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Biomedical subjects

E Lucca

Publications and source records attributed to E Lucca.

13 recordsLinked to original sources
PubMed2001

[Cor triatriatum dextrum resulting from the persistence of embryonic remnants of the right valve of the sinus venosus: prevalence and echocardiographic aspects in a large consecutive non-selected patient population].

BACKGROUND: Cor triatriatum destrum is a rare congenital malformation, usually associated with complex right heart abnormalities, characterized by a membrane that divides the right atrium into two chambers. It is considered the result of the incomplete and abnormal regression of the embryonic right valve of the sinus venosus. When the valve regresses the cephalic portion forms the crista terminalis and the caudal portion develops into the Eustachian and Thebesian valve. With an incomplete regression, a fenestrated or an unfenestrated membrane may persist in the right atrium. We describe the clinical and echocardiographic characteristics of this type of remnants in the right atrium. METHODS: In a 4-month period, 1728 transthoracic two-dimensional and Doppler echocardiographic studies were consecutively performed. RESULTS: Twenty-seven patients (16 males, 11 females, mean age 55 +/- 21 years, range 1-87 years) were occasionally recognized to be affected by a membrane inside the right atrial cavity. On the basis of its echocardiographic appearance (a membranous structure connecting the orifice of the inferior vena cava to the atrial septum with evident fenestration in 74% of cases), absence of associated congenital abnormalities (92.5% of cases), interatrial shunt or abnormal flow pattern of venous systemic return, a diagnosis of a normal benign anatomic variant of sinus venous remnants (similar to the so-called "Chiari's network") could be made in every case. CONCLUSIONS: The incomplete regression of the embryonic right valve of the sinus venosus may leave a fenestrated or an unfenestrated membrane in the right atrium that should be considered a normal benign variant of the so-called "Chiari's network".

Adolescent↗
PubMed1998

Extracellular calcium deprivation in astrocytes: regulation of mRNA expression and apoptosis.

Cell viability and gene expression were studied in primary astroglial cells cultured in a nominally calcium-free medium. Ca2+ deprivation reduced progressively the astrocytes' viability, starting from 12 h; the restoration of a normal Ca2+ concentration (1.8 mM) in the medium after 12-h deprivation reversed the degenerative effect within 24 h. Biochemical and morphological examinations indicated that cell death induced by Ca2+ deprivation was mediated by apoptosis. This was associated with the expression of c-fos, c-jun, and c-myc, which, with different time courses, were induced in astrocytes after Ca2+ deprivation. Furthermore, shifting to a Ca2+-free medium modified the expression of Ich-1S transcript and rapidly increased intracellular cyclic AMP, which has been implicated in the transcriptional activation of immediate-early genes. The absence of Ca2+ in the medium reduced the expression of constitutive proteins such as alpha-actin, clusterin, glial fibrillary acidic protein, amyloid precursor protein, and glucose-6-phosphate dehydrogenase. The expression of these mRNAs was reduced >50% after 8 h of Ca2+ deprivation, when the effect on cell viability was negligible. When Ca2+ deprivation was prolonged for 24 h the expression of mRNA dropped completely, and restoration of the Ca2+ ions in the medium for 48 h did not reverse this effect. In contrast with general assumption, the apoptotic machinery in astrocytes is activated similarly not only by increased Ca2+ influx but also with the extracellular Ca2+ deprivation.

Animals↗
PubMed1997

Influence of cell culture conditions on the protective effect of antioxidants against beta-amyloid toxicity: studies with lazaroids.

The mechanisms of cell death of rat cortical neurons chronically exposed to the beta-amyloid (betaA) biologically active fragment beta-(25-35) involve oxidative stress. We examined the influence of culture conditions on the neuroprotective activity of antioxidants against beta-(25-35) toxicity. Common radical scavengers such as N-acetylcysteine (250 microM) and N-t-butyl-phenylnitrone (500 microM) only protected cortical cells cultured in the presence of fetal calf serum (FCS) from betaA insult. The neuroprotective effect of lazaroids (U74389G and U83836E), 21-aminosteroids with antioxidant activity, was tested in cells grown with or without FCS. U74389G did not interfere with beta-(25-35) toxicity in either condition, while U83836E at a very low concentration (15 nM) protected cortical cells exposed to the beta peptide only when the neurons were cultured in the presence of FCS. These data show that a lazaroid can prevent beta-(25-35) toxicity and that the antioxidants exerted their protective effect in certain conditions.

