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Biomedical subjects

M Redard

Publications and source records attributed to M Redard.

14 recordsLinked to original sources
PubMed1997

Crucial role of tumor necrosis factor (TNF) receptor 2 and membrane-bound TNF in experimental cerebral malaria.

Tumor necrosis factor (TNF) has been implicated in the pathogenesis of experimental cerebral malaria (CM), but the respective role of its two types of receptors has not been established. A significant increase in the expression of TNF-receptor 2 (TNFR2, p75), but not of TNFR1 (p55), was found on brain microvessels at the time of CM in susceptible animals. Moreover, mice genetically deficient for TNFR2 (Tnfr2null) were significantly protected from experimental CM, in contrast to TNFR1-deficient (Tnfr1null) mice, which were as susceptible as wild-type mice. To identify the factors involved in the protection from CM conferred by the lack of TNFR2, we assessed in both knockout and control mice the serum concentrations of mediators that are critical for the development of CM, as well as the up-regulation of intercellular adhesion molecule-1 (ICAM-1) in the brain microvessels. No significant difference in serum levels of TNF and interferon-gamma was found between infected wild-type and Tnfr1null or Tnfr2null mice. Interestingly, the pronounced ICAM-1 up-regulation and leukocyte sequestration, typically occurring in brain microvessels of CM-susceptible animals, was detected in infected control and Tnfr1null mice-both of which developed CM-whereas no such ICAM-1 up-regulation or leukocyte sequestration was observed in Tnfr2null mice, which were protected from CM. Making use of microvascular endothelium cells (MVEC) isolated from wild-type, Tnfr1null or Tnfr2null mice, we show that soluble TNF requires the presence of both TNF receptors, whereas membrane-bound TNF only needs TNFR2 for TNF-mediated ICAM-1 up-regulation in brain MVEC. Thus, only in MVEC lacking TNFR2, neither membrane-bound nor soluble TNF cause the up-regulation of ICAM-1 in vitro. In conclusion, these results indicate that the interaction between membrane TNF and TNFR2 is crucial in the development of this neurological syndrome.

Animals↗
PubMed1997

Cellular retinol-binding protein-1 is expressed by distinct subsets of rat arterial smooth muscle cells in vitro and in vivo.

Previous work (M.-L. Bochaton-Piallat, P. Ropraz, F. Gabbiani, G. Gabbiani, Arterioscler Thromb Vasc Biol 1996, 16:815-820) has shown that a subset of smooth muscle cell (SMC) clones derived from the normal rat aortic media displays an epithelioid phenotype similar to that of the whole SMC population cultured from the intimal thickening 15 days after endothelial injury (IT-15). We show here that the whole IT-15 SMC population and the epithelioid clones, derived either from the normal media or from the IT-15, express cellular retinol-binding protein-1 (CRBP-1), a protein involved in retinoid metabolism. The expression of CRBP-1 is accompanied by the expression of cytokeratin 8. In both whole SMC population cultured from IT-15 and epithelioid clones, retinoic acid modulates the transition from the epithelioid phenotype to the spindle phenotype, typical of whole SMC populations cultured from the rat normal aortic media. Moreover, after endothelial injury in vivo, a CRBP-1 expressing SMC subset appears transiently in the IT and disappears, allegedly by apoptosis, when re-endothelialization takes place. Our results suggest that the expression of CRBP-1 is a marker of arterial SMC activation after endothelial injury in vivo and that CRBP-1 and probably retinoids participate in this process.

Animals↗
PubMed1995

Intra-arterial beta irradiation prevents neointimal hyperplasia in a hypercholesterolemic rabbit restenosis model.

