Ontogeny of T-cell surface molecules and receptors in the thymus.
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Animals↗
Biomedical subjects
G Goffinet
Publications and source records attributed to G Goffinet.
Malignant cell attachment to endothelium of ex vivo perfused human umbilical vein. Modulation by platelets, plasma and fibronectin.
The success of blood-born metastatic spread depends upon a key event: the tumor cell arrest and attachment to the host organ vasculature. In the present study, we have investigated interactions between several normal and cancer cell lines and vascular endothelium in a model of ex vivo perfusion of human umbilical vein. In this system, hydrodynamic parameters are monitored and endothelial cells are kept in their original environment known to modulate their phenotype. Metastatic tumor cell adhesion to the perfused endothelium was found to be significantly higher than that of normal cells tested. Platelets and soluble plasma factors including fibronectin promoted tumor cell arrest and adhesion to endothelium. Altogether our results indicate that the ex vivo perfusion of human umbilical vein allows the study of the interactions between malignant tumor cells, circulating plasma or blood cells and the endothelium during blood-born metastatic spread.
Blood Platelets↗
Perfusion of human umbilical veins. A new approach to study the interactions of circulating malignant cells with vascular wall and their modulations.
Interactions of malignant or non-malignant human and rodent cells with the vascular wall were studied using perfused human umbilical cord veins. The integrity of perfused endothelium was confirmed by morphological and functional criteria. Highly malignant cells in vivo adhered to the endothelial cells, as shown by scanning electron microscopy. The specific attachment of radiolabelled malignant cells to the whole vein was already maximal within 30-60 min and remained stable for perfusion flow rates ranging between 10 and 60 ml/min. It increased proportionally to the number of cells infused and could be modulated by human platelets, human fibronectin and rabbit anti-laminin antibodies. In contrast, the binding of human or rodent non-malignant cells in vivo, of human red blood cells and of human platelets to the endothelial cells was negligible under similar experimental conditions. This perfusion system therefore represents a new model for elucidating some mechanisms involved in tumour cell arrest in vivo.
Cell Adhesion↗
In situ characterization in freeze-fractured mouse thymuses of lymphoepithelial complexes ultrastructurally similar to isolated thymic nurse cells.
Scanning and transmission electron microscopy of the cracked surfaces of cryofractured pre-fixed C57BL/Ka mouse thymus reveals the existence of cell complexes, distinct from the surrounding cell organization, in which groups of lymphocytes are delimited by large cytoplasmic sheets or envelopes. These complexes, located in the subcapsular and cortical regions, display morphological features similar to that of the thymic nurse cells (TNCs), which can be isolated from the mouse or human thymus enzymatically dissociated. They can be considered as dynamic systems able to modify their three-dimensional organization, namely with regard to intrathymic cellular traffic involved in T-lymphocyte maturation.
Animals↗
Target cells and thymus microenvironment in the pathogenesis of thymic lymphomas in C57BL/Ka mice.
In C57BL/Ka mice, the induction of thymic lymphomas either by inoculation of radiation leukemia virus (RadLV) or by a split dose irradiation requires complex cellular events: Target cells are found among the population of thymic subcapsular blast cells, or, alternatively, of marrow or spleen prothymocytes; Progression of target cells to lymphoma growth requires a multi-step process, which occurs only within thymic microenvironment; Target cells are rapidly induced as "preleukemic" cells; After inoculation of RadLV, the initial events occur when target cells are in close association with cells of a specialized component of thymic epithelium, i.e., the so-called "nurse cells"; The leukemogenic agents induce damages to the thymic microenvironment itself; Lymphoma prevention by marrow grafting after irradiation results from mechanisms still unknown which inhibit the progression of "preleukemic" cells to neoplastic growth.
Animals↗
Ultrastructural evidence of the ion-transporting role of the adult and larval neck organ of the marine gymnomeran Cladocera (Crustacea, Branchiopoda).
