[Twin pregnancy and polymalformative syndrome by Enterovirus]. / Grossesse gémellaire et syndrome polymalformatif infectieux à Entérovirus.

Prenatal diagnosed congenital infection by Enterovirus is rarely described in the literature. A few casereports describe severe abnormalities observed by ultrasound that have led to spontaneous intrauterine demise or early death of the newborn. We report the case of a dichorionic diamniotic twin pregnancy. At 24 weeks of gestation, the second trimester ultrasound examination shows cardiac, brain and abdominal abnormalities in one of the fetuses. The other fetus has a normal appearance. "Standard" serological tests conducted on the mother are negative and amniocentesis reveals no genetic abnormality. After birth, Reverse Transcription Polymerase Chain Reaction (PCR) on samples of blood, ascites and stool reveals to be positive for Enterovirus in both newborns. Both are viable and exhibit severe brain abnormalities with severe neurological sequelae such as cerebral palsy, visual and hearing impairment. This case report illustrates the difficulty of prenatal diagnosis of congenital Enterovirus infection and informs about its possible neurological sequelae.

L'infection foetale précoce à Entérovirus (EV) est peu décrite dans la littérature. De rares cas rapportent de sévères anomalies vues à l'échographie qui conduisent à la mort foetale in utero ou au décès postnatal précoce. Nous présentons le cas d'une patiente présentant une grossesse gémellaire bichoriale biamniotique. L'échographie morphologique réalisée à 24 semaines d'aménorrhée révèle chez l'un des foetus des anomalies cardiaques, cérébrales et abdominales. Le second foetus présente un développement organique normal. Les sérologies «standards¼ réalisées chez la mère sont négatives et la ponction de liquide amniotique ne met pas en évidence d'anomalie génétique. A la naissance, une recherche d'Entérovirus par «Reverse Transcription Polymerase Chain Reaction¼ (RTPCR) se révèle positive pour les deux enfants. Ces derniers sont viables, mais présentent de sévères anomalies cérébrales causant des lourdes séquelles neurologiques. Ce cas clinique illustre la difficulté du diagnostic de l'infection congénitale à Entérovirus ainsi que ses conséquences potentielles.

Comparing brain activity patterns during spontaneous exploratory and cue-instructed learning using single photon-emission computed tomography (SPECT) imaging of regional cerebral blood flow in freely behaving rats.

Learning can be categorized into cue-instructed and spontaneous learning types; however, so far, there is no detailed comparative analysis of specific brain pathways involved in these learning types. The aim of this study was to compare brain activity patterns during these learning tasks using the in vivo imaging technique of single photon-emission computed tomography (SPECT) of regional cerebral blood flow (rCBF). During spontaneous exploratory learning, higher levels of rCBF compared to cue-instructed learning were observed in motor control regions, including specific subregions of the motor cortex and the striatum, as well as in regions of sensory pathways including olfactory, somatosensory, and visual modalities. In addition, elevated activity was found in limbic areas, including specific subregions of the hippocampal formation, the amygdala, and the insula. The main difference between the two learning paradigms analyzed in this study was the higher rCBF observed in prefrontal cortical regions during cue-instructed learning when compared to spontaneous learning. Higher rCBF during cue-instructed learning was also observed in the anterior insular cortex and in limbic areas, including the ectorhinal and entorhinal cortexes, subregions of the hippocampus, subnuclei of the amygdala, and the septum. Many of the rCBF changes showed hemispheric lateralization. Taken together, our study is the first to compare partly lateralized brain activity patterns during two different types of learning.

The human origin recognition complex protein 1 dissociates from chromatin during S phase in HeLa cells.

We investigated the association of human origin recognition complex (ORC) proteins hOrc1p and hOrc2p with chromatin in HeLa cells. Independent procedures including limited nuclease digestion and differential salt extraction of isolated nuclei showed that a complex containing hOrc1p and hOrc2p occurs in a nuclease-resistant compartment of chromatin and can be eluted with moderate high salt concentrations. A second fraction of hOrc2p that dissociates in vitro at low salt conditions was found to occur in a chromatin compartment characterized by its high accessibility to micrococcal nuclease. Functional differences between these two sites become apparent in HeLa cells that synchronously enter the S phase after a release from a double-thymidine block. The hOrc1p/hOrc2p-containing complexes dissociate from their chromatin sites during S phase and reassociate at the end of mitosis. In contrast, the fraction of hOrc2p in nuclease-accessible, more open chromatin remains bound during all phases of the cell cycle. We propose that the hOrc1p/hOrc2p-containing complexes are components of the human origin recognition complex. Thus, the observed cell cycle-dependent release of the hOrc1p/hOrc2p-containing complexes is in line with previous studies with Xenopus and Drosophila systems, which indicated that a change in ORC stability occurs after prereplication complex formation. This could be a powerful mechanism that prevents the rereplication of already replicated chromatin in the metazoan cell cycle.

The proliferation-specific human Ki-67 protein is a constituent of compact chromatin.

The human nuclear Ki-67 protein (Ki-67p) is expressed in proliferating, but not in quiescent, cells and is therefore widely used as a proliferation marker in histopathological research and practice. However, information regarding its intranuclear location is scarce and controversial. Here we describe the results of cell fractionation and nuclease digestion experiments using nuclei isolated from human HeLa cells in interphase. Ki-67p dissociates at 0.3-0.4 M NaCl from its nuclear binding sites, and gradient centrifugations indicate that the released Ki-67p is most likely a single molecular entity and not complexed to other proteins. In nuclei, prepared under physiological salt conditions, the binding sites are largely resistant against micrococcal nuclease. However, when prepared at very low ionic strengths, chromatin regions with associated Ki-67p become accessible to micococcal-nuclease-producing chromatin fragments that carry bound Ki-67p. We conclude that Ki-67p is a chromatin protein and resides at densely packed regions, probably heterochromatin. Our data provide a useful basis for further biochemical research on this human nuclear protein.