BACKGROUND: Intra-arterial gamma irradiation has been shown to reduce restenosis after balloon angioplasty. The use of beta emitters should allow similar effects while inducing less undue tissue irradiation radioprotection problems. METHODS AND RESULTS: Flexible 90-yttrium (90Y) coils inside a centering balloon were used to allow homogeneous intraarterial dose delivery. One carotid and one iliac artery of 21 hypercholesterolemic rabbits were deendothelialized and then irradiated. Four dose schedules were studied: (1) control (dilated, nonirradiated); (2) 6 Gy; (3) 12 Gy; and (4) 18 Gy. Arterial specimens were histologically evaluated at 8 days and at 6 weeks. For all radiation doses at 8 days compared with controls, there was a significant decrease in bromodeoxyuridine-labeled cells (245 +/- 93 cells/cm in control, 42 +/- 27 in 6 Gy, 72 +/- 107 in 12 Gy, and 2 +/- 2 in 18 Gy groups; P < .001) and in total neointimal cells (891 +/- 415 cells/cm in control, 79 +/- 43 in 6 Gy, 192 +/- 264 in 12 Gy and 22 +/- 13 in 18 Gy groups; P < .0002). At 6 weeks, computer-derived histological percent area stenosis was reduced from 26 +/- 10% in the control group to 1 +/- 1.3% in the 18 Gy group (P < .0001), but lower doses had no significant effect. CONCLUSIONS: Administration of intra-arterial beta irradiation with a 90Y source is technically feasible and compatible with an ordinary catheterization laboratory environment. A dose of 18 Gy effectively induces long-term inhibition of neointimal hyperplasia.

Angioplasty, Balloon↗
PubMed1995

Cytoskeletal protein modulation in pulmonary alveolar myofibroblasts during idiopathic pulmonary fibrosis. Possible role of transforming growth factor beta and tumor necrosis factor alpha.

Pulmonary biopsy specimens from ten cases of idiopathic pulmonary fibrosis (IPF) were examined using routine histological stains, including toluidine blue, and immunohistochemistry by means of specific antibodies against alpha-smooth muscle (alpha-SM) actin, desmin, keratin, TGF beta 1, and TNF alpha. The sections were compared with two cases of normal lung. As shown previously, normal alveolar interstitium did not contain alpha-SM actin positive myofibroblasts nor did the alveolar lining contain any significant number of TGF beta 1 or TNF alpha laden epithelial cells. In IPF, during the inflammatory stage, the alveolar myofibroblasts expressed alpha-SM actin and the regenerating type II alveolar epithelium staining strongly with TGF beta 1 and TNF alpha antibodies. The former cytokine was also detected in the interstitial matrix and fibroblastic cells as well as in the wall of vessels. At this stage, a manifest mast cell infiltration was noted. In very fibrotic and cystic alveolar tissue, i.e., at end stage fibrosis, the number of alpha-SM actin positive myofibroblasts as well as that of TNF alpha laden type II epithelial cells diminished, while TGF beta 1 positive cells persisted. Our findings demonstrate that during IPF alveolar type II epithelium constitutes, if not the site of synthesis, at least the main reservoir for TGF beta 1 and TNF alpha. These cytokines, besides their involvement in fibrogenesis, play probably an important role in the expression of alpha-SM actin by alveolar myofibroblasts. Our study suggests the possibility of an interaction between interstitial cells and alveolar epithelium, during IPF.

Actins↗
PubMed1995

Apoptosis participates in cellularity regulation during rat aortic intimal thickening.

Intimal thickening induced after endothelial denudation of rat aorta is though to be due to migration and proliferation of smooth muscle cells (SMC). When the reendothelialization is achieved, intimal thickening shows an important decrease in cellularity. Using in situ end labeling of fragmented DNA and electron microscopy, we show that this remodeling is accompanied by apoptosis of SMC. The number of apoptotic SMC becomes important 15 days after endothelial injury and reaches a maximum at 20 days; at 45 days the intimal thickening is reendothelialized and no more apoptotic SMC are detected. Apoptotic SMC show nuclear and cytoplasmic condensation as well as cytoplasmic vacuolization. Our results indicate that apoptosis is an important mechanism in the regulation of intimal thickening evolution.

