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L Petrelli

Publications and source records attributed to L Petrelli.

At least 19 recordsLinked to original sources
PubMed2007

Ultrastructural characterization of calcification onset and progression in subdermally implanted aortic valves. Histochemical and spectrometric data.

Detailed characterization of the subdermal model is a significant tool for better understanding of calcification mechanisms occurring in heart valves. In previous ultrastructural investigation on six-week-implantated aortic valve leaflets, modified pre-embedding glutaraldehyde-cuprolinic-blue reactions (GA-CB) enabled sample decalcification with concurrent retention/staining of lipid-containing polyanionic material, which lined cells and cell-derived matrix-vesicle-like bodies (phthalocyanin-positive layers: PPLs) co-localizing with the earliest apatite nucleation sites. Additional post-embedding silver staining (GA-CB-S) revealed PPLs to contain calcium-binding sites. This investigation concerns valve leaflets subjected to shorter implantation times to shed light on the modifications associated with PPLs generation and calcification onset/progression. Spectrometric estimations revealed time-dependent calcium increase, for unreacted samples, and copper modifications indicating an increase in acidic, non-glycanic material, for GA-CB-reacted samples. Two-day-implant thin sections showed emission and subsequent reabsorption of lamellipodium-like protrusions by cells, originating ECM-containing vacuoles, and/or degeneration stages characterized by the appearance of GA-CB-S-reactive, organule-derived dense bodies and progressive dissolution of all cell membranes. In one-week-implants, the first PPL-lined cells were found to co-exist with cells where GA-CB-S-reactive material accumulated, or exudated towards their edges, or outcropped at the ECM milieu, so acquiring PPL features. PPL-derived material was observed increasingly to affect the ECM on thin sections of one-week- to six-week-implants. These results show an endogenous source for PPLs and reveal that a peculiar cascade of cell degenerative steps is associated with valve mineralization in the subdermal model, providing new useful parameters for more reliable comparison of this experimental calcification process versus the physiological and pathological processes.

Animals↗
PubMed2003

Isolation of intact aortic valve scaffolds for heart-valve bioprostheses: extracellular matrix structure, prevention from calcification, and cell repopulation features.

Extracellular matrix (ECM) scaffolds isolated from valvulated conduits can be useful in developing durable bioprostheses by tissue engineering provided that anatomical shape, architecture, and mechanical properties are preserved. As evidenced by SEM, intact scaffolds were derived from porcine aortic valves by the combined use of Triton X-100 and cholate (TRI-COL) or N-cetylpyridinium (CPC) and subsequent nucleic acid removal by nuclease. Both treatments were effective in removing most cells and all the cytomembranes, with preservation of (1) endothelium basal membranes, (2) ECM texture, including the D-periodical interaction of small proteoglycans with normally D-banded collagen fibrils, and (3) mechanical properties of the treated valves. Ultrastructural features agreed with DNA, hexosamine, and uronic acid biochemical estimations. Calcification potential, assessed by a 6-week rat subdermal model, was significantly reduced by TRI-COL/nuclease treatment. This was not true for CPC only, despite better proteoglycan preservation, suggesting that nucleic acids also are involved in calcification onset. Human fibroblasts, used to repopulate TRI-COL samples, formed mono- or multilayers on surfaces, and groups of cells also were scattered within the valve leaflet framework. A biocompatible scaffolds of this kind holds promise for production of durable valve bioprostheses that will be able to undergo probable turnover and/or remodeling by repopulating recipient cells.

Animals↗
PubMed2003

Malachite green and phthalocyanine-silver reactions reveal acidic phospholipid involvement in calcification of porcine aortic valves in rat subdermal model.

