Equilibrium unfolding of the PDZ domain of β2-syntrophin

b2-syntrophin, a dystrophin-associated protein, plays a pivotal role in insulin secretion by pancreatic b-cells. Itcontains a PDZ domain (b2S-PDZ) that, in complex with protein-tyrosine phosphatase ICA512, anchors the dense insulin gran-ules to actin filaments. The phosphorylation state of b2-syntrophin allosterically regulates the affinity of b2S-PDZ for ICA512,and the disruption of the complex triggers the mobilization of the insulin granule stores. Here, we investigate the thermal unfold-ing of b2S-PDZ at different pH and urea concentrations. Our results indicate that, unlike other PDZ domains, b2S-PDZ is margin-ally stable. Thermal denaturation experiments show broad transitions and cold denaturation, and a two-state model fit revealsa significant unfolded fraction under physiological conditions. Furthermore, Tm and Tmax denaturant-dependent shifts andnoncoincidence of melting curves monitored at different wavelengths suggest that two-state and three-state models fail toexplain the equilibrium data properly and are in better agreement with a downhill scenario. Its higher stability at pH >9 andthe results of molecular dynamics simulations indicate that this behavior of b2S-PDZ might be related to its charge distribution.All together, our results suggest a link between the conformational plasticity of the native ensemble of this PDZ domain and theregulation of insulin secretion.Fil: Torchio, Gabriela María. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Expresion y Plegamiento de Proteinas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ermacora, Mario Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Expresion y Plegamiento de Proteinas; ArgentinaFil: Sica, Mauricio Pablo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Expresion y Plegamiento de Proteinas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Equilibrium unfolding of the PDZ domain of β2-syntrophin

β2-syntrophin, a dystrophin-associated protein, plays a pivotal role in insulin secretion by pancreatic β-cells. It contains a PDZ domain (β2S-PDZ) that, in complex with protein-tyrosine phosphatase ICA512, anchors the dense insulin granules to actin filaments. The phosphorylation state of β2-syntrophin allosterically regulates the affinity of β2S-PDZ for ICA512, and the disruption of the complex triggers the mobilization of the insulin granule stores. Here, we investigate the thermal unfolding of β2S-PDZ at different pH and urea concentrations. Our results indicate that, unlike other PDZ domains, β2S-PDZ is marginally stable. Thermal denaturation experiments show broad transitions and cold denaturation, and a two-state model fit reveals a significant unfolded fraction under physiological conditions. Furthermore, Tm and Tmax denaturant-dependent shifts and noncoincidence of melting curves monitored at different wavelengths suggest that two-state and three-state models fail to explain the equilibrium data properly and are in better agreement with a downhill scenario. Its higher stability at pH > 9 and the results of molecular dynamics simulations indicate that this behavior of β2S-PDZ might be related to its charge distribution. All together, our results suggest a link between the conformational plasticity of the native ensemble of this PDZ domain and the regulation of insulin secretion.Instituto Multidisciplinario de Biología Celula

Minute ventilation to carbon dioxide output (V’E/V’CO2 slope) is the strongest death predictor before larger lung resections

The minute ventilation to CO2 production ratio (V’E/V’CO2 slope) was recently identified as a mortality predictor after lung surgery, but the effect of the resection extent was not taken into account.  The aim of this study was to investigate the role of V’E/V’CO2 slope as preoperative mortality predictor depending on the type of surgery performed. Retrospective analysis was performed on 263 consecutive patients evaluated before surgery for lung cancer. Death within 30 days and serious respiratory complications were considered. Univariate and multivariate regression analyses were used to identify independent predictors of death. Lobectomy or bilobectomy were performed in 186 patients with 29/186 (15.6%) serious pulmonary complications and 6/186 (3.2%) deaths. Pneumonectomy was performed in 77 patients with 14/77 (18.2%) serious complications and 5/77 (6.5%) deaths.  Considering the whole group, the peak oxygen consumption (V'02peak, L/ min; z=-2.66, p<0.008, OR 0.007) and V'E/V'C02 slope (z=2.80, p<0.005, OR 1.14) were independent predictors of mortality whereas in pneumonectomies V'E/V'C02 slope (z=2.34, p<0.02, OR 1.22) was the only independent predictor of mortality. High V’E/V’CO2 slope, age and low V'02peak are predictors of death and severe complications after lung surgery. Before larger resections as pneumonectomies an increased V’E/V’CO2 slope represents the best mortality predictor

