Ecophysiology of Ruditapes decussatus

The physiological responses of the clam R. decussatus from the Ria Formosa, southern Portugal, were examined in relation to normoxia, hypoxia (11, 6, 3 and 1.2 kPa) and anoxia; acute elevation of temperature (at 20, 27 and 32 ��C), and its effect on the resistance to air exposure (at 20, 28 and 35 ��C); current velocity (0.6, 3, 8 17, 24 and 36 cm. s-1) and turbidity (10, 100 and 300 mg. l-1 dry weight of particulate matter), and the efficiency of this species in retaining particles of different size (at 10 and 100 mg. l-1); and to copper contamination considering both short-term acute exposure to high levels (0.1-10 mg Cu. l-1) and chronic environmental levels (0.01 mg Cu. l-1). Clearance rates, respiration rates, absorption efficiency and excretion rates were assessed through the physiological energetics in terms of the energy budget and scope for growth (SFG). Stress independent respiration rates (R) and clearance rates (CR) were observed in relation to hypoxia down to 12 kPa and 6 kPa, respectively. Anoxic rates were 3.6 % of normoxic rates. Scope for growth was greatly reduced under extreme hypoxia (14 % of SFG in normoxia). Respiration rate was temperature independent in the range 20-32 ��C but the decline in clearance rate resulted in negative SFG at 32 ��C. Gaping during air exposure and the maintenance of faster aerobic metabolism led to 100 % mortality in 20 hours at 35 ��C, 4 days at 28 ��C and 5 days at 20 ��C. Low current velocities (��� 8 cm. s-1) supported high clearance rates. Shear stresses ��� 0.9 Pa induced sediment movement and disturbed the feeding processes resulting in decreased clearance rates (at 36 cm. s-1, is 10 % of maximum CR). The observed ability of jetting out depleted water at a different level than the one of the inhalant current results is an important adaptation of clams to the slow currents of sheltered environments. Ingestion at high seston concentrations (> 100 mg. l-1) is controled by reducing the amount filtered, lowering CR (to 30 % of CR at low seston loads) and producing pseudofeces. Observed efficient retention of particles (70-100 %) in the range 3 to 8 ��m is beneficial when algal cells are diluted by fine silt particles as it is likely to occur in the clams natural environment. R. decussatus in the short term escaped the exposure to copper by valve closure and therefore acute tests are not applicable to adult clams of this species. At environmental levels chronic exposure to copper did not induce lethal effects during the exposure period (20 days), but scope for growth was reduced to c. 30 %, indicating sustained impairment of physiological functions. The sensitivity of the physiological energetics and the integrated scope for growth measurement in assessing stress effects caused by natural environmental factors was highlighted.

Towards cryogenic liquid ���vapor energy storage units for space applications

Dissertation to obtain the Doctoral degree in Physics Engineering

Validation of alternative additives for paste production

Dissertation presented to confer Master Degree in Chemical and Biochemical Engineering

Atherogenesis and atherosclerosis in primary antiphospholipid syndrome

ABSTRACT: In the late seventies the term ���Haematological Stress Syndrome��� defined some haematological abnormalities appearing in the course of acute and chronic disorders, such as raised plasma levels of fibrinogen (FNG) and factor VIII, reduced fibrinolytic activity and hyperviscosity. In the early nineties the ���Membrane stress syndrome hypothesis��� proposed the unification of the concepts of haematological stress syndrome with those of oxidation, inflammation and immune activation to explain the pathogenesis of the antiphospholipid syndrome (APS) Antiphospholipid antibodies, coagulation, fibrinolysis and thrombosis. This chapter investigated the occurrence of the ���Haematological Stress Syndrome��� and thrombosis in 144 participants positive for aPL detected by clotting and immune tests. Among the clotting assays for the detection of lupus anticoagulant, dilute Russell's viper venom time better correlated with a history of venous thrombosis than activated partial thromboplastin time (p<0.0002 