Endogenous Immunosuppression and the Effect of Blood Transfusion on Cell Mediated Immunity in Haemodialysis Patients

In order to clarify the effect of blood transfusion in uraemic patients, 48 dialysis patients who had not received previous blood transfusion were randomly allocated to receive 5 or 10 units of third-party packed cells at two week intervals. Twelve dialysis patients and 12 healthy subjects who had not received previous blood transfusion were also studied as control groups. The cell-mediated immunity (CMI) of the transfused patients was measured by skin testing with DNCB and four recall antigens before the first transfusion and 14 days after the last unit of blood. In addition, prior to the first and 14 days after each transfusion patients were screened for a) haematological and biochemistry results, b) cytotoxic antibodies, c) complement levels, d) titres of IgG secreting cells (PFC) in the peripheral blood both spontaneously and after stimulation with PWM and SAC, using a protein A plaque assay, and e) prostaglandin E (PGE) production in supernatants from both Con A-stimulated PBMC cultures and unstimulated ones. The two control groups were screened for these parameters on 3-4 occasions over a period of 3 months. The methods and results from this randomised controlled study are described in detail in the first 8 chapters of this thesis. In Chapter 9, I describe results from a large number of patients with regard to factors determining the response to DNCB and its value as a means of predicting renal allograft survival. This retrospective analysis was done from an angle and evidence provided by the prospective study. The aim of the study was, a) to assess the effect of blood transfusion in uraemic patients, b) to see whether patients with strong or weak reaction to DNCB differ in their response to transfusion, and try to define the optimum number of transfusions for each group to achieve a beneficial effect, c) to see whether blood transfusion-induced alterations in immune responses could be monitored with simple skin tests and d) to define possible factors determining the response to DNCB and assess the predictive value of the skin test regarding graft survival. In the group of the previously non-transfused dialysis patients more than half were strong DNCB responders. This proportion was two fold higher compared to that of the overall dialysis population. There was a progressive decline in strong responders as patients received more blood, and in multi-transfused patients CMI was profoundly suppressed. Multivariate analysis revealed that the most significant factor associated with the response to DNCB was blood transfusion. A number of factors did not show any association, namely age, sex, primary renal disease, type of dialysis, parity, ABO and rhesus blood groups, interval between last transfusion and test, cytotoxic antibodies and a number of haematological and biochemical parameters. HLA-DRW6 positive patients were more likely to be strong responders when tested prior to any blood transfusion, but the DRW6 effect was not observed in patients sensitised after one or more transfusions. This suggests that HLA-DRW6 is a marker of strong CMI, but this strong response can be modified by transfusion. Sequential skin testing with DNCB and recall antigens did not reflect changes induced by transfusion, as repeated immunisation resulted in stronger anamnestic responses, regardless of the amount of blood or whether they were transfused at all. Follow-up DNCB skin testing showed that blood transfusion at the time of sensitisation to DNCB was a crucial event for secondary responses to DNCB. Patients eliciting a strong primary response retained and gave even stronger responses on subsequent tests regardless of transfusion status at the time of sensitisation to DNCB. Contrary to that, weak responders who were sensitised after transfusion showed a further depression in their secondary responses, while weak responders sensitised prior to any transfusion were more likely to show increased secondary responses. As a result of this, approximately one third of the latter patients changed to strong responders in follow-up tests. (Abstract shortened by ProQuest.)

Drug use problems with self-injected low-molecular-weight heparins in primary care

Purpose: Outpatient subcutaneous therapies are becoming increasingly common. A literature search failed to find produced any studies on application problems pertaining to the self-injection of low-molecular-weight heparins (LMWH) in a heterogeneous outpatient population under daily-life conditions. We therefore designed a study with the aim of recording drug use problems, patient satisfaction, compliance, problems arising from the injection site (abdomen vs. thigh), and residual drug volumes in pre-filled syringes used in self-injection therapy. Methods: Patients were recruited in community pharmacies by 95 trained Master's students in pharmacy. Data were collected during recruitment and by means of structured questionnaire-based telephone interviews that were carried out at the beginning and the end of the LMWH treatment. Results: The median age of the 213 patients enrolled in the study was 54years [interquartile range (IQR) 39-70 years]; of these, 15.5% had their injections administered by a third person. The rate of self-reported non-compliance was 17.1%. At least one relevant problem was recorded in 85.0% of the cases. At the end of the treatment, 38.9% of the patients stated self-administration of the injections required some effort. The preferred injection site was the thigh (68.5%). An overall mean residual drug volume ≥10.0% was detected for 3.9% of the patients. If residual drug was present, a median of 11.2% (IQR 8.6-17.6%) of the total drug volume had not been injected. Patients injecting into the thigh showed a higher risk of leaving residual medication (odds ratio 2.16, 95% confidence interval 1.04-4.51). Conclusions: Most patients had drug use problems, whereas no clear factors were associated with non-compliance, the injection site (apart from residual drug), and discomfort or effort required (apart from prior injection use

A finite element method for non-linear hyperelasticity applied for the simulation of octopus ARM motions

