The death factors: a combinatorial analysis

This paper presents theoretical and computational tools to understand how a small group of proteins, the death factors, are involved in widely different behavior of the cell. Experiments were done using a virtual laboratory that can simulate cellular response to different external stimuli. WARNING: It is not certain which of the theoretical protein clusters described here really occur in nature. In addition, the rules of cluster assembly are combinatorial, and thus an oversimplification to describe the real situation.

Diethylstilbestrol regulates trophoblast stem cell differentiation as a ligand of orphan nuclear receptor ERR beta

The orphan nuclear receptor ERR beta is expressed in undifferentiated trophoblast stem cell lines and extraembryonic ectoderm, and genetic ablation of ERR beta results in abnormal trophoblast proliferation and precocious differentiation toward the giant cell lineage. Here, we show that the synthetic estrogen diethylstilbestrol (DES) promotes coactivator release from ERR beta and inhibits its transcriptional activity. Strikingly, treatment of trophoblast stem cells with DES led to their differentiation toward the polyploid giant cell lineage. In addition, DES-treated pregnant mice exhibited abnormal early placenta development associated with an overabundance of trophoblast giant cells and an absence of diploid trophoblast. These results define a novel pathway for DES action and provide evidence for steroidlike control of trophoblast development.

Mutant torsinA, responsible for early-onset torsion dystonia, forms membrane inclusions in cultured neural cells

Early-onset torsion dystonia is a hereditary movement disorder thought to be caused by decreased release of dopamine into the basal ganglia, without apparent neuronal degeneration. Recent cloning of the gene responsible for this disease, TOR1A (DYT1), identified the encoded protein, torsinA, as a member of the AAA+ superfamily of chaperone proteins and revealed highest levels of expression in dopaminergic neurons in human brain. Most cases of this disease are caused by a deletion of one glutamic acid residue in the C-terminal region of the protein. Antibodies generated against torsinA revealed expression of a predominant immunoreactive protein species similar to the predicted size of 37.8 kDa in neural, glial and fibroblastic lines by western blot analysis. This protein is N-glycosylated with high mannose content and not, apparently, phosphoryl-ated. Overexpression of torsinA in mouse neural CAD cells followed by immunocytochemistry, revealed a dramatically different pattern of distribution for wild-type and mutant forms of the protein. The wild-type protein was found throughout the cytoplasm and neurites with a high degree of co-localization with the endoplasmic reticulum (ER) marker, protein disulfide isomerase. In contrast, the mutant protein accumulated in multiple, large inclusions in the cytoplasm around the nucleus. These inclusions were composed of membrane whorls, apparently derived from the ER. If disrupted processing of the mutant protein leads to its accumulation in multilayer membranous structures in vivo, these may interfere with membrane trafficking in neurons.

Identification of a common site of provirus integration in radiation leukemia virus-induced T-cell lymphomas in mice

The BL/VL(3) Kaplan radiation leukemia virus (RadLV-VL(3)) is a nondefective retrovirus that induces T cell lymphomas in several strains of mice. By using DNA probes derived from RadLV/VL(3) provirus-flanking sequences cloned from the BL/VL(3) cell line, we identified a DNA region rearranged in 5 of 19 tumors analysed (25%). All proviruses were integrated in the same 5'-to-3' orientation in a small DNA region called Kis1 (Kaplan integration site 1). This region was localized on distal mouse chromosome 2 in a region not previously identified as important to lymphomagenesis. The cells rearranged at the Kis1 locus represent a clonal subpopulation of the clonal tumor masses examined, indicating a probable role of Kis1 in tumor progression.

