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T Greenland

Publications and source records attributed to T Greenland.

At least 37 records · Page 2Linked to original sources
PubMed1998

Visna-maedi virus induces interleukin-8 in sheep alveolar macrophages through a tyrosine-kinase signaling pathway.

The mechanisms leading to the severe lung damage seen in some sheep naturally infected with the visna-maedi virus, and to pulmonary lesions in other lentiviral diseases, appear to involve the recruitment of large numbers of uninfected inflammatory cells. Only a few alveolar macrophages from experimentally infected lambs express virus, but high levels of interleukin (IL)-8 mRNA are present in the macrophage population. In vitro infection with visna-maedi virus at low multiplicity of alveolar macrophages from uninfected sheep also strongly induced the expression of IL-8 mRNA and the accumulation of IL-8 in the extracellular medium. An initial peak of IL-8 mRNA expression at 3 or 6 h after infection was followed by a fall, then a more persistent expression lasting at least 48 h after infection. The early peak was accompanied by expression of mRNA for IL-1beta, and a possible rise in tumor necrosis factor alpha (TNFalpha) mRNA, although this was frequently elevated in uninfected ovine alveolar macrophages. Interestingly, these events occurred identically in cells treated with non-infectious heat-treated virus, suggesting that interaction between viral components and cellular membrane receptors could suffice for both early and late IL-8 induction. The level of IL-8 mRNA induced by treatment with live or inactivated virus could be severely reduced by pretreatment of the macrophages with genistein but not with staurosporine, suggesting the involvement of a tyrosine-kinase signaling pathway. The early induction of IL-1beta and possibly of TNFalpha may explain the occurrence of a later persistent expression of IL-8 mRNA through an autocrine mechanism.

Animals↗
PubMed1997

Distribution of the synergistic haemolysin genes hld and slush with respect to agr in human staphylococci.

Several staphylococcal species express a synergistic activity which potentiates hemolysis by beta-hemolysin. In Staphylococcus aureus, this activity is mediated by the delta-hemolysin, coded by the hld gene within the agr locus. In S. lugdunensis, the equivalent activity results from the production of 3 small peptides coded by an operon named slush, distinct from hld and located outside the agr region. We examined 15 clinically relevant staphylococcal species for the presence of hld, slush and agr by specific hybridisation. All species contained a recognizable agr-related locus. Three species never produced synergistic haemolysis and contained neither hld nor slush. Of the 12 producer strains, 5 contained hld, apparently within the agr region, 4 contained slush and one (S. caprae) contained both. Two other producer species (S. hominis and S. simulans) hybridised to neither probe.

Bacterial Proteins↗
PubMed1997

Genomic heterogeneity of small ruminant lentiviruses: existence of heterogeneous populations in sheep and of the same lentiviral genotypes in sheep and goats.

We have recently shown that French small ruminant lentiviruses (SRLV) from sheep are more similar to Caprine Arthritis Encephalitis Virus (CAEV) than to visna maedi virus (VMV) in a conserved region of the pol gene. To extend these results, we have examined sequences from a variable region of the env gene in French SRLV. We found that they were nearly equally distant from both CAEV and VMV strains, suggesting a considerable divergence since the initial introduction of the virus. Analysis of separate clones from individual animals showed that some carry a population of variant viruses. The study of further pol gene sequences from both goats and sheep suggests that viral variants show little or no host species specificity. A phylogenetic tree of pol gene sequences confirmed the presence of a novel genotype of SRLV in France.

Amino Acid Sequence↗
PubMed1997

Presence of a unique parainfluenza virus 3 strain identified by RT-PCR in visna-maedi virus infected sheep.

The presence in farm sheep of a paramyxovirus closely related to parainfluenza virus type 3 (Pi3) from humans or cattle was confirmed using RT-PCR on RNA samples from lung cells from slaughtered animals. Sequencing and restriction enzyme patterns of the amplified fragment of the F gene confirms the distinctness of the isolate, and suitable PCR primers allow specific detection of the ovine virus. A study of the incidence of ovine Pi3 in samples from sheep with or without distinctive histopathological signs of maedi shows that it is uncommon in aged sheep with overt lentiviral disease, but it occurs at moderate frequency in lambs and may, in the presence of visna-maedi virus, contribute to early lesion formation.

Abattoirs↗
PubMed1997

Synergistic hemolytic activity of Staphylococcus lugdunensis is mediated by three peptides encoded by a non-agr genetic locus.

