| 1. |
- Schwarz, E, et al.
(författare)
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Reproducible grey matter patterns index a multivariate, global alteration of brain structure in schizophrenia and bipolar disorder
- 2019
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Ingår i: Translational psychiatry. - : Springer Science and Business Media LLC. - 2158-3188. ; 9:1, s. 12-
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Tidskriftsartikel (refereegranskat)abstract
- Schizophrenia is a severe mental disorder characterized by numerous subtle changes in brain structure and function. Machine learning allows exploring the utility of combining structural and functional brain magnetic resonance imaging (MRI) measures for diagnostic application, but this approach has been hampered by sample size limitations and lack of differential diagnostic data. Here, we performed a multi-site machine learning analysis to explore brain structural patterns of T1 MRI data in 2668 individuals with schizophrenia, bipolar disorder or attention-deficit/ hyperactivity disorder, and healthy controls. We found reproducible changes of structural parameters in schizophrenia that yielded a classification accuracy of up to 76% and provided discrimination from ADHD, through it lacked specificity against bipolar disorder. The observed changes largely indexed distributed grey matter alterations that could be represented through a combination of several global brain-structural parameters. This multi-site machine learning study identified a brain-structural signature that could reproducibly differentiate schizophrenia patients from controls, but lacked specificity against bipolar disorder. While this currently limits the clinical utility of the identified signature, the present study highlights that the underlying alterations index substantial global grey matter changes in psychotic disorders, reflecting the biological similarity of these conditions, and provide a roadmap for future exploration of brain structural alterations in psychiatric patients.
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| 2. |
- Avdic, H. B., et al.
(författare)
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Reduced effects of social feedback on learning in Turner syndrome
- 2023
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Turner syndrome is a genetic condition caused by a complete or partial loss of one of the X chromosomes. Previous studies indicate that Turner syndrome is associated with challenges in social skills, but the underlying mechanisms remain largely unexplored. A possible mechanism is a reduced social influence on learning. The current study examined the impact of social and non-social feedback on learning in women with Turner syndrome (n=35) and a sex- and age-matched control group (n=37). Participants were instructed to earn points by repeatedly choosing between two stimuli with unequal probabilities of resulting in a reward. Mastering the task therefore required participants to learn through feedback which of the two stimuli was more likely to be rewarded. Data were analyzed using computational modeling and analyses of choice behavior. Social feedback led to a more explorative choice behavior in the control group, resulting in reduced learning compared to non-social feedback. No effects of social feedback on learning were found in Turner syndrome. The current study thus indicates that women with Turner syndrome may be less sensitive to social influences on reinforcement learning, than the general population.
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| 3. |
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| 4. |
- Elvsashagen, T, et al.
(författare)
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The genetic architecture of human brainstem structures and their involvement in common brain disorders
- 2020
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 11:1, s. 4016-
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Tidskriftsartikel (refereegranskat)abstract
- Brainstem regions support vital bodily functions, yet their genetic architectures and involvement in common brain disorders remain understudied. Here, using imaging-genetics data from a discovery sample of 27,034 individuals, we identify 45 brainstem-associated genetic loci, including the first linked to midbrain, pons, and medulla oblongata volumes, and map them to 305 genes. In a replication sample of 7432 participants most of the loci show the same effect direction and are significant at a nominal threshold. We detect genetic overlap between brainstem volumes and eight psychiatric and neurological disorders. In additional clinical data from 5062 individuals with common brain disorders and 11,257 healthy controls, we observe differential volume alterations in schizophrenia, bipolar disorder, multiple sclerosis, mild cognitive impairment, dementia, and Parkinson’s disease, supporting the relevance of brainstem regions and their genetic architectures in common brain disorders.
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| 5. |
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| 6. |
- Gracias, J., et al.
