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Biomedical subjects

D Ribatti

Publications and source records attributed to D Ribatti.

At least 145 records · Page 8Linked to original sources
PubMed1994

Bone marrow angiogenesis and progression in multiple myeloma.

Tumour growth is angiogenesis-dependent. We found a high correlation between the extent of bone marrow angiogenesis, evaluated as microvessel area, and the proliferating (S-phase) fraction of marrow plasma cells, evaluated as labelling index (LI), in patients with multiple myeloma (MM) and in those with monoclonal gammopathies of undetermined significance (MGUS). Angiogenesis itself was significantly associated with active as opposed to non-active MM and MGUS. The highest microvessel area accompanied rapidly progressive MM with the highest LI. When a cut-off value of 2% or greater of the microvessel area was used, most patients with active MM were classified correctly. The risk of active disease in patients with MM increased in parallel with the microvessel area. A causal relationship between plasma cell growth, activity phase in MM and marrow angiogenesis is suggested. Since angiogenesis proceeds in step with the enlargement of plasma cell tumours and the activity phase in MM, its measurement could be a useful prognostic marker in patients with plasma cell proliferative disorders.

Aged↗
PubMed1994

Differential expression of two ICAM-1 epitopes and LFA-1 chains in B-cell non-Hodgkin's lymphomas.

B-cell non-Hodgkin's lymphomas (B-NHL) and B-cell areas of reactive lymphadenopathies were investigated immunohistochemically for expression of two distinct ICAM-1 epitopes, Me14/D12 and P3-58, and the LFA-1 alpha and beta chains. Partial or total loss of expression of one or both epitope(s) and/or chain(s) was evident in all B-NHL in function of increasing Working Formulation (WF) malignancy grade, with most defects in the high-grade tumors, namely the lowest detectability of the ICAM-1 Me14/D12 and LFA-1 alpha chain, the lowest co-expression of ICAM-1 epitopes and LFA-1 chains, and the most frequent simultaneous loss. The ICAM-1 and LFA-1 profiles overlapped within the low- and intermediate-grades, whereas striking differences between the high-grade subtypes were detected. Specifically, Burkitt's and lymphoblastic tumors always lost both epitopes and both chains. Large cell, immunoblastic tumors occasionally did so, and also showed either uncoordinated expression or co-expression of these constituents. It is suggested that expression defects of this type may help differentiate malignant from benign lymphoproliferations, and also be involved in the progression of B-NHL, since most are observed in high-grade tumors, whose ICAM-1 and LFA-1 profiles indicate that their subtypes are the expression of distinct normal B-cell differentiation stages.

Antibodies, Monoclonal↗
PubMed1994

Reorganization of blood vessels after their partial section in the chick embryo chorioallantoic membrane.

In this study the sequence of vascular reorganization of the vascular network after partial section of a branch of the left chorioallantoic artery is described in the chick embryo chorioallantoic membrane. After several house (24-72), the defect of the artery is consistently bypassed by a collateral interconnecting of the stumps of the damaged vessel in such a way as to re-establish its continuity, according to a precise scheme which was similar in all cases that underwent the same type of ablation.

Allantois↗
PubMed1994

Orthogonal arrays of particles (OAPs) in perivascular astrocytes and tight junctions in endothelial cells. A comparative study in developing and adult brain microvessels.

The plasmamembranes of the astrocyte processes, which envelop the capillaries of the adult brain, contributing to the blood-brain barrier constitution, are characterized by peculiar aggregates of intramembrane particles (IMPs) packed in orthogonal arrays (orthogonal arrays of particles, OAPs). With the aim of investigating the maturation sequence of the cerebral microvasculature, the IMPs distribution has been analysed in the plasmamembranes of both perivascular astrocytes and endothelial cells of fractured microvessels, in 16-, 20-, 21-day chick embryo and 10-day chicken optic tecta. The IMPs distribution undergoes remarkable changes from late embryonic to early postnatal life in the astrocytes and endothelial cells as well. In the astrocyte plasmamembranes, short chains of individual particles and linear units of packed ones precede the appearance of complete OAPs; in the endothelium junctional plasmamembranes, fibrils of fused particles precede the formation of fibrillary networks which express the tight junction setting up. The parallel formation of the astrocytic OAPs and the endothelial tight junctions further supports the suggestion that mutual relationships establish between perivascular glia and endothelium in the cerebral microvasculature differentiation during the blood-brain barrier development.

Animals↗
PubMed1993

Melanocyte tumor progression is associated with changes in angiogenesis and expression of the 67-kilodalton laminin receptor.