Some strains of the coagulase-negative Staphylococcus lugdunensis produce a synergistic hemolytic activity (SLUSH), phenotypically similar to the delta-hemolysin of S. aureus. Reverse-phase high-pressure liquid chromatography of supernatants from S. lugdunensis 307 yielded three late-eluting peaks of 3.5 kDa with synergistic hemolytic activity. A degenerate oligonucleotide probe was designed from partial amino acid sequences of the 23-amino-acid (aa) tryptic fragments from one of the three peaks and hybridized to a single 2.8-kb HindIII chromosomal fragment. The relevant portion of this fragment was cloned by PCR, and sequencing showed the presence of three related open reading frames (ORFs), SLUSH-A, SLUSH-B, and SLUSH-C, preceded by an unrelated short potentially coding sequence (ORF-X), cotranscribed on a polycistronic 838-nucleotide mRNA. The amino acid sequences of the peptides from the three peaks align perfectly with the predicted sequences from the three SLUSH ORFs (peak I = SLUSH-B; peak II = SLUSH-C; peak III = SLUSH-A). These three peptides are closely related (amino acid homology, >76%) and do not show significant homology to S. aureus delta-hemolysin but do resemble a Salmonella typhimurium invasin and the "gonococcal growth inhibitor," a bacteriocin secreted by Staphylococcus haemolyticus. The predicted ORF-X gene product is a 24-aa peptide with no homology to the SLUSH peptides.

Amino Acid Sequence↗
PubMed1996

Nucleic acid sequence and affiliation of pLUG10, a novel cadmium resistance plasmid from Staphylococcus lugdunensis.

Tolerance of Staphylococcus lugdunensis to relatively high levels of cadmium is mediated by a 3117-bp plasmid, pLUG10. Sequencing reveals three major open reading frames (ORFs) in a single orientation. One ORF encompasses the origin of replication and its predicted product (RepL: 350 amino acids (aa)) shows 70% homology in its deduced aa sequence with Rep proteins of the pT181 family. A lagging strand conversion signal (palA) very similar to that of class 1 plasmids is present outside the rep-ori locus. The other two ORFs of 209 and 116 aa show 92.5% homology between their deduced aa sequences and the CadB and CadX peptides from the pOX6 plasmid of Staphylococcus aureus. The CadX-like peptide is 40% homologous to the S. aureus CadC product. Deletion of the C-terminal cadX gene by restriction enzyme digestion or frame-shift inactivation of the cadB gene reduced, but did not completely abolish, cadmium resistance. The two gene products may act cooperatively to confer cadmium resistance in S. lugdunensis.

Amino Acid Sequence↗
PubMed1996

Flow cytometric analysis of goat milk lymphocytes: subpopulations and adhesion molecule expression.

Cytometric analysis of cells in milk from healthy goats was achieved after elimination of interfering signals from debris and dead cells by irreversible staining with ethidium monoazide. Some 61% of milk lymphocytes are CD8+ T cells, 17% are CD4+ and about 20% of these express class II antigens: less than 4% are B cells. Compared with blood, the CD4/CD8 ratio was inverted and fewer lymphocytes expressed CD4SR or L-selectin. Monoclonal antibodies to ovine integrins recognised the caprine alpha 4 chain on most lymphocytes from milk or blood, while beta 1 was more frequent on milk cells.

Animals↗
PubMed1996

Histogenesis of the pulmonary lesions in the course of visna maedi virus-induced pneumonia.

The major characteristic lesion observed following spontaneous infection of sheep by the prototype lentivirus, maedi-visna virus (MVV), is a lymphocytic intestitial pneumonia. Similar lesions may be observed with variable frequency following infection of other species by pathogenic lentiviruses, for example in children infected by HIV-1. Further, lentivirus-induced lesions involving organs other than the lungs frequently involve a comparable cellular infiltration. The cellular composition of bronchoalveolar lavage specimens from naturally- or experimentally-infected sheep has been examined with a view to describing the pathological progression of lentivirus-induced lung lesions. The naturally-infected sheep presented advanced lesions typical of 'maedi', while the experimentally-infected newborn lambs permitted the study of early lesions which we refer to as 'pre-maedi'. In both cases there was a considerable infiltration of lymphocytes, predominantly CD8+ in maedi, but with nearly equal numbers of CD4+ cells in pre-maedi. A large proportion of the alveolar lymphocytes in spontaneous maedi, but not in experimentally-infected lambs, express high levels of MHC class II antigen, suggesting an activated phenotype. Activated macrophages, the chief target cells for MVV infection, are also present at this advanced stage of the disease suggesting the involvement of mediators such as IL-8 in the cellular interactions leading to the localization of particular lymphocyte sub-populations in the pulmonary parenchyma during lentiviral disease.

Animals↗
PubMed1995

Ovine aortic smooth muscle cells allow the replication of visna-maedi virus in vitro.

Visna-maedi virus induces in sheep an interstitial lung disease characterised by an accumulation of smooth muscle cells (SMC) or myomatosis. Infection by HIV-1 has been recently associated with disorders of the vessel-derived cells: primary pulmonary hypertension, coronary artery disease and smooth muscle tumors in humans. We hypothesized that, besides their regular targets (i.e. macrophages and lymphocytes), lentiviruses could infect smooth muscle cells. Smooth muscle cell cultures derived from ovine aorta were infected with visna-maedi virus strain K1514. The cultured cells were smooth muscle cells as demonstrated by their antigenic expression of alpha-actin and vimentin. The lentiviral infection of the smooth muscle cells was demonstrated by a typical cytopathic effect (syncytia), the expression of virus specific antigens, and the presence of genomic RNA detected by Northern blot analysis and RT PCR. The detection of a reverse transcriptase activity, the presence of viral RNA in supernatants of infected smooth muscle cells detected by RT PCR and their ability to infect ovine permissive fibroblasts demonstrated a productive infection. The ability of smooth muscle cells to be infected by lentiviruses may participate in the pathogenesis of the tissue damage associated with the lentiviruses such as myomatosis in sheep and vascular disease in humans.

