Smart Electrospun Nanofibers from Short Peptidomimetics Based on Pyrrolo-pyrazole Scaffold.

We prepared a small library of short peptidomimetics based on 3-pyrrolo-pyrazole carboxylate, a non-coded γ-amino acid, and glycine or alanine. The robust and eco-friendly synthetic approach adopted allows to obtain the dipeptides in two steps from commercial starting materials. This gives the possibility to shape these materials by electrospinning into micro- and nanofibers, in amounts required to be useful for coating surfaces of biomedical relevance. To promote high quality of electrospun fibers, different substitution patterns were evaluated, all for pure peptide fibers, free of any polymer or additive. The best candidate, which affords a homogeneous fibrous matrix, was prepared in larger amounts, and its biocompatibility was verified. This successful work is the first step to develop a new biomaterial able to produce pristine peptide-based nanofibers to be used as helpful component or stand-alone scaffolds for tissue engineering or for the surface modification of medical devices.

Spatial Multiomics of Lipids, N-Glycans, and Tryptic Peptides on a Single FFPE Tissue Section.

Mass spectrometry imaging (MSI) is an emerging technology that is capable of mapping various biomolecules within their native spatial context, and performing spatial multiomics on formalin-fixed paraffin-embedded (FFPE) tissues may further increase the molecular characterization of pathological states. Here we present a novel workflow which enables the sequential MSI of lipids, N-glycans, and tryptic peptides on a single FFPE tissue section and highlight the enhanced molecular characterization that is offered by combining the multiple spatial omics data sets. In murine brain and clear cell renal cell carcinoma (ccRCC) tissue, the three molecular levels provided complementary information and characterized different histological regions. Moreover, when the spatial omics data was integrated, the different histopathological regions of the ccRCC tissue could be better discriminated with respect to the imaging data set of any single omics class. Taken together, these promising findings demonstrate the capability to more comprehensively map the molecular complexity within pathological tissue.

Cytomolecular Classification of Thyroid Nodules Using Fine-Needle Washes Aspiration Biopsies.

Fine-needle aspiration biopsies (FNA) represent the gold standard to exclude the malignant nature of thyroid nodules. After cytomorphology, 20-30% of cases are deemed "indeterminate for malignancy" and undergo surgery. However, after thyroidectomy, 70-80% of these nodules are benign. The identification of tools for improving FNA's diagnostic performances is explored by matrix-assisted laser-desorption ionization mass spectrometry imaging (MALDI-MSI). A clinical study was conducted in order to build a classification model for the characterization of thyroid nodules on a large cohort of 240 samples, showing that MALDI-MSI can be effective in separating areas with benign/malignant cells. The model had optimal performances in the internal validation set (n = 70), with 100.0% (95% CI = 83.2-100.0%) sensitivity and 96.0% (95% CI = 86.3-99.5%) specificity. The external validation (n = 170) showed a specificity of 82.9% (95% CI = 74.3-89.5%) and a sensitivity of 43.1% (95% CI = 30.9-56.0%). The performance of the model was hampered in the presence of poor and/or noisy spectra. Consequently, restricting the evaluation to the subset of FNAs with adequate cellularity, sensitivity improved up to 76.5% (95% CI = 58.8-89.3). Results also suggest the putative role of MALDI-MSI in routine clinical triage, with a three levels diagnostic classification that accounts for an indeterminate gray zone of nodules requiring a strict follow-up.

Ex vivo thyroid fine needle aspirations as an alternative for MALDI-MSI proteomic investigation: intra-patient comparison.

Fine needle aspiration (FNA) is the reference standard for the diagnosis of thyroid nodules. Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) has been successfully used to discriminate the proteomic profiles of benign and malignant thyroid FNAs within the scope of providing support to pathologists for the classification of morphologically borderline cases. However, real FNAs provide a limited amount of material due to sample collection restrictions. Ex vivo FNAs could represent a valuable alternative, increasing sample size and the power of statistical conclusions. In this study, we compared the real and ex vivo MALDI-MSI proteomic profiles, extracted from thyrocyte containing regions of interest, of 13 patients in order to verify their similarity. Statistical analysis demonstrated the mass spectra similarity of the proteomic profiles by performing intra-patient comparison, using statistical similarity systems. In conclusion, these results show that post-surgical FNAs represent a possible alternative source of material for MALDI-MSI proteomic investigations in instances where pre-surgical samples are unavailable or the number of cells is scarce.