The neck organ of adult and immature forms of four marine gymnomeran Cladocera species (Podonidae) has been characterized morphologically by light-scanning- and electron microscopy. Although displaying some special features, a comparison with organs assuming a comparable regulating function in other organisms indicates that the neck organ of the adult Podonidae exhibits ultrastructural evidence of involvement in ion-transporting mechanisms. The extensive ventral plasma membrane infoldings closely connected with the chondriom and the peculiar organization of the cuticular site associated with the subjacent apical cell limits of the organ are among the chief structural specializations. The fact that similar structures are already present in the embryonic neck organ confirms previous indirect evidence that podonid embryos can hypo-osmoregulate as soon as the ion concentration of the brood chamber rises to that of the outside medium.
Animals↗
Correlation of alkaline phosphatase activity to normal T-cell differentiation and to radiation leukemia virus-induced preleukemic cells in the C57BL mouse thymus.
Cytochemical methods at the light and electron microscopic level were used to define the pattern of alkaline phosphatase (APase) activity in normal thymus and to study its modifications after inoculation with the thymotropic leukemogenic radiation leukemia virus in correlation with the emergence of preleukemic cells and their thymus dependency. APase was found in numerous lymphoblasts of the fetal thymus. The enzyme was also detected in a few lymphoid blast cells of the normal young adult thymus, which were closely associated with thymic nurse cells. The observed distribution of APase in normal thymus suggests that its expression could be limited to an early stage of the T-cell differentiation pathway. After inoculation with radiation leukemia virus, APase activity remained normal for almost the entire latency period, during which virus replication spread to the cortex and thymus-dependent preleukemic cells appeared. An important increase in the number of APase-positive cells occurred later, i.e., at the end of the latency period, in nontumoral thymus, which displayed lymphocytic depletion and contained autonomous thymus-independent preleukemic cells. These latter features obviously reflected the malignant transformation of thymus lymphoblasts, which eventually led to the development of the thymic lymphomas. The results raise the question of the possible filiation between the thymic nurse cell-associated APase-positive lymphoid cells of the normal thymus and the target cells susceptible to productive infection and to neoplastic transformation after radiation leukemia virus infection.
Alkaline Phosphatase↗
"Thymic nurse cells" contain the first virus producing cells after inoculation of the radiation leukemia virus in C57BL/Ka mice.
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Animals↗
Thymic nurse cells are the first site of virus replication after inoculation of the radiation leukemia virus.
The induction of thymic lymphomas by inoculation of the Radiation Leukemia Virus (RadLV) requires interactions between RadLV, lymphoid cells and thymus microenvironment. The possible localization of this interaction within the peculiar lymphoepithelial complexes called 'thymic nurse cells' (TNCs) has been investigated. Electron microscopic studies, as well as in vitro experiments using a very sensitive infectious centre detection assay demonstrated that most of the first virus producing cells after RadLV inoculation are located within the TNCs. Most of these structures belong to the thymus subcapsular zone. They contain lymphoid cells with the phenotype of the major (cortical) thymocyte population. Data support the view that a limited subpopulation of subcapsular immature thymocyte can act as specific targets for productive infection with RadLV. Furthermore, the initiation of virus replication appears related to the interaction between the immature thymocyte and the 'nurse cells' microenvironment.
Animals↗
Evidence for a particular binding capacity of rat peritoneal macrophages to rat glomerular mesangial cells in vitro.
The adhesion of normal rat peritoneal macrophages to normal rat glomerular epithelial or mesangial cells has been studied in vitro after a 60 min incubation at 37 degree C. After washing, the cell preparations were examined by phase contrast or scanning electron microscopy. Quantitative studies were also performed using macrophages labelled with 99mTc tin colloids. Peritoneal macrophages predominantly adhered to the cultured mesangial cells. The percent-age of labelled macrophages adhering to these cells was about 10 times higher than that of labelled macrophages adhering to the cultured epithelial cells. This percentage increased proportionally to the number of labelled macrophages added, and was strongly reduced by the prior incubation of macrophagic cells with aggregated IgG, with anti-fibronectin IgG, or with F(ab')2 fragments of anti-fibronectin IgG. Furthermore, the macrophage-mesangial cell interaction was significantly reduced by the prior incubation of mesangial cells with anti-fibronectin IgG or with F(ab')2 fragments of anti-fibronectin IgG. The data demonstrate that normal rat peritoneal macrophages preferentially adhere in vitro to normal rat glomerular mesangial cells, and that this binding may be modulated, at least, by: (a) the Fc receptor binding activity of macrophages; (b) the fibronectin molecules available at the surface of macrophages and of mesangial cells.
