RPR 119990, a novel alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid antagonist: synthesis, pharmacological properties, and activity in an animal model of amyotrophic lateral sclerosis

Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptor antagonists are of potential interest for the treatment of certain acute and chronic neurodegenerative diseases, including amyotrophic lateral sclerosis. Here, we describe the synthesis and pharmacological properties of 9-carboxymethyl-4-oxo-5H,10H-imidazo[1,2-a]indeno[1,2-e]pyrazin-2-phosphonic acid (RPR 119990). The compound displaced [3H]AMPA from rat cortex membranes with a K(i) of 107 nM. In oocytes expressing human recombinant AMPA receptors, RPR 119990 depressed ion flux with a K(B) of 71 nM. The antagonist properties of this compound were confirmed on rat native AMPA receptors in cerebella granule neurons in culture and in hippocampal slices where it antagonized electrophysiological responses with IC50 values of 50 and 93 nM, respectively. RPR 119990 antagonized hippocampal evoked responses in vivo, demonstrating brain penetration at active concentrations. RPR 119990 is a potent anticonvulsant in the supramaximal electroshock in the mouse with an ED50 of 2.3 mg/kg 1 h post s.c. administration, giving it a workably long action. Pharmacokinetic studies show good passage into the plasma after subcutaneous administration, whereas brain penetration is low but with slow elimination. This compound was found active in a transgenic mouse model of familial amyotrophic lateral sclerosis (SOD1-G93A) where it was able to improve grip muscle strength and glutamate uptake from spinal synaptosomal preparations, and prolong survival with a daily dose of 3 mg/kg s.c.

Variations in chemical mimicry by the ectoparasitic mite Varroa jacobsoni according to the developmental stage of the host honey-bee Apis mellifera

The ectoparasitic mite Varroa jacobsoni poses a major threat to the survival of European honey-bee populations. Development of effective control methods is therefore much needed. Study of interspecific chemical communication between the parasite and host is a particularly promising avenue of research. Previous study has shown that the cuticular hydrocarbons of the parasite mite Varroa jacobsoni are qualitatively identical to those of its honey-bee host Apis mellifera (Nation J.L., Sanford M.T., Milne K., 1992. Cuticular hydrocarbons from Varroa jacobsoni. Experimental and Applied Acarology 16, 331-344). The purpose of the present study was to compare the cuticular hydrocarbon patterns of the two species at different stages of bee development. Cuticular components were identified by gas chromatography/mass spectrometry. The proportion of each component was calculated at three stages of bee development (larvae, pupa, emerging bee). The degree of chemical mimicry between the parasite and host was evaluated by multivariate analyses using the resulting proportions for each category of individuals. There were four main findings. The first was that the proportions of some components are different at the larval, pupal and imago stage of bee development. Second, Varroa profiles vary depending on the developmental stage of the host. Third, the cuticular profile of adult mites is more similar to that of the stage of the host than that of later and/or earlier stages except for parasites collected from emerging adult bees. Fourth, the degree of mimicry by Varroa is greater during larval and pupal stages than during the emerging adult bee stages. The role of chemical mimicry - although it is not perfect - in enabling parasites to infest bee colonies by the parasite is discussed.

[Prospective research on the duality between morphological traits and plant competitive capacity: the case of weed species and wheat]

Competitive abilities of plants were interpreted by measuring their morphological traits in interspecific competitive cultivation conditions. Measurements were realised by a comparative approach with interspecific cultivation of fourteen arable weeds growing with a domestic species cultivated at a large scale: the winter wheat (Triticum aestivum var Darius). Results show that arable weeds characterised by an important biomass and allocation of biomass to the stems are responsible for a decrease in wheat biomass, and for the ear, a decrease in height, biomass and number of seeds. These results are discussed in view of predicting competitive abilities of arable weeds with a simple method and for the conservation of arable weeds since some of them are among the most threatened species of the European flora.

Modifications of the cuticular hydrocarbon profile of Apis mellifera worker bees in the presence of the ectoparasitic mite Varroa jacobsoni in brood cells

Varroa jacobsoni is an ectoparasite of Apis mellifera which invades brood cells, on 8-day-old larvae several hours before cell capping. Reproduction of the parasite takes place in the capped brood cells during the nymphose of the bee. Cuticular hydrocarbons of unparasitized bees and of bees parasitized by Varroa jacobsoni were extracted and analysed by gas chromatography (GC) coupled with mass spectrometry (GC-MS). Three developmental stages of worker honey bees were studied: larvae, pupae and emergent adults. The comparison between unparasitized and parasitized hosts was performed with Principal Components Analysis coupled with a multivariate variance analysis. The cuticular hydrocarbon profiles of honey bees were qualitatively similar, for the 3 developmental stages and regardless of the presence of Varroa in the cells. Nevertheless, comparison of the relative proportions of hydrocarbons showed that the cuticular profiles of pupae and emergent adults parasitized by 1 mite and of larvae parasitized by 2 mites were significantly different from the corresponding unparasitized individuals. Such modifications could be regarded (i) as a cause of the multi-infestation in larvae during invasion of brood and (ii) as a consequence of stress and/or removal of proteins contained in the haemolymph of the host during its development.

Mobilization of selenite by Ralstonia metallidurans CH34

Ralstonia metallidurans CH34 (formerly Alcaligenes eutrophus CH34) is a soil bacterium characteristic of metal-contaminated biotopes, as it is able to grow in the presence of a variety of heavy metals. R. metallidurans CH34 is reported now to resist up to 6 mM selenite and to reduce selenite to elemental red selenium as shown by extended X-ray absorption fine-structure analysis. Growth kinetics analysis suggests an adaptation of the cells to the selenite stress during the lag-phase period. Depending on the culture conditions, the medium can be completely depleted of selenite. Selenium accumulates essentially in the cytoplasm as judged from electron microscopy and energy-dispersive X-ray analysis. Elemental selenium, highly insoluble, represents a nontoxic storage form for the bacterium. The ability of R. metallidurans CH34 to reduce large amounts of selenite may be of interest for bioremediation processes targeting selenite-polluted sites.

