivity and smoking craving compared with their responses to neutral cues, and increased cue reactivity predicts decreased likelihood of successful cessation. Several brain imaging studies suggested four candidate brain regions that might differ in gray matter volumes and densities between smokers and nonsmokers. However, in these studies, smokers were only exposed to smoking-related objects. In our pilot study utilizing a virtual reality (VR) technique, virtual environments (VEs) were more immersive and evoked smoking craving more effectively than traditionally used methods. In this study, we sought to test whether smokers could experience cue-induced smoking craving inside the MRI scanner by using the VR system. The smoking cue reactivity scenario was based in part on our preliminary task and consisted of 2D and 3D (or VE) conditions. The group mean of participants had increased activity in the prefrontal cortex (PFC), left anterior cingulate gyrus (ACC), left supplementary motor area, left uncus, right inferior temporal gyrus, right lingual gyrus, and right precuneus in the 2D condition. Areas of differential activation in the 3D condition were as follows: left superior temporal gyrus, right superior frontal gyrus, and left inferior occipital gyrus in the 3D condition. This finding is consistent with those of previous studies of nicotine craving showing PFC and ACC activation. However, in the 3D condition, the PFC including the superior frontal gyrus as well as the superior temporal gyrus, inferior occipital gyrus, and cerebellum were activated. Therefore, in the 3D condition, participants seemed to have more attention, visual balance, and coordinating movement than in the 2D condition.     

Structural basis for preferential binding of non-ortho-substituted polychlorinated biphenyls by the monoclonal antibody S2B1

Polychlorinated biphenyls (PCBs) are a family of 209 isomers (congeners) with a wide range of toxic effects. In structural terms, they are of two types: those with and those without chlorines at the ortho positions (2, 2', 6 and 6'). Only 20 congeners have no ortho chlorines. Three of these are bound by the aryl hydrocarbon receptor and are one to four orders of magnitude more toxic than all others. A monoclonal antibody, S2B1, and its recombinant Fab have high selectivity and nanomolar binding affinities for two of the most toxic non-ortho-chlorinated PCBs, 3,4,3',4'-tetrachlorobiphenyl and 3,4,3',4',5'-pentachlorobiphenyl. To investigate the basis for these properties, we built a three-dimensional structure model of the S2B1 variable fragment (Fv) based on the high-resolution crystallographic structures of antibodies 48G7 and N1G9. Two plausible conformations for the complementarity-determining region (CDR) H3 loop led to two putative PCB-binding pockets with very different shapes (models A and B). Docking studies using molecular mechanics and potentials of mean force (PMF) indicated that model B was most consistent with the selectivity observed for S2B1 in competition ELISAs. The binding site in model B had a deep, narrow pocket between V(L) and V(H), with a slight constriction at the top that opened into a wider pocket between CDRs H1 and H3 on the antibody surface. This binding site resembles those of esterolytic antibodies that bind haptens with phenyl rings. One phenyl ring of the PCB fits into the deep pocket, and the other ring is bound in the shallower one. The bound PCB is surrounded by the side chains of TyrL91, TyrL96 and TrpH98, and it has a pi-cation interaction with ArgL46. The tight fit of the binding pocket around the ortho positions of the bound PCBs indicates that steric hindrance of ortho chlorines in the binding site, rather than induced conformational change of the PCBs, is responsible for the selectivity of S2B1.     

On the functional role of Arg172 in substrate binding and allosteric transition in Escherichia coli glucosamine-6-phosphate deaminase

Glucosamine-6-phosphate deaminase from Escherichia coli (EC 3.5.99.6) is an allosteric enzyme, activated by N-acetylglucosamine 6-phosphate, which converts glucosamine-6-phosphate into fructose 6-phosphate and ammonia. X-ray crystallographic structural models have showed that Arg172 and Lys208, together with the segment 41-44 of the main chain backbone, are involved in binding the substrate phospho group when the enzyme is in the R activated state. A set of mutants of the enzyme involving the targeted residues were constructed to analyze the role of Arg172 and Lys208 in deaminase allosteric function. The mutant enzymes were characterized by kinetic, chemical, and spectrometric methods, revealing conspicuous changes in their allosteric properties. The study of these mutants indicated that Arg172 which is located in the highly flexible motif 158-187 forming the active site lid has a specific role in binding the substrate to the enzyme in the T state. The possible role of this interaction in the conformational coupling of the active and the allosteric sites is discussed.     

Protease-activated receptor 2 in regulation of bronchomotor tone: effect of tobacco smoking

Protease-activated receptors are G protein-coupled receptors activated by serine-proteases. Protease-activated receptor 2 is involved in the regulation of airway smooth muscle tone but its effects vary according to species and experimental conditions. We determined the effects of protease-activated receptor 2 activation on smooth muscle tone and airway reactivity to histamine in guinea pigs and smoking or non-smoking humans. The effects of trypsin and protease-activated receptor activating peptide on the isometric tension and response to histamine of guinea pig tracheal and human bronchial rings were studied. Human tissues were obtained from 6 smokers and 4 non-smokers. We assessed the effects of epithelial removal, inhibitors of cyclooxygenases, nitric oxide synthases, neutral endopeptidase and antagonists of acetylcholine, histamine, bradykinin and tachykinin receptors. Bronchomotor responses to protease-activated receptor 2 activation were variable in guinea pig, in half of animals PAR2 activation induced smooth muscle relaxation through the epithelial release of prostanoids but not of nitric oxide. In human airways, protease-activated receptor 2 activation reduced responsiveness to histamine in bronchial rings from smokers but increased responsiveness in bronchi from non-smokers. This study demonstrates an influence of tobacco smoking on the effect of protease-activated receptor 2 activation on airway responsiveness in humans, with an increased protection against histamine-induced contractions, probably through an increased epithelial release of prostanoids. The role of airway protease-activated receptor 2 may be to maintain smooth muscle tone homeostasis.     

Patterns of bushmeat hunting and perceptions of disease risk among central African communities

There is a great need to determine the factors that influence the hunting, butchering and eating of bushmeat to better manage the important social, public health and conservation consequences of these activities. In particular, the hunting and butchering of wild animals can lead to the transmission of diseases that have potentially serious consequences for exposed people and their communities. Comprehension of these risks may lead to decreased levels of these activities. To investigate these issues, 3971 questionnaires were completed to examine the determinants of the hunting, butchering and eating of wild animals and perceptions of disease risk in 17 rural central African villages. A high proportion of individuals reported perceiving a risk of disease infection with bushmeat contact. Individuals who perceived risk were significantly less likely to butcher wild animals than those who perceived no risk. However, perception of risk was not associated with hunting and eating bushmeat (activities that, compared with butchering, involve less contact with raw blood and body fluids). This suggests that some individuals may act on perceived risk to avoid higher risk activity. These findings reinforce the notion that conservation programs in rural villages in central Africa should include health-risk education. This has the potential to reduce the levels of use of wild animals, particularly of certain endangered species (e.g. many non-human primates) that pose a particular risk to human health. However, as the use of wild game is likely to continue, people should be encouraged to undertake hunting and butchering more safely for their own and their community's health.