Subdermal implant models are helpful in the study of calcification "in vivo" and for testing anticalcific treatments. After implantation of porcine aortic valve leaflets in rat subcutis, we previously found that glutaraldehyde-Cuprolinic blue reactions (GA-CB) at low pH induce favourable tissue unmasking from mineral deposits, and visualize peculiar, electrondense layers that outline the calcifying cells and matrix vesicle-like structures. The layer-forming material seemed to consist of acidic phospholipids because of its anionic nature and differential susceptibility to chemical/enzymatic extractivity. In the present investigation, pre-embedding glutaraldehyde-Malachite green (GA-MG) reactions and subsequent osmium post-fixation were compared with pre-embedding GA-CB reactions, combined with post-embedding von Kossa silver staining (GA-CB-S), to assess whether the layer-forming material is actually composed of acidic phospholipids and exhibits calcium-binding properties. After lowering standard pH, GA-MG reactions also caused sample demineralization and the appearance of pericellular osmium-MG-reactive layers comparable to CB-reactive ones. Moreover, GA-CB-S reactions showed that major silver precipitation was superimposed to the CB-reactive layers, whereas minor metal extra-precipitation occurred at three distinct, additional sites. These results demonstrate that a unique process of cell degeneration occurs in this calcification model, in which acidic phospholipids accumulate at cell surface, replacing cell membrane and acting as major apatite nucleator. However, the overall observations are consistent with the hypothesis that certain phases are common to the various types of normal and/or abnormal calcification.

Animals↗
PubMed2002

Novel ultrastructural features as revealed by phthalocyanine reactions indicate cell priming for calcification in subdermally implanted aortic valves.

The roles played by various determinants in physiological, pathological or experimental calcification are still unclear. In this investigation, new insights were gained into structural changes occurring in porcine aortic valves undergoing mineralization in the rat subdermal model and then subjected to reactions with cationic phthalocyanines (PHTs), at salt-critical electrolyte concentrations (CEC). PHT reactions showed decalcifying effects, depending on both acidic pH in the media employed and mineral substitution by Cuprolinic Blue (CB) itself, as well as specific reactivity which enabled the ultrastructural detection of unusual, PHT-positive layers (PPLs) encircling cells and matrix vesicles, at 0.05 M CEC conditions. Other reactions at different CEC conditions, or subsequent to enzymatical or specific extractive treatments, suggest PPL appearance is due to PHT uptake by clustered anionic phospholipids, which seem to be involved in mineral precipitation. PPLs present as a novel, reliable ultrastructural parameter indicating cell propensity in priming experimental and, possibly, pathological calcification.

Animals↗
PubMed2001

[Experimental model of infection of Helicobacter pylori in the mouse. A study of gastric damage caused by indomethacin].

INTRODUCTION: The action of non-steroidal anti-inflammatory drugs (NSAIDs) on the Helicobacter Pylori (Hp) infected mucosa is a matter of debate. Some authors consider them to cause additive iatrogeny whilst others attribute a purportedly protective action to them. The development of on experimental animal model could help clarify this phenomenon. OBJECTIVES: 1--To develop an animal model of Hp gastric infection. 2--To evaluate the aggressiveness of NSAIDs in this model. MATERIALS AND METHODS: Male 6 month old BALC/C mice weighing 38 g were studied. Pylori Hp infection was ruled out. On three occasions, in the same week, 18 mice were inoculated intra-gastrically with 0.6 ml of Hp culture broth (brain-heart infusion) containing 1 x 10 8-1 x 10 9 CFU/ml. Another group of mice were inoculated with sterile saline. After two months the mice were killed and their stomachs studied. They were divided into groups: a) 6 Hp negative control mice. b) 8 Hp negative mice with prior intra-peritoneal injection of 25 mg/Kg indomethacin (24 hs.) c) 8 mice inoculated with Hp with indomethacin. d) 8 mice inoculated with Hp, without indomethacin. The stomachs were opened along the greater curvature and photographed macroscopically in order to map the necrotic area. The antrums were biopsied to test for urease and separate antrum and body specimens were send for staining with Warthin-Starry H & B and histopathology. RESULTS: All the mice inoculated with Hp acquired the infection. The necrotic area was larger in Group B: 55.5 +/- 7.87 mm than in Group C: 15 +/- 1.82 mm P < 0.00019. HISTOLOGY: Group A: normal mucosa. Group B: extensive coagulation necrosis and focal erosions. Group C: ulcers with inflammatory infiltrate and smaller necrotic area, presence of Hp on the surface epithelium. Group D: no ulcers, Hp present. CONCLUSION: An animal model of Hp infection was successfully developed Hp infection could play a potentially protective role against indomethacin aggression in the mouse.

