The NIMA-related kinase X-Nek2B is required for efficient assembly of the zygotic centrosome in Xenopus laevis.

Nek2 is a mammalian cell cycle-regulated serine/threonine kinase that belongs to the family of proteins related to NIMA of Aspergillus nidulans. Functional studies in diverse species have implicated NIMA-related kinases in G(2)/M progression, chromatin condensation and centrosome regulation. To directly address the requirements for vertebrate Nek2 kinases in these cell cycle processes, we have turned to the biochemically-tractable system provided by Xenopus laevis egg extracts. Following isolation of a Xenopus homologue of Nek2, called X-Nek2B, we found that X-Nek2B abundance and activity remained constant through the first mitotic cycle implying a fundamental difference in Nek2 regulation between embryonic and somatic cell cycles. Removal of X-Nek2B from extracts did not disturb either entry into mitosis or the accompanying condensation of chromosomes providing no support for a requirement for Nek2 in these processes at least in embryonic cells. In contrast, X-Nek2B localized to centrosomes of adult Xenopus cells and was rapidly recruited to the basal body of Xenopus sperm following incubation in egg extracts. Recruitment led to phosphorylation of the X-Nek2B kinase. Most importantly, depletion of X-Nek2B from extracts significantly delayed both the assembly of microtubule asters and the recruitment of gamma-tubulin to the basal body. Hence, these studies demonstrate that X-Nek2B is required for efficient assembly of a functional zygotic centrosome and highlight the possibility of multiple roles for vertebrate Nek2 kinases in the centrosome cycle.

The polo-like kinase Plx1 is required for M phase exit and destruction of mitotic regulators in Xenopus egg extracts.

Polo-like kinases (Plks), named after the Drosophila gene product polo, have been implicated in the regulation of multiple aspects of mitotic progression, including the activation of the Cdc25 phosphatase, bipolar spindle formation and cytokinesis. Genetic analyses performed in yeast and Drosophila suggest a function for Plks at late stages of mitosis, but biochemical data to support such a function in vertebrate organisms are lacking. Here we have taken advantage of Xenopus egg extracts for exploring the function of Plx1, a Xenopus Plk, during the cell cycle transition from M phase to interphase (I phase). We found that the addition of a catalytically inactive Plx1 mutant to M phase-arrested egg extracts blocked their Ca2+-induced release into interphase. Concomitantly, the proteolytic destruction of several targets of the anaphase-promoting complex and the inactivation of the Cdc2 protein kinase (Cdk1) were prevented. Moreover, the M to I phase transition could be abolished by immunodepletion of Plx1, but was restored upon the addition of recombinant Plx1. These results demonstrate that the exit of egg extracts from M phase arrest requires active Plx1, and they strongly suggest an important role for Plx1 in the activation of the proteolytic machinery that controls the exit from mitosis.

[Chemical colitis caused by glutaraldehyde]. / Colite chimique au glutaraldéhyde.

Glutaraldehyde disinfectant solution may be a cause of toxic chemical colitis. We report two cases. Ultrasonic features were studied in one case and mimic colonic ischemia, inflammatory and/or infectious colitis. These findings were colonic wall thickening especially mucosal (hypoechogenicity) and submucosal (hyperechogenicity) layers. This diagnosis should be discussed when one sees a patient with echographic findings of acute left-sided colitis just after uncomplicated colonic endoscopy.

Exploracion por cortes del tubo digestivo intra-abdominal. Aportes de la ecografia percut nea y de la tomograf!a computada en la practica cotidiana / Exploration by samples from the digestive intra-abdominal tube

La exploracion del tubo digestivo ha sido y continua siendo competencia de la endoscopia completada por la radiologia convencional, pero el tubo digestivo se ha transformado en inevitable en emagendopia por cortes. La ecografia computada no reemplazan absolutamente a las exploraciones digestivas clasicas pero participan en el diagnostico de las afecciones digestivas en dos grandres circunstancias: por una parte, el balance de extension loco-regional de una afeccion ya conocida (caso de figura la mas simple), y, por otra parte, el descubrimiento fortuito de una formacion intraabdominal de origen digestivo en ocasion de la exploracion ya sea de una masa abdominal ya sea de un sindrome doloroso abdominal cronico o agudo, ya sea de una alteracion del estado general o de una anemia. En la practica cotidiana, el radiologo se enfrenta a veces a problemas de dificil interpretacion: una masa intraabdominal, es de origen digestivo?, un engrosamiento parietal digestivo, se debe a un artefacto por defecto de preparacion o una lesion organica perietal digestiva y, en este ultimo caso, es una lesion tumoral o inflamatoria?

