Syndecans serve as attachment receptors for human immunodeficiency virus type 1 on macrophages

Macrophages are thought to represent one of the first cell types in the body to be infected during the early stage of human immunodeficiency virus type 1 (HIV-1) transmission and represent a potential viral reservoir in vivo. Thus, an understanding of HIV-1 attachment to these cells is fundamental to the development of novel anti-HIV-1 therapies. Although one of the major targets of HIV-1 in vivo--CD4(+) T lymphocytes--express high CD4 levels, other major targets such as macrophages do not. We asked in this study whether this low CD4 level on macrophages is sufficient to support HIV-1 attachment to these cells or whether cell surface proteins other than CD4 are required for this process. We show that CD4 alone is not sufficient to support the initial adsorption of HIV-1 to macrophages. Importantly, we find that heparan sulfate proteoglycans (HSPGs) serve as the main class of attachment receptors for HIV-1 on macrophages. Most importantly, we demonstrate that a single family of HSPGs, the syndecans, efficiently mediates HIV-1 attachment and represents an abundant class of attachment receptors on macrophages.

Mapping of the rat glypican genes

The glypicans compose a family of glycosylphosphatidylinositol (GPI)-anchored heparan sulfate proteoglycans that play a role in the control of cell division and growth regulation. So far, six members (GPC1-6) of this family are known in vertebrates. The rat glypican gene 3 (Gpc3) was previously assigned to chromosome Xq36 (Shen et al., 1997). Using standard and radiation cell hybrids, we localized the five other rat glypican genes.

A 4-Mb BAC/PAC contig and complete genomic structure of the GPC5/GPC6 gene cluster on chromosome 13q32

The glypicans compose a family of glycosylphosphatidylinositol-anchored heparan sulfate proteoglycans that may play a role in the control of cell division and growth regulation. So far, six members (GPC1-6) of this family are known in vertebrates. We report the construction of a high-resolution 4 Mb sequence-ready BAC/PAC contig of the GPC5/GPC6 gene cluster on chromosome region 13q32. The contig indicates that, like the GPC3/GPC4 genes on Xq26, GPC5 and GPC6 are arranged in tandem array. Both GPC5 and GPC6 are very large genes, with sizes well over 1 Mb. With a size of approximately 2 Mb, GPC5 would be the second largest human gene identified to date. Comparison of the long range gene organisation on 13q and Xq, suggests that these chromosomes share several regions of homology. Mutations and deletions affecting GPC3 are associated with the Simpson-Golabi-Behmel overgrowth syndrome. Mutational analysis of GPC5 and GPC6 in 19 patients with somatic overgrowth failed to reveal pathologic mutations in either of these genes, but identified several coding region polymorphisms.

[The principle of precaution: its impact in medicine]

The principle of precaution first appeared about ten years ago as a new type of action and responsability in the environnemental domain. According to this priciple, immediate action must be taken to avoid serious environnemental consequences, without waiting for scientifically established proof of danger. Certain legalists are now recommending that this approach should be extended to the field of medicine. By recommending decisive action based on purely hypothetical risk, the principle of precaution goes well beyond classic preventive measures, which are introduced after identification and proof risk. This new approach is presented as an added safety precaution. Radical application of this concept could however lead to an irrational approach to health safety and constitute an obstacle to technical progress. Although the legal world has already adopted this new concept, it is important that the medical world contribute to evaluating this new standard.

Measurement of the midrapidity transverse energy distribution from square root of [(s)NN] = 130 GeV Au + Au collisions at RHIC

The first measurement of energy produced transverse to the beam direction at the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory is presented. The midrapidity transverse energy density per participating nucleon rises steadily with the number of participants, closely paralleling the rise in charged-particle density, such that <E(T)>/<N(ch)> remains relatively constant as a function of centrality. The energy density calculated via Bjorken's prescription for the 2% most central Au+Au collisions at square root[s(NN)] = 130 GeV is at least epsilon(Bj) = 4.6 GeV/fm(3), which is a factor of 1.6 larger than found at sqrt[s(NN)] = 17.2 GeV ( Pb+Pb at CERN).