Animals↗
PubMed1999

Human immunodeficiency virus type 1 envelope glycoprotein gp120 induces tumor necrosis factor-alpha in astrocytes.

gp120 induction of the inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) was studied in cultures of purified astrocytes. Incubation of pure mouse cortical astrocytes with gp120 IIIB induced the expression of TNF-alpha mRNA, assessed by in situ hybridization. Anti- TNF-alpha immunocytochemical staining of gp120 IIIB stimulated astrocytes indicated the presence of TNF-alpha. gp120 IIIB treatment also stimulated secretion of bioactive TNF-alpha from astrocytes, which was prevented by inhibitors of transcription and translation. Hippocampal and cerebellar astrocytes displayed similar behaviors. Further, gp120 displayed cytotoxicity for astrocytes that depended on macromolecular synthesis. The data are the first to show gp120 IIIB induction of de novo TNF-alpha production by pure astrocytes. Because TNF-alpha exerts a wide array of effects in the brain of infected individuals and has HIV-1 inducing activity as well, induction of this cytokine by gp120 IIIB in astrocytes may contribute importantly to the pathogenesis of AIDS dementia complex. Since TNF-alpha can stimulate astrocyte reactivity and proliferation by an autocrine mechanism, the extent of the gp120 effect could conceivably increase with HIV-1 disease progression in a self-amplifying loop, involving other cell types, thus favoring both virus persistence and a chronic disease state.

Animals↗
PubMed1997

Salt: a sacred substance.

Salt is the last relic of the ocean where life was born. Its presence has influenced the whole gamut of history and its name is linked to hundred of geographical locations. Its importance for nutrition is supported by the discovery of Aeneolithic salt cellars. Salt cellars and pyramids of salt have been included in paintings and other works of art. In Japan where salt was and still is obtained from the sea, a salt culture has developed that can be traced in the rituals of everyday life, including meal preparation, sports, and Shinto ceremonies.

Art↗
PubMed1996

The ALIAmide palmitoylethanolamide and cannabinoids, but not anandamide, are protective in a delayed postglutamate paradigm of excitotoxic death in cerebellar granule neurons.

The amino acid L-glutamate is a neurotransmitter that mediates fast neuronal excitation in a majority of synapses in the central nervous system. Glutamate stimulates both N-methyl-D-aspartate (NMDA) and non-NMDA receptors. While activation of NMDA receptors has been implicated in a variety of neurophysiologic processes, excessive NMDA receptor stimulation (excitotoxicity) is thought to be primarily responsible for neuronal injury in a wide variety of acute neurological disorders including hypoxia-ischemia, seizures, and trauma. Very little is known about endogenous molecules and mechanisms capable of modulating excitotoxic neuronal death. Saturated N-acylethanolamides like palmitoylethanolamide accumulate in ischemic tissues and are synthesized by neurons upon excitatory amino acid receptor activation. Here we report that palmitoylethanolamide, but not the cognate N-acylamide anandamide (the ethanolamide of arachidonic acid), protects cultured mouse cerebellar granule cells against glutamate toxicity in a delayed postagonist paradigm. Palmitoylethanolamide reduced this injury in a concentration-dependent manner and was maximally effective when added 15-min postglutamate. Cannabinoids, which like palmitoylethanolamide are functionally active at the peripheral cannabinoid receptor CB2 on mast cells, also prevented neuron loss in this delayed postglutamate model. Furthermore, the neuroprotective effects of palmitoylethanolamide, as well as that of the active cannabinoids, were efficiently antagonized by the candidate central cannabinoid receptor (CB1) agonist anandamide. Analogous pharmacological behaviors have been observed for palmitoylethanolamide (ALI-Amides) in downmodulating mast cell activation. Cerebellar granule cells expressed mRNA for CB1 and CB2 by in situ hybridization, while two cannabinoid binding sites were detected in cerebellar membranes. The results suggest that (i) non-CB1 cannabinoid receptors control, upon agonist binding, the downstream consequences of an excitotoxic stimulus; (ii) palmitoylethanolamide, unlike anandamide, behaves as an endogenous agonist for CB2-like receptors on granule cells; and (iii) activation of such receptors may serve to downmodulate deleterious cellular processes following pathological events or noxious stimuli in both the nervous and immune systems.