Rational Design of a User-Friendly Aptamer/Peptide-Based Device for the Detection of Staphylococcus aureus.

The urgent need to develop a detection system for Staphylococcus aureus, one of the most common causes of infection, is prompting research towards novel approaches and devices, with a particular focus on point-of-care analysis. Biosensors are promising systems to achieve this aim. We coupled the selectivity and affinity of aptamers, short nucleic acids sequences able to recognize specific epitopes on bacterial surface, immobilized at high density on a nanostructured zirconium dioxide surface, with the rational design of specifically interacting fluorescent peptides to assemble an easy-to-use detection device. We show that the displacement of fluorescent peptides upon the competitive binding of S. aureus to immobilized aptamers can be detected and quantified through fluorescence loss. This approach could be also applied to the detection of other bacterial species once aptamers interacting with specific antigens will be identified, allowing the development of a platform for easy detection of a pathogen without requiring access to a healthcare environment.

Tetrahydro-4 H-(pyrrolo[3,4- d]isoxazol-3-yl)methanamine: A Bicyclic Diamino Scaffold Stabilizing Parallel Turn Conformations.

A tetrahydro-4 H-(pyrrolo[3,4- d]isoxazol-3-yl)methanamine scaffold was designed as a diamino derivative to stabilize parallel turn conformations. Its synthesis took advantage of a [1,3]-dipolar cycloaddition reaction between the nitrile oxide derived from the inexpensive enantiopure l -phenylalanine and N-benzyl-3-pyrroline. Two diastereoisomers were formed, whose distribution depends on the selected base. 3a R,6a S-Isomer is favored in organic bases, which formation is driven by π-interactions. However, the above interactions were significantly prevented using an inorganic base due to the chaotropic effect of the cation, decreasing the amount of the above isomer. Finally, we demonstrated that this isomer is able to stabilize parallel turn conformations when inserted in short peptide sequences.

Tandem Tetrahydroisoquinoline-4-carboxylic Acid/ß-Alanine as a New Construct Able To Induce a Flexible Turn.

Tetrahydroisoquinoline-4-carboxylic acid, a constrained ß2 -amino acid named ß-TIC, was synthesised for the first time in enantiopure form. The biocatalytic route applied herein represents one of the few successful examples of enzymatic resolution of ß2 -amino acids. Model tetrapeptides, namely, Fmoc-l-Ala-ß-TIC-ß-Ala-l-Val-OBn (Fmoc=fluorenylmethyloxycarbonyl, Bn=benzyl), containing both isomers of ß-TIC, were prepared. Both computational and NMR spectroscopy studies were performed. A reverse-turn conformation was observed in the case of (R)-ß-TIC enantiomer that was obtained in 99 % enantiomeric excess by enzymatic resolution. The ß-TIC/ß-Ala construct represents the first example of a flexible turn mimetic containing a cyclic and an acyclic ß-amino acid. Furthermore, the presence of an aromatic ring of ß-TIC could facilitate non-covalent interactions to increase the potential of this scaffold for the preparation of protein-protein interaction modulators.

Body Mass Index Predicts Progression of Mild Cognitive Impairment to Dementia.

AIMS: To examine the relationship between body mass index (BMI) and progression to dementia and Alzheimer's disease (AD) in mild cognitive impairment (MCI). MATERIALS AND METHODS: Two hundred and twenty-eight MCI subjects (mean age 74.04 ± 6.94 years; 57% female) from a memory clinic were followed for 2.40 ± 1.58 years. Baseline height and weight were used to calculate the BMI. The main outcome was progression to dementia (DSM-IV criteria) and AD (NINCDS-ADRDA criteria). Cox proportional hazard models were used to assess the longitudinal association of BMI with dementia and AD, adjusting for a comprehensive set of covariates, including vascular risk factors/diseases and neuroimaging profiles. RESULTS: Out of 228 subjects with MCI, 117 (51.3%) progressed to dementia. Eighty-nine (76%) of the incident dementia cases had AD. In both unadjusted and multi-adjusted models, a higher BMI was associated with a reduced risk of dementia (multi-adjusted HR 0.9; 95% CI 0.8-0.9) and AD (multi-adjusted HR 0.9; 95% CI 0.8-0.9). Being underweight increased the risk of all types of dementia (multi-adjusted HR 2.5; 95% CI 1.2-5.1) but was not specifically associated with AD (multi-adjusted HR 2.2; 95% CI 0.9-5.3). CONCLUSIONS: BMI predicted progression of MCI to dementia and AD. In particular, a higher BMI was associated with a lower risk of dementia and AD, and underweight was associated with a higher risk of dementia. BMI assessment may improve the prognostic accuracy of MCI in clinical practice.

