Luca Scotti

High hydrophobic amino acid exposure is responsible of the neurotoxic effects induced by E200K or D202N disease-related mutations of the human prion protein.

Mutations in prion protein are thought to be causative of inherited prion diseases favoring the spontaneous conversion of the normal prion protein into the scrapie-like pathological prion protein. We previously reported that, by controlled thermal denaturation, human prion protein fragment 90-231 acquires neurotoxic properties when transformed in a β-rich conformation, resembling the scrapie-like conformation. In this study we generated prion protein fragment 90-231 bearing mutations identified in familial prion diseases (D202N and E200K), to analyze their role in the induction of a neurotoxic conformation. Prion protein fragment 90-231(wild type) and the D202N mutant were not toxic in native conformation but induced cell death only after thermal denaturation. Conversely, prion protein fragment 90-231(E200K) was highly toxic in its native structure, suggesting that E200K mutation per se favors the acquisition of a peptide neurotoxic conformation. To identify the structural determinants of prion protein fragment 90-231 toxicity, we show that while the wild type peptide is structured in α-helix, hPrP90-231 E200K is spontaneously refolded in a β-structured conformer characterized by increased proteinase K resistance and propensity to generate fibrils. However, the most significant difference induced by E200K mutation in prion protein fragment 90-231 structure in native conformation we observed, was an increase in the exposure of hydrophobic amino-acids on protein surface that was detected in wild type and D202N proteins only after thermal denaturation. In conclusion, we propose that increased hydrophobicity is one of the main determinants of toxicity induced by different mutations in prion protein-derived peptides.

Dietary Fibers and Cardiometabolic Diseases

The high prevalence of cardiovascular disease (CVD) is largely attributable to the contemporary lifestyle that is often sedentary and includes a diet high in saturated fats and sugars and low ingestion of polyunsaturated fatty acids (PUFAs), fruit, vegetables, and fiber. Experimental data from both animals and humans suggest an association between increased dietary fiber (DF) intakes and improved plasma lipid profiles, including reduced low density lipoprotein cholesterol (LDL-C) concentrations. These observations underline that the intake of DF may protect against heart disease and stroke.

CIRCULATING PLASMA ANTIOXIDANTS, INFLAMMATORY MARKERS AND ASYMPTOMATIC CAROTID ATHEROSCLEROSIS IN END-STAGE RENAL DISEASE PATIENTS: A CASE CONTROL STUDY

Few studies have been conducted on the relationship between antioxidant plasma vitamin concentrations, inflammatory markers and carotid atherosclerosis with inconclusive results in end-stage renal disease (ESRD) patients. A case-control study was performed to investigate the relationship between plasma antioxidant concentrations, inflammatory markers, and carotid intima-media thickness (CIMT) in healthy subjects and in patients undergoing hemodialysis (HD). We enrolled 40 subjects (20 healthy, 20 with ESRD) asymptomatic for carotid atherosclerosis. After carotid ultrasound investigation (CUI), medical history data, physical examination, venous blood samples were collected. These were analyzed for concentrations of antioxidant vitamins (A, E), carotenoids (lycopene, β-carotene), inflammatory markers (C-reactive protein, fibrinogen), and lipid profile. Low concentrations of vitamin A, vitamin E, lycopene, and β-carotene were significantly associated with carotid atherosclerosis in patients with ESRD (p<0.001). In addition, high concentration of low density lipoprotein cholesterol and total cholesterol (p<0.01), C-reactive protein and fibrinogen (p<0.001) were also associated with carotid atherosclerosis, while other laboratory parameters considered (high density lipoprotein cholesterol and triglycerides) were not significantly associated with carotid atherosclerosis. A regular intake of foods rich in antioxidant vitamins with low fat concentrations may slow the progression of atherosclerotic process in this group of patients.