Amides↗
PubMed1996

N-(2-hydroxyethyl)hexadecanamide is orally active in reducing edema formation and inflammatory hyperalgesia by down-modulating mast cell activation.

Mast cells play a key role in inflammatory reactions triggered by tissue injury or immune perturbations. Little is known about endogenous molecules and mechanisms capable of modulating inappropriate mast cell activity. N-(2-Hydroxyethyl)hexadecanamide (palmitoylethanolamide), found in peripheral tissues, has been proposed to act as a local autacoid capable of negatively regulating mast cell activation and inflammation-hence the acronym Autacoid Local Inflammation Antagonism (ALIA). Recently, N-(2-hydroxyethyl)hexadecanamide (LG 2110/1) has been reported to down-modulate mast cell activation in vitro by behaving as an agonist at the peripheral cannabinoid CB2 receptor. Here, we have characterized and functionally correlated the anti-inflammatory actions of LG 2110/1 with its ability to control mast cell activation, when given orally in a battery of rodent models of inflammation. LG 2110/1 diminished, in a dose-dependent and correllated manner, the number of degranulated mast cells and plasma extravasation induced by substance P injection in the mouse ear pinna. In addition, LG 2110/1 reduced dose dependently plasma extravasation induced by passive cutaneous anaphylaxis reaction. In adult rats LG 2110/1 decreased, in a dose-dependent manner, carrageenan-induced hindpaw edema and hyperalgesia, but not phospholipase A2-induced hindpaw edema. Further, anti-edema effects were observed when utilizing dextran and formalin, known to also cause mast cell activation. Locally administered LG 2110/1 was likewise effective in minimizing dextran-induced hind paw edema. In contrast, equivalent amounts of palmitic acid plus ethanolamine were ineffective against plasma extravasation provoked by substance P. LG 2110/1 did not decrease plasma extravasation induced by the substance P fragment, substance P-(6-11), known to be inactive on mast cells. These results indicate that orally administered N-(2-hydroxyethyl)hexadecanamide is effective in: (a) directly down-modulating mast cell activation in vivo; (b) suppressing pathological consequences initiated by mast cell activation independently of the activating stimuli; (c) exerting an anti-inflammatory action distinguishable from that of classical steroidal and non-steroidal anti-inflammatory agents. These findings raise the possibility that N-(2-hydroxyethyl)hexadecanamide and related saturated N-acylamides ('ALIAmides') represent novel therapeutic agents useful in the management of inflammatory disease conditions.

Amides↗
PubMed1996

Nerve growth factor: from neurotrophin to neurokine.

Nerve growth factor (NGF) is largely known as a target-derived factor responsible for the survival and maintenance of the phenotype of specific subsets of peripheral neurones and basal forebrain cholinergic nuclei during development and maturation. However, NGF also exerts a modulatory role on sensory, nociceptive nerve physiology during adulthood that appears to correlate with hyperalgesic phenomena occurring in tissue inflammation. Other NGF-responsive cells are now recognized as belonging to the haemopoietic-immune system and to populations in the brain involved in neuroendocrine functions. The concentration of NGF is elevated in a number of inflammatory and autoimmune states in conjunction with an increased accumulation of mast cells. Mast cells and NGF appear to be involved in neuroimmune interactions and tissue inflammation, with NGF acting as a general 'alert' molecule capable of recruiting and priming tissue defence processes following insult as well as systemic defensive mechanisms. Moreover, mast cells themselves produce NGF, suggesting that alterations in normal mast cell behaviours can provoke maladaptive neuroimmune tissue responses whose consequences could have profound implications in inflammatory disease states. This review discusses recent discoveries involving novel and diverse biological activities of this fascinating molecule.

Animals↗
PubMed1996

Unusual ultrastructural features in intrafascicular ganglion cells of the rat pelvic nerve.