Unusual chemoselective Rh(II)-catalysed transformations of α-diazocarbonyl piperidine cores.

The reactivity of various α-diazocarbonyl piperidine scaffolds, characterised by an increased molecular complexity, was tested with various Rh(II) catalysts. The structure of the starting reagent is of relevance to the synthetic results. An unexpected dimerisation took place, starting from the simple piperidine scaffold, to give the hexahydrotetrazine ring system. Products derived from a nitrogen ylide intermediate or aromatic substitution (1,3,4,5-tetrahydro-2,5-methanobenzo[c]azepine and 1,2,3,3a-tetrahydrocyclopenta[de]isoquinolin-4(5 H)-one rings, respectively) were obtained from tetrahydroisoquinoline derivatives. The chemoselectivity of the reaction could be controlled by the choice of starting reagent, Rh(II) catalyst and the reaction conditions. Finally, it was found that the azepino heterocycle could coordinate to the catalyst to give new Rh(II) complexes.

1H-Azepine-2-oxo-5-amino-5-carboxylic Acid: A 310 Helix Inducer and an Effective Tool for Functionalized Gold Nanoparticles.

A new α,α-disubstituted constrained glutamine analogue has been designed to decorate gold nanoparticles and to induce a 310-helix when inserted in peptides. Using an efficient "one-pot" asymmetric Schmidt reaction between 4-disubstituted-cyclohexanone and hydroxyalkylazides, 1H-azepine-2-oxo-5-amino-5-carboxylic acid was prepared. The main (R) isomer was inserted at the N-terminus in a very short peptide sequence (i.e., PhCO-(R)-Oxo-Azn-L-Ala-Aib-L-AlaNHMe) and a stable 310-helix conformation was obtained, as verified by both NMR experiments and molecular dynamics (MD) simulations. Finally, the presence of the hydroxyl chain at the nitrogen atom of the ring allowed for the preparation of covered chiral gold nanoparticles.

MediaChrom: Discovering a Class of Pyrimidoindolone-Based Polarity-Sensitive Dyes.

A small library of six polarity-sensitive fluorescent dyes, nicknamed MediaChrom, was prepared. This class of dyes is characterized by a pyrimidoindolone core fitted out with a conjugated push-pull system and a carboxy linker for a conceivable coupling with biomolecules. The optimized eight-step synthetic strategy involves a highly chemo- and regioselective gold-catalyzed cycloisomerization reaction. The photophysical properties of MediaChrom dyes have been evaluated in-depth. In particular, the MediaChrom bearing a diethylamino as an electron-donating group and a trifluoromethyl as an electron-withdrawing group displays the most interesting and advantageous spectroscopic features (e.g., absorption and emission in the visible range and a good quantum yield). Promising results in terms of sensitivity have been obtained in vitro on this dye as a membrane/lipophilic probe and as a peptide fluorescent label.

Stereochemical Behavior of Pyrrolo-Pyrazole Peptidomimetics Promoting Phase-Selective Supramolecular Organogels.

Supramolecular gels were developed by taking advantage of an assembly of small dipeptides containing pyrrolo-pyrazole scaffolds. The dipeptides were prepared through a robust and ecofriendly synthetic approach from the commercially available starting materials of diazoalkanes and maleimides. By playing with the functionalization of the scaffold, the choice of the natural amino acid, and the stereochemistry, we were able to obtain phase-selective gels. In particular, one peptidomimetic showed gelation ability and thermoreversibility in aromatic solvents at very low concentrations. Rheology tests showed a typical viscoelastic solid profile, indicating the formation of strong gels that were stable under high mechanical deformation. NMR studies were performed, allowing us to determine the conformational and stereochemical features at the base of the supramolecular interactions.

The SIRT2 polymorphism rs10410544 and risk of Alzheimer's disease in two Caucasian case-control cohorts.