Animals↗
PubMed1995

Apoptosis mediates the decrease in cellularity during the transition between granulation tissue and scar.

Granulation tissue formation and contraction is an important step of second intention wound healing. Granulation tissue develops from the connective tissue surrounding the damaged or missing area and its cellular components are mainly small vessel and inflammatory cells as well as fibroblasts and myofibroblasts. As the wound closes and evolves into a scar, there is an important decrease in cellularity; in particular myofibroblasts disappear. The question arises as to which process is responsible for this cellular loss. During a previous investigation on the expression of alpha-smooth muscle actin in myofibroblasts (Darby I, Skalli O, Gabbiani G, Lab Invest, 1990, 63:21-29), we have observed that in late phases of wound healing, many myofibroblasts show changes compatible with apoptosis and suggested that this type of cell death could be responsible for the disappearance of myofibroblasts. We have now tested this hypothesis by means of morphometry at the electron microscopic level and by in situ end labeling of fragmented DNA. Our results indicate that the number of myofibroblastic and vascular cells undergoing apoptosis increases as the wound closes and support the assumption that this is the mechanism of granulation tissue evolution into a scar. The regulation of apoptotic phenomena during wound healing may be important in scar establishment and development of pathological scarring.

Animals↗
PubMed1993

Localization of alpha 2, alpha 5 and alpha 6 integrin subunits in human endometrium, decidua and trophoblast.

Integrins are heterodimeric glycoproteins acting as membrane receptors for extracellular matrix components. The specificity of these receptors towards one particular matrix glycoprotein depends on the type of alpha and beta subunit combination. Since integrins are involved in the migratory behaviour of cells and since cytotrophoblastic cells are constitutively invasive, we undertook to immunolocalize the alpha 2, alpha 5 and alpha 6 integrin subunits in normal and hydatidiform molar trophoblast, in an implantation site as well as in decidualized and non-decidualized endometrium. alpha 6 positivity was confined to villous cytotrophoblast and was clearly polarized towards the basement membrane. Extravillous cytotrophoblastic cells were alpha 6-negative but became alpha 5-positive. In contrast to normal trophoblast, villous cytotrophoblast from hydatidiform molar tissue was alpha 5-positive. We conclude that the expression of a alpha 5 integrin subunit on cytotrophoblastic cell surfaces is correlated with the appearance of an invasive phenotype. alpha 6 and alpha 2 integrin subunits were both localized on the surface and glandular epithelium of the endometrium and their expression was increased during the secretory phase but became low or undetectable after decidualization. In contrast, alpha 5 subunit positivity was weak in the same epithelial during the first half of the cycle but disappeared after ovulation. Stromal cell alpha 5 positivity was present throughout the cycle but increased dramatically in decidualized endometria. We conclude that the alpha 5 integrin subunit which disappears from the epithelium at the end of the cycle might allow migration of the epithelial cells and repair of the endometrium after menses. We also wonder if alpha 5 positivity is part of a change in the stromal cell phenotype induced by decidualization.

Decidua↗
PubMed1992

The comparative test performance of dot filter hybridization (Viratype) and conventional morphologic analysis to detect human papillomavirus.

