PubMed Health⌕ Search

Biomedical subjects

M T Pieraggi

Publications and source records attributed to M T Pieraggi.

At least 19 recordsLinked to original sources
PubMed1992

Oxidized low density lipoproteins elicit DNA fragmentation of cultured lymphoblastoid cells.

Lymphoblastoid cell lines continuously pulsed with mildly oxidized low density lipoproteins, exhibited a significant increase of DNA fragmentation induced by oxidized LDL internalized by cells. DNA fragmentation was associated with an increasing number of morphologically characteristic apoptotic cells simultaneously with the increase of cytotoxicity indexes, and the activation of the poly(ADP-ribose) polymerase, a nuclear enzyme stimulated by DNA strand breaks. The potential involvement of these biochemical and morphological changes in atherogenesis is discussed.

B-Lymphocytes↗
PubMed1992

A delayed and sustained rise of cytosolic calcium is elicited by oxidized LDL in cultured bovine aortic endothelial cells.

Bovine aortic endothelial cells (BAEC) pulsed for 5 h with mildly oxidized low density lipoproteins (LDL), exhibited a broad, sustained and high peak of [Ca2+]i occurring several hours after the end of the pulse and reaching very high [Ca2+]i values (around 2500-3000 nmol/l) and a concomitant drop of cytosolic pH (around 0.2-0.3 pH units) without any loss of cell viability. When BAEC were continuously pulsed with oxidized LDL, the peak of [Ca2+]i was more sustained than in short pulse experiments and was associated with irreversible morphological changes usually associated with cytotoxic events (blebbing) and with a marked loss of viability. The potential involvement of these biochemical and morphological changes in atherogenesis are discussed.

Animals↗
PubMed1992

Phase transitions and chain dynamics, in the solid state, of a pentapeptide sequence of elastins.

Differential scanning calorimetry (d.s.c.) and thermally stimulated current (t.s.c.) have been applied to the study of thermal transitions and dielectric relaxations of a pentapeptide sequence: Gly-Leu-Gly-Gly-Val of elastin. The manifestation of the glass transition has been observed by both techniques. The analysis of the fine structure of t.s.c. spectra reveals the existence of local order in the amorphous phase upon physical ageing. In the 'true' amorphous phase, cooperative motions of sequences of various length are observed. The corresponding activation parameters are characteristic of the 'structure' of the amorphous phase and might be used as reference for further studies.

Amino Acid Sequence↗
PubMed1992

Optimization of a model of full-thickness epidermal burns in the pig and immunohistochemical study of epidermodermal junction regeneration during burn healing.

In order to obtain a wound model in which healing involved epidermis rebuilding and epidermodermal junction (EDJ) regeneration without involvement of any dermal repair, we optimized a previous model of experimental cutaneous burning with an aluminum bar by testing various conditions of burning associated with different pre- and postburn skin treatments. On the optimized model of full-thickness epidermal burns without any dermal injury, we investigated the kinetics of regeneration of 4 EDJ components, from day 2 to day 23 after burning. The epidermal healing was studied by light microscopy and EDJ regeneration by indirect immunofluorescence with one bullous pemphigoid (BP) serum, antisera to fibronectin and to type IV collagen (Coll IV) and the monoclonal antibody 4C 12-8 to laminin. Histologically, neoepidermis, detected from day 2, appeared as a reepidermization tongue which progressed from the burn edges between the overlying necrotic burned epidermis and the underlying uninjured dermis. Epidermis continuity was found to be restored at day 9. Immunohistochemically, labelling of BP antigen (BPA), Coll IV and laminin extended all along the neo-EDJ, from day 2 to day 23. In contrast, fibronectin labelling was detected only in the proximal and median portions of the neo-EDJ before day 7, then all along the neo-EDJ, from day 7 to day 23. For all the components except Coll IV, the intensity of the labelling beneath the neoepidermis was higher than that of the residual labelling remaining under the necrotic epidermis. Therefore, BPA and laminin regenerated synchronously to neoepidermis whereas fibronectin first regenerated with delay, then synchronously.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Non-atherosclerotic aorta in Cynomolgus after a hypercholesterolemic regimen].

The authors present a study on atherosclerotic and non atherosclerotic lesions of aortas of Cynomolgus (Macaca Fascicularis) on high fat diet (HFD) (6-12-24 months), after regression and after resumption. At 6 months 2 aortic responses are seen: an edema, deep and superficial clumps of foam cells, few synthetic smooth muscle cells (SSMC) few collagenic fibers--an edema, few superficial foam cells, many SSMC, secreting collagen and elastin. At 12-24 months, after regression and resumption, two aortic lesions are observed: a pronounced atheroma (47 animals) and no atheroma (14 animals). In this case, in the inner part of the aortic wall there are a fibrosis and an elastogenesis, SSMC and just some superficial lipids deposits. These aortic responses of SSMC are certainly the consequence of the environment (the diet) but also the possible consequence of the genetic determinism of SSMC since some animals only present this early, constant fibro-elastic response during this experimental follow up even though all the animals have been subjected to the same lipidic stress.

