Search PubMed⌕ Search

Biomedical subjects

T Greenland

Publications and source records attributed to T Greenland.

At least 55 records · Page 3Linked to original sources
PubMed1994

Clotting activity in Staphylococcus schleiferi subspecies from human patients.

Staphylococcus schleiferi subsp. schleiferi is a coagulase-negative staphylococcus, usually present as a contaminant in human specimens. A near relative, S. schleiferi subsp. coagulans, possesses coagulase activity but has not been reported from humans. We here describe three isolates of pseudocoagulase-positive S. schleiferi subsp. schleiferi and one isolate of S. schleiferi subsp. coagulans from human patients. The pseudocoagulase from the S. schleiferi subsp. schleiferi isolates differs from S. aureus staphylocoagulase by being sensitive to a combination of protease inhibitors (aprotinin, N-ethylmaleimide, and heparin). These isolates could all easily be confused with S. aureus in a typical clinical laboratory, since they all possess a heat-stable DNase and promote clotting formation. Moreover, S. schleiferi subsp. coagulans produces protein A, and S. schleiferi subsp. schleiferi expresses a clumping factor (fibrinogen affinity factor). Southern blot hybridization with an S. aureus coa-specific probe revealed no sequence related to the coa gene in any of the S. schleiferi isolates, and their riboprobe profiles and biochemical characteristics were typical of S. schleiferi subspecies, not of S. aureus. This study demonstrates that both subspecies of S. schleiferi can promote clotting of rabbit plasma in the standard tube test for coagulase.

Animals↗
PubMed1994

From granuloma to fibrosis in interstitial lung diseases: molecular and cellular interactions.

Granuloma is a feature of many chronic interstitial lung diseases, and may serve as a focus for subsequent fibrosis. Granulomas are composed of structured masses of cells of the macrophage lineage, which adopt an epithelioid aspect, interspersed with lymphocytes. They are formed around local centres of irritation. During their resolution, fibroblasts congregate around the structures and may penetrate the interior. In many cases, granulomas can disappear without leaving lasting traces. However, especially when damage has occurred to the surrounding tissue, permanent scarring and fibrosis may occur. Both types of cell present in the granuloma are capable of secreting a number of factors influencing the accumulation and proliferation of fibroblasts, both positively and negatively. The possible roles played by the different factors and, especially, interactions between them are discussed in the light of fibrosis formation. Possible therapeutic interventions are summarized.

Cytokines↗
PubMed1994

Lentivirus-induced interstitial lung disease: pulmonary pathology in sheep naturally infected by the visna-maedi virus.

Visna-maedi virus is a lentivirus that causes a chronic disease in sheep affecting, among other organs, the lungs. Interstitial pneumonitis is similar to that in man associated with the infection by the human immunodeficiency virus type-1. We have compared the pathological features of lungs of sheep naturally infected with visna-maedi virus with the results obtained from bronchoalveolar lavage and virus isolation. Semi-quantitative grading of the lesions was performed on 147 sheep lungs obtained from the slaughterhouse. Seventy-seven were macroscopically and histologically normal, 39 had typical lesions of interstitial lung disease (maedi), and 13 had minor lesions of the same type. Eighteen of the affected lungs were heavily infested with parasites. Of these parasite-infected lungs, 9 showed typical maedi lesions and 4 showed minor lesions; parasite infection had no obvious effect on the development of maedi. In keeping with pathological findings, bronchoalveolar lavage disclosed an alveolitis process in the maedi lungs with increased macrophage, lymphocyte and neutrophil numbers. Cytopathic virus was detected from alveolar macrophage coculture with fibroblasts more often from maedi lungs (10/12) than from normal lungs (9/39). Electron microscopy of bronchoalveolar lavage cocultures revealed typical lentiviral particles. Animals with minor lesions may be at an early stage of the disease.

Animals↗
PubMed1993

Role of bacteriophages in genomic variability of related coagulase-negative staphylococci.

