Fate of biomedical research protocols and publication bias in France: retrospective cohort study

Objectives To describe the fate of protocols approved by the French research ethics committees, a national system created by the French 1988 Huriet-Sérusclat Act; to assess publication bias at a national level.Design Retrospective cohort study.Setting Representative sample of 25/48 French research ethics committees in 1994.Protocols 649 research protocols approved by committees, with follow-up information.Main outcome measures Protocols'' initial characteristics (design, study size, investigator) abstracted from committees'' archives; follow-up information (rates of initiation, completion, and publication) obtained from mailed questionnaire to principal investigators.Results Completed questionnaires were available for 649/976 (69%) protocols. Of these, 581 (90%) studies were initiated, 501/581 (86%) were completed, and 190/501 (38%) were published. Studies with confirmatory results were more likely to be published as scientific papers than were studies with inconclusive results (adjusted odds ratio 4.59, 95% confidence interval 2.21 to 9.54). Moreover, studies with confirmatory results were published more quickly than studies with inconclusive results (hazard ratio 2.48, 1.36 to 4.55).Conclusion At a national level, too many research studies are not completed, and among those completed too many are not published. We suggest capitalising on research ethics committees to register and follow all authorised research on human participants on a systematic and prospective basis.     

Chromatographic and immunological evidence that chloroplastic and cytosolic pea (Pisum sativum L.) NADP-isocitrate dehydrogenases are distinct isoenzymes

Two NADP-isocitrate dehydrogenase isoenzymes designated as NADP-IDH₁ and NADP-IDH₂ (EC 1.1.1.42) were identified in pea (Pisum sativum) leaf extracts by diethylaminoethylcellulose chromatography. The predominant form was found to be NADP-IDH₁ while NADP-IDH₂ represented only about 4% of the total leaf enzyme activity. These enzymes share few common epitopes as NADP-IDH₂ was poorly recognized by the specific polyclonal antibodies raised against NADP-IDH₁, and as a consequence NADP-IDH₂ does not result from a post-translational modification of NADP-IDH₁. Subcellular fractionation and isolation of chloroplasts through a Percoll gradient, followed by the identification of the associated enzymes, showed that NADP-IDH₁ is restricted to the cytosol and NADP-IDH₂ to the chloroplasts. Compared with the cytosolic isoenzyme, NADP-IDH₂ was more thermolabile and exhibited a lower optimum pH. The data reported in this paper constitute the first report that the chloroplastic NADP-IDH and the cytosolic NADP-IDH are two distinct isoenzymes. The possible functions of the two isoenzymes are discussed.Abbreviations BSA bovine serum albumin - DEAE diethylaminoethyl - NADP-IDH NADP-isocitrate dehydrogenase - NADP-IDH₁ cytosolic NADP-IDH - NADP-IDH₂ chloroplastic NADP-IDH     

Evaluation of the relative amount of specific gaba-benzodiazepine receptor mrna after injection of total poly(A+)-rna into xenopus oocytes

GABA-benzodiazepine receptor-chloride channel complexes have been detected by electrophysiological recording in Xenopus oocytes previously injected with messenger RNA extracted either from optic lobes of chick embryos or from adult rat hippocampi. The ability of the oocyte to correctly translate exogenous messengers was used to develop a routine method which could allow a quantitative evaluation of specific mRNA coding for GABA-benzodiazepine receptor proteins following an injection of a fixed amount of total poly(A+)-RNA. The conditions of the validation of this method have been determined.     

New chromosome 21 DNA markers isolated by pulsed field gel electrophoresis from an ETS2-containing Down syndrome chromosomal region

To generate new chromosome 21 markers in a region that is critical for the pathogenesis of Down syndrome (D21S55-MX1), we used pulsed field gel electrophoresis (PFGE) to isolate a 600-kb NruI DNA fragment from the WA17 hybrid cell line, which has retained chromosome 21 as the only human material. This fragment, which contains the oncogene ETS2, was used to construct a partial genomic library. Among the 14 unique sequences that were isolated, 3 were polymorphic markers and contained sequences that are conserved in mammals. Five of these markers mapped on the ETS2-containing NruI fragment and allowed us to define an 800-kb high-resolution PFGE map.     

