VEGF-C and angiopoietins in lymphangiogenesis

Angiogenesis and lymphangiogenesis occur during development as the result of tightly coordinated signalling programs to generate two hierarchically organised vascular systems. All tissues and organs are dependent on a functional blood vasculature for oxygen and nutrients, whereas the lymphatic vasculature functions to collect excess tissue fluid, passing it through lymph nodes for immune surveillance, and returning it to the blood circulation. Effectors that control developmental angiogenesis and lymphangiogenesis are also involved in pathological settings, and therefore potential targets for therapy. Vascular endothelial growth factor (VEGF) and angiopoietin (Ang) growth factors, signalling through endothelial VEGFR and Tie receptors, have been established as key regulators of angiogenic and lymphangiogenic processes in development and disease. In this study, we aimed to obtain a clearer understanding of the vascular effects of stimulation by VEGF-C, Ang1 and Ang2, all known to be involved in lymphangiogenesis. In cell culture models, we found that both intrinsic and microenvironmental regulatory mechanisms are involved in the regulation of endothelial cell phenotypes, and distinct responses to VEGF signalling are induced by specific receptor pathways in different endothelial cell types. Surprisingly, we also found that Ang1 induces sprouting lymphangiogenesis in vivo by a VEGFR-3 dependent mechanism, establishing Ang1 as a novel lymphangiogenic factor. Using inducible transgenic mouse models, we found that VEGF-C-induced lymphatic hyperplasia persisted independently of the growth factor, indicating that short pro-lymphangiogenic therapy could lead to lasting improvements in tissue oedema. While VEGF-C had blood vessel effects in embryos, no angiogenic side effects were observed in adult tissues. Furthermore, inducible transgenic expression of Ang2 during embryonic development confirmed Ang2 as an important regulator of lymphatic remodelling and mural cell contacts. The unexpected similarity of the lymphatic maturation defects caused by excess Ang2 to those observed in Ang2 deficient mice demonstrated that correct doses of Ang2 are crucial for the control of lymphatic development. Unlike Ang1, Ang2 did not induce lymphatic sprouting. Although Ang1 has been shown to be able to substitute for Ang2 during developmental lymphangiogenesis, their lymphatic effects are not identical. These findings further our understanding of the basic mechanisms of angiogenesis and lymphangiogenesis, important for the future development of targeted therapies for vascular diseases such as cancer, inflammation, lymphoedema and ischemia. VEGF-C and Ang1 especially emerged as promising candidates for pro-lymphangiogenic therapy.

VEGF-C/VEGFR-3 and PDGF-B/PDGFR-b pathways in embryonic lymphangiogenesis

The circulatory system comprises the blood vascular system and the lymphatic vascular system. These two systems function in parallel. Blood vessels form a closed system that delivers oxygen and nutrients to the tissues and removes waste products from the tissues, while lymphatic vessels are blind-ended tubes that collect extravasated fluid and cells from the tissues and return them back to blood circulation. Development of blood and lymphatic vascular systems occurs in series. Blood vessels are formed via vasculogenesis and angiogenesis whereas lymphatic vessels develop via lymphangiogenesis, after the blood vascular system is already functional. Members of the vascular endothelial growth factor (VEGF) family are regulators of both angiogenesis and lymphangiogenesis, while members of the platelet-derived growth factor (PDGF) family are major mitogens for pericytes and smooth muscle cells and regulate formation of blood vessels. Vascular endothelial growth factor C (VEGF-C) is the major lymphatic growth factor and signaling through its receptor vascular endothelial growth factor receptor 3 (VEGFR-3) is sufficient for lymphangiogenesis in adults. We studied the role of VEGF-C in embryonic lymphangiogenesis and showed that VEGF-C is absolutely required for the formation of lymph sacs from embryonic veins. VEGFR-3 is also required for normal development of the blood vascular system during embryogenesis, as Vegfr3 knockout mice die at mid-gestation due to failure in remodeling of the blood vessels. We showed that sufficient VEGFR-3 signaling in the embryo proper is required for embryonic angiogenesis and in a dosage-sensitive manner for embryonic lymphangiogenesis. Importantly, mice deficient in both VEGFR-3 ligands, Vegfc and Vegfd, developed a normal blood vasculature, suggesting VEGF-C- and VEGF-D- independent functions for VEGFR-3 in the early embryo. Platelet-derived growth factor B (PDGF-B) signals via PDGFR-b and regulates formation of blood vessels by recruiting pericytes and smooth muscle cells around nascent endothelial tubes. We showed that PDGF-B fails to induce lymphangiogenesis when overexpressed in adult mouse skin using adenoviral vectors. However, mouse embryos lacking Pdgfb showed abnormal lymphatic vessels, suggesting that PDGF-B plays a role in lymphatic vessel maturation and separation from blood vessels during embryogenesis. Lymphatic vessels play a key role in immune surveillance, fat absorption and maintenance of fluid homeostasis in the body. However, lymphatic vessels are also involved in various diseases, such as lymphedema and tumor metastasis. These studies elucidate the basic mechanisms of embryonic lymphangiogenesis and add to the knowledge of lymphedema and tumor metastasis treatments by giving novel insights into how lymphatic vessel growth could be induced (in lymphedema) or inhibited (in tumor metastasis).