(författare)
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Cerebrospinal fluid concentration of complement component 4A is increased in first episode schizophrenia
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Schizophrenia risk has been associated with the complement component 4 (C4) genes. Here the authors show that C4A is elevated in individuals with schizophrenia. Postsynaptic density is reduced in schizophrenia, and risk variants increasing complement component 4A (C4A) gene expression are linked to excessive synapse elimination. In two independent cohorts, we show that cerebrospinal fluid (CSF) C4A concentration is elevated in patients with first-episode psychosis (FEP) who develop schizophrenia (FEP-SCZ: median 0.41 fmol/ul [CI = 0.34-0.45], FEP-non-SCZ: median 0.29 fmol/ul [CI = 0.22-0.35], healthy controls: median 0.28 [CI = 0.24-0.33]). We show that the CSF elevation of C4A in FEP-SCZ exceeds what can be expected from genetic risk variance in the C4 locus, and in patient-derived cellular models we identify a mechanism dependent on the disease-associated cytokines interleukin (IL)-1beta and IL-6 to selectively increase neuronal C4A mRNA expression. In patient-derived CSF, we confirm that IL-1beta correlates with C4A controlled for genetically predicted C4A RNA expression (r = 0.39; CI: 0.01-0.68). These results suggest a role of C4A in early schizophrenia pathophysiology.
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| 7. |
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| 8. |
- Malmqvist, Anna, et al.
(författare)
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Increased peripheral levels of TARC/CCL17 in first episode psychosis patients
- 2019
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Ingår i: Schizophrenia Research. - : ELSEVIER. - 0920-9964 .- 1573-2509. ; 210, s. 221-227
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Tidskriftsartikel (refereegranskat)abstract
- Background: Evidence for a link between the pathophysiology of schizophrenia and the immune system is mounting. Altered levels of chemokines in plasma have previously been reported in patients with schizophrenia under antipsychotic medication. Here we aimed to study both peripheral and central chemokine levels in drugnaive or short-time medicated first episode psychosis (FEP) patients. Method: We analyzed nine chemokines in plasma and CSF from 41 FEP patients and 22 healthy controls using electrochemiluminescence assay. Results: In plasma four chemokines; TARC/CCL17, eotaxin/CCL11, MDC/CCL22, IP-10/CXCL10 and in CSF one chemokine; IP-10/CXCL10 showed reliable detection in N50% of the cases. FEP patients displayed increased levels of TARC/CCL17 in plasma compared to healthy controls, 89.6 (IQR 66.2-125.8) pg/mL compared to 48.6 (IQR 28.0-71.7) pg/mL (p = 0.001). The difference was not attributed to confounding factors. Plasma TARC/CCL17 was not associated with PANSS, CGI or GAF scores, neither with cognitive functions. The chemokines eotaxin/CCL11, MDC/CCL22, IP-10/CXCL10 in plasma and IP-10/CXCL10 in CSF did not differ between FEP patients and controls. Conclusion: In line with a previous study showing that chronic patients with schizophrenia display increased plasma TARC/CCL17 levels, we here found an elevation in FEP patients suggesting a role of TARC/CCL17 in early stages of schizophrenia. The exactmechanism of this involvement is still unknown and future longitudinal studies as well as studies of central and peripheral chemokine levels would be of great interest. (C) 2018 Elsevier B.V. All rights reserved.
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| 9. |
- Ostergaard, M., et al.