Protein Synthesis Linked to Respiration and Phosphorylation in Intact Euglena Mitochondria

Highly purified condensed mitochondria obtained from bleachedmutant. W₁₀BSmL of Euglena gracilis Klebs var bacillaris Coriincorporate [³⁵S]methionine into protein when fortified withmalate, ADP, Mg²⁺, phosphate and a sucrose osmoticum. Twentyto twenty-five polypeptide bands were found to be labeled inorganello when the labeled protein was subjected to sodium dodecylsulfatepolyacrylamide gel electrophoresis. Methionine incorporation,but not respiration or oxidative phosphorylation, was blockedby chloramphenicol and other 70S ribosomal translation inhibitorsbut cycloheximide and ribonuclease were without effect. Inhibitorsof electron transport and uncouplers of oxidative phosphorylationwere excellent inhibitors of protein synthesis. Thus, thesemitochondrial preparations carry out protein synthesis in organellothat is linked to respiration and oxidative phosphorylation. ¹Present address: VA Hospital Outpatient Clinic, 17 Court St.,Boston, MA 02115, U.S.A. ²Present address: Laboratories de Microbiologia e Inmunologia,Universidad Catolica de Chile, Casilla 114-D, Santiago, Chile. ³Present address: Botany Department, University of Massachusetts,Amherst, MA 01003, U.S.A. (Received June 17, 1985; Accepted October 28, 1985)     

Increase of translational fidelity blocks sporulation in the fungus Podospora anserina

Summary AS7-1 and AS7-2 are antisuppressor mutations reducing the miscoding capacity of ribosomes. Strains carrying and AS7 mutation do not sporulate. We have investigated whether the sporulation deficiency is due to the decrease of translational ambiguity. Two major findings argue in favour of this assumption. First, a significant sporulation level is restored in the presence of paromomycin. Second, three mutations which restore the sporulation of AS7-2 increase the ribosomal misreading in vitro. They define two new loci for ribosomal suppressors, su11 and su12. The two ribosomal proteins altered by su11-1 and su12-1 have been identified by electrophoresis. The results are discussed in the context of a more general hypothesis proposed by Picard-Bennoun (1982).     

Evolution of a Vκ gene family

To examine the evolution of multigene families we have selected as an example an immunoglobulin light chain variable region subgroup (V24) which has been extensively characterized in inbred mice (Mus musculus domesticus). Homologous genes have been isolated and sequenced from Mus pahari, a genetically and geographically isolated species believed to be the oldest living representative of the genus. Southern blot analysis using probes corresponding to individual genes in this subgroup reveals changes in the overall size of the family occurring at the level of individual genes but not at the level of the entire family. Nucleotide sequence analysis indicates an absence of regulatory sequences such as the CAT and TATA boxes 5 to the coding region, but a decanucleotide sequence involved in light chain expression is highly conserved. Within coding regions highly complex patterns of variation are seen which appear to reflect quite different selective pressures on various subregions of the coding sequence. Complementarity determining regions (CDR) are conserved to different extents, with the first CDR region in all family members being among the most conserved segments of the molecule. Conservation is similarly variable among framework segments, indicating complex and variable evolutionary pressures not only at the level of individual genes or their products but also at subregions within homologous molecules.     