Effect of age and sex on the production of internal and external hydrocarbons and pheromones in the housefly, Musca domestica

The epicuticular and internal waxes of male and female houseflies were examined by capillary gas chromatography-mass spectrometry at closely timed intervals from emergence until day-6 of adulthood. New components identified included tricosan-10-one, 9,10-epoxyheptacosane, heptacosen-12-one, a series of odd-carbon numbered dienes from C31 to C39, several positional isomers of monoenes including (Z)-9- and 7-pentacosene and a number of methyl- and dimethylalkanes. (Z)-9-tricosene appears in internal lipids prior to appearing on the surface of the insect, suggesting that it is transported in the hemolymph to its site of deposition on the epicuticle. The large increases in the amount of (Z)-9-tricosene in females from day-2 until day-6 is compensated for by a concomitant decrease in (Z)-9-heptacosene. The C23 epoxide and ketone only appear in females after the production of (Z)-9-tricosene is induced, and are only abundant in epicuticular waxes, suggesting they are formed after (Z)-9-tricosene is transported to the cells which are involved in taking them to the surface of the insect. Mathematical analysis indicated that the time shift between internal production and external accumulation in females is more than 24 h. The divergence between male and female lipid production occurs at an early stage, when insects are less than one day old.

Contextual performance prediction for low-level image analysis algorithms

This paper explores a generic approach to predict the output accuracy of an algorithm without running it, by a careful examination of the local context. Such a performance prediction will allow one to qualify the appropriateness of an algorithm to treat images with given properties (contrast, resolution, noise, richness in details, contours or textures, etc.) resulting either from experimental acquisition conditions or from a specific type of scene. We have to answer the following question: a context c being given at any site, what will be the performance? In our experiments, c is described by three contextual variables: Gabor components, entropy and signal noise ratio. As initially proposed in the related work, the prediction function is determined from training using a logistic regression model. This technique is illustrated on aerial infrared images for two types of algorithm: edge detection and displacement estimation.

PMP1 18-38, a yeast plasma membrane protein fragment, binds phosphatidylserine from bilayer mixtures with phosphatidylcholine: a (2)H-NMR study

PMP1 is a 38-residue plasma membrane protein of the yeast Saccharomyces cerevisiae that regulates the activity of the H(+)-ATPase. The cytoplasmic domain conformation results in a specific interfacial distribution of five basic side chains, thought to strongly interact with anionic phospholipids. We have used the PMP1 18-38 fragment to carry out a deuterium nuclear magnetic resonance ((2)H-NMR) study for investigating the interactions between the PMP1 cytoplasmic domain and phosphatidylserines. For this purpose, mixed bilayers of 1-palmitoyl, 2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1-palmitoyl, 2-oleoyl-sn-glycero-3-phosphoserine (POPS) were used as model membranes (POPC/POPS 5:1, m/m). Spectra of headgroup- and chain-deuterated POPC and POPS phospholipids, POPC-d4, POPC-d31, POPS-d3, and POPS-d31, were recorded at different temperatures and for various concentrations of the PMP1 fragment. Data obtained from POPS deuterons revealed the formation of specific peptide-POPS complexes giving rise to a slow exchange between free and bound PS lipids, scarcely observed in solid-state NMR studies of lipid-peptide/protein interactions. The stoichiometry of the complex (8 POPS per peptide) was determined and its significance is discussed. The data obtained with headgroup-deuterated POPC were rationalized with a model that integrates the electrostatic perturbation induced by the cationic peptide on the negatively charged membrane interface, and a "spacer" effect due to the intercalation of POPS/PMP1f complexes between choline headgroups.

Use of plots to define pollen-vegetation relationships in densely forested ecosystems of Tropical Africa

Modern soil samples from South Congo were analyzed for pollen content and compared to forest inventories to define modern pollen-vegetation relationships. A correspondence analysis (CA) was applied independently to botanical and pollen data and a hierarchical cluster analysis to pollen data only. Subsequently, a CA using a presence-absence approach has been made to directly compare the two types of data. Results show that the pollen rain and floristic composition of the sampled sites are not directly linked to altitudinal or precipitation gradients, but clear evidence of variation in relation to hygromorphy and soil type is detected. The forests occurring in swampy environments are well differentiated from the forests developed on well-drained soils by pollen and floristic data. Among forests on well-drained soils, a good distinction can be made between those growing on sandy soils and those growing on ferralitic soils. The comparison between pollen spectra and vegetation shows site-to-site variations in pollen assemblages in relation to the floristic heterogeneity of forests, and it appears that few taxa show a good correlation between plant cover and pollen abundance.

[Phenotypic convergence among pentacrines Endoxocrinus and Diplocrinus related to environmental constraints]

Morphological converging and diverging trends are demonstrated using detailed biometric analyses of the skeleton in pentacrinid populations of the Diplocrininae subfamily living in tropical western Atlantic and in the Pacific Ocean. According to environmental data obtained by in situ submersible observations, water flow characteristics (laminar or with eddies) appear to be the main factor controlling phenotypes through ontogeny. Evidence of convergence between different taxa may be explained by ecological niches with eddies.

Understanding of medico-technical reports

Medical practice produces much in the form of written text. The under-usage of this medical text for research is largely due to difficulties in processing the information. The objective of the Aristotle project is to build an automatic data system that is capable of producing a semantic representation of the text in a canonical form. Understanding the text requires identifying objects mentioned in the text, their properties, and the links between them. The nature of the syntactic process allows the connection, step-by-step, of two lexical units. This connection is immediately controlled by the Interpreter, which assumes the semantic process and queries a knowledge base. The syntactic-semantic Interpreter processes one sentence at a time. The Assembler module links the meaning of the different sentences and structures into the output's shape.