A quantum chemical investigation of the metal centres in cytochrome c oxidase

Quantum effects are often of key importance for the function of biological systems at molecular level. Cellular respiration, where energy is extracted from the reduction of molecular oxygen to water, is no exception. In this work, the end station of the electron transport chain in mitochondria, cytochrome c oxidase, is investigated using quantum chemical methodology. Cytochrome c oxidase contains two haems, haem a and haem a3. Haem a3, with its copper companion, CuB, is involved in the final reduction of oxygen into water. This binuclear centre receives the necessary electrons from haem a. Haem a, in turn, receives its electrons from a copper ion pair in the vicinity, called CuA. Density functional theory (DFT) has been used to clarify the charge and spin distributions of haem a, as well as changes in these during redox activity. Upon reduction, the added electron is shown to be evenly distributed over the entire haem structure, important for the accommodation of the prosthetic group within the protein. At the same time, the spin distribution of the open-shell oxidised state is more localised to the central iron. The exact spin density distribution has been disputed in the literature, however, different experiments indicating different distributions of the unpaired electron. The apparent contradiction is shown to be due to the false assumption of a unit amount of unpaired electron density; in fact, the oxidised state has about 1.3 unpaired electrons. The validity of the DFT results have been corroborated by wave function based coupled cluster calculations. Point charges, for use in classical force field based simulations, have been parameterised for the four metal centres, using a newly developed methodology. In the procedure, the subsystem for which point charges are to be obtained, is surrounded by an outer region, with the purpose of stabilising the inner region, both electronically and structurally. Finally, the possibility of vibrational promotion of the electron transfer step between haem a and a3 has been investigated. Calculating the full vibrational spectra, at DFT level, of a combined model of the two haems, revealed several normal modes that do shift electron density between the haems. The magnitude of the shift was found to be moderate, at most. The proposed mechanism could have an assisting role in the electron transfer, which still seems to be dominated by electron tunnelling.

Lymphatic vessels in health and disease: Role of the VEGF-C/VEGFR-3 pathway and the transcription factor FOXC2