Animals↗
Thymic microenvironment and cultures derived from mouse thymic explants. A morphological study.
Cultures derived from thymus fragments of embryonic (18-19 day old), newborn or one month old C57BL mice have been characterized functionally l(phagocytic and nonspecific esterase activities) and morphologically by means of light, scanning (SEM) and transmission (TEM) electron microscopy. The observations show the heterogeneity of the cell populations composing the monolayers. After a few days incubation macrophages appear as the predominating cell type, while epithelial cells usually constitute no more than 30% of the cells. Experiments designed to determine the fate of lymphocytes adhering to the monolayers lead us to believe (on the basis of SEM morphometric analysis) that the survival of lymphocytes attached either to thymic macrophages or to epithelial cells is improved during the first days of coculture. This survival enhancement does not, however, appear to be a specific inductive effect since a similar survival increase is found when lymphocytes adhere to non-thymic cells. In contrast with the monolayer, the explant provides a three-dimensional culture system able to preserve intact thymic microenvironmental conditions since numerous lymphocytes are found even in five week old cultures which were not overlaid with thymocytes or spleen cells.
Animals↗
Isolation and characterization of rat renal glomerular cells in vitro.
Glomerular tufts were isolated from normal rat kidneys and were cultivated in RPMI 1640 medium supplemented with 15% fetal bovine serum. Studies on DNA synthesis demonstrated two peaks (A and B) of cell division. The cells of peak A grew as a monolayer until confluency, exhibited many junctional complexes and microvilli. They were very susceptible to the aminonucleoside of puromycin, as glomerular epithelial cells in vivo. They did not contain many bundles of intracellular microfilaments and were not stained by an anti-factor VIII serum. The cells of peak B formed both monolayered sheets and multilayered bands, exhibited no junctional complexes, but contained large bundles of intracellular fibrillar structures, which were strongly stained by an antimyosin antiserum. They were not stained by an anti-factor VIII antiserum. The B cells exhibited a contractile activity in response to 10(-9) M angiotensin II and were very susceptible to mitomycin C treatment, as glomerular mesangial cells in vivo. They synthesized large amounts of prostaglandins (mainly PGE2). The data suggest that the A cells are visceral epithelial cells, and that the B cells are smooth muscle-like cells derived from the glomerular mesangium.
Angiotensin II↗
Ultrastructural and functional characteristics of the cell populations composing the cultures derived from mouse thymic explants.
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Animals↗
Calcium-binding sites as determined by electron microscope X-ray microanalysis in the electrocytes of the electric organ of Torpedo marmorata.
Application of the Oschman and Wall technique to slices of non-stimulated electric organs of Torpedo marmorata reveals electron-dense deposits along the uninnervated and innervated membranes and in mitochondria of the electrocytes as well as in synaptic vesicles of the nerve terminals. As identified by X-ray microprobe analysis, the area containing these deposits reveal higher concentrations of calcium than the other probed regions in which they are lacking. The deposits generally occur in the form of rounded corpuscles, of about 10--20 nm in diameter in the plasma membranes to 30 nm in synaptic vesicles. In mitochondria, they can reach 100 nm or more. These results are briefly discussed with regard to previous data concerning calcium involvement in cholinergic transmission and its possible role in ionic regulation of the electrocyte.
Animals↗
Ultrastructural features and glycogen distribution in the electric organ of the electric ray Torpedo marmorata L.