(författare)
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MRI assessment of early response to certolizumab pegol in rheumatoid arthritis: a randomised, double-blind, placebo-controlled phase IIIb study applying MRI at weeks 0, 1, 2, 4, 8 and 16
- 2015
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Ingår i: Annals of the Rheumatic Diseases. - : BMJ. - 0003-4967 .- 1468-2060. ; 74:6, s. 1156-1163
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Tidskriftsartikel (refereegranskat)abstract
- Objectives To identify the first time point of an MRI-verified response to certolizumab pegol (CZP) therapy in patients with rheumatoid arthritis (RA). Methods Forty-one patients with active RA despite disease-modifying antirheumatic drug therapy were randomised 2:1 to CZP (CZP loading dose 400mg every 2weeksat weeks 0-4; CZP 200mg every 2weeksat weeks 6-16) or placeboCZP (placebo at weeks 0-2; CZP loading dose at weeks 2-6; CZP 200mg every 2weeks at weeks 8-16). Contrast-enhanced MRI of one hand and wrist was acquired at baseline (week 0) and weeks 1, 2, 4, 8 and 16. All six time points were read simultaneously, blinded to time, using the Outcome Measures in Rheumatology Clinical Trials RA MRI scoring system. Primary outcome was change in synovitis score in the CZP group; secondary outcomes were change in bone oedema (osteitis) and erosion scores and clinical outcome measures. Results Forty patients were treated (27 CZP, 13 placeboCZP), and 36 (24 CZP, 12 placeboCZP) completed week 16. In the CZP group, there were significant reductions from baseline synovitis (Hodges-Lehmann estimate of median change, -1.5, p=0.049) and osteitis scores (-2.5, p=0.031) at week 16. Numerical, but statistically insignificant, MRI inflammation reductions were observed at weeks 1-2 in the CZP group. No significant change was seen in bone erosion score. Improvements across all clinical outcomes were seen in the CZP group. Conclusions CZP reduced MRI synovitis and osteitis scores at week 16, despite small sample size and the technical challenge of reading six time points simultaneously. This study provides essential information on optimal MRI timing for subsequent trials.
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| 18. |
- Engberg, Anna E., 1982-, et al.
(författare)
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EVALUATION OF THE HEMOCOMPATIBILITY OF NOVEL POLYMERIC MATERIALS
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- When a biomaterial surface comes in contact with blood an immediate adsorption of plasma proteins to the surface will occur, and the cascade systems in the blood, such as the complement, coagulation and contact system, will be activated to various degrees. The intensity of this reaction will determine the hemocompatibility of the materials. Here we present an evaluation of the link between the composition, the physico-chemical properties and the protein adsorption properties of six newly synthesized polymers (P1-P6) and the hemocompatibility.The hemocompatibility of the polymeric surfaces was evaluated in human blood plasma and whole blood. Commercially available polyvinylchloride (PVC) was used as reference material. The hemocompatibility of the polymeric surfaces was evaluated with regard to complement activation (C3a and sC5-9 generation) and coagulation activation (platelet loss and TAT-formation) and cytokine productions (27 analytes in multiplex assay) after contact with whole blood. Contact activation was quantified by analyses of FXIIa-C1INH, FXIa-C1INH, and kallikrein-C1INH complexes.Polymers P2 (p<0.05 for C3a), P3, P5 and P6 showed less complement activation, and polymers P1 and P4 (p<0.05 for platelet loss), as well as P5 and P6 showed less coagulation activation compared with reference PVC. Polymers P1-P3 induced activation of the contact system, P3 being the most potent. Secretion of 17 cytokines including chemokines and growth factors were differentially influenced by the polymers, P1 and P3 being significantly (p<0.05) more compatible for five of the analytes.Collectively these data demonstrate that the composition of the polymers clearly leads to different biological properties as a consequence of distinctive physico-chemical properties and protein adsorption patterns.1
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| 19. |
- Engberg, Anna E., et al.
(författare)
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Prediction of inflammatory responses induced by biomaterials in contact with human blood using protein fingerprint from plasma
- 2015
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Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 36, s. 55-65
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Tidskriftsartikel (refereegranskat)abstract
- Inappropriate complement activation is often responsible for incompatibility reactions that occur when biomaterials are used. Complement activation is therefore a criterion included in legislation regarding biomaterials testing. However, no consensus is yet available regarding appropriate complement-activation-related test parameters. We examined protein adsorption in plasma and complement activation/cytokine release in whole blood incubated with well-characterized polymers. Strong correlations were found between the ratio of C4 to its inhibitor C4BP and generation of 10 (mainly pro-inflammatory) cytokines, including IL-17, IFN-gamma, and IL-6. The levels of complement activation products correlated weakly (C3a) or not at all (C5a, sC5b-9), confirming their poor predictive values. We have demonstrated a direct correlation between downstream biological effects and the proteins initially adhering to an artificial surface after contact with blood. Consequently, we propose the C4/C4BP ratio as a robust, predictor of biocompatibility with superior specificity and sensitivity over the current gold standard. (C) 2014 Elsevier Ltd. All rights reserved.
