Polymères thiocarboxyliques, 1. Synthèse et étude de la polymérisation radicalaire de monomères dithiocarboxyliques

The syntheses and free-radical polymerizations of methyl and carboxymethyl 4-vinyldithiobenzoates are described as well as various copolymers. Copolymerisation parameters were determined for the copolymerizations of the methyl dithioester with styrene and with methyl methacrylate.     

Morphology of Marburg virus NP-RNA

When Marburg virus (MBGV) nucleoprotein (NP) is expressed in insect cells, it binds to cellular RNA and forms NP-RNA complexes such as insect cell-expressed nucleoproteins from other nonsegmented negative-strand RNA viruses. Recombinant MBGV NP-RNA forms loose coils that resemble rabies virus N-RNA. MBGV NP monomers are rods that are spaced along the coil similar to the nucleoprotein monomers of the rabies virus N-RNA. High salt treatment induces tight coiling of the MBGV NP-RNA, again a characteristic observed for other nonsegmented negative-strand virus N-RNAs. Electron microscopy of fixed Marburg virus particles shows that the viral nucleocapsid has a smaller diameter than the free, recombinant NP-RNA. This difference in helical parameters could be caused by the interaction of other viral proteins with the NP-RNA. A similar but opposite phenomenon is observed for rhabdovirus nucleocapsids that are condensed by the viral matrix protein upon which they acquire a larger diameter. Finally, there appears to be an extensive and regular protein scaffold between the viral nucleocapsid and the membrane that seems not to exist in the other negative-strand RNA viruses.     

Improving HIV surveillance in Victoria: the role of the "detuned" enzyme immunoassay

Between 1999 and 2000, new diagnoses of HIV in Victoria (Australia) rose by 41%, from 140 to 197. In this time period, sera from new HIV diagnoses were tested using the Organon Teknika "detuned" enzyme immunoassay (EIA). We compared the results of the detuned EIA with incident infections defined by surveillance (on the basis of a previous negative or indeterminate HIV test and/or a seroconversion illness within the 12 months preceding HIV diagnosis). Of 317 specimens, 97 (31%) incident infections and 114 (36%) recent infections were detected using surveillance and detuned EIA, respectively. The detuned assay misclassified 11 cases with AIDS and 2 cases with CD4 counts < or = 200 micro3 (probable long-standing infections) as recent infections and was unable to identify 31 (32%) of 97 cases previously classified as incident cases by surveillance. The assay detected an extra 35 recent infections that were previously classified as nonincident by surveillance. By combining the detuned assay and surveillance, 132 (42%) incident infections were identified from 317 specimens, 36% more than surveillance alone. We recommend that a detuned assay or similar test become part of the routine strategy to identify incident infections in Victoria. Incident infections provide important information for targeting prevention strategies and the opportunity to interrupt ongoing viral transmission.     

The tyrosine-based YXXØ targeting motif of murine leukemia virus envelope glycoprotein affects pathogenesis

Retroviruses, such as human and simian immunodeficiency viruses (HIV and SIV), and murine leukemia viruses (MuLV), harbor a tyrosine-based motif in the intracytoplasmic domain of their envelope glycoprotein. This motif can act as an endocytosis signal or as a targeting signal, restricting viral budding at specific cell surface membrane domains. In the present study, proviral DNA of the ecotropic Cas-Br-E strain of MuLV was modified by substitution or deletion of the critical tyrosine residue. Mutant viruses lost basolateral targeting in polarized MDCK epithelial cells while expression level of the glycoprotein at the cell surface was not affected. This suggests that the tyrosine-based motif in MuLV does not act as an endocytosis signal. Only a small delay in the appearance of disease was observed in inoculated mice. In contrast, a striking change in the pathology was observed with enlarged thymus and lymph nodes in animals inoculated with mutant viruses.     

