Search PubMed⌕ Search

Biomedical subjects

T Marchal

Publications and source records attributed to T Marchal.

At least 19 recordsLinked to original sources
PubMed2004

Mycobacterium tuberculosis infection in a dog from Africa.

A 4-year-old male Boxer dog with a history of vomiting, diarrhea, and weight loss moved from West Africa to Lyon, France, where it was further evaluated. Radiographs revealed pleural effusion and enlargement of tracheobronchial lymph nodes and liver. Cytologic examination of the pleural effusion and a fine needle aspirate specimen of the liver showed mixed mononuclear inflammation with nonstaining rod structures within epithelioid histiocytes. At necropsy, the main gross pathologic findings were exudative pleuritis, nodular hepatitis, and infarcts and caseous nodules in the kidneys. The main histologic lesions were granulomatous hepatitis, granulomatous pneumonia, fibrinous leukocytic pleuritis, necrotic and fibro-calcified granulomatous lymphadenitis, and granulomatous nephritis. A Ziehl-Neelsen stain applied to both cytologic and histologic samples was positive for acid-fast bacilli. Bacterial culture of the pleural fluid was positive for Mycobacterium tuberculosis. Cytology is a valuable tool in the diagnosis of this important zoonotic disease.

Animals↗
PubMed2003

Probing complex RNA structures by mechanical force.

RNA secondary structures of increasing complexity are probed combining single molecule stretching experiments and stochastic unfolding/refolding simulations. We find that force-induced unfolding pathways cannot usually be interpreted by solely invoking successive openings of native helices. Indeed, typical force-extension responses of complex RNA molecules are largely shaped by stretching-induced, long-lived intermediates including non-native helices. This is first shown for a set of generic structural motifs found in larger RNA structures, and then for Escherichia coli's 1540-base long 16S ribosomal RNA, which exhibits a surprisingly well-structured and reproducible unfolding pathway under mechanical stretching. Using out-of-equilibrium stochastic simulations, we demonstrate that these experimental results reflect the slow relaxation of RNA structural rearrangements. Hence, micromanipulations of single RNA molecules probe both their native structures and long-lived intermediates, so-called "kinetic traps", thereby capturing -at the single molecular level- the hallmark of RNA folding/unfolding dynamics.

Computer Simulation↗
PubMed2003

High-grade canine T-cell lymphoma/leukemia with plasmacytoid morphology: a clinical pathological study of nine cases.

The aim of this study is to determine the clinical, morphological, and immunophenotypical presentation of 9 cases of a particular type of canine T-cell lymphoma/leukemia. The morphological presentation was a diffuse infiltration of small, medium-sized, or large blast cells with eccentric nuclei, hyperbasophilic cytoplasm, and a juxtanuclear, pale cytoplasmic area, giving a plasmacytoid appearance and suggesting a B-cell morphology. Surprisingly, all 9 cases were of T-cell phenotype (CD3+). Among the 7 immunophenotyped cases, 4 were CD4-/CD8+, 2 CD8+/CD4+, and 1 CD4+/CD8-. The median Ki-67 index was 65.7%, which placed this lymphoma in the high-grade group. This type of lymphoma/leukemia was found in dogs between 1 and 11 years of age, with a median age of 5.8. The male-female ratio was 0.8 for a reference population of 1.04. The most significant clinical findings were lymphadenopathy either generalized or localized in all cases, a mediastinal mass in 4 cases, bone marrow involvement in 7 cases, hypercalcemia in 4 cases, along with an aggressive clinical course and a poor response to chemotherapy in all cases, with a median disease-free survival time of 3 months.

Animals↗
PubMed2002

Canine T-cell lymphomas: a morphological, immunological, and clinical study of 46 new cases.

