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L Roncali

Publications and source records attributed to L Roncali.

At least 73 records · Page 4Linked to original sources
PubMed1997

Developmental study of ultrastructural and biochemical changes in isolated chick brain microvessels.

The morphology of the endothelial junctions, the expression of the alkaline phosphatase (ALKP) and gamma-glutamyltranspeptidase (GGT) activities, and the transport systems for neutral amino acids (NAA) and for d-glucose were studied in parallel in isolated microvessels from the brains of 9-, 12-, and 21-day chick embryos and 30-day chickens using freeze-fracturing and biochemical techniques. In the 9-day embryos, the endothelium junctional plasma membranes show alignments of discrete intramembrane particles (Imps) on the replica P-faces. In the 12-day embryos, the junctional membranes show short fibrils of loosely interconnected fused Imps. In the 21-day embryos, the junction is characterized by simple networks, and in the 30-day chickens, by very dense meshworks of continuous, fibrillary strands. In early embryonic life, the ALKP activity is expressed at high levels, more markedly in the microvessels than in the whole brain. ALKP progressively declines in later embryos and even more in adulthood, when the activity is fivefold higher in the microvessels than in the whole brain. No GGT activity is expressed in either embryonic or adult microvessels. The transport systems for NAA and for d-glucose are most active in 12-day embryonic microvessels, and progressively less expressed by the 21st day and in the adult. The results taken as a whole suggest a close relationship between the morphological and the metabolic maturation of the endothelial barrier of cerebral vessels.

Alkaline Phosphatase↗
PubMed1997

Exogenous heparin induces fibronectin overexpression parallel to angiogenesis in the extracellular matrix of the chick embryo chorioallantoic membrane.

Heparin (HE) was injected into the allantoic sac of chick embryo eggs on the 5th day of incubation. After 48 h, a morphometric analysis of angiogenic response and an immunohistochemical investigation of fibronectin (FN) and type IV collagen immunoreactivity in developing vasculature were performed in order to verify whether HE-related choriollantoic membrane (CAM) angiogenic activity was associated with overexpression of FN and/or type IV collagen changes in CAM extracellular matrix. Data to be presented show a close relationship between HE treatment, angiogenic processes, and overexpression of FN, but not of type IV collagen in CAM extracellular matrix. They agree with other studies proving a facilitating role of FN in angiogenic processes.

Allantois↗
PubMed1997

Endocytosis of horseradish peroxidase by brain microvascular and umbilical vein endothelial cells in culture: an ultrastructural and morphometric study.

The ability to form tight junctions and the paucity of fluid phase endocytosis showed by brain microvacular endothelial cells (BMECs) make up the structural basis of the blood-brain barrier (BBB). Most studies on cultured BMECs focused on intercellular junctions, whereas endocytosis received lesser attention. We studied endocytosis of horseradish peroxidase in primary and passage 1 and 2 BMEC cultures from rat brain as well as in human umbilical vein endothelial cell (HUVEC) culture. Endocytic activity was also analyzed in passage 1 BMECs treated with lipopolysaccharide (LPS, 1 microg/ml for 4 h), which mimics BBB disruption in bacterial meningoencephalitis. The percent of cytoplasmic area occupied by endocytic profiles (vesicles <70 nm and vacuoles >70 nm) and their mean number per cell were significantly lower in primary and passaged BMEC than in HUVEC cultures. The area and number of endocytic profiles significantly increased in BMECs after exposure to LPS. BMECs cultured under standard conditions may be a suitable model for studying the mechanism of increased fluid phase endocytosis in certain diseases and injury states.

Animals↗
PubMed1997

An immunohistochemical and morphometric study on astrocytes and microvasculature in the human cerebral cortex.

