Folding mechanisms steer the amyloid fibril formation propensity of highly homologous proteins

Significant advances in the understanding of the molecular determinants of fibrillogenesis can be expected from comparative studies of the aggregation propensities of proteins with highly homologous structures but different folding pathways. Here, we fully characterize, by means of stopped-flow, T-jump, CD and DSC experiments, the unfolding mechanisms of three highly homologous proteins, zinc binding Ros87 and Ml153-149 and zinc-lacking Ml452-151. The results indicate that the three proteins significantly differ in terms of stability and (un)folding mechanisms. Particularly, Ros87 and Ml153-149 appear to be much more stable to guanidine denaturation and are characterized by folding mechanisms including the presence of an intermediate. On the other hand, metal lacking Ml452-151 folds according to a classic two-state model. Successively, we have monitored the capabilities of Ros87, Ml452-151 and Ml153-149 to form amyloid fibrils under native conditions. Particularly, we show, by CD, fluorescence, DLS, TEM and SEM experiments, that after 168 hours, amyloid formation of Ros87 has started, while Ml153-149 has formed only amorphous aggregates and Ml452-151 is still monomeric in solution. This study shows how metal binding can influence protein folding pathways and thereby control conformational accessibility to aggregation-prone states, which in turn changes aggregation kinetics, shedding light on the role of metal ions in the development of protein deposition diseases

Colorectal Cancer Stage at Diagnosis Before vs During the COVID-19 Pandemic in Italy

IMPORTANCE Delays in screening programs and the reluctance of patients to seek medical attention because of the outbreak of SARS-CoV-2 could be associated with the risk of more advanced colorectal cancers at diagnosis. OBJECTIVE To evaluate whether the SARS-CoV-2 pandemic was associated with more advanced oncologic stage and change in clinical presentation for patients with colorectal cancer. DESIGN, SETTING, AND PARTICIPANTS This retrospective, multicenter cohort study included all 17 938 adult patients who underwent surgery for colorectal cancer from March 1, 2020, to December 31, 2021 (pandemic period), and from January 1, 2018, to February 29, 2020 (prepandemic period), in 81 participating centers in Italy, including tertiary centers and community hospitals. Follow-up was 30 days from surgery. EXPOSURES Any type of surgical procedure for colorectal cancer, including explorative surgery, palliative procedures, and atypical or segmental resections. MAIN OUTCOMES AND MEASURES The primary outcome was advanced stage of colorectal cancer at diagnosis. Secondary outcomes were distant metastasis, T4 stage, aggressive biology (defined as cancer with at least 1 of the following characteristics: signet ring cells, mucinous tumor, budding, lymphovascular invasion, perineural invasion, and lymphangitis), stenotic lesion, emergency surgery, and palliative surgery. The independent association between the pandemic period and the outcomes was assessed using multivariate random-effects logistic regression, with hospital as the cluster variable. RESULTS A total of 17 938 patients (10 007 men [55.8%]; mean [SD] age, 70.6 [12.2] years) underwent surgery for colorectal cancer: 7796 (43.5%) during the pandemic period and 10 142 (56.5%) during the prepandemic period. Logistic regression indicated that the pandemic period was significantly associated with an increased rate of advanced-stage colorectal cancer (odds ratio [OR], 1.07; 95%CI, 1.01-1.13; P = .03), aggressive biology (OR, 1.32; 95%CI, 1.15-1.53; P < .001), and stenotic lesions (OR, 1.15; 95%CI, 1.01-1.31; P = .03). CONCLUSIONS AND RELEVANCE This cohort study suggests a significant association between the SARS-CoV-2 pandemic and the risk of a more advanced oncologic stage at diagnosis among patients undergoing surgery for colorectal cancer and might indicate a potential reduction of survival for these patients

A SCLERODERMA PATIENT WITH SWOLLEN AND TENDER JOINTS OF BOTH HANDS

A 39-year-old woman with a 2-year history of Raynaud’s phenomenon, a previous diagnosis of systemic sclerosis sine scleroderma, and the recent onset of symmetric polyarthritis is reported. Clinical, laboratory, and imaging (radiographs, ultrasonography, and magnetic resonance) features are presented. Treatment and disease course are underlined. Systemic sclerosis articular involvement and its pathologic, clinical, laboratory, imaging, and therapeutic aspects are discussed. The peculiarities of the case are addressed

Structural elucidation of saponins: A combined approach based on high-resolution spectroscopic techniques

