A fast and simple radiometric assay for adenosine deaminase using reversed-phase thin-layer chromatography

A new quantitative radiometric assay for adenosine deaminase is described. The reaction conditions are similar to those used in other radioassays and are shown to result in an activity which increases linearly with time and with enzyme concentration. An original feature of the technique resides in the use of reversed-phase thin-layer chromatography to separate adenosine from inosine. The separation is complete, fast, and reproducible. Both compounds can be recovered almost quantitatively from the plates. The assay is very simple and allows the determination of up to 36 samples in 3 h.     

Attribution des signaux de résonance magnétique nucléaire-13c de disaccharides peracétylés dans la série du D-glucose

Selective, double irradiation allows the assignment of most ¹³C-n.m.r. signals in a series of per-O-acetyl disaccharides composed of two D-glucose residues linked α-(1→3), β-(1→3), α-(1→4), β-(1→4), α-(1→6), β-(1→6), and α,α-(1→1). The main influences that affect the chemical shifts are discussed and the spectra of β-cellobiose octaacetate and β-maltose octaacetate are compared to those of cellulose and amylose triacetate, respectively, to show the possibilities and limitations of a disaccharide model for the interpretation of the ¹³C-spectrum of a polymer.     

L'encapsulation hémocytaire expérimentale chez le lépisme Thermobia domestica

The introduction of inert foreign objects into the thorax of the thysanuran Thermobia domestica provoked the formation of a cellular capsule, the development and fine structure of which were examined.Encapsulation at first simply results from the accumulation of blood cells around the implant. It is possible to distinguish 48 hr later four regions in the cellular capsule: (1) An exterior layer including normal haemocytes. (2) An intermediate layer formed by homogeneous intercellular electron-dense material and by stretched haemocytes. These haemocytes have numerous microtubules, without any granular particles, and are linked together by desmosomes. (3) An interior layer of cells in the process of necrosis and rich in lysosomes. (4) A very thin limiting layer tentatively interpreted as melanin.The large number of haemocytes devoid of the specific features of the fibroblasts and the very important reduction of the acellular material without collagen fibrils distinguish clearly the cellular capsules of the Insecta from the granuloma of the Vertebrata and other groups.     

A stochastic model of cell aggregation under planar flow in the dilute regime

Models of the adhesion of a population of cells in a plane flow are developed, considering the dilute regime. Cells considered as rigid punctual entities are virtually injected at regular times within a plane channel limited by two fixed planes. The pressure profile is supposed to be triangular (constant gradient), in accordance with the assumptions of a Poiseuille flow. The cell adherence to the channel wall is governed by the balance of forces, accounting for gravity, non-specific physical interactions, such as electrostatic effects (repulsive) and Van der Waals forces (attractive), specific adhesive forces representing the ligand–receptor interactions, and friction between cells and the fluid in the vicinity of the endothelium wall. The spatial distribution of the adhesion molecules along the wall is supposed to be a random event, accounted for by a stochastic spatial variability of the dipolar moments of those molecules, according to a Gaussian process. Experimental trends reported for the rate of aggregation of L-selectin mediated leukocytes under shear flow are in qualitative accordance with the evolution versus time of adhering cells obtained by the present simulations. The effect of the maximal injection pressure on those kinetics is assessed.     

Essai chimiosystématique sur la tribu des Lotées

A survey of the leaves and flowers of 62 representatives of the tribe Loteae (Leguminosae) showed the presence of several classes of flavonoids: flavonol 7-methyl ethers (rhamnocitrin, rhamnetin), 8-O-substituted flavonols (gossypetin, limocitrin, sexangularetin, corniculatusin), 3′,4′,5′-tri-O-substituted flavonols (myricetin, mearnsetin, syringetin, laricitrin), proanthocyanidins and flavone-C-glycosides. The trisubstitution of the B-ring and the 8-O-substitution of the A-ring allow the definition of a major group including the genera Dorycnium, Bonjeania, Lotus and Tetragonolobus. The presence of proanthocyanidins and 7-O-methylation determine a second group consisting of the genus Anthyllis. Finally, Securigera, on the basis of its flavonoid chemistry, appears to be rather remote from other members of the tribe.     

Impact of Anesthetics on Immune Functions in a Rat Model of Vagus Nerve Stimulation

Vagus nerve stimulation (VNS) has been successfully performed in animals for the treatment of different experimental models of inflammation. The anti-inflammatory effect of VNS involves the release of acetylcholine by vagus nerve efferent fibers inhibiting pro-inflammatory cytokines (e.g. TNF-α) produced by macrophages. Moreover, it has recently been demonstrated that splenic lymphocytic populations may also be involved. As anesthetics can modulate the inflammatory response, the current study evaluated the effect of two different anesthetics, isoflurane and pentobarbital, on splenic cellular and molecular parameters in a VNS rat model. Spleens were collected for the characterization of lymphocytes sub-populations by flow cytometry and quantification of cytokines secretion after in vitro activation. Different results were observed depending on the anesthetic used. The use of isoflurane displayed a non-specific effect of VNS characterized by a decrease of most splenic lymphocytes sub-populations studied, and also led to a significantly lower TNF-α secretion by splenocytes. However, the use of pentobarbital brought to light immune modifications in non-stimulated animals that were not observed with isoflurane, and also revealed a specific effect of VNS, notably at the level of T lymphocytes’ activation. These differences between the two anesthetics could be related to the anti-inflammatory properties of isoflurane. In conclusion, pentobarbital is more adapted than isoflurane in the study of the anti-inflammatory effect of VNS on an anesthetized rat model in that it allows more accurate monitoring of subtle immunomodulatory processes.