BACKGROUND: Human sirtuins are a current hotspot for research in neurodegenerative disorders, including Alzheimer's disease (AD). This study investigated whether genetic variants in two members of the sirtuin family, SIRT2 and SIRT3, affected AD susceptibility. METHODS: A genetic case-control study was performed, comprising 534 probable AD cases and 638 nondemented control subjects from the north of Italy and Canton Ticino, Switzerland (discovery population). The study was focused on SIRT2 rs10410544, SIRT3 rs4980329, and SIRT3 rs536715 single nucleotide polymorphisms (SNPs). These SNPs were genotyped by real-time polymerase chain reaction allelic discrimination assay or restriction fragment length polymorphism. The SNPs rs7412 and rs429358, mapping within the apolipoprotein E (APOE) gene, were genotyped by real-time polymerase chain reaction allelic discrimination assay too. In a replication population comprising 756 AD cases and 847 nondemented control subjects, SIRT2 rs10410544, APOE rs7412, and APOE rs429358 were genotyped as mentioned previously. RESULTS: In the discovery population, we observed an association between SIRT2 rs10410544 T allele and AD (adjusted odds ratio [OR] = 1.23, 95% confidence interval [CI]: 1.02-1.50, P = .02, after correction for sex, age, and APOE ε4 genotype). The association between AD and SIRT2 rs10410544 T allele was only present in APOE ε4 noncarriers (adjusted OR = 1.29, 95% CI: 1.03-1.61, P = .03). The replication study did not confirm this evidence. However, the combined analysis on the two cohorts detected the association (adjusted OR = 1.17, 95% CI: 1.02-1.35, P = .02), and only APOE ε4 noncarriers were at risk (adjusted OR = 1.2, 95% CI: 1.02-1.43, P = .03). CONCLUSIONS: The SIRT2 rs10410544 T allele deserves further investigation as a novel minor genetic risk factor for AD in the APOE ε4-negative Caucasian population.

1H-Azepine-4-amino-4-carboxylic acid: a new α,α-disubstituted ornithine analogue capable of inducing helix conformations in short Ala-Aib pentapeptides.

A very efficient synthesis of orthogonally protected 1H-azepine-4-amino-4-carboxylic acid, abbreviated as Azn, a conformationally restricted analogue of ornithine, was realized. It was obtained on a gram scale in good overall yield in five steps, three of which did not require isolation of the intermediates, starting from the readily available 1-amino-4-oxo-cyclohexane-4-carboxylic acid. Both enantiomers were used for the preparation of pentapeptide models containing Ala, Aib, and Azn. Conformational studies using both spectroscopic techniques (NMR, CD) and molecular dynamics on model 5-mer peptides showed that the (R)-Azn isomer possesses a marked helicogenic effect.

Expedient chemical synthesis of 75mer DNA binding domain of MafA: an insight on its binding to insulin enhancer.

An expedient chemical synthesis of a 75mer peptide corresponding to the DNA binding domain (DBD, 227-301) of the human MafA leucine zipper transcription factor is reported. The application of microwave-assisted solid phase peptide synthesis (MW-SPPS) with a protocol modified respect to the standard one allowed obtaining the desired 75mer peptide in a short time with high quantity and optimal purity. MW-SPPS methodology was thus demonstrated as a valuable alternative to recombinant methods to obtain protein domains. Considering that recent findings suggest an involvement of MafA in the pathogenesis of diabetes mellitus, we also performed circular dichroism studies both on DBD folding and its interaction with MafA recognition element (MARE) on insulin enhancer. From our results, it was evicted that a disorder to order transition occurs after DBD interaction with insulin MARE which is mediated by specific structural elements on the N-terminus of the DBD.

Does vascular burden contribute to the progression of mild cognitive impairment to dementia?

AIMS: To investigate the contribution of vascular risk factors (VRFs), vascular diseases (VDs) and white matter lesions (WMLs) to the progression of mild cognitive impairment (MCI) to dementia and Alzheimer's disease (AD). METHODS: Two hundred forty-five consecutive subjects with MCI (age 74.09 ± 6.92 years) were followed for an average of 2.4 years. The Hachinski Ischemic Score and the Framingham Stroke Risk Profile were used to summarize VRFs and VDs. WMLs were graded using the Age-Related White Matter Changes Scale. RESULTS: One hundred twenty-nine (52.6%) out of 245 subjects at risk converted to dementia, including 87 cases of AD. When hypertension occurred in MCI with deep WMLs, a 1.8-fold increased risk of dementia was observed (95% CI = 1.0-3.4). When deep WMLs occurred in MCI with high scores (≥4) on the Hachinski scale, a 3.5-fold (95% CI = 1.6-7.4) and 3.8-fold (95% CI = 1.2-11.5) risk of progression to dementia and AD was observed, respectively. Analogously, the joint effect of WMLs and high scores (≥14) on the Framingham scale nearly doubled the risk of dementia (hazard ratio = 1.9, 95% CI = 1.1-3.3). CONCLUSIONS: Accelerated progression of MCI to dementia and AD is to be expected when VRFs and VDs occur together with WMLs.