Saponins are a group of naturally occurring bioactive compounds often classified in several groups based on their variable structural features. They are constituted by an aglycone or sapogenin (with triterpenoid or steroid skeletons) and one or more sugar chains of different length and branching. Based on their complexity, the structural elucidation of saponins is a very challenging task, requiring the use of several analytical techniques. High-resolution spectroscopic techniques such as nuclear magnetic resonance (NMR) and mass spectrometry (MS) are proved to be valuable tools for the structural characterization of chemicals. In particular, the latest advances in NMR techniques allowed the resolution of highly crowded spectra as those of saponins. These enhancements are especially due to the introduction of new pulse sequences (i.e., heteronuclear single quantum correlation–total correlation spectroscopy, heteronuclear 2-bond correlation, constant time inverse-detected gradient accordion rescaled long-range–heteronuclear multiple bond correlation, etc.) used in combination with more “classical” 1D and 2-D NMR experiments. In addition, the capability of obtaining peculiar fragmentation patterns by ESI-MS (electrospray ionization–MS) and ESI-MSn further allowed the acquisition of complementary structural information of unknown saponins. These spectroscopic techniques are particularly useful tools for the characterization of the oligosaccharide chains without using chemical reactions and/or derivative processes. The combined use of NMR and MS approaches makes it possible to assess the complete and definitive aglycone structure, including stereochemistry, the identification of sugars (ring conformation and size, anomeric configuration), the linkage positions, and sequence of the sugar chain and, in specific cases, the characterization of acyl moieties as well as their linkage positions. In this chapter, the most recent advances in saponin structural elucidation by NMR and MS will be discussed, providing an overview of the potentiality of these techniques for the determination of such complex structures.Saponins are a group of naturally occurring bioactive compounds often classified in several groups based on their variable structural features. They are constituted by an aglycone or sapogenin (with triterpenoid or steroid skeletons) and one or more sugar chains of different length and branching. Based on their complexity, the structural elucidation of saponins is a very challenging task, requiring the use of several analytical techniques. High-resolution spectroscopic techniques such as nuclear magnetic resonance (NMR) and mass spectrometry (MS) are proved to be valuable tools for the structural characterization of chemicals. In particular, the latest advances in NMR techniques allowed the resolution of highly crowded spectra as those of saponins. These enhancements are especially due to the introduction of new pulse sequences (i.e., heteronuclear single quantum correlation-total correlation spectroscopy, heteronuclear 2-bond correlation, constant time inverse-detected gradient accordion rescaled long-range-heteronuclear multiple bond correlation, etc.) used in combination with more "classical" 1D and 2-D NMR experiments. In addition, the capability of obtaining peculiar fragmentation patterns by ESI-MS (electrospray ionization-MS) and ESI-MSn further allowed the acquisition of complementary structural information of unknown saponins. These spectroscopic techniques are particularly useful tools for the characterization of the oligosaccharide chains without using chemical reactions and/or derivative processes. The combined use of NMR and MS approaches makes it possible to assess the complete and definitive aglycone structure, including stereochemistry, the identification of sugars (ring conformation and size, anomeric configuration), the linkage positions, and sequence of the sugar chain and, in specific cases, the characterization of acyl moieties as well as their linkage positions. In this chapter, the most recent advances in saponin structural elucidation by NMR and MS will be discussed, providing an overview of the potentiality of these techniques for the determination of such complex structures

Mortality in Italian patients with rheumatoid arthritis: evidence for a low mortality rate from cancer and infections in patients followed up at a tertiary center

Daniela Iacono, Serena Fasano, Virginia D’Abrosca, Ilenia Pantano, Gabriele Valentini Department of Clinical and Experimental Medicine, Rheumatology Section, University of Campania “Luigi Vanvitelli,” Naples, Italy Objectives: Mortality in patients with rheumatoid arthritis (RA) has never been investigated in Italy. This study is devoted to investigating all the distinct causes of mortality in Italian RA patients.Methods: Clinical charts of patients consecutively admitted to an Italian tertiary center, from January 1, 2008 to December 31, 2014, were reviewed. Mortality rates (incidence mortality rate [IMR] and standardized mortality rate [SMR]) and causes of death as assessed at December 31, 2015, were registered. Mortality rates detected in our series were compared to those reported in other European cohorts and in the general Italian population.Results: Six hundred and eight patients were observed for a median of 3.51 years. Overall IMR was 0.79 deaths/100 person-years. No significant difference between our IMR and that reported in Italian population by the National Institute of Statistics was observed. All-cause and neoplasm IMRs in our series were found to be significantly lower than that reported in the Norfolk Arthritis Registry, while no difference was detected in cardiovascular (CV) mortality. On the other hand, all causes and CV SMRs in our series were found to be higher than that reported in the general Italian population, while cancer and infectious SMRs were found to be lower.Conclusion: In our series, RA patients had an increased all-cause mortality, and in particular an increased death rate due to CV. However, a lower death rate due to cancer and infections was observed. This figure might be due to the careful follow-up of RA patients in tertiary centers, and the results underlines the need to improve the management of CV risk. Keywords: rheumatoid arthritis, mortality, cancer, infections, cardiovascular death

Two new acylated drimane-type sesquiterpene glucosides from Petrorhagia saxifraga

Two new acylated drimane sesquiterpenoid glucosides, saxifragoside A and B, have been isolated from the methanol extract of Petrorhagia saxifraga, a perennial herbaceous plant typical of the Mediterranean vegetation. The structures of these compounds have been elucidated on the basis of extensive 2D NMR spectroscopic analyses, including COSY, TOCSY, NOESY, HSQC, CIGAR-HMBC, H2BC and HSQC-TOCSY, along with Q-TOF HRMS2 analysis. As drimane glucosides have already been reported in other plants of Petrorhagia genus, they could represent a useful chemotaxonomic marker for this genus. © 2013 Published by Elsevier B.V

Seasonal phytochemical changes in Phillyrea angustifolia L.: Metabolomic analysis and phytotoxicity assessment

Plants show seasonality in the secondary metabolite production and the resulting variability can influence plant bioactivity. A study aimed at determining the seasonal metabolic changes in Phillyrea angustifolia and the effects of them on its biological activity has been carried out. The NMR profiles of the extracts obtained from leaves monthly collected from April 2011 to March 2012 revealed a variation of the iridoid content along the year. Oleuropein and the dialdehydic form of decarboxymethyloleuropein (DHPEA-EDA) were the main metabolites present in the extracts. All the extracts have been tested for their phytotoxicity against Triticum ovatum, a P. angustifolia coexisting plant, using a recently proposed metabolomic based approach. Different plant extracts produced a very diverse response in the target plant metabolome. T. ovatum plants treated with plants collected during summer were very similar to the control, while the extracts obtained from leaves collected in winter, containing the highest amount of oleuropein, were the most active against the test species. The metabolic variation detected in different extracts, could be linked to the phoenological stages or induced by environmental stresses (drought, temperature, competition, herbivores, etc.) to which plants are exposed in Mediterranean ecosystems. © 2013 Phytochemical Society of Europe