Genotypic variations among isolates ofMarasmius quercophilus, a white-rot fungus isolated from evergreen oak litter

Marasmius quercophilus is a white-rot basidiomycete isolated from evergreen oak litter. This fungus plays an extensive role in litter degradation because of its cellulase, pectinase, and laccase production. Our objective was to investigate the potential genotypic polymorphism of this species using RAPD (random amplified polymorphic DNA) and the amplification and the sequencing of fragments ITS (internal transcribed spacer) from the rRNA repeat. An intraspecies polymorphism was observed for the M. quercophilus isolates studied as suggested by the tree found with RAPD data: seven subgroups were defined. The minimum similarity coefficient observed in these groups was 0.278. The sizes of fragments ITS 1 and ITS 2 were the same for each isolate (ITS 1: 320 bp and ITS 2: 450 bp), and the percentages of nucleotide variation were 1.25 and 1.11%, respectively. Few isolates from the studied population had the same RAPD pattern that would suggest a clonal development in some zones of the site of La Gardiole.Key words: Marasmius quercophilus, intraspecific variability, ITS, RAPD.

The effect of riluzole and mannitol on cerebral oedema after cryogenic injury in the mouse

A cryogenic lesion was produced under halothane anaesthesia in the mouse by placing a cotton swab soaked in liquid nitrogen onto the surface of the cranium. This provoked an oedematous lesion which developed within the hour after the insult and evolved over the following week. Treatment with mannitol at 3 g/kg i.v. caused a significant 22% reduction in oedema 1 h later, when administered immediately after lesion, but not when administered 23-h post lesion. Likewise riluzole (16 mg/kg, i.v.) significantly reduced oedema by 17% when administered immediately after lesion, or 13% (P < 0.05) when administered 23 h after lesion. Repeated doses (2 x 16 mg/kg, i.p.) of riluzole were also able to reduce oedema significantly (24%, P < 0.05) at 24 h post lesion. Riluzole, in four repeated doses of 8 mg/kg i.p. was also able to reduce lesion surface size by 16% (P < 0.05) 48 h after lesion.

Expression and biochemical characterisation of recombinant AceA, a bacterial alpha-mannosyltransferase

Biosynthesis of repeat-unit polysaccharides and N-linked glycans proceeds by sequential transfer of sugars from the appropriate sugar donor to an activated lipid carrier. The transfer of each sugar is catalysed by a specific glycosyltransferase. The molecular basis of the specificity of sugar addition is not yet well understood, mainly because of the difficulty of isolating these proteins. In this study, the aceA gene product expressed by Acetobacter xylinum, which is involved in the biosynthesis of the exopolysaccharide acetan, was overproduced in Escherichia coli and its function was characterised. The aceA ORF was subcloned into the expression vector pET29 in frame with the S.tag epitope. The recombinant protein was identified, and culture conditions were optimised for production of the soluble protein. The results of test reactions showed that AceA is able to transfer one alpha-mannose residue from GDP-mannose to cellobiose-P-P-lipid to produce alpha-mannose-cellobiose-P-P-lipid. AceA was not able to use free cellobiose as a substrate, indicating that the pyrophosphate-lipid moiety is needed for enzymatic activity.

[Obstetric analgesia: peridural analgesia versus combined spinal and peridural analgesia]

OBJECTIVE

To compare the analgesic efficiency, side effects and obstetrical repercussions of epidural analgesia (EP) and combined spinal-epidural analgesia (CSE).

STUDY DESIGN

Prospective, randomized, double or single-blind studies as required, approved by the ethical committee of the institution.

PATIENTS

The study included 80 parturients, in active labour with a singleton in vertex presentation and a cervical dilatation of 3 cm or less, randomly allocated to receive either EP (n = 40) or CSE (n = 40).

METHOD

In the EP group, sufentanil (20 micrograms) and 0.25% bupivacaine (6-8 mL) were injected into the epidural space. In those of the CSE group, sufentanil (10 micrograms) was first injected into the subarachnoid space, followed by an epidural injection of the same agents at the same quantities as for the EP group. Additional analgesia was obtained in both groups by top-ups of 6-8 mL of 0.25% bupivacaine at the request of the patients. Analgesia, course of labour, obstetrical outcome, and neonatal status were assessed. Statistical analysis was performed using Anova, chi 2 analysis, Yates' correction or Fisher's exact test, with a P < 0.05 considered as significant.

RESULTS

Both groups had similar demographic and obstetric data. The onset of analgesia was more rapid in CSE group (8 +/- 11 min vs. 12 +/- 7 min, P < 0.05), however the duration was similar. Technical incidents were more frequent in the CSE group (30% vs. 7%, P < 0.05). The technique of analgesia did not influence the bupivacaine amounts required for its maintenance. The incidence of adverse effects were comparable with the exception of vertigo, which was more frequent in the EP group (57% vs. 28%, P < 0.05). The first stage of labour was increased by 30% in the CSE group (281 +/- 130 min vs. 216 +/- 97 min, P < 0.05), without significant prolongation of labour length. Durations of second stage and expulsion were similar in both groups, despite the administration of a lower dose of bupivacaine in the CSE group (33 +/- 17 mg vs. 46 +/- 12 mg, P < 0.05). The rates of instrumental deliveries and Caesarien sections were comparable. The Apgar scores were satisfactory at 5 min.

CONCLUSION

In the early phase of labour, the CSE technique using intrathecal sufentanil has no significant benefit when compared to the EP technique using bupivacaine and sufentanil. In the CSE group, technical incidents were more frequent and the length of the first stage of labour was increased.