Centrality dependence of charged particle multiplicity in Au-Au collisions at square root of (s)NN = 130 GeV

We present results for the charged-particle multiplicity distribution at midrapidity in Au-Au collisions at square root of [s(NN)] = 130 GeV measured with the PHENIX detector at RHIC. For the 5% most central collisions we find dN(ch)/d eta(vertical line eta = 0) = 622+/-1(stat)+/-41(syst). The results, analyzed as a function of centrality, show a steady rise of the particle density per participating nucleon with centrality.

Developmental roles of the glypicans

Glypicans are proteins with very characteristic structures that are substituted with heparan sulfate and that are linked to the cell surface via glycosylphosphatidylinositol. The modular structure of the glypicans has been highly conserved throughout evolution. Six glypicans have been identified so far in vertebrates. Mutations in Drosophila, humans and mice reveal a role for these cell surface molecules in the control of cell growth and differentiation. Their mechanism of action is not yet clear. Most likely, glypicans activate or determine the activity ranges of morphogens and growth factors such as FGFs, BMPs, Wnts, Hhs and IGFs.

Arcuate relaxing incisions with a 5.00-mm optical zone for the correction of high postcataract astigmatism

The purpose of this study was to investigate the efficacy and safety of arcuate cuts with a 5-mm optical zone to correct high postoperative astigmatism after extracapsular cataract extraction. We performed 5-mm optical zone arcuate cuts on 23 eyes of 23 patients with high postoperative astigmatism. Ophthalmic examination included uncorrected visual acuity (UCVA), best spectacle corrected visual acuity (BSCVA) and the amount of the refractive and keratometric cylinder before and 9 months after operation. Surgically induced refractive change was calculated in all cases. A significant reduction in astigmatism was achieved in all cases with minimal axis deviation. No case developed clinically significant irregular astigmatism. The mean magnitude of astigmatism of the surgically induced refractive change calculated from standard keratometry and refractive data was 3.73+/-0.72 and 3.70+/-0.77 dptr, respectively. The mean axis deviation calculated from the keratometric and refractive data was 1.18+/-2.33 and 1.32+/-3.62 degrees, respectively. At the last examination, 78.2% of the eyes had UCVA of 20/40 or better. No eye lost more than two lines of vision, 6 eyes lost one line, 2 eyes gained one and 1 eye gained two lines of BSCVA. The above data show that the 5-mm optical zone arcuate astigmatic keratotomy is an effective and safe method of correcting high postoperative astigmatism.

Characterization of syntenin, a syndecan-binding PDZ protein, as a component of cell adhesion sites and microfilaments

Syntenin is a PDZ protein that binds the cytoplasmic C-terminal FYA motif of the syndecans. Syntenin is widely expressed. In cell fractionation experiments, syntenin partitions between the cytosol and microsomes. Immunofluorescence microscopy localizes endogenous and epitope-tagged syntenin to cell adhesion sites, microfilaments, and the nucleus. Syntenin is composed of at least three domains. Both PDZ domains of syntenin are necessary to target reporter tags to the plasma membrane. The addition of a segment of 10 amino acids from the N-terminal domain of syntenin to these PDZ domains increases the localization of the tags to stress fibers and induces the formation of long, branching plasma membrane extensions. The addition of the complete N-terminal region, in contrast, reduces the localization of the tags to plasma membrane/adhesion sites and stress fibers, and reduces the morphotypical effects. Recombinant domains of syntenin with the highest plasma membrane localization display the lowest nuclear localization. Syndecan-1, E-cadherin, beta-catenin, and alpha-catenin colocalize with syntenin at cell-cell contacts in epithelial cells, and coimmunoprecipitate with syntenin from extracts of these cells. These results suggest a role for syntenin in the composition of adherens junctions and the regulation of plasma membrane dynamics, and imply a potential role for syntenin in nuclear processes.