DNA analysis using pulsed-field gel electrophoresis (PFGE) has emerged as one of the most sensitive epidemiological tools for the characterization of coagulase-negative staphylococci (CNST). The significance of some minor differences observed between the DNA restriction pulsed patterns of two CNST strains are difficult to interpret since they can theoretically be due to minor chromosomal rearrangements or to phage DNA integration. The latter possibility was investigated by comparing DNA restriction patterns of Staphylococcus epidermidis strains with those of their lysogenized derivatives. In vitro lysogenisation was obtained by exposing the strains to phage 118II. The pulsed patterns of the lysogenized strains were compared to those of their parental strains, revealing a shift in size of approximately 50 kb in a single band which was shown by Southern blotting to contain prophage. One strain was lysogenized ten times, revealing a potential preferred attachment site for phage 118II. These results confirm that chromosomal integration of a phage can be responsible for minor stable variations in DNA restriction patterns.

Blotting, Southern↗
PubMed1993

An improved assay for the detection of Toxoplasma gondii antibodies in human serum by flow cytometry.

The diagnosis of toxoplasmosis relies primarily on the demonstration of specific antibodies to Toxoplasma gondii. We describe a flow cytometry method for the determination of antibodies to whole fixed tachyzoites by indirect immunofluorescence. Fixed tachyzoites in suspension have characteristic light scattering properties. The amount of IgM, IgG, and IgA antibodies from patients' sera bound to the tachyzoites can be estimated from the mean fluorescence intensities observed using class-specific conjugates for different Ig heavy chains. Appropriate serum dilutions for the estimation of specific IgG titres and for the discrimination between sera positive and negative for IgA and IgM antibodies were established using 40 random sera from pregnant women. The method proved to be quantitative and highly sensitive as compared with currently used assays. Coefficients of variation between series ranged from 6.4% to 12.2% and could be controlled by the inclusion of positive and negative standard sera in the test series. The method might represent a major improvement in cost effectiveness as compared with routine immunofluorescence assay by fluorescent microscopy when the volume of testing is sufficient. It can be fully automated, and its large scale application is currently under investigation.

Animals↗
PubMed1993

Early events in the experimental interstitial lung disease induced in sheep by the Visna-maedi virus.

Visna-maedi virus is a lentivirus closely related to the human immunodeficiency virus type I (HIV-I). During spontaneous infection of sheep by Visna-maedi virus an interstitial lung disease is observed. It is characterized by an alveolitis, peribronchovascular lymphoid nodules, alveolar wall thickening and myomatosis. In order to decipher the pathology of this lentiviral infection we have induced this disease in colostrum-deprived newborn lambs.

Animals↗
PubMed1991

Seventeen years of surgical treatment of thymoma: factors influencing survival.

We report on 17 years experience of the surgical treatment of thymoma in 65 patients, 11 with and 54 without myasthenia gravis. Patients were staged using the French "GETT" classification; 38 were in stage I (no invasive tumor), 6 in stage II, 13 in stage III and 8 in stage IV. In 45 patients, surgical excision was total while the remaining 20 underwent partial resection only. Postoperative radiotherapy was given in 12 cases, and 17 received a combination of radiotherapy and chemotherapy. One patient was lost to follow up, but no operative death occurred in the series. The mean survival for all patients was 70 +/- 7 months, and the 5- and 10-year survival was 91% +/- 4% and 69% +/- 8%, respectively. Follow-up for the 47 patients still alive and 4 patients deceased from unrelated causes ranged from 1.5 to 180 months (mean 142 +/- 10 months). Our data indicate that the prognosis of thymoma relates to radiological discovery (P less than 0.01), total surgical resection (P less than 0.01) and stage of tumor (P less than 0.01). It is not influenced by age, sex, tumor cell type or the presence or absence of myasthenia gravis.

Adult↗
PubMed1990

In vivo activation of alveolar macrophages in ovine lentivirus infection.

