A nonlabeled method to evaluate cortisol production rate by modeling plasma CBG-free cortisol disposition

This study aimed to develop a nonlabeled method for the measurement of cortisol production rate to evaluate adrenal function. The cortisol production rate determination requires that of cortisol clearance, which is not a parameter but a variable resulting from the saturable binding of cortisol to corticosteroid-binding globulin (CBG). Our method is based on evaluation of the plasma clearance of the CBG-free cortisol fraction. This parameter was evaluated from a pharmacokinetic model of total plasma cortisol disposition that takes into account specific binding of the corticoid to CBG in the plasma. We have shown that the CBG-free cortisol kinetics and CBG-binding parameters thus evaluated are not statistically different from those obtained by the radioisotopic method and equilibrium dialysis, suggesting that the plasma CBG-free cortisol clearance is independent of the total plasma cortisol concentrations and represents the actual parameter of cortisol elimination. We validated this modeling approach by using it to calculate the in vivo entry rate of cortisol mimicked by the perfusion of cortisol at a known rate.     

Hydrogen-deuterium exchange in membrane proteins monitored by IR spectroscopy: a new tool to resolve protein structure and dynamics

As more and more high-resolution structures of proteins become available, the new challenge is the understanding of these small conformational changes that are responsible for protein activity. Specialized difference Fourier transform infrared (FTIR) techniques allow the recording of side-chain modifications or minute secondary structure changes. Yet, large domain movements remain usually unnoticed. FTIR spectroscopy provides a unique opportunity to record (1)H/(2)H exchange kinetics at the level of the amide proton. This approach is extremely sensitive to tertiary structure changes and yields quantitative data on domain/domain interactions. An experimental setup designed for attenuated total reflection and a specific approach for the analysis of the results is described. The study of one membrane protein, the gastric H(+),K(+)-ATPase, demonstrates the usefulness of (1)H/(2)H exchange kinetics for the understanding of the molecular movement related to the catalytic activity.     

A structural and pharmacological study of alkaloids of Vinca Minor

The three-dimensional structures of five indole alkaloids of Vinca (Vincamine, Vincamone, Apovincamine, Vincaminol, and Desoxyvincaminol) are determined theoretically and compared with the available experimental data. The main frame of all these compounds presents a similar structure: planar for the indole moiety, and pan-shaped centered on the C-3 atom for the second moiety. From this central atom a particularly active hydrogen atom points downwards. The main structural parameters obtained theoretically are compared with biological activities (arterial blood flow in brain). Some possible active centers, however, are proposed.     

Quality assessment of urban trees: a comparative study of physiological characterisation,airborne imaging and on site fluorescence monitoring by the OJIP-test

The purpose of this paper is to demonstrate the complementary utility of chlorophyll fast fluorescence OJIP transient (from 50 microns to 1s) measurements in the aerial study of rows of trees. We identify limitations in photochemical events induced by urban injuries on Platanus acerfolia L. using the JIP-test procedure. The Performance Index (PIABS) showed the largest dynamic range to characterise the vitality of trees. Individual trees were graded into three quality groups based on the individual PIABS value compared to the overall average for trees in the alley. These groups are: high performers, with PIABS 50% higher than the alley average; normal trees, with a deviation from the alley average between -50% and %; and poor performers, whose deviation from the alley average was -50% or less. Trees also were grouped into five vitality categories on the basis of a stereoscopic and morphologic observation of the symmetry of tree crowns, percentage of defoliation and reflectance property in the visible and infra-red range. Here, we report a remarkable correlation between the airborne remote sensing data and the on-site fluorescence measurements.     

A family segregating a Friedreich ataxia phenotype that is not linked to the FRDA locus

Friedreich ataxia is an autosomal recessive neurodegenerative disorder. The genetic homogeneity to the FRDA locus on chromosome 9q13-21.1 has been observed in families from different ancestries. We report a Spanish family with two affected and three unaffected children. The segregated classical Friedreich ataxia did not show the expected linkage. The analysis focusses on flanking markers FR1, FR2, FR7 and FR5, excluding linkage 1 cM around the FRDA locus. The unique clinical hallmark in this family was the absence of cardiomyopathy after a long-term follow-up in the two affected children. In both patients serum vitamin E levels were normal. The present observations support the existence of a second locus in Friedreich ataxia, and we suggest that this form could be clinically characterized by the absence of muscular heart disease.     

Comparison of different media for the enumeration of Aeromonas sp. in freshwaters

I. KERSTERS, N. SMEYERS AND W. VERSTRAETE. 1996. Ampicillin-dextrin agar (ADA), m-Aeromonas agar (mA), starch glutamate ampicillin penicillin C-glucose agar (SGAP-10C), trehalose agar (TRE) and ampicillin bile salts inositol xylose agar (MIX) were evaluated for the isolation of Aeromonas sp. from aquatic environments. Recovery of pure cultures was excellent on all media, except for Aer. sobria on SGAP-10C and MIX agars. Recovery of Aeromonas sp. from freshwaters was comparable on ADA, mA, SGAP-10C and TRE. The most selective media were SGAP-10C and ADA, which yielded an average reduction factor of more than 2.9 log. The ability to differentiate Aeromonas sp. from the background microbiota present in freshwaters was best on ADA. The present findings indicate that ADA is the most adequate medium for the selective isolation of Aeromonas sp. from freshwaters.     

C(4)-h and c(5)-h Tautomers of Amthamine and Histamine Monocations

Tautomers and conformers (T/C's) involving the C4 and C5 atoms of the thiazole or imidazole rings were characterized in amthamine (2-amino-5-(2'-aminoethyl)-4-methylthiazole) and histamine (4(5)-2'-aminoethylimidazole), respectively. Critical points of the potential energy surfaces were calculated at the RHF/6-31G** level, using analytical gradients. Conformers were also determined at the MP2/6-31G**//6-31G** and MP2/6-31G**//MP2/6-31G** levels. In amthamine, a gauche conformer of C(5)-H tautomer, I+, turns out to be the second most stable T/C in the gas phase in the RHF approach. MP2 calculations generally yield larger potential energy. Topology of the charge density shows internal electrostatic interactions between S1 ... N for some of the gauche conformers (I+ and L+). Transition state structures for conformational changes and internal proton transfer reactions have also been characterized. In histamine, the C(4)-H tautomers are more stable than the C(5) -H ones, and they have a much higher potential energy than the most stable tautomers of amthamine. N(1) C(i)-H tautomers present similar electronic features to those of amthamine. Internal hydrogen bonds (HyB) and the ring formed in the gauche structures with internal HyB's have been characterized by using the charge density topology procedures. MP2 results are approximately similar to the RHF results, especially with respect to the conformational angles, the potential energy being larger than that from the RHF wavefunction. MP2 distances of HyB's reveal stronger HyB's than the RHF ones.     

In search of a correlation between the electron affinity and the radiosensitizing activity of some glyoxylic compounds.

The electron affinity of some glyoxylic compounds with radiosensitizing properties was evaluated using different approaches. The half-wave reduction potentials were measured by polarography, and the molecular structures in solution were determined by NMR spectroscopy. The electron affinity of the unhydrated and hydrated molecules was theoretically evaluated by means of a semi-empirical quantum mechanical procedure, the MNDO. The possible correlations between these values and the radiosensitizing efficiency of these glyoxylic compounds is discussed.