Efficient male and female germline transmission of a human chromosomal vector in mice

A small accessory chromosome that was mitotically stable in human fibroblasts was transferred into the hprt(-) hamster cell line CH and developed as a human chromosomal vector (HCV) by the introduction of a selectable marker and the 3' end of an HPRT minigene preceded by a loxP sequence. This HCV is stably maintained in the hamster cell line. It consists mainly of alphoid sequences of human chromosome 20 and a fragment of human chromosome region 1p22, containing the tissue factor gene F3. The vector has an active centromere, and telomere sequences are lacking. By transfecting a plasmid containing the 5' end of HPRT and a Cre-encoding plasmid into the HCV(+) hamster cell line, the HPRT minigene was reconstituted by Cre-mediated recombination and expressed by the cells. The HCV was then transferred to male mouse R1-ES cells and it did segregate properly. Chimeras were generated containing the HCV as an independent chromosome in a proportion of the cells. Part of the male and female offspring of the chimeras did contain the HCV. The HCV(+) F1 animals harbored the extra chromosome in >80% of the cells. The HCV was present as an independent chromosome with an active centromere and the human F3 gene was expressed from the HCV in a human-tissue-specific manner. Both male and female F1 mice did transmit the HCV to F2 offspring as an independent chromosome with properties similar to the original vector. This modified small accessory chromosome, thus, shows the properties of a useful chromosomal vector: It segregates stably as an independent chromosome, sequences can be inserted in a controlled way and are expressed from the vector, and the HCV is transmitted through the male and female germline in mice.

Characterization of the gene encoding the 100-kDa form of human 2',5' oligoadenylate synthetase

The 2'-5' oligoadenylate synthetases (OAS) represent a family of interferon (IFN)-induced proteins implicated in the antiviral action of IFN. When activated by double-stranded (ds) RNA, these proteins polymerize ATP into 2'-5' linked oligomers with the general formula pppA(2'p5'A)n, n greater than or = 1. Three forms of human OAS have been described corresponding to proteins of 40/46, 69/71, and 100 kDa. These isoforms are encoded by three distinct genes clustered on chromosome 12 and exhibit differential constitutive and IFN-inducible expression. Here we describe the structural and functional analysis of the gene encoding the large form of human OAS. This gene has 16 exons with exon/intron boundaries that are conserved among the different isoforms of the human OAS family, reflecting the evolutionary link among them. The promoter region of the p100 gene is composed of multiple features conferring direct inducibility not only by IFNs but also by TNF and all-trans retinoic acid. In contrast, the induction of the p100 promoter by dsRNA is indirect and requires IFN type I production.

High molecular weight kininogen utilizes heparan sulfate proteoglycans for accumulation on endothelial cells

Kininogens, the high molecular weight precursor of vasoactive kinins, bind to a wide variety of cells in a specific, reversible, and saturable manner. The cell docking sites have been mapped to domains D3 and D5(H) of kininogens; however, the corresponding cellular acceptor sites are not fully established. To characterize the major cell binding sites for kininogens exposed by the endothelial cell line EA.hy926, we digested intact cells with trypsin and other proteases and found a time- and concentration-dependent loss of (125)I-labeled high molecular weight kininogen (H-kininogen) binding capacity (up to 82%), indicating that proteins are crucially involved in kininogen cell attachment. Cell surface digestion with heparinases similarly reduced kininogen binding capacity (up to 78%), and the combined action of heparinases and trypsin almost eliminated kininogen binding (up to 85%), suggesting that proteoglycans of the heparan sulfate type are intimately involved. Consistently, inhibitors such as p-nitrophenyl-beta-d-xylopyranoside and chlorate interfering with heparan sulfate proteoglycan biosynthesis reduced the total number of kininogen binding sites in a time- and concentration-dependent manner (up to 67%). In vitro binding studies demonstrated that biotinylated H-kininogen binds to heparan sulfate glycosaminoglycans via domains D3 and D5(H) and that the presence of Zn(2+) promotes this association. Cloning and over-expression of the major endothelial heparan sulfate-type proteoglycans syndecan-1, syndecan-2, syndecan-4, and glypican in HEK293t cells significantly increased total heparan sulfate at the cell surface and thus the number of kininogen binding sites (up to 3. 3-fold). This gain in kininogen binding capacity was completely abolished by treating transfected cells with heparinases. We conclude that heparan sulfate proteoglycans on the surface of endothelial cells provide a platform for the local accumulation of kininogens on the vascular lining. This accumulation may allow the circumscribed release of short-lived kinins from their precursor molecules in close proximity to their sites of action.