BACKGROUND: A number of experimental studies have substantiated changes in angiogenesis and in laminin/laminin-receptor interactions during tumorigenesis and tumor progression. However, these observations have never been verified objectively in tissues from a well-defined model of tumor progression. METHODS: Tissues from 97 proliferative lesions of the melanocyte lineage defining distinct steps in tumor progression were investigated immunohistochemically for changes in angiogenesis and expression of the laminin receptor (67-kilodalton molecule). RESULTS: Although the microvessel number was low in common nevi, it increased significantly in nevi with architectural disorder with varying degrees of melanocytic atypia (termed "nevi with ADMA"), and these changes persisted during transformation. Progression to primary melanomas was accompanied by a high microvessel number and progression to metastases by another significant increase. The number and diameter of microvessels were significantly higher at the lesion base than at the adjacent dermis of primary melanomas and higher in the lesion than in the adjacent tissue of metastatic foci. Expression of the laminin receptor, evaluated as percentages of positive lesions and positive cells per lesion, underwent upregulation in the course of progression. Changes in expression were associated mostly with nevi with ADMA, transformation, and deepening of the tumors into the dermis. CONCLUSIONS: These in situ data suggest that more frequent interactions between melanocytic cells and their microvasculature via adhesion protein laminin occur during tumor progression.

Adult↗
PubMed1993

Perivascular astrocytes and endothelium in the development of the blood-brain barrier in the optic tectum of the chick embryo.

The role played by perivascular astrocytes in neural vessel maturation was investigated in microvessels of the chick embryo optic tectum. Three-dimensional reconstructions and quantitative analyses were made, and permeability was studied. On embryonic days 14-16, 12.5% of the microvessel wall is surrounded by astrocyte endfeet which, in most cases (82%), are located under endothelium junctions; the latter, at this stage, partly prevent the extravascular escape of the marker horseradish peroxidase. On days 18-21, the astrocyte processes form a nearly complete perivascular sheath enveloping 96% of the microvessel perimeter; the junctions of the endothelial cells are much wider and impermeable owing to extensive fusion of the endothelial plasma membranes. This investigation suggests a close relationship between the perivascular arrangement of glia and differentiation of the endothelium tight junctions and indicates that the morphofunctional maturation of the latter takes place progressively during the prenatal organogenesis of the chick central nervous system.

Animals↗
PubMed1993

The development of the blood-brain barrier in the chick. Studies with evans blue and horseradish peroxidase.

The development of the blood-brain barrier was microscopically examined in the optic tectum of the chick. The permeability of neural vessels to Evans blue and horseradish peroxidase decreases progressively during the period of incubation. Diffusion is massive on the 6th and 10th days of incubation and is reduced on the 14th day; on the 18th-21st day of incubation the vascular walls still allow Evans blue to diffuse but prevent extravasation of horseradish peroxidase completely. In one month old chickens the nervous substrate is free of both tracers.

Animals↗
PubMed1992

Mast cell populations in the chick embryo lung and their response to compound 48/80 and dexamethasone.

Two mast cell populations, connective tissue mast cells (CTMCs) and mucosal mast cells, (MMCs) containing different proteoglycans in their granules, can be distinguished in several animal species by means of histochemical methods. In this study we documented the presence of these two types of mast cell in the chick embryo lung, from the 15th incubation day for the MMCs, and from the 18th incubation day for the CTMCs. Lungs of embryos treated with compound 48/80, which produces degranulation of the CTMCs, showed a decrease in the number of this type of mast cell and an unchanged number of MMCs. In the lungs of embryos treated with dexamethasone, which degranulates MMCs, a reduction in the number of these cells and an unchanged number of the CTMs were found.

Animals↗
PubMed1992

GFAP-immunoreactive perivascular glia in the chick optic tectum.

Immunocytochemical staining of the glial fibrillary acidic protein (GFAP) was utilized to characterize the processes of the astrocytes enveloping the vessel wall in the central nervous system. The study was carried out in the mesencephalic lobes of 18 and 20 incubation-day chick embryos and of 20 day chickens. A perivascular GFAP positivity was mainly detectable in the vessel portions running within the tectum white layers, while it was scarce, or absent, in the grey ones. The perivascular GFAP negativity in the tectum cellular layers was not considered result of the absence of astrocytic endfeet since our previous electronmicroscopical studies evidenced an almost complete perivascular astrocytic ring throughout the tectum layers at hatching time. Present data rather suggest that the expression of the GFAP-made intermediate filaments in developing astrocytes might be controlled by the surrounding microenvironment.

Animals↗
PubMed1992

Permeability-related structures in developing and mature microvessels of the chicken optic tectum.

The mode and the temporal sequence of the modifications undergone by permeability-related structures in the neural microvessels have been ultrastructurally and morphometrically investigated in optic tecta of 6, 14, and 18 incubation day (i.d.) chicken embryos and of 30 day chickens. Horseradish peroxidase was utilized as a permeability marker. The endo- and exocytosis-related structures (vesicles and vacuoles) and the interendothelial junctions remarkably change during development: the density of the vacuoles is decreased at the 14th i.d., while that of the vesicles becomes significantly low at the 18th i.d., both reaching lowest values in the chicken; the passage of the marker through the endothelial junctions begins to be hindered from the 14th i.d., parallel to the perivascular arrangement of astrocytic glia endfeet, and it is completely blocked at hatching time. The findings suggest that the optic tectum microvessels are permeable, and thus immature, in the early development and progressively acquire morphofunctional features of vessels provided with barrier devices during the pre- and post-natal development of the brain.