The circulatory system consists of two vessel types, which act in concert but significantly differ from each other in several structural and functional aspects as well as in mechanisms governing their development. The blood vasculature transports oxygen, nutrients and cells to tissues whereas the lymphatic vessels collect extravasated fluid, macromolecules and cells of the immune system and return them back to the blood circulation. Understanding the molecular mechanisms behind the developmental and functional regulation of the lymphatic system long lagged behind that of the blood vasculature. Identification of several markers specific for the lymphatic endothelium, and the discovery of key factors controlling the development and function of the lymphatic vessels have greatly facilitated research in lymphatic biology over the past few years. Recognition of the crucial importance of lymphatic vessels in certain pathological conditions, most importantly in tumor metastasis, lymphedema and inflammation, has increased interest in this vessel type, for so long overshadowed by its blood vascular cousin. VEGF-C (Vascular Endothelial Growth Factor C) and its receptor VEGFR-3 are essential for the development and maintenance of embryonic lymphatic vasculature. Furthermore, VEGF-C has been shown to be upregulated in many tumors and its expression found to positively correlate with lymphatic metastasis. Mutations in the transcription factor FOXC2 result in lymphedema-distichiasis (LD), which suggests a role for FOXC2 in the regulation of lymphatic development or function. This study was undertaken to obtain more information about the role of the VEGF-C/VEGFR-3 pathway and FOXC2 in regulating lymphatic development, growth, function and survival in physiological as well as in pathological conditions. We found that the silk-like carboxyterminal propeptide is not necessary for the lymphangiogenic activity of VEGF-C, but enhances it, and that the aminoterminal propeptide mediates binding of VEGF-C to the neuropilin-2 coreceptor, which we suggest to be involved in VEGF-C signalling via VEGFR-3. Furthermore, we found that overexpression of VEGF-C increases tumor lymphangiogenesis and intralymphatic tumor growth, both of which could be inhibited by a soluble form of VEGFR-3. These results suggest that blocking VEGFR-3 signalling could be used for prevention of lymphatic tumor metastasis. This might prove to be a safe treatment method for human cancer patients, since inhibition of VEGFR-3 activity had no effect on the normal lymphatic vasculature in adult mice, though it did lead to regression of lymphatic vessels in the postnatal period. Interestingly, in contrast to VEGF-C, which induces lymphangiogenesis already during embryonic development, we found that the related VEGF-D promotes lymphatic vessel growth only after birth. These results suggest, that the lymphatic vasculature undergoes postnatal maturation, which renders it independent of ligand induced VEGFR-3 signalling for survival but responsive to VEGF-D for growth. Finally, we show that FOXC2 is necessary for the later stages of lymphatic development by regulating the morphogenesis of lymphatic valves, as well as interactions of the lymphatic endothelium with vascular mural cells, in which it cooperates with VEGFR-3. Furthermore, our study indicates that the absence of lymphatic valves, abnormal association of lymphatic capillaries with mural cells and an increased amount of basement membrane underlie the pathogenesis of LD. These findings have given new insight into the mechanisms of normal lymphatic development, as well as into the pathogenesis of diseases involving the lymphatic vasculature. They also reveal new therapeutic targets for the prevention and treatment of tumor metastasis and lymphatic vascular failure in certain forms of lymphedema. Several interesting questions were posed that still need to be addressed. Most importantly, the mechanism of VEGF-C promoted tumor metastasis and the molecular nature of the postnatal lymphatic vessel maturation remain to be elucidated.

Redox-linked proton transfer by cytochrome c oxidase

The respiratory chain is found in the inner mitochondrial membrane of higher organisms and in the plasma membrane of many bacteria. It consists of several membrane-spanning enzymes, which conserve the energy that is liberated from the degradation of food molecules as an electrochemical proton gradient across the membrane. The proton gradient can later be utilized by the cell for different energy requiring processes, e.g. ATP production, cellular motion or active transport of ions. The difference in proton concentration between the two sides of the membrane is a result of the translocation of protons by the enzymes of the respiratory chain, from the negatively charged (N-side) to the positively charged side (P-side) of the lipid bilayer, against the proton concentration gradient. The endergonic proton transfer is driven by the flow of electrons through the enzymes of the respiratory chain, from low redox-potential electron donors to acceptors of higher potential, and ultimately to oxygen. Cytochrome c oxidase is the last enzyme in the respiratory chain and catalyzes the reduction of dioxygen to water. The redox reaction is coupled to proton transport across the membrane by a yet unresolved mechanism. Cytochrome c oxidase has two proton-conducting pathways through which protons are taken up to the interior part of the enzyme from the N-side of the membrane. The K-pathway transfers merely substrate protons, which are consumed in the process of water formation at the catalytic site. The D-pathway transfers both substrate protons and protons that are pumped to the P-side of the membrane. This thesis focuses on the role of two conserved amino acids in proton translocation by cytochrome c oxidase, glutamate 278 and tryptophan 164. Glu278 is located at the end of the D-pathway and is thought to constitute the branching point for substrate and pumped protons. In this work, it was shown that although Glu278 has an important role in the proton transfer mechanism, its presence is not an obligatory requirement. Alternative structural solutions in the area around Glu278, much like the ones present in some distantly related heme-copper oxidases, could in the absence of Glu278 support the formation of a long hydrogen-bonded water chain through which proton transfer from the D-pathway to the catalytic site is possible. The other studied amino acid, Trp164, is hydrogen bonded to the ∆-propionate of heme a3 of the catalytic site. Mutation of this amino acid showed that it may be involved in regulation of proton access to a proton acceptor, a pump site, from which the proton later is expelled to the P-side of the membrane. The ion pair that is formed by the ∆-propionate of heme a3 and arginine 473 is likely to form a gate-like structure, which regulates proton mobility to the P-side of the membrane. The same gate may also be part of an exit path through which water molecules produced at the catalytically active site are removed towards the external side of the membrane. Time-resolved optical and electrometrical experiments with the Trp164 to phenylalanine mutant revealed a so far undetected step in the proton pumping mechanism. During the A to PR transition of the catalytic cycle, a proton is transferred from Glu278 to the pump site, located somewhere in the vicinity of the ∆-propionate of heme a3. A mechanism for proton pumping by cytochrome c oxidase is proposed on the basis of the presented results and the mechanism is discussed in relation to some relevant experimental data. A common proton pumping mechanism for all members of the heme-copper oxidase family is moreover considered.