Sheep infected by visna-maedi virus, a lentivirus related to the human immunodeficiency virus, develop a chronic interstitial lung disease. Since monocyte/macrophages are known to be specifically infected by visna-maedi virus, we investigated the role of macrophages in the appearance of pulmonary lesions in animals with naturally occurring disease. Alveolitis in maedi leads to a doubling in bronchoalveolar lavage total cell counts and of macrophages as compared to normal sheep. A significant increase in the relative percentage of neutrophils was also observed, accompanied by an increased spontaneous release of neutrophil chemotactic activity by alveolar macrophages of diseased animals, suggesting that they may be activated. Macrophage activation is also demonstrated by the observation of a significant (x3) increase of spontaneous fibronectin release by alveolar macrophages from maedi lungs, and furthermore by the high level expression of major histocompatibility complex class II antigens on most of these cells. Thus viral infection, although restricted to a small population of macrophages, is able to modulate extensive activation of macrophages in the lung. Activated macrophages release mediators likely to play a role in the development of the alveolitis and the parenchymal desorganization. These findings may be relevant to our understanding of the mechanisms by which human immunodeficiency virus infection leads to pulmonary disease other than that caused by opportunistic infections.

Animals↗
PubMed1990

[Diffuse interstitial pneumopathies caused by lentivirus (HIV-1) in humans and animals].

Lentiviruses belong to the retroviruses family (ie RNA viruses with reverse transcriptase activity); they induce inflammatory and/or degenerative slowly progressive diseases, affecting various organs. Some lentiviruses preferentially infect lymphocytes (HIV-1 and HIV-2, SIV and FIV) and are associated with infectious and tumoral disorders. Most lentiviruses induce a pulmonary disease, typically diffuse interstitial pneumonia. The visna/maedi-virus of sheep infects monocyte macrophage cells and the pulmonary lesions are macrophagic and neutrophilic alveolitis, lymphoid infiltration, myomatosis and interstitial fibrosis. Such pulmonary lesions are also induced by the goat and equine lentiviruses. In humans infected by HIV-1 or HIV-2, a diffuse interstitial lung disease also occurs; the histological findings are of alveolitis associated with lymphoid peribronchovascular infiltrates. The mechanism of formation of the lesions involves complex cellular interactions (especially between macrophage and lymphocyte, via cytokine production). These interactions are well modelled by small ruminant lentivirus induction of interstitial pneumonia.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Regulation of S-adenosyl methionine synthesis in the mouse embryo.

In early embryos, methylation is involved in "gamete imprinting" and inactivation of artificially introduced foreign genes. We studied the biosynthesis of the universal methylation cofactor: S-Adenosyl methionine (SAM). In the mouse, SAM conversion from methionine is limited by saturation of the methionine endogenous pool. SAM is present at a practically unchanged level from the unfertilized oocyte to early morula. SAM synthesis is increased at the time of compaction. In blastocysts, although methionine uptake is increased, the conversion rate from methionine is lowered. We observed no differences between C57 Black and Swiss albino random bred strains. In few experiments with human unfertilized oocytes and spared embryos, we observed higher methionine incorporation, and higher conversion to SAM. Next, the effect of two methylation inhibitors was tested, on early mouse embryonic development, at the one-cell and the two-cell stage. We found that ethionine is very toxic, even at the lowest tested concentration of 25 microM. Homocysteine is more potent at the one-cell stage than at the 2-cell stage, and it only partially blocks blastocyst formation from the 2-cell stage even at a concentration of 500 microM. It clearly acts as a methylation inhibitor; it lowers the SAM pool and the methylation index, SAH/SAM ratio (SAH: S-Adenosyl Homocysteine). We also found that homocysteine is an unexpected competitor for methionine influx and efflux.

Animals↗
PubMed1981

Glycoproteins of platelet membranes from Glanzmann's thrombasthenia. A comparison with normal using carbohydrate-specific or protein-specific labelling techniques and high-resolution two-dimensional gel electrophoresis.

