Corticolimbic catecholamines in stress: A computational model of the appraisal of controllability

Appraisal of a stressful situation and the possibility to control or avoid it is thought to involve frontal-cortical mechanisms. The precise mechanism underlying this appraisal and its translation into effective stress coping (the regulation of physiological and behavioural responses) are poorly understood. Here, we propose a computational model which involves tuning motivational arousal to the appraised stressing condition. The model provides a causal explanation of the shift from active to passive coping strategies, i.e. from a condition characterised by high motivational arousal, required to deal with a situation appraised as stressful, to a condition characterised by emotional and motivational withdrawal, required when the stressful situation is appraised as uncontrollable/unavoidable. The model is motivated by results acquired via microdialysis recordings in rats and highlights the presence of two competing circuits dominated by different areas of the ventromedial prefrontal cortex: these are shown having opposite effects on several subcortical areas, affecting dopamine outflow in the striatum, and therefore controlling motivation. We start by reviewing published data supporting structure and functioning of the neural model and present the computational model itself with its essential neural mechanisms. Finally, we show the results of a new experiment, involving the condition of repeated inescapable stress, which validate most of the model's prediction

The role of cross-over bypass graft in the treatment of acute ischaemia of the lower limb

Introduction. The Authors reports their experience with the use of femoro-femoral cross-over bypass graft in the management of acute lower limb ischaemia. Patients and methods. Fourteen femoro-femoral bypass graft were performed for acute lower limb ischaemia due to unilateral thrombosis of iliac and femoral artery in 8 cases, late unilateral occlusion of a branch of previous aortobifemoral bypass in 3 cases, acute thrombosis of abdominal aorta in 2 cases and in the last one for an injury of common iliac artery during urological procedure. In all the cases the operations were carried out under local anaesthesia and a subcutaneous bypass with “C” shape type configuration with 8 mm Dacron prosthesis were performed. The first and second year primary and secondary patency rates and limb salvage rates were evaluated. Results. One and two year patency rate was 83.3 (10/12) and 70% (7/10) respectively. Secondary patency rate and limb salvage rate was 91.6% (11/12) and 80% (8/10) respectively. A tight amputation had to performed in 3 failed reconstruction (3/12, 25%). Two patient died within 30 days after surgery from acute myocardial infarct. In 1 case infection occurred and re-do femorofemoral cross-over bypass with saphenous vein was carried out (8.3%). Conclusions. Cross-over bypass is an attractive technique, especially in case of acute ischemia because of its simplicity, low morbidity and mortality, and good long term results

Axial Thrust in High Pressure Centrifugal Compressors: Description of a Calculation Model Validated by Experimental Data from Full Load Test

LectureThe residual axial thrust acting on the rotor of a centrifugal compressor is the result of the non-uniform pressure distribution on the surfaces in contact with the process gas, plus the differential pressure acting on the faces of the balance piston(s) and the contribution due to the momentum variation of the process gas. During the design phase the axial load shall be verified to remain safely lower than the thrust bearing capacity, under all possible operating conditions; this requires a high degree of accuracy in the calculation model used to evaluate each thrust component. Errors in this calculation may lead to high bearing pad temperature during operation, to early wearing of the pad surfaces and ultimately to the damage or failure of the thrust bearing (Moll and Postill, 2011), thus jeopardizing the integrity of the whole compressor. The main difficulty of axial thrust calculation lies in the correct prediction of the static pressure distribution over the external surface of the impeller hub and shroud. This distribution depends on a large set of parameters, including rotor geometry, operating conditions, properties of the process gas, leakages flows across the rotor-stator seals. A detailed fluid-dynamic model of the gas in the cavities between impeller and diaphragm was developed and applied first to stage model tests and then to high-pressure centrifugal compressors, and its predictability was assessed by direct comparison with experimental data. The compressors were tested in full load conditions, with thrust bearing pads equipped with load cells, and the thrust values were recorded for several points across the operating envelope

Corticolimbic catecholamines in stress: a computational model of the appraisal of controllability

Appraisal of a stressful situation and the possibility to control or avoid it is thought to involve frontal-cortical mechanisms. The precise mechanism underlying this appraisal and its translation into effective stress coping (the regulation of physiological and behavioural responses) are poorly understood. Here, we propose a computational model which involves tuning motivational arousal to the appraised stressing condition. The model provides a causal explanation of the shift from active to passive coping strategies, i.e. from a condition characterised by high motivational arousal, required to deal with a situation appraised as stressful, to a condition characterised by emotional and motivational withdrawal, required when the stressful situation is appraised as uncontrollable/unavoidable. The model is motivated by results acquired via microdialysis recordings in rats and highlights the presence of two competing circuits dominated by different areas of the ventromedial prefrontal cortex: these are shown having opposite effects on several subcortical areas, affecting dopamine outflow in the striatum, and therefore controlling motivation. We start by reviewing published data supporting structure and functioning of the neural model and present the computational model itself with its essential neural mechanisms. Finally, we show the results of a new experiment, involving the condition of repeated inescapable stress, which validate most of the model\u27s predictions

