Predictive value of computed tomography scoring systems evolution in adults with cystic fibrosis.

OBJECTIVES: To assess whether the evolution of two consecutive high-resolution computed tomography (HRCT) scores in patients with cystic fibrosis (CF) has prognostic value. METHODS: A longitudinal retrospective study was performed to research adult patients with CF. Two consecutive HRCT studies were scored using Bhalla and Brody II scoring scales by two senior radiologists. Annual scoring changes for each scale were calculated and correlated with annual FEV1% decline, with pulmonary exacerbations and number of antibiotic treatments. RESULTS: We selected sixty-four adult patients. The median interval between the two HRCTs was 3.88 ± 1.59 years. The mean spirometric values showed dynamic lung volumes lower than the general population; globally, there was a worsening of respiratory function over time. The change in the annual HRCT scores was positive on both scales, indicating a worse structural situation over time. The Brody II scale annual change showed a significant statistical correlation with a decline in the annual FEV1%, exacerbations and number of oral antibiotic treatments. In contrast, for the Bhalla scale, the relationship was moderately inverse with exacerbations and with the number of oral treatments. No statistically significant relationships were found for the change in the annual FEV1% and exacerbations or number of antibiotic treatments. The interobservational and intraobservational agreements were very strong in both scales. CONCLUSIONS: The annual evolution of the Brody II HRCT scoring system demonstrated a predictive value and correlated with FEV1% decline, pulmonary exacerbations and oral antibiotic treatments. KEY POINTS: • HRCT evolution has prognostic value in cystic fibrosis. • Temporal evolution for the Brody II score is useful for clinical follow-up. • Brody II score changes correlate with FEV1% decline, pulmonary exacerbations and number of antibiotic treatments.

Sexual Dysfunction and Quality of Life in Chronic Heroin-Dependent Individuals on Methadone Maintenance Treatment.

This study examined whether methadone (hereinafter referred to as MTD) maintenance treatment (MMT) is correlated with sexual dysfunction (SD) in heroin-dependent men. This was conducted to determine the prevalence of sexual dysfunction and if there is a relationship between duration and dose among men on MMT and its impact on the quality of life. The study combined a retrospective and a cross-sectional survey based on the Kinsey Scale, TECVASP, and PRSexDQ-SALSEX clinical interviews of 85 patients who are currently engaged in MMT. Sexual dysfunction in all five PRSexDQ-SALSEX domains (lack of libido, delay in orgasm, inability to orgasm, erectile dysfunction, and tolerance or acceptance of changes in sexual function) was associated with dose and long-term use of heroin. All dimensions of SD were affected by the MTD intake. From the analysis of our sample, we may conclude that dose of MTD and overall score of SD were directly associated. However, no evidence was found to prove that treatment duration and severity of SD were linked. It is notable that only one tenth of the patients spontaneously reported their symptoms of the sexual sphere, but up to a third considered leaving the MMT for this reason.

Desaturations During 6-Minute Walk Test and Predicting Nocturnal Desaturations in Adult Subjects With Cystic Fibrosis.

BACKGROUND: Nocturnal desaturation in cystic fibrosis (CF) may have prognostic implications because a significant and maintained nocturnal desaturation can contribute to the development and progression of pulmonary hypertension with cor pulmonale. Its relation with the desaturation in exercise has not been sufficiently studied. We aimed to determine whether desaturation during 6MWT can be an indicator of nocturnal desaturation in adult subjects with CF. METHODS: 57 subjects were included: 50.9% male, 27.5 ± 7.7 y old, mean FEV1 = 2.37 ± 0.74 L, and %FEV1 67 ± 18.1%. Desaturation during 6MWT was defined as oxygen saturation (SpO2 ) ≤ 90% or a decline of > 4 points in SpO2 from baseline, and nocturnal desaturation as a desaturation index > 4 or > 5% of sleep time with SpO2 ≤ 90%. RESULTS: Desaturation observed during 6MWT in adult subjects with CF did not correlate with nocturnal desaturation (P = .27). Subjects with %FEV1 ≤ 55% and diffusion capacity of carbon monoxide (DLCO) ≤ 50 mmol/min/mm Hg were at higher risk of 6MWT desaturation. Nocturnal desaturation was more frequent in males, with PaO2 ≤ 71 mm Hg in blood gas analysis. CONCLUSIONS: Desaturation observed in 6MWT cannot predict desaturation at night in adults with CF. Other parameters were identified as predictors of desaturation.

New strategy for the generation of specific D-peptide amyloid inhibitors.