vs p<0.009) and was the only test correlated with a history of arterial thrombosis (p<0.01). By regression analysis, serum levels of IgG anticardiolipin antibodies (aCL) associated with the number of venous occlusions (p<0.001). With regards to FNG and von Willebrand factor (vWF), the former rose by 36% (95% CI; 21%, 53%) and the latter by 50% (95% CI; 29%, 75%) at the first venous occlusion and remained unchanged after subsequent occlusions. At variance FNG rose by 45% (95% CI; 31%, 60%) per arterial occlusion and vWF by 27% (95% CI; 10%, 47%) per arterial occlusion throughout. The coagulation/fibrinolytic balance was cross-sectionally evaluated on 18 thrombotic PAPS patients, 18 subjects with persistence of idiopathic aPL and in healthy controls. Markers of thrombin generation prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complex (TAT) and of fibrin turnover D-Dimer (D-D) were higher in thrombotic (p=0.006)and non-thrombotic subjects (p=0.0001) than in controls as were those of D-D (p<0.0001 and p=0.003 respectively). TAT levels did not differ. Gender analysed data revealed blunted tPA release (hence a negative venous occlusion test) in thrombotic females but neither in thrombotic males (p=0.01) nor in asymptomatic subjects of either sex. Also, in both patient groups females had higher mean PAI than males (p<0.0002) and control females (p<0.02). The activity of factor XIII (FXIIIa) was evaluated was evaluated in 29 patients with PAPS, 14 persistent carriers of aPL without thrombosis, 24 thrombotic patients with inherited thrombophilia, 28 healthy controls and 32 patients with mitral and aortic valve prosthesis as controls for FXIII only. FXIIIa was highest in PAPS (p=0.001), particularly in patients with multiple (n=12) than single occlusion (p=0.02) and in correlation with PAI (p=0.003) and FNG (p=0.005). Moreover FXIIIa was strongly associated with IgG aCL and IgG anti-���2GPI (p=0.005 for both) in the PAPS group and to a lesser degree in the aPL group (FXIIIa with IgG aCL, p=0.02, with IgG anti-���2GPI, p=0.04). Altogether these results indicate: 1) a differential relationship of aPL, vWF and FNG with venous and arterial thrombosis; 2) heightened thrombin generation, accelerated fibrin turnover and fibrinolysis abnormalities also in asymptomatic carriers of aPLs; 3) enhanced FXIIIa that may contribute to atherothrombosis via increased fibrin/fibrinogen cross-linking. Lipid profile, lipid peroxidation and anti-lipoprotein antibodies in thrombotic primary antiphospholipid syndrome. Given the atherogenic lipid profile of SLE, the same possibility was explored in PAPS by comparing high-density lipoprotein (HDL), low-density lipoprotein (LDL), total cholesterol (CHO), apolipoprotein AI (ApoAI), apolipoprotein B (ApoB), triglycerides (TG), anti-lipoprotein antibodies, beta-2-glycoprotein I complexed to oxidized low-density lipoprotein (oxLDL-���2GPI) and C-reactive protein (CRP) in 34 thrombotic PAPS patients compared to 36 thrombotic patients with inherited thrombophilia (IT), to 18 subjects persistently positive for antiphospholipid antibodies (aPL) with no underlying autoimmune or non-autoimmune disorders and to 28 healthy controls. Average concentrations of HDL (p<0.0001), LDL (p<0.0001), CHO (p=0.0002), ApoAI (p=0.002) were lower in PAPS whereas average TRY was higher (p=0.01) than other groups. Moreover PAPS showed higher IgG anti-HDL (p=0.01) and IgG anti-ApoAI (p<0.0001) as well as greater average oxLDL-���2GPI (p=0.001) and CRP (p=0.003). Within PAPS, IgG anti-HDL correlated negatively to HDL (p=0.004) and was an independent predictor of oxLDL-���2GPI (p=0.009). HDL and ApoAI correlated negatively with CRP (p=0.001 and p=0.007, respectively). IgG anti-HDL may hamper the antioxidant and anti-inflammatory effect of HDL favouring low-grade inflammation and enhanced oxidation in thrombotic PAPS. Indeed plasma 8-epi-prostaglandin F2�� (a very specific marker of lipid peroxidation) was significantly higher in 10 patients with PAPS than 10 age and sex matched healthy subjects (p=0.0002) and strongly related to the titre of plasma IgG aCL (r=0.89, p=0.0004). Hence oxidative stress, a major player in atherogenesis, also characterises PAPS. Nitric oxide and nitrative