In this study, astrocytes and microvessels of the human cerebral cortex were analysed morphometrically with the aim of acquiring quantitative information on the glio-vascular relationships, considered to be of great importance in the formation and functioning of the blood-brain barrier. Immunohistochemistry for the astrocytic marker, glial fibrillary acidic protein, was used with a computerized image analysis system. The brain tissue was embedded using the progressive lowering of temperature method, and the image analyser was applied to semithin sections subjected to immunogold-silver staining and viewed by epipolarization microscopy. The results show that, in the human cerebral cortex, astrocytes cover 11.4% of the cortex area and that their perivascular processes are nearly as extensive as the vascular bed (0.8% versus 1.72% of the cortex area). These processes form a virtually continuous sheath around the vascular walls, only 11% of the vessel perimeter lacking this astrocytic glia covering. The present results, compared with previous unpublished data obtained by conventional immunocytochemical procedures on wax sections, indicate that low-temperature methods combined with gold-silver immunolabelling on semithin sections significantly improve the detection of immunoreactivity and the performance of the image analyser.

Astrocytes↗
PubMed1997

Glucose transporter GLUT1 in human brain microvessels revealed by ultrastructural immunocytochemistry.

The brain glucose transporter GLUT1 is a transmembrane glycoprotein belonging to the glucose carrier family comprising five isoforms characterized by different functional properties and tissue specificity. Biochemical and immunohistochemical analyses have demonstrated that GLUT isoform 1 is localised within the brain microvascular endothelium, where it controls glucose uptake through the blood-brain barrier (BBB). In this study the expression of GLUT1 was analysed by means of light and electron immunocytochemistry in the adult human cerebellar cortex. The glucose transporter is strongly expressed in cerebellum microvessels, and is localised not only within endothelial cells but also in microvascular pericytes. Moreover, some glial expression of GLUT1 was observed in the neutrophil and in perivascular glial sheaths. The observations demonstrate that different cellular types are involved in the control of brain glucose homeostasis by GLUT1 expression at the BBB site, and support the postulated highly specialised role of brain microvascular pericytes.

Adult↗
PubMed1996

Vasoactive intestinal polypeptide-like immunoreactivity in astrocytes of the human brain.

Vasoactive intestinal polypeptide-like immunoreactive (VIP-LIR) astrocytes were found in the subcortical white matter of the human forebrain parietal lobe. Astrocytes expressing VIP-LIR represented a minority (0.97%) of the GFAP-stained astrocyte population in the white matter. The close anatomical relationship between the VIP-LIR astrocyte bodies and processes and the brain vasculature strongly suggests that they may play a role in the local control of blood flow and of the barrier properties of the vessel walls.

Astrocytes↗
PubMed1996

Morphological aspects of the vascularization in intraventricular neural transplants from embryo to embryo.

Intraventricular transplants of neural tissues were performed in ovo from embryo to embryo. Fragments of the nervous wall of the optic lobe (tectum) from 14-day chick or 12-day quail embryos (donor) were inserted into the ventricle of the right optic lobe of 6-day chick or 5-day quail embryos (host). Chick-to-chick, chick-to-quail and quail-to-chick grafts were carried out. The vascularization changes occurring in the host tectum and in the grafted neural tissues were analysed under light, transmission, and scanning electron microscopes and by morphometric methods. In the host embryo tectum, the neural graft stimulates a statistically significant increment in vessel density and a vessel sprouting into the ventricle of the optic lobe. The vascular sprouts reach the transplanted tissue and establish connections with its native microvasculature. The chick-to-quail and quail-to-chick grafts, submitted to immunoreaction with a quail-specific antibody which recognizes an antigen (MB1) present on endothelial cells, indicate that re-establishment of the circulation in the graft depends upon anastomoses between host and donor vasculatures and the rapid new growth of host-derived and donor-native vessels. The presence of macrophage-like cells escorting the new-growing vessels suggests that these cells are involved in the host and donor tissue angiogenesis.

Animals↗
PubMed1996

Urothelium damage as the primary cause of ureteropelvic junction obstruction: a new hypothesis.