Animals↗
PubMed1992

Tight endothelial junctions in the developing microvasculature: a thin section and freeze-fracture study in the chick embryo optic tectum.

The development of the interendothelial tight junctions was studied in the microvessels of the otpic tectum of chick embryos, at the 14th-16th and 18th-20th incubation day (i.d.), and in post-hatching chickens, using thin sections and freeze-fracture techniques. At the 14th-16th i.d., the junctional plasmamembranes of the endothelial cells are simply apposed or fused for brief tracts showing a pentalaminar or trilaminar configuration. In the replicas the P-faces of the fractured junctional membranes are either lacking in intramembrane particles (IMPs) and characterized by finger-like depressions, or provided with discrete IMPs aligned in rows. At the 18th-20th i.d., the thin peripheral expansions of the endothelial cells are superimposed and welded by continuous pentalaminar junctions. Their fracture P-faces display junctional strands formed by parallel fibrils of fused IMPs, with or without interconnections. In the 10-day-old chickens the junctions consist of highly complex networks of fibrils. The results have made it possible to recognize precise relationships between the features of the developing endothelial junctions in the ultrathin sections and, respectively, in the replicas. Moreover, the observations suggest that tight junction formation occurs progressively in the cerebral microvessels by processes of alignment and fusion of the IMPs, which conclude with the arrangement of fibrils in networks.

Animals↗
PubMed1991

Lymphocyte-induced angiogenesis: a morphometric study in the chick embryo chorioallantoic membrane.

A morphometric analysis was carried out on the chorioallantoic membrane (CAM) vasculature in chicken embryos treated (1) with phytohemagglutinin (PHA), (2) with supernatants of cell cultures of normal human T lymphocytes and (3) of T lymphocytes stimulated with PHA in order to evaluate their angiogenic properties. In the left chorioallantoic artery, the number of primary collaterals, and the number and length of secondary and tertiary collaterals were measured. In the series treated applying procedures 1 and 3, the mean value of the total number of all the collaterals was higher than that of the normal-developing CAM vessels, while the length of the secondary and tertiary collaterals was lower than that of the normal-developing blood vessels. In the series treated following procedure 2, no statistically significant differences were observed between experimental and control series in any parameters evaluated. The possible significances of these morphological findings are discussed with reference to the angiogenic roles played by human T lymphocytes, probably determined by lymphokines released after the activation of these cells by PHA, and by PHA alone, probably dependent on its aspecific mitotic activity.

Adult↗
PubMed1991

[History of immunologic deficiency].

The description of agammaglobulinemia by O. Bruton in 1952 and later clinical studies by R. Good preceeded by sporadic clinical observations on deficits in the immune function associated with hyponutrition, nephrosis and tumors or with inborn errors of metabolism have all made their contribution to the emerging of the concept of immunological deficiency diseases. The clinical-pathogenetic description of immunological deficiency diseases has played a fundamental role in the understanding of the anatomo-functional bases of the immune system and research work on the phylogenetic and ontogenetic evolution of the immune response. Various methodologies, from the idea of experimentum naturae to molecular pathology, combine to define and direct this research, the result of an ongoing interaction between the hospital and the laboratory. This leads to a necessary theoretical-practical synthesis and contributes to the consolidation of an immunologically-directed medicine.

Adolescent↗
PubMed1991

The effects of long-term hypoxia on epicardium and myocardium in developing chick embryo hearts.

The consequences of long-term O2 deprivation on heart development were analyzed morphometrically and ultrastructurally, utilizing the hearts of chicken embryos developed under hypoxia from the 3rd to the 18th incubation day. The results indicate that embryos kept under low O2 blood tension do not show disturbances in heart morphohistogenesis, but are characterized by a thicker epicardium and a thinner myocardium than the controls; moreover, both the number and calibre of the heart microvessels are increased. The thickening of the epicardium is due to hyperplasia of the mesothelial cells, increment in calibre of the submesothelial vessels, and to conspicuous perivascular infiltration of blood-derived cells. The thinning of the cardiac muscle seems to be dependent on myocardiocyte hypotrophy and myofibril reduction. The increase in the volume density of myocardium vessels, due to their dilatation and proliferation, may be considered expression of a vascular adaptive reaction to low oxygen tissue concentration.

Animals↗
PubMed1991

[Changes in the subendothelial compartment during the maturation process of cerebral microvessels].

Basement lamina and pericytes of growing blood microvessels were analyzed in the chick embryo optic tectum, from the 8th incubation day to hatching. Formation of the basement lamina and morphological changes of the pericytes take place in a short range of time, but late in the embryonic life, when also the blood brain barrier (bbb) devices are developing. The spatial and temporal coincidence between basement lamina formation, endothelium tight junction differentiation, and perivascular arrangement of the astrocytic glia, indicates that these events are correlated and corroborates the hypothesis that the glia needs an extracellular matrix to induce the junctional system maturation in the neural endothelia. Pericytes are irregular in shape during the early neural angiogenesis and smooth and flattened later, as the basement lamina synthesis is taking place; these cells represent a second line of barrier beyond the endothelium when the bbb is immature, owing to their phagocytic and digestive properties.

Animals↗