stress in thrombotic primary antiphosholipid syndrome. Oxidative stress goes hand in hand with nitrative stress and to address the latter plasma nitrotyrosine (NT, marker of nitrative stress), nitrite (NO2-) and nitrate (NO3-) were measured in 46 thrombotic PAPS patients, 21 asymptomatic but persistent carriers of antiphospholipid antibodies (PCaPL), 38 patients with inherited thrombophilia (IT), 33 patients with systemic lupus erythematosus (SLE) and 29 healthy controls (CTR). Average crude NT was higher in PAPS and SLE (p=0.01) whereas average plasma NO2- was lower in PAPS and average NO3- highest in SLE (p<0.0001). In PAPS, IgG aCL titer and number of vascular occlusions negatively predicted NO2-, (p=0.03 and p=0.001, respectively) whereas arterial occlusions and smoking positively predicted NO3- (p=0.05 and p=0.005). Moreover CRP (an inflammatory marker) positively predicted NT (p=0.004). Nitric oxide metabolites relates to type and number of vascular occlusions and to aPL titers, whereas nitrative stress relates to low grade marker) positively predicted NT (p=0.004). Nitric oxide metabolites relates to type and number of vascular occlusions and to aPL titers, whereas nitrative stress relates to low grade inflammation and both phenomena may have implications for thrombosis and atherosclerosis in PAPS Inflammation and immune activation in thrombotic primary antiphospholipid syndrome. To investigate inflammation and immune activation in thrombotic PAPS high-sensitivity CRP (hs-CRP), serum amyloid A (SAA), oxLDL-���2GPI, CRP bound to oxLDL-���2GPI (CRP-oxLDL-���2GPI) (as inflammatory markers) neopterin (NPT) and soluble CD14 (sCD14) (as immune activation markers) were measured by ELISA in 41 PAPS patients, in 44 patients with inherited thrombophilia (IT) and 39 controls (CTR). Compared to other groups, PAPS presented with higher plasma concentrations of inflammatory, hs-CRP (p=0.0004), SAA (p<0.01), CRP-oxLDL-���2GPI (p=0.0004) and immune activation markers, NPT (p<0.0001) and sCD14 (p=0.007). By regression analysis SAA independently predicted thrombosis number (p=0.003) and NPT independently predicted thrombosis type (arterial, p=0.03) and number (p=0.04). These data confirm that low-grade inflammation and immune activation occur and relate to vascular features of PAPS. Antiphosholipid antibodies, haemostatic variables and atherosclerosis in thrombotic primary antiphospholipid syndrome To evaluate whether IgG aCL titre, haemostatic variables and the lipid profile bore any relationship to the intima media thickness (IMT) of carotid arteries high-resolution sonography was applied to the common carotid (CC), carotid bifurcation (CB) and internal carotid (IC) of 42 aPL subjects, 29 with primary thrombotic antiphospholipid syndrome and 13 with persistence of aPL in the absence of any underlying disorder. The following were measured: plasma FNG, vWF, PAI, homocysteine (HC), CHO, TG, HDL, LDL, platelet numbers and aCL of IgG and IgM isotype. By multiple regression analysis, IgG aCL titre independently predicted IMT at all carotid segments examined (p always <0.005). Plasma FNG and HC independently predicted IMT at the CB (p=0.001 and p<0.0001, respectively) and IC (p=0.03 and p<0.0001, respectively). These data strongly support an atherogenic role for IgG aCL in patients with aPL in addition to traditional risk factors. The atherosclerosis hypothesis was investigated in an age and sex-matched case-double-control study including 49 thrombotic PAPS patients (18 M, 31 F, mean age 37 �� 11), 49 thrombotic patients for IT and 49 healthy subjects. Average IMT was always greater in PAPS than control patients (CC: p=0.004, CB: p=0.013, IC: p=0.001). By dividing participants into age tertiles the IMT was greater in the second (CC: p=0.003, CB: p=0.023, IC: p=0.003) and third tertiles (CC: p=0.03, CB: p=0.004, IC: p=0.007). Conclusion: Coagulation activation, fibrinolysis depression, hightened fibrin turnover, oxidative and nitrative stress in parallel with low grade inflammation and immune activation characterise thrombotic PAPS: all these are early atherogenic processes and contribute to the demonstrated premature atherosclerosis that should be considered a clinical feature of PAPS.

