Adattamento e acclimatazione a diverse temperature di lieviti psicrofili obbligati e facoltativi e di lieviti mesofili. Studio della produzione di acidi grassi polinsaturi omega-3 e omega-6 per via fermentativa.

Adaptation and acclimation to different temperatures of obligate psychrophilic, facultative psychrophilic and mesophilic yeasts. Production of ω-3 and ω-6 polyunsaturated fatty acids by fermentative way. Obligate psychrophilic, facultative psychrophilic and mesophilic yeasts were cultured in a carbon rich medium at different temperatures to investigate if growth parameters, lipid accumulation and fatty acid composition were adaptive and/or acclimatory responses. Acclimation of facultative psychrophiles and mesophiles to lower temperature negatively affected their specific growth rate. Obligate psychrophiles exhibited the highest biomass yield (YX/S), followed by facultative psychrophiles, then by mesophiles. The growth temperature did not influence the YX/S of facultative psychrophiles and mesophiles. Acclimation to lower temperature caused the increase in lipid yield (YL/X) in mesophilic yeasts, but did not affect YL/X in facultative psychrophiles. Similar YL/X were found in both facultative and obligated psychrophiles, suggesting that lipid accumulation is not a distinctive character of adaptation to permanently cold environments. The extent of unsaturation of fatty acids was one major adaptive feature of the yeasts which colonize permanently cold ecosystems. Remarkable amounts of α-linolenic acid were found in obligate psychrophiles at the expenses of linoleic acid, whereas it was generally scarce or absent in all the others strains. Increased unsaturation of fatty acids was also an acclimatory response of mesophiles and facultative psychrophiles to lower temperature. It’s well known that omega-3 polyunsaturated fatty acids (PUFAs) display a variety of beneficial effects on various organ systems and diseases, therefore a process for the microbial production of omega-3 PUFAs would be of great interest. This work sought also to investigate if one of the better psychrophilic yeast, Rhodotorula glacialis DBVPG 4785, stimulated by acclamatory responses, produced omega-3 PUFAs. In fact, the adaptation of psychrophilic yeasts to cold niches is related to the production of higher amounts of lipids and to increased unsaturation degree of fatty acids, presumably to maintain membrane fluidity and functionality at low temperatures. Bioreactor fermentations of Rhodotorula glacialis DBVPG 4785 were carried out at 25, 20, 15, 10, 5, 0, and -3°C in a complex medium with high C:N ratio for 15 days. High biomass production was attained at all the temperatures with a similar biomass/glucose yield (YXS), between 0.40 and 0.45, but the specific growth rate of the strain decreased as the temperature diminished. The coefficients YL/X have been measured between a minimum of 0.50 to a maximum of 0.67, but it was not possible to show a clear effect of temperature. Similarly, the coefficient YL/S ranges from a minimum of 0.22 to a maximum of 0.28: again, it does not appear to be any significant changes due to temperature. Among omega-3 PUFAs, only α-linolenic acid (ALA, 18:3n-3) was found at temperatures below to 0°C, while, it’s remarkable, that the worthy arachidonic acid (C20:4,n-6), stearidonic acid (C20:4,n-3) C22:0 and docosahexaenoic acid (C22:6n-3) were produced only at the late exponential phase and the stationary phase of batch fermentations at 0 and -3°C. The docosahexaenoic acid (DHA) is a beneficial omega-3 PUFA that is usually found in fatty fish and fish oils. The results herein reported improve the knowledge about the responses which enable psychrophilic yeasts to cope with cold and may support exploitation of these strains as a new resource for biotechnological applications.