To investigate the test performance of a commercially available detection kit for human papillomavirus (HPV), the relationship between the detection of HPV by dot filter hybridization (DFH) and by standard morphologic methods was studied. Four hundred two cervical samples taken from 381 patients referred to a colposcopy clinic were examined. Human papillomavirus DNA sequences were identified and typed using commercially available anti-sense RNA probes. Simultaneous cytologic smears were obtained in 289 patients, directed biopsy samples in 284, and both smears and biopsy samples in 171 samples. Human papillomavirus DNA was detected in 164 specimens (41%), of which 24 (15%) were type 6/11, 74 (45%) were type 16/18, 39 (24%) were type 31/33/35, and 27 (16%) were untyped due to the presence of multiple positive signals. Viral types 16/18 and 31/33/35 were eight and six times more frequent in cervical intraepithelial neoplasia (CIN) II/CIN III lesions than in condyloma/CIN I, respectively. When the cytologic diagnosis was considered the standard of reference, the results of DFH for the detection of HPV were concordant in 167 (56%) paired samples. The sensitivity of DFH was 48% and the specificity was 77%. The distribution of the morphologic diagnoses in the group of false-negative results and true-positive results was similar. When the histologic diagnosis was considered the standard of reference, the efficiency of DFH was 62%, the sensitivity was 59%, and the specificity was 79%. In the subgroup of 118 samples with simultaneous smear and biopsy and at least one positive examination, 42 (36%) were positive by all three methods, 42 (36%) by two, and 34 (29%) by one, including 6 (5%) by DFH alone. Fifteen cases more were detected by the complementary use of DFH and cytology than with cytology alone. The results demonstrated that the sets of patients positive for HPV when detected by DFH or by morphologic methods were not identical but rather overlapped. The detection of HPV may be slightly improved by using DFH in addition to conventional examinations. A significant number of HPV-positive patients without a morphologic lesion and patients with low-grade lesions had HPV 16/18 or 31/33/35, suggesting a possible role for typing in establishing a risk profile. However, given uncertainties in understanding the biology of HPV-associated lesions, the role, if any, of clinical testing for HPV by DFH remains to be defined.

Adolescent↗
PubMed1990

The application of immunocytochemical techniques to routinely-fixed and stained cytologic specimens. An aid in the differential diagnosis of undifferentiated malignant neoplasms.

Routinely-fixed and Papanicolaou stained smears with the cytologic diagnosis of undifferentiated malignant neoplasm that had been prepared with cells obtained by fine needle aspiration biopsy (n = 7), pulmonary lavage (n = 5), or thoracentesis (n = 3) from 15 unselected patients were stained by an immunocytochemical technique to evaluate the presence of keratin proteins and the leukocyte common antigen (LCA). Commercially available, well-characterized monoclonal antibodies with specificities for keratin proteins and the leukocyte common antigen, and a streptavidin-biotin-horseradish peroxidase labelling method were used. Evaluation of the stained smears revealed the presence of one of the two antigens in material obtained from each patient, thus indicating the probable cell-lineage of the neoplastic cells. The specificity of the monoclonal antibody reagents used was further evaluated in routinely-fixed and stained cytologic material from 24 histologically confirmed carcinomas and 12 lymphomas. In conclusion, immunocytochemical techniques may be successfully applied to routinely processed archival cytologic smears to determine the antigenic profile of morphologically undifferentiated cells and therefore aid in the differential diagnosis of undifferentiated malignant neoplasms.

Adult↗
PubMed1990

CA 125 is an excretory product of human endometrial glands.

The present investigation was undertaken to study the cellular localization and kinetics of synthesis of CA 125 in the endometrium. CA 125 was localized by immunohistochemistry to the infranuclear region of epithelial cells during the proliferative phase and to the apical luminal border during the secretory phase. In gestational endometrium, both the cytoplasm and the apical luminal border of epithelial cells were intensely positive. No staining was seen in endometrial stromal cells during the normal cycle or in decidualized endometria. Results obtained from in vitro cultures of separated glandular and stromal cells were similar to those obtained by immunohistochemistry. That is, epithelial cells released between 5 and 25 times more CA 125 into the culture medium than did stromal cells. The release of CA 125 was highest in epithelial and stromal cells obtained during the early secretory phase. CA 125 concentrations were markedly elevated in endometrial aspirations obtained during the secretory phase or in endometria with crumbling stroma compared to plasma levels. Plasma levels of CA 125 were slightly elevated during menses. These results suggest that CA 125 is an exocrine product of endometrial epithelial cells. Plasma levels of CA 125 may be of endometrial origin only when the membrane barriers, which normally prevent its entry into the circulation, are damaged.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1989

A simple method for estrogen receptor antigen preservation in cytologic specimens containing breast carcinoma cells.