Predictors of cardiovascular disease in asthma and chronic obstructive pulmonary disease

BACKGROUND: Cardiovascular disease (CVD) is a common comorbidity in patients with chronic airway obstruction, and is associated with systemic inflammation and airway obstruction. The aim of this study was to evaluate the predictors of CVD in two different conditions causing chronic airway obstruction, asthma and COPD. METHODS: Lung function tests, clinical and echocardiographic data were assessed in 229 consecutive patients, 100 with asthma and 129 with COPD. CVD was classified into: pressure overload (PO) and volume overload (VO). Sub-analysis of patients with ischemic heart disease (IHD) and pulmonary hypertension (PH) was also performed. RESULTS: CVD was found in 185 patients (81%: 51% COPD and 30% asthmatics) and consisted of PO in 42% and of VO in 38% patients. COPD patients, as compared to asthmatics, had older age, more severe airway obstruction, higher prevalence of males, of smokers, and of CVD (91% vs 68%), either PO (46% vs 38%) or VO (45% vs 30%). CVD was associated with older age and more severe airway obstruction both in asthma and COPD. In the overall patients the predictive factors of CVD were age, COPD, and male sex; those of PO were COPD, BMI, VC, FEV(1) and MEF(50) and those of VO were age, VC and MEF(50). In asthma, the predictors of CVD were VC, FEV(1), FEV(1) /VC%, and PaO(2), those of PO were VC, FEV(1) and FEV(1) /VC%, while for VO there was no predictor. In COPD the predictors of CVD were age, GOLD class and sex, those of VO age, VC and MEF(50), and that of PO was BMI. Sub-analysis showed that IHD was predicted by COPD, age, BMI and FEV(1), while PH (found only in 25 COPD patients), was predicted by VO (present in 80% of the patients) and FEV(1). In subjects aged 65 years or more the prevalence of CVD, PO and VO was similar in asthmatic and COPD patients, but COPD patients had higher prevalence of males, smokers, IHD, PH, lower FEV(1) and higher CRP. CONCLUSIONS: The results of this study indicate that cardiovascular diseases are frequent in patients with chronic obstructive disorders, particularly in COPD patients. The strongest predictors of CVD are age and airway obstruction. COPD patients have higher prevalence of ischemic heart disease and pulmonary hypertension. In the elderly the prevalence of PO and VO in asthma and COPD patients is similar

Equilibrium unfolding of the PDZ domain of β2-syntrophin

β2-syntrophin, a dystrophin-associated protein, plays a pivotal role in insulin secretion by pancreatic β-cells. It contains a PDZ domain (β2S-PDZ) that, in complex with protein-tyrosine phosphatase ICA512, anchors the dense insulin granules to actin filaments. The phosphorylation state of β2-syntrophin allosterically regulates the affinity of β2S-PDZ for ICA512, and the disruption of the complex triggers the mobilization of the insulin granule stores. Here, we investigate the thermal unfolding of β2S-PDZ at different pH and urea concentrations. Our results indicate that, unlike other PDZ domains, β2S-PDZ is marginally stable. Thermal denaturation experiments show broad transitions and cold denaturation, and a two-state model fit reveals a significant unfolded fraction under physiological conditions. Furthermore, Tm and Tmax denaturant-dependent shifts and noncoincidence of melting curves monitored at different wavelengths suggest that two-state and three-state models fail to explain the equilibrium data properly and are in better agreement with a downhill scenario. Its higher stability at pH > 9 and the results of molecular dynamics simulations indicate that this behavior of β2S-PDZ might be related to its charge distribution. All together, our results suggest a link between the conformational plasticity of the native ensemble of this PDZ domain and the regulation of insulin secretion.Instituto Multidisciplinario de Biología Celula