Efeitos da laquea����o proximal dos vasos curtos e da fundoplicatura total sobre a microcircula����o do fundo g��strico : estudo microvascular em cobaias

RESUMO: A opera����o de Nissen, por laparoscopia, �� considerada a cirurgia antirefluxo mais adequada por ser a que melhor replica a fisiologia normal da v��lvula gastresof��gica na maioria dos doentes com sintomas t��picos de doen��a do refluxo gastresof��gico (DRGE). S��o crit��rios t��cnicos o encerramento seguro dos pilares do diafragma e a cria����o de fundoplicatura completa (360 graus), curta (inferior a dois cent��metros), lassa e sem tens��o ��� desiderando para o qual a laquea����o proximal dos vasos curtos g��stricos �� crucial. Realizei a opera����o de Nissen, por laparoscopia, em sessenta mulheres e quarenta homens com DRGE, sem mortalidade operat��ria, no Servi��o de Cirurgia 6 do Hospital dos Capuchos, CHLC, EPE. Os cem doentes apresentavam m��dia et��ria de 46 anos e queixas, com tempo de evolu����o entre 1 e 43 anos, de pirose (90%), regurgita����o (80%), azia (73%), epigastralgias (54%). A endoscopia alta revelou esofagite de grau Savary-Miller 0-I (62%), II (23%), III (8%), IV (7%); h��rnia de deslizamento (71%), h��rnia paraesof��gica (8%), sem h��rnia (21%); a pHmetria de 24h diagnosticou padr��o misto (38%), levantado (20%), deitado (20%), inconclusiva (22%) e a manometria diagnosticou EEI hipot��nico (35%), perist��lise esof��gica normal (88%), hipomotilidade ligeira (5%) e foi omissa (7%). H��rnia hiatal, esofagite grave, inefic��cia do controlo sintom��tico com inibidor da bomba de prot��es e desejo de descontinuidade terap��utica constitu��ram as indica����es para tratamento cir��rgico. Por celioscopia, efetuei laquea����o dos vasos curtos g��stricos (70%), cruroplastia e fundoplicatura total (seda 2/0), curta (dimens��o m��dia 1,5-2 cm), lassa, sem tens��o e sem calibra����o intraoperat��ria do es��fago. A fundoplicatura de Nissen laparosc��pica mostrou-se segura e eficaz no tratamento da DRGE. A sua idoneidade foi ainda comprovada pela normaliza����o da pHmetria de 24 horas e da manometria p��s-operat��rias, com significado estat��stico, num grupo de catorze volunt��rios assintom��ticos. Em catamnese com recuo m��dio 30,7 meses 94% dos indiv��duos persistem assintom��ticos. Interrogando-me acerca das repercuss��es desta opera����o sobre a microcircula����o do fundo g��strico coloquei, como premissa, a possibilidade de na opera����o de Nissen a laquea����o dos vasos curtos poder induzir modifica����o no di��metro arteriolar da parede do fundo g��strico. Para pesquisar a influ��ncia da laquea����o dos vasos curtos g��stricos e da fundoplicatura total sobre o calibre arteriolar da parede do est��mago no c��rdia, no fundo e na regi��o dos vasos curtos g��stricos, idealizei um Projeto de investiga����o experimental em cobaias. O Projeto foi desenvolvido no Centro de Investiga����o do Departamento de Anatomia da FCM-UNL. Para a sua realiza����o obtive autoriza����o da Comiss��o Cient��fica e Pedag��gica da FCM-UNL, requeri a acredita����o como investigador �� Dire����o Geral de Veterin��ria e, por recorrer �� utiliza����o de animais, submeti-o �� Comiss��o de ��tica da FCM-UNL, que o aprovou por unanimidade. Para limitar o n��mero de animais utilizados ao m��nimo necess��rio, calculei, por m��todo estat��stico, a quantidade de cobaias necess��rias. Subdividindo-as num grupo de ensaio (GE), onde realizei a opera����o de Nissen, e num grupo de controlo (GC), onde apenas procedi a tra����o g��strica, defini e apliquei protocolos de anestesia, de cirurgia e de eutan��sia, segundo os princ��pios dos 3R ��� Replacement, Reduction, Refinement da t��cnica de experimenta����o humana de Russell e Burch (1959) ��� uma estrutura ��tica amplamente aceite para a realiza����o de experimenta����o cient��fica humanizada com animais. A utiliza����o das t��cnicas de estudo angiomorfol��gico permitiu-me analisar e descrever a anatomia normal, a vasculariza����o arterial macrosc��pica, a microangioarquitetura, por microscopia eletr��nica de varrimento de moldes de corros��o vascular, e a histologia da parede do est��mago da cobaia. Procedi, tamb��m, �� defini����o