The conversion of a soluble protein into beta-sheet-rich oligomeric structures and further fiber formation are critical steps in the pathogenesis of the group of human diseases known as amyloidoses. Drugs that interfere with this process may thus be able to prevent and/or cure these diseases. Recent results have shown that short amino acid stretches can provide most of the driving force needed to trigger amyloid formation of a protein. These evidence suggest that compounds that specifically bind to peptides synthesized upon the sequence of such amyloidogenic protein stretches might also be able to inhibit amyloid formation of the corresponding full-length protein and, likely, amyloid-induced cytotoxicity as well. Here we present a general strategy to obtain d-peptides that specifically interact with protein amyloid stretches. The screening of a d-peptide combinatorial library for inhibitors of an amyloidogenic peptide designed de novo has allowed us to extract a set of empirical rules for the design of d-peptide inhibitors of any six-residue amyloidogenic stretch. d-peptides generated on these bases prevent amyloid formation and disassemble preformed fibrils of different amyloid hexapeptides identified in human amyloid proteins. In addition, they are also specific for their target sequence. The d-peptide designed here for the Alzheimer's Abeta(1-42) peptide not only inhibits and disassembles amyloid material but also reduces Abeta(1-42) amyloid-induced cytotoxicity in cell culture.

Design of a bivalent peptide with two independent elements of secondary structure able to fold autonomously.

This article describes a strategy to develop, starting from a de novo design, bivalent peptides containing two different (alpha-helix and beta-hairpin) and independent secondary-structure elements. The design was based on the use of conformationally restricted peptide libraries. Structural characterization by NMR revealed that the peptides were stable and did not show any long-range NOE interactions between the N-terminal beta-hairpin and the C-terminal alpha-helix. These results suggest that the two elements of secondary structure are stable and well folded.

Amyloid toxicity is independent of polypeptide sequence, length and chirality.

By using an amyloid sequence pattern, here we have identified putative six-residue amyloidogenic stretches in several relevant amyloid proteins. Hexapeptides synthesized on the bases of the sequence stretches matching the pattern have been shown to form amyloid fibrils in vitro. As larger pathological peptides such as A beta(1-42) do, these short amyloid peptides form heterogeneous mixtures of small aggregates that induce cell death in PC12 cells and primary hippocampal neurons. Toxic mixtures of small aggregates from these hexapeptides bind to cell membranes and can be further internalized, as also observed for natural amyloid proteins. In neurons, toxic aggregates obtained from the full length A beta(1-42) amyloid peptide or their amyloid stretch A beta(16-21) peptide preferentially localize in synapses, leading to the re-organization of the underlying actin cytoskeleton. This process does not involve stereospecific interactions between membrane and toxic species as D-sequences are as toxic as L ones, suggesting that is not receptor mediated. Based on these results, we propose here that regardless of polypeptide sequence, length and amino acid chirality, amyloid prefibrillar aggregates exert their cytotoxic effect through a common cell death mechanism related to a particular quaternary structure. The degree of toxicity of these species seems to depend, however, on cell membrane composition.

Hacking the code of amyloid formation: the amyloid stretch hypothesis.

Many research efforts in the last years have been directed towards understanding the factors determining protein misfolding and amyloid formation. Protein stability and amino acid composition have been identified as the two major factors in vitro. The research of our group has been focused on understanding the relationship between amino acid sequence and amyloid formation. Our approach has been the design of simple model systems that reproduce the biophysical properties of natural amyloids. An amyloid sequence pattern was extracted that can be used to detect amyloidogenic hexapeptide stretches in proteins. We have added evidence supporting that these amyloidogenic stretches can trigger amyloid formation by nonamyloidogenic proteins. Some experimental results in other amyloid proteins will be analyzed under the conclusions obtained in these studies. Our conclusions together with evidences from other groups suggest that amyloid formation is the result of the interplay between a decrease of protein stability, and the presence of highly amyloidogenic regions in proteins. As many of these results have been obtained in vitro, the challenge for the next years will be to demonstrate their validity in in vivo systems.

Design of bioactive and structurally well-defined peptides from conformationally restricted libraries.

Libraries of peptides and proteins can be categorized according to the function of their origin in gene- and synthetic-based libraries. Both kinds of libraries have the potential to generate the same grade of molecular diversity, although the limits imposed by the synthetic methods have been lately a matter of discussion. However, the use of synthetic strategies allows incorporation of non-natural amino acids. The development of conformationally restricted synthetic peptide libraries can be considered as a point of convergence of the two methodologies. In these libraries the diversity is grafted into scaffolds that are defined by stable secondary structural motifs, and the deconvolution protocols can be directed towards the identification of biologically active molecules and the analysis of determinants of folding of protein domains.

Combinatorial chemistry of beta-hairpins.

Combinatorial chemistry is expanding rapidly both in terms of chemistry development and application to the synthesis of compound libraries for lead discovery and optimization. Combinatorial technologies continue evolving and developing, in fact they are being used as basic research tools in different fields that include peptide/protein folding. This review examines the use of combinatorial chemistry in the design of peptides and protein domains that adopt beta-sheet conformations. In particular, the use of conformationally restricted peptide libraries has allowed the identification of linear peptides that are folded in a beta-hairpin structure in plain aqueous solutions.