Honeycomb Seal Effect on Rotor Response to Unbalance

LectureHigh pressure centrifugal compressors are often equipped with honeycomb seal on balance drum in order to optimize rotordynamic stability. In very high pressures applications (>200 bar) the direct stiffness and damping of the honeycomb seal may reach the same order of magnitude of the journal bearings, thus altering the peak frequency and amplification factor of rotor critical speeds as well as their mode shapes. This phenomenon is ultimately due to the density and viscosity of the gas leakage flowing through the seal, and it has a substantial effect on the rotordynamic behavior of the compressor. According to current standards, aerodynamic seal effects are not necessarily included in the calculation of rotor response to unbalance. For high pressure compressors equipped with a honeycomb seal, the associated aerodynamic effects may have major impacts on rotor critical speeds in terms of frequency, amplitude and amplification factor. A procedure for the calculation of rotor response in loaded condition is here proposed, aiming to improve the predictability of the rotordynamic analysis and to provide practical criteria for the evaluation of the outcome. A back-to-back compressor with final discharge pressure of 386 bar is presented as case study; it was tested at full pressure at Authors’ Company facilities in 2013. In this case the stiffening effect of the honeycomb seal is particularly relevant, since it is positioned close to rotor midspan. Test measures show that in loaded condition the 1st critical speed shifts upwards by several thousand rpm, eventually exceeding the Maximum Critical Speed and even the Trip Speed of the compressor

Effect of short-term aerobic exercise on cardiovascular remodelling in post-menopause women

It is well known that menopause is associated with an increase of cardiovascular (CV) risk factors, including changes on metabolic profile, body composition, haemdynamic loads and cardiovascular remodelling. The latter starts with an increase of arterial elastance and early concentric left ventricular remodeling, manifested by an increment of the relative wall thickness. We investigated morphological and functional effects of short-term aerobic exercise at moderate intensity without diet restriction on cardiovascular apparatus in post-menopause women. Seventy-six post-menopausal healthy sedentary postwomen (56± 4 yrs) underwent clinical history, physician and anthropometric exam, 12-lead electrocardiography. Echocardiography was used to assess LV geometry and systolic and diastolic functions. Relative diastolic wall thickness (RWT), midwall fractional shortening (MFS) and arterial elastance (AE) were calculated to evaluate the LV concentric remodeling, the intrinsic systolic function and the vascular load, respectively. Data were collected before and after 14 weeks of moderate aerobic exercise training (four time per week). After the intervention program, systolic and diastolic arterial pressure, heart rate and hip circumference were significantly decreased (P = 0,01; P = 0,00; P = 0,00; P = 0,01, respectively). Left ventricular mass/height 2.7, ejection fraction and MFS were higher (p< 0,00; P= 0,00; P =0,00), while relative wall thickness (RWT) and AE were lower (P<0,03;P=0,00). Mitral E wave and E/A were higher (P = 0,001; P<0,0001). Left ventricular mass/height 2.7 was correlated to BMI (P = 0,04), WC (P = 0,034) and waist/hip ratio (P = 0,007). In post-menopause women aerobic exercise improves CV function (concentric remodelling, diastolic and systolic function) acting both on haemodynamic factors and body composition. Our data underline the role of non pharmacological interventions in the CV disease prevention

Refinement of the diagnostic approach for the identification of children and adolescents affected by familial hypercholesterolemia: Evidence from the LIPIGEN study

Background and aims: We aimed to describe the limitations of familiar hypercholesterolemia (FH) diagnosis in childhood based on the presence of the typical features of FH, such as physical sings of cholesterol accumulation and personal or family history of premature cardiovascular disease or hypercholesterolemia, comparing their prevalence in the adult and paediatric FH population, and to illustrate how additional information can lead to a more effective diagnosis of FH at a younger age.Methods: From the Italian LIPIGEN cohort, we selected 1188 (>= 18 years) and 708 (<18 years) genetically-confirmed heterozygous FH, with no missing personal FH features. The prevalence of personal and familial FH features was compared between the two groups. For a sub-group of the paediatric cohort (N = 374), data about premature coronary heart disease (CHD) in second-degree family members were also included in the evaluation.Results: The lower prevalence of typical FH features in children/adolescents vs adults was confirmed: the prevalence of tendon xanthoma was 2.1% vs 13.1%, and arcus cornealis was present in 1.6% vs 11.2% of the cohorts, respectively. No children presented clinical history of premature CHD or cerebral/peripheral vascular disease compared to 8.8% and 5.6% of adults, respectively. The prevalence of premature CHD in first-degree relatives was significantly higher in adults compared to children/adolescents (38.9% vs 19.7%). In the sub-cohort analysis, a premature CHD event in parents was reported in 63 out of 374 subjects (16.8%), but the percentage increased to 54.0% extending the evaluation also to second-degree relatives.Conclusions: In children, the typical FH features are clearly less informative than in adults. A more thorough data collection, adding information about second-degree relatives, could improve the diagnosis of FH at younger age