Animals↗
PubMed1991

Healing of full-thickness cutaneous wounds in the pig. I. Immunohistochemical study of epidermo-dermal junction regeneration.

In order to determine the kinetics of epidermo-dermal junction (EDJ) regeneration during would healing, we studied the regeneration of five EDJ components during reepidermization. Cutaneous wounds (50-mm length, 2-mm width, and 5-mm depth) were produced on the flank area of two pigs and left unsutured. Daily biopsies from day 1 to day 20 were studied by light microscopy on paraffin-embedded sections and by indirect immunofluorescence on cryostat sections using human sera to bullous pemphigoid antigen (BPA) with specificity previously confirmed by indirect immuno-electron microscopy, rabbit antisera to type IV collagen (Coll IV) and to fibronectin, and the monoclonal antibodies (MoAb) 4C 12-8 to laminin and NP-76 to type VII collagen (Coll VII). Histologically, reepidermization started from day 1 and progressed unidirectionally and exclusively from the wound edges. Up to day 9, the distal tips of the neo-epidermal tongues generally extended between the crust and the granulation tissue (GT). They fused on day 10, restoring epidermal continuity. For each EDJ component, the date of appearance (emergence), the spreading under the neo-epidermis tongue (expression), and the morphologic aspect of the labeling were studied. BPA and Coll IV were detected from day 1 to day 20 and found to be expressed all along the neo-EDJ. Fibronectin and laminin were detected from day 1, were present in the proximal and median zones of the neo-EDJ before day 7, up to the distal tip from day 7 to day 9 and were all along the neo-EDJ from day 10 to day 20. Coll VII was only detected from day 3. It was present in the proximal zone on day 3 and day 4, in the proximal and median zones on day 5 and day 6, than all along the neo-EDJ from day 7 to day 20. From day 10, all the labeling characteristics of the five components were found to be similar in the neo-EDJ and in the normal EDJ. With regard to the neo-epidermis progression, we found a synchronism of emergence and expression for BPA and Coll IV, a synchronism of emergence but a delay of expression for fibronectin and laminin and lastly, a delay of emergence and expression for Coll VII. We concluded that BPA and Coll IV could constitute the framework on which the neo-EDJ is progressively built by adjunction of the other components, restitution being obtained just after epidermal continuity is restored.

Animals↗
PubMed1990

Ultraviolet-treated lipoproteins as a model system for the study of the biological effects of lipid peroxides on cultured cells. II. Uptake and cytotoxicity of ultraviolet-treated LDL on lymphoid cell lines.

The 'cytotoxicity' of ultraviolet-treated low-density lipoproteins (LDL) has been investigated using cultured lymphoid cell lines from normal subjects and from a patient with receptor-negative familial hypercholesterolemia. The ultraviolet-treated LDL were taken up by control lymphoblasts through the classical apo B/E-receptor pathway, while they were slowly taken up by receptor-negative lymphoblasts by non-specific endocytosis. These LDL were found highly 'cytotoxic' on normal lymphoblasts as demonstrated by Trypan blue dye uptake, [3H]thymidine incorporation, lactate dehydrogenase release and by electron microscopy. The 'cytotoxicity' increased progressively with the concentration of ultraviolet-treated LDL in the culture medium and with the incubation time. In contrast, lymphoblasts from familial hypercholesterolemia were not sensitive to low doses of ultraviolet-treated LDL (up to 150 micrograms apo-B/ml). The comparison of cells from normals and familial hypercholesterolemia showed that the 'cytotoxic' effect occurred subsequently to the LDL uptake, either receptor-mediated or receptor-independent. Experiments combining short-time (5 h) pulse with ultraviolet-treated LDL (labelled with [3H]cholesteryl oleyl ether) and a relatively long-chase period (72 h) showed: (1) a relationship between the delay for the appearance of the 'cytotoxicity' and the amount of ultraviolet-treated LDL taken up by the cells; and (2) the existence of a minimal dose (threshold dose) for triggering the 'cytotoxic' effect. The use of 'hybrid' LDL, prepared by partial delipidation of non-treated LDL and reconstitution by re-incorporating the neutral lipid fractions isolated from ultraviolet-treated LDL, demonstrated that the 'cytotoxic' effect is mainly mediated by triacylglycerols and cholesteryl esters. Scanning electron microscopy showed that the most prominent morphological change resulting from the uptake of ultraviolet-treated LDL was the early blebbing of plasma membranes.

Biological Transport↗
PubMed1990

Age-related changes in the elastic tissue of the human thoracic aorta.

