Liver fatty acid-binding protein in two cases of human lipid storage

Summary FABPs in the various tissues play an important role in the intracellular fatty acid transport and metabolism. Reye's syndrome (RS) and multisystemic lipid storage (MLS) are human disorders characterized by a disturbance of lipid metabolism of unknown etiology. We investigated for the first time L-FABP in these two conditions. Affinity purified antibodies against chicken L-FABP were raised in rabbits, and found to cross-react specifically with partially purified human L-FABP. L-FABP content in liver samples of two patients with RS and MLS was investigated by immuno-histochemistry, SDS-PAGE and ELISA. L-FABP immuno-histochemistry showed increased reactivity in the liver of RS patient and normal reactivity in MLS liver. L-FABP increase in RS liver was confirmed by densitometry of SDS-PAGE and ELISA method. By these two methods the increase amounted to 180% and 199% (p < 0.02), respectively, as compared to controls. A possible role of L-FABP in the pathogenesis of RS is discussed.     

Body size increase in insular rodent populations: a role for predators?

Insular mammalian populations living in areas of small size are often characterized by a drastic change in body mass compared to related continental populations or species. Generally, small mammals (less than 100 g) evolve into giant forms while large mammals (up to 100 g) evolve into dwarf forms. These changes, coupled with changes in other life, behavioural, physiological or demographic traits are referred to generally as the insular syndrome. We tested in this study the relative contribution of three factors — area of island, numbers of competitor species and number of predator species — to changes in body size of the woodmouse (Apodemus sylvaticus) in the Western Mediterranean Sea. Our results, based on a comparative analysis using the phylogenetic independent contrasts method, indicate that the increase in body size is related both to the decrease of island size and to the lower number of predator species. A decrease of competitor species does not seem to have an important effect.     

Interaction of diphtheria toxin fragment A and of elongation factor 2 with Cibacron blue

Diphtheria toxin fragment A interacts with Cibacron blue in solution, although it is not retained by blue Sepharose columns. Difference spectral titration of fragment A with the dye gives a dissociation constant of the order of 10^–5 M and a 11 stoichiometry for the complex. In equilibrium dialysis experiments Cibacron blue behaves as a competitive inhibitor of the binding of NAD to diphtheria toxin fragment A. The dye inhibits in a non-competitive way the fragment A-catalysed transfer of ADP-ribose from NAD to elongation factor 2 (EF2). By affinity chromatography on blue Sepharose a binding of EF2 and of ADP-ribosyl-EF2 with the dye is also demonstrated. GDP, GTP and GDP(CH₂)P are able to displace EF2 from blue Sepharose.     

Nucleotide pool and the proliferative process: an NMR study of the liver regeneration

The metabolic changes occurring during liver regeneration after partial hepatectomy have been followed by examination of the perchloric extracts by means of NMR spectroscopy. Proton spectra show an abrupt decrease of glycogen, glucose and nucleotides, which are essentially ribonucleotides, in the first hours after hepatectomy. Nucleotides begin to store up again in the third day after hepatectomy, while glucose and glycogen storage builds up from the second day. 31P data evidence a sharp drop of phosphomonoesters, i.e. monophosphosugars (including AMP) and phosphocholine, and phosphodiesters, i.e. GPC and GPE, soon after hepatectomy and a recovery of the initial levels approximately at the 60th hour and a further increase of PDE at later times. The NMR findings are in agreement with the biochemical knowledge of the course of liver regeneration.     

Expression of HOX homeogenes in human neuroblastoma cell culture lines

Mammalian genes containing a class-I homeobox (HOX genes) are highly expressed in the embryonic nervous system. As a first step towards the molecular analysis of the role these genes play in neural cells, we studied the expression of four human HOX genes in five neuroblastoma (NB) cell lines - SK-N-BE, CHP-134, IMR-32, SK-N-SH and LAN-1 - during the process of differentiation induced by treatment with retinoic acid (RA). The four genes, HOX1D, 2F, 3E and 4B, located at corresponding positions in the four HOX loci, share a high degree of sequence similarity with the Drosophila Deformed homeotic gene and constitute a homology group, group 10. One of these genes, HOX1D, is not expressed in the cells used, whereas the other three are highly expressed in untreated and RA-induced NB cells, even though the expression pattern in the various lines is slightly different for the three genes. Our analysis reveals a complex and specific expression pattern in these lines, paving the way to an identification of different NB-cell populations by means of specific HOX gene expression schemes. On the other hand, in every line studied, morphological maturation toward a neuronal differentiated phenotype appears to be associated with increased HOX gene expression.     

Voltammetric studies on the electrochemical behaviour of membrane-entrapped hemes

Summary The electrochemical behaviour of Fe(III)-protoporphyrin IX entrapped into a cellulose triacetate membrane has been investigated by cyclic voltammetry. The physical entrapment into a solid matrix does not modify the redox properties of the entrapped berries, which also act as efficient promoters in the electrochemistry of cytochromec. Such a system represents a promising example of a simple solid-state promoter, and stimulates further investigations in order to obtain more complex systems that may be of significance for basic and applied bioelectrochemistry.     

A hemagglutinin specific for sialic acids in a rat brain synaptic vesicle-enriched fraction

A hemagglutinating activity was detected in a synaptic vesicle-enriched fraction prepared from adult rat brain, using trypsinized glutaraldehyde-fixed rabbit erythrocytes. The specific activity of the fraction, in two series of experiments, was 7.5 and 16-fold higher than in the other subcellular fractions. The activity was absent from the synaptosome cytosol. In a study using twenty-five different carbohydrates and glycoproteins, best inhibitors were N-acetylneuraminic acid and N-glycolylneuraminic acid, together with bovine submaxillary mucin and a glycopeptide fraction prepared from rabbit erythrocyte membranes. The activity was thermolabile and very sensitive to proteolytic enzymes (but insensitive to neuraminidase) indicating that a protein (agglutinin) is responsible for the activity. Experiments using detergents and high ionic strength showed that the agglutinin is tightly bound to membranes, inactivated by the so-called non denaturing detergents, and stable in diluted sodium dodecyl sulphate. Hypotheses are discussed on the possible function of the agglutinin.     

Guaianolides and lignans from Centaurea solstitialis subs Schouwii

Aerial parts of Centaurea solstitialis subs schouwii afforded the guaianolides cynaropicrin and aguerin B and the lignans arctigenin and matairesinol. The structure of a third guaianolide previously found also in Centaurea behen was revised.     

Anthracycline gels. Preparation and some physico-chemical properties

Gels have been prepared from aqueous solutions of anthracyclines by addition of salts. The gels are thixotropic and thermally reversible. They are stable for several months in the refrigerator and for long times even at room temperature. The gel-solution transition (melting) temperature depends on the concentration of the anthracycline and on the concentration and nature of the added salt. The melting has been followed by 1H-NMR. Only weak intermolecular interactions (stacking and hydrogen bonds) originate the drug network, within which the solvent is entrapped. 1H-NMR and polarimetric data suggest a stacked helical arrangement of the anthracycline molecules. The gelation process is cooperative.