The incidental finding of four ectopic ganglion cells within the pelvic nerve of a normal rat prompted a thorough electron microscopic investigation of the ultrastructural features of these neurons. They were found to enwrap presynaptic terminals inside crater-like invaginations; the appositional surfaces were made more complex by the presence of slender dendritic appendages and sheet-like processes of glial cells. The presynaptic elements contained both clear and dense-cored vesicles, and appeared similar to those characterizing SIF (paraneuronal) cells. In addition, cilia were encountered in both the invaginated processes and most of the Schwann cells associated with the pre- and postsynaptic nerve cells and their processes. Overall, these features were deemed worth reporting because 1) of the unusual features of synaptic input from a SIF cell to a ganglion cell associated with the pelvic plexus, and 2) the ectopic ganglion cells possibly represent the sole example, other than ciliary neurones in the avian ciliary ganglion, of postsynaptic cells encasing presynaptic endings inside their perikarya.

Animals↗
PubMed1994

Effect of cholesterol-supplemented diet in heritable hyperlipidemic Yoshida rats: functional and morphological characterization of thoracic aorta.

In this study we have considered the possibility of inducing vascular damage in Yoshida Pittsburg (YOS) rat, an inbred strain which has endogenous hyperlipidemia without vascular atherosclerotic damage. Cholesterol-enriched diet (4% cholesterol plus 1% cholic acid and 0.5% thiouracil) was administered to YOS rats, in order to induce atherogenesis. The results indicate that, despite significant increase in serum (about 2-fold) and aortic tissue cholesterol (about 6-fold), no morphological damage occurred. A reduction in acetylcholine-mediated relaxation (of about 37%) was observed. No inhibition of ATP- or sodium nitrite-induced relaxation, or of contraction induced by norepinephrine was seen. Serum triglyceride concentration did not vary after administration of a cholesterol-enriched diet. Our results suggest that in heritable hyperlipidemic Yoshida rat, after 2 months of cholesterol-enriched diet, despite increased serum cholesterol levels, no atheromatous plaque developed on the aortic wall. Impaired vascular function and reductions in the response to acetylcholine were related to changed endothelial cell function. Administration of a high cholesterol diet to YOS rat may represent a new model of mixed endogenous and exogenous hyperlipidemia that can resemble many human dislipidemic diseases and therefore may become a useful tool for the study of isolated endothelial dysfunction.

Acetylcholine↗
PubMed1994

Characterization and growth-dependent regulation of the nerve growth factor receptor gp140trk in rat C6 glioma cells.

The glioma cell line C6 was used to study the expression and growth-dependent regulation of the nerve growth factor (NGF) tyrosine kinase receptor gp140trk, which is the mature protein product of the trk proto-oncogene. Chemical cross-linking of 125I-NGF to C6 cells, followed by immunoprecipitation with polyclonal anti-NGF antibodies and separation by polyacrylamide gel electrophoresis, revealed the presence of 90-95 and 150 kDa species. Immunocytochemical staining of C6 cells with antibodies directed against either the low-affinity NGF receptor gp75NGFR or trk proto-oncogene products demonstrated a heterogeneous cellular distribution of both antigens. Brief treatment of C6 cells with NGF led to the tyrosine phosphorylation of 80, 110 and 140 kDa protein species, as detected on anti-phosphotyrosine Western blots. Similar molecular weight species were found with anti-Trk antibodies in the NGF-treated cells. Intracellular localization of Trk-like immunoreactivity in C6 cells released from a growth-arrested state indicated an initial immunostaining of the nuclear periphery, progressing to cytoplasmic vesicles and finally to the plasma membrane. These observations at the light microscopic level were confirmed using immunoelectron microscopy with the same anti-Trk antibodies, and showed clearly the trafficking of Trk-like immunostained particles from the endoplasmic reticulum to the plasmalemma. The cellular localization of trk gene products also appeared to depend on their glycosylation state. Such growth-dependent expression of NGF receptors on glial cells may be important in controlling autocrine regulatory processes of glia to NGF, which these cells produce.

Animals↗
PubMed1994

Establishment and characterization of a CHO cell line producing a secreted form of human ciliary neurotrophic factor: neuroprotective effects of the recombinant protein.