dos crit��rios morfol��gicos que considerei suscet��veis de valida����o deste modelo animal para o estudo proposto. Por raz��es acad��micas, foi necess��rio abreviar o Projeto encurtando, em cerca de dois anos, o prazo dispon��vel para conclus��o do estudo. Apreciando-o com o Gabinete de An��lise Epidemiol��gica e Estat��stica do Centro de Investiga����o do CHLC, EPE, optou-se, perante a escassez de elementos ap��s j�� terem sido recrutados 46 animais, por uma amostra, suplementar, de dimens��o de conveni��ncia de oito cobaias (quatro em cada grupo), condicionada pelo limite temporal universit��rio e pelo respeito pela dignidade dos animais. Neste subgrupo procedi, por microscopia eletr��nica de varrimento, �� medi����o dos calibres arteriolares nos moldes vasculares do c��rdia, do fundo e da zona dos vasos curtos g��stricos tanto no GC como no GE efetuando 469 medi����es no primeiro e 461 no ��ltimo. Os dados foram enviados ao Centro de Investiga����o do CHLC, EPE que procedeu �� sua an��lise estat��stica (ANOVA). A referida an��lise revelou que as arter��olas do plexo mucoso e as do plexo submucoso do c��rdia, do fundo e da regi��o dos vasos curtos g��stricos, mostraram aumento de calibre no GE. O aumento foi, estatisticamente, significativo por ser superior a 50% do calibre do GC. Nos vasos curtos, a diferen��a foi mais pequena, mas persistiu sendo, estatisticamente, significativa. Os vasos retos dilataram na base, na sua emerg��ncia do plexo seroso, apenas no fundo g��strico. Na cobaia a opera����o de Nissen ��� fundoplicatura total com laquea����o dos vasos curtos g��stricos ���, provocou vasodilata����o arteriolar do fundo g��strico. Considero que essa vasodilata����o constituiu acomoda����o �� modifica����o introduzida e infiro que o mesmo possa acontecer no ser humano. Admito, assim, que tamb��m ocorra vasodilata����o no ser humano, na sequ��ncia da laquea����o dos vasos curtos g��stricos, pela analogia microvascular entre as duas esp��cies e que essa vasodilata����o corresponda, igualmente, a um mecanismo de adapta����o arteriolar visando, por exemplo, suprir a perda incorrida pela laquea����o. A associa����o experimental entre laquea����o dos vasos curtos g��stricos e realiza����o de fundoplicatura total, que exerce aumento inerente de press��o sobre a JEG, n��o s�� n��o provocou d��fice da microcircula����o do es��fago distal ou do est��mago proximal como desencadeou um mecanismo de vasodilata����o f��ndica que refor��a o conceito de seguran��a da opera����o de Nissen para tratamento da DRGE. -------------- ABSTRACT: The laparoscopic Nissen operation is considered to be the most appropriate antirefluxsurgery because it suitably replicates the standard physiology of the gastroesophageal valve in most patients with typical symptoms of gastroesophageal reflux disease (GERD). The technical criteria includes the safe shutdown of the diafragmatic crura(cruroplasty) and the creation of a complete fundoplication (360 degrees), short (lesser than two inches), floppy and without tension ��� a goal for which the proximal ligation of the gastric short vessels is crucial. The laparoscopic Nissen operation was performed in sixty women and forty men with GERD, without any operative mortality, at the Surgical Department of the Hospital dos Capuchos, CHLC, EPE. The one hundred patients, averaged 46 years old, complained of heartburn (90%), regurgitation (80%) and upper abdominal pain (54 %). The endoscopy process revealed Savary-Miller esophagitis of grade 0-I (62%), II (23%), III (8%), IV (7%), sliding hernia (71%), paraesophageal hernia (8%) or no herniation (21%). The pHmetry/24h diagnosed mixed pattern (38%), raised (20%), lying (20%) or inconclusive (22%). The manometry diagnosed hypotensive LES (35%), normal esophageal peristalsis (88%), mild hypomotility (5%) and was absent (7%). Hiatal hernia, severe esophagitis, ineffective symptomatic control with proton pump inhibitor and request for treatment discontinuation were the signs for surgical action. A laparoscopic ligation of short gastric vessels (70%), cruroplasty and fundoplication (silk 2/0), short (average size 1.5���2 cm) and floppy, without tension and without intraoperative calibration of the esophagus were thus performed. The laparoscopic Nissen fundoplication behaved safe and effective in treating GERD. In a group of 14 asymptomatic volunteers its reputation was confirmed with statistical significance by normalization of postoperative pHmetry/24h and manometry. 