[Effect of demographic population factors and individual biological parameters on the rate of neutral molecular evolution].

The dependence of the rate of neutral molecular evolution on biological parameters and demographic population factors was studied based on actual genetic information as an example and using the individual-oriented model of population dynamics. The first part of the study deals with tracing the neutral evolution occurring in the model concurrently with adaptive speciation. The second part concerns the effect of individual biological parameters and demographic population factors of members of the order Testudines (turtles) on the relative evolution rate of the mitochondrial CytB gene. Demographic population factors and individual biological parameters are shown to affect the rate of molecular evolution.

Cyclic dipeptide oxidase from Streptomyces noursei. Isolation, purification and partial characterization of a novel, amino acyl alpha,beta-dehydrogenase.

Cyclic dipeptide oxidase is a novel enzyme that specifically catalyzes the formation of alpha,beta-dehydro-Phe (Delta Phe) and alpha,beta-dehydro-Leu (Delta Leu) residues during the biosynthesis of albonoursin, cyclo(Delta Phe-Delta Leu), an antibiotic produced by Streptomyces noursei. It was purified 600-fold with a 30% overall recovery, and consists of the association of a single type of subunit with a relative molecular mass of 21,066 resulting in a large homopolymer of relative molecular mass over 2,000,000. The enzyme exhibits a typical flavoprotein spectrum with maxima at 343.5 and 447.5 nm, the flavin prosthetic group being covalently bound to the protein. The catalytic reaction of the natural substrate cyclo(L-Phe-L-Leu) occurs in a two-step sequential reaction leading first to cyclo(alpha,beta-dehydro-Phe-L-Leu) and finally to albonoursin. Kinetic parameters for the first step were determined (K(m) = 53 microM; k = 0.69 s(-1)). The enzyme was shown to catalyze the conversion of a variety of cyclo(dipeptides) and can be reoxidized at the expense of molecular oxygen by producing H(2)O(2). This reaction mechanism, which differs from those already described for the formation of alpha,beta-dehydro-amino acids, might consist of the transient formation of an intermediate imine followed by its rearrangement into an alpha,beta-dehydro-residue.

Changes in the physiological and agricultural characteristics of peat-based Bradyrhizobium japonicum inoculants after long-term storage.

Commercial soybean inoculants processed with sterilised peat and stored at 20 degrees C for 1-8 years were used as experimental materials to assess the changes in the physiological activity of Bradyrhizobium japonicum after storage. Viable counts decreased and physiological characteristics of the bacterium changed during storage, with an increase in the time taken for colony appearance on a medium without yeast extract, an increase in the lag time for nodule appearance on soybean grown in glass tubes and a decrease in survival on seeds. All the inoculants produced a significant increase in grain yield in a field experiment. The percentage of efficient cells in the field (relative to the plate counts) decreased as the length of storage increased. These results suggest that the physiological activity of B. japonicum cells changes after storage. Practical implications for inoculant quality control are discussed.

Quantitative determination of endotoxins released by bacterial biofilms.

Residual endotoxins, commonly associated with bacterial biofilms colonizing reusable medical devices have been associated with pyrogenic reactions in patients. We have used a quantitative, sensitive and reproducible kinetic chromogenic adaptation of the Limulus Amebocyte Lysate assay to assess endotoxin recovery from an in-vitro bacterial biofilm. The 'recovery method' was based on a combination of physical treatment (vortexing and sonication) and chemical treatment (immersion in recovery solution). Five recovery solutions were investigated. The recovered endotoxin was greater when the biofilm was treated with a 1% SDS solution. The sensitive and reproducible method we have developed should allow the recovery and measurement of biofilm bacterial endotoxins on implanted and colonized medical devices. Moreover, the amount of endotoxin was sufficient (> 1000 endotoxin units/cm2 of substrate) to enable a substantial reduction by sterilization processes, the efficiency of which on biofilm endotoxins has yet to be proven.