We report a modified method to prepare cytologic specimens for the evaluation of estrogen receptors by immunocytochemistry. Cytologic samples were obtained by needle aspiration of tumor masses (nine patients) and body cavity fluids (nine patients). The cytologic material was divided, and slides for immunostaining were prepared according to two different techniques: (1) fixation of cells in suspension (modified method); and (2) fixation of cells adherent to slides (standard method). The results after immunostaining demonstrated that the number of cells adhering to slides prepared according to the modified method was greatly increased as compared with the number of cells remaining attached to slides prepared according to the standard method. There was no loss of cell groups or aggregates using the modified method. The antigenicity of estrophilin and the cell morphology were well-preserved for up to 30 days. With this modified method, cytologic samples may be stored and conveniently processed in batches, thereby improving the utilization of laboratory resources.

Antigen-Antibody Reactions↗
PubMed1987

Evaluation of estrogen receptors by immunocytochemistry on fine-needle aspiration biopsy specimens from breast tumors.

The estrogen receptor (ER) content of 31 surgically removed breast tumors (26 duct carcinomas, one lobular carcinoma, one papillary carcinoma, one colloid carcinoma, one duct carcinoma in situ, and one atypical fibroadenoma) was determined by a commercially available immunocytochemical method (Abbott Laboratories, ER-ICA) on cytologic material obtained by fine needle aspiration biopsy (FNAB) of surgical specimens. Immunocytochemical staining of cells by a peroxidase-antiperoxidase technique was evaluated on the basis of the percentage of positive cells and the intensity of staining. An immuno-staining score for cytologic (IS-CYTO) and histologic (IS-HISTO) material was defined and a threshold of positivity determined to facilitate the semi-quantitation of results and the comparison of cases. The results of immunostaining of cytologic material were compared with the evaluation of ER in corresponding tissue samples as determined by the radioligand binding assay using the dextran-coated charcoal procedure (ER-DCC) and by ER-ICA using cryostat sections of frozen tissue. The sensitivity, specificity, predictive value of a positive test, and test efficiency of ER-ICA in cytologic material as compared to ER-DCC was 96%, 83%, 96% and 93%, respectively. The IS-CYTO was significantly correlated with the IS-HISTO in corresponding histologic material (r = 0.72, P less than 0.001). In conclusion, the combination of ER-ICA with FNAB represents a useful new technique for the evaluation of ER which may be applied to small primary tumors, tumor recurrences, and metastases.

Axilla↗
PubMed1984

Culture of human endothelial cells derived from capillaries of the decidual tissue.

Human endothelial cells derived from the capillary bed of endometrial decidua were studied in vitro using medium 199 supplemented with 20% fetal calf serum. Cells in primary and subcultures were identified in parallel by electron microscopy and indirect immunofluorescence microscopy. The abundance of microfilaments appearing in small bundles, the micropinocytotic vesicles in the cell periphery, the occurrence of characteristic Weibel-Palade bodies and the intense and specific fluorescence after decoration with antibodies to Factor VIII protein--all were criteria for a positive demonstration of the endothelial character in the cell cultures derived from the capillary bed of the human decidua. The proliferative activity of the in vitro system was studied by autoradiography of the endothelial cells after exposure to [3H]-thymidine at various periods of incubation. A statistically highly significant difference (p less than 0.001) was found between periods of 4-6 and 6-8 days of incubation and between 6-8 and 8-10 days of incubation (p less than 0.01). No such difference was found between 8-10 and 10-14 days of incubation. When the medium was switched to complete M 199 + 10% fetal calf serum and 10% human plasma containing 76 pg/ml of estradiol the thymidine index was 5 to 4 times as high as in the control medium after 5 to 6 days of incubation. The results indicate that the in vitro system developed on endometrial capillaries derived from human decidua provides a stable low background of DNA synthesis against which small amounts of possible mediators of endothelial mitoses, e.g. estradiol, progesterone and various synthetic progestogens, can be tested.

Autoradiography↗