Membrane Insertion of C-tail Anchored Proteins

The correct localization of proteins is essential for cell viability. In order to achieve correct protein localization to cellular membranes, conserved membrane targeting and translocation mechanisms have evolved. The focus of this work was membrane targeting and translocation of a group of proteins that circumvent the known targeting and translocation mechanisms, the C-tail anchored protein family. Members of this protein family carry out a wide range of functions, from protein translocation and recognition events preceding membrane fusion, to the regulation of programmed cell death. In this work, the mechanisms of membrane insertion and targeting of two C-tail anchored proteins were studied utilizing in vivo and in vitro methods, in yeast and mammalian cell systems. The proteins studied were cytochrome b(5), a well characterized C-tail anchored model protein, and N-Bak, a novel member of the Bcl-2 family of regulators of programmed cell death. Membrane insertion of cytochrome b(5) into the endoplasmic reticulum membrane was found to occur independently of the known protein conducting channels, through which signal peptide-containing polypeptides are translocated. In fact, the membrane insertion process was independent of any protein components and did not require energy. Instead membrane insertion was observed to be dependent on the lipid composition of the membrane. The targeting of N-Bak was found to depend on the cellular context. Either the mitochondrial or endoplasmic reticulum membranes were targeted, which resulted in morphological changes of the target membranes. These findings indicate the existence of a novel membrane insertion mechanism for C-tail anchored proteins, in which membrane integration of the transmembrane domain, and the translocation of C-terminal fragments, appears to be spontaneous. This mode of membrane insertion is regulated by the target membrane fluidity, which depends on the lipid composition of the bilayer, and the hydrophobicity of the transmembrane domain of the C-tail anchored protein, as well as by the availability of the C-tail for membrane integration. Together these mechanisms enable the cell to achieve spatial and temporal regulation of sub-cellular localization of C-tail anchored proteins.

Oxygen reduction and proton translocation by cytochrome c oxidase

Energy conversion by living organisms is central dogma of bioenergetics. The effectiveness of the energy extraction by aerobic organisms is much greater than by anaerobic ones. In aerobic organisms the final stage of energy conversion occurs in respiratory chain that is located in the inner membrane of mitochondria or cell membrane of some aerobic bacteria. The terminal complex of the respiratory chain is cytochrome c oxidase (CcO) - the subject of this study. The primary function of CcO is to reduce oxygen to water. For this, CcO accepts electrons from a small soluble enzyme cytochrome c from one side of the membrane and protons from another side. Moreover, CcO translocates protons across the membrane. Both oxygen reduction and proton translocation contributes to generation of transmembrane electrochemical gradient that is used for ATP synthesis and different types of work in the cell. Although the structure of CcO is defined with a relatively high atomic resolution (1.8 Å), its function can hardly be elucidated from the structure. The electron transfer route within CcO and its steps are very well defined. Meanwhile, the proton transfer roots were predicted from the site-specific mutagenesis and later proved by X-ray crystallography, however, the more strong proof of the players of the proton translocation machine is still required. In this work we developed new methods to study CcO function based on FTIR (Fourier Transform Infrared) spectroscopy. Mainly with use of these methods we answered several questions that were controversial for many years: [i] the donor of H+ for dioxygen bond splitting was identified and [ii] the protolytic transitions of Glu-278 one of the key amino acid in proton translocation mechanism was shown for the first time.