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| 22. |
- Engberg, David L. J., 1986-
(författare)
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Atom Probe Tomography of Hard Nitride and Boride Thin Films
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hard ceramic thin films, including TiSiN, ZrAlN, ZrB2, and ZrTaB2, with applications for wear-resistant coatings, have been studied using atom probe tomography and correlated with several other analytical techniques, including X-ray diffraction, electron microscopy, and elastic recoil detection analysis. Outstanding obstacles for quantitative atom probe tomography of ceramic thin films have been surmounted.Mass spectral overlaps in TiSiN, which make 28Si indistinguishable from 14N, was resolved by isotopic substitution with 15N, and the nanostructural distribution of elements was thus revealed in 3-D, which enabled the identification of additional structural elements within the nanostructured Ti0.81Si0.1915N film. Improvements to the growth model of TiSiN by cathodic arc deposition was suggested.A self-organized nanolabyrinthine structure of ZrAlN, consisting of standing lamellae of fcc-ZrN and hexagonal AlN, was investigated with focus on the onset and limits of the self-organization. The local crystallographic orientational relationships were (001)ZrN || (0001)AlN and <110>ZrN || <2-1-10>AlN. Close to the MgO substrates, a smooth transition region was formed, going from segregated and disordered to the self-organized nanolabyrinthine structure. With increased growth temperature, coarse (111)-oriented ZrN grains occasionally precipitated and locally replaced the nanolabyrinthine structure. Significant local magnification effects rendered the Zr and N signals unusable, thereby inhibiting quantitative compositional analysis of the constituent phases, but the nanostructure was resolved using the Al signal.Ceramic materials are often affected by correlated evaporation, which can result in losses due to the detector dead-time/space. A compositional correction procedure was suggested, tested against an established procedure, and applied to ZrB2. The correction was found to be less dependent on the isotope abundances and background correction compared to the established procedure. While losses due to dead-time/space occur in atom probe tomography of all materials, the correlative field evaporation behavior of ceramics significantly increases the compositional error. The evaporation behavior of ZrB2 was therefore thoroughly investigated and evidence of preferential retention, correlated evaporation, and inhomogeneous field distributions at a low-index pole was presented. The high mass resolution, relatively low multiple events percentage, and quality of the co-evaporation correlation data was partly attributed to the crystal structure and film orientation, which promoted a layer-by-layer field evaporation.The evaporation behavior of the related ZrTaB2 films was found to be similar to that of ZrB2. The distribution of Ta in relation to Zr was investigated, showing that the column boundaries were both metal- and Ta-rich, and that there was a significant amount of Ta in solid solution within the columns.In addition, an instrumental artefact previously not described in atom probe tomography was found in several of the materials investigated in this thesis. The artefact consists of high-density lines along the analysis direction, which cannot be related to pole artefacts. The detection system of the atom probe was identified as the cause, because the artefact patterns on detector histograms coincided with the structure of the microchannel plate. Inconsistencies in the internal boundaries of the microchannel plate multifibers from the manufacturing process can influence the signal to the detector and locally increase the detection efficiency in a pattern characteristic to the microchannel plate in question.Altogether, this thesis shows that atom probe tomography of nitride and boride thin films is burdened by several artefacts and distortions, but that relevant material outcomes can nevertheless be achieved by informed choices of film isotopic constituents and analytical parameters, exclusion of heavily distorted regions (such as pole artefacts), and the use of compositional correction procedures when applicable.