L'os cellulaire d'un Poisson Téléostéen ≪Anguilla anguilla L.≫

Résumé Le squelette vertébral de l'Anguille est formé d'os cellulaire: lamellaire compact ou spongieux, suivant les différentes parties de la vertèbre. Nous avons pu y mettre en évidence, chez des animaux physiologiquement normaux, les trois catégories de cellules caractéristiques de l'os des vertébrés supérieurs: ostéoblastes, osteocytes, ostéoclastes. Elles ont les mêmes fonctions que chez ces derniers, les ostéoblastes procèdent à l'élaboration du tissu osseux, alors que les ostéoclastes le détruisent; à cette résorption ostéoclastique s'ajoute une lyse périostéocytaire ou résorption périlacunaire. Les osteocytes, dans ce tissu, nous paraissent être des éléments actifs; néanmoins, leur nombre (par unité de surface) est très inférieur à celui trouvé chez les Mammifères. Le remaniement osseux résultant du jeu de l'apposition et de la résorption est important et comparable à celui existant chez l'Homme.L'os de l'Anguille est, à de nombreux points de vue, très voisin de celui des Mammifères; les Poissons n'ont pas de parathyroïdes en tant que telles mais ils sont pourvus d'autres glandes vraisemblablement impliquées dans la régulation phosphocalcique: corps ultimobranchial et corpuscules de Stannius. Notre but sera donc d'essayer de déterminer comment est réglé le métabolisme de l'os cellulaire des Téléostéens.

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Histologic study on teleost cellular bone I.

Summary The vertebral skeleton of the eel consists of cellular bone, either lamellar or spongy, depending on different parts of the vertebra. In this osseous tissue we have found, in physiologically normal animals, three categories of caracteristic cells of the bone of higher vertebrates: osteoblasts, osteocytes, osteoclasts. They have the same functions as in higher vertebrates, osteoblasts form the bone while the osteoclasts which are to be found in Howship's lacunae destroy it. In addition, a perilacunar type of bone resorption or osteocytic osteolysis can be observed. In this bone, osteocytes seem to be active cells, but the concentration of osteocytes is decidedly lower than that to be found in Mammals.The osseous remodeling produced by apposition and resorption is of the same importance as in human bone. The bone of the eel, in many ways, closely resembles that of mammals. Teleost fish do not have parathyroid glands, but their phosphocalcic regulation seems to be facilitated by the action of two endocrine glands: Ultimobranchial body and the corpuscles of Stannius.The regulation of the cellular bone metabolism of Teleostean fishes is discussed.

Nous remercions Monsieur le Professeur Baud qui nous accueille dans son laboratoire à Genève et qui nous prodigue ses conseils.     

Germline genomic structure of the B10.A mouseTcra-V2 gene subfamily

 The number of mouse Tcra-V gene segments varies from one individual to another and is estimated to be about 100. Southern blot analysis revealed that most of the Tcra-V are organized in clusters composed of copies of Tcra-V belonging to different subfamilies. We analyzed in detail a Tcra-V subfamily and looked for new Tcra-V in order to improve the knowledge of the mouse Tcra locus organization. A series of genomic clones derived from the B10.A mouse strain enclosing these clusters was used to determined the structure of all the Tcra-V2. We were able to identify ten Tcra-V2. This study showed that the Tcra-V2 can be organized into three structural subgroups. The distribution of the genes along the Tcra locus, plus their structural organization, indicates that successive duplications occurred during the processes of expansion and contraction of the Tcra-V gene subfamilies. Several Tcra-V2 are also identical, indicating recent duplications. The most divergent Tcra-V2 differ by 7.4% nucleotides, leading to 5.2% differences in amino acid contents. Received: 8 August 1995 / Revised: 24 April 1996     

Characterization of In Vivo Reporter Systems for Gene Expression and Biosensor Applications Based on luxAB Luciferase Genes

Advances in genetic engineering methods have allowed the development of an increasing number of practical and scientific applications for bioluminescence with lux genes cloned from a variety of organisms. Bioluminescence derived from the shortened lux operon (luxAB genes) is a complex process, and applications seem to be proliferating in advance of an understanding of the underlying biochemical processes. In this report, we describe a two-phase kinetic behavior of the light emission which must be properly taken into account in any quantitative measurements of the bioluminescence signal. By using strains of Escherichia coli and Caulobacter crescentus, this behavior was characterized and interpreted in terms of the biochemistry underlying the bacterial luciferase mechanism. We show that the intensity profile of each of the two phases of the luminescence signal is responsive (and exhibits different sensitivities) to the concentration of added decanal and other components of the assay mix, as well as to the order of mixing and incubation times. This study illustrates the importance of appropriate protocol design, and specific recommendations for using the luxAB system as a molecular reporter are presented, along with versatile assay protocols that yield meaningful and reproducible signals.