Theoretical Studies on Coupled Electron and Proton Transfer in Cytochrome c Oxidase

The complexity of life is based on an effective energy transduction machinery, which has evolved during the last 3.5 billion years. In aerobic life, the utilization of the high oxidizing potential of molecular oxygen powers this machinery. Oxygen is safely reduced by a membrane bound enzyme, cytochrome c oxidase (CcO), to produce an electrochemical proton gradient over the mitochondrial or bacterial membrane. This gradient is used for energy-requiring reactions such as synthesis of ATP by F0F1-ATPase and active transport. In this thesis, the molecular mechanism by which CcO couples the oxygen reduction chemistry to proton-pumping has been studied by theoretical computer simulations. By building both classical and quantum mechanical model systems based on the X-ray structure of CcO from Bos taurus, the dynamics and energetics of the system were studied in different intermediate states of the enzyme. As a result of this work, a mechanism was suggested by which CcO can prevent protons from leaking backwards in proton-pumping. The use and activation of two proton conducting channels were also enlightened together with a mechanism by which CcO sorts the chemical protons from pumped protons. The latter problem is referred to as the gating mechanism of CcO, and has remained a challenge in the bioenergetics field for more than three decades. Furthermore, a new method for deriving charge parameters for classical simulations of complex metalloenzymes was developed.

Myoblast transplantation and adenoviral VEGF-C transfer in porcine model of coronary artery disease

Heart failure is a common and highly challenging medical disorder. The progressive increase of elderly population is expected to further reflect in heart failure incidence. Recent progress in cell transplantation therapy has provided a conceptual alternative for treatment of heart failure. Despite improved medical treatment and operative possibilities, end-stage coronary artery disease present a great medical challenge. It has been estimated that therapeutic angiogenesis would be the next major advance in the treatment of ischaemic heart disease. Gene transfer to augment neovascularization could be beneficial for such patients. We employed a porcine model to evaluate the angiogenic effect of vascular endothelial growth factor (VEGF)-C gene transfer. Ameroid-generated myocardial ischemia was produced and adenovirus encoding (ad)VEGF-C or β-galactosidase (LacZ) gene therapy was given intramyocardially during progressive coronary stenosis. Angiography, positron emission tomography (PET), single photon emission computed tomography (SPECT) and histology evidenced beneficial affects of the adVEGF-C gene transfer compared to adLacZ. The myocardial deterioration during progressive coronary stenosis seen in the control group was restrained in the treatment group. We observed an uneven occlusion rate of the coronary vessels with Ameroid constrictor. We developed a simple methodological improvement of Ameroid model by ligating of the Ameroid–stenosed coronary vessel. Improvement of the model was seen by a more reliable occlusion rate of the vessel concerned and a formation of a rather constant myocardial infarction. We assessed the spontaneous healing of the left ventricle (LV) in this new model by SPECT, PET, MRI, and angiography. Significant spontaneous improvement of myocardial perfusion and function was seen as well as diminishment of scar volume. Histologically more microvessels were seen in the border area of the lesion. Double staining of the myocytes in mitosis indicated more cardiomyocyte regeneration at the remote area of the lesion. The potential of autologous myoblast transplantation after ischaemia and infarction of porcine heart was evaluated. After ligation of stenosed coronary artery, autologous myoblast transplantation or control medium was directly injected into the myocardium at the lesion area. Assessed by MRI, improvement of diastolic function was seen in the myoblast-transplanted animals, but not in the control animals. Systolic function remained unchanged in both groups.

Measurement of the Λb0 Lifetime in Λb0→Λc+π- Decays in pp̅ Collisions at √s=1.96 TeV

We report a measurement of the lifetime of the Lambda_b baryon in decays to the Lambda_C+ pi- final state in a sample corresponding to 1.1 fb^-1 collected in p-pbar collisions at sqrt(s) = 1.96 TeV by the CDF II detector at the Tevatron collider. Using a sample of about 3000 fully reconstructed Lambda_b events we measure tau(Lambda_b) = 1.401 +- 0.046 (stat) +- 0.035 (syst) ps (corresponding to c.tau(Lambda_b) = 420.1 +- 13.7 (stat) +- 10.6 (syst) um, where c is the speed of light). The ratio of this result and the world average B^0 lifetime yields tau(Lambda_b)/tau(B^0) = 0.918 +- 0.038 (stat and syst), in good agreement with recent theoretical predictions.