Amyloid beta-Peptides↗
PubMed1997

Beta-amyloid fragment potentiates IL-6 and TNF-alpha secretion by LPS in astrocytes but not in microglia.

The effect of a peptide homologous to the biologically active fragment of beta amyloid 25-35 (beta 25-35) was studied on interleukin 6 (IL-6) and tumour necrosis factor (TNF-alpha) secretion induced by lipopolysaccharide (LPS) in primary rat astrocytes and microglia. Twenty-four hour exposure to LPS (50 ng/ml) induced IL-6 and TNF-alpha both in astrocytes and in microglial cells, while the effect of beta 25-35 (50 microM) per se was negligible in both cell types. In microglial cells, the application of beta peptide did not alter the production of either cytokine induced by LPS. However, beta 25-35 strongly amplified the production of both IL-6 and TNF-alpha in astrocytes. These findings confirm the complex interaction between cytokines and amyloidogenesis in Alzheimer's disease and indicate that astrocytes rather than microglia respond to the beta amyloid fragment, suggesting that these cells may be actively involved in cytokine-mediated events in AD.

Amyloid beta-Peptides↗
PubMed1997

Densitometric quantification of neuronal viability by computerized image analysis.

A new method is presented for the quantification of cell viability based on densitometry with computerized image analysis. Neuronal cells were stained with crystal violet and densitometric analysis was performed with an IBAS 2.0 image analyzer (Kontron/ Zeiss), using specially implemented dedicated software which integrates the optical density of the culture in each well with the area covered by the stained cells. To test the reliability of the densitometric method cortical cells were plated at different concentrations (5 x 10(4)-10(6)/ml); the standard curve obtained by analysis of crystal violet staining showed a linear proportion between cell number and optical density signal. The validation and accuracy of the method were assessed and compared with other methods using rat cortical cells cultured in vitro for 10 days and exposed to kainic acid (250 microM) for 24 h. Neuronal viability was reduced by 40-50% and comparison with direct cell counting, MTT assay, and spectrophotometric analysis confirmed that the method is simple, quick, and reliable.

Animals↗
PubMed1997

Neuroprotective effect of somatostatin on nonapoptotic NMDA-induced neuronal death: role of cyclic GMP.

Somatostatin (SRIF) exerts a modulatory function on neuronal transmission in the CNS. It has been proposed that a reduction of calcium currents is the major determinant of the inhibitory activity of this peptide on synaptic transmission. Because the neurotoxicity induced by activation of the NMDA subtype of glutamate receptor is mediated through excessive Ca2+ influx, we investigated whether SRIF counteracted NMDA-induced neuronal cell death. Neurons from embryonic rat cerebral cortex were cultured for 7-10 days and then exposed to 0.5 and 1 mM NMDA for 24 h. The neuronal viability, as assessed by the colorimetric method, decreased by 40 and 60%, respectively, compared with the control condition. Morphological and biochemical evidence indicated that cell death occurred by necrosis and not through an apoptotic mechanism. SRIF (0.5-10 microM), simultaneously applied with excitatory amino acid, significantly reduced in a dose-dependent manner the neurotoxic effect of NMDA but not that of KA (0.25-0.5 mM). GABA (10 microM) partially protected neurons to a similar extent from NMDA- or KA-induced toxicity. SRIF type 2 receptor agonists, octreotide (SMS 201-995; 10 microM) and vapreotide (RC 160; 10 microM), did not influence the NMDA-dependent neurotoxicity. The intracellular mechanism involved in SRIF neuroprotection was investigated. Pertussin toxin (300 ng/ml), a G protein blocker, antagonized the protective effect of SRIF on NMDA neurotoxicity. Furthermore, the neuroprotective effect of SRIF was mimicked by dibutyryl-cyclic GMP (10 microM), a cyclic GMP analogue, whereas 8-(4-chlorphenylthio)-cyclic AMP (10 microM), a cyclic AMP analogue, was ineffective. The cyclic GMP content was increased in a dose-dependent manner by SRIF (2.5-10 microM). Finally, both specific (Rp-8-bromoguanosine 3',5'-monophosphate, 10 microM) and nonspecific [1-(5 isoquinolinylsulfonyl)-2-methylpiperazine (H7), 10 microM] cyclic GMP-dependent protein kinase (cGMP-PK) inhibitors did not interfere with NMDA toxicity but substantially reduced SRIF neuroprotection. Our data suggest a selective neuroprotective role of SRIF versus NMDA-induced nonapoptotic neuronal death in cortical cells. This effect is likely mediated by cGMP-PK presumably by regulation of the intracellular Ca2+ level.