Closing-in behavior in mild cognitive impairment: an executive deficit.

This study explored Closing-in behavior (CIB), the tendency in figure copying to draw very close to or on top of the model, in mild cognitive impairment (MCI). The files of 154 people diagnosed with MCI were reviewed and CIB was identified in 21% of cases. Two approaches were used to explore CIB. First, we capitalized on the diverse cognitive profiles within MCI, subdividing the overall sample into people with and without memory deficits. The frequency of CIB was significantly higher in multidomain non-amnestic MCI than in multidomain amnestic MCI, suggesting that CIB is not associated with specific memory impairment. Second, we assessed the cognitive correlates of CIB, by selecting patients with MCI who completed a battery of executive, visuo-constructional and memory tasks. Sub-groups of patients with and without CIB showed a similar overall severity of cognitive decline and comparable performance in visuo-constructional and memory tasks, but those with CIB were slightly but significantly more impaired on executive function tasks. The study provides evidence against memory-based accounts of CIB, and supports recent suggestions that executive impairments are the dominant cognitive correlate of this clinical sign.

Memantine effects on behaviour in moderately severe to severe Alzheimer's disease: a post-marketing surveillance study.

The aim of this study is to evaluate memantine effectiveness on behavioural and psychological symptoms of dementia (BPSD) in clinical practice and to identify variables that may predict the therapy effects. The effects of memantine on behaviour were analysed in the database of a post-marketing surveillance study promoted by the Lombardy Region Health Office and involving 43 Alzheimer's disease (AD) Units. From July to December 2005, 399 moderately severe-to-severe AD patients free of cholinergic medications were enrolled, treated with memantine and followed-up for 6 months. BPSD were assessed in a subgroup of 297 patients [mean age 77 ± 8 years; 73% females; mean neuropsychiatric inventory (NPI) score 28 ± 24] for whom the 12-item NPI subscores at baseline, and at 3 and 6 months were available. The 12 BPSD were clustered as follows: affect, physical behaviour, psychosis and hypomania. The main outcome measure was the proportion of individual cluster responders at 6 months of therapy. The proportion of individual cluster responders was 30% affect, 24% physical behaviour, 29% psychosis, 27% hypomania. Patients taking 20 mg memantine daily during the study period had a statistically significant higher probability to experience behavioural improvement than those who discontinued treatment or did not complete memantine titration (affect OR 9.0; 95% CI 3.8-21.6; physical behaviour OR 17.8; 95% CI 5.9-53.6; psychosis OR 23.6; 95% CI 5.1-110.8). The logistic regression analysis was not applicable to the hypomania subsyndrome because of the low cluster prevalence. The standard 20 mg daily memantine treatment regimen was found to be associated with a modest 6-month behavioural improvement in the affect, physical behaviour and psychosis domains in 24-30% of patients.

Position paper of the Italian Society for the study of Dementias (SINDEM) on the proposal of a new lexicon on Alzheimer disease.

A panel of Italian neurologists of the Italian Society for the study of Dementias (SINDEM) discussed the recently proposed new lexicon for Alzheimer disease (AD) and the related diagnostic criteria for the different phases of the disease (Preclinical AD, prodromal AD and Alzheimer's dementia) (Dubois et al. in Lancet Neurol 6:734-746, 2007; in Lancet Neurol 9:1118-1127, 2010). The aim of this discussion was to reach a consensus, among the Italian neurologists involved in the study and care of persons with dementia, in particular in reference to the potential use of the proposed diagnostic criteria in clinical practice. After having critically revised the scientific evidence related to the new lexicon and to the new proposed diagnostic criteria, the panel concluded that the proposed new diagnostic criteria and the new proposed lexicon for AD are conceptually attractive. However, the evidence about the instrumental and laboratory markers for the diagnosis of the preclinical and asymptomatic states of the disease are, until to now, insufficient to support the routine clinical use of these investigations.