Fibrillar beta-amyloid peptide Aβ1–40 activates microglial proliferation via stimulating TNF-α release and H2O2 derived from NADPH oxidase: a cell culture study

Background  

Alzheimer's disease is characterized by the accumulation of neuritic plaques, containing activated microglia and β-amyloid peptides (Aβ). Fibrillar Aβ can activate microglia, resulting in production of toxic and inflammatory mediators like hydrogen peroxide, nitric oxide, and cytokines. We have recently found that microglial proliferation is regulated by hydrogen peroxide derived from NADPH oxidase. Thus, in this study, we investigated whether Aβ can stimulate microglial proliferation and cytokine production via activation of NADPH oxidase to produce hydrogen peroxide.     

Clinical information technology in hospitals: a comparison between the state of Iowa and two provinces in Canada

Despite the growing interest in adopting information technology (IT) in healthcare, the degree of technology sophistication varies among healthcare organizations. Changes in the health care sector and continuous pressure to improve the quality of care have driven the evolution of IT in hospitals. This paper provides an overview of clinical IT sophistication in a sample of U.S. hospitals, and compares clinical IT capacities in this sample with a sample of Canadian hospitals. The instrument used for the comparison measures three clinical dimensions of IT sophistication: functional sophistication, technological sophistication and integration level. Clinical areas that were considered include patient management, patient care activities and clinical support activities. The comparison between hospitals in Iowa and Canada shows differences in clinical IT sophistication between the two settings. Hospitals in Iowa appear to have more technologies but fewer computerized processes and integration of patient management activities. Technological sophistication however, was low in both samples. Our findings confirm the construct validity of the measurement instrument and show initial evidence of its generalizability. More initiatives using the instrument would lead to enhancement in IT assessment tools that can be used for evaluation of IT in relation to patient management and quality outcomes.     

DNA probe array for the simultaneous identification of herpesviruses, enteroviruses, and flaviviruses

Viral infections of the central nervous system (CNS) are caused by a variety of viruses, namely, herpesviruses, enteroviruses, and flaviviruses. The similar clinical signs provoked by these viruses make the diagnosis difficult. We report on the simultaneous detection of these major CNS pathogens using amplification by PCR and detection of amplified products using DNA microarray technology. Consensus primers were used for the amplification of all members of each genus. Sequences specific for the identification of each virus species were selected from the sequence alignments of each target gene and were synthesized on a high-density microarray. The amplified products were pooled, labeled, and cleaved, followed by hybridization on a single array. This method was successfully used to identify herpesviruses, namely, herpes simplex virus type 1 (HSV-1), HSV-2, and cytomegalovirus; all serotypes of human enteroviruses; and five flaviviruses (West Nile virus, dengue viruses, and Langat virus). This approach, which used highly conserved consensus primers for amplification and specific sequences for identification, would be extremely useful for the detection of variants and would probably help solve some unexplained cases of encephalitis. The analytical sensitivity of the method was shown to be 500 genome equivalents ml(-1) for HSV-1, 0.3 50% tissue culture infectious doses (TCID50s) ml(-1) for the enterovirus coxsackievirus A9, and 200 TCID50s ml(-1) for West Nile virus. The clinical sensitivity of this method must now be evaluated.     

Nociceptive stimulation activates locus coeruleus neurones projecting to the somatosensory thalamus in the rat

In the thalamus, noradrenergic output from the pontine nucleus locus coeruleus (LC) may actively shape the response properties of various sensory networks en route to the cortex. Little is known, however, about the involvement of ascending noradrenergic innervation of the somatosensory thalamus in the processing of nociceptive information. To address this question, we combined the study of Fos expression upon nociceptive tooth pulp stimulation in the anaesthetized rat, with the detection of retrogradely traced neurones from the somatosensory thalamus. Cell bodies labelled retrogradely from the left thalamus were observed on both sides of the LC, with an ipsilateral predominance ( n = 8). Electrical stimulation of the right incisor pulp ( n = 4) provoked a significantly stronger Fos expression (around twice) than sham surgery ( n = 4), in both the ipsi- and contralateral LC. Significantly larger numbers of double labelled neurones were counted in the LC of tooth-pulp-stimulated animals (representing around 30% of retrogradely labelled cells in LC) than in the LC of sham animals. They were found bilaterally, but with a clear, significant, ipsilateral (i.e. left) predominance. The present data offer an anatomical framework to understand how the LC is involved in the sensory processing of nociceptive information in the thalamus. For the first time, it is shown that nociceptive stimulation activates LC neurones projecting to the somatosensory thalamus. This suggests a new role for LC in modulating nociception within the thalamus.     