TURBISCAN MA 2000: multiple light scattering measurement for concentrated emulsion and suspension instability analysis.

Emulsion or suspension destabilisation often results from coalescence or particle aggregation (flocculation) leading to particle migration (creaming or sedimentation). Creaming and sedimentation are often considered as reversible, while coalescence and flocculation spell disaster for the formulator. Thus, it is of prime importance to detect coalescence or cluster formation at an early stage to shorten the ageing tests and to improve the formulations. This work mainly concerns the independent and anisotropic scattering of light from an emulsion or suspension in a cylindrical glass measurement cell, in relation with the optical analyser TURBISCAN MA 2000. The propagation of light through a concentrated dispersion can be used to characterise the system physico-chemical stability. Indeed, photons undergo many scattering events in an optically thick dispersion before escaping the medium and entering a receiver aperture. Multiple scattering thus contributes significantly to the transmitted and backscattered flux measured by TURBISCAN MA 2000. We present statistical models and numerical simulations for the radiative transfer in a suspension (plane or cylindrical measurement cells) only involving the photon mean path length, the asymmetry factor and the geometry of the light receivers. We further have developed an imaging method with high grey level resolution for the visualisation and the analysis of the surface flux in the backscattered spot light. We compare the results from physical models and numerical simulations with the experiments performed with the imaging method and the optical analyser TURBISCAN MA 2000 for latex beads suspensions (variable size and particle volume fraction). We then present a few examples of concentrated emulsion and suspension instability analysis with TURBISCAN 2000. It is shown that the instrument is able to characterise particle or aggregate size variation and particle/aggregate migration and to detect these phenomena much more earlier than the operator's naked eye, especially for concentrated and optically thick media.

Influence of skull anisotropy for the forward and inverse problem in EEG: simulation studies using FEM on realistic head models.

For the sake of realism in the description of conduction from primary neural currents to scalp potentials, we investigated the influence of skull anisotropy on the forward and inverse problems in brain functional imaging with EEG. At present, all methods available for cortical imaging assume a spherical geometry, or when using realistic head shapes do not consider the anisotropy of head tissues. However, to our knowledge, no study relates the implication of this simplifying hypothesis on the spatial resolution of EEG for source imaging. In this paper, a method using finite elements in a realistic head geometry is implemented and validated. The influence of erroneous conductivity values for the head tissues is presented, and results show that the conductivities of the brain and the skull in the radial orientation are the most critical ones. In the inverse problem, this influence has been evaluated with simulations using a distributed source model with a comparison of two regularization techniques, with the isotropic model working on data sets produced by a nonisotropic model. Regularization with minimum norm priors produces source images with spurious activity, meaning that the errors in the head model totally annihilate any localization ability. But nonlinear regularization allows the accurate recovery of simultaneous spots of activity, while the restoration of very close active regions is profoundly disabled by errors in the head model. We conclude that for robust cortical source imaging with EEG, a realistic head model taking anisotropy of tissues into account should be used.

Thorium excretion in feces by mineral sands workers.

An attempt has been made to correlate the thorium excreted in the feces of two male workers in the monazite section of a mineral sands dry separation plant over a ten-day period with personal air sampling measurements. The air-borne radioactivity was measured on a daily basis using a total (inspirable) dust filter, an integrating personal dosimeter, and a personal cascade impactor. The thorium content of the feces was measured using inductively coupled plasma mass spectrometry. The results suggest that thorium fecal analyses are able to detect acute and chronic exposures to the inhalation of thorium bearing dusts and to confirm the amount of inhaled thorium predicted from air sampling programs and metabolic models.

[Premature infants weighing less than 1000 grams: mortality, morbidity and short-term neurologic outcome]. / Le prématuré de moins de 1,000 grammes: mortalité, morbidité et devenir neurologique à court terme.