94% of the individuals remained asymptomatic up to 30.7 months (average) in the follow-up. Interrogating myself about the impact of this operation on the microcirculation of the gastric fundus I put premised on the possibility of the ligation of the short gastric vessels in the Nissen procedure can induce changes in the arteriolar diameter in the Wall of the gastric fundus. To explore the influence of ligation of the short gastric vessels and the fundoplication at the arteriolar caliber of the cardia, the fundus and the region of the short vessels of the gastric wall, I designed a project of experimental research in guinea pigs with two interdependent components: one veterinary and another technical where I applied angiomorphological studies. The project was developed at the Research Centre of the Department of Anatomy FCMUNL. For its accomplishment I got permission from the Scientific and Pedagogical Committee of the FCM-UNL, I requested for accreditation as a researcher at the General Directorate of Veterinary and, by resorting to the use of animals I submitted it to the Ethics Committee of the FCM-UNL, which approved it unanimously. The guinea pigs were divided into two experimental groups: an experimental group (EG), in which the Nissen procedure was performed and a control group (CG) in which only a gastric traction was done. Protocols of anesthesia, surgery and euthanasia were applied according to the 3Rs ��� Replacement, Reduction, Refinement of the technique of human experimentation of Burch and Russell (1959) ��� a widely accepted ethical framework for conducting scientific experiments using animals humanely. Using histological and angiomorphological techniques, I performed the analysis and the description of the normal, macro and microvascular, anatomy of the guinea pig stomach and I defined the morphological criteria that I considered susceptible for validation of this animal model for the proposed study. By means of scanning electron microscopy I measured the arteriolar calibers of the vascular casts of the cardia, of the fundus and of the short gastric vessels in both CG and EG, making 469 measurements in the former and 461 in the latter. The data were sent to the Research Center of the CHLC which conducted the statistical analysis (ANOVA). The data were sent to the Centre for Research of the CHLC, EPE which proceeded to statistical analysis (ANOVA). This analysis revealed that the arterioles plexus of the mucosal and submucosal plexus of the cardia, fundus and region of the short gastric vessels, showed increased caliber in EG. The increase was statistically significant for being greater than 50% CG gauge. In the short gastric vessels, the difference was smaller, but persisted and statistically significant. Straight vessels were dilated at the base, on its emergence of the plexus serous only in the fundus. In the guinea pig, the Nissen procedure - complete fundoplication with ligation of the short gastric vessels - caused arteriolar vasodilation on the gastric fundus. I believe that this vasodilation constituted some accommodation to the modification introduced and infer that the same might happen in humans. I admit therefore that vasodilation also occurs in humans following the ligation of the short gastric vessels by microvascular analogy between the two species and that this vasodilation corresponds also to na adaptation mechanism arteriolar, for example, to compensate the loss incurred by ligation. The association of experimental ligation of the short gastric vessels with conducting complete fundoplication, which exerts increased pressure on the EGJ, not only did not cause a microcirculation deficit of the distal esophagus or proximal stomach as triggered a mechanism of fundic vasodilation which reinforces the security concept of the Nissen procedure for treatment of GERD.