Exploracion por cortes del tubo digestivo intra-abdominal. Aportes de la ecografia percut nea y de la tomograf!a computada en la practica cotidiana / Exploration by samples from the digestive intra-abdominal tube

La exploracion del tubo digestivo ha sido y continua siendo competencia de la endoscopia completada por la radiologia convencional, pero el tubo digestivo se ha transformado en inevitable en emagendopia por cortes. La ecografia computada no reemplazan absolutamente a las exploraciones digestivas clasicas pero participan en el diagnostico de las afecciones digestivas en dos grandres circunstancias: por una parte, el balance de extension loco-regional de una afeccion ya conocida (caso de figura la mas simple), y, por otra parte, el descubrimiento fortuito de una formacion intraabdominal de origen digestivo en ocasion de la exploracion ya sea de una masa abdominal ya sea de un sindrome doloroso abdominal cronico o agudo, ya sea de una alteracion del estado general o de una anemia. En la practica cotidiana, el radiologo se enfrenta a veces a problemas de dificil interpretacion: una masa intraabdominal, es de origen digestivo?, un engrosamiento parietal digestivo, se debe a un artefacto por defecto de preparacion o una lesion organica perietal digestiva y, en este ultimo caso, es una lesion tumoral o inflamatoria?

[Tomographic study of the intra-abdominal digestive tract. Contributions of percutaneous echography and scanner in daily practice]. / Exploration par coupes du tube digestif intra-abdominal. Apports de l'échographie percutanée et du scanner en pratique quotidienne.

Endoscopy and radiological imaging are complementary. However the gastro-intestinal tract is routinely being imaged in CT and ultrasound, often performed for other indications. When an abnormality is discovered, several questions have to be addressed. Is the lesion due to a bowel abnormality? When bowel wall thickening is present, is it due to poor opacification or is it due to inflammation or tumor? Circumferential symmetrical thickening is more in favor of an inflammatory lesion, while focal asymmetrical thickening is more in favor of a neoplastic lesion. Inflammatory and lymphomatous lesion can have similar appearances. Guidelines to aid in diagnostic interpretation of gastrointestinal lesions are discussed, including features of appendicitis and obstruction.

Both cyclin A and cyclin E have S-phase promoting (SPF) activity in Xenopus egg extracts.

Extracts of activated Xenopus eggs in which protein synthesis has been inhibited support a single round of chromosomal DNA replication. Affinity-depletion of cyclin dependent kinases (Cdks) from these extracts blocks the initiation of DNA replication. We define 'S-phase promoting factor' (SPF) as the Cdk activity required for DNA replication in these Cdk-depleted extracts. Recombinant cyclins A and E, but not cyclin B, showed significant SPF activity. High concentrations of cyclin A promoted entry into mitosis, which inhibited DNA replication. In contrast, high concentrations of cyclin E1 promoted neither nuclear envelope disassembly nor full chromosome condensation. In the early embryo cyclin E1 complexes exclusively with Cdk2 and cyclin A is complexed predominantly with Cdc2; only later in development does cyclin A associate with Cdk2. We show that baculovirus-produced complexes of cyclin A-Cd2, cyclin A-Cdk2 and cyclin E-Cdk2 could each provide SPF activity. These results suggest that although in the early Xenopus embryo cyclin E1-Cdk2 is sufficient to support entry into S-phase, cyclin A-Cdc2 provides a significant additional quantity of SPF as its levels rise during S phase.

[Acute pancreatitis disclosing an uncommon form of annular pancreas]. / Pancréatite aiguë révélant une forme particulière de pancréas annulaire.

We report a case of an acute pancreatitis revealing an annular pancreas associated with a pancreas divisum. Diagnosis was performed by endoscopic retrograde pancreatography with successful injection of major and minor papillae. Coexistence of pancreas divisum and annular pancreas is a rare congenital anomaly. Our case is original because the annular duct system encircling the duodenum is the ventral pancreas duct.

The 5' flanking region of the rat LAP (C/EBP beta) gene can direct high-level, position-independent, copy number-dependent expression in multiple tissues in transgenic mice.

The efficiency and tissue-specificity of transgene expression in animals is usually subject to the position of integration into the host chromatin. We have discovered that a 2.8kbp fragment flanking the rat gene encoding the transcription factor LAP (C/EBP beta) directs position-independent, copy number-dependent expression in transgenic-mouse livers. Concomitantly, the DNAse I hypersensitivity pattern normally observed in the liver is established in the integrated transgene construct demonstrating that this region is capable of creating chromatin structures equivalent to the endogenous situation. These observations are reminiscent of the locus control regions (LCR) described for several genes. Additionally, this LAP element functions with both intron-less and intron-containing genes. The tissue specificity of this element, however, is not restricted to liver. The 2.8kbp region is capable of allowing position-independent, copy number-dependent expression in brain, kidney, heart, spleen, and lung, but in a construct-dependent manner. This is, to our knowledge, the first transcription factor gene with which a cis-linked LCR-like element has been associated.

