Euonymus europaeus lectin as an endothelial and epithelial marker in canine tissues.

The Euonymus europaeus agglutinin (EEA) is an endothelial marker in mammalia. In canine tissues, 4 types of endothelial cells (general, nervous, arterial, hepatic) were identified by the presence of the EEA receptor and by its sensitivity to neuraminidase enhancement. In adult dogs, EEA binding saccharides had endothelial or epithelial distributions and reactivities similar to those described for human tissues. Different EEA reactivities were observed between fetal, neonatal and adult canine tissues mainly at the arterial level. These findings suggest that the development of the binding sites is not identical in dog and man. Related lectins and monoclonal antibodies were used to characterize the EEA binding site, and the probable structure of the EEA binding saccharide in endothelial cells appeared to be alpha Gal (1,3) beta Gal (1,4) GlcNAc.

Lithium transport in the mouse brain.

Using the stable isotopes of lithium 6Li and 7Li, and the nuclear reaction 6Li(n,alpha)3H for detection, we have studied the isotopic exchange of lithium in various areas of the mouse brain and in the mouse plasma, under conditions of constant concentration of total lithium. The neutron irradiations were performed using 'cold' neutrons, at the European Institute Von Laue-Langevin. The nuclear reaction track densities were determined using an automatic image analyser. In the plasma, the isotopic ratios, 6Li/7Li, were measured using 'Secondary Ion Mass Spectrometry'. The concentration of total lithium in the plasma was kept close to 0.28 mM. The brain concentration of total lithium (referred to the tissue water content) ranged from more than 2 mM in the thalamus to less than 0.65 mM in the white matter of the cerebellum. The Nernst potential of lithium thus ranged from approx. -50 to approx. -20 mV, which means that lithium is probably not far from electrochemical equilibrium between brain cells and plasma. At any moment, the isotopic abundance of 6Li (ratio of 6Li to total lithium) in the different brain areas, were not significantly different from one another. The time-course of the isotopic abundance of 6Li in the brain was fitted by the composition of two exponential terms. The time-course of the isotopic abundance of 6Li in the plasma was also fitted by the composition of two exponential terms. These analytic curves (for the brain and for the plasma) were not significantly different from each other, at the precision of the measurements. This means that the isotopic equilibration of lithium between brain and plasma is almost instantaneous (i.e. accomplished in a few min at the most).

A method for the analysis of lithium in liquid droplets using isotopic dilution and SIMS measurements.

An absolute, fairly rapid method for the analysis of lithium in liquid droplets is described. It is based on the isotopic dilution of a 6Li (or 7Li)-enriched lithium salt, and on the measurement of isotopic ratios using Secondary Ion Mass Spectrometry. The sensitivity is well adapted to the analysis of lithium in minute volumes of plasma taken from patients suffering from manic-depressive psychosis.

Imaging the distribution of the stable isotopes of nitrogen 14N and 15N in biological samples by "secondary-ion emission microscopy".

Thanks to the "secondary-ion emission microscope" (CAMECA IMS 300), we have been able to image the distribution of the stable isotopes of nitrogen 14N and 15N in sections of plant roots (spatial resolution better than 1 micron), as well as to estimate the relative concentrations of these isotopes. The plants used (Lupinus spec.) originated from seeds with natural (i.e., 14N) nitrogen and had been fed for a few days with [15N]-nitrate before sampling. We have found in root sections of 6-day-old plants (prepared at 5 mm from the root tip) a clear-cut regionalization of the distribution of 15N between the vascular cylinder and the cortex. The latter contained approximately 5% 15N (of total nitrogen), whereas the relative concentration of the heavy isotope in the vascular cylinder was significantly lower. The observed concentration difference is probably due to the Casparian strip, which is a barrier for the apoplastic diffusion of solutes from the cortex to the vascular cylinder.

Lithium distribution in the brain of normal mice and of "quaking" dysmyelinating mutants.

Using nuclear reaction 6Li(n, alpha)3H and dielectric detectors, we have studied the distribution of Li in the brain of adult mice, following Li treatment of the animals. Two strains of animals were used in parallel: "quaking" dysmyelinating mutants and normally myelinated controls. The distribution appeared to be sharply regionalized in the brain of the normal mice (higher Li concentration in the gray rather than in the white matter, with the area postrema being particularly Li rich). In contrast, the Li distribution was practically homogeneous in the brain of the quaking dysmyelinating mutants, with a mean Li concentration comparable to that in the gray matter of the controls. The present method of Li detection has made it possible to estimate the Li equilibrium potentials (nerve cells with regard to plasma) in the different brain substructures. The results are consistent with (a) Li being actively extruded from nerve cells in all the cases and (b) myelination decreasing the relative importance of the passive component of Li transport in the nerve cells, as compared with the active component.

[Compartmental analysis of 6Li/7Li isotope exchange in equilibrium conditions in mouse plasma]. / Analyse compartimentale de l'échange isotopique 6Li/7Li en conditions stationnaires dans le plasma de la souris.