The GATA-1 and Spi-1 transcriptional factors bind to a GATA/EBS dual element in the Fli-1 exon 1

Fli-1 is a proto-oncogene which is rearranged in tumors induced by three different retroviruses, Cas-Br-E, F-MuLV, and 10A1. This gene is a member of the Ets gene family, a class of transcription factors that recognize and bind to a DNA motif known as the Ets binding site (EBS). Our laboratory has previously cloned and characterized the promoter region of both human and mouse Fli-1 genes. We had then identified several regulatory elements conserved between the two species. Two of them, an exon 1 GATA/EBS dual element and an EBS element located in the 5' end of intron 1, were analysed in the present study. EMSA analysis performed with nuclear extracts from different cell lines showed that the EBS element in intron 1 (EBSi) was bound by one potential Ets-related ubiquitous factor. The GATA/EBS element was bound by several factors that seemed Ets-related, one of which was found to be specifically expressed in hematopoietic cells. the GATA/EBS dual element was thus chosen for further analysis. A human Fli-1-derived genomic fragment containing the GATA/EBS led to enhanced transcription when positioned upstream of the SV40 promoter in the erythroleukemic HEL cell line. In addition, an increasing number of GATA/EBS oligonucleotides upstream of this same promoter resulted in a copy number-dependent increase in luciferase activity which was greatly reduced when the EBS consensus sequence was mutated. One of the factors binding to the GATA/EBS region was identified to be Spi-1 by supershift analysis and was also shown to bind to the EBS element of the human Ets-2 gene. Supershift analysis also demonstrated the binding of the GATA-1 factor to the GATA/EBS dual element. Our results suggest that Spi-1 and GATA-1 might play a key role in the regulation of Fli-1.

[Apprenticeship in radiology at the University Hospital Center in Grenoble: research on the most effective methods]

From analyses of strengths and weaknesses of the apprenticeship of radiology in France, of existing pedagogic methods, of time constraints within clinical settings and of scientific theories of teaching and learning, the authors define objectives that teaching should target and propose a new method of instruction problem and practise-based. The method appears applicable in French radiology departments. It should forster early acquisition by residents of professional attitudes and way of thinking, and make them active self-directed learners.

The attitudes of rural Minnesota family physicians toward nurse practitioners and physician assistants

Increased use of nurse practitioners and physician assistants has been promoted as a possible solution to the shortage of primary care providers in rural locations. If the use of nonphysician providers is to be optimized in these areas, awareness and acceptance of their capabilities by rural family physicians is essential. This study surveyed the attitudes of rural Minnesota family physicians toward the use of physician assistants and nurse practitioners. Forty-six percent of the 600 rural family physicians surveyed responded to the questionnaire. Approximately 90 percent of responding physicians indicated a high degree of confidence in the abilities of nonphysician providers in the areas of preventive and routine care; some concern was expressed about the proficiency of nonphysician providers taking call, covering the emergency room, and doing hospital rounds--activities that involve a broader base of clinical knowledge and diagnostic skills. Other concerns were an increased workload for physicians due to their assumed supervisory roles, an increase in complexity of cases seen by physicians, increased physician liability, job competition between nonphysician providers and physicians, and the lack of educational opportunities and supervisory guidelines for physicians regarding collaborative relationships. Appropriate roles for family physicians, nurse practitioners and physician assistants are not well-defined in the minds of respondents, and it appears future acceptance and practice patterns will depend on how these roles are established and accepted.

Consultation skills in radiology: a qualitative study

OBJECTIVE

Consultation is an important part of radiologic practice. Recently, many concerns have been expressed about the lack of emphasis on consultation skills as part of the training requirements for radiologists. In order to improve the teaching and assessment of trainees, we designed a qualitative study to specify the consultation skills expected from a trainee by the end of residency.

METHODS

Three successive focus groups were held with professors of radiology, residents in radiology, and referring physicians. Participants were asked to identify the various competencies required from radiologic consultants (1) spontaneously, (2) by reacting to a previously generated list, and (3) by reacting to common clinical problems encountered in radiology.

RESULTS

Consultation skills thus identified were organized in a framework consisting of 2 groups: observable skills and standards of practice. Observable skills were subdivided into 5 "problem-setting" skills and 6 "results-management" skills. Seven qualities and attitudes identified were combined under the rubric "standards of practice."

CONCLUSION

The specification of these abilities and competencies through a consensus process should permit the teaching of these skills and their evaluation through objective, structured clinical examinations.

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.

