[Cushing's syndrome during pregnancy : diagnostic and therapeutic difficulties]. / Le cas clinique du mois. Syndrome de Cushing au cours d'une grossesse : difficultés diagnostiques et thérapeutiques.

Cushing's syndrome (CS), which is often associated with infertility, exceptionally occurs in pregnancy, and markedly increases maternal and fetal morbidity and mortality. Gestational CS may be challenging. Indeed, symptoms of hypercorticism may overlap with physiological hyperactivity of the hypothalamus-pituitary-adrenal axis in normal pregnancy. This case report describes a pregnant patient that underwent a fertility treatment and developed a gestational CS due to an adrenocortical adenoma. Diagnosis of gestational CS was suspected at 13 weeks by a new onset of hypokalemia and arterial hypertension. A multidisciplinary approach was necessary during follow up. At 24 weeks, laparoscopic surgery retrieved a 4 cm adrenocortical adenoma. Cesarean surgery was successfully practiced at 31 weeks, because of preeclampsia. We discuss the differential diagnosis of hypokalemia and arterial hypertension during pregnancy and the diagnosis and management of gestational CS.

Le syndrome de Cushing (SC), déterminant fréquemment une infertilité, survient exceptionnellement au cours d´une grossesse. La présentation du SC au cours de la grossesse s'accompagne d'une plus grande morbimortalité maternelle et foetale. Son diagnostic représente un véritable défi pour le clinicien, car les symptômes de l'hypercorticisme se superposent aux modifications physiologiques induites par la stimulation de l`axe corticotrope lors de la grossesse. Nous rapportons le cas d'une patiente enceinte après une fécondation in vitro. A 13 semaines de grossesse, un SC gestationnel d'origine surrénalienne est suspecté dans le cadre d'une hypokaliémie et d'une hypertension artérielle inaugurales. Un suivi multidisciplinaire est instauré au cours de la grossesse. Une surrénalectomie gauche par voie laparoscopique est décidée à 24 semaines d'aménorrhée, avec l'exérèse complète d'un adénome cortical, de 4 cm de diamètre. La chirurgie par césarienne est pratiquée avec succès à 31 semaines de grossesse, car la patiente développait une pré-éclampsie. Nous discutons les différents diagnostics différentiels d'une hypokaliémie et d'une hypertension artérielle au cours de la grossesse et les modalités de prise en charge d´un SC gestationnel.

The genome of Desulfotalea psychrophila, a sulfate-reducing bacterium from permanently cold Arctic sediments.

Desulfotalea psychrophila is a marine sulfate-reducing delta-proteobacterium that is able to grow at in situ temperatures below 0 degrees C. As abundant members of the microbial community in permanently cold marine sediments, D. psychrophila-like bacteria contribute to the global cycles of carbon and sulfur. Here, we describe the genome sequence of D. psychrophila strain LSv54, which consists of a 3 523 383 bp circular chromosome with 3118 predicted genes and two plasmids of 121 586 bp and 14 663 bp. Analysis of the genome gave insight into the metabolic properties of the organism, e.g. the presence of TRAP-T systems as a major route for the uptake of C(4)-dicarboxylates, the unexpected presence of genes from the TCA cycle, a TAT secretion system, the lack of a beta-oxidation complex and typical Desulfovibrio cytochromes, such as c(553), c(3) and ncc. D. psychrophila encodes more than 30 two-component regulatory systems, including a new Ntr subcluster of hybrid kinases, nine putative cold shock proteins and nine potentially cold shock-inducible proteins. A comparison of D. psychrophila's genome features with those of the only other published genome from a sulfate reducer, the hyperthermophilic archaeon Archaeoglobus fulgidus, revealed many striking differences, but only a few shared features.

Genomic organization of the human CYP3A locus: identification of a new, inducible CYP3A gene.