The compartmental analysis of lithium in the mouse plasma has been performed using the stable isotopes, 6Li and 7Li, as tracers. The animals were kept under stationary conditions (concentration of total lithium in plasma maintained equal to 0.28 mM) during the experiment. The isotopic exchange, 6Li/7Li, was described to a good approximation by combining two first-order processes (characteristic parameters: 89 microM and 2.071 X 10(-3) X min-1 for the first one, and 193 microM and 2.215 X 10(-4) X min-1 for the second one). From these kinetic data, it was estimated that the lithium capacities of the plasma and of the cells were 282 and 454 nmol X ml-1, and that the unidirectional fluxes of lithium between plasma and cells and through the kidneys were 0.259 and 0.227 nmol X ml-1 X mn-1. Since the method makes use only of stable, hence harmless, isotopes, one might think of extending it to direct experimentation in man.

Estimation of local kinetic parameters of exchange of lithium in various substructures of the mouse brain, using the 6Li(n, alpha)3H-nuclear reaction.

The time-constant of lithium (Li)-clearance from the plasma was of the order of 2 hr, while the mean time-constant of lithium-clearance from the bulk of the body cells into the plasma was about 10 times this value. The mean time-constant of lithium ion (Li+)-clearance from various brain substructures (corpus callosum, striatum, hippocampus, neocortex) was comparable to the latter (15-25 hr). Comparison of samples where either a slight diffusion or no diffusion at all had occurred, suggest that between the nerve bodies and the trunks, lithium ions are not uniformly distributed.

Quantitative study of the distribution of lithium in the mouse brain for various doses of lithium given to the animal.

Lithium is detected in the mouse brain with the aid of a (n,alpha) nuclear reaction. The resolving power is of a few micron. The detection efficiency is estimated in a first series of experiments with brain sections of progressively increasing thickness. This allows us to make the microlocation of lithium in the brain sections quantitative. Lithium accumulation in the different brain substructures is then measured for increasing lithium doses given to the animals (1--15 meq/kg animal). For measurements made 6 h after the last injection of lithium, it is corroborated that the accumulation of Li is much larger in the areas with cellular bodies of neurons than in those with nerve trunks only, especially for the smaller doses of lithium given as treatment. Whereas the accumulation curve as a function of the Li concentration of the blood is linear for areas with nerve trunks only, it is negatively bent for the areas with cellular bodies. This and previous data allow us to attempt an estimate of the Li content of the cellular bodies only. A saturation effect seems to appear as soon as the Li concentration in the blood is greater than 1 mM.

[Evolution of muscles in Nereidae (Annelida polycheta) during epitoky. I and II. Atokous and epitokous longitudinal fibres (author's transl)]. / Evolution de la musculature des Néréidiens (Annélides polychètes) au cours de l'épitoquie. I et II. Fibres atoques et épitoques des faisceaux longitudinaux.

The longitudinal fibres from atokous Nereis belong to the double oblique striation type. Their thick myofilaments, paramyosinic (about 145 A periodicity) are arranged in an hexagonal lattice, well preserved after a glycerol treatment. 9 to 13 thin filaments form an orbit around one thick filament (ratio: 6-7/1). The contraction occurs in two processes: a sliding filament mechanism, and a shearing mechanism. This second mechanism consists in a parallel shifting of thick filaments, arising their overlap and decreasing their degree of stagger; it induces the increase of the myofibrillar (A-bands) oblique angle from 10-12 degrees in isolated glycerol extracted fibres, to 35-38 degrees in the same fibres after contraction by the action of ATP-solution. The longitudinal fibres from epitokous Nereis or Heteronereis are characterized also by a double oblique striation. The structural aspects of the contraction are similar to these ones occurring in atokous fibres. Nevertheless, the epitokous fibres are different from the atokous fibres by many characteristic points. Their thick myofilaments, with an hexagonous array, are thinner and shorter than these ones from atokous fibres. The contractile material is only present in the cortex. The axis of epitokous fibres is filled with numerous mitochondria, between them numerous glycogen particles have been synthetised. The sarcoplasm of the fiber's coelomic edge is often devoided of myofilaments but it is full of mitochondria and glycogen granules. The nucleus, with a voluminous nucleolus, is no more placed in the fibre axis, but in a lateral sarcoplasm containing ribosomes, glycogen and mitochondria. The important transformations of longitudinal fibres are discussed in connection with the Heteronereis locomotor behaviour, very different from this one of the atokus Nereis. Particularly, it seems that the abundance of glycogen and mitochondria in epitokous muscles allows a high contraction frequency. The decrease of the diameter and length from the thick filaments should be set in relation with the augmentation of the contraction's swiftness. These results are very similar to these ones occuring in Syllidae with the stolonization mode of reproduction. The Syllis stolonial fibres present the same characteristics than the Nereis epitokous fibres.

Detection of stable isotopes of lithium or boron with the help of A (n,alpha) nuclear reaction. Application to the use of 6Li as a tracer for unidirectional flux measurements and to the microlocalization of lithium in animal histologic preparations.

In the particular case of boron and lithium we examine the possibilities of using stable isotopes for experiments of isotopic labelling and microlocalization, as no radioisotopes exist. The detection is made with the help of a specific nuclear reaction, using homogeneous detectors. The first experimental applications are given: transepithelial fluxes of lithium (frog skin) have shown Liefflux values larger than the influx ones. Detailed microlocalization of lithium have been made on histological preparations of mice having received lithium treatment: particularly important contents are found in the hypophysis, the salivary glands, the bladder, the kidney (especially the pelvis), the intestinal system and certain parts of the brain (particularly the hippocampus); the liver, however remains very poor in lithium. Physiological implications are examined.