Stimulation-evoked increases in cytosolic [Ca(2+)] in mouse motor nerve terminals are limited by mitochondrial uptake and are temperature-dependent

Increases in cytosolic [Ca(2+)] evoked by trains of action potentials (20-100 Hz) were recorded from mouse and lizard motor nerve terminals filled with a low-affinity fluorescent indicator, Oregon Green BAPTA 5N. In mouse terminals at near-physiological temperatures (30-38 degrees C), trains of action potentials at 25-100 Hz elicited increases in cytosolic [Ca(2+)] that stabilized at plateau levels that increased with stimulation frequency. Depolarization of mitochondria with carbonylcyanide m-chlorophenylhydrazone (CCCP) or antimycin A1 caused cytosolic [Ca(2+)] to rise to much higher levels during stimulation. Thus, mitochondrial Ca(2+) uptake contributes importantly to limiting the rise of cytosolic [Ca(2+)] during repetitive stimulation. In mouse terminals, the stimulation-induced increase in cytosolic [Ca(2+)] was highly temperature-dependent over the range 18-38 degrees C, with greater increases at lower temperatures. At the lower temperatures, application of CCCP continued to depolarize mitochondria but produced a much smaller increase in the cytosolic [Ca(2+)] transient evoked by repetitive stimulation. This result suggests that the larger amplitude of the stimulation-induced cytosolic [Ca(2+)] transient at lower temperatures was attributable in part to reduced mitochondrial Ca(2+) uptake. In contrast, the stimulation-induced increases in cytosolic [Ca(2+)] measured in lizard motor terminals showed little or no temperature-dependence over the range 18-33 degrees C.

[Evolution of the member population of the French Academy of Medicine]

This survey includes all the 843 members of the French Academy of Medicine elected over the last 150 years (1850-1999). Various variables are analysed, namely the age at election, the length of life and the duration of membership. The main trends observed during the 20th century are the following. 1. A regular increase in the length of life (about 20 years), greater than in the overall French population. 2. A rising in the mean age at election until 1970 and a stabilisation afterwards. 3. A steady increase of the mean age of the population of members. Some projections are also developed for the next 25 years, based on various hypotheses: 1. A continuation of the current trends, taking only into account the foreseeable lengthening of life; this makes the difficulties observed during the last two decades becoming more acute; 2. The introduction of new rules such as a decrease in the mean age at election, or the settling of an upper age limit for regular membership (giving access to an Emeritus status). These measures induce a decrease of the mean age of the population, less or more intense. Some of the assumptions may also have a negative effect, by reducing the turnover rate.

Myc-enhanced expression of Cul1 promotes ubiquitin-dependent proteolysis and cell cycle progression

The c-Myc oncoprotein plays an important role in the growth and proliferation of normal and neoplastic cells. To execute these actions, c-Myc is thought to regulate functionally diverse sets of genes that directly govern cellular mass and progression through critical cell cycle transitions. Here, we provide several lines of evidence that c-Myc promotes ubiquitin-dependent proteolysis by directly activating expression of the Cul1 gene, encoding a critical component of the ubiquitin ligase SCF(SKP2). The cell cycle inhibitor p27(kip1) is a known target of the SCF(SKP2) complex, and Myc-induced Cul1 expression matched well with the kinetics of declining p27(kip1) protein. Enforced Cul1 expression or antisense neutralization of p27(kip1) was capable of overcoming the slow-growth phenotype of c-Myc null primary mouse embryonic fibroblasts (MEFs). In reconstitution assays, the addition of in vitro translated Cul1 protein alone was able to restore p27(kip1) ubiquitination and degradation in lysates derived from c-myc(-/-) MEFs or density-arrested human fibroblasts. These functional and biochemical data provide a direct link between c-Myc transcriptional regulation and ubiquitin-mediated proteolysis and together support the view that c-Myc promotes G(1) exit in part via Cul1-dependent ubiquitination and degradation of the CDK inhibitor, p27(kip1).

