Timo Savunen

In Vivo Detection of Vascular Adhesion Protein-1 in Experimental Inflammation

Vascular adhesion protein-1 (VAP-1) is an inflammation-inducible endothelial glycoprotein which mediates leukocyte-endothelial cell interactions. To study the pathogenetic significance of VAP-1 in inflammatory disorders, an in vivo immunodetection method was used to detect the regulation of luminally expressed VAP-1 in experimental skin and joint inflammation in the pig and dog. Moreover, VAP-1 was studied as a potential target to localize inflammation by radioimmunoscintigraphy. Up-regulation of VAP-1 in experimental dermatitis and arthritis could be visualized by specifically targeted immunoscintigraphy. Moreover, the translocation of VAP-1 to the functional position on the endothelial surface was only seen in inflamed tissues. These results suggest that VAP-1 is both an optimal candidate for anti-adhesive therapy and a potential target molecule for imaging inflammation.

Myocardial viability: Fluorine-18-deoxyglucose positron emission tomography in prediction of wall motion recovery after revascularization

To assess the value of positron emission tomography (PET) imaging with fluorine-18-deoxyglucose ([18F]FDG) in predicting cardiac wall motion recovery after revascularization, 48 consecutive patients with previous myocardial infarction were studied. The normalized [18F]FDG uptake at rest was assessed semiquantitatively and compared to perfusion at rest as studied by SPECT imaging. Wall motion was analyzed with echocardiography before and after revascularization. Wall motion recovery occurred in 27 (30%) of the revascularized 90 dysfunctional segments. Preserved [18F]FDG uptake (mean +/- 2 SD) was commonly found in dysfunctional segments, but only 54% of these segments recovered after revascularization. Subnormal [18F]FDG uptake identified accurately the segments with no potential to recover (predictive value 100%). By using an optimized threshold value for normalized [18F]FDG uptake, the sensitivity of 85% and specificity of 84% to predict functional recovery were reached simultaneously. However, in the segments with moderately or severely reduced perfusion at rest, the diagnostic accuracy of [18F]FDG uptake for viability was 100%. The results of this study show that the presence of viable tissue indicated by preserved [18F]FDG uptake does not inevitably imply functional recovery after revascularization. However, acceptable diagnostic accuracy for viability might be reached by [18F]FDG alone, providing that appropriate uptake limits are used. The combined evaluation of [18F]FDG uptake and perfusion enables precise assessment of myocardial viability.

Fatty Acid Metabolism in the Liver, Measured by Positron Emission Tomography, Is Increased in Obese Individuals

BACKGROUND & AIMS Hepatic lipotoxicity results from and contributes to obesity-related disorders. It is a challenge to study human metabolism of fatty acids (FAs) in the liver. We combined (11)C-palmitate imaging by positron emission tomography (PET) with compartmental modeling to determine rates of hepatic FA uptake, oxidation, and storage, as well as triglyceride release in pigs and human beings. METHODS Anesthetized pigs underwent (11)C-palmitate PET imaging during fasting (n = 3) or euglycemic hyperinsulinemia (n = 3). Metabolic products of FAs were measured in arterial, portal, and hepatic venous blood. The imaging methodology then was tested in 15 human subjects (8 obese subjects); plasma (11)C-palmitate kinetic analyses were used to quantify systemic and visceral lipolysis. RESULTS In pigs, PET-derived and corresponding measured FA fluxes (FA uptake, esterification, and triglyceride FA release) did not differ and were correlated with each other. In human beings, obese subjects had increased hepatic FA oxidation compared with controls (mean +/- standard error of the mean, 0.16 +/- 0.01 vs 0.08 +/- 0.01 micromol/min/mL; P = .0007); FA uptake and esterification rates did not differ between obese subjects and controls. Liver FA oxidation correlated with plasma insulin levels (r = 0.61, P = .016), adipose tissue (r = 0.58, P = .024), and systemic insulin resistance (r = 0.62, P = .015). Hepatic FA esterification correlated with the systemic release of FA into plasma (r = 0.71, P = .003). CONCLUSIONS PET imaging can be used to measure FA metabolism in the liver. By using this technology, we found that obese individuals have increased hepatic oxidation of FA, in the context of adipose tissue insulin resistance, and increased FA flux from visceral fat. FA flux from visceral fat is proportional with the mass of the corresponding depot.