Effect of the laryngeal mask airway on oesophageal pH: influence of the volume and pressure inside the cuff

We studied gastro-oesophageal reflux (GOR) with a face mask and laryngeal mask airway (LMA), and the effects of inflation pressure and volume of the LMA cuff on oesophageal pH, in 60 patients. Patients were managed with either a face mask (group I) or LMA inflated to obtain a seal in the anaesthesia circuit at 7 cm H2O (group II) or 15 cm H2O (group III). A pH-sensitive probe with two electrodes, 10 cm apart, was placed in the oesophagus during anaesthesia and recordings were made continuously until patients awakened. There was a significant difference in the incidence of GOR between the face mask (group I) and the LMA (groups II-III) (P < 0.05) in the lower oesophagus but there was no difference in the mid-oesophagus. No correlation was found between pressure and volume inside the cuff and variations in oesophageal pH. We conclude that LMA use was associated with increased reflux in the low oesophagus but oesophageal pH was not influenced by variations in pressure or volume inside the LMA cuff.

Differential properties of two stably expressed brain-specific glycine transporters

Clonal cell lines stably expressing the glial glycine transporter 1b (GLYT1b) and the neuronal glycine transporter 2 (GLYT2) from rat brain have been generated and used comparatively to examine their kinetics, ion dependence, and electrical properties. Differential sensitivity of the transporters to sarcosine is clearly exhibited by the clonal cell lines. GLYT2 transports glycine with higher apparent affinity than GLYT1b and is not inhibited by any assayed compound, as deduced by glycine transport assays and electrophysiological recordings. A sigmoidal Na+ dependence of the glycine uptake by the stable cell lines is observed, indicating the involvement of more than one Na+ in the transport process. A more cooperative behavior for Na+ of GLYT2 than GLYT1b is suggested. One Cl- is required for GLYT1b and GLYT2 transport cycles, although GLYT1b shows three times higher affinity for this ion than GLYT2. The number of expressed transporters was sufficient to allow electrophysiological recordings of the uptake current in the two stable cell lines. GLYT2 exhibits more voltage dependence in both its glycine-evoked current and its capacitive currents recorded in the absence of substrate.

1H- and 2H-NMR studies of a fragment of PMP1, a regulatory subunit associated with the yeast plasma membrane H(+)-ATPase. Conformational properties and lipid-peptide interactions

PMP1 is a 38-residue polypeptide associated with the yeast plasma membrane H(+)-ATPase, found to regulate the enzyme activity. To investigate the molecular basis of the PMP1 biological function, the conformational properties of a synthetic PMP1 fragment, A18-F38, comprising the predicted C-terminal cytoplasmic domain and a part of the transmembrane anchor have been studied by 1H- and 2H-NMR spectroscopies. High resolution 1H-NMR experiments showed that, in deuterated DPC micelles, the A18-G34 segment adopts a well defined helix conformation. Our data suggest that the whole PMP1 molecule forms a unique helix whose axis might be slightly tilted with respect to the bilayer normal. Protonated DPC, DMPC and DMPS were incorporated in deuterated micelles containing the PMP1 fragment for studying lipid-peptide interactions. Unusually strong and selective intermolecular NOEs between lipid chain and peptide side chain protons, especially those of the unique Trp residue, were observed. Solid state 2H-NMR experiments performed on pure deuterated POPC and mixed deuterated POPC:POPS (5:1) bilayers revealed that the PMP1 fragment specifically interacts with negatively charged PS lipids.

Gene structure, promoter characterization, and basis for alternative mRNA splicing of the human CD58 gene

The 60-kDa lymphocyte function-associated Ag-3 (LFA-3/CD58), a highly glycosylated adhesion molecule that serves as ligand for the T cell-restricted glycoprotein CD2, is encoded by a gene at the human chromosome locus 1p13. We have elucidated the exon-intron organization of the entire human CD58 gene, including approximately 2.5 kilobases (kb) of 5'-flanking DNA. Four overlapping genomic clones, spanning approximately 65 kb, contained the entire approximately 1-kb coding sequence of CD58 and consisted of six separate exons, which varied from 72 to 294 bp in size. At least two different CD58 mRNA precursors can be generated from the human gene as a result of alternative choice of one of the two acceptor splice sites located within exon 5. DNA sequence analysis of about 2.5 kb of 5'-flanking sequence of the CD58 gene indicated the absence of a CAAT box. However, potential binding sites for the transcriptional activators AP-2, GATA, PU.1, and Sp-1 are present. Two consensus TATAA elements, located approximately 2.4 kb upstream of the transcriptional start site, have been identified. The 2.5-kb CD58 promoter sequence displayed functional activity in transient transfection assays in the hepatocellular carcinoma cell line HepG2. Comparing the response of CD58 promoter-driven luciferase plasmids to several cytokines and other agents suggests that the CD58 promoter is regulated by up-regulatory, enhancer-like and down-regulatory, silencer-like elements. Further analysis of this region should allow researchers to gain insight into the molecular mechanisms by which this gene is regulated, e.g., during inflammatory responses.

Differential adsorption of allospecific hydrocarbons by the cuticles of two termite species, Reticulitermes santonensis and R. lucifugus grassei, living in a mixed colony. Passive transfer by contact

When members of the two termite species Reticulitermes santonensis and Reticulitermes lucifugus grassei were placed together, each species acquired some of the allospecific cuticular products. When living individuals of each of these two species were placed together, their cuticular hydrocarbon profiles changed very quickly, since it was within the first two hours of cohabitation that they differed most from those of the corresponding control individuals. After the first two hours, the profiles of the R. santonensis individuals continued to change only very little if at all, whereas 24h later, the process of change continued in the R. lucifugus grassei individuals until their profiles resembled those of the mixed R. santonensis individuals more than their own original profiles. The profiles of the R. l. grassei individuals therefore underwent a greater change than those of the R. santonensis individuals during the period of cohabitation. The fact that similar results were obtained when dead members of these two species were placed together suggests that this difference in the adsorption of allospecific hydrocarbon by the cuticles of the members of the two species cannot be attributable to any behavioural differences, but to differences in physico-chemical composition of the cuticles between the two species.