First measurement of the ratio of branching fractions B(Λb0→Λc+μ-ν̅ μ)/B(Λb0→Λc+π-)

This article presents the first measurement of the ratio of branching fractions B(Λb0→Λc+μ-ν̅ μ)/B(Λb0→Λc+π-). Measurements in two control samples using the same technique B(B̅ 0→D+μ-ν̅ μ)/B(B̅ 0→D+π-) and B(B̅ 0→D*(2010)+μ-ν̅ μ)/B(B̅ 0→D*(2010)+π-) are also reported. The analysis uses data from an integrated luminosity of approximately 172  pb-1 of pp̅ collisions at √s=1.96  TeV, collected with the CDF II detector at the Fermilab Tevatron. The relative branching fractions are measured to be B(Λb0→Λc+μ-ν̅ μ)/B(Λb0→Λc+π-)=16.6±3.0(stat)±1.0(syst)+2.6/-3.4(PDG)±0.3(EBR), B(B̅ 0→D+μ-ν̅ μ)/B(B̅ 0→D+π-)= 9.9±1.0(stat)±0.6(syst)±0.4(PDG)±0.5(EBR), and B(B̅ 0→D*(2010)+μ-ν̅ μ)/B(B̅ 0→D*(2010)+π-)=16.5±2.3(stat)± 0.6(syst)±0.5(PDG)±0.8(EBR). The uncertainties are from statistics (stat), internal systematics (syst), world averages of measurements published by the Particle Data Group or subsidiary measurements in this analysis (PDG), and unmeasured branching fractions estimated from theory (EBR), respectively. This article also presents measurements of the branching fractions of four new Λb0 semileptonic decays: Λb0→Λc(2595)+μ-ν̅ μ, Λb0→Λc(2625)+μ-ν̅ μ, Λb0→Σc(2455)0π+μ-ν̅ μ, and Λb0→Σc(2455)++π-μ-ν̅ μ, relative to the branching fraction of the Λb0→Λc+μ-ν̅ μ decay. Finally, the transverse-momentum distribution of Λb0 baryons produced in pp̅ collisions is measured and found to be significantly different from that of B̅ 0 mesons, which results in a modification in the production cross-section ratio σΛb0/σB̅ 0 with respect to the CDF I measurement.

Phospholipid cytochrome c interactions

The ability of the peripherally associated membrane protein cytochrome c (cyt c) to bind phospholipids in vitro was studied using fluorescence spectroscopy and large unilamellar liposomes. Previous work has shown that cyt c can bind phospholipids using two distinct mecha- nisms and sites, the A-site and the C-site. This binding is mediated by electrostatic or hydrophobic interactions, respectively. Here, we focus on the mechanism underlying these interactions. A chemically modified cyt c mutant Nle91 was used to study the ATP-binding site, which is located near the evolutionarily invariant Arg 91 on the protein surface. This site was also demonstrated to mediate phospholipid binding, possibly by functioning as a phospholipid binding site. Circular dichroism spectroscopy, time resolved fluorescence spectroscopy of zinc- porphyrin modified [Zn2+-heme] cyt c and liposome binding studies of the Nle91 mutant were used to demonstrate that ATP induces a conformational change in membrane- bound cyt c. The ATP-induced conformational changes were mediated by Arg 91 and were most pronounced in cyt c bound to phospholipids via the C-site. It has been previously reported that the hydrophobic interaction between phospho- lipids and cyt c (C-site) includes the binding of a phospholipid acyl chain inside the protein. In this mechanism, which is known as extended phospholipid anchorage, the sn-2 acyl chain of a membrane phospholipid protrudes out of the membrane surface and is able to bind in a hydrophobic cavity in cyt c. Direct evidence for this type of bind- ing mechanism was obtained by studying cyt c/lipid interaction using fluorescent [Zn2+- heme] cyt c and fluorescence quenching of brominated fatty acids and phospholipids. Under certain conditions, cyt c can form fibrillar protein-lipid aggregates with neg- atively charged phospholipids. These aggregates resemble amyloid fibrils, which are involved in the pathogenesis of many diseases. Congo red staining of these fibers con- firmed the presence of amyloid structures. A set of phospholipid-binding proteins was also found to form similar aggregates, suggesting that phospholipid-induced amyloid formation could be a general mechanism of amyloidogenesis.

