Separation of isoenzymatic forms of human serum galactosyltransferase by chromatofocusing and isoelectric focusing. Application to cancerology

Chromatofocusing is used to separate the multiple isoenzyme forms of human serum galactosyltransferase. At least 11 major peaks of activity are observed in normal sera, which are eluted between pH 4.3 and 6.9; a fraction of activity is eluted above pH 7.0. The normal patterns are compared with those obtained with sera from cancer patients and with an ascitic fluid. Chromatofocusing appears as resolutive as agarose isoelectric focusing.     

Malformation uropathies and multiple malformation syndromes

The authors, from their experience emphasize the associated malformations' frequency in major congenital urinary tract malformations (26,9%). It is essential to recognize in these multiple defects some certified syndromes - inherited or not. The most associations are still unknown, nevertheless the genetic counselling require an accurate diagnosis.     

Biological and physical properties of a beta-endorphin analog containing only D-amino acids in the amphiphilic helical segment 13-31

Our approach to the modeling of beta-endorphin has been based on the proposal that three basic structural units can be distinguished in the natural peptide hormone: a highly specific opiate recognition sequence at the N terminus (residues 1-5) connected via a hydrophilic link (residues 6-12) to a potential amphiphilic helix in the C-terminal residues 13-31. Our previous studies showed the validity of this approach and have demonstrated the importance of the amphiphilic helical structure in the C terminus of beta-endorphin. The present model, peptide 5, has been designed in order to evaluate further the requirements of the amphiphilic secondary structure as well as to determine the importance of this basic structural element as compared to more specific structural features which might occur in the C-terminal segment. For these reasons, peptide 5 retains the three structural units previously postulated for beta-endorphin; the major difference with regard to previous models is that the whole C-terminal segment, residues 13-31, has been built using only D-amino acids. In aqueous buffered solutions as well as in 2,2,2-trifluoroethanol-containing solutions, the CD spectra of peptide 5 show the presence of a considerable amount of left-handed helical structure. Enzymatic degradation studies employing rat brain homogenate indicate that peptide 5 is stable in this milieu. In delta- and mu-opiate receptor-binding assays, peptide 5 shows a slightly higher affinity than beta-endorphin for both receptors while retaining the same delta/mu selectivity. In opiate assays on the guinea pig ileum, the potency of peptide 5 is twice that of beta-endorphin. In the rat vas deferens assay, which is very specific for beta-endorphin, peptide 5 displays mixed agonist-antagonist activity. Most remarkably, peptide 5 displays a potent opiate analgesic effect when injected intracerebroventricularly into mice. At equal doses, the analgesic effect of peptide 5 is less than that of beta-endorphin (10-15%) but longer lasting. In conjunction with our previous model studies, these results clearly demonstrate that the amphiphilic helical structure in the C terminus of beta-endorphin is of predominant importance with regard to activity in rat vas deferens and analgesic assays. The similarity between the in vitro and in vivo opiate activities of beta-endorphin and peptide 5, when compared to the drastic change in chirality in the latter model, demonstrates that even a left-handed amphiphilic helix formed by D-amino acids can function satisfactorily as a structural unit in a beta-endorphin-like peptide.     

Antibodies to Dopamine: Radioimmunological Study of Specificity in Relation to Immunocytochemistry

Abstract: Two classes of anti-3,4-dihydroxyphenylethylamine (dopamine) antibodies were raised in rabbits using dopamine conjugated to albumin either via formaldehyde or via glutaraldehyde. Each was usable for immunohistochemical detection of dopamine neurons provided that the tissue was fixed by the homologous cross-linking agent. However, anti-dopamine-glutaraldehyde antibodies turned out to be of more general use because of the better fixative properties of glutaraldehyde which fixed dopamine in rat and in teleost, whereas formaldehyde only worked in lower vertebrates (such as goldfish) and not in rat brain. The specificity of antidopamine-glutaraldehyde antibodies was firmly established by competition experiments in equilibrium dialysis, using an immunoreactive tritiated derivative synthesized by coupling dopamine to N -α-acetyl-L-lysine N -methylamide via glutaraldehyde. Specificity studies in vitro and immunohistological results demonstrating the specific staining of dopaminergic neurons were found to correlate well.     

α-Ketoglutarate and Malate Uptake and Metabolism by Synaptosomes: Further Evidence for an Astrocyte-to-Neuron Metabolic Shuttle

This study was undertaken to provide further evidence relevant to the hypothesis that astrocytes supply one or more citric acid cycle intermediates to synaptic terminals, thereby serving an anaplerotic function necessitated by the synthesis and release of amino acid neurotransmitters. In our experiments, two populations of synaptosomes obtained from the brain of rats were separated from myelin and mitochondria by using Percoll to generate continuous density gradients. Both synaptosomal populations readily accumulated 14C-labelled alpha-ketoglutarate and L-malate by high-affinity transport systems. Hofstee plots of uptake velocity as a function of substrate concentration were highly nonlinear, indicating that uptake was mediated by two or more carriers, or was subject to negative cooperativity. At least one carrier was selective for alpha-ketoglutarate and another for malate, whereas a third carrier appeared to be present which transported both substrates. At low concentrations (approximately 1 microM), alpha-ketoglutarate transport was almost totally Na+-dependent, whereas malate uptake exhibited little Na+-dependency. The transport of alpha-ketoglutarate was associated with a net influx, and therefore was not due to a homoexchange process. alpha-Ketoglutarate and malate were metabolized rapidly to glutamate and aspartate, respectively, by both synaptosomal preparations; however, in all cases, label accumulated in gamma-aminobutyric acid rather slowly. The incorporation of label into glutamine from alpha-ketoglutarate was much greater in the high-density synaptosomes that in low-density synaptosomes, an indication that the former contained a higher proportion of astrogliasomes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Kinetics of inhibition in propionic acid fermentation