CCAAT/enhancer-binding protein mRNA is translated into multiple proteins with different transcription activation potentials.

The CCAAT/enhancer-binding protein (C/EBP) alpha is a leucine zipper protein that is preferentially expressed in certain cell types, such as adipocytes and hepatocytes. Here we show that C/EBP alpha mRNA is translated into two major proteins, C/EBP-42 and C/EBP-30, that differ in their content of N-terminal amino acid sequences. These results are best explained by a ribosome-scanning mechanism in which a fraction of ribosomes ignore the first two AUGs and initiate translation at an AUG located 351 nt downstream of the first one. Because C/EBP-30, the translation product initiated at the third AUG, is devoid of the potent transcription-activation domain contained in C/EBP-42, the former protein stimulates transcription from the mouse albumin promoter much less efficiently than the latter. The gene encoding the liver-enriched transcriptional-activator protein LAP (C/EBP-beta) has also been shown to issue two proteins, LAP and the liver-enriched transcriptional-inhibitory protein LIP, with different transcription-activation potentials. The production of multiple proteins from a single mRNA is not only shared between different C/EBP family members but also appears to be conserved in vertebrate evolution.

[Isolated intramural hematoma of the sigmoid. A rare complication of anticoagulant treatment]. / Hématome intra-mural isolé du sigmoïde. Une complication rare du traitement anticoagulant.

The authors report a case of intra-mural hematoma of the sigmoid associated with anticoagulant therapy. The small intestine is the site of predilection for intra-mural hematoma and the colonic site is very unusual. Our case was revealed by an obstructive syndrome. The diagnosis, suggested by the increased prothrombin time, was confirmed by ultrasonography and endoscopy. The treatment was symptomatic with nasogastric suction and correction of any hemostatic disorders.

A liver-enriched transcriptional activator protein, LAP, and a transcriptional inhibitory protein, LIP, are translated from the same mRNA.

LAP, a transcriptional activator, and LIP, a transcriptional repressor, are translated from a single mRNA species by using two AUGs within the same reading frame. These two proteins share the 145 C-terminal amino acids that contain the basic DNA-binding domain and the leucine zipper dimerization helix. Probably owing to its higher affinity for its DNA cognate sequences, LIP can attenuate the transcriptional stimulation by LAP in substoichiometric amounts. As revealed by transient transfection experiments, a moderate increase in the LAP/LIP ratio results in a significantly higher transcriptional activation of an appropriate target gene. The LAP/LIP ratio increases about 5-fold during terminal rat liver differentiation and is thus likely to modulate the activity of LAP in the intact animal.

[Intra-duodenal development of low choledochal diverticula. Apropos of 2 cases]. / Développement intraduodénal des diverticules du bas cholédoque. A propos de deux observations.

Two cases of intraduodenal development of a low choledochal diverticulum were observed during the last ten years. Preoperative diagnosis of this biliary malformation is difficult. Clinical presentation consisted of chronic upper abdominal pain and high gastrointestinal obstruction, without either cholangitis or pancreatitis. In both patients, treatment consisted of resection of the diverticulum and suture of its neck via a transduodenal approach. The post-operative course was uneventful and long-term follow-up (2 and 11 years) is satisfactory, showing that cure has been achieved by means of this simple and radical procedure. This particular biliary anomaly must therefore be distinguished from other diverticula of the common bile duct, because of its clinical presentation, diagnostic approach and treatment required.

[Acute pancreatitis and viral hepatitis A. Report of a case]. / Pancréatite aiguë et hépatite virale A. A propos d'un cas.

We are reporting the case of a patient with acute pancreatitis associated with viral A hepatitis with satisfactory recovery. To our knowledge, two similar cases have been reported.

LAP, a novel member of the C/EBP gene family, encodes a liver-enriched transcriptional activator protein.

A gene, encoding a liver-enriched transcriptional activator protein (LAP) has been isolated. LAP is a 32-kD protein that stimulates the transcription of chimeric genes containing albumin D-promoter elements both in vivo and in vitro. LAP shares extensive sequence homology (71%) in its DNA-binding and leucine zipper domains with C/EBP. As a consequence, these two proteins show an indistinguishable DNA-binding specificity and readily heterodimerize. In addition, both genes, lap and cebp, are devoid of intervening sequences. Although correctly initiated transcripts from the LAP gene accumulate in the six examined tissues--liver, lung, spleen, kidney, brain, and testis--LAP protein is highly enriched in liver nuclei. Thus, the preferential accumulation of LAP protein in liver appears to be regulated post-transcriptionally.