The putative alpha helix 2 of human immunodeficiency virus type 1 Vpr contains a determinant which is responsible for the nuclear translocation of proviral DNA in growth-arrested cells

Several viral determinants were shown to play a role in the ability of human immunodeficiency virus type 1 (HIV-1) to infect nondividing cells. In particular, Vpr and Gag matrix (MA) were recognized to be involved in the nuclear transport of the viral preintegration complex. The goal of the present study was to evaluate the ability of isogenic HIV-1 viruses harboring different vpr and gag genes to infect nondividing cells. Surprisingly, our results reveal that the introduction of mutations in the MA nuclear localization signal marginally affected the ability of proviruses to establish infection in growth-arrested HeLa or MT4 cells. In contrast, we show that in our experimental system, the absence of Vpr expression leads to a reduction in viral infectivity and production which correlates with a decrease in the synthesis and nuclear transport of proviral DNA as determined by PCR analysis. Moreover, our data demonstrate that this reduction of viral replication is also observed with proviruses containing different mutated Vpr alleles. In particular, the Vpr Q65E mutant, which contains a substitution in the second predicted amphipathic alpha-helical structure located in the central region of the protein, is associated with an impairment of the protein nuclear localization and a concomitant reduction of the nuclear transport of proviral DNA. The results of this study provide evidence that a putative amphipathic alpha-helical structure in the central region of Vpr contains a determinant involved in the nuclear translocation of the preintegration complex in nondividing cells.

Human immunodeficiency virus type 1 Vpr localization: nuclear transport of a viral protein modulated by a putative amphipathic helical structure and its relevance to biological activity

Protein import into the nucleus is generally considered to involve specific nuclear localization signals (NLS) though it is becoming increasingly clear that efficient and well controlled import of proteins which lack a canonical NLS also occurs in cells. Human immunodeficiency virus type 1 (HIV-1) Vpr is one such protein which does not have an identifiable canonical NLS and yet efficiently localizes to the nuclear compartment. Here, we use confocal microscopy to demonstrate that mutations in the putative central hydrophobic helix of Vpr result in the retention of the protein in highly localized ring-like structures around the nuclear periphery with striking impairment in their ability to enter the nuclear interior. By characterizing other biological activities associated with this protein, such as its ability to incorporate into budding virions and its ability to arrest cells in G2, we show that this helical domain is specific for the nuclear translocation of the protein with very little effect on these other functions. Interestingly, however, perturbation of this helical motif also perturbs the protein's ability to augment viral replication in primary human macrophages indicating that the integrity of this secondary structure is essential for optimal infection in these non-dividing cells.

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.

Characterization of the cytotoxic factor(s) released from thymic dendritic cells upon human immunodeficiency virus type 1 infection

We previously demonstrated that infection of primary human thymic dendritic cells (DCs) with laboratory strains of HIV leads to the release of soluble factor(s) which induced thymocyte killing. In the present paper, we extend the characterization of this process. Our results reveal that primary HIV-1 isolates are similarly able to induce the production of cytotoxic factor(s) from thymic DCs and that the release of such factor(s) is dependent on viral infection. Interestingly, we observed that CD4+ and CD8+ purified thymocyte subsets, and activated PBMCs are susceptible to the cytotoxic activity, whereas freshly isolated resting PBMCs are resistant to this effect. Cycloheximide treatment prevents the killing of thymocytes exposed to HIV-infected DC supernatant, revealing that this form of cell death is an active biological process requiring protein synthesis. Finally, our data suggest that FasL and TNF alpha could both participate in the killing process. These in vitro observations provide a plausible model, whereby HIV-infected DCs can play a role in vivo in the induction of uninfected thymocyte killing.

Combinatorial tools for the analysis of transcriptional regulation

In this paper, we discuss virtual experiments for the study of major regulatory processes such as translation, signalization or transcription pathways. An essential part of these processes is the formation of protein clusters held together by a small number of binding domains that can be shared by many different proteins. Analysis of these clusters is complicated by the vast number of different arrangements of proteins that can trigger a specific reaction. We propose combinatorial tools that can help predict the effects on the rate of transcription of either changes in transcriptional factors concentration, or due to the introduction of chimeras combining domains not usually present on a protein.