The inhibitory effect of propionic acid P and biomass concentration X is studied in batch and continuous fermentations with cell recycle.In batch fermentations, the specific growth rate decreases and cancels out at a critical propionic acid concentration Pc ₁; the formerly decreasing specific production rate becomes constant after Pc ₁ and cancels out when a second critical propionic acid concentration Pc ₂ is reached.In continuous fermentation with cell recycle, a similar inhibition is observed with biomass. The specific rates decrease and become constant at a critical biomass concentration Xc. They cancel out at different high biomass concentrations.In both cases, the specific production rate can be related to the specific growth rate by the Luedeking and Piret expression: =+, [1], where the constants and are determined by the fermentation parameters.List of Symbols t h time - X kg/m³ biomass concentration - P kg/m³ propionic acid concentration - A kg/m³ acetic acid concentration - S kg/m³ lactose concentration - dX/dt kg/(m³h) instantaneous rate of cell growth - dP/dt kg/(m³h) instantaneous rate of propionic acid production - h^–1 specific growth rate - h^–1 specific propionic acid production rate - D h^–1 dilution rate     

The reserve proteins in the cells of mature cotyledons ofLupinus albus var.Lucky

Summary The nuclear DNA content of cotyledonary cells of two lupin seeds (L₁ and L₂) with markedly different total protein content, were investigated by scanning cytophotometry. Both seeds had polyloid nuclei with DNA levels varying between 8 C and 64 C, the majority being either 16 C or 32 C. The highest DNA levels were found in the abaxial and central cotyledonary zones of both seeds; seed L₂ had a higher ploidy level than L₁. It is shown that the volume of condensed chromatin (chromocenters) increased proportionally with the DNA content of the nucleus. A comparison was made between the distribution of protein, previously determined byLe Gal andRey (1986) and the DNA throughout the cotyledon. The L₂ seed, which has the highest total protein and the highest protein content per cell, also exhibited the greatest DNA content per cell. For both seeds, the r-value for association of DNA and protein content per cell was highly significant (0.98).     

Leishmaniasis in Bolivia. II. The involvement of Psychodopygus yucumensis and Psychodopygus llanosmartinsi in the selvatic transmission cycle of Leishmania braziliensis braziliensis in a lowland subandean region

An epidemiological survey of the vectors of cutaneous leishmaniasis ("espúndia" type) was carried out in the Alto Beni region of Bolivia, an area of Andean foothills at the Eastern limit of the Amazonian lowlands. The climate is typical wet tropical (15 degrees S latitude). Anthropophilic phlebotomine sandfly species were sampled at 20 sites, all forested. The importance of species from the Psychodopygus group, already suspected as a vector in the transmission of Leishmania from the braziliensis complex, was confirmed by: the aggressiveness and diversity of the species encountered (83% of catches, nine species), the discovery of a new anthropophilic species, P. yucumensis and the isolation of a strain of Leishmania braziliensis braziliensis indistinguishable from human strains from the same area, from two species, P. llanosmartinsi and P. yucumensis.     

Characterization and expression of collagen-like genes in Drosophila melanogaster

We have used a cloned chicken collagen cDNA sequence to help identify hypothetic members of the collagen gene family from Drosophila melanogaster. Several experimental evidences have been obtained which indicate that the Drosophila genome contains numerous collagen-like sequences. We have characterized in more detail ten distinct DNA sequences that hybridized strongly to the heterologous collagen probe. By in situ hybridization we have shown that these sequences are dispersed throughout the Drosophila genome. Two of them are shown to originate from the previously described DCg 1 and DCg 2 collagen genes. In other respects, we show that in addition to DCg 1 and DCg 2, at least five putative collagen genes are expressed during the Drosophila lifetime. These genes are unique, and some of them are seen to be transcribed into different size classes of mRNAs. Additionally, the data presented so far demonstrate that the expression of these genes is regulated temporally and/or quantitatively during the Drosophila life cycle.     

Intragranular vesicles: new organelles in the secretory granules of adrenal chromaffin cells

Summary Chromaffin granules from bovine adrenal medullary chromaffin cells have been found to contain small vesicular structures bounded by unit membranes. Detection of these intragranular vesicles within intact cells requires the use of quick-freezing methods. The intragranular vesicles are labile to fixation by aldehydes which explains why they have not been described in intact cells until now. They are found in approximately 60% of the dense-core chromaffin granules in cells and 85% of isolated granules. They are usually clustered in groups of one to as many as five between the core and the inner surface of the granule membrane. The intragranular vesicles are independent vesicles in that they do not appear as simple invaginations of the granule membrane in either serial thin-section or freeze-etch views. Furthermore, they are released from the cell along with granule contents during nicotine-induced secretion of catecholamines. The structural heterogeneity provided by the intragranular vesicles may be related to the functional heterogeneity of granule contents observed in many recent biochemical studies.