Human ciliary neurotrophic factor (CNTF) was inserted into a mammalian expression vector linked to the prepro sequence of human nerve growth factor. A Chinese hamster ovary cell line was established by resistance to neomycin and the plasmid integrated DNA was amplified using the metallothionein gene. This cell line contained several hundred copies of the human CNTF gene and produced an NH2 terminal truncated form of human CNTF (22 kDa) which was secreted into the medium. Although the copy number of the human CNTF gene was high and its mRNA was actively transcribed, the recombinant protein secreted into the medium constituted only 35-40% of the total amount of human CNTF synthesized by these cells. Both wild-type human CNTF produced in bacterial cells and the human CNTF obtained by forced secretion were effective in protecting hippocampal pyramidal neurons from injury induced by glucose deprivation, a form of excitotoxic neurodegeneration.

Amino Acid Sequence↗
PubMed1993

Neurotrophin-3 upregulates NGF receptors in a central nervous system glial cell line.

The low-affinity nerve growth factor (NGF) receptor (LNGFR) binds the neurotrophins NGF, brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) with similar affinities. Here we report on the ability of NT-3 to regulate the expression of the LNGFR in C6 glioma cells. LNGFR-like immunoreactivity (LNGFR-IR) was examined in C6 cells treated for 16 h with NT-3 and exposed to the antibody 192-IgG followed by immunoglobulins conjugated with colloidal gold by means of ultrastructural morphometric analysis. Untreated C6 cells exhibited some positive LNGFR-IR, while C6 cells treated with NT-3 displayed significantly increased (2.3 fold) LNGFR-IR. The increase in LNGFR protein was accompanied by a greater quantity of LNGFR mRNA in NT-3-treated cells. Thus, LNGFR can be upregulated by the structurally related neurotrophin NT-3.

Animals↗
PubMed1993

Ultrastructural analysis of the cavernous and dorsal penile nerves in experimental diabetes.

The present study was designed to investigate whether experimental diabetes determines structural changes in peripheral nerves involved in reflexogenic erection, namely the cavernous and the dorsal nerve of the penis. Myelinated axons were examined in the dorsal nerve of the penis from rats with streptozotocin-induced diabetes (3- and 6-month duration). Morphometric analysis disclosed a significant decrease of myelinated fibre size most likely due to a progressive axonal atrophy. In addition, morphological analysis revealed diffuse accumulation of glycogen within axons, lipid droplets in Schwann cells and pronounced sequestration of axoplasm by adaxonal Schwann cell processes. These signs were particularly prominent in 6-month-diabetic rats. Myelinated and unmyelinated axons of the cavernous nerve were analysed in 6-month-diabetic animals. No substantial ultrastructural abnormalities were found in the cavernous nerves. These results suggest that in experimental diabetes regionally specific structural changes occur in neuronal pathways subserving erectile function.

Animals↗
PubMed1993

Colocalization of low- and high-affinity NGF receptors on PC12 cells, C6 glioma cells and dorsal root ganglion neurons.

The biological responsiveness of neural cells to nerve growth factor (NGF) appears to require expression and ligand binding to both the low-affinity NGF receptor (LNGFR) and the proto-oncogene product trk, the latter being a receptor tyrosine kinase. Immunolocalization of the LNGFR and the high-affinity component of the NGF receptor, trk (HNGFR) was studied by electron microscopic morphometric analysis on cultured PC12 pheochromocytoma cells, C6 glioma cells and neonatal rat dorsal root ganglia neurons using a double immunogold labeling technique. Two receptor-specific antibodies, anti-LNGFR monoclonal antibody 192-IgG and a polyclonal antibody against the 14 carboxy-terminal amino acids of the Trk protein, were utilized in conjunction with immunoglobulin conjugated to colloidal gold particles of different sizes. All cells treated with NGF (50 ng/ml) displayed significant colocalization of LNGFR/HNGFR-like immunoreactivity. Gold particles associated with LNGFR (LNGFR-like immunoreactivity) were frequently seen near 2 or 3 (or more) particles delineating the HNGFR on all cell surfaces. Positive Trk-like immunoreactivity (HNGFR) thus seems to localize in close proximity to LNGFRs in at least these cell types.

Animals↗