Clinical features and outcomes of elderly hospitalised patients with chronic obstructive pulmonary disease, heart failure or both

Background and objective: Chronic obstructive pulmonary disease (COPD) and heart failure (HF) mutually increase the risk of being present in the same patient, especially if older. Whether or not this coexistence may be associated with a worse prognosis is debated. Therefore, employing data derived from the REPOSI register, we evaluated the clinical features and outcomes in a population of elderly patients admitted to internal medicine wards and having COPD, HF or COPD + HF. Methods: We measured socio-demographic and anthropometric characteristics, severity and prevalence of comorbidities, clinical and laboratory features during hospitalization, mood disorders, functional independence, drug prescriptions and discharge destination. The primary study outcome was the risk of death. Results: We considered 2,343 elderly hospitalized patients (median age 81 years), of whom 1,154 (49%) had COPD, 813 (35%) HF, and 376 (16%) COPD + HF. Patients with COPD + HF had different characteristics than those with COPD or HF, such as a higher prevalence of previous hospitalizations, comorbidities (especially chronic kidney disease), higher respiratory rate at admission and number of prescribed drugs. Patients with COPD + HF (hazard ratio HR 1.74, 95% confidence intervals CI 1.16-2.61) and patients with dementia (HR 1.75, 95% CI 1.06-2.90) had a higher risk of death at one year. The Kaplan-Meier curves showed a higher mortality risk in the group of patients with COPD + HF for all causes (p = 0.010), respiratory causes (p = 0.006), cardiovascular causes (p = 0.046) and respiratory plus cardiovascular causes (p = 0.009). Conclusion: In this real-life cohort of hospitalized elderly patients, the coexistence of COPD and HF significantly worsened prognosis at one year. This finding may help to better define the care needs of this population

The “Diabetes Comorbidome”: A Different Way for Health Professionals to Approach the Comorbidity Burden of Diabetes

(1) Background: The disease burden related to diabetes is increasing greatly, particularly in older subjects. A more comprehensive approach towards the assessment and management of diabetes’ comorbidities is necessary. The aim of this study was to implement our previous data identifying and representing the prevalence of the comorbidities, their association with mortality, and the strength of their relationship in hospitalized elderly patients with diabetes, developing, at the same time, a new graphic representation model of the comorbidome called “Diabetes Comorbidome”. (2) Methods: Data were collected from the RePoSi register. Comorbidities, socio-demographic data, severity and comorbidity indexes (Cumulative Illness rating Scale CIRS-SI and CIRS-CI), and functional status (Barthel Index), were recorded. Mortality rates were assessed in hospital and 3 and 12 months after discharge. (3) Results: Of the 4714 hospitalized elderly patients, 1378 had diabetes. The comorbidities distribution showed that arterial hypertension (57.1%), ischemic heart disease (31.4%), chronic renal failure (28.8%), atrial fibrillation (25.6%), and COPD (22.7%), were the more frequent in subjects with diabetes. The graphic comorbidome showed that the strongest predictors of death at in hospital and at the 3-month follow-up were dementia and cancer. At the 1-year follow-up, cancer was the first comorbidity independently associated with mortality. (4) Conclusions: The “Diabetes Comorbidome” represents the perfect instrument for determining the prevalence of comorbidities and the strength of their relationship with risk of death, as well as the need for an effective treatment for improving clinical outcomes

Antidiabetic Drug Prescription Pattern in Hospitalized Older Patients with Diabetes

Objective: To describe the prescription pattern of antidiabetic and cardiovascular drugs in a cohort of hospitalized older patients with diabetes. Methods: Patients with diabetes aged 65 years or older hospitalized in internal medicine and/or geriatric wards throughout Italy and enrolled in the REPOSI (REgistro POliterapuie SIMI—Società Italiana di Medicina Interna) registry from 2010 to 2019 and discharged alive were included. Results: Among 1703 patients with diabetes, 1433 (84.2%) were on treatment with at least one antidiabetic drug at hospital admission, mainly prescribed as monotherapy with insulin (28.3%) or metformin (19.2%). The proportion of treated patients decreased at discharge (N = 1309, 76.9%), with a significant reduction over time. Among those prescribed, the proportion of those with insulin alone increased over time (p = 0.0066), while the proportion of those prescribed sulfonylureas decreased (p < 0.0001). Among patients receiving antidiabetic therapy at discharge, 1063 (81.2%) were also prescribed cardiovascular drugs, mainly with an antihypertensive drug alone or in combination (N = 777, 73.1%). Conclusion: The management of older patients with diabetes in a hospital setting is often sub-optimal, as shown by the increasing trend in insulin at discharge, even if an overall improvement has been highlighted by the prevalent decrease in sulfonylureas prescription