Outcome respiratorio a lungo termine nei soggetti affetti da cardiopatia congenita sottoposti ad intervento cardiochirurgico

Introduction: In the last years cardiac surgery for congenital heart disease (CHD) reduced dramatically mortality modifying prognosis, but, at the same time, increased morbidity in this patient population. Respiratory and cardiovascular systems are strictly anatomically and functionally connected, so that alterations of pulmonary hemodynamic conditions modify respiratory function. While very short-term alterations of respiratory mechanics after surgery were investigated by many authors, not as much works focused on long-term changes. In these subjects rest respiratory function may be limited by several factor: CHD itself (fetal pulmonary perfusion influences vascular and alveolar development), extracorporeal circulation (CEC), thoracotomy and/or sternotomy, rib and sternal contusions, pleural adhesions and pleural fibrosis, secondary to surgical injury. Moreover inflammatory cascade, triggered by CEC, can cause endothelial damage and compromise gas exchange. Aims: The project was conceived to 1) determine severity of respiratory functional impairement in different CHD undergone to surgical correction/palliation; 2) identify the most and the least CHD involved by pulmonary impairement; 3) find a correlation between a specific hemodynamic condition and functional anomaly, and 4) between rest respiratory function and cardiopulmonary exercise test. Materials and methods: We studied 113 subjects with CHD undergone to surgery, and distinguished by group in accord to pulmonary blood flow (group 0: 28 pts with normal pulmonary flow; group 1: 22 pts with increased flow; group 2: 43 pts with decreased flow; group 3: 20 pts with total cavo-pulmonary anastomosis-TCPC) followed by the Pediatric Cardiology and Cardiac Surgery Unit, and we compare them to 37 age- and sex-matched healthy subjects. In Pediatric Pulmonology Unit all pts performed respiratory function tests (static and dynamic volumes, flow/volume curve, airway resistances-raw- and conductance-gaw-, lung diffusion of CO-DLCO- and DLCO/alveolar volume), and CHD pts the same day had cardiopulmonary test. They all were examined and had allergological tests, and respiratory medical history. Results: restrictive pattern (measured on total lung capacity-TLC- and vital capacity-VC) was in all CHD groups, and up to 45% in group 2 and 3. Comparing all groups, we found a significant difference in TLC between healthy and group 2 (p=0.001) and 3 (p=0.004), and in VC between group 2 and healthy (p=0.001) and group 1(p=0.034). Inspiratory capacity (IC) was decreased in group 2 related to healthy (p<0.001) and group 1 (p=0.037). We showed a direct correlation between TLC and VC with age at surgery (p=0.01) and inverse with number of surgical interventions (p=0.03). Reduced FEV1/FVC ratio, Gaw and increased Raw were mostly present in group 3. DLCO was impaired in all groups, but up to 80% in group 3 and 50% in group 2; when corrected for alveolar volume (DLCO/VA) reduction persisted in group 3 (20%), 2 (6.2%) and 0 (7.1%). Exercise test was impaired in all groups: VO2max and VE markedly reduced in all but especially in group 3, and VE/VCO2 slope, marker of ventilatory response to exercise, is increased (<36) in 62.5% of group 3, where other pts had anyway value>32. Comparing group 3 and 2, the most involved categories, we found difference in VO2max and VE/VCO2 slope (respectively p=0.02 and p<0.0001). We evidenced correlation between rest and exercise tests, especially in group 0 (between VO2max and FVC, FEV1, VC, IC; inverse relation between VE/VCO2slope and FVC, FEV1 and VC), but also in group 1 (VO2max and IC), group 2 (VO2max and FVC and FEV1); never in group 3. Discussion: According with literature, we found a frequent impairment of rest pulmonary function in all groups, but especially in group 2 and 3. Restrictive pattern was the most frequent alteration probably due to compromised pulmonary (vascular and alveolar) development secondary to hypoperfusion in fetal and pre-surgery (and pre-TCPC)life. Parenchymal fibrosis, pleural adhesions and thoracic deformities can add further limitation, as showed by the correlation between group 3 and number of surgical intervention. Exercise tests were limited, particularly in group 3 (complex anatomy and lost of chronotropic response), and we found correlations between rest and exercise tests in all but group 3. We speculate that in this patients hemodynamic exceeds respiratory contribution, though markedly decreased.

Excitonic processes in multifunctional organic semiconductors for application in organic-light emitting transistor

In this thesis, I report on a comprehensive study about the photo-physical properties both in solution and in solid-state of a new thiophene based material (2,2’-(2,2’-bithiophene-5,5’-diyl)bis(5-butyl-5H-thieno[2,3-c]pyrrole-4,6)-dione (T4DIM) which shows an ambipolar semiconducting behavior together with electroluminescence in single-layer OLET device architecture[14