Animals↗
PubMed1997

Prion protein fragment 106-126 differentially induces heme oxygenase-1 mRNA in cultured neurons and astroglial cells.

Heme oxygenase (HO), which catalyzes the degradation of heme, has two isozymes (HO-1 and HO-2). In brain the noninducible HO-2 isoform is predominant, whereas the inducible HO-1 is a marker of oxidative stress. Because brain oxidative stress might be present in prion-related encephalopathies (PREs), as in other neurodegenerative diseases, we investigated whether HO-1 mRNA was induced in neuronal and astroglial cell cultures by a peptide corresponding to residue 106-126 of human prion protein (PrP). This peptide is amyloidogenic, and when added in vitro to cultured cells it reproduces the neuronal death and astroglial proliferation and hypertrophy occurring in PREs. HO-1 mRNA did not accumulate in rat cultured neurons from hippocampus or cortex exposed to PrP 106-126 (50 microM for 5 days). PrP 106-126 induced HO-1 mRNA accumulation in rat astroglial cultures depending on the exposure time and concentration, being maximal (33-fold) after 7 days of exposure at 50 microM. The nonamyloidogenic amidated or amidated-acetylated PrP 106-126 was ineffective, as was a scrambled peptide used as control. N-Acetylcysteine reduced (50%) the accumulation of HO-1 mRNA in astroglial cells after PrP 106-126 (25 microM) given for 5 days. Thus, oxidative stress is apparently a feature of the toxicity of PrP 106-126, and it might also occur in PREs; induction of HO-1 could contribute to the greater resistance of astrocytes compared with neurons to PrP 106-126 toxicity.

Acetylcysteine↗
PubMed1997

Amidation of beta-amyloid peptide strongly reduced the amyloidogenic activity without alteration of the neurotoxicity.

Beta-amyloid accumulates in cerebral deposits in Alzheimer's disease, so to test the correlation between the neurotoxic and fibrillogenic capacity of beta-amyloid, we synthesized a peptide homologous to fragment 25-35 of beta-amyloid (beta25-35) and amidated at the C-terminus (beta25-35-NH2). As the amidation strongly reduced the amyloidogenic capacity of beta25-35, we compared its neurotoxic activity in the amidated (beta25-35-NH2) and nonamidated forms. The viability of primary cultures from fetal rat hippocampus was reduced in a dose-related manner (10-100 microM) similarly by beta25-35 and beta25-35-NH2, whereas a scrambled peptide, amidated or nonamidated, did not alter the neuronal viability. The neurotoxic activity of beta25-35-NH2 is mediated by apoptosis as demonstrated by morphological and biochemical investigations. Electron microscopy examination of culture media with beta25-35 or beta25-35-NH2 incubated with neuronal cells for 7 days confirmed the high level of fibrillogenic activity of beta25-35 and the almost total absence of fibrils in the solution with beta25-35-NH2. Furthermore, staining with thioflavine S was used to identify amyloid fibrils, and only the cultures exposed to beta25-35 exhibited intense staining associated with neuronal membranes. These data indicate that the neurotoxic activity of the beta-amyloid fragment is independent of the aggregated state of the peptide.

Amino Acid Sequence↗
PubMed1996

Oxidative stress after acute and chronic application of beta-amyloid fragment 25-35 in cortical cultures.

The aim of this work was to investigate whether free radical reactions play a role in beta-amyloid neurotoxicity. Rat cortical neurons were exposed acutely (24 h) or chronically (3, 7 days) to beta-amyloid biologically active fragment beta 25-35 (50 microM). In these conditions, where only the longest exposure induced neuronal death, superoxide dismutase activity was increased after acute exposure but no change was detected after chronic treatments, whereas a different pattern was observed for glutathione peroxidase. In the basal condition, there was an eight-fold increase in dichlorofluoroscein, used as peroxide production marker, in neuronal cells after 7 days treatment with beta 25-35. Moreover, the intracellular peroxide production induced by Fe2+/ascorbate stimulation was amplified by beta 25-35, increasingly up to 7 days of exposure, by which time the dichlorofluoroscein-stimulated levels were 33 times higher than in controls. In conclusion, our results show that oxidative stress and free radical production are linked to beta 25-35 exposure and may contribute to neurodegenerative events associated with beta-amyloid deposits in Alzheimer's disease.