PGE2, but not TGF beta 2, in rabbit blastocoelic fluid regulates the cytotoxic activities of NK and LAK cells

Spontaneous and induced fetal resorptions have been associated with the infiltration and activation of GM1-positive natural killer (NK)-like cells. Predominance of these cells in the decidua and their reduced lytic activity suggest that regulation of their killing activity could be important for the survival of the fetus. It has therefore been hypothesized that the embryo was regulating NK lytic activity. To test this hypothesis, human and rabbit lymphocytes were cultured with various concentrations of interleukin-2. Their ability to kill 51Cr-labelled NK and lymphokine-activated killer (LAK)-sensitive targets was assessed in the presence of rabbit blastocoelic fluid taken at day-12 of pregnancy (BF D-12). BF D-12 dramatically suppressed the killing activity of NK and LAK cells. This effect was observed on K562 (NK-sensitive targets), P815 cells (LAK-sensitive targets), and freshly isolated cells in rabbit trophoblastic cell preparation. Elimination of prostaglandin E2 (PGE2), but not transforming growth factor beta 2 (TGF beta 2) or 6 keto prostaglandin F1 alpha (6KPGF 1 alpha), by affinity chromatography, completely abolished BF biological activity. These findings clearly suggest that PGE2 in BF regulates the killing activity of NK and LAK cells, and that the semiallograft embryo plays an active role in its own protection. To our knowledge, it is the first demonstration that PGE2 from the embryo inhibits NK and LAK cell lytic activity.

TGF beta 2 in rabbit blastocoelic fluid regulates CD4 membrane expression: possible role in the success of gestation

PROBLEM

During pregnancy, major changes occur in the decidual cell population. One of these changes involves some phenotypical transformations of lymphocyte sub-populations. Since these variations might be due to the presence of the embryo, the current study was designed to investigate the implication of blastocoelic fluid (BF) in these changes and to determine the mechanism by which this phenomenon occurs.

METHOD

Lymphocytes isolated from human peripheral blood (PBL) were cultured for 72 h in RPMI-FCS 10% and with or without BF day 12 (BF d-12) or Concanavalin A (ConA). After 72 h, T cells were labelled with anti-CD4 antibodies and Quantum Simply Cellular microbeads were used as a standard to evaluate the antibody binding capacity (ABC).

RESULTS

Treatment of human PBL with BF d-12 decreases the percentage of CD4 and TCR positive cells, as compared to non-stimulated cells, but has no significant effect on CD2, CD3, and CD8 positive cells. It was also demonstrated, for the first time, that transforming growth factor beta-2 (TGF beta 2) in BF day 12 diminishes the percentage of CD4 positive cells by downregulating CD4 membrane expression on leucocytes.

CONCLUSION

These findings suggest that the embryo plays a role in its own protection. Furthermore, it is predicted that any tissue producing TGF beta 2, such as certain types of tumor, downregulates the immune response, thus allowing tumor growth.

In vitro characterization of purified human thymic dendritic cells infected with human immunodeficiency virus type 1

In the thymus, dendritic cells (DC) are functionally associated with thymocytes and are recognized to play a major role in the intrathymic differentiation of T cells. Several studies have previously investigated the role of DC during HIV-infection, but the status of thymic DC in HIV-1 pathogenesis remains unclear. In this study, we investigated the susceptibility of purified human thymic DC to HIV-1 infection in vitro. HIV-1 was not detected in cell-free supernatants collected from HIV-infected DC. However, these cultures were shown to transmit HIV-1 infection since coculture with permissive MT4 cells resulted in virus production. The exposure of DC in culture to HIV-1 was shown to promote severe DC morphological changes and killing. We also found that one or several heat labile soluble cytotoxic agents present in the HIV-1-infected DC supernatant mediated the killing of thymocytes. Our observations raise the possibility that (1) the HIV-1-induced DC killing, (2) the capacity of DC to transmit viral infection, and/or (3) the release of HIV-1-mediated cytotoxic agent(s) from DC may contribute to AIDS pathogenesis in vivo.