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| 23. |
- Engberg, Elina, et al.
(författare)
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Parental Happiness Associates With the Co-occurrence of Preschool-Aged Children’s Healthy Energy Balance-Related Behaviors
- 2022
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Ingår i: Journal of Happiness Studies. - : Springer Nature. - 1389-4978 .- 1573-7780. ; 23:4, s. 1493-1507
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Tidskriftsartikel (refereegranskat)abstract
- We examined whether parental happiness associate with preschoolers’ healthy energy balance-related behaviors (EBRBs) and with the co-occurrence of multiple healthy EBRBs. This cross-sectional study included 647 pairs of parents (88% mothers) and children (mean age 4.7, SD 0.9 years). Parents completed the Subjective Happiness Scale. In addition, ActiGraph accelerometers measured children’s physical activity, and parents reported screen time and food consumption on behalf of their children. We defined four healthy EBRBs: meeting physical activity guidelines; meeting screen time guidelines; a higher consumption of vegetables, fruits and berries; and a lower consumption of sugary foods, treats and drinks. Parental happiness scores did not associate with children’s healthy EBRBs when each behavior was analyzed separately. However, parents with higher happiness scores were more likely to have a child with 2 or 3–4 healthy EBRBs than a child with 0–1 healthy EBRBs. To conclude, parents who are happier have children with multiple healthy EBRBs. Targeting parental wellbeing should be considered when promoting children’s healthy EBRBs.
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| 33. |
- Erhardt, S, et al.
(författare)
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Kynurenic acid and schizophrenia
- 2003
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Ingår i: Advances in experimental medicine and biology. - Boston, MA : Springer US. - 0065-2598. ; 527, s. 155-165
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Tidskriftsartikel (refereegranskat)
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| 34. |
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| 37. |
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| 38. |
- Hashimoto, Kenji, et al.
(författare)
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Elevated glutamine/glutamate ratio in cerebrospinal fluid of first episode and drug naive schizophrenic patients
- 2005
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Ingår i: BMC Psychiatry. - 1471-244X. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Background: Recent magnetic resonance spectroscopy (MRS) studies report that glutamine is altered in the brains of schizophrenic patients. There were also conflicting findings on glutamate in cerebrospinal fluid (CSF) of schizophrenic patients, and absent for glutamine. This study aims to clarify the question of glutamine and glutamate in CSF of first episode and drug naive schizophrenic patients. Method: Levels of glutamine and glutamate in CSF of 25 first episode and drug-naive male schizophrenic patients and 17 age-matched male healthy controls were measured by a high performance liquid chromatography. Results: The ratio (126.1 (median), 117.7 ± 27.4 (mean ± S.D.)) of glutamine to glutamate in the CSF of patients was significantly (z = -3.29, p = 0.001) higher than that (81.01 (median), 89.1 ± 22.5 (mean ± S.D.)) of normal controls although each level of glutamine and glutamate in patients was not different from that of normal controls. Conclusion: Our data suggests that a disfunction in glutamate-glutamine cycle in the brain may play a role in the pathophysiology of schizophrenia. © 2005 Hashimoto et al, licensee BioMed Central Ltd.
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| 44. |
- Howner, K., et al.