Animals↗
PubMed1995

Genomic heterogeneity in the pol region of ovine lentiviruses obtained from bronchoalveolar cells of infected sheep from France.

In order to determine the genomic heterogeneity of ovine lentiviruses, we analysed eight isolates from naturally infected sheep from one geographical region of France. A 475 nt fragment in the region of the pol gene coding for reverse transcriptase was amplified by RT-PCR from RNA directly extracted from uncultured bronchoalveolar lavage cells. The resulting PCR fragments were analysed by restriction enzyme digestion, cloned in a TA vector and sequenced. Restriction enzyme analysis showed distinct patterns from the eight isolates, and sequencing showed them to be closely related in both nucleotide (2.3-8.1% variation) and deduced amino acid (0-6.2% variation) sequences. Their amino acid sequences differed from that of visna-maedi virus complete viral genome sequence K1514 by 12.5-15.3%, but from that of caprine arthritis encephalitis virus (CAEV) viral genome sequence Co by only 4.2-6.9%. Phylogenetic analysis showed that the French isolates form a group related to CAEV Co and distant from previously reported ovine lentivirus sequences from different origins.

Amino Acid Sequence↗
PubMed1995

Catheter-related bacteremia associated with coagulase-positive Staphylococcus intermedius.

We report a case of catheter-related bacteremia in a 63-year-old patient caused by Staphylococcus intermedius. Clinical resolution of the infection was obtained after removal of the intravenous device and antibiotic treatment. This observation emphasizes the risk of confusion between S. intermedius and Staphylococcus aureus if only a coagulase test is done.

Bacteremia↗
PubMed1995

Infection of lactating goats by mammary instillation of cell-borne caprine arthritis-encephalitis virus.

The possibility of transmission of caprine arthritis-encephalitis virus between lactating goats by the transfer of infected cells during milking has been examined experimentally. Four virus-free Saanen goats were infected, two in full lactation and two during the drying off period, by instillation of infected allogeneic cells into the milk canal of one-half of the udder. All four goats became infected, as shown by the isolation of virus from peripheral blood monocytes, seroconversion, and presence of typical lesions in the mammary gland. The virus was rapidly and constantly demonstrable in cells from the mammary secretions of the dry goats, but less regularly detected from milk cells from the lactating goats. Virus was more frequently isolated when milk SCC were elevated. Virus was present as often in secretions from the uninoculated half of the udder as the inoculated half. Dry goats seroconverted progressively, although antibody concentrations remained low; the lactating goats developed weak, positive Western blots in the late phase of lactation but only gave positive ELISA titers after drying off and artificial reinduction of lactation. At necropsy, lesions typical of the virus were observed in the mammary tissues of all four goats, and three had arthritis of the carpi.

Animals↗
PubMed1994

Sequencing of the ovine interleukin-8-encoding cDNA using the polymerase chain reaction.

The nucleotide (nt) sequence encoding the ovine homologue of interleukin-8 (IL-8) was determined. The mRNA is 1494-nt long with an ORF of 101 codons. The long 3' non-coding element contains several ATTTA repeats implicated in the swift turnover of other chemokine mRNAs. The encoded protein of 11 kDa before processing, and 9 kDa as mature protein, contains the Cys-Xaa-Cys motif common to alpha-chemokines, and has conserved amino acids (aa) at positions identified as receptor contact sites for IL-8. Identities with other published IL-8 aa sequences are: dog, 91%; pig, 87%; rabbit, 84%; human, 78%; guinea pig, 69%. A 49% aa identity is also found with a chicken embryo fibroblast protein.

Amino Acid Sequence↗
PubMed1994

Coagulase deficiency in clinical isolates of Staphylococcus aureus involves both transcriptional and post-transcriptional defects.

The molecular basis of the non-expression of coagulase was investigated for 14 coagulase-negative isolates of Staphylococcus aureus obtained from different clinical samples. These isolates had typical S. aureus characteristics such as production of clumping factor, DNAase and protein A, but, with one exception, failed to produce detectable amounts of alpha-haemolysin. All 14 strains had DNA homologous to the coagulase gene (coa), but a coa-specific transcript was found in only seven of them. alpha-Haemolysin mRNA was detected in only eight strains without direct correlation to coa-mRNA expression. Thus, coagulase and alpha-haemolysin deficiencies in S. aureus may involve either transcriptional or post-transcriptional alterations although additional regulatory factors may influence the expression of both genes.

Bacterial Toxins↗
PubMed1994

Coagulase expression in Staphylococcus aureus is positively and negatively modulated by an agr-dependent mechanism.

Expression of staphylocoagulase by agr+ Staphylococcus aureus depends on the growth phase, being maximal during exponential growth and decreasing sharply postexponentially, while an agr-deleted strain continuously expresses an intermediate level of coagulase. Therefore, coagulase expression appears to be both positively and negatively modulated by an agr-dependent mechanism.

Coagulase↗