Binding of disaccharides by peanut agglutinin as studied by ultraviolet difference spectroscopy

The binding of the disaccharides methyl \u3b2-d-lactoside and 2-acetamido-2-deoxy-3-O-(\u3b2-d-galactopyranosyl)- \u3b2-dD-galactopyranose [\u3b2-d-Gal-(l\u21923)-d-GalNAc] to peanut agglutinin was studied by ultraviolet difference spectroscopy. The magnitude of the difference spectra varied with the concentration of the carbohydrates; association constants and thermodynamic parameters were determined from titration experiments at different temperatures. The enthalpy and entropy changes for binding of methyl \u3b2-d-lactoside were found to be \u394H\ub0= -65 \ub1 4 kJ mol 121, \u394Sdeg; = 12156 \ub1 14 J mol 121 K 121. For \u3b2-dD-Gal- (1\u21923)-d-Gal NAc the observed thermodynamic parameters were \u394H\ub0= 1278 \ub1 kJ mol 121, \u394S\ub0= 12177 \ub1 16 J mol 121 K 121. For both disaccharides, the enthalpy change upon binding to the lectin is much larger than that found for the binding of methyl \u3b1- and \u3b2-d-galactopyranosides, strongly suggesting the existence of an extended binding site on peanut agglutinin. The observed parameters are compared with those found for the binding of monosaccharides and oligosaccharides to other lectins and to lysozymc. Molecular models of the minimum energy conformers of \u3b2-GaI-(1\u21923)-d-GalNAc and methyl \u3b2-d-Iactoside are used to interpret the interaction of these, and structurally related ligands, with the peanut agglutinin binding site.Peer reviewed: YesNRC publication: Ye

Carbon-13 nuclear magnetic resonance studies on lectin-carbohydrate interactions: binding of specifically carbon-13-labeled methyl .beta.-D-lactoside to peanut agglutinin

The binding of methyl \u3b2-D-lactoside, specifically \ub9\ub3C-labeled at C-1 of the D-galactose residue, to peanut agglutinin was studied by carbon-13 nuclear magnetic resonance. The high level of \ub9\ub3C enrichment and the high magnetic field employed allowed studies at low ligand concentrations and provided simple single line spectra of very good signal to noise ratios. The \ub9\ub3C-l resonance of the disaccharide shows line broadening upon binding to the lectin, which was inhibited by an excess of an unlabeled competitive binding sugar. Between 10 and 30\ubaC, the disaccharide was found to be in slow exchange with the protein. Residence times, rM, dissociation rate constants, kdiss, and association equilibrium constants were obtained from a study of the \ub9\ub3C-l line width of the disaccharide in the presence of the protein. Dissociation rate constants for the disaccharide were similar in magnitude to those found for the \u3b1 and \u3b2 anomers of methyl D-galactoside but showed a steeper temperature dependence. The activation enthalpy for dissociation, 13.4 kcal mol\u207b\ub9, is larger than that for methyl \u3b2-D-galactopyranoside, while the activation entropy is less negative. The free energy of activation for dissociation is very close to that for both methyl \u3b1- and \u3b2-D-galactopyranoside. The association rate constants for the disaccharide at different temperatures, as calculated from the dissociation rate constants and from association constants determined independently, are also very similar to those found for the monosaccharide. The association activation parameters, \u394H\u207a = -3.5 kcal mol\u207b\ub9 and T\u394S\u207a = -14.6 kcal mol\u207b\ub9, and the fact that the activation enthalpy for dissociation is smaller than the total enthalpy change are further evidence for the previously proposed two-step model for the binding of saccharides to peanut agglutinin. The larger dissociation activation enthalpy and total enthalpy change on binding of the disaccharide, as compared to the monosaccharide, indicate an extended binding site on peanut agglutinin.Peer reviewed: YesNRC publication: Ye

General measures and supportive therapy for pulmonary arterial hypertension: Updated recommendations from the Cologne Consensus Conference 2018

In the summer of 2016, delegates from the German Respiratory Society, the German Society of Cardiology and the German Society of Pediatric Cardiology met in Cologne, Germany, to define consensus-based practice recommendations for the management of patients with pulmonary arterial hypertension (PAH). These recommendations were built on the 2015 European Pulmonary Hypertension guidelines aiming at their practical implementation, considering country-specific issues, and including new evidence, where available. To this end, a number of working groups was initiated, one of which was specifically dedicated to general measures (i.e. physical activity/supervised rehabilitation, pregnancy/contraception, elective surgery, infection prevention, psychological support, travel) and supportive therapy (i.e. anticoagulants, diuretics, oxygen, cardiovascular medications, anaemia/iron deficiency, arrhythmias) for PAH. While the European guidelines provide detailed recommendations for the use of targeted PAH therapies as well as supportive care, detailed treatment decisions in routine clinical care may be challenging, and the relevance of supportive care is often not sufficiently considered. In addition, new evidence became available, thus requiring a thorough reevaluation of specific recommendations. The detailed results and recommendations of the working group on general measures and supportive therapy for PAH, which were last updated in the spring of 2018, are summarized in this article. (c) 2018 Elsevier B.V. All rights reserved

Long-term safety of pirfenidone: results of the prospective, observational PASSPORT study

Real-world studies include a broader patient population for a longer duration than randomised controlled trials (RCTs) and can provide relevant insights for clinical practice. PASSPORT was a multicentre, prospective, post-authorisation study of patients who were newly prescribed pirfenidone and followed for 2 years after initiating treatment. Physicians collected data on adverse drug reactions (ADRs), serious ADRs (SADRs) and ADRs of special interest (ADRSI) at baseline and then every 3 months. Post hoc stepwise logistic regression models were used to identify baseline characteristics associated with discontinuing treatment due to an ADR. Patients (n=1009, 99.7% with idiopathic pulmonary fibrosis) had a median pirfenidone exposure of 442.0 days. Overall, 741 (73.4%) patients experienced ADRs, most commonly nausea (20.6%) and fatigue (18.5%). ADRs led to treatment discontinuation in 290 (28.7%) patients after a median of 99.5 days. Overall, 55 (5.5%) patients experienced SADRs, with a fatal outcome in six patients. ADRSI were reported in 693 patients, most commonly gastrointestinal symptoms (38.3%) and photosensitivity reactions/skin rashes (29.0%). Older age and female sex were associated with early treatment discontinuation due to an ADR. Findings were consistent with the known safety profile of pirfenidone, based on RCT data and other post-marketing experience, with no new safety signals observed