A Xenopus oocyte beta subunit: evidence for a role in the assembly/expression of voltage-gated calcium channels that is separate from its role as a regulatory subunit

Two closely related beta subunit mRNAs (xo28 and xo32) were identified in Xenopus oocytes by molecular cloning. One or both appear to be expressed as active proteins, because: (i) injection of Xenopus beta antisense oligonucleotides, but not of sense or unrelated oligonucleotides, significantly reduced endogenous oocyte voltage-gated Ca2+ channel (VGCC) currents and obliterated VGCC currents that arise after injection of mammalian alpha1 cRNAs (alpha(1C) and alpha(1E)); (ii) coinjection of a Xenopus beta antisense oligonucleotide and excess rat beta cRNA rescued expression of alpha1 Ca2+ channel currents; and (iii) coinjection of mammalian alpha1 cRNA with cRNA encoding either of the two Xenopus beta subunits facilitated both activation and inactivation of Ca2+ channel currents by voltage, as happens with most mammalian beta subunits. The Xenopus beta subunit cDNAs (beta3xo cDNAs) predict proteins of 484 aa that differ in only 22 aa and resemble most closely the sequence of the mammalian type 3 beta subunit. We propose that "alpha1 alone" channels are in fact tightly associated alpha1beta3xo channels, and that effects of exogenous beta subunits are due to formation of higher-order [alpha1beta]beta(n) complexes with an unknown contribution of beta3xo. It is thus possible that functional mammalian VGCCs, rather than having subunit composition alpha1beta, are [alpha1beta]beta(n) complexes that associate with alpha2delta and, as appropriate, other tissue-specific accessory proteins. In support of this hypothesis, we discovered that the last 277-aa of alpha(1E) have a beta subunit binding domain. This beta binding domain is distinct from the previously known interaction domain located between repeats I and II of calcium channel alpha1 subunits.

[Porphyria cutanea tarda and hepatitis B and C virus infection]

Porphyria cutanea tarda is a metabolic disorder caused by reduced hepatic uroporphyrinogen decarboxylase activity characterized by skin lesions and liver damage. The high frequency of liver histological damage in patients with porphyria cutanea tarda led us to study hepatitis B and C viral infection which has a striking prevalence in southern Europe. We attempt here to expose different pathophysiological hypotheses: is viral hepatitis a triggering factor precipiting latent decreased uroporphyrinogen decarboxylase activity or does it directly induce the enzyme deficiency?

Glycosaminoglycans modulate cell-matrix interactions of human fibroblasts and endothelial cells in vitro

Contact of various cells with extracellular matrix molecules modulates their cellular functions and phenotype. Most investigations have employed dishes coated with purified matrix constituents or plain collagen I lattices omitting the effects of other important matrix components such as proteoglycans. In this study we analyze the effect of purified glycosaminoglycans (GAGs) on human fibroblasts and human umbilical vein endothelial cells (HUVEC) embedded within collagen I/III lattices. HUVEC contracted collagen I/III gels far less efficiently than fibroblasts and addition of heparan sulfate and heparin almost completely inhibited contraction. In collagen gels HUVEC down-regulated collagenase mRNA while increasing collagen I, IV mRNA expression. Addition of heparin and heparan sulfate reversed the collagen IV mRNA induction whereas hyaluronic acid and chondroitin sulfate enhanced fibronectin and collagenase transcripts. Fibroblasts readily contracted collagen gels, and mRNA levels for fibronectin, collagenase and interleukin-6 were stimulated. Gel contraction was mostly unaffected by the different glycosaminoglycans. Fibroblasts responded to the addition of dermatan sulfate, heparan sulfate and heparin with a decrease in fibronectin, collagenase and interleukin-6 mRNA. Binding studies revealed saturable binding sites on fibroblasts and HUVEC for 35S-labelled heparin, demonstrating specificity for heparin and heparan sulfate over other GAGs in competition experiments. This study implies that glycosaminoglycans participate in cell-matrix interactions by effectively modulating the cellular phenotype via high affinity binding sites.

A model for medical knowledge representation application to the analysis of descriptive pathology reports

A new knowledge-representation system is presented, designed for medical knowledge-based applications and in particular for the analysis of descriptive medical reports. Knowledge is represented at two levels. A definitional level uses a concept-type hierarchy, a relation-type hierarchy, and a set of schematic graphs to define the concepts used and the relations between them, as well as different types of cardinality restrictions on these relations. A set of compositional hierarchies using the classic "has-part" relation as well as a new set-inclusion relation allows concept composition to be precisely defined. An assertional level allows the creation and manipulation of empirical data, in the form of graphs using the concepts, relations, and constraints defined at the definition level. The use of cardinality constraints in graph unification is considered in the context of descriptive medical discourse analysis.

CCK-JMV-180 acts as an antagonist of the CCKA receptor in the human IMR-32 neuroblastoma cell line

[125I]Cholecystokinin-8-S (CCK-8-S) bound to a single class of saturable binding sites on the human neuroblastoma cell line IMR-32 (KD = 4 +/- 1.5 nM, Bmax = 10,500 +/- 3,500 sites/cell (n = 6)). These binding sites were of the CCKA type, as demonstrated by the differential inhibition of the binding of [125I]CCK-8-S and CCK-8-S-induced 45Ca2+ efflux by the specific CCKA antagonist SR 27897 and the specific CCKB antagonist PD 134,308. CCK-JMV-180, an analogue of CCK-8-S which has been shown to activate 45Ca2+ efflux in rat cells in a manner similar to CCK-8-S, acted as a potent antagonist of CCK-8-S-induced 45Ca2+ efflux (IC50 = 50 nM) and inhibited [125I]CCK-8-S binding to IMR-32 cells (IC50 = 1.7 nM). These results show that, unlike its CCK-like effect in various animal systems, CCK-JMC-180 acts as an antagonist of CCKA receptors in the human neuroblastoma cell line IMR-32.