ADMA/SDMA in Elderly Subjects with Asymptomatic Carotid Atherosclerosis: Values and Site-Specific Association

Asymmetric dimethylarginine (ADMA) is an endogenous nitric oxide synthase (NOS) inhibitor known as a mediator of endothelial dysfunction and atherosclerosis. Circulating ADMA levels are correlated with cardiovascular risk factors such as hypercholesterolemia, arterial hypertension, diabetes mellitus, hyperhomocysteinemia, age and smoking. We assessed the relationship between ADMA values and site-specific association of asymptomatic carotid atherosclerosis (intima-media thickness (CIMT) and plaque) in elderly subjects. One hundred and eighty subjects underwent a complete history and physical examination, determination of serum chemistries and ADMA levels, and carotid ultrasound investigation (CUI). All subjects had no acute or chronic symptoms of carotid atherosclerosis. Statistical analyses showed that high plasma levels of ADMA/SDMA were positively correlated to carotid atherosclerosis (CIMT and plaque) (p < 0.001), with significant site-specific association. Total cholesterol, low density lipoprotein cholesterol, triglycerides and C-reactive protein plasma concentrations were significantly associated with asymptomatic carotid atherosclerosis (p < 0.001). High serum concentrations of ADMA and SDMA were associated with carotid atherosclerotic lesions as measured by CIMT ad plaque and may represent a new marker of asymptomatic carotid atherosclerosis in elderly subjects.

Calcium Binding Promotes Prion Protein Fragment 90–231 Conformational Change toward a Membrane Destabilizing and Cytotoxic Structure

The pathological form of prion protein (PrPSc), as other amyloidogenic proteins, causes a marked increase of membrane permeability. PrPSc extracted from infected Syrian hamster brains induces a considerable change in membrane ionic conductance, although the contribution of this interaction to the molecular mechanism of neurodegeneration process is still controversial. We previously showed that the human PrP fragment 90–231 (hPrP90–231) increases ionic conductance across artificial lipid bilayer, in a calcium-dependent manner, producing an alteration similar to that observed for PrPSc. In the present study we demonstrate that hPrP90–231, pre-incubated with 10 mM Ca++ and then re-suspended in physiological external solution increases not only membrane conductance but neurotoxicity as well. Furthermore we show the existence of a direct link between these two effects as demonstrated by a highly statistically significant correlation in several experimental conditions. A similar correlation between increased membrane conductance and cell degeneration has been observed assaying hPrP90–231 bearing pathogenic mutations (D202N and E200K). We also report that Ca++ binding to hPrP90–231 induces a conformational change based on an alteration of secondary structure characterized by loss of alpha-helix content causing hydrophobic amino acid exposure and proteinase K resistance. These features, either acquired after controlled thermal denaturation or induced by D202N and E200K mutations were previously identified as responsible for hPrP90–231 cytotoxicity. Finally, by in silico structural analysis, we propose that Ca++ binding to hPrP90–231 modifies amino acid orientation, in the same way induced by E200K mutation, thus suggesting a pathway for the structural alterations responsible of PrP neurotoxicity.

Effect of 2-year treatment with low-dose rosuvastatin on intima-media thickness in hypercholesterolemic subjects with asymptomatic carotid artery disease

Objectives: Recent evidence indicates that rosuvastatin 40 mg may exert a beneficial effect in both carotid and coronary atherosclerosis progression. In particular, 2-year rosuvastatin treatment reduced the progression of carotid intima-media thickness (cIMT) in patients with low cardiovascular risk. However, despite the fact that in clinical practice lower doses of rosuvastatin are usually administered at this time, there are no clear data about its effect on cIMT. Thus, the aim of this study was to evaluate the effect of rosuvastatin 10 mg/day on cIMT over a 2-year follow-up. Methods: Forty-five patients with hypercholesterolemia and asymptomatic carotid atherosclerosis on baseline carotid ultrasound investigation were treated with rosuvastatin 10 mg/day for 24 months. cIMT and lipid profile were assessed after 12 months and at the end of the study (24 months). Results: After 24 months, the treatment showed a 35.67% reduction in low-density lipoprotein cholesterol concentration (171 vs 110 mg/dl; p < 0.001), a 32.27% reduction in total cholesterol (251 vs 170 mg/dl; p < 0.001), a 19.67% increase in high-density lipoprotein cholesterol concentration (49 vs 61 mg/dl; p < 0.001), and a 10% reduction in triglycerides (120 vs 108 mg/dl; p < 0.01). Rosuvastatin treatment was associated with a 26.6% reduction in left cIMT (1.20 vs 0.90 mm; p < 0.001) and a 22.2% reduction in right cIMT (1.22 vs 0.95 mm; p < 0.001). Conclusion: Two-year treatment with rosuvastatin 10 mg/day in hypercholesterolemic adults with evidence of subclinical atherosclerosis establishes a significant reduction in cIMT and improves lipid and lipoprotein levels, with a good tolerability profile.