Ten infants under 6 months old underwent surgery for obstruction of the ureteropelvic junction. Craniocaudal light microscopy showed subdivision of the resected ureteropelvic junction into three portions: prestenotic, stenotic, and poststenotic. The prestenotic portion was characterized by dilatation of the ureteral lumen, flattening of its mucosal folds and thinning of the urothelium; the stenotic tract showed partial or total loss of the epithelium and fibrosis of the mucosal and fibromuscular coats. No modifications were detected in the poststenotic portion. We advance the hypothesis that a primary epithelial break might cause urine to spread inside the ureteral wall and consequently the mastocytes to migrate and degranulate within the mucosal and fibromuscular coats. The histamine and prostaglandins produced by the mastocytes could induce prolonged muscular spasm, in turn responsible for increasing the intrapelvic pressure and so causing enlargement of the epithelial break. A connective tissue reaction of the ureteral wall would thus occur, which should be considered a secondary event leading to fibrotic stenosis of the ureteropelvic junction.

Child, Preschool↗
PubMed1996

The chick embryo chorioallantoic membrane as an in vivo wound healing model.

The chick embryo chorioallantoic membrane (CAM) was used as an in vivo wound healing model. A full excision of a 1 mm2 CAM area was filled by a granulation tissue after 96-120 h, which eventually formed a scar in 75% of the cases. In the remaining 25%, a solution of continuity was left which, however, was smaller in size than the one observed immediately after the excision. Under the microscope, the CAM area involved in the repair process showed: i. hyperplasia of the chorionic epithelium; ii. about three times as many microvessels and fibroblasts in the mesenchyme as in the normal adjacent control regions; iii. an inflammatory infiltrate mostly consisting of macrophages; and iv. a strong positivity for fibronectin in the extracellular matrix. The validity of this experimental model appears to be confirmed by the fact that we were able to reproduce all the critical events controlling the wound healing process, such as re-epithelization, angiogenesis, formation of an inflammatory infiltrate and deposition of one of the main constituents of the extracellular matrix, such as fibronectin.

Allantois↗
PubMed1996

VIP-like immunoreactivity within neurons and perivascular neuronal processes of the human cerebral cortex.

Using indirect immunocytochemical techniques, neurons with VIP (Vasoactive Intestinal Polypeptide)-like immunoreactivity (ir) have been demonstrated in the human cerebral cortex of the parietal lobe. In all the cortical layers containing positive neurons, perivascular immunoreactive neuronal processes have been detected: in arterioles, they are located in the adventitial and smooth muscle layers; in capillaries, they establish tight anatomical relations with the endothelium-pericyte layer and the perivascular glial sheath. Bodies of positive neurons have also been seen adhering to capillary walls. The detection of perivascular VIP-like ir provides morphological evidence of the role played by this polypeptide in the regulation of the cerebral blood flow. Moreover, the relationships between immunoreactive neuronal processes and perivascular glia might corroborate the suggestion that VIP is involved in the functioning of the blood-brain barrier.

Antibodies, Monoclonal↗
PubMed1996

The chick embryo chorioallantoic membrane as a model for in vivo research on angiogenesis.

The chick embryo chorioallantoic membrane (CAM) is an extraembryonic membrane that is commonly used in vivo to study both new vessel formation and its inhibition in response to tissues, cells, or soluble factors. Quantitative or semiquantitative methods may be used to evaluate the amount of angiogenesis and anti-angiogenesis. Thanks to the CAM system, angiogenesis could be investigated in association with normal, inflammatory and tumor tissues, and soluble factors inducing angiogenic or anti-angiogenic effects could be identified. Rabbit cornea provides an alternative in vivo system, but CAM appears to be easier to handle and less expensive. Moreover, CAM can be used with very few limitations.

Allantois↗
PubMed1995

Endogenous basic fibroblast growth factor is implicated in the vascularization of the chick embryo chorioallantoic membrane.