Syntenin-syndecan binding requires syndecan-synteny and the co-operation of both PDZ domains of syntenin

Syntenin is an adaptor-like molecule that binds to the cytoplasmic domains of all four vertebrate syndecans. Syntenin-syndecan binding involves the C-terminal part of syntenin that contains a tandem of PDZ domains. Here we provide evidence that each PDZ domain of syntenin can interact with a syndecan. Isolated or combined mutations of the carboxylate binding lysines in the inter-betaAbetaB loops and of the alphaB1 residues in either one or both the PDZ domains of syntenin all reduce syntenin-syndecan binding in yeast two-hybrid, blot-overlay, and surface plasmon resonance assays. PDZ2 mutations have more pronounced effects on binding than PDZ1 mutations, but complete abrogation of syntenin-syndecan binding requires the combination of both the lysine and the alphaB1 mutations in both the PDZ domains of syntenin. Isothermal calorimetric titration of syntenin with syndecan peptide reveals the presence of two binding sites in syntenin. Yet, unlike a tandem of two PDZ2 domains and a reconstituted PDZ1+PDZ2 tandem, a tandem of two PDZ1 domains and isolated PDZ1 or PDZ2 domains do not interact with syndecan bait. We conclude to a co-operative binding mode whereby neither of these two PDZ domains is sufficient by itself but where PDZ2 functions as a "major" or "high affinity" syndecan binding domain, and PDZ1 functions as an "accessory" or "low affinity" syndecan binding domain. The paired, but not the isolated PDZ domains of syntenin bind also strongly to the immobilized cytoplasmic domains of neurexin and B-class ephrins. By inference, these data suggest a model whereby recruitment of syntenin to membrane surfaces requires two compatible types of bait that are in "synteny" (occurring together in location) and engages both PDZ domains of syntenin. The synteny of compatible bait may result from the assemblies and co-assemblies of syndecans and other similarly suited partners in larger supramolecular complexes. In general, an intramolecular combination of PDZ domains that are weak, taken individually, would appear to be designed to detect rather than drive the formation of specific molecular assemblies.

Mutational analysis of the GPC3/GPC4 glypican gene cluster on Xq26 in patients with Simpson-Golabi-Behmel syndrome: identification of loss-of-function mutations in the GPC3 gene

Simpson-Golabi-Behmel syndrome (SGBS) is an X-linked syndrome characterized by pre- and postnatal overgrowth (gigantism), which clinically resembles the autosomal Beckwith-Wiedemann syndrome (BWS). Deletions and translocations involving the glypican-3 gene ( GPC3 ) have been shown to be associated with SGBS. Occasionally, these deletions also include the glypican-4 gene ( GPC4 ). Glypicans are heparan sulfate proteoglycans which have a role in the control of cell growth and cell division. We have examined the mutational status of the GPC3 and GPC4 genes in one patient with Perlman syndrome, three patients with overgrowth without syndrome diagnosis, ten unrelated SGBS-patients and 11 BWS patients. We identified one SGBS patient with a deletion of a GPC3 exon. Six SGBS patients showed point mutations in GPC3. One frameshift, three nonsense, and one splice mutation predict a loss-of-function of the glypican-3 protein. One missense mutation, W296R, changes an amino acid that is conserved in all glypicans identified so far. A GPC3 protein that reproduces this mutation is poorly processed and fails to increase the cell surface expression of heparan sulfate, suggesting that this missense mutation is also a loss-of-function mutation. In three SGBS patients and in all non-SGBS patients, no mutations could be identified. We found three single nucleotide polymorphisms in the GPC4 gene but no evidence for loss-of-function mutations in GPC4 associated with SGBS.

[Filiation in assisted reproduction with donor gametes]

Donor-assisted reproduction entails a definitive separation between biological and social filiation. In ovocyte donation, the dissociation remains partial, only genetic, because the pregnancy maintains a biological bond. On the contrary, in sperm donation, the break-off is complete. Should the circumstances of his/her conception be revealed to the child? Despite a long practice of artificial insemination by donor (AID) the issue is still a matter of controversy. The majority of couples undergoing AID prefer maintaining the secret. But this attitude goes against the right of the child to be aware of his/her origin

[Multi-recurrent cardiac arrest: when to discontinue cardiopulmonary resuscitation?]

A 52-year-old man developed an out-of-hospital cardiac arrest complicating a myocardial infarction. After prolonged cardiopulmonary resuscitation, he was admitted to an intensive care unit, where 25 episodes of cardiac arrests occurred within a few hours. Finally the outcome was favourable. This case raises the question of the duration a cardiopulmonary resuscitation in case of out-of-hospital and in-hospital cardiac arrest. The question is to determine how long resuscitation efforts must be prolonged after recurrent cardiac arrests.