Ventricular pacemaker lead in the left hemithorax: Mechanisms and evidence-based management of a late-onset hazardous complication

Late-onset migration of pacing leads in the left hemithorax is a rare but potentially life-threatening complication. Radiological examinations are required to detect any involvement of either left ventricle or lung parenchyma, prompting immediate surgical extraction in this setting. Identification of high-risk patients is mandatory to prevent this complex iatrogenic complication

Integrating the care of the complex COPD patient

The European Seminars in Respiratory Medicine has represented an outstanding series updating new science in respiratory disease from the 1990\u2019s up to the early beginning of this 21st century [1,2]. Its aim is to update issues and current science, focusing on the multidisciplinary approach to patients with respiratory disease. As such, it represents a unique opportunity for specialists in Respiratory Medicine involved in Basic and Clinical Research to discuss topical and debated problems in medical care, at a top level forum guided by an expert panel of authors. The structure of the seminar is based on the following pillars: \u2022 Attendance at the Seminars is strictly limited: selection of participants is based, in order of priority, on scientific curriculum, age (younger specialists are privileged), and early receipt of the application form. \u2022 Each topic is allotted considerable time for presentation and discussion. The first section is devoted to a series of presentations (with adequate time allocated for discussion) by an expert panel of researchers and clinicians. In the second section involves discussions of controversial issues, in a smaller audience format encouraging interaction between the panel and audience. \u2022 \u201cMeet the expert\u201d seminars discuss topical subjects in more depth, utilizing an interactive tutorial

Inhalation therapy in the next decade : Determinants of adherence to treatment in asthma and COPD

Peer reviewedPublisher PD

Association of kidney disease measures with risk of renal function worsening in patients with type 1 diabetes

Background: Albuminuria has been classically considered a marker of kidney damage progression in diabetic patients and it is routinely assessed to monitor kidney function. However, the role of a mild GFR reduction on the development of stage 653 CKD has been less explored in type 1 diabetes mellitus (T1DM) patients. Aim of the present study was to evaluate the prognostic role of kidney disease measures, namely albuminuria and reduced GFR, on the development of stage 653 CKD in a large cohort of patients affected by T1DM. Methods: A total of 4284 patients affected by T1DM followed-up at 76 diabetes centers participating to the Italian Association of Clinical Diabetologists (Associazione Medici Diabetologi, AMD) initiative constitutes the study population. Urinary albumin excretion (ACR) and estimated GFR (eGFR) were retrieved and analyzed. The incidence of stage 653 CKD (eGFR &lt; 60 mL/min/1.73 m2) or eGFR reduction &gt; 30% from baseline was evaluated. Results: The mean estimated GFR was 98 \ub1 17 mL/min/1.73m2 and the proportion of patients with albuminuria was 15.3% (n = 654) at baseline. About 8% (n = 337) of patients developed one of the two renal endpoints during the 4-year follow-up period. Age, albuminuria (micro or macro) and baseline eGFR &lt; 90 ml/min/m2 were independent risk factors for stage 653 CKD and renal function worsening. When compared to patients with eGFR &gt; 90 ml/min/1.73m2 and normoalbuminuria, those with albuminuria at baseline had a 1.69 greater risk of reaching stage 3 CKD, while patients with mild eGFR reduction (i.e. eGFR between 90 and 60 mL/min/1.73 m2) show a 3.81 greater risk that rose to 8.24 for those patients with albuminuria and mild eGFR reduction at baseline. Conclusions: Albuminuria and eGFR reduction represent independent risk factors for incident stage 653 CKD in T1DM patients. The simultaneous occurrence of reduced eGFR and albuminuria have a synergistic effect on renal function worsening