Chorioallantoic membrane (CAM) and chorioallantoic fluid (CAF) of the chick embryo were studied for the presence of immunoreactive and biologically active basic fibroblast growth factor (bFGF) from Day 6 to Day 18 of incubation. An immunoreactive M(r) 16,000 bFGF-like molecule was detected both in CAM and in CAF. This molecule was identified as bFGF on the basis of its molecular weight, its affinity for heparin, and its capacity to induce plasminogen activator production in cultured endothelial GM 7373 cells. The levels of biologically active and immunoreactive bFGF vary in CAM and CAF during embryonic development, maximal concentrations being observed between Days 10 and 14 of incubation. At all time points investigated, absolute concentrations of bFGF were significantly higher in CAM (ranging from 25 to 183 ng/g of wet tissue) than in CAF (ranging from 0.2 to 4 ng/ml). In a parallel series of experiments performed at Day 8 and evaluated at Day 12 of chick embryo development, human recombinant bFGF and neutralizing anti-bFGF antibody were investigated for their capacity to affect the vasoproliferative processes of the CAM. The two molecules either were applied onto the surface of the CAM or were injected into the allantoic sac. When bFGF or anti-bFGF antibodies were absorbed on methylcellulose discs and applied on the top of the CAM, they exerted a strong angiogenic or anti-angiogenic effect, respectively. On the contrary, when bFGF or the corresponding neutralizing antibody was injected into the allantoic sac, no modifications of the vasoproliferative processes of the CAM were observed at either the macroscopic or the microscopic level. These results provide evidence indicating that endogenous bFGF has a rate-limiting role in the vascularization of the CAM during chick embryogenesis. bFGF located within the CAM, rather than that present in the CAF, appears to be involved in this developmental process.

Allantois↗
PubMed1995

Angiogenesis in pre-eclampsia.

OBJECTIVE: To study the angiogenetic activity of decidua basalis from primigravid women with pre-eclampsia. STUDY DESIGN: Fresh fragments of decidua basalis from 10 primigravid women with pre-eclampsia and from 10 healthy, control primigravid women, were grafted onto the chick embryo chorioallantoic membrane (CAM) at the 6th incubation day. Four days later the CAMs were fixed and the angiogenic response of the CAMs was assessed on histologic sections by a planimetric point-count method. RESULTS: Decidua from pre-eclamptic pregnancies induced angiogenesis to a greater extent than that from normotensive pregnancies. CONCLUSIONS: Angiogenesis might be stimulated in pre-eclampsia through endothelia and decidua changes induced by the pathological condition which, in turn, would lead to a greater expression of angiogenic factors also present in normal condition.

Allantois↗
PubMed1995

Left ventricular hypertrophy in spontaneously hypertensive rat: effects of ACE-inhibition on myocardiocyte ultrastructure.

The aim of this study is to investigate the effects of two ACE-inhibitors with different chemical formulae, cilazapril (CLZ) and captopril (CPT), on left ventricular myocardiocytes from spontaneously hypertensive rats (SHR), characterized by ultrastructural alterations associated with left ventricular hypertrophy, and from Wistar-Kyoto (WKY) rats, considered as controls. After CLZ-treatment, not remarkable changes are observed in WKY myocardiocytes, whereas SHR ones show a considerable reduction in their original alterations in ultrastructure. After CPT-treatment, both SHR and WKY myocardiocytes are altered in ultrastructure. The morphometric investigation confirms that CPT and CLZ produce different effects. Even if the drugs induce a similar decrease in blood pressure and left ventricular mass index, CLZ unlike CPT seems to improve the ultrastructural abnormalities associated with left ventricular hypertrophy. These changes could be related to the different chemical structure of CLZ and CPT, or to a different affinity of the two drugs for the local renin-angiotensin system.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1995

Angiogenesis in B cell lymphoproliferative diseases. Biological and clinical studies.