Syndecan-1 and syndecan-4 can mediate the invasion of OpaHSPG-expressing Neisseria gonorrhoeae into epithelial cells

Neisseria gonorrhoeae (Ngo) expressing the outer membrane protein OpaHSPG can adhere to and invade epithelial cells via binding to heparan sulphate proteoglycan (HSPG) receptors. In this study, we have investigated the role of syndecan-1 and syndecan-4, two members of the HSPG family, in the uptake of Ngo by epithelial cells. When overexpressed in HeLa cells, both syndecans co-localize with adherent Ngo on the host cell surface. This overexpression of syndecan-1 and syndecan-4 leads to a three- and sevenfold increase in Ngo invasion respectively. In contrast, transfection with the syndecan-1 and syndecan-4 mutant constructs lacking the intracellular domain results in an abrogation of the invasion process, characteristic of a dominant-negative mode of action. A concomitant loss of the capacity to mediate Ngo uptake was also observed with syndecan-4 mutant constructs carrying lesions in the dimerization motif necessary for the binding of protein kinase C (PKC) and phosphatidylinositol 4,5-bisphosphate (PIP2), and mutants that are deficient in a C-terminal EFYA amino acid motif responsible for binding to syntenin or CASK. We conclude that syndecan-1 and syndecan-4 can both mediate Ngo uptake into epithelial cells, and that their intracellular domains play a crucial role in this process, perhaps by mediating signal transduction or anchorage to the cytoskeleton.

Gene-target recognition among members of the myc superfamily and implications for oncogenesis

Myc and Mad family proteins regulate multiple biological processes through their capacity to influence gene expression directly. Here we show that the basic regions of Myc and Mad proteins are not functionally equivalent in oncogenesis, have separable E-box-binding activities and engage both common and distinct gene targets. Our data support the view that the opposing biological actions of Myc and Mxi1 extend beyond reciprocal regulation of common gene targets. Identification of differentially regulated gene targets provides a framework for understanding the mechanism through which the Myc superfamily governs the growth, proliferation and survival of normal and neoplastic cells.

EMG and strength correlates of selected shoulder muscles during rotations of the glenohumeral joint

OBJECTIVE

To identify activation patterns of several muscles acting on the shoulder joint during isokinetic internal and external rotation.

DESIGN

Combined EMG and isokinetic strength analysis in healthy subjects.

BACKGROUND

EMG studies of the shoulder region revealed intricate muscular activation patterns during elevation of the arm but no parallel studies regarding pure rotations of the joint could be located.

METHODS

Fifteen (n=30 shoulders) young, asymptomatic male subjects participated in the study. Strength production during isokinetic concentric and eccentric internal and external rotations at 60 and 180 degrees /s was correlated with the EMG activity of the rotator cuff, biceps, deltoid and pectoralis major. Analysis of the smoothed EMG related to the timing of onset of the signal and to the normalized activity at the angle of the peak moment. Determination of the association between the EMG and the moment was based on strength ratios.

RESULTS

Findings indicated that for both types of rotations, the rotator cuff and biceps were active 0.092+/-0.038-0.215+/-0.045 s prior to the initiation of the actual movement and 0.112-0.034 s prior to onset of deltoid and pectoralis major activity. These differences were significant in all of the eight conditions (P<0.05). In terms of the strength ratios, strong association was found between electrical activity and moment production in the subscapularis and infraspinatus (r(2)=0.95 and 0. 72, respectively) at the low and high angular velocities.

CONCLUSIONS

Prior to actual rotation of the shoulder joint, normal recruitment of the rotator cuff and biceps is characterized by a non-specific presetting phase which is mainly directed at enhancing the joint 'stiffness' and hence its stability. Once movement is in progress, the EMG patterns of these muscles become movement specific and are correlated with the resultant moment.

RELEVANCE

Muscular dysfunction relating to delayed onset activity or altered activation patterns, due to pain, perturbed mechanics or disturbed neural activation have been implicated as concomitant factors in other joint associated pathologies. Through highlighting the role of the rotator cuff in shoulder joint rotations, this study lends further support to the argument that a parallel situation may prevail with respect to shoulder joint dysfunction. This could lead to the development of rehabilitation protocols aimed specifically at redressing such dysfunction.