Late ventricular fibrillation following successful resuscitation from postinfarction cardiogenic shock with intraaortic balloon pumping

Early ventricular fibrillation occurs in approximately 5% of patients admitted for acute myocardial infarction. Although late ventricular fibrillation (> 48 hours postinfarction) may occur in stable patients, it occurs more commonly when severe left ventricular power failure is present. We have encountered late ventricular fibrillation in three of 42 (7%) patients treated with intraaortic balloon pumping (IABP) for profound cardiogenic shock secondary to myocardial infarction. These patients progressed to our hemodynamic Class A prior to weaning, and were thought to be stable prior to IABP removal. They were the only ones who expired after achieving Class A status. The episodes of late ventricular fibrillation occurred after the patients had been successfully weaned from IABP and were free of arrhythmias. This experience suggests that prolonged antiarrhythmic therapy may be indicated for postinfarction patients who have had ventricular dysrhythmias during IABP support.     

Effects of plant diversity and time of colonization on an herbivore-plant interaction

Summary Experimental field plantings showed that plant diversity strongly affected the population dynamics of a specialist herbivore, the striped cucumber beetle, Acalymma vittata (Fab.) (Coleoptera: Chrysomelidae). Population densities over time were characterized by two peaks in numbers (from colonization and reproduction, respectively) and were consistently higher in cucumber monocultures (Cucumis sativus L.) than in polycultures of cucumbers, corn (Zea mays L.), and broccoli (Brassica oleracea L.). Greater abundances in monocultures appear to result from two factors: (1) per individual reproductive rates were greater in monocultures than in polycultures, and (2) mark-recapture studies confirmed that beetles stay in monocultures for a longer period of time than in polycultures. Differences in predation did not appear to contribute to the overall differences in herbivore abundances.The primary impact of A. vittata on its host plant, C. sativus, is the dissemination of bacterial wilt disease, Erwinia tracheiphila (E.F.Sm.). Greater numbers of beetles led to greater plant mortality in monocultures. It is suggested that factors other than numbers of beetles (e.g., shading, allelopathy, microclimate) are more important in influencing plant reproduction, since cucumber plants in monocultures had greater yields than did plants grown in polycultures. However, time of beetle colonization strongly affected plant parameters, indicating that the length of time during which herbivores are interacting with plants is of critical importance to plant survivorship, and thus reproduction.     

Localisation régionale des gènes humains IDHS,MDHS, PGK, α-GAL,G6PD par l'hybridation cellulaire interspécifique

Summary 22 independent man-hamster (HGPRT^–) hybrids using male human cells with balanced reciprocal translocation t(X;2)(p22;q32) were analysed for human genes localized on chromosome 2 (IDH_S, MDH_S), on chromosome X (PGK, GAL, G6PD) and for the different chromosomes in relation with the balanced reciprocal translocation (chr.2, chr.2q^–, chr.Xp⁺).The following results were obtained:The chromosomes 2 and 2q^– are absent in the 22 hybrids.In 9 hybrids, the absence of MDH_S in spite of the presence of the chromosome Xp⁺ indicates that the gene for MDH_S is not localized on this chromosome (or that the gene for MDH_S is not on the segment 2q32-2qter translocated on X).In 14 hybrids, the three markers of X (PGK, GAL, G6PD) and IDH_S are expressed in the presence of the chromosome Xp⁺. This result indicates that the genes for these markers are on Xp⁺ or that the genes PGK, GAL, G6PD are on X without the Xp22-Xter segment, translocated on the chr.2, and that the gene for IDH_S is on the 2q32-2qter segment translocated on X.In 8 hybrids, in the absence of the intact chromosome Xp⁺, the higher percentage of the presence of G6PD (7 hybrids) and the lower percentage of the presence of IDH_S (3 hybrids) are explained by the fact that these hybrids selected in HAT medium had to retain a segment of Xp⁺ bearing the human gene HGPRT. G6PD appeared very close to HGPRT and IDH_S very distant from HGPRT.The study of the different correlations between the presence and the absence of these four markers on Xp⁺ in the different hybrids indicates the following order on the chromosome Xp⁺ from p to q: IDH_s — PGK — GAL — G6PD.

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Groupe INSERM: Directeur J. Frézal

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Groupe CNRS, ER, 149: Directeur J. de Grouchy     

Alcaloides du Strychnos tchibangensis

The structure of a new bisindole alkaloid has been elucidated by chemical correlation and analysis of ¹³C NMR spectra.     

2-Heptanone Production by Spores of Penicillium roquefortii in a Water-Organic Solvent Two-Phase System

The production of 2-heptanone from octanoic acid may be performed by free and entrapped spores of Penicillium roquefortii in a water-organic solvent two phase system.

An industrial, isoparafflnic solvent, i.e. Hydrosol IP 230 O.S., which may be considered as tetradecane, is well suited for the process. Activities nearly double those achieved with aqueous systems are observed using an initial fatty acid content in the organic layer close to 100 mM and a ratio of the volume of the organic phase to the total volume of the medium of 0.88. The presence of the solvent allows a better recovery of the metabolite by lowering its activity coefficient.

Fed-batch experiments performed in an aerated, stirred reactor show that the bioconversion may proceed in the two-phase system for at least 300 h. These conditions allow conversion of 750 mM (108 g · 1^-1) fatty acid, and production of 600 mM (68.5 g · 1^-1) 2-heptanone.     

The activation process of Arabidopsis thaliana A1 gene encoding the translation elongation factor EF-1α is conserved among angiosperms

In Arabidopsis thaliana, the activation process of the A1 EF-1 gene depends on several elements. Using the GUS reporter gene, transient expression experiments have shown that mutations of upstream cis-acting elements of the A1 promoter, or the deletion of an intron located within the 5 non-coding region, similarly affect expression in dicot or monocot protoplasts. The results reported here strongly suggest that this 5 intron is properly spliced in Zea mays. We show that two trans-acting factors, specifically interacting with an upstream activating sequence (the TEF 1 box), are present in nuclear extracts prepared from A. thaliana, Brassica rapa, Nicotiana tabacum and Z. mays. In addition, a DNA sequence homologous to the TEF 1 box, found at approximately the same location within a Lycopersicon esculentum EF-1 promoter, interacts with the same trans-acting factors. Homologies found between the A. thaliana and L. esculentum TEF 1 box sequences have allowed us to define mutations of this upstream element which affect the interaction with the corresponding trans-acting factors. These results support the notion that the activation processes of A. thaliana EF-1 genes have been conserved among angiosperms and provide interesting data on the functional structure of the TEF 1 box.     

The carbohydrases of Bacillus stearothermophilus NCIB 11412 and NCIB 10814

Summary Two strains (NCIB 11412 and NCIB 10814) of the thermophilic organism Bacillus stearothermophilus were found to produce complex carbohydrase systems. The enzyme activities in each system include -amylase as the major component, maltase, pullulanase, a minor amylase and cyclodextrinase. The latter three activities are produced in low yield in both strains. A crude enzyme preparation from each strain possessed maltogenic properties on hydrolysis of soluble starch. Following rigorous purification procedures, the purified major -amylase from either strain did not produce maltose as a major end-product of starch hydrolysis. However, a partially purified mixture of pullulanase, minor amylase and cyclodextrinase activities from NCIB 11412 and NCIB 10814 produced 56.4% and 62.0% maltose, respectively, from soluble starch.