Angiogenesis is a necessary step in solid tumor progression (growth, invasion and metastasis) with which it correlates and is indicative of an unfavourable prognosis. We observed bone marrow angiogenesis in patients with active multiple myeloma (MM), though not in patients with non-active MM nor with monoclonal gammopathies of undetermined significance (MGUS). Microvessel density increased in parallel with the labeling index (LI%)--an indicator of plasma cell proliferating activity that correlates with prognosis--and defined a risk of MM progression in much the same way as LI% itself. Consequently, bone marrow angiogenesis could be an indication for unfavourable prognosis in MGUS and MM. Angiogenesis has also been demonstrated in lymph nodes involved by B cell non Hodgkin's lymphoma (B-NHL) belonging to the Working Formulation intermediate-grade (diffuse subtypes), and high-grade categories, but not in the low-grade and intermediate-grade (follicular subtype) categories. It correlated with the B-NHL cell proliferating activity, since large increments in this activity have already been demonstrated in intermediate- and high-grade vs low-grade tumors. Active MM, intermediate-grade, diffuse subtypes, and high-grade B-NHLs correspond to the vascular phases of B cell lymphoproliferative diseases, and could thus be assimilated to locally invasive and metastatic solid tumors. Similarly to solid tumors during these stages of progression, tumor B cells are also capable of inducing angiogenesis, both directly and indirectly by activating the inflammation infiltrate--a possibility that was first demonstrated by means of B-NHL implants onto the chick embryo chorioallantoic membrane. Anti-angiogenic therapy can be envisaged as a possible future development.

Bone Marrow↗
PubMed1995

Glial cells and blood-brain barrier in the human cerebral cortex.

The spatial relationship established between glial cells and microvasculature in the human cerebral cortex was analysed on peritumoral tissue of the parietal lobe removed during surgery. Observations performed by light microscope immunocytochemistry demonstrated that processes of astrocytes, strongly immunoreactive to both glial fibrillary acidic protein and S-100 protein, form sheaths to the capillaries, and that isolated cells positive to the oligodendrocyte marker 2',3'-cyclic nucleotide 3'-phosphodiesterase are detectable in perivascular areas. Morphometrical analysis by transmission electron microscopy showed that 80% of the vascular endothelium-pericyte layer is invested by small endfeet of astrocyte processes. This study demonstrates that either astrocyte bodies or oligodendrocytes as well as microgliocytes may substitute the astrocytic endfeet adhering to the capillary basement lamina.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1995

A compared TEM/SEM investigation on the pericytic investment in developing microvasculature of the chick optic tectum.

The pericytes have been ultrastructurally and morphometrically analyzed in the neural vessels of the chick embryo optic tectum, under the transmission and scanning electron microscopes. The observations demonstrated that shape and surface features of pericytes, as well as their spatial relation with the endothelium, remarkably change during development, whereas their ultrastructure does not substantially modify from the early to the late embryonic stages. The pericytes have an ovoid body, broad processes, smooth surfaces, and are closely applied to the endothelial tube on days 5-7; they show convolute shape, highly irregular surfaces, and are complicately interdigitated with the endothelial cells, when a vivacious vessel growth takes place, on days 12-14; finally, they are flattened, smooth, highly branched, and completely enclosed in the basement lamina on days 20-21, when a definitive vascular pattern is established. The contribution of pericytes to the formation of the basement lamina has been confirmed by the detection of exocytotic vesicles discharging their content toward the subendothelial cleft. The morphometric evaluations revealed that pericytes provide the growing neural microvessels with an almost continuous coverage which, however, undergoes a significant reduction within hatching time. On the whole, the results suggest that the pericytes are as active as the endothelial cells during the vessel growth and play an inhibitory role on the endothelial proliferation only later on, when they are closely adherent to the endothelium and are encompassed by the basement lamina.

Animals↗