Characterization of the human and mouse Fli-1 promoter regions

Overexpression of the Fli-1 gene has been shown to be involved in retrovirus-induced mouse tumors. Cloning of the 5' flanking sequence of the mouse and human Fli-1 exon 1 was performed. At least two major transcription initiation sites were localized respectively at 143 and 114 nucleotides upstream of the previously defined mouse Fli-1 cDNA 5' end. The sequences flanking the CAP sites show good conservation between human and mouse (94%). The promoter region contains a potential TATA box lying 30 bp from one of the major identified CAP sites. Several conserved elements, such as GATA, EBS, GC rich, AP-2, AP-3 elements and a repetition of GA were observed next to the two major CAP sites. Furthermore, this latter was shown to form a H-DNA structure in vitro by S1 nuclease sensitivity experiments. The highly conserved 5' non-translated region of exon 1 is predicted to form a very stable hairpin structure which could regulate the Fli-1 expression at the post-transcriptional level. In Cas-Br-E-induced tumors, all the proviruses are found clustered within 35 nucleotides directly upstream the Fli-1 ATG start codon, thus deleting the hairpin structure from the transcript. Promoter activity was tested using the CAT reporter gene transfected in mouse and human erythroid cell lines. No promoter activity could be detected with various mouse Fli-1 promoter-CAT constructs containing 600 bp of the 5' flanking region, the complete exon 1, the 5' end of intron 1 and/or retroviral LTR sequence. Constructions of the human homologue containing nearly 1.5 kbp of Fli-1 5' flanking region was also inactive in transfected cells. These results suggest that multiple levels of regulation might control the Fli-1 expression.

Regulation of leukocyte interleukin 2 and interleukin 2 receptor gene expression by rabbit blastocoelic fluid

The mechanisms underlying the inhibition of lymphocyte proliferative response by rabbit blastocoelic fluid collected on day 12 of embryonic development were investigated. Treatment with blastocoelic fluid, even in the presence of concanavalin A, maintains lymphocytes in a quiescent state by preventing cell entry into the S phase of the cell cycle. Gene expression of interleukin 2 receptor is completely blocked by treatment with blastocoelic fluid as are the secretion and gene expression of interleukin 2. Addition of interleukin 2 to prestimulated interleukin 2 receptor positive lymphocytes failed to downregulate the expression of high-affinity interleukin 2 receptor and completely abolished the embryonic fluid-mediated inhibitory effect on [3H]thymidine incorporation. Taken together, these results suggest that embryonic fluid has differential inhibitory effects, depending on the activation state of the lymphocytes. Nevertheless, inhibition of interleukin 2 and interleukin 2 receptor expression by embryonic fluid restrains immune cell activity and therefore can be implicated in the survival of the fetal semi-allograft.

Retirement of senior physicians in rural Minnesota. Factors influencing physicians' plans to retire

The demand for physicians in rural Minnesota is likely to increase significantly over the next few years. Nearly 20% of all rural physicians in Minnesota are older than age 65. This paper reports the results of a survey of rural Minnesota physicians over age 60 on their current practices and their plans for retirement. Of the 33 physicians questioned, 25 (75%) currently had plans to retire and more than half of the 25 planned to retire in the next two years. Factors that these physicians perceived as important in determining their decisions to retire or continue practice are described, and implications for the delivery of health care in rural communities are discussed.

Mutagenic analysis of human immunodeficiency virus type 1 Vpr: role of a predicted N-terminal alpha-helical structure in Vpr nuclear localization and virion incorporation