The aim of this study is to report 46 new cases of canine T-cell lymphomas among a series of 140 lymphomas studied by immunophenotyping (incidence 32.8%). According to the updated Kiel classification adapted to the canine species, 13 were classified as low-grade and 33 as high-grade lymphomas. Among the low-grade lymphomas, five were small clear-cell lymphomas, three were pleomorphic small-cell lymphomas, and five mycosis fungoides. Among the high-grade cases, there were 11 pleomorphic mixed-, small-, and large-cell lymphomas, 6 pleomorphic large-cell lymphomas, 11 lymphoblastic lymphomas, and 5 unclassifiable high-grade plasmacytoid lymphomas. The cytohistologic features were highly suggestive of a T-cell phenotype on the basis of cell morphology (irregular nuclei and clear cytoplasms) (30/46 cases), a T-cell zone pattern, and the presence of hyperplastic postcapillary venules (22/46 cases). All 46 cases were CD3+ CD79a-, and among 34 cases investigated for CD4 and CD8 expression, 13 were CD4+CD8-, 13 were CD8+CD4-, and 8 were CD4CD8 double positive or double negative. The pleomorphic mixed lymphomas were mainly CD4+CD8- (6/7) and the lymphoblastic lymphomas were double positive or double negative (6/8). The main clinical, hematologic, and biochemical features were generalized (28/46) or regional lymphadenopathy (16/46), hepatosplenomegaly (15/46), extranodal involvement (11/46), mediastinal mass (9/46), and leukemia (8/46), which were mainly present in cases of lymphoblastic lymphomas and hypercalcemia (16/46).

Animals↗
PubMed2000

Cellular immune response of lymph nodes from dogs following the intradermal injection of a recombinant antigen corresponding to a 66 kDa protein of Echinococcus granulosus.

A recombinant polypeptide (referred to as EgA31), which represents a 66kDa protein, was prepared from an Echinococcus granulosus cDNA library. In order to assess its potential to induce cellular immune responses, dog popliteal and prescapular lymph nodes were sensitized with this recombinant polypeptide. Subpopulations of lymphocytes were then analyzed by flow cytometry and immunohistochemistry on lymph node sections. Five days after the sensitization, the paracortical areas of the lymph nodes appeared hypertrophic, the number of CD3+, CD4+, CD8+ and CD5+ cells increased, the number of B-cells began to augment and some secondary follicles occurred, and a number of CD4+ cells appeared in germinal centers. Many large secondary follicles and a significantly augmented number of CD5+ cells in cords of medullae were observed 10 days after the sensitization. These active cellular responses strengthen the interest for further studies on the development of a vaccine with this recombinant polypeptide.

Animals↗
PubMed1998

Effect of PGE1 on TNF-alpha status and hepatic D-galactosamine-induced apoptosis in rats.

Prostaglandin E1 has hepatoprotective properties in several clinical and experimental models of liver dysfunction. Hepatotoxicity induced by D-galactosamine (D-GalN) is a suitable animal model of human acute hepatic failure. The aim of the study was to investigate if prostaglandin E1 (PGE1) protection against hepatic D-GalN-induced apoptosis was related to tumour necrosis factor-alpha (TNF-alpha) content in serum. This cytokine is associated with in vitro apoptosis and general inflammatory disorders. In this study, PGE1 was administered 30 min before D-GalN to rats. In other experiments, several doses of TNF-alpha were administered 15min after PGE1 to D-Ga1N-treated rats. Several parameters related to apoptosis and necrosis were measured by flow cytometry, gel electrophoresis, biochemical analysis, and optical and electron microscopy. Tumour necrosis factor-alpha was quantified by competitive enzyme-linked immunosorbent assay (ELISA). PGE1 by itself did not modify the cell cycle of hepatocytes and liver toxicity, but increased TNF-alpha in serum in comparison with the control group. D-Galactosamine increased the percentage of hepatocytes in apoptosis and in the S phase of the cell cycle, and decreased those in G0/G1. Such an increase of hepatocytes in apoptosis was correlated with a higher number of apoptotic bodies and DNA fragmentation in liver than control samples. Also, D-GalN increased alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase and TNF-alpha in serum compared with the control group. Pre-administration of PGE1 to D-GalN-treated rats reduced all the parameters of apoptosis and necrosis in liver, and increased additionallyTNF-alpha content in serum. In those experiments where low doses of TNF-alpha were administered to PGE1 and D-GalN-treated rats an inverse relationship appeared between TNF-alpha and ALT content in serum. In conclusion, the protective effects of PGE1 on D-GalN-induced apoptosis may be linked to its capacity to modulate cell division and/or its immunomodulatory activity. In this sense, our experimental results suggest that TNF-alpha could be involved in protection or exacerbation of liver damage in relation to the pathophysiological status of the liver.