The outcome of 60 premature infants weighing less than 1,000 g at birth and consecutively born during the years 1986 to 1988 is reported. Forty-two (70%) of them were inborn. The overall mortality rate was 42%, but only 26% in the inborn group instead of 78% in the outborn group (P less than 0.001). The mortality rate was higher for the appropriate for gestational age infants (56%) than for the growth retarded infants (14%, P less than 0.01). The main neonatal problems were the following: hyaline membrane disease (63%), patent ductus arteriosus (7%), bronchopulmonary dysplasia (8%), necrotizing enterocolitis (15%), intraventricular hemorrhages (45%) and periventricular leukomalacia (12%). Twenty percent (7/35) of the surviving infants showed abnormal neurodevelopmental outcome, with only one (3%) having major handicap. No correlation was found between gestational age and neuro-developmental outcome.

The rat biliary and urinary metabolism of the N6-methylated derivative of elliptinium acetate, and antitumor agent.

The rat biliary and urinary metabolism of N2,N6-dimethyl-9-hydroxyellipticinium (an N6-methyl derivative of elliptinium acetate, an antitumor agent) is reported. Two main metabolites have been identified: the glucuronide and sulfate derivatives by conjugation of the hydroxy group at position 9. Excretion profiles in bile and urine are also given. It has to be noted that no metabolite corresponding to a demethylation at the indolic nitrogen has been identified. However, the evidence for an increased concentration of the oxidized form of glutathione in bile during the drug excretion supports the hypothesis of an oxidative metabolism of this drug in rat liver.

The biooxidation of cytotoxic ellipticine derivatives: a key to structure-activity relationship studies?

In the family of ellipticine derivatives, those with an amino-phenol or a masked amino-phenol structure are among the most cytotoxic compounds. Preliminary studies on 9-hydroxy- or 9-methoxyellipticines have shown that these molecules behave as "pro-alkylating" agents. In order to rationalize the "biooxidative alkylation" process for various ellipticine derivatives, we report in the present article (i) their electrochemical oxidation parameters, (ii) their biochemical oxidation, (iii) the ability of the oxidized forms to form adducts with nucleophiles, (iv) the biological activities, and (v) the electronic properties of oxidized forms. We present some possible correlations between the oxidizability, the electrophilicity of the oxidized derivatives, and the biological activities of the corresponding drugs.

Peroxidase-catalysed oxidation of N2,N6-dimethyl-9-hydroxyellipticinium acetate. Evidence for the formation of an electrophilic quinone-iminium derivative.

The activation of N2,N6-dimethyl-9-hydroxyellipticinium acetate (DMHE) by a peroxidase-H2O2 system leads to a reactive orthoquinone, or in the presence of a nucleophile like alanine, to adducts with a proposed benzoxazole structure. The stoichiometric and pH metric studies support the generation of a bicationic electrophilic intermediate, namely a quinone-iminium. Since no N6-demethylation occurs during the oxidation process, DMHE is not a prodrug of Celiptium (N2-methyl-9-hydroxy-ellipticinium acetate), but the high electrophilic properties of the species generated might explain its great cytotoxicity and antitumor properties. These results extend the possibility for N6-methyl ellipticine derivatives of a biooxidative activation which can play a role in their cytotoxicity.

Oxidative biotransformation of the antitumour agent elliptinium acetate: Structural characterization of its human and rat urinary metabolites.

The electrophilic properties of the antitumour drug N(2)-methyl-9-hydroxyellipticinium acetate (Celiptium) are revealed by the detection of thiol-conjugate metabolites in man and rat urine. Besides the unchanged drug and its glucuronide, the cysteinyl- (in man) and the N-acetylcysteinyl- (in man and rat) conjugates have been unambiguously characterized using NMR, UV and mass spectral data. The urinary excretion profile exhibits total excreted products of 21% (in man) and 9% (in rat) with respect to the administered dose. The unchanged drug is found to be the major excreted compound from urine in both species (17% in man, 6.3% in rat); whereas the glucuronide (2.6% in man, 1.5% in rat), cysteinyl- (1.3% in man) and N-acetylcysteinyl- (0.2% in man, 1.2% in rat) conjugates represent the minor excreted compounds. The presence of the latter thio-conjugates provides an indirect proof of the in vivo generation of an oxidized intermediate form of the administered drug.