(författare)
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Pharmacological Treatment in Forensic Psychiatry-A Systematic Review
- 2020
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Ingår i: Frontiers in Psychiatry. - : Frontiers Media SA. - 1664-0640. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Background: Pharmacological treatment is of great importance in forensic psychiatry, and the vast majority of patients are treated with antipsychotic agents. There are several systematic differences between general and forensic psychiatric patients, e.g. severe violent behavior, the amount of comorbidity, such as personality disorders and/or substance abuse. Based on that, it is reasonable to suspect that effects of pharmacological treatments also may differ. The objective of this systematic review was to investigate the effects of pharmacological interventions for patients within forensic psychiatry. Methods: The systematic review protocol was pre-registered in PROSPERO (CRD42017075308). Six databases were used for literature search on January 11, 2018. Controlled trials from forensic psychiatric care reporting on the effects of antipsychotic agents, mood stabilizers, benzodiazepines, antidepressants, as well as pharmacological agents used for the treatment of addiction or ADHD, were included. Two authors independently reviewed the studies, evaluated risk of bias and assessed certainty of evidence using Grading of Recommendations Assessment, Development and Evaluation (GRADE). Results: The literature search resulted in 1783 records (titles and abstracts) out of which 10 studies were included. Most of the studies included were retrospective and non-randomized. Five of them focused on treatment with clozapine and the remaining five on other antipsychotics or mood stabilizers. Five studies with a high risk of bias indicated positive effects of clozapine on time from treatment start to discharge, crime-free time, time from discharge to readmission, improved clinical functioning, and reduction in aggressive behavior. Psychotic symptoms after treatment were more pronounced in the clozapine group. Mainly due to the high risk of bias the reliability of the evidence for all outcomes was assessed as very low. Conclusion: This systematic review highlights the shortage of knowledge on the effectiveness of pharmacological treatment within forensic psychiatry. Due to very few studies being available in this setting, as well as limitations in their execution and reporting, it is challenging to overview the outcomes of pharmacological interventions in this context. The frequent use of antipsychotics, sometimes in combination with other pharmacological agents, in this complex and heterogeneous patient group, calls for high-quality studies performed in this specific setting.
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| 45. |
- Leppänen, Marja H., et al.
(författare)
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Comparing estimates of physical activity in children across different cut-points and the associations with weight status
- 2022
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : John Wiley & Sons. - 0905-7188 .- 1600-0838. ; 32:6, s. 971-983
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to compare sedentary time (SED) and intensity-specific physical activity (PA) estimates and the associations of SED and PA with body mass index (BMI) and waist circumference (WC) using three different sets of cut-points in preschool-aged children. A total of 751 children (4.7 ± 0.9 years, boys 52.7%) wore an ActiGraph GT3X+BT accelerometer on their hip for 7 days (24 h). Euclidean norm −1 G with negative values rounded to zero (ENMO) and activity counts from vertical axis (VACounts) and vector magnitude (VMCounts) were derived. Estimates of SED and light, moderate, vigorous, and moderate-to-vigorous PA (MVPA) were calculated for commonly used cut-points by Hildebrand et al., Butte et al., and Evenson et al. Furthermore, the prevalence of meeting the PA recommendation, 180 min/day of which at least 60 min/day being MVPA, were assessed for the cut-points. Multilevel mixed analysis was used to examine associations of SED and PA with BMI and WC. In accordance with the results, SED and PA intensity estimates differed largely across cut-points (i.e., SED = 22–341 min/day; light PA = 52–257 min/day; moderate PA = 5–18 min/day; vigorous PA = 7–17 min/day; MVPA = 13–35 min/day), and the prevalence of children meeting the PA recommendation varied from 4% to 70%. Associations of SED and PA with BMI or WC varied between the cut-points. Our results indicate that SED and PA estimates in preschool-aged children between studies using these cut-points are poorly comparable. Methods facilitating accelerometer-derived PA estimate comparison between studies are highly warranted.
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| 46. |
- Lindström, L, et al.
(författare)
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Elevated levels of kynurenic acid in the cerebrospinal fluid of male patients with schizophrenia.
