Analysis of the progesterone displacement of its human serum albumin binding site by beta-estradiol using biochromatographic approaches: effect of two salt modifiers

The mechanisms of (i) the binding of two sex-hormones (i.e. progesterone and beta-estradiol) to human serum albumin (HSA) and (ii) the progesterone displacement of its HSA binding cavity by beta-estradiol were studied by biochromatography using three different methods. In the first time, zonal elution method was used to prove the direct competition effect between the two sex-hormone. In the second time, the competition effect between beta-estradiol and progesterone to bound on the same HSA site was analysed by the competitive bi-Langmuir approach. Finally, the thermodynamic data of these two binding processes were studied. The Gibbs free energy value (Delta(approximately)G degrees) of the displacement equilibrium was negative demonstrating that beta-estradiol displaced progesterone of its HSA binding cavity. Moreover, the effect of two chloride modifiers (i.e. Na(+), Mg(2+)) on these two binding processes were analysed. Results showed that in the salt biological concentration ranges, the Mg(2+) cation enhanced strongly the bioavailable progesterone, whereas the Na(+) cation interacted slowly on the progesterone displacement of its HSA binding site by beta-estradiol. This study showed that it must be useful to carry out more in vivo test on the magnesium supplementation effect for women who suffer from estrogen dominance syndrome.     

Proteomics application exercise of the Swiss Proteomics Society: report of the SPS'02 session

After the success of the mass spectrometry (MS) round table that was held at the first Swiss Proteomics Society congress (SPS'01) in Geneva, the SPS has organized a proteomics application exercise and allocated a full session at the SPS'02 congress. The main objective was to encourage the exchange of expertise in protein identification, with a focus on the use of mass spectrometry, and to create a bridge between the users' questions and the instrument providers' solutions. Two samples were sent to fifteen interested labs, including academic groups and MS hardware providers. Participants were asked to identify and partially characterize the samples. They consisted of a complex mixture of peptide/proteins (sample A) and an almost pure recombinant peptide carrying post-translational modifications (sample B). Sample A was an extract of snake venom from the species Bothrops jararaca. Sample B was a recombinant and modified peptide derived from the shrimp Penaeus vannamei penaeidin 3a. The eight labs that returned results reported the use of a wide range of MS instrumentation and techniques. They mentioned a variety of time and manpower allocations. The origin of sample A was generally identified together with a number of database protein entries. The difficulty of the sample identification lay in the incomplete knowledge of the Bothrops species genome sequence and is discussed. Sample B was generally and correctly identified as penaeidin. However, only one group reported the full primary structure. Interestingly, the approaches were again varied and are discussed in the text.     

Which future for the French Pyrenean brown bear (Ursus arctos) population? An approach using stage-structured deterministic and stochastic models

The Pyrenean brown bear (Ursus arctos) population is considered as one of the most seriously threatened with extinction in Western Europe. To assess its viability and possible needs of augmentation, we develop deterministic and stochastic stage-structured demographic models. The deterministic model reveals that a bear population cannot have a high annual growth rate and is particularly sensitive to breeder survival. High demographic parameters appear to be crucial to population persistence, especially for a small population that remains vulnerable to demographic and environmental stochasticities. The Pyrenean population cannot therefore be considered as viable. Successful conservation strategies for this population would require releasing more bears in both sub-populations in the near future.     

Determinants of transpyloric fluid transport: a study using combined real-time ultrasound,manometry, and impedance recording

Intraluminal impedance recording has made it possible to record fluid transport across the pylorus during the interdigestive state without filling the stomach. During antral phase II, fluid transport occurs with and without manometrically detectable antral contraction. Our aim was to investigate the relationships between ultrasonographic patterns of antral contraction, manometric pressure waves, and transpyloric fluid transport during antral phase II. Antral wall movements were recorded by real-time ultrasound (US) in eight healthy volunteers (mean age 24 +/- 7 yr) during 17 +/- 5 min of antral phase II. Concomitantly, a catheter positioned across the pylorus, monitored by transmucosal potential difference measurement, recorded five impedance signals (1 antral, 1 pyloric, and 3 duodenal) and six manometric signals (2 antral, 1 pyloric, and 3 duodenal). Antral contractions detected by US at the level of the two antral impedance electrodes were classified according to their association with a pyloric opening or a duodenal contraction. Transpyloric liquid transport events (impedance drop of >40% of the baseline with an antegrade or retrograde propagation) and manometric pressure waves (amplitude and duration) were identified during the whole study and especially during each period of US antral contraction. A total of 110 antral contractions was detected by US. Of these, 79 were also recorded by manometry. Fluid transport across the pylorus was observed in 70.9% of the US-detected antral contractions. Pyloric opening was observed in 98.6% of the contractions associated with fluid transport compared with 50% in the absence of fluid transport (P < 0.05). Antral contractions associated with fluid transport were significantly (P < 0.05) more often propagated to the duodenum (92%) than those without fluid transport (53%). Pressure waves associated with fluid transport were of higher amplitude (208 mmHg, range 22-493) and longer duration (7 s, range 2.5-13.5 s) than those not associated with fluid transport (102 mmHg, range 18-329 mmHg, and 4.1 s, range 2-8.5 s; P < 0.05). The propagation of the antral contractions in the duodenum in US was always associated with a pyloric opening, whereas only 8 of the 25 contractions without duodenal propagation were associated with a pyloric opening (P < 0.05). The presence of duodenal contractile activity before the onset of an antral contraction in US was always accompanied by pyloric opening and with fluid transport in 93.3%, compared with 56.8% in its absence (P < 0.05). In antral phase II, US is the most sensitive technique to detect antral contractions. Transpyloric fluid transport observed in relation to antral contractions occurs mainly in association with contractions of high amplitude and long duration and is associated with pyloric opening and/or duodenal propagation.     

Hemispheric dissociation in access to the human semantic system

Patient studies suggest that speech and environmental sounds are differentially processed by the left and right hemispheres. Here, using functional imaging in normal subjects, we compared semantic processing of spoken words to equivalent processing of environmental sounds, after controlling for low-level perceptual differences. Words enhanced activation in left anterior and posterior superior temporal regions, while environmental sounds enhanced activation in a right posterior superior temporal region. This left/right dissociation was unchanged by different attentional/working memory contexts, but it was specific to tasks requiring semantic analysis. While semantic processing involves widely distributed networks in both hemispheres, our results support the hypothesis of a dual access route specific for verbal and nonverbal material, respectively.