Alprostadil↗
PubMed1997

Cytohistological and immunological classification of canine malignant lymphomas: comparison with human non-Hodgkin's lymphomas.

Non-Hodgkin's lymphomas (NHLs) in man are on the increase. They are also common in dogs, which, as close companions of man, may constitute a useful experimental model. However, comparisons cannot be made without a reliable morphological and immunological classification of canine NHL. Canine NHLs (n = 134) were classified on the basis of fine-needle lymph-node aspirates according to the Kiel classification, and 92 were re-classified according to the Working Formulation and the updated Kiel classification, in a histological and immunological study. The immunophenotype was determined (1) in 92 cases by the use of the pan-T anti-CD3 polyclonal antibody and the pan-B anti-mb1 monoclonal antibody on paraffin wax-embedded tissue sections, and (2) in 47 cases by the use of a panel of polyclonal and monoclonal antibodies on fresh preparations and frozen tissue. Cytological analysis showed a predominance of high-grade lymphomas (73.9%) over low-grade lymphomas (26.1%); it also demonstrated forms not reported in other species (small-cell variants, lymphomas with macronucleolated medium-sized cells [MMCs], and polymorphic lymphomas with a centroblastic component). Histological examination revealed the rarity of follicular lymphomas (2.2% of cases), an appearance suggestive of T-cell neoplasia (8.7% of cases), and evidence that some MMC lymphomas originated in the marginal perifollicular zones. Some (26%) of the lymphomas were of the T-cell phenotype: the majority of these consisted of small-cell, low-grade lymphomas and mycosis fungoides, the rest being either high-grade pleomorphic lymphomas (mixed or large-cell) or, rarely, high-grade, small noncleaved-cell, plasmacytoid lymphomas. No lymphoma expressed a double (T and B) phenotype. This study revealed similarities with, but also notable differences from, human NHL. In particular, the MMC lymphomas may constitute an interesting equivalent of human marginal zone B-cell lymphomas.

Animals↗
PubMed1997

Growth fractions in canine non-Hodgkin's lymphomas as determined in situ by the expression of the Ki-67 antigen.

The proportion of proliferating cells in non-Hodgkin's lymphomas (NHLs) as determined in situ by the expression of the Ki-67 antigen, has prognostic value in human oncology, and is strongly related to the different grades of malignancy. The evaluation of the Ki-67 index in canine NHLs may be useful in assessing the individual variability of the growth fraction in the different sub-types of lymphoma, and also the validity of the classification in terms of grade of malignancy. The growth fraction was evaluated in 92 canine NHLs, previously classified according to the Kiel classification (as adapted to the canine species), by determining the expression of the Ki-67 antigen with the MIB1 antibody on (1) paraffin-wax tissue sections in all 92 cases, and (2) fine-needle aspirates or tumour imprints in 30 cases. The labelling appeared satisfactory in 88% of the cases, with good concordance between the histological and cytological data. A highly significant correlation (P < 0.001) was established between the proportion of Ki-67+ cells and the classification into low-grade (Ki-67 index < 21%) and high-grade malignancy (Ki-67 index > 21% and usually > 29%). In the low-grade lymphoma group, a macronucleolated medium-sized-cell lymphoma not found in man had the lowest proliferation index. In the high-grade malignancy group, the number of Ki-67+ cells seemed to be proportional to cell size, whatever the phenotype, with the rare exceptions of some unclassifiable small-cell Burkitt-type or plasmacytoid lymphomas, which were highly proliferating. The classification of lymphomas into low-grade and high-grade appears to correlate well with their proliferative index. The existence of individual variations, within given categories of canine NHL, suggests that, as in human medicine, prognosis may be assisted by determining the growth fraction at initial diagnosis, and by fine-needle aspiration at relapses.

Animals↗
PubMed1997

Immunophenotype of the canine transmissible venereal tumour.