Cystatin C, a measure of renal function, as prognostic risk marker in acute heart failure : Studies on the cardiorenal syndrome

Acute heart failure (AHF) is a complex syndrome associated with exceptionally high mortality. Still, characteristics and prognostic factors of contemporary AHF patients have been inadequately studied. Kidney function has emerged as a very powerful prognostic risk factor in cardiovascular disease. This is believed to be the consequence of an interaction between the heart and kidneys, also termed the cardiorenal syndrome, the mechanisms of which are not fully understood. Renal insufficiency is common in heart failure and of particular interest for predicting outcome in AHF. Cystatin C (CysC) is a marker of glomerular filtration rate with properties making it a prospective alternative to the currently used measure creatinine for assessment of renal function. The aim of this thesis is to characterize a representative cohort of patients hospitalized for AHF and to identify risk factors for poor outcome in AHF. In particular, the role of CysC as a marker of renal function is evaluated, including examination of the value of CysC as a predictor of mortality in AHF. The FINN-AKVA (Finnish Acute Heart Failure) study is a national prospective multicenter study conducted to investigate the clinical presentation, aetiology and treatment of, as well as concomitant diseases and outcome in, AHF. Patients hospitalized for AHF were enrolled in the FINN-AKVA study, and mortality was followed for 12 months. The mean age of patients with AHF is 75 years and they frequently have both cardiovascular and non-cardiovascular co-morbidities. The mortality after hospitalization for AHF is high, rising to 27% by 12 months. The present study shows that renal dysfunction is very common in AHF. CysC detects impaired renal function in forty percent of patients. Renal function, measured by CysC, is one of the strongest predictors of mortality independently of other prognostic risk markers, such as age, gender, co-morbidities and systolic blood pressure on admission. Moreover, in patients with normal creatinine values, elevated CysC is associated with a marked increase in mortality. Acute kidney injury, defined as an increase in CysC within 48 hours of hospital admission, occurs in a significant proportion of patients and is associated with increased short- and mid-term mortality. The results suggest that CysC can be used for risk stratification in AHF. Markers of inflammation are elevated both in heart failure and in chronic kidney disease, and inflammation is one of the mechanisms thought to mediate heart-kidney interactions in the cardiorenal syndrome. Inflammatory cytokines such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) correlate very differently to markers of cardiac stress and renal function. In particular, TNF-α showed a robust correlation to CysC, but was not associated with levels of NT-proBNP, a marker of hemodynamic cardiac stress. Compared to CysC, the inflammatory markers were not strongly related to mortality in AHF. In conclusion, patients with AHF are elderly with multiple co-morbidities, and renal dysfunction is very common. CysC demonstrates good diagnostic properties both in identifying impaired renal function and acute kidney injury in patients with AHF. CysC, as a measure of renal function, is also a powerful prognostic marker in AHF. CysC shows promise as a marker for assessment of kidney function and risk stratification in patients hospitalized for AHF.

