Projects / Programmes
Role of Calcium and lipid membranes in survival of critically ill patients
| Code |
Science |
Field |
Subfield |
| 3.06.00 |
Medical sciences |
Cardiovascular system |
|
| Code |
Science |
Field |
| B007 |
Biomedical sciences |
Medicine (human and vertebrates) |
| Code |
Science |
Field |
| 3.02 |
Medical and Health Sciences |
Clinical medicine |
blood coagulation, factor Xa, dimerization, lipid membranes rich in phosphatidylserine, calcium, blood clots, artificial blood vessel, EPR, NMR, optical microscopy
Researchers (14)
Organisations (3)
Abstract
Role of calcium and lipid membranes in survival of critically ill patients
The Problem
Critical illness is a life-threatening multi-system process with high mortality. It is common for critically ill patients to suffer from abnormalities in blood coagulation, ranging from isolated thrombocytopenia to complex defects, such as disseminated intravascular coagulation (DIC). DIC is proposed to result from insufficient physiologic anticoagulation pathways, although the exact etiology is not yet defined.
State of the Art
Blood coagulation abnormalities in critically ill patients are commonly accompanied by:
1) low calcium (Ca2+) concentration (hypocalcaemia), and by
2) increased concentrations of various forms of phosphatidylserine-containing membranes (PS-containing membranes), such as endothelial micro particles, in blood.
The existing literature suggested a link between Ca2+ and the availability of PS-containing membranes in regulating blood coagulation; however, the biochemical nature of this link has not been defined yet (Figure 1, yellow triangle).
Research Goal & Potential Effects of the Results
The proposed project is therefore aimed at clarifying the biochemical nature of the possible link among low concentration of Ca2+, increased concentration of PS-containing membranes, and initial phase of blood coagulation. In this way we hope to contribute to the development of new therapeutic methods which will improve survival of critically ill patients.
The search for the possible missing link will be based on our previous work on factor Xa (fXa) (Koklic & Majumder, 2009 & 2013, Biochemistry), which is one of the key enzymes in initiating blood coagulation. fXa requires calcium and PS-containing membranes to reach physiologically significant activity. However, only recently we have shown that PS-containing membranes can also inhibit fXa activity, but only at high Ca2+ and low concentration of PS-containing membranes. This is just the opposite of conditions observed in critical illness, suggesting that fXa might not be sufficiently inhibited in critical illness. The inhibition is a consequence of formation of inactive fXa dimers on membranes at higher than normal concentration of Ca2+. These findings present a key question of how Ca2+ and PS-containing membranes regulate fXa activity, especially at physiological conditions.
Figure 1. Proposed etiology of critical illness, which will be explored in the proposed project.
Hypothesis
In this project we will investigate formation of inactive fXa dimers on PS-containing membrane surfaces at different concentrations of calcium (Figure 2 in next State of the art section) to answer whether regulation of fXa by calcium and PS-containing membranes could have a role in preventing uncontrolled systemic activation of blood coagulation, which might be the case in critically ill patients.
Methods, Project Organization & Novelty of Expected Results
The originality of the proposed project is in precise control of both Ca2+ and PS-membrane concentration, which was typically overlooked in previous research. In this project we will investigate heretofore poorly understood processes of fXa binding, dimerization and subsequent inactivation of fXa on PS-containing membranes. Since these processes represent a complex system, its characterization requires numerical data analysis of several independent experimental data sets, which will be obtained using different experimental techniques, such as: EPR, NMR, and different optical microscopy techniques.
The likelihood of successful implementation of the project is high, since the leader of the proposed project has been collaborating already for several years with top researchers in hematology from the School of Medicine, University of North Carolina, and with the recipient of the Nobel Prize for Physiology or Medicine for 2007. The proposed project also includes active patricipation of researchers from Facu
Significance for science
In the proposed project we clarified yet unknown molecular mechanisms of factor Xa regulation which influence initiation of blood coagulation. This contributed to the development of the blood coagulation field and added missing pieces of basic knowledge about the coagulation cascade. We continued development of recently developed method of fluorescence microspectroscopy, work on this project therefore also contributed to the development of new experimental methods.
Significance for the country
Results of our research are published in prestigious Biochemical journal and were presented at international conferences, universities and institutes. This contributed to the international promotion of Slovenia. Researchers of the project group collaborated with two research groups from the USA, thus researchers, especially young ones, gained access to the knowledge and expertise of dr. Lentz’s group as well as to the knowledge of dr. Smithies, who is known to unselfishly shares his expertise. The project facilitated education of young scientists, which gained experience in interdisciplinary field of natural sciences and physiology. Professor Oliver Smithies and his wife Nobuyo Maeda visited us between 8th and 11th September 2014 in the framework of our scientific collaboration between laboratory of biophysics at Solid state physics department at IJS and University of North Carolina at Chapel Hill. Professor Smithies is a Nobel laureate for medicine for the year 2007, he had a lecture at Wednesday Colloquium at IJS with a title “Where do ideas come from”. He also visited prime minister of the Republic of Slovenia and minister of science, where he argued for greater support of science.
Most important scientific results
Annual report
2014,
2015,
final report
Most important socioeconomically and culturally relevant results
Final report