The Vpr gene product of human immunodeficiency virus type 1 is a virion-associated protein that is important for efficient viral replication in nondividing cells such as macrophages. At the cellular level, Vpr is primarily localized in the nucleus when expressed in the absence of other viral proteins. Incorporation of Vpr into viral particles requires a determinant within the p6 domain of the Gag precursor polyprotein Pr55gag. In the present study, we have used site-directed mutagenesis to identify a domain(s) of Vpr involved in virion incorporation and nuclear localization. Truncations of the carboxyl (C)-terminal domain, rich in basic residues, resulted in a less stable Vpr protein and in the impairment of both virion incorporation and nuclear localization. However, introduction of individual substitution mutations in this region did not impair Vpr nuclear localization and virion incorporation, suggesting that this region is necessary for the stability and/or optimal protein conformation relevant to these Vpr functions. In contrast, the substitution mutations within the amino (N)-terminal region of Vpr that is predicted to adopt an alpha-helical structure (extending from amino acids 16 to 34) impaired both virion incorporation and nuclear localization, suggesting that this structure may play a pivotal role in modulating both of these biological properties. These results are in agreement with a recent study showing that the introduction of proline residues in this predicted alpha-helical region abolished Vpr virion incorporation, presumably by disrupting this secondary structure (S. Mahalingam, S. A. Khan, R. Murali, M. A. Jabbar, C. E. Monken, R. G. Collman, and A. Srinivasan, Proc. Natl. Acad. Sci. USA 92:3794-3798, 1995). Interestingly, our results show that two Vpr mutants harboring single amino acid substitutions (L to F at position 23 [L23F] and A30F) on the hydrophobic face of the predicted helix coded for relatively stable proteins that retained their ability to translocate to the nucleus but exhibited dramatic reduction in Vpr incorporation, suggesting that this hydrophobic face might mediate protein-protein interactions required for Vpr virion incorporation but not nuclear localization. Furthermore, a single mutation (E25K) located on the hydrophilic face of this predicted alpha-helical structure affected not only virion incorporation but also nuclear localization of Vpr. The differential impairment of Vpr nuclear localization and virion incorporation by mutations in the predicted N-terminal alpha-helical region suggests that this region of Vpr plays a role in both of these biological functions of Vpr.

Incorporation of Vpr into human immunodeficiency virus type 1: role of conserved regions within the P6 domain of Pr55gag

The 96-amino acid Vpr protein is the only virion-associated regulatory protein encoded by the human immunodeficiency virus type 1 (HIV-1). Vpr incorporation into the viral particle is most likely due to an interaction with a viral structural protein. Recent data have shown that DNA encoding for the p55 Gag precursor protein (Pr55gag) is the minimal viral genetic information necessary for Vpr incorporation. Other studies have suggested that the p6 portion of Pr55gag, which is unique to lentiviruses, is involved in Vpr incorporation. To investigate the mechanism of incorporation of Vpr into HIV-1 virions, COS-7 cells were cotransfected with ptrENV, an expression vector that encodes all of the HIV-1 regulatory proteins including Rev and Vpr, and different constructs of pIIIgagCAR, a rev-dependent Gag expression plasmid that encodes Pr55gag and the viral protease. Virions produced from gag constructs containing a premature p6 termination codon at positions Leu-1, Ser-17, Tyr-36, or Leu-44 lacked detectable Vpr. In contrast, gag constructs with double Pro-10-Pro-11 substitutions for Leu-10-Leu-11 or a premature termination codon at position Pro-49 of p6 were still able to incorporate Vpr, however, with lower efficiency than wild type. The mutations described in this study affected directly two short regions within the p6 domain, which are highly conserved among primate immunodeficiency viruses. Our results suggest that the conserved (P-T/S-A-P-P) and (L-X-S-L-F-G) motifs located near the N-terminus and C-terminus, respectively, of the p6 domain of Gag are critical for Vpr incorporation into HIV-1 virions.

Neuroleptic associated tardive dyskinesias in young people with psychoses

BACKGROUND

Apart from ageing, the factors associated with vulnerability to the emergence of tardive dyskinesia are poorly defined.

METHOD

Risk factors associated with the presence of a chronic choreic or dystonic disorder were assessed in a cross-sectional comparison of anamnestic and clinical data in a homogeneous group of 64 young psychotic patients (under 40 years of age) on chronic low to moderate doses of neuroleptics.

RESULTS

Dyskinetic subjects presented more indirect indicators of occult brain damage, such as a perinatal event or traumatic brain injuries in infancy and early childhood; neurological examination showed more anomalies in dyskinetic patients than in nondyskinetics, with a higher prevalence of facial release reflexes.

CONCLUSION

These data may support the hypothesis that occult acquired brain damage is important in the genesis of this 'drug-induced' disorder.