The ultrastructural topography of glycogen in the electic organ of the fish Torpedo marmorata has been examined following Thiéry's method and the modified osmium tetroxide post-fixation of De Bruijn. Both methods reveal a high concentration of glycogen particles in the nerve terminals, particularly in pedunculate pouches issuing from the nerve endings and bulging into the intersyncytial area. A few sparse positive particles are scattered at random in the Schwann cells and in the cuff cells occasionally encapsulating the myelinated and ummyelinated subsynaptic axons. In the electric cell, glycogen occurs in the form of scattered particles homogenously distributed among all the cytoplasm. The structure and the size of glycogen granules in relation to the detection methods used and to previous parallel investigations are briefly discussed.
Animals↗
On ultrastructure of the trabeculae in the interlamellar membranes of nacre conchiolin of the Nautilus shell.
The ultrastructure of the interlamellar and intercrystalline membranes of nacre conchiolin of Nautilus has been studied on shadow-cast preparations and on ultrathin sections after various fixation and/or decalcification procedures. After immersion in osmium tetroxyde, glutaraldehyde, EDTA, ascorbic acid and CPC solutions, the nautiloid pattern of conchiolin structure (sturdy trabeculae, elongated fenestration) was observed in all samples. The representative ultrastructure of the sectioned trabeculae was composed of micro-meshworks. Microfibrils were not found. In contrast with the other substance, chromium sulphate produces a shrinkage of the nautiloid pattern into continuous rug-like membranes. In the sections, a distinct condensation of the micro-meshworks occurs at the periphery of both interlamellar and intercrystalline membranes. These observations are discussed namely in relation to the problem of structural identification of the EDTA soluble fraction of the nacre conchiolin.
Animals↗
Coagulocyte alterations in clotting hemolymph of Carausius morosus L.
1. The structural changes in the coagulocytes of Carausius morosus during hemolymph coagulation in vitro have been studied under the PCM and in the TEM. 2. In agreement with former PCM observations on Carausius morosus, the coagulocytes are the only hemocytes to induce coagulation of the plasma. Immediately or after a few seconds upon withdrawal of the hemolymph, their structural changes consist of a considerable enlargement of the perinuclear cysterna and of direct ejection into the plasma of nuclear and cytoplasmic substances through microruptures of the cytoplasmic membrane. The other categories of hemocytes do not contribute to the plasma coagulation. Their structural alterations take place without breakage of the cytoplasmic membrane when the plasma reactions are already established. 4. These plasma reactions appear in the form of circular islands of granular material around the coagulocytes, of extension of the coagulum in the channels between the islands and of transformation of the clot into a network of threads. 5. As reported in other studies in the TEM, no specific organelle characteristic of the coagulocyte ultrastructure could be found in the coagulocytes of Carausius. 6. Owing to the absence of any specific structural criterion of identification, the results suggest that the functional difference between coagulocytes and the other categories of hemocytes as regards coagulation of the plasma might be caused in part by differences of permeability of the cell membranes.
Animals↗
The basement membrane proteins laminin and type IV collagen in isolated villi in pre-eclampsia.
The distribution and concentrations of the basement membrane proteins laminin and type IV collagen were studied in isolated placental villi in normal pregnancy and in pre-eclampsia. In both cases these proteins could be localized by immunofluorescence in the trophoblast and capillary basement membranes, and occasionally also in the matrix surrounding the capillaries. The basement membrane proteins were quantified by solubilizing the villi with proteolytic enzymes and by subsequently measuring the concentrations of two resistant domains of these proteins (7-S collagen and the fragment PI, representing type IV collagen and laminin, respectively) with specific radioimmunoassays. The ratio type IV collagen:laminin was significantly higher in pre-eclamptic samples than in the controls, most probably reflecting a decrease in laminin concentration in the villi in pre-eclampsia. Such a change in the chemical composition of placental basement membranes could weaken the attachment of trophoblast cells to the underlying basement membrane and also modify the permeability and exchange properties of the villi.
Basement Membrane↗