Recurrent atrial fibrillation in a patient with ulcerative colitis treated with azathioprine: case report and review of the literature.

We present a clinical case report regarding recurrent atrial fibrillation in a patient with ulcerative colitis treated with azathioprine. Atrial fibrillation represents the most common sustained cardiac arrhythmia, occurring in 1–2% of the general population and characterized by seemingly disorganized atrial depolarizations without effective atrial contraction. Several mechanisms determine this arrhythmia; in particular remodelling (structural, mechanical and electrical alteration related to atrial fibrillation). The pro-arrhythmic effect of azathioprine may be evaluated during immunosuppressive therapy to be aware of this serious but reversible adverse effect.

Dilated cardiomyopathy following use of xenadrine EFX.

We describe a case of a 35-year-old man presented at the emergency room of our institution with acute onset of dyspnea and dizziness. He was a body builder and had been using Xenadrine EFX for weight loss reduction. The laboratory analyses were normal. A chest radiograph showed an enlarged cardiac silhouette with clear lung fields. Transtoracic two-dimensional color Doppler echocardiography revealed a diffuse hypokinesia with a marked decreased in systolic function and a high teledyastolic diameter. This case document the possible relation to use of Xenadrine EFX for weight loss and the recurrence of dilated cardiomyopathy.

Analysis of biologically active oxyprenylated phenylpropanoids in Tea tree oil using selective solid-phase extraction with UHPLC-PDA detection

HIGHLIGHTSOxyprenylated phenylpropanoids as additional components of tea tree oil.Development of an original UHPLC analytical method on tea tree oil.New insights into the therapeutic potential of tea tree oil. ABSTRACT An efficient analytical strategy based on different extraction methods of biologically active naturally occurring oxyprenylated umbelliferone and ferulic acid derivatives 7‐isopentenyloxycoumarin, auraptene, umbelliprenin, boropinic acid, and 4′‐geranyloxyferulic acid and quantification by UHPLC with spectrophotometric (UV/Vis) detection from Tea tree oil is reported. Absorption of the pure oil on Al2O3 (Brockmann activity II) prior washing the resulting solid with MeOH and treatment of this latter with CH2Cl2 resulted the best extraction methodology in terms of yields of oxyprenylated secondary metabolites. Among the five O‐prenylphenylpropanoids herein under investigation auraptene and umbelliprenin were never detected while 4′‐geranyloxyferulic acid was the most abundant compound resulting from all the three extraction methods employed. The UHPLC analytical methodology set up in the present study resulted to be an effective and versatile technique for the simultaneous characterization and quantification of prenyloxyphenylpropanoids in Tea tree oil and applicable to other complex matrices from the plant kingdom.

Electrochemically Synthesized Silver Nanoparticles are Active against Planktonic and Biofilm Cells of Pseudomonas aeruginosa and Other Cystic Fibrosis-Associated Bacterial Pathogens

A novel, electrochemically synthesized, silver nanoparticles (AgNPs) formulation was evaluated in vitro against Pseudomonas aeruginosa, Burkholderia cepacia, Stenotrophomonas maltophilia, and Staphylococcus aureus strains from cystic fibrosis (CF) patients. AgNPs were particularly active against P. aeruginosa and B. cepacia planktonic cells (median MIC: 1.06 and 2.12 μg/ml, respectively) by a rapid, bactericidal and concentration-dependent effect. AgNPs showed to be particularly effective against P. aeruginosa and S. aureus biofilm causing a viability reduction ranging from 50% (1×MIC) to >99.9% (4×MIC). Electron microscopy showed that AgNPs deconstruct extracellular matrix of P. aeruginosa biofilm, and accumulate at the cell surface causing cell death secondary to membrane damage. Compared to Tobramycin, AgNPs showed comparable, or even better, activity against planktonic and biofilm P. aeruginosa cells. AgNPs at concentrations effective against B. cepacia and P. aeruginosa were not toxic to G. mellonella larvae. Our silver-based formulation might be an alternative to antibiotics in CF patients. Further in vitro and in vivo studies are warranted to confirm this therapeutic potential.