Human immunodeficiency virus type 1 Vpr is a positive regulator of viral transcription and infectivity in primary human macrophages.

It is currently well established that HIV-1 Vpr augments viral replication in primary human macrophages. In its virion-associated form, Vpr has been suggested to aid efficient translocation of the proviral DNA into the cell nucleus. Although Vpr growth-arrests dividing T cells, the relevance of this biological activity in nondividing macrophages is unclear. Here we use Vpr-mutants to demonstrate that the molecular determinants involved in G2-arresting T cells are also involved in increasing viral transcription in macrophages, even though these cells are refractive to the diploid DNA status typical of G2 phase. Our results suggest that the two phenotypes, namely the nuclear localization and the G2-arrest activity of the protein, segregate functionally among the late and early functions of Vpr. The nuclear localization property of Vpr correlates with its ability to effectively target the proviral DNA to the cell nucleus early in the infection, whereas the G2-arrest phenotype correlates with its ability to activate viral transcription after establishment of an infection. These two functions may render Vpr's role essential and not accessory under infection conditions that closely mimic the in vivo situation, that is, primary cells being infected at low viral inputs.

Perceptual priming does not transfer interhemispherically in the acallosal brain.

Acallosal participants usually do not display any disconnection signs in tasks requiring an explicit or declarative type of response. They can accurately compare stimuli placed in each hand and they perform normally on lateralized recognition tasks. They, however, show impairment in tasks assessing interdependent motor control, bilateral coordination and they are also unable to intermanually transfer an implicit procedural motor skill. These deficits suggest that compensation might be limited when a motor component is involved. Alternately, it is also possible that interhemispheric transmission in callosal agenesis might be limited when implicit or unconscious processes are involved (Berlucchi et al. in Neuropsychologia 33:923-936, 1995; De Guise et al. in Brain 122:1049-1062, 1999). The aim of the present study was to assess interhemispheric transfer in two distinct nondeclarative tasks, namely visuoperceptual skill learning and perceptual priming, with a lateralized version of the fragmented picture task developed by Snodgrass et al. (Behav Res Methods Inst Comp 19:270-274, 1987) that did not involve any motor component. The performance of five acallosal and one early-callosotomized individuals was compared to that of control participants divided into four groups (n = 10) according to which hemisphere was trained (left or right) and which response mode was used (manual or verbal). Visuoperceptual skill learning was observed in all control groups except for the group submitted to training of the left hemisphere in the manual modality of response. The acallosal and early-callosotomized participants did not show any implicit learning of the visuoperceptual skill on any of the conditions. The evaluation of the perceptual priming effect in the second part of the testing revealed that the priming effect was restricted to the trained hemisphere in participants without corpus callosum, as opposed to all neurogically intact participants who presented interhemispheric transfer of the priming effect. These findings indicate that the compensatory pathways, most probably subcortical commissures, are insufficient to allow interhemispheric transfer of perceptual priming, confirming the limits of neural plasticity in the absence of the corpus callosum. They also support the dissociation between declarative and nondeclarative memory in the split-brain and acallosal participants suggested by Berlucchi et al. (1995) and observed by De Guise et al. (Brain 122:1049-1062, 1999). These results are further discussed within the context of neurobiological theories of memory systems.

Human immunodeficiency virus type 1 vpr protein transactivation function: mechanism and identification of domains involved.

The human immunodeficiency virus type 1 (HIV-1) Vpr protein is a virion-associated protein that localizes in the nucleus of infected cells. Vpr has been shown to facilitate HIV infection of non-dividing cells such as macrophages by contributing to the nuclear translocation of the pre-integration complex. More recently, Vpr expression has been shown to induce an accumulation of cells at the G2 phase of the cell-cycle. We have previously reported that Vpr stimulates reporter gene expression directed from the HIV-1 long terminal repeat (LTR) as well as from heterologous viral promoters. However, the mode of action of Vpr-mediated transactivation remains to be precisely defined. We report here that, for a constant amount of transfected DNA, the level of chloramphenicol acetyltransferase (CAT) mRNA is increased in Vpr-expressing cells using either HIV-1 or a murine leukemia virus (MLV) SL3-3 LTR-CAT reporter construct. Moreover, this Vpr-mediated transactivation requires that promoters direct a minimal level of basal expression. Our mutagenic analysis indicates that the transactivation mediated by Vpr is not dependent on the ability of the protein to localize in the nucleus or to be packaged in the virions. Interestingly, all transactivation-competent Vpr mutants were still able to induce a cell-cycle arrest. Conversely, transactivation-defective mutants lost the ability to mediate cell-cycle arrest, implying a functional relationship between these two functions. Overall, our results indicate that the G2 cell-cycle arrest mediated by Vpr creates a cellular environment where the HIV-1 LTR is transcriptionally more active.