Upgrade of an experimental volumetric unit for gas adsorption equilibrium studies

In this work, a volumetric unit previously assembled by the research group was upgraded. This unit revamping was necessary due to the malfunction of the solenoid valves employed in the original experimental setup, which were not sealing the gas properly leading to erroneous adsorption equilibrium measurements. Therefore, the solenoid valves were substituted by manual ball valves. After the volumetric unit improvement its operation was validated. For this purpose, the adsorption equilibrium of carbon dioxide (CO2) at 323K and 0 - 20 bar was measured on two different activated carbon samples, in the of extrudates (ANG6) and of a honeycomb monolith (ACHM). The adsorption equilibrium results were compared with data previously measured by the research group, using a high-pressure microbalance from Rubotherm GmbH (Germany) ��� gravimetric. The results obtained using both apparatuses are coincident thus validating the good operation of the volumetric unit upgraded in this work. Furthermore, the adsorption equilibrium of CO2 at 303K and 0 - 10 bar on Metal-Organic Frameworks (MOFs) Cu-BTC and Fe-BTC was also studied. The CO2 adsorption equilibrium results for both MOFs were compared with the literature results showing good agreement, which confirms the good quality of the experimental results obtained in the new volumetric unit. Cu-BTC sample showed significantly higher CO2 adsorption capacity when compared with the Fe-BTC sample. The revamping of the volumetric unit included a new valve configuration in order to allow testing an alternative method for the measurement of adsorption equilibrium. This new method was employed to measure the adsorption equilibrium of CO2 on ANG6 and ACHM at 303, 323 and 353K within 0-10 bar. The good quality of the obtained experimental data was testified by comparison with data previously obtained by the research group in a gravimetric apparatus.

Fisiopatologia da microcircula����o coron��ria e perfus��o do miorc��rdio : ecocardiografia de contraste do mioc��rdio e doppler transtor��cico

RESUMO: Este trabalho tentou contribuir para a caracteriza����o da fisiopatologia da microcircula����o coron��ria em diferentes formas de patologia com o aux��lio da ecocardiografia transtor��cica. Com a aplica����o da ecocardiografia Doppler transtor��cica foi efectuado o estudo da reserva coron��ria da art��ria descendente anterior e com a ecocardiografia de contraste do mioc��rdio foram analisados par��metros de perfus��o do mioc��rdio como a velocidade da microcircula����o coron��ria, o volume de sangue mioc��rdico e a reserva de fluxo mioc��rdico. Estas t��cnicas foram utilizadas em diferentes situa����es fisiopatol��gicas com particular interesse na hipertrofia ventricular esquerda de diferentes etiologias como a hipertens��o arterial, estenose a��rtica e cardiomiopatia hipertr��fica. Tamb��m na diabetes mellitus tipo 2 e na doen��a coron��ria ateroscler��tica, estud��mos as altera����es da microcircula����o coron��ria. Com a mesma t��cnica de ecocardiografia de contraste do mioc��rdio foi analisada a perfus��o do mioc��rdio num modelo experimental animal sujeito a uma dieta aterog��nica. Al��m das conclus��es espec��ficas em rela����o a cada um dos trabalhos efectuados h�� a referir como conclus��es gerais a sua f��cil aplicabilidade e exequibilidade em ��mbito cl��nico, a sua reprodutibilidade e precis��o. Quando comparadas com t��cnicas consideradas de refer��ncia mostraram resultados com significativa correla����o estat��stica. Em todos os doentes e nos grupos controle foi poss��vel comprovar e quantificar o gradiente de perfus��o transmural em repouso e durante a ac����o de stress vasodilatador, relevando a import��ncia da perfus��o sub-endoc��rdica na fun����o do ventr��culo esquerdo. O estudo da microcircula����o coron��ria no grupo de doentes com hipertrofia ventricular esquerda revelou que no grupo com hipertens��o arterial existe disfun����o da microcircula����o coron��ria ainda antes de se observar aumento de massa do ventr��culo esquerdo, e que esta disfun����o �� diferente em fun����o da geometria ventricular. Nos doentes com estenose a��rtica foi demonstrado que al��m da disfun����o da microcircula����o coron��ria, explicada pelo fen��meno de hipertrofia, existe outro componente extr��nseco que depois de corrigido atrav��s de cirurgia de substitui����o valvular, conduziu a uma parcial normaliza����o dos valores de reserva coron��ria. Na cardiomiopatia hipertr��fica observou-se uma grande heterogeneidade de perfus��o transmural e foi documentado, em imagens de ecocardiografia de contraste do mioc��rdio e ap��s an��lise param��trica, a aus��ncia de perfus��o do mioc��rdio na regi��o sub-endoc��rdica durante o stress vasodilatador de reserva