Registratie van ascorbinaatverdunningscurven en van veranderingen in Po2 en bloedstroomsnelheid met onbekende gepolariseerde Pt-elektrodes.

Indicator dilution technics have found widespread use in cardio vascular research since the routine application of cardiac catherization. The fundamentals of these technics date back to Fick, Stewart and Hamilton• Especially oximetry and dye dilution gained much attention and application. After the introduction of the intravascular Pt-electrode as detector for H2 and ascorbate by Clark29•30 , these methods drew much interest, a great variety of applications having since been published. Especially the use of inhaled H2 as indicator and a so-called potentiometric Pt-electrode as detector was used in many investigations, primarily in the evaluation of circulatory shunts. This method however, has the disadvantage of giving only qualitative information. The use of a polarized Pt-electrode for the detection of injected ascorbate as indicator has the benefit of a linear relationship between signal and concentration. The disadvantage of polarized electrodes in a flowing medium is the dependency of the signal on the flow velocity. This drawback limited the application of ascorbate dilution technics, while furthermore most of the available electrodes were, or soon became, insensitive to ascorbate..

Cellular aging in cardiovascular diseases

As we progress to a society with an increasing average age, the problems that are associated with advanced age becoming more prominent. This is particularly visible by the increase onset of aging associated diseases, such as atherosclerosis, heart failure and diabetes mellitus type II. On a cellular level, the process of cellular aging is termed cellular senescence and the number of senescent cells in an organism increases in an age dependent manner. In our research we focused on the presence and development of cellular senescence in cardiovascular diseases. The role of the telomeres and the enzyme telomerase during aging, and in cardiovascular diseases is discussed. In a model for telomere shortening we describe that telomere length is associated with a striking decrease in voluntary exercise, but this was not directly associated with a cardiovascular phenotype. In the second part of this thesis we focus more on endothelial senescence and the pathways that are involved in the prevention of senescence. In endothelial cell culture models and in a model for diabetes type II we show that cellular senescence can be prevented by activating specific receptors that are present on the endothelial cells. Although these results have to be extended with studies in a human population, these results give new fundamental insights into the development of cellular senescence and open up new targets that eventually might help to fight the deleterious effects of cellular aging in cardiovascular diseases.

The quality of caring relationships

In health care, relationships between patients or disabled persons and professionals are at least co-constitutive for the quality of care. Many patients complain about the contacts and communication with caregivers and other professionals. From a care-ethical perspective a good patient-professional relationship requires a process of negotiation and shared understanding about mutual normative expectations. Mismatches between these expectations will lead to misunderstandings or conflicts. If caregivers listen to the narratives of identity of patients, and engage in a deliberative dialogue, they will better be able to attune their care to the needs of patients. We will illustrate this with the stories of three women with multiple sclerosis. Their narratives of identity differ from the narratives that caregivers and others use to understand and identify them. Since identities give rise to normative expectations in all three cases there is a conflict between what the women expect of their caregivers and vice-versa. These stories show that the quality of care, defined as doing the right thing, at the right time, in the right way, for the right person, is dependent on the quality of caring relationships