Infective endocarditis in a Finnish teaching hospital: a study on 326 episodes treated during 1980–2004

Objectives: To evaluate potential changes of infective endocarditis (IE) in patients treated in a Finnish teaching hospital during the past 25 years. Patients: 326 episodes of IE in 303 patients treated during 1980–2004 were evaluated for clinical characteristics and their changes over time. Results: The mean age of the patients increased with time (from 47.2 to 54.5 years, p  =  0.003). Twenty-five (7.7%) episodes were associated with intravenous drug use (IVDU), with a significant increase of these episodes after 1996 (from 0 to 19 (20%), p < 0.001). Viridans streptococci were the most common causative agents of IE during 1980–1994, but after that Staphylococcus aureus was the most common pathogen (p  =  0.015). The proportion of IE of the aortic valve decreased during the study (from 30 (49%) to 26 (27%), whereas the proportions of mitral (11 (18%) to 33 (35%) and tricuspid valve IE (0 to 13 (14%) increased correspondingly (p  =  0.001). This was mainly due to more patients with IVDU. Chronic dialysis for renal failure as an underlying condition increased over time (from 0 to 7 (7.4%), p  =  0.015) but no other predisposing conditions changed. Complications such as neurological manifestations and heart failure did not change in frequency, but the incidence of lung emboli increased (from 0% to 10.5%, p < 0.001); 83% of these emboli occurred in patients with IVDU. The proportion of patients requiring surgical treatment and mortality due to IE did not change. Conclusions: During these 25 years, the causative agents, affected valves and complications of IE changed to some degree. These changes were mainly attributed to the increase of IVDU-associated IE. Except for the increase in age, the clinical presentation and outcome in non-addicts remained substantially unchanged.

IFN-beta protects from vascular leakage via up-regulation of CD73.

Changes in endothelial permeability are crucial in the pathogenesis of many diseases. Adenosine is one of the endogenous mediators controlling endothelial permeability under normal conditions, and an endothelial cell surface enzyme CD73 is a key regulator of adenosine production. Here we report that IFN‐β is a novel inducer of CD73. We found that pretreatment with IFN‐β dramatically improved the vascular barrier function in lungs after intestinal ischemia‐reperfusion injury in wild‐type animals in vivo. IFN‐β had absolutely no protective effects in CD73‐deficient mice, which suffered from more severe lung damage than wild‐type mice, showing that IFN‐β functions strictly in a CD73‐dependent manner. Most importantly, IFN‐β treatment initiated after the ischemic period almost completely inhibited vascular leakage during the reperfusion. IFN‐β also induced the expression and activity of CD73 and concurrently decreased vascular permeability in cultured human pulmonary endothelial cells. These data show that induction of CD73 and improvement of vascular barrier are new mechanisms for the anti‐inflammatory action of IFN‐β. Moreover, IFN‐β treatment may be useful in alleviating vascular leakage induced by ischemia‐reperfusion injury.

Long-term outcome of infective endocarditis: a study on patients surviving over one year after the initial episode treated in a Finnish teaching hospital during 25 years.

BackgroundOnly a few previous studies have focused on the long-term prognosis of the patients with infective endocarditis (IE). Our purpose was to delineate factors potentially associated with the long-term outcome of IE, recurrences of IE and requirement for late valve surgery.MethodsA total of 326 episodes of IE in 303 patients were treated during 1980–2004 in the Turku University Hospital. We evaluated the long-term outcome and requirement for late valve surgery for 243 of these episodes in 226 patients who survived longer than 1 year after the initial admission. Factors associated with recurrences were analysed both for the 1-year survivors and for all 303 patients.ResultsThe mean (SD) follow-up time for the 1-year survivors was 11.5 (7.3) years (range 25 days to 25.5 years). The overall survival was 95%, 82%, 66%, 51% and 45% at 2, 5, 10, 15 and 20 years. In age and sex adjusted multivariate analyses, significant predictors for long-term overall mortality were heart failure within 3 months of admission (HR 1.97, 95% CI 1.27 to 3.06; p = 0.003) and collagen disease (HR 2.54, 95% CI 1.25 to 5.19; p = 0.010) or alcohol abuse (HR 2.39, 95% CI 1.30 to 4.40; p = 0.005) as underlying conditions, while early surgery was significantly associated with lower overall mortality rates (HR 0.31, 95% CI 0.17 to 0.58; p < 0.001). Heart failure was also significantly associated with the long-term cardiac mortality (p = 0.032). Of all 303 patients, 20 had more than 1 disease episode. Chronic dialysis (p = 0.002), intravenous drug use (p = 0.002) and diabetes (p = 0.015) were significant risk factors for recurrent episodes of IE, but when analysed separately for the 1-year survivors, only chronic dialysis remained significant (p = 0.017). Recurrences and late valve surgery did not confer a poor prognosis.ConclusionHeart failure during the index episode of IE was the complication, which significantly predicted a poor long-term outcome. Patients who underwent surgery during the initial hospitalisation for IE faired significantly better than those who did not.