[Supplementary parenteral nutrition in premature infants. Adaptation to amino acid intake]. / Alimentation parentérale supplétive chez le prématuré. Adaptation de l'apport en acides aminés.

The authors report a controlled study of the use of 2 types of amino-acid solutions for premature infants nutrition in the first days of life, one of the solution (solution I) being adapted for prematures. The average amino-acid blood levels in prematures receiving solution I were close to those observed in cord blood; Plasma taurine, alanine and arginine concentrations were significantly lower with normalized levels of aromatic amino-acids, lysine, taurine and proline; serum ammonia level was also lower. This study shows that using an amino-acid solution adapted to prematures as a supplement to parenteral nutrition during the first days of life allows to progressively increase the nitrogen intakes without inducing dangerous plasma levels of some amino-acids.

[Demonstration of an oxidative biotransformation of 9-methoxyellipticine. Comparison with the case of 9-hydroxyellipticine]. / Mise en évidence d'une biotransformation oxydante de la méthoxy-9-ellipticine. Comparaison avec le cas de l'hydroxy-9-ellipticine.

Evidences for the formation of the glutathione-hydroxyellipticine adduct during the rat metabolism of 9-methoxyellipticine are provided. These data suggest that such a cytotoxic molecule might behave as a pro-alkylating agent in vivo.

Ribose as the preferential target for the oxidized form of elliptinium acetate in ribonucleos(t)ides. Biological activities of the resulting adducts.

The covalent binding of the oxidized form of elliptinium acetate, an antitumor drug, to various ribonucleos(t)ides is described. In the absence of a strong nucleophile on the bases, e.g., a sulfhydryl group, the main target of this quinone imine derivative is the sugar moiety. With unmodified regular bases, the first electrophilic addition always occurs on the 2'-oxygen of ribose (more slowly for pyrimidine than for purine); in a second step, cyclization of the reoxidized product leads to a spiro derivative: only one stereoisomer is detected with purine nucleoside; the other stereoisomer appears as a minor product (10-20%) with nucleotides and pyrimidine nucleosides. With modified bases, no change is observed except for bases exhibiting an additional strong nucleophilic center: oxidized elliptinium alkylates thioguanine and thioguanosine on the sulfur atom and in this last case not on the ribose moiety. All spiro derivatives are less cytotoxic than the parent compound even if the base is an antimetabolite (azauridine); however, thio-elliptinium adducts maintain high cytotoxicity.

[Cesarean section before the end of 32 weeks' gestation. Apropos of 91 neonatal case reports]. / Les césariennes avant 32 semaines de gestation révolues. A propos de 91 observations neonatales.

78 cesarean sections (CS) were performed before 32 weeks of gestation over a period of six years in a obstetric clinic; 91 premature infants were born; the rate of CS at this period of time represented 0,47% of total birth. 84 premature infants were transferred to the neonatal unit located in the same clinic; 3 were dead in utero and 4 just after delivery. 69 infants survived (78%) but 6 had severe sequelae (spastic diplegia, epilepsy and RLF) at one year of age and 7 had minor sequelae.

Female discrimination of male dominance by urine odor cues in hamsters.

Female hamsters have been found to differentially respond to the odors of dominant as opposed to subordinate males. This study reexamined these responses in an olfactometer allowing the females to choose between urinary odors obtained from males differing in dominance status and clean air source. The behavior of the estrous females was consistent with previous research which indicated that such females exhibit a preference for stimuli obtained from dominant males. Contrary to previous findings in a two-choice apparatus, diestrous females failed to prefer the odors of subordinates. These females spent significantly more time in the area infused with unscented air. These data emphasize the importance of odor cues as they relate to male attractivity and possibly mate choice. They also underscore the need to allow animals to avoid conspecific odors in order to reduce the possibility of forcing animals into an unrealistic choice situation.