Platelets from Glanzmann's thrombasthenia patients and from normal donor were surface labeled by techniques specific for sugars (terminal sialic acid, penultimate galactose/N-acetylgalactosamine) and proteins (tyrosine-histidine residues). These labelled platelets were solubilized in sodium dodecyl sulphate and separated on a two-dimensional electrophoretic system [O'Farrell. P. H. (1975) J. Biol. Chem. 250, 4007--4021] first according to their isoelectric point (pI) and then according to their molecular weight. In addition, unlabelled sodium-dodecyl-sulphate-solubilized platelets were separated on a two-dimensional polyacrylamide gel and the glycoproteins were identified by binding of 125I-labelled Lens culinaris lectin (specific for mannose and glucose). In one Glanzmann's thrombasthenia patient glycoproteins IIbA1 and IIIaA1 were absent and in two others lower amounts of two glycoproteins were found in positions similar or close to these two membrane glycoproteins. The terminal sialic acid moieties of major glycoproteins (IbA1, IbB1 and IIIbA1) were more intensely labelled in Glanzmann's thrombasthenia than in normals and these glycoproteins had an altered pI. A glycoprotein tentatively designated as Ic/IIa(?) had an altered pI and was labelled more intensely in Glanzmann's thrombasthenia platelets than in normals. A number of low-molecular-weight glycoproteins (IVa, IVb, VII) and one high-molecular weight glycoprotein normally found in platelets of healthy donors were reproducibly not detected in Glanzmann's thrombasthenia platelets. These results obtained by a combination of highly sensitive techniques strongly indicate that in Glanzmann's thrombasthenia the absence or reduction of two major membrane glycoproteins (IIbA1, IIIaA1) is not the only defect but that there appears to be a profound perturbation of the platelet membrane surface.

Blood Platelet Disorders↗
PubMed1981

Immunochemical properties of antigens present on immature erythrocytes from mouse and rat.

Rabbit antisera directed against erythrocytes from anemic mice or from newborn rats, once absorbed on homologous normal adult erythrocytes, recognize antigens present respectively on immature erythrocytes from anemic adult mice or rats (Im M and Im R antigens). Using iodinated immature erythrocytes from both species, homologous sera precipitated two populations of antigens showing 230,000 D and 95,000 D molecular weights. Im M antigens (230,000 and 95,000 D) were partially precipitated using anti-Im R serum. After total absorption of the sample by anti-Im R serum, both 230,000 and 95,000 D antigens were still immunoprecipitated using anti-Im M serum. Similar results were obtained using Im R antigens and anti-Im M serum then anti-Im R serum. This demonstrates that some Im specificities are common to rat and mouse while others, showing identical molecular weights, are species-specific.

Animals↗
PubMed1981

Measles virus: evolution of a persistent infection in BGM cells.

An African green monkey kidney cell line (BGM) persistently infected with measles virus (BGM/Hallé cells) has been studied during 3 years in culture. The early cell passages were characterized by slow growing cultures producing high yields of infections virus (10(6)--10(7) PFU/ml). These cells were gradually replaced by a population of cells multiplying at a similar rate as non-infected cells. During this evolution, the virus released from the cells changed from a large plaque variant, to a small plaque and eventually unlysed foci. Despite greater than or equal to 95 per cent of the cells being infected, the virus yield fell to the limits of detection. [35S]-methionine labelling of BGM/Hallé cultures at the 20th and 140th passage showed that in both cases all the measles virus structural proteins were synthesized. There were no changes in the apparent molecular sizes of the viral proteins during passage. Cell surface [125I]-labelling of BGM/Hallé cells indicates that viral envelope antigens are inserted into the membrane despite the diminution in virus yield. Several cell proteins not labelled in non-infected BGM cells are also labelled. These proteins could also be [125I]-labelled in clones of BGM/Hallé cells with had been "cured" of virus. Chase experiments of [125I]-pre-labelled BGM/Hallé cultures showed the radiolabelled antigen to be incorporated into virus particles. Non-infections virus particles released from the cells contained the same polypeptides as those released from a lytic infection.

Animals↗