Alzheimer Disease↗
PubMed1996

Clusterin (SGP-2) induction in rat astroglial cells exposed to prion protein fragment 106-126.

Prion-related encephalopathies are characterized by the accumulation of an abnormal prion protein isoform (PrPSc) associated with neuronal degeneration and astrogliosis. The synthetic peptide homologous to PrP fragment 106-126 (PrP 106-126) induced in vitro neuronal apoptosis and glial proliferation. We used Northern blot analysis and the RNA polymerase chain reaction to assess the expression of several genes associated with programmed cell death and proliferation. Blots of total RNA extracted from neuronal and astroglial cells exposed to PrP 106-126 for between 1 h and 7 days were hybridized with probes recognizing c-fos, c-jun, c-myc, p53, hsp-70 and bcl-2 mRNA. Except for a slight decrease in bcl-2 mRNA in neuronal cells, no change in other transcripts was evident. Since clusterin (apolipoprotein J) mRNA levels are increased in prion-related encephalopathies and clusterin immunoreactivity has been located in association with PrPSc in Gerstmann-Sträussler-Scheinker brain, the expression of clusterin was determined in neuronal and astroglial cells chronically exposed to PrP 106-126. Although the induction of clusterin has been involved in the apoptotic mechanism in other experimental conditions, its expression was unchanged in PrP 106-126-treated neurons, while a three-fold induction of clusterin mRNA was observed in astrocytes exposed to PrP 106-126. To investigate whether the clusterin up-regulation was simply associated with the astroglial proliferative stimulus of PrP 106-126 or was specifically induced by the peptide, we measured clusterin expression in astrocytes cultured in fetal calf serum-free medium and exposed to PrP 106-126 or fetal calf serum restoration. In this condition the PrP peptide, like fetal calf serum, increased the glial proliferation rate, but only PrP 106-126 doubled clusterin mRNA. The selectivity of this effect indicates that PrPSc is directly involved in the clusterin up-regulation seen in prion-related encephalopathies and is associated with astroglial cells.

Animals↗
PubMed1996

[Solid papillary tumor of the pancreas. A clinical case].

The solid papillary tumor of the pancreas is a relative rare neoplasm that often is unknown because of its diagnostic difficulties. It is frequent in young women. It has no typical clinical signs, sometimes produces abdominal mass, sometimes is found casually during investigations for other diseases. Instead the prognosis of this tumor is more typical: long-term survival is good. The natural history of the solid papillary is the same as neoplasm with a low malignancy potential. For this reason, it's important to make up a differential diagnosis between it and the other pancreatic tumors. Unlike the other malignancies, surgical conservative therapy is enough without making great demolitions of the pancreas. Lumpectomy gives a complete cure, decreasing surgical risk and dangerous functional complications. In the present paper, a case of solid papillary tumour of the pancreas is reported. It was diagnosed in a young woman and treated with simple lumpectomy. She is alive and disease free.

Adult↗
PubMed1995

Reciprocal control of inflammatory cytokines, IL-1 and IL-6, and beta-amyloid production in cultures.

To investigate the role of IL-6 in the pathogenesis of Alzheimer's disease (AD) its effect on amyloid precursor protein (APP) mRNA expression was evaluated. The levels of APP mRNA were determined by Northern blot analysis in primary cultured rat cortical neurons and glial cells exposed to IL-6 (50-200 ng/ml). The cytokine increased neuronal APP mRNA expression about 100% at the highest dose after 6 h of exposure. APP mRNA expression was unaffected in astroglial cells exposed to IL-6. Since IL-1 beta also increased neuronal APP mRNA, the combination of IL-1 beta and IL-6 was tested. The effects were partially additive. The ability of beta-amyloid fragment 25-35 to induce IL-1 or IL-6 mRNA was also investigated in astroglial cells. IL-1 beta mRNA was strongly induced by beta 25-35 (25-100 microM) while the expression of IL-6 mRNA remaining unchanged. The results suggest roles for both IL-1 and IL-6 in the neuronal mechanisms related to beta-amyloid protein deposition in AD.

Alzheimer Disease↗