The canine transmissible venereal tumour is a naturally occurring contagious round-cell neoplasia which is primarily located in the mucous membrane of the external genitalia in dogs of either sex. In order to specify the controversial cytogenetic origin of this round-cell tumour, 14 cases of canine transmissible venereal tumour, formalin- or Bouin-fixed and paraffin-embedded, were subjected to extensive immunophenotypic analysis using reagents specific to a variety of cytoplasmic or surface antigens: lysozyme, ACM1 antigen, vimentin, neuron-specific enolase, glial fibrillary acidic protein, desmin, alpha smooth muscle actin, CD3, IgG, kappa and lambda light chains, and keratin. Lysozyme immunoreactivity was detected in all cases, ACM1 antigen in 11 of 14, neuron-specific enolase in 11 of 14, vimentin in 10 of 14, glial fibrillary acidic protein in 4 of 14 and desmin in 1 of 14. All the sections were negative to keratins, alpha smooth muscle actin and CD3, whereas in five cases, perivascular tumour cells contained Ig G, kappa and lambda light chains. The immunoreactivity to lysozyme and ACM1 antigen supports the hypothesis of a histiocytic immunophenotype for the canine transmissible venereal tumour.

Animals↗
PubMed1997

Immunophenotypic characterization of feline Langerhans cells.

To carry out the characterization of feline Langerhans cells (LC), first described in 1994, we used a panel of monoclonal antibodies (MAb) known to react with human, canine and feline leukocyte membrane antigens (Ag). The immunolabeling was performed, at light microscope level, on frozen sections of feline skin and labial mucosa using an avidin-biotin-peroxidase technique, and at electron microscope level on epidermal cell suspensions using an immunogold technique. Out of the 52 MAb tested, six labeled basal or suprabasal DC cells in the frozen sections, either in epidermis or lip epithelium: MHM23 (anti-human CD18), CVS20 and vpg3 (respectively anti-canine and feline-major histocompatibility complex class II molecules), vpg5 (anti-feline leukocytes), vpg39 (anti-feline CD4) and Fel5F4 (anti-feline CD1a). These six MAb were used on suspensions, and labeled cells which showed no desmosomes or melanosomes, but contained 'zipper-like' structures similar to Birbeck granules (BG) in their cytoplasm, revealing they were LC. Consequently, feline LC are CD18-positive (CD18+), major histocompatibility complex class II-positive (Class II+), CD1a-positive (CD1a+), vpg5-positive (vg5+) and CD4-positive (CD4+). This immunophenotypic and ultrastructural characterization demonstrates that feline LC share many characteristics with their human counterparts, a fact that will allow us to study the role of feline LC in certain feline diseases such as Feline Immunodeficiency Virus (FIV) infection, since it has been shown that human LC cells are HIV-permissive, and to establish an animal model for human AIDS.

Animals↗
PubMed1997

Quantitative assessment of feline epidermal Langerhans cells.

The densities of feline epidermal dendritic cells expressing CD18, MHC class II and CD1a antigens were determined for four anatomical locations in 19 cats of European breed in blind conditions. The densities (+/- SD) of CD1a+ Langerhans cells in the skin of the abdominal wall (269 +/- 68 cells/mm2), the back (363 +/- 19), the internal side of the ear (572 +/- 30) and the external side of the ear (502 +/- 32) were significantly different, with young and old animals displaying less stained cells than adults. No significant differences in the mean densities were found with regard to sex, colour or antibody used.

Abdomen↗
PubMed1996

[Clinical, morphologic and immunophenotypic data based on 10 cases of canine muco-cutaneous epidermotropic T-lymphoma (analogous to Mycosis Funcgoïde). Important of an animal model of spontaneous pathology].