Protein Kinase C and Anaplastic Lymphoma Kinase Targeted Compounds

The protein kinases (PKs) belong to the largest single family of enzymes, phosphotransferases, which catalyze the phosphorylation of other enzymes and proteins and function primarily in signal transduction. Consequently, PKs regulate cell mechanisms such as growth, differentiation, and proliferation. Dysfunction of these cellular mechanisms may lead to cancer, a major predicament in health care. Even though there is a range of clinically available cancer-fighting drugs, increasing number of cancer cases and setbacks such as drug resistance, constantly keep cancer research active. At the commencement of this study an isophthalic acid derivative had been suggested to bind to the regulatory domain of protein kinase C (PKC). In order to investigate the biological effects and structure-activity relationships (SARs) of this new chemical entity, a library of compounds was synthesized. The best compounds induced apoptosis in human leukemia HL-60 cells and were not cytotoxic in Swiss 3T3 fibroblasts. In addition, the best apoptosis inducers were neither cytotoxic nor mutagenic. Furthermore, results from binding affinity assays of PKC isoforms revealed the pharmacophores of these isophthalic acid derivatives. The best inhibition constants of the tested compounds were measured to 210 nM for PKCα and to 530 nM for PKCδ. Among natural compounds targeting the regulatory domain of PKC, the target of bistramide A has been a matter of debate. It was initially found to activate PKCδ; however, actin was recently reported as the main target. In order to clarify and to further study the biological effects of bistramide A, the total syntheses of the natural compound and two isomers were performed. Biological assays of the compounds revealed accumulation of 4n polyploid cells as the primary mode of action and the compounds showed similar overall antiproliferative activities. However, each compound showed a distinct distribution of antimitotic effect presumably via actin binding, proapoptotic effect presumably via PKCδ, and pro-differentiation effect as evidenced by CD11b expression. Furthermore, it was shown that the antimitotic and proapoptotic effects of bistramide A were not secondary effects of actin binding but independent effects. The third aim in this study was to synthesize a library of a new class of urea-based type II inhibitors targeted at the kinase domain of anaplastic lymphoma kinase (ALK). The best compounds in this library showed IC50 values as low as 390 nM for ALK while the initial low cellular activities were successfully increased even by more than 70 times for NPM-ALK- positive BaF3 cells. More importantly, selective antiproliferative activity on ALK-positive cell lines was achieved; while the best compound affected the BaF3 and SU-DHL-1 cells with IC50 values of 0.5 and 0.8 μM, respectively, they were less toxic to the NPM-ALK-negative human leukemic cells U937 (IC50 = 3.2 μM) and BaF3 parental cells (IC50 = 5.4 μM). Furthermore, SAR studies of the synthesized compounds revealed functional groups and positions of the scaffold, which enhanced the enzymatic and cellular activities.

Campylobacter jejuni and C. coli in Finnish poultry production

Campylobacter, mainly Campylobacter jejuni and C. coli, are worldwide recognized as a major cause of bacterial food-borne gastroenteritis. Epidemiological studies have shown handling or eating of poultry to be significant risk factors for human infections. Campylobacter contamination can occur at all stages of a poultry meat production cycle. The aim of this thesis was to study the occurrence and diversity of Campylobacter in broiler and turkey production in Finland. In summer 1999, 2.9 % of slaughtered broiler flocks were Campylobacter-positive. From the isolated strains 94 % were C. jejuni and 6% were C. coli. During years 2005-2006 one turkey parent flock, the hatchery, six different commercial turkey farms and different stages of the slaughterhouse were monitored during one and the half year. No Campylobacter were detected in either of the samples from the turkey parent flock or from the hatchery using the culture method. Instead PCR detected DNA of Campylobacter from the turkey parent flock and samples from the hatchery. Six out of 12 commercial turkey flocks were found negative at the farm level but only two of those were negative at slaughter. Campylobacter-positive samples within the flock at slaughter were detected between 0% and 94% with evisceration and chilling water being the most critical stages for contamination. All of Campylobacter isolates were shown to be C. jejuni. Campylobacter-positive turkey flocks were colonized by a limited number of Campylobacter genotypes both at the farm and slaughter level. In conclusion, in our first study in 1999 a low prevalence of Campylobacter in Finnish broiler flocks was detected and it has remained at a low level during the study period until the present. In the turkey meat production, we found that flocks which were negative at the farm became contaminated with Campylobacter at the slaughter process. These results suggest that proper and efficient cleaning and disinfection of slaughter and processing premises are needed to avoid cross-contamination. Prevention of colonization at the farm by a high level of biosecurity control and hygiene may be one of the most efficient ways to reduce the amount of Campylobacter-positive poultry meat in Finland. With a persistent low level of Campylobacter-positive flocks, it could be speculated that the use of logistic slaughtering, according to Campylobacter status at farm, might have be advantageous in reducing Campylobacter contamination of retail poultry products. However, the significance of the domestic poultry meat for human campylobacteriosis in Finland should be evaluated.