Evaluation of the use of a protocol in the antimicrobial treatment of intra-abdominal sepsis.

A protocol was established aimed at limiting the duration of antimicrobial therapy in two patient groups with peritonitis. One group had perforated or gangrenous appendicitis and the other non-appendiceal disease. The duration of treatment given to patients treated according to the protocol was compared retrospectively to that of similar patients treated without the protocol. Patients with perforated or gangrenous appendicitis required significantly less antimicrobial therapy than those with peritonitis due to non-appendiceal disease. In non-appendiceal intra-abdominal sepsis the use of the protocol was associated with a significantly reduced duration of antimicrobial therapy, compared with that observed without the protocol.

Acetylcholinesterase activity in copepods (Tigriopus brevicornis) from the Vilaine River estuary, France, as a biomarker of neurotoxic contaminants.

From April 1997 to June 1998, 14 measurements of acetylcholinesterase (AChE) enzymatic activity were performed with the copepod, Tigriopus brevicornis, collected at five stations in the Vilaine River estuary (South Brittany, France). Simultaneously, four chemical analyses of triazines and one analysis of total pesticides in water were undertaken. AChE activity levels in T. brevicornis were compared to the levels measured at a reference site not exposed to effluents from Vilaine River. Results reveal significant differences between AChE activity levels depending on location of stations in the plume of the river with an increasing gradient of activity from the upstream to the downstream stations, thus indicating that neurotoxic contaminants are mainly brought by the river. The average degree of AChE inhibition between the reference site and the most upstream site is 70-80% during spring in 1997 and 1998. In May 1997, live copepods from the different sites were brought back and transferred to clean seawater. After 14 days, recovery of AChE activity was almost total when compared to the control. Moreover, using a linear regression model and the atrazine concentration as marker of the presence of pesticides, low levels of AChE activity were significantly explained by atrazine concentration in water.

[Diagnostic criteria of autism and Asperger's syndrome: similarities and differences]. / Les critères diagnostiques de l'autisme et du syndrome d'Asperger: similitudes et différences.

The American Psychiatric Association's last version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; APA, 1994) identifies within pervasive developmental disorders five subgroups: (a) autistic disorder; (b) Rett's disorder; (c) childhood disintegrative disorder; (d) Asperger's disorder's and (e) pervasive developmental disorder not otherwise specified. However, the diagnosis of the different sub-groups is difficult to establish, particularly between autistic disorder and Asperger's disorder. This article exposes the diagnostic criteria of autism and Asperger's syndrome in order to illustrate the similarities and differences between the two disorders.

ATP and the autonomy of the contractile vacuole in Amoeba proteus.

Contractile vacuole function in amoebae treated with immobilizing (5 mM) and nonimmobilizing (0.125 mM) concentrations of ATP has been studied. In ATP-immobilized amoebae, most vacuolar parameters are accelerated, especially the rate of output which passes from 30 to 70 micron3/sec. This favors the concept of an autonomous vacuole, fully functional in the absence of any bulk contribution to it from remote points of the cell. A lower concentration of ATP (0.125 mM), which does not inhibit movement, causes a still greater acceleration of vacuolar function. Work is in progress to elucidate the site and mode of action of exogenous ATP on Amoeba.

[A controlled-temperature microscope stage for extended observations of living materials (author's transl)]. / Un modèle de surplatine à température controlée pour les observations microscopiques prolongées de matériel vivant.

We have designed a controlled-temperature stage for the observations of live microorganisms under all magnifications of the compound microscope. The use of water-immersion objectives eliminates the need for a cover-slip and permits interventions such as liquid medium changes, microsurgery or the insertion of microelectrodes. Simple in design and relatively inexpensive this stage has an observation area of 50 X 75 mm.

Enhancement of retroviral production from packaging cell lines expressing the human immunodeficiency type 1 VPU gene.

The HIV-1 Vpu protein stimulates virus production by enhancing the release of viral particles from infected cells. Interestingly, Vpu was also shown to enhance the release of capsids produced by gag gene contructs of other retroviruses that lack a Vpu-like activity. To investigate the effect of Vpu expression on viral particle production in retroviral packaging cell line, we developed the Damp-VpuP cell line in which vpu expression is under the control of the tetracycline-responsive promoter. Retroviral production was measured by dosage of virion-associated reverse transcriptase activity, by capsid protein immuno-detection in cell-free supernatants and by evaluating the transfer of antibiotic resistance to target cells. Induction of the Damp-VpuP cell line caused a 40-fold increase in the titer of infectious virus-like particles when compared with control cell lines. This increase in viral titer was not the result of a clonal effect nor was it a consequence of high selective pressure but rather the effect of a Vpu-mediated enhancement of viral particle production. Similar results using the third generation psi CRIP packaging cell line confirmed these findings. Constitutive expression of vpu caused a 13-fold increase in viral titer in this packaging cell line. These results indicate that the expression of HIV-1 vpu in retroviral packaging cell lines can significantly improve the titers of infectious retroviral particles.