Representation of medical concepts of the thyroid gland by physicians in anatomy and pathology

An experimental study in cognitive psychology is described, concerning the categorization of medical concepts into specific classes, expressed by physicians specialized in anatomic pathology consultations of the thyroid gland. This study belongs to a medical computer science project, called ARISTOTLE, concerning Natural Language Processing of specialized medical reports in anatomic pathology of the thyroid gland. This research has been done for two reasons; first, to specify the characteristics of human expert categorization in an area of medical knowledge and, secondly, to validate the hierarchical organization of a prototype declarative knowledge base. In this experiment, physicians were asked to categorize 121 concepts into 10 proposed classes. These classes and concepts belong to expert knowledge represented in a conceptual graph that was constructed before the experiment. Results show variable semantic distances between concepts of a same class, and dynamic variations of these distances due to contextual representation.

Persistent reduction of complement receptor 3 alpha-chain expressing mononuclear blood cells and transient inhibitory serum factors in Whipple's disease

Several small studies have indicated an impaired cell mediated immune response as a possible cause for the delayed elimination of the bacteria in Whipple's disease. A specific defect, however, has not been defined. We examined the expression of cell surface molecules and mitogenic responses of peripheral blood mononuclear cells in 27 patients with Whipple's disease at different disease stages by indirect immunofluorescence and by measurement of [3H]thymidine incorporation, respectively. E-rosette formation and cutaneous reaction to seven recall antigens were determined. Matched healthy donors served as controls. We found a significantly reduced number of cells expressing the complement receptor 3 alpha-chain (= CD11b) in all patients. In florid disease, the number of activated cells (in particular CD58 positive cells) was increased and CD4/CD8 ratios were diminished. Proliferation to phytohemagglutinin and to sheep red blood cells was reduced at all stages of the disease. Serum of control persons reversed this decreased responsiveness especially in patients with active disease. Skin reaction was hypoergic in all patients. Determination of CD58 positive cells increased in patients with active disease may be useful to define the activity of the disease and the duration necessary for treatment. Transient inhibiting serum activities may impair the CD2/CD58 interaction. The reduction of cells expressing CD11b, the decreased proliferation, and the cutaneous hypoergy indicate a persisting defect of cell mediated immunity in vivo and in vitro. These defects may contribute to the impaired ability of patients with Whipple's disease to eliminate bacteria.

Neuroprotective effects of colchicine in the gerbil model of cerebral ischaemia

The tropolonic alkaloid colchicine significantly reduces the behavioural, electroencephalographic and histological damage seen after a 6-min occlusion of the two common carotid arteries of the Mongolian gerbil if the compound is administered at 2 or 4 mg/kg i.p. immediately upon reperfusion. A 45% increase in high-frequency ECoG activity and significant reduction of 80% in the hypermotility of the gerbils, with 63% less faults in a passive avoidance paradigm, were observed in conjunction with considerable protection of the hippocampus, after a single dose of 4 mg/kg colchicine. No adverse effects of colchicine treatment on animal movement and body weight were observable. Colchicine's possible mode of action, via inhibition of cellular transport systems, is discussed.

[Sclerodermiform skin changes in Borrelia burgdorferi infection. Diagnostic use of polymerase chain reaction]

We report on a 61-year-old patient with sclerodermiform skin lesions of the extremities and polyneuropathy. Borrelia (B.) burgdorferi DNA was detected in lesional skin by the polymerase chain reaction. Serological testing revealed IgG antibodies to B. burgdorferi. Histology revealed an inflammatory stage of a sclerotic reaction in the lesional skin. The admixture of plasma cells and the perineural distribution of the cellular infiltrate was suggestive for a borrelia infection. Immunohistochemical staining for the B. burgdorferi flagellin (41 kDa) revealed a positive staining reaction in the epidermis of lesional skin. The improvement of both the dermatological and the neurological symptoms upon antibiotic treatment with ceftriaxone was taken as further support for the diagnosis of a. B. burgdorferi infection.

Fragmentation of phospholipid bilayers by myelin basic protein

Human myelin basic protein (MBP) is shown to disrupt multilamellar phosphatidylcholine bilayers into small lipoprotein particles in a manner similar to the cytolytic peptide melittin (Dufourc, E. J., Smith, I. C. P., & Dufourcq, J. (1986) Biochemistry 25, 6448-6455). This bilayer fragmentation, as monitored by 31P nuclear magnetic resonance, is temperature-dependent and completely inhibited by the presence of small amounts of negatively charged phosphatidylserine. The stabilizing property of phosphatidylserine is lost with the neutralization of its negative charges upon membrane binding of cationic species such as calcium ions. No MBP-induced fragmentation is observed with bilayers of negative or zwitterionic lipid mixtures which mimic the myelin lipid composition. The membrane fragmentation observed in vitro in the presence of MBP could play a role in vivo in demyelinating diseases.

A soluble form of the adhesion receptor CD58 (LFA-3) is present in human body fluids

The human adhesion receptor CD58 (LFA-3) is expressed on most human cell types. Here we report on a soluble form of CD58 (sCD58) in human serum, human urine, and culture supernatants of several cell lines. sCD58 partially purified from human serum, from supernatant of the Hodgkin cell line L428, and purified sCD58 from human urine were found to have a molecular mass of 40-70 kDa under denaturating conditions (sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting). However, gel filtration of sCD58 purified from human urine gave a molecular mass of 118-166 kDa, suggesting a noncovalent homotrimer conformation or its association with other molecules. Using an enzyme-linked immunosorbent assay specific for CD58 we found that sera from patients suffering from different forms of hepatitis contained elevated sCD58 levels (n = 108). Accordingly, there was a fivefold increase of supernatant sCD58 when the hepatocellular carcinoma cell line Hep G2 was incubated with 25 ng/ml recombinant tumor necrosis factor-alpha in vitro. In contrast, sCD58 serum levels of 337 additional patients suffering from various other immunological disorders were not found to be raised. At high concentrations sCD58 binds to CD2-positive cells and inhibits rosette formation of human T cells to human erythrocytes. Thus, local release of large quantities of naturally occurring sCD58 may interfere with intercellular adhesion in vivo.