Annulo-aortic ectasia. Light and electron microscopic changes in aortic media

The aortic wall of the human ascending aorta from 44 patients operated on for annulo-aortic ectasia (AAE) was studied. Light microscopy revealed significantly greater cystic change, elastic fragmentation, fibrosis and disappearance of smooth muscle cells in aortic media in AAE than in control specimens taken at autopsy. Occasional aortae, however, were morphologically almost normal. Eight of the patients had Marfans syndrome. No significant differences were observed between them and the other 36 patients, except for a tendency to have less pronounced fibrosis. There were 9 patients who, in addition to the changes mentioned, had advanced atherosclerosis, and their aortae showed more extensive fibrosis and medial necrosis. Pooling of proteoglycan matrix, degeneration of elastic lamellae, increased amount of collagen and necrosis of smooth muscle cells characterized the electron microscopic findings of 13 patients. The collagen fibers seemed to be of normal shape. In conclusion, changes in annulo-aortic ectasia are characterized by severe cystic medial necrosis. The changes are basically similar in Marfan and non-Marfan patients.

Effects of dexmedetomidine on coronary hemodynamics and myocardial oxygen balance

Objective: α2-Adrenergic agonists decrease central sympathetic outflow and maintain normal transmural myocardial blood flow distribution, but intravenous bolus doses of these agents can also induce excessive coronary vasoconstriction and myocardial ischemia. The hypothesis of the present study was that a rapid intravenous bolus of dexmedetomidine, a specific α2-adrenergic agonist, will cause coronary vasoconstriction and accompanying myocardial ischemia in young pigs. Design: Prospective, controlled study on experimental animals. Setting: Animal laboratory of a university cardiorespiratory research center. Participants: Twelve domestic 8-week-old open-chest pigs, anesthetized with high-dose fentanyl. Another six pigs served as controls. Interventions: Sequential intravenous dexmedetomidine boluses of 3, 10, and 30 mg/kg were administered, and responses were measured during peak changes (2 minutes after injection) and during recovery after each dose. Measurements and Main Results: Left anterior descending coronary artery blood flow, calculated regional coronary vascular resistance, myocardial extraction of oxygen and lactate, plasma catecholamine levels, and conventional central hemodynamic parameters were measured. The two higher doses of dexmedetomidine induced 21% and 29% immediate increases in left anterior descending coronary artery blood flow. At the same time mean systemic blood pressure and pulmonary capillary wedge pressure increased, and calculated regional coronary vascular resistance increased. Myocardial extraction of oxygen and lactate remained unchanged. Conclusions: Large intravenous doses of dexmedetomidine caused moderate regional coronary vasoconstriction without metabolic signs of myocardial ischemia in young domestic pigs at the same time as a marked vasoconstrictive response in the systemic circulation.

Non-invasive estimation of hepatic blood perfusion from H2 15O PET images using tissue-derived arterial and portal input functions

PurposeThe liver is perfused through the portal vein and the hepatic artery. When its perfusion is assessed using positron emission tomography (PET) and 15O-labeled water (H215O), calculations require a dual blood input function (DIF), i.e., arterial and portal blood activity curves. The former can be generally obtained invasively, but blood withdrawal from the portal vein is not feasible in humans. The aim of the present study was to develop a new technique to estimate quantitative liver perfusion from H215O PET images with a completely non-invasive approach.MethodsWe studied normal pigs (n = 14) in which arterial and portal blood tracer concentrations and Doppler ultrasonography flow rates were determined invasively to serve as reference measurements. Our technique consisted of using model DIF to create tissue model function and the latter method to simultaneously fit multiple liver time–activity curves from images. The parameters obtained reproduced the DIF. Simulation studies were performed to examine the magnitude of potential biases in the flow values and to optimize the extraction of multiple tissue curves from the image.ResultsThe simulation showed that the error associated with assumed parameters was <10%, and the optimal number of tissue curves was between 10 and 20. The estimated DIFs were well reproduced against the measured ones. In addition, the calculated liver perfusion values were not different between the methods and showed a tight correlation (r = 0.90).ConclusionIn conclusion, our results demonstrate that DIF can be estimated directly from tissue curves obtained through H215O PET imaging. This suggests the possibility to enable completely non-invasive technique to assess liver perfusion in patho-physiological studies.

Ischemia-reperfusion injury is attenuated in VAP-1-deficient mice and by VAP-1 inhibitors

Neutrophils mediate the damage caused by ischemia‐reperfusion both at the site of primary injury and in remote organs. Vascular adhesion protein‐1 (VAP‐1) is an ectoenzyme expressed on endothelial cells and it has been shown to regulate leukocyte extravasation. Here we show for the first time using VAP‐1‐deficient mice that VAP‐1 plays a significant role in the intestinal damage and acute lung injury after ischemia‐reperfusion. Separate inhibition of VAP‐1 by small molecule enzyme inhibitors and a function‐blocking monoclonal antibody in WT mice revealed that the catalytic activity of VAP‐1 is responsible for its pro‐inflammatory action. The use of transgenic humanized VAP‐1 mice also showed that the enzyme inhibitors alleviate both the ischemia‐reperfusion injury in the gut and neutrophil accumulation in the lungs. These data thus indicate that VAP‐1 regulates the inflammatory response in ischemia‐reperfusion injury and suggest that blockade of VAP‐1 may have therapeutic value.