Proteins encoded by the human CYP3A genes metabolize every second drug currently in use. The activity of CYP3A gene products in the general population is highly variable and may affect the efficacy and safety of drugs metabolized by these enzymes. The mechanisms underlying this variability are poorly understood, but they include gene induction, protein inhibition and unknown genetic polymorphisms. To better understand the regulation of CYP3A expression and to provide a basis for a screen of genetic polymorphisms, we determined and analysed the sequence of the human CYP3A locus. The 231 kb locus sequence contains the three CYP3A genes described previously (CYP3A4, CYP3A5 and CYP3A7), three pseudogenes as well as a novel CYP3A gene termed CYP3A43. The gene encodes a putative protein with between 71.5% and 75.8% identity to the other CYP3A proteins. The highest expression level of CYP3A43 mRNA is observed in the prostate, an organ with extensive steroid metabolism. CYP3A43 is also expressed in several other tissues including liver, where it can be induced by rifampicin. CYP3A43 transcripts undergo extensive splicing. The identification of a new member of the CYP3A family and the characterization of the full CYP3A locus will aid efforts to identify the genetic variants underlying its variable expression. This, in turn, will lead to a better optimization of therapies involving the numerous substrates of CYP3A proteins.

Molecular evolution of receptor-like kinase genes in hexaploid wheat. Independent evolution of orthologs after polyploidization and mechanisms of local rearrangements at paralogous loci.

Hexaploid wheat is a young polyploid species and represents a good model to study mechanisms of gene evolution after polyploidization. Recent studies at the scale of the whole genome have suggested rapid genomic changes after polyploidization but so far the rearrangements that have occurred in terms of gene content and organization have not been analyzed at the microlevel in wheat. Here, we have isolated members of a receptor kinase (Lrk) gene family in hexaploid and diploid wheat, Aegilops tauschii, and barley (Hordeum vulgare). Phylogenetic analysis has allowed us to establish evolutionary relationships (orthology versus paralogy) between the different members of this gene family in wheat as well as with Lrk genes from barley. It also demonstrated that the sequences of the homoeologous Lrk genes evolved independently after polyploidization. In addition, we found evidence for gene loss during the evolution of wheat and barley. Analysis of large genomic fragments isolated from nonorthologous Lrk loci showed a high conservation of the gene content and gene organization at these loci on the homoeologous group 1 chromosomes of wheat and barley. Finally, sequence comparison of two paralogous fragments of chromosome 1B showed a large number of local events (sequence duplications, deletions, and insertions), which reveal rearrangements and mechanisms for genome enlargement at the microlevel.

Analysis of 148 kb of genomic DNA around the wnt1 locus of Fugu rubripes.

The analysis of the sequence of approximately 150 kb of a genomic region corresponding to the wnt1 gene of the Japanese pufferfish Fugu rubripes confirms the compact structure of the genome. Fifteen genes were found in this region, and 26.6% of the analyzed sequence is coding sequence. With an average intergenic distance of <5 kb, this gene density is comparable to that of Caenorhabditis elegans. The compactness of this region corresponds to the reduction of the overall size of the genome, consistent with the conclusion that the gene number in Fugu and human genomes is approximately the same. Eight of the genes have been mapped in the human genome and all of them are found in the chromosomal band 12q13, indicating a high degree of synteny in both species, Fugu and human. Comparative sequence analysis allows us to identify potential regulatory elements for wnt1 and ARF3, which are common to fish and mammals.

The lack of a stress response in Hydra oligactis is due to reduced hsp70 mRNA stability.

Synthesis and degradation of hsp70 mRNA was examined and compared in Hydra species living in different habitats and showing different heat-shock response. Hydra oligactis is restricted to habitats of low temperature and relatively stable pH. We have shown previously that this species is unable to acquire thermotolerance [Bosch, T., Krylow, S., Bode, H. & Steele, R. (1988) Proc. Natl. Acad. Sci. USA 85, 7927-7931] and synthesizes significantly less heat-shock protein and hsp70 mRNA [Gellner, K., Praetzel, G. & Bosch, T. C. G. (1992) Eur J. Biochem. 210, 683-691] in response to stress than related species, such as Hydra bulgaris or Hydra magnipapillata, which are adapted to habitats of wide temperature range and variable water quality. To examine the mechanisms responsible for the differential heat-shock responses in these species, a construct containing H. magnipapillata hsp70 regulatory sequences fused to firefly luciferase was introduced into H. oligactis and H. magnipapillata polyps, and expression of luciferase examined. The results showed that luciferase can be expressed equally well in a heat-inducible manner in both species, suggesting that H. oligactis heat-shock factor can interact with H. magnipapillata heat-shock elements. Northern blots of alpha-amanitin-treated polyps demonstrated that the half-life of hsp70 mRNA in heat-shocked H. oligactis is drastically shorter than in H. magnipapillata. Thus, differences in hsp70 mRNA stability appear to be responsible for the habitat-correlated differences in the stress response in Hydra species.