RP 59037 and RP 60503: anxiolytic cyclopyrrolone derivatives with low sedative potential. interaction with the gamma-aminobutyric acidA/benzodiazepine receptor complex and behavioral effects in the rodent

This study describes the pharmacological properties of two novel cyclopyrrolone derivatives, RP 59037 [2-(7-chloro-2-naphthyridin-1,8-yl)-3-(5- methyl-2-oxohexyl)isoindolin-1-one] and RP 60503 [2-(7-chloro-2-naphthyridin-1,8-yl)isoindolin-1-yl-4- acetamidobutyrate], in the rodent. These compounds possess high affinity for the benzodiazepine binding site on the gamma-aminobutyric acidA receptor in rat cerebrocortical membranes with Ki values of 0.98 nM (RP 59037) and 1.16 nM (RP 60503). Neither compound discriminates between the putative benzodiazepine BZ1 and BZ2 binding site subtypes present in the rat cerebellum and hippocampus, respectively. Both compounds protect mice against pentylenetetrazole-induced seizures with ID50 values of 0.21 mg.kg-1 p.o. (RP 59037) and 5.96 mg.kg-1 p.o. (RP 60503). The two compounds displayed a restricted anticonvulsant profile compared to diazepam and, in this respect, resembled the pyrazoloquinoline partial agonist, CGS 9896. RP 59037 and RP 60503 were active in two rat models predictive of anxiolytic drug action, a modified Geller-Seifter conflict paradigm (minimal effective dose, 0.33 mg.kg-1 p.o. for RP 59037 and 5 mg.kg-1 p.o. for RP 60503) and the elevated plus maze (minimal effective dose, 0.33 mg.kg-1 p.o. for RP 59037 and 5 mg.kg-1 p.o. for RP 60503). Only very low activities were observed in tests of sedative or myorelaxant effects (ED50 > 50 mg.kg-1 p.o.). It is concluded that the two cyclopyrrolones possess a dissociated behavioral profile, displaying potent anxiolytic and anticonvulsant properties with little or no sedative or myorelaxant effects. Although both compounds appear to be partial agonists at their allosteric recognition site on the gamma-aminobutyric acidA receptor, RP 60503 seems to be more dissociated than RP 59037, which would be compatible with it having lower intrinsic activity. This difference is reflected in a higher receptor occupancy requirement for activity, and a smaller modulatory effect on the binding of t-[35S]butylbicyclophosphothionate.

Structural and functional epitopes of the human adhesion receptor CD58 (LFA-3)

CD58 (LFA-3), a heavily glycosylated protein of 40-70 kDa, is expressed on a broad range of hematopoietic and non-hematopoietic cells. It serves as a physiological ligand of the CD2 receptor, present on T cells and natural killer cells, and plays, thus, an important role in lymphocyte adhesion and T cell activation through CD2. Whereas several epitopes and their respective function are known for CD2, a similarly detailed characterization of CD58 is still lacking. We raised a panel of novel murine monoclonal antibodies (mAb) against recombinant human CD58 and describe here the identification of six structurally and/or functionally distinct epitopes on the CD58 molecule. All epitopes were found to be present in equal numbers on a wide range of CD58+ cells, none of them being differentially up-regulated following cell activation or malignant transformation. Two of these epitopes represent functionally relevant sites, involved in binding of CD58 to CD2 and T cell activation via CD2. One further epitope appears to be selectively involved in CD58-mediated activation, whereas the other three displayed no functional effects. The new mAb allow for the first time the detection of CD58 in enzyme-linked immunosorbent assays and immunofluorescence while bound to its receptor CD2 in human serum or on freshly isolated blood cells. Finally, one mAb was found to specifically cross-react with T11TS, the equivalent of CD58 in sheep.

A simple vacuum transfer device for nucleic acids

We present a new vacuum device intended for transferring nucleic acids from agarose gels onto hybridization membranes. The apparatus is drawn so that plastic sheets serve as substitutes for the elaborate, but cumbersome and unnecessary, locking systems mounted on all the commercial blotters. This substitution results in (1) a much more easy and rapid set-up of the transfer and (2) a very simple framework allowing the possibility of low-cost manufacturing.

Neuroprotective actions of riluzole in rodent models of global and focal cerebral ischaemia

Riluzole (2 amino 6-trifluoromethoxybenzothiazole), when administered at 4 and 8 mg/kg i.p., 0.5, 4.5, 24 and 28 h after the initiation of ischaemia, significantly reduced the prevalence of slow wave, and increased the proportion of higher frequency activity seen in the quantified electrocorticogram (ECoG), during the weeks that followed a 6 min bilateral occlusion of the common carotid arteries in the Mongolian gerbil. In focal ischaemia, provoked in Fischer rats following the occlusion of the middle cerebral artery, administration of riluzole (8 mg/kg) at 30 min and 24.5 h post occlusion significantly reduced the volume of infarcted cortex. These activities of riluzole could be related to its inhibition of sodium channel activity, which in turn inhibits glutamate release.