MuLV-based vectors pseudotyped with truncated HIV glycoproteins mediate specific gene transfer in CD4+ peripheral blood lymphocytes.

Human immunodeficiency virus (HIV) infection ultimately leads to the destruction of the CD4+ lymphocyte subset and the onset of AIDS. In recent years, several gene therapy procedures making use of retroviral vectors that selectively target HIV susceptible cells have been proposed in order to interfere with HIV productive infection. However, the HIV glycoproteins' inability to be incorporated in other heterologous retroviruses considerably limits true HIV cell tropism of such vectors. We now report the use of murine leukemia virus (MuLV) viral particles harboring a truncated form of the HIV glycoprotein for specific gene delivery. Reporter lacZ gene transfer was determined to be appropriately specific to CD4+ cells when HeLaCD4 cells or peripheral blood lymphocytes (PBLs) were infected with these pseudotyped MuLV virus vectors. In contrast, MuLV viruses harboring amphotropic MuLV envelope glycoproteins displayed a broad and nonspecific infection of PBL subpopulations. This new approach, taking advantage of the ability of truncated HIV envelope glycoproteins to be incorporated into heterologous retroviral particles, may foreseeably be used in future interventions based on the coordinated delivery of therapeutic gene products specifically to cell types susceptible to HIV infection.

Mortality and LC50 values for several stages of the marine copepod Tigriopus brevicornis (Müller) exposed to the metals arsenic and cadmium and the pesticides atrazine, carbofuran, dichlorvos, and malathion.

The toxicity of three insecticides (carbofuran, dichlorvos, malathion), an herbicide (atrazine), and two metals (arsenic and cadmium) to ovigerous females, copepodids, and nauplii of Tigriopus brevicornis was determined by 96-h semistatic (or static-renewal) bioassays. Freshly prepared aqueous stock solutions of these pesticides and metals were diluted to appropriate concentrations. Mortalities were recorded and test solutions were changed completely each day up to 96 h. The rate of mortality was analyzed for linear regressions, and LC50 values were determined by probit analysis. LC50 values for ovigerous T. brevicornis females were 153.2 micrograms liter-1 for atrazine, 59.9 micrograms liter-1 for carbofuran, 47.9 micrograms liter-1 for cadmium, 27.5 micrograms liter-1 for arsenic, 24.3 micrograms liter-1 for malathion, and 4.6 micrograms liter-1 for dichlorvos. Comparison of the overall toxicities of these pesticides and metals indicated that dichlorvos was the most toxic substance to T. brevicornis, followed by malathion, arsenic, cadmium, carbofuran, and atrazine. Available LC50 data indicate that marine copepods are more sensitive to pollutants than Daphnia magna, Acartia tonsa, and Tisbe battagliai, or as sensitive as the mysid Mysidopsis bahia.

Vpr stimulates viral expression and induces cell killing in human immunodeficiency virus type 1-infected dividing Jurkat T cells.

In this study we investigated the effects of Vpr during human immunodeficiency virus (HIV) infection of proliferating Jurkat T cells by using a vesicular stomatitis virus envelope G glycoprotein pseudotyped HIV superinfection system. We observe that the expression of Vpr results in a severe reduction in the life span of HIV type 1 (HIV-1)-infected dividing T cells in culture. In agreement with a recent report (S. A. Stewart, B. Poon, J. B. M. Jowett, and I. S. Chen, J. Virol. 71:5579-5592, 1997), we show that events characteristic of apoptotic cell death are involved in the Vpr-mediated cytopathic effects. Our results also show that infection with viruses expressing the wild-type vpr gene results in an increase in viral gene expression and production. Interestingly, the effects of Vpr on cell viability and on viral gene expression both correlate with the ability of the protein to induce a cell cycle arrest in the G2/M phase. Mutagenesis analyses show that the C terminus of Vpr is essential for these biological activities. Although the role of Vpr is currently associated with the infection of nondividing cells, our results suggest that Vpr can also directly increase viral replication in vivo in infected dividing T cells. Furthermore, these in vitro observations suggest that Vpr-mediated cytotoxic effects could contribute to the CD4+ depletion associated with AIDS progression.