- 2005
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Ingår i: Schizophrenia research. - : Elsevier BV. - 0920-9964 .- 1573-2509. ; 80:2-3, s. 315-22
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies have shown that endogenous brain levels of kynurenic acid (KYNA), a glutamate receptor antagonist, are elevated in patients with schizophrenia. Here we analyse KYNA in the cerebrospinal fluid (CSF) from a large cohort, including male healthy controls (n=49) and male patients with schizophrenia (n=90). We found that male patients with schizophrenia had significantly higher levels of CSF KYNA compared to healthy male controls (1.45 nM+/-0.10 vs. 1.06 nM+/-0.06 in the control group). Furthermore, when the patients with schizophrenia were divided into subgroups we found that CSF KYNA levels were significantly elevated in drug-naïve, first episode patients (1.53 nM+/-0.19, n=37) and in patients undergoing treatment with antipsychotic drugs (1.53 nM+/-0.17, n=34) compared to healthy male controls. No elevated CSF KYNA levels were detected in drug-free patients with schizophrenia, i.e. patients previously undergoing antipsychotic medications but drug-free at time of sampling (1.16 nM+/-0.10, n=19). Present results confirm that CSF KYNA concentration is elevated in patients with schizophrenia and are consistent with the hypothesis that KYNA contributes to the pathophysiology of the disease.
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| 47. |
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| 48. |
- Nilsson Ekdahl, Kristina, et al.
(författare)
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Blood protein-polymer adsorption fingerprinting: Implications for understanding hemoocompatibility and for biomaterial design.
- 2011
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Ingår i: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 97A:1, s. 74-84
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to create polymeric materials with known properties to study the preconditions for complement activation. Initially, 22 polymers were screened for complement activating capacity. Based on these results, six polymers (P1-P6) were characterized regarding physico-chemical parameters, for example, composition, surface area, pore size, and protein adsorption from human EDTA-plasma. P2, P4, and reference particles of polystyrene and polyvinyl chloride, were hydrophobic, bound low levels of protein and were poor complement activators. Their accessible surface was limited to protein adsorption in that they had pore diameters smaller than most plasma proteins. P1 and P3 were negatively charged and adsorbed IgG and C1q. A 10-fold difference in complement activation was attributed to the fact that P3 but not P1 bound high amounts of C1-inhibitor. The hydrophobic P5 and P6 were low complement activators. They selectively bound apolipoproteins Al and AIV (and vitronectin), which probably limited the binding of complement activators to the surface. We demonstrate the usefulness of the modus operandi to use a high-throughput procedure to synthesize a great number of novel substances, assay their physico-chemical properties with the aim to study the relationship between the initial protein coat on a surface and subsequent biological events. Data obtained from the six polymers characterized here, suggest that a complement-resistant surface should be hydrophobic, uncharged, and have a small available surface, accomplished by nanostructured topography. Additional attenuation of complement can be achieved by selective enrichment of inert proteins and inhibitors.
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| 49. |
- Nilsson, Per H., et al.
(författare)
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The creation of an antithrombotic surface by apyrase immobilization
- 2010
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Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 31:16, s. 4484-4491
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Tidskriftsartikel (refereegranskat)abstract
- Blood incompatibility reactions caused by surfaces often involve platelet activation and subsequent platelet-initiated activation of the coagulation and complement cascades. The goal of this study was to immobilize apyrase on a biomaterial surface in order to develop an enzymatically active surface that would have the capacity to inhibit platelet activation by degrading ADP. We were able to immobilize apyrase on a polystyrene surface with preservation of the enzymatic activity. We then analyzed the hemocompatibility of the apyrase surface and of control surfaces by incubation with platelet-rich plasma (PRP) or whole blood. Monitoring of markers of platelet, coagulation, and complement activation and staining of the surfaces revealed decreased levels of platelet and coagulation activation parameters on the apyrase surface. The formation of antithrombin-thrombin and antithrombin-factor XIa complexes and the extent of platelet consumption were significantly lower on the apyrase surface than on any of the control surfaces. No significant differences were seen in complement activation (C3a levels). Staining of the apyrase surface revealed low platelet adherence and no formation of granulocyte platelet complexes. These results demonstrate that it is possible to create an antithrombotic surface targeting the ADP amplification of platelet activation by immobilizing apyrase.
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