An implicit non-linear finite element (FE) numerical procedure for the simulation of biological muscular tissues is presented. The method has been developed for studying the motion of muscular hydrostats, such as squid and octopus arms and its general framework is applicable to other muscular tissues. The FE framework considered is suitable for the dynamic numerical simulations of three-dimensional non-linear nearly incompressible hyperelastic materials that undergo large displacements and deformations. Human and animal muscles, consisting of fibers and connective tissues, belong to this class of materials. The stress distribution inside the muscular FE model is considered as the superposition of stresses along the muscular fibers and the connective tissues. The stresses along the fibers are modeled as the sum of active and passive stresses, according to the muscular model of Van Leeuwen and Kier (1997) Philos. Trans. R. Soc. London, 352: 551-571. Passive stress distribution is an experimentally-defined function of fibers’ deformation; while active stress distribution is the product of an activation level time function, a force-stretch function and a force-stretch ratio function. The mechanical behavior of the surrounding tissues is determined adopting a Mooney-Rivlin constitutive model. The incompressibility criterion is met by enforcing large bulk modulus and by introducing modified deformation measures. Due to the non-linear nature of the problem, approximate determination of the Jacobian matrix is performed, in order to utilize the full Newton-Raphson iterative procedure within each time-step. In addition, time discretization is performed via the implicit Newmark method. We developed an open-source finite element code that is capable of simulating large deflection maneuvers of muscular hydrostats. The proposed methodology is validated by comparing the numerical results with existing measurements for the squid arm extension. The efficiency and robustness of the proposed numerical method is demonstrated through a series of octopus arm maneuvers, such as extension, compression and bending

Antiretroviral Therapy Reduces Markers of Endothelial and Coagulation Activation in Patients Infected with Human Immunodeficiency Virus Type 1

We investigated the effect of antiretroviral therapy on vascular activation in 41 human immunodeficiency (HIV)—infected patients receiving a regimen that included either at least 1 protease inhibitor (PI; n = 21) or a nonnucleoside reverse-transcriptase inhibitor (NNRTI; n = 20). Acontrol group of 21 healthy subjectswas included for comparison. Levels of endothelialmarkers (soluble vascular cell adhesion molecule [sVCAM]-1, soluble intercellular adhesionmolecule-1, and vonWillebrand factor) were higher in HIV-infected persons before treatment than in control subjects anddecreasedsignificantlyafter 5-13 months of treatment. Levels of sVCAM-1 and vonWillebrand factor correlated significantly with initial virus load. D-dimer concentrations also decreased significantly after initiation of treatment. PI- and NNRTI-containing regimens had similar effects. Therapy did not reduce levels of the soluble platelet (sP) activation markers sP-selectin and CD40 ligand. The inhibition of markers of vascular activation may counterbalance sequelae of therapy-induced dyslipidemia and potentially prevent development of atherosclerosis in HIVinfected patient

Programmable DARPin-based receptors for the detection of thrombotic markers

Cellular therapies remain constrained by the limited availability of sensors for disease markers. Here we present an integrated target-to-receptor pipeline for constructing a customizable advanced modular bispecific extracellular receptor (AMBER) that combines our generalized extracellular molecule sensor (GEMS) system with a high-throughput platform for generating designed ankyrin repeat proteins (DARPins). For proof of concept, we chose human fibrin degradation products (FDPs) as markers with high clinical relevance and screened a DARPin library for FDP binders. We built AMBERs equipped with 19 different DARPins selected from 160 hits, and found 4 of them to be functional as heterodimers with a known single-chain variable fragments binder. Tandem receptors consisting of combinations of the validated DARPins are also functional. We demonstrate applications of these AMBER receptors in vitro and in vivo by constructing designer cell lines that detect pathological concentrations of FDPs and respond with the production of a reporter and a therapeutic anti-thrombotic protein

Variability between laboratories performing coagulation tests with identical platforms: a nationwide evaluation study.

BACKGROUND While the assessment of analytical precision within medical laboratories has received much attention in scientific enquiry, the degree of as well as the sources causing variation between them remains incompletely understood. In this study, we quantified the variance components when performing coagulation tests with identical analytical platforms in different laboratories and computed intraclass correlations coefficients (ICC) for each coagulation test. METHODS Data from eight laboratories measuring fibrinogen twice in twenty healthy subjects with one out of 3 different platforms and single measurements of prothrombin time (PT), and coagulation factors II, V, VII, VIII, IX, X, XI and XIII were analysed. By platform, the variance components of (i) the subjects, (ii) the laboratory and the technician and (iii) the total variance were obtained for fibrinogen as well as (i) and (iii) for the remaining factors using ANOVA. RESULTS The variability for fibrinogen measurements within a laboratory ranged from 0.02 to 0.04, the variability between laboratories ranged from 0.006 to 0.097. The ICC for fibrinogen ranged from 0.37 to 0.66 and from 0.19 to 0.80 for PT between the platforms. For the remaining factors the ICC's ranged from 0.04 (FII) to 0.93 (FVIII). CONCLUSIONS Variance components that could be attributed to technicians or laboratory procedures were substantial, led to disappointingly low intraclass correlation coefficients for several factors and were pronounced for some of the platforms. Our findings call for sustained efforts to raise the level of standardization of structures and procedures involved in the quantification of coagulation factors