Our serie of ten canine cutaneous epitheliotropic T-cell lymphomas (CTCL), is found in old dogs, belonging mainly to the Boxer breed. Site on the mucous membranes (especially buccal), the muco-cutaneous junctions, their clinical expression is polymorphous. Lesions, follow on one after another (erythema, plaques, nodules) and are diversely associated in a given animal, the borders between the different stages often being difficult to establish. Adenopathies noted at the time of the diagnosis or during the course of the condition are accompanied by an involvement of the blood and organs (analogous to Sézary's disease). The progression of the disease can be very rapid in the buccal forms, which are generally aggressive, and in cases of violent, uncontrollable pruritus, which may be disturbing for the owner (with requests for euthanasia). The neoplastic infiltrate is constituted of small lymphocytes with hyperchromatic, convoluted nuclei (incipient stages), then large cells with a "histiocytic" appearance for the nodules. Epitheliotropism, which is maximal for the infiltrated plaque stage, shows up either in the form of a flux of totally epitheliotropic isolated cells (Ketron-Goodman type) or in that of Pautrier abscess-like collections. THe veterinary literature is in agreement that the CTCL cell expresses CD3, but two recent studies are in contradiction as regards its membership of helper or cytotoxic/suppressor populations. For our 10 cases, all the cells of lymphocytic morphology were, without exception, CD3+ and CD45+, irrespective of their situation within the epithelium or the chorion. The CD3+ cells in the epithelium were systematically CD8+, CD4- (confirming P.F. Moore's observations), expressing CD5 in a variable way, and, mostly, the Ki-67 nuclear proliferation Ag. The CD3+ cells of the chorion were exclusively, or mainly, CD8+, and occasionally CD4+. They expressed CD5 in a variable way, and, for a minority, the Ki-67 nuclear proliferation Ag. On the pathogenic level, it may be suggested that a T clone, CD8+, undergoes the "homing" phenomenon within the epithelium, enters the cell cycle, then manifests a tropism towards the chorion, which it infiltrates. Despite some particularities, which may be clinical (serious mucous attacks), cytological (the "histiocytic" appearance of the nodule cells) or immunophenotypic (expression of CD8, similar to what is observed in man in a considerable number of Pagetoid reticulosis), CTCL constitutes an interesting model of spontaneous pathology, and could prove useful in: - identifying various etiological factors (given that the dog, as a close commensal of man, is subject to the same environmental factors).

Animals↗
PubMed1995

Lymphocyte subset abnormalities in German shepherd dog pyoderma (GSP).

Peripheral blood lymphocyte subpopulations were studied in 12 German shepherd dogs suffering from deep pyoderma (GSP). Twelve other healthy but matched dogs were used as controls. GSP was found to be associated with an imbalance in the CD4 and CD8 subsets (respectively 37.3 +/- 8.7% and 28.6 +/- 6.6%, as compared to 47.5 +/- 8.8% and 19.3 +/- 4.0% in the controls). The activation markers were not affected by GSP. Moreover, analysis of the B-cell populations showed a striking decrease in the level of CD21 cells (5.5 +/- 3.3% of CD21+ lymphocytes, compared to 12.2 +/- 6.0 in the controls). This study suggests that the immunological imbalance observed in GSP may be associated with defective helper cells, and provides further evidence that dogs suffering from GSP are not immunologically normal reactors.

Animals↗
PubMed1995

An original perifollicular zone cell in the canine reactive lymph node: a morphological, phenotypical and aetiological study.

In this study of 109 canine reactive lymph nodes, the perifollicular zone (PZ) cell was characterized by cytological, histological, immunocytochemical and electron microscopical techniques. The PZ cell was always found in association with plasma cell hyperplasia. Its main cytological characteristics were medium size, fine chromatin and a large central prominent nucleolus with a small amount of pale cytoplasm. It was located in a clearly recognizable PZ surrounding the follicles; this zone was particularly well developed at the capsular pole of the lymph node. Electron microscopical findings indicated a poorly differentiated cell. Immunolabelling indicated a CD3-, cIg-, Ki-67- immunophenotype, suggesting a resting B cell. These results suggest that the PZ cell belongs either to a post-follicular stage between large immunoblasts and plasma cells or, as is more likely, to a pre-follicular lymphoid subpopulation occurring early in the B-cell differentiation scheme, as with most human marginal zone (MZ) cells. Its high frequency of occurrence in reactive lymph nodes in mammary tumour lymphadenopathies, systemic lupus erythematosus and leishmaniasis, suggests that the PZ cell has a special role in the canine immune response, or perhaps in the arrested maturation of the normal developmental process.

Animals↗