The volume-activated chloride current in endothelial cells from bovine pulmonary artery is not modulated by phosphorylation

We employed the patch-clamp technique to investigate the effects of various phosphorylation pathways on activation and modulation of volume-activated Cl- currents (I _Cl,vol) in cultured endothelial cells from bovine pulmonary arteries (CPAE cells). Half-maximal activation ofI _Cl,vol occurred at a hypotonicity of 27.5 ± 1.2%. Run-down of the current upon repetitive activation was less than 15% within 60 min. Stimulation of protein kinase C (PKC) by phorbol-12-myristate-13-acetate (PMA) or by (–)-indolactam did not affectI _Cl,vol. Down regulation of PKC activity by a 24-h preincubation of the cells with 0.2 mol/l PMA, or its inhibition by loading the cells with the specific inhibitory 19–31 pseudosubstrate peptide, did not influenceI _Cl,vol. Trifluoperazine and tamoxifen fully blockedI _cCl,vol with concentrations required for half-maximal inhibition of 3.0 and 2.4 mol/1 respectively. This inhibitory effect is probably not mediated by the calmodulin-antagonistic action of these compounds, because it occurs at free intracellular [Ca²⁺] of 50 nmol/l, which are below the threshold for calmodulin activation. The tyrosine kinase inhibitor herbimycin A (1 ol/1) and genistein (100 ol/1) did not affectI _Cl,vol Exposing CPAE cells to lysophosphatidic acid (1mol/1), an activator of p42 MAPkinase and the focal adhesion kinase p125^FAK in endothelial cells, neither evoked a Cl^– current nor affectedI _Cl,vol Neither wortmannin (10 mol/1), an inhibitor of MAP kinases and of PI-3 kinase, nor rapamycin (0.1 mmol/1), which interferes with the p70S6 kinase pathway, affectedI _Cl,vol Exposure of CPAE cells to heat or Na-arsenite, both activators of a recently discovered stress-activated tyrosine phosphorylation pathway, neither activated a current nor affected the hypotonic solution-induced Cl^– current. We conclude that none of the studied phosphorylation pathways is essential for the activation of the Cl^– current induced by hypotonicity.     

Host striatal projections into fetal ventral mesencephalic tissue grafted to the striatum of immature or adult rat

We have previously reported that few striatal axons from adult host brain innervate intrastriatal grafts of fetal ventral mesencephalic tissue. To see whether the immature rat brain would favor striatal innervation of the graft, unilateral implantation of fetal ventral mesencephalic tissue was carried out at 7 (P7), 14 (P14), or 60 (adults) days of age in neonatally dopamine- (DA)-lesioned and nonlesioned rats. Immunocytochemistry for tyrosine hydroxylase (TH), and/or dopamine- and adenosine 3′,5′-monophosphate-regulated phosphoprotein-32 (DARPP-32) was performed 2–6 months later. In the great majority of immature and in all adult recipients, the resulting graft consisted of a distinct intrastriatal mass of tissue surrounded by the host parenchyma. Most TH-immunopositive neurons were found within the confines of such grafts, although some were lying at short distances into the host striatal tissue, particularly in immature recipients. In a few immature recipients, there was, however, extensive intermingling of TH-positive neurons with the adjacent host brain tissue. In all recipients grafted at P7, P14, or as adults, the distinct, intra-parenchymal grafts contained moderate numbers of DARPP-32-positive processes, mainly at their periphery. These results indicate that the limited capacity of host striatal neurons to grow axons into transplanted fetal ventral mesencephalic tissue is not markedly different in young versus adult rats. A better integration of the ventral mesencephalic graft into the striatal circuitry of immature — as opposed to adult — recipients should therefore rely more on the higher tendency of DA neurons to become located into the host tissue following transplantation in young rats.