coron��ria diminu��dos em fases precoces de evolu����o da doen��a. Foi demonstrado que a reserva coron��ria na DM2 em fases mais avan��adas estava significativamente diminu��da. Descrevemos tamb��m em doentes com DM2 e sem doen��a coron��ria angiogr��fica a exist��ncia de disfun����o da microcircula����o coron��ria. Durante o stress vasodilatador, observ��mos e document��mos neste grupo de doentes, a exist��ncia de defeitos de perfus��o transit��rios ou de diminui����o da velocidade da microcircula����o coron��ria. No grupo de doentes com doen��a coron��ria confirm��mos o interesse da avalia����o da reserva coron��ria ap��s interven����o percut��nea na defini����o de progn��stico p��s EAM, em termos de recupera����o funcional do ventr��culo esquerdo. Em doentes com BCRE e de dif��cil estratifica����o de risco, foi poss��vel calcular o valor de reserva coron��ria e estratificar o risco de doen��a coron��ria. Num modelo experimental animal demonstr��mos a exequibilidade da t��cnica de ECM, e verific��mos que nessas condi����es experimentais, uma sobrecarga aterog��nica na dieta, ao fim de 6 semanas, comprometia severamente a reserva coron��ria. Estes resultados foram parcialmente revers��veis quando �� dieta foi adicionada uma estatina. Estas t��cnicas pela sua n��o invasibilidade, f��cil acesso, repetibilidade e inocuidade perspectivam-se de grande utilidade na caracteriza����o de doentes com disfun����o da microcircula����o coron��ria, nas diferentes ��reas de diagn��stico, terap��utica e preven����o. A possibilidade de adaptar a t��cnica em modelos experimentais animais tamb��m nos parece poder vir a ter grande utilidade em investiga����o.----------------ABSTRACT: This work is intended to be a contribution to the study of coronary microcirculation applying new echocardiographic techniques as transthoracic Doppler echocardiography of coronary arteries and myocardial contrast echocardiography. Coronary flow reserve may be assessed by transthoracic Doppler echocardiography, and important functional microcirculation parameters as microcirculation flow velocity, myocardial blood volume and myocardial flow reserve may be evaluated through myocardial contrast echocardiography. Microcirculation was analysed in different pathophysiological settings. We addressed situations with increased left ventricular mass as systemic arterial hypertension, aortic stenosis and hypertrophic cardiomyopathy. Also coronary microcirculation was studied in type 2 Diabetes and in different clinical forms of atherosclerotic coronary artery disease. Specific and detailed conclusions were withdrawn from each experimental work. In the overall it was concluded that these two techniques were important tools to easily assess specific pathophysiological information about coronary microcirculation at bed side which would be difficult to get through other techniques. When compared with gold standard techniques, similar sensibility and specificity was found. Because of their better temporal and spatial resolution it was possible to analyse the importance of transmural perfusion gradients, both in basal and during vasodilatation, and their relation to ischemia, and mechanical wall kinetics, as wall thickening and motion. Coronary microcirculation dysfunction was found in systemic arterial hypertension early evolution stages, also related to different left ventricular geometric patterns. Different etiopathogenical explanations for aortic stenosis coronary microcirculation dysfunction were analysed and compared after aortic valve replacement. Transmural myocardial perfusion heterogeneity pattern was observed in hypertrophic cardiomyopathy which was aggravated during adenosine challenge. Coronary microcirculation dysfunction was diagnosed in type 2 diabetes both with coronary artery disease and with normal angiographic coronary arteries. Dynamic transitory subendocardial perfusion defects with adenosine vasodilatation were visualized in these patients.In patients with left branch block, transthoracic Doppler echocardiography was able to suggest a coronary reserve cut-off value for risk stratification. Also it was possible with this technique to calculate coronary flow reserve and predict restenosis after PTCA Again, in an experimental animal model, applying myocardial contrast echocardiography technique it was possible to study the consequences of an atherogenic diet and statins action on the coronary microcirculation function. Because these techniques are easily performed at bed side, are harmless, use no ionizing radiation and because of their repeatability, reproducibility and accuracythey are promissory tools to assess coronary microcirculation. Both in clinic and research areas these techniques will probably have a role in clinical diagnosis, prevention and therapeutically decision.