Thirty human aortas with varying degrees of atheroma graded macroscopically according to the WHO classification were taken at autopsy from subjects of different ages (24-86 years). Study by light microscopy showed aortas with an intact wall (4 subjects, 25-46 years) with a thin intima and regular elastic layers, and aortas with varying degrees of modification of the wall, where the intima was of varying thickness and the elastic fibers showed varying degrees of damage (moderate lesions: 5 subjects, 35-52 yrs; severe lesions: 21 subjects, 26-86 yrs). From each aorta, a 4-cm segment from the tunica media, free of atheromatous lesions, was defatted and subjected to successive treatment with EDTA-Tris, 6 M guanidine-HCl-Tris, 6 M guanidine-HCl-Tris-DTE and collagenase. The residues (EP residues) were subjected to amino acid (AA) analysis and transmission electron microscopy (TEM) study. In the young subject, the AA composition was similar to that of elastin and the TEM images were characteristic of this substance. In the aging subject, an increase in polar AA and a parallel decrease in apolar AA and crosslinks was noted. By TEM, the elastin was seen to be associated with abundant fibrillar material. Trypsin treatment of EP residues gave E residues, whose composition and TEM appearance were similar in all samples, corresponding to the standard composition of elastin and its classic appearance by electron microscopy. We suggest that the fibrillar material removed by trypsin is the morphological reflection of the chemical variations observed in the EP residues. These correspond to contamination of the elastin by a polar protein fraction. This contamination is closely correlated with age but not with the degree of atheroma. Thus the age-related chemical changes in elastin appear to be independent of the onset and evolution of atheromatous lesions. The 10-15 nm diameter of the contaminating fibrillar material suggests that may be the microfibrillar fraction of elastic tissue.

Adult↗
PubMed1989

[Experimental atherogenesis: early wall changes in the cynomolgus monkey].

The early parietal changes in atherogenesis are characterized by: Increase of endothelial permeability with proteoglycans and L.D.L. storage. Lysis of internal elastic lamellae. Penetration into sub-endothelial space of monocytes macrophages and transformation into foam cells. Parietal fibrosis and proliferating smooth muscle cells play a role in the extension of lipid deposit.

Animals↗
PubMed1988

The elastic tissue of the skin. A comparison of spontaneous and actinic (solar) aging.

In order to separate the changes of actinic damage from those of simple aging, we studied the elastic fibers in low and high sun-exposed skins of normal subjects at different ages. Low sun-exposed skin shows chronologic aging lesions only. These begin at age 30 with a disappearance of oxytalan fibers and with some abnormalities in the reticular and deep dermis; at age 40, aging changes are established: no oxytalan fibers, marked abnormalities, and lysis of elaunic and elastic fibers. In high sun-exposed skin, age-related lesions also occur but are associated with more or less precocious elastotic degeneration in reticular and deep dermis. Both types of aging fibers are revealed by the antielastin antibody HB 8, disappear with elastase, but resist collagenase. Actinic elastosis clearly originates from elastin. The two types of change differ in electron microscopic appearance: with spontaneous aging, elastic fibers are disintegrated (loose and porous fibers); in actinic damage, elastotic fibers are thicker and have accentuated microfibril dense masses. The age-associated lesions could be due to the activity of protease of fibroblastic origin whereas the elastotic degeneration is probably due to the actinic stimulation of fibroblasts.

Adult↗
PubMed1987

[Repair of the connective tissue in a non-sutured skin wound].

During the healing of a second intention wound, granulation tissue is built up during the inflammatory and detersive phase which commences in the wound edges as soon as the loss of substance is created. Granulation tissue becomes scar tissue via connective and vascular proliferation and epidermization takes place concurrently. The origin of the fibroblasts composing the granulation tissue is debated: monocytes or fibroblasts from the wound edges? Ultrastructural and immunohistochemical data from studies of experimental wounds in the pig and the monkey make it possible to determine their origin and follow their progress. These cells originate from the fibroblasts of the wound edges and become undifferentiated cells which multiply and migrate to reach the loss of substance. There they become activated fibroblasts and contribute to repairing the loss of substance by secreting fibronectin and type I and type III collagen. As differentiated fibroblasts and myofibroblasts, they remodel and contract scar tissue.

Acute-Phase Reaction↗
PubMed1979

Fine structural evidence of increased endothelial permeability in chronic lathyrism.

The endothelium of the thoracic aorta of Wistar rats intoxicated with Beta-Aminopropionitrile (BAPN) for 9 weeks was studied. The animals were sacrificed at intervals, from the first to the 9th week of the treatment and 1, 2 and 3 months after the end of the treatment. Changes in the endothelial cells were studied by electron microscopy after staining with uranyl acetate and lead citrate, after impregnation with lanthanum. BAPN increased endothelial permeability, pinocytosis was more active in treated rats than controls, the intercellular junctions widened and cytoplasmic lesions with cell necrosis occurred. These intimal changes were comparable to those observed in man during ageing and in arteriosclerosis.

Animals↗