Influence of beta-blockade on circulating plasma levels of 3-methoxy-4-hydroxy phenylethylene glycol (MHPG) during exercise in moderate hypertension

1. The effect of exercise testing and beta-blockade on plasma norepinephrine (PNE), and secretion of its metabolite 3-methoxy-4-hydroxyphenylethylene glycol (MHPG), was assessed in 28 mild-to-moderate hypertensives before and after the administration of dilevalol, a new beta-blocker with beta 2-agonism. 2. This double blind, placebo-controlled study consisted of two successive submaximal exercise tests before and after the administration of a single oral dose of dilevalol (200 mg, 400 mg or 600 mg). Plasma norepinephrine levels were determined at rest, at 100 watts step of exercise and at maximal effort (Emax). 3. During the control test, mean PNE levels increased from 1.73 +/- 0.52 nmol/L (resting value) to 8.01 +/- 4.01 nmol/L at Emax (P less than 0.01) as MHPG levels increased from 11.18 +/- 1.33 nmol/L (rest) to 17.50 +/- 1.15 nmol/L (Emax, P less than 0.01). After dilevalol, PNE increased significantly as compared to controls (P less than 0.05), from 2.32 +/- 0.99 to 12.42 +/- 5.97 nmol/L (P less than 0.01). PNE and MHPG levels were correlated, both at rest and during exercise. PNE levels after beta-blockade were linearly related to the dose of beta-blocker administered. MHPG levels were unaltered by the administration of dilevalol, both before and after exercise. 4. The increase in MHPG that occurs during bicycle exercise is largely generated from an increase in central nervous system noradrenergic activity. While dilevalol increases the peripheral sympathetic nervous system, both at rest and during exercise (which is reflected by increases in PNE levels) the drug does not alter resting central nervous system noradrenergic activity nor amplify the increase in central noradrenergic activity that occurs during exercise.

Natural inhibitors of T-cell activation in Hodgkin's disease

Secondary immunodeficiency is frequently observed in Hodgkin's disease (HD) and is due in part to impaired T-cell function. Using monoclonal antibodies that bind to triggering molecules of human T lymphocytes (CD3/Ti antigen receptor; CD2 E-rosette receptor) and exert functional effects on T-cell activation, we have investigated in vitro immune responses of circulating lymphocytes from patients with HD in progression (n = 9) and in remission (n = 14). In patients with progressive HD, a severe dysfunction of the alternative CD2-mediated T-cell activation pathway was detected (49.3 +/- 14.2 v 9.4 +/- 5.1 cpm x 10(-3), in controls, P less than .01; n = 9) that parallels the reduced capacity of T lymphocytes to form rosettes with sheep red blood cells. Diminished alternative pathway activation in HD is not only due to a defect at the cellular level but also due to soluble mediators in the patients' plasma. Plasma from patients in progression markedly reduces CD2 mediated activation (P less than .01). These activities interfere, at least in part, with CD2/CD58 interactions and, therefore, reduce T-lymphocyte triggering through this amplifier mechanism.

GTP hydrolysis mechanisms in ras p21 and in the ras-GAP complex studied by fluorescence measurements on tryptophan mutants

We have substituted leucine 56 or tyrosine 64 of p21 ras with a tryptophan. The intrinsic fluorescence of this tryptophan was used as an internal conformational probe for time-resolved biochemical studies of the ras protein. The slow intrinsic GTPase, GDP/GTP exchange induced by the SDC25 "exchange factor", and the fast GTP hydrolysis induced by GAP were studied. Tryptophan fluorescence of mutated ras is very sensitive to magnesium binding, GDP/GTP exchange, and GTP hydrolysis (changes in tyrosine fluorescence of wild-type ras are also observed but with a lower sensitivity). Nucleotide affinities, exchange kinetics, and intrinsic GTPase rates of the mutated ras could be measured by this method and were found to be close to those of wild-type ras. The SDC25 gene product enhances GDP/GTP exchange in both mutants. In both mutants, a slow fluorescence change follows the binding of GTP gamma S; its kinetics are close to those of the intrinsic GTPase, suggesting that a slow conformational change precedes the GTPase and is the rate-limiting step, as proposed by Neal et al. (1990) (Proc. Natl. Acad. Sci. U.S.A. 87, 3562-3565). GAP interacts with both mutant ras proteins and accelerates the GTPase of (L56W)ras but not that of (Y64W)ras, suggesting a role for tyrosine 64 in GAP-induced GTP hydrolysis. However, GAP does not accelerate the slow conformational change following GTP gamma S binding in either of the mutated ras proteins. This suggests that the fast GAP-induced catalysis of GTP hydrolysis that is observed with (L56W)ras bypasses the slow conformational change associated with the intrinsic GTPase and therefore might proceed by a different mechanism.

Calcium binding by phosphatidylserine headgroups. Deuterium NMR study

The binding of calcium to headgroup deuterated 1-palmitoyl, 2-oleoyl-sn-glycero-3-phosphoserine (POPS) was investigated by using deuterium magnetic resonance in pure POPS membranes and in mixed 1-palmitoyl, 2-oleoyl-sn-glycero-3-phosphocholine (POPC)/POPS 5:1 (m:m) bilayers. Addition of CaCl2 to pure POPS bilayers led to two component spectra attributed, respectively, to liquid-crystallin POPS (less than 15 kHz) and POPS molecules in the calcium-induced dehydrated phase (cochleate) (approximately 120 kHz). The liquid-crystalline component has nearly disappeared at a Ca2+ to POPS ratio of 0.5, indicating that, under such conditions, most of the POPS molecules are in the precipitated cochleate phase. After dilution of the POPS molecules in zwitterionic POPC membranes (POPC/POPS 5:1 m:m), single component spectra characteristic of POPS in the liquid-crystalline state were observed in the presence of Molar concentrations of calcium ions (Ca2+ to POPS ratio greater than 50), showing that the amount of dehydrated cochleate PS-Ca2+ phase, if any, was low (less than 5%) under such conditions. Deuterium NMR data obtained in the 15-50 degrees C temperature range with the mixed PC/PS membranes, either in the absence or the presence of Ca2+ ions, indicate that the serine headgroup undergoes a temperature-induced conformational change, independent of the presence of Ca2+. This is discussed in relation to other headgroup perturbations such as that observed upon change of the membrane surface charge density.