Identification of an evolutionarily conserved 110 base-pair cis-acting regulatory sequence that governs Wnt-1 expression in the murine neural plate.

The generation of anterior-posterior polarity in the vertebrate brain requires the establishment of regional domains of gene expression at early somite stages. Wnt-1 encodes a signal that is expressed in the developing midbrain and is essential for midbrain and anterior hindbrain development. Previous work identified a 5.5 kilobase region located downstream of the Wnt-1 coding sequence which is necessary and sufficient for Wnt-1 expression in vivo. Using a transgenic mouse reporter assay, we have now identified a 110 base pair regulatory sequence within the 5.5 kilobase enhancer, which is sufficient for expression of a lacZ reporter in the approximate Wnt-1 pattern at neural plate stages. Multimers of this element driving Wnt-1 expression can partially rescue the midbrain-hindbrain phenotype of Wnt-1(-/-) embryos. The possibility that this region represents an evolutionarily conserved regulatory module is suggested by the identification of a highly homologous region located downstream of the wnt-1 gene in the pufferfish (Fugu rubripes). These sequences are capable of appropriate temporal and spatial activation of a reporter gene in the embryonic mouse midbrain; although, later aspects of the Wnt-1 expression pattern are absent. Genetic evidence has implicated Pax transcription factors in the regulation of Wnt-1. Although Pax-2 binds to the 110 base pair murine regulatory element in vitro, the location of the binding sites could not be precisely established and mutation of two putative low affinity sites did not abolish activation of a Wnt-1 reporter transgene in vivo. Thus, it is unlikely that Pax proteins regulate Wnt-1 by direct interactions with this cis-acting regulatory region. Our analysis of the 110 base pair minimal regulatory element suggests that Wnt-1 regulation is complex, involving different regulatory interactions for activation and the later maintenance of transgene expression in the dorsal midbrain and ventral diencephalon, and at the midbrain-hindbrain junction.

Cloning of a ras-related gene from Hydra which responds to head-specific signals.

Members of the Ras family of proteins are important components of signal transduction pathways responding to external signals and leading to changes in cell behavior. Analysis of two ras-related genes in the phylogenetically old metazoan Hydra indicates that in normal animals both genes are expressed in all body regions of the polyp. Upon head removal, however, the transcript level of one of the two genes, ras2, decreases rapidly in the upper gastric region which is adjacent to the former head. The decrease is transient and specific for ras2, since no changes could be observed in the transcript level of the related ras1 gene or any other gene. The disappearance of the ras2 mRNA can be prevented completely by brief exposure of decapitated polyps to the protein kinase C activator TPA, which previously was shown to be capable of converting gastric tissue into head tissue [Müller, W.A. In: Othmer, H.G. (Ed.) Experimental and Theoretical Advances in Biological Pattern Formation. Plenum Press, New York, NY, 1993, pp. 237-253]. The finding that Hydra ras2 expression is strongly dependent on a signal from the head provides the first evidence for ras expression being regulated in pattern formation.

Cloning and expression of a heat-inducible hsp70 gene in two species of Hydra which differ in their stress response.

A heat-inducible, intron-containing member of the hsp70 gene family has been isolated and characterized in Hydra magnipapillata and Hydra oligactis, two species previously shown [Bosch, T. C. G., Krylow, S. M., Bode, H. R. & Steele, R. E. (1988) Proc. Natl Acad. Sci. USA 85, 7927-7931] to differ in their stress response. The gene, hsp70.1, encodes a 654-amino-acid protein of predicted molecular mass 70 kDa with 78% amino acid identity to Xenopus HSP70. Northern-blot analysis revealed that polyps of H. oligactis accumulate significantly less hsp70.1 mRNA after heat shock than polyps of H. magnipapillata. In nuclear run-off experiments, we found that transcriptional induction of hsp70.1 expression in response to stress is similar in both species. Thus, the previously reported inability of H. oligactis to synthesize heat-shock proteins in response to stress is at least in part due to reduced stability of hsp70.1 mRNA during heat shock.