| 1. |
- Bach, Anders, et al.
(författare)
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Design and synthesis of highly potent and plasma-stable dimeric inhibitors of the PSD-95-NMDA receptor interaction
- 2009
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Ingår i: Angewandte Chemie International Edition. - : Wiley-VCH. - 1433-7851 .- 1521-3773. ; 48:51, s. 9685-9689
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Tidskriftsartikel (refereegranskat)abstract
- On the double: Dimerization of monomeric peptide ligands towards the PDZ domains of the protein PSD-95 (postsynaptic density 95) leads to potent inhibitors of protein-protein interactions with stability in blood plasma. Optimization of the length of the polyethylene glycol linker results in unprecedented affinity for inhibitors of the PDZ1-2 domain.
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| 2. |
- Ahadi, Aylin, et al.
(författare)
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Simulation of Nanoindentation Response of Empty and Filled Viral Capsids
- 2009
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Ingår i: DCE Technical Memorandum. - 1901-7278. ; 11
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Konferensbidrag (refereegranskat)abstract
- The nanoindentation response of empty and filled viral capsids is modelled using three dimensional finite element analysis. Simulation with two different geometries, spherical and icosahedral, are performed using the finite element code Abaqus. The capsids are modeled as non-linear Hookean elastic and both small and large deformation analysis is performed. Force-indentation curves for three different viral capsids are directly compared to experimental data and the Young’s modulus is determined by calibrating the force-indentation curve to data from atomic force microscopy (AFM) experiments. Predictions are made for two additional viral capsids. The results from the simulation showed a good agreement with AFM data, see [1].
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| 3. |
- Balslev, Soren, et al.
(författare)
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Microfluidic dye laser with compact, low-cost liquid dye dispenser
- 2005
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Ingår i: Micro Total Analysis Systems 2004. - 0854048960 ; , s. 375-377
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Konferensbidrag (refereegranskat)abstract
- We present a compact system consisting of a miniaturized fluid dispenser, delivering liquid laser dye to a micro-chip dye laser. This demonstrates the elimination of bulk fluid pumps for a microfluidic system by using a miniaturized, electrically and chemically inert dispenser, capable of delivering very low flow for extended periods of time.
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| 4. |
- Berkenstam, Anders, et al.
(författare)
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The thyroid hormone mimetic compound KB2115 lowers plasma LDL cholesterol and stimulates bile acid synthesis without cardiac effects in humans
- 2008
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 105:2, s. 663-667
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Tidskriftsartikel (refereegranskat)abstract
- Atherosclerotic cardiovascular disease is a major problem despite the availability of drugs that influence major risk factors. New treatments are needed, and there is growing interest in therapies that may have multiple actions. Thyroid hormone modulates several cardiovascular risk factors and delays atherosclerosis progression in humans. However, use of thyroid hormone is limited by side effects, especially in the heart. To overcome this limitation, pharmacologically selective thyromimetics that mimic metabolic effects of thyroid hormone and bypass side effects are under development. In animal models, such thyromimetics have been shown to stimulate cholesterol elimination through LDL and HDL pathways and decrease body weight without eliciting side effects. We report here studies on a selective thyromimetic [KB2115, (3-[[3,5-dibromo-4- [4-hydroxy-3-(1-methylethyl)-phenoxy]-phenyl]-amino]-3-oxopropanoic acid)] in humans. In moderately overweight and hypercholesterolemic subjects KB2115 was found to be safe and well tolerated and elicited up to a 40% lowering of total and LDL cholesterol after 14 days of treatment. Bile acid synthesis was stimulated without evidence of increased cholesterol production, indicating that KB2115 induced net cholesterol excretion. KB2115 did not provoke detectable effects on the heart, suggesting that the pharmacological selectivity observed in animal models translates to humans. Thus, selective thyromimetics deserve further study as agents to treat dyslipidemia and other risk factors for atherosclerosis. © 2007 by The National Academy of Sciences of the USA.
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| 5. |
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| 6. |
- Gülfe, Anders, et al.
(författare)
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Six and 12 Weeks Treatment Response Predicts Continuation of Tumor Necrosis Factor Blockade in Rheumatoid Arthritis: An Observational Cohort Study from Southern Sweden.
- 2009
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Ingår i: Journal of Rheumatology. - : The Journal of Rheumatology. - 0315-162X .- 1499-2752. ; 36, s. 517-521
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate if treatment response predicts continuation of anti-tumor necrosis factor (TNF) treatment in patients with rheumatoid arthritis (RA). METHODS: We investigated if treatment response and/or achieving a certain activity state at 6 weeks or 3 months predicts continuation of treatment in an observational cohort of 1789 anti-TNF-naive patients with established RA disease from southern Sweden. RESULTS: Response to treatment at 6 weeks at overall/American College of Rheumatology (ACR20) or good/major level (except ACR70) significantly predicted drug continuation. Response according to all criteria sets at overall/ACR20 and at good/major/ACR70 level predicted drug continuation at 3 months, as did achieving low disease activity at 3 months irrespective of activity index applied. Remaining in a high disease activity state predicted drug discontinuation at both timepoints and according to all criteria sets. CONCLUSION: Response criteria may be useful aids in deciding on continuation of TNF blockade in RA as early as after 6 weeks of treatment. The various criteria sets perform similarly.
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| 7. |
- Hallberg, Håkan, et al.
(författare)
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Modeling of Continuous Dynamic Recrystallization in Aluminum
- 2009
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Ingår i: DCE Technical Memorandum No. 11. - 1901-7278. ; 11, s. 59-62
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Konferensbidrag (refereegranskat)abstract
- A constitutive model is presented, considering grain size refinement through continuous dynamic recrystallization together with an evolving dislocation density. The grain refinement is allowed to influence both the evolution of the dislocation density and the rate dependence of the material. The model is calibrated against experimental data on aluminum and numerical simulations of equal channel angular pressing (ECAP) material processing illustrates the capabilities of the model.
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| 8. |
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| 9. |
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| 10. |
- Karlsson, JA, et al.
(författare)
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Treatment response to a second or third TNF-inhibitor in RA: results from the South Swedish Arthritis Treatment Group Register.
- 2008
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Ingår i: Rheumatology. - : Oxford University Press (OUP). - 1462-0332 .- 1462-0324. ; 47:4, s. 507-513
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Tidskriftsartikel (refereegranskat)abstract
- Objectives. To study treatment response rates of RA patients undergoing second- and third-line anti-TNF therapy and to identify baseline predictors of response to second-line treatment. Methods. RA patients monitored in a prospective, observational study, having switched anti-TNF therapy once (first-time switchers, n = 337) or twice (second-time switchers, n = 36)-i.e. following failures with one antibody- and one receptor-type agent-between March 1999 and December 2006, were studied. Treatment responses at 3 months were assessed by the ACR and European League Against Rheumatism (EULAR) response criteria. Predictive potentials for response to second-line treatment of demographics, baseline disease activity measures, disease and treatment characteristics were analysed using logistic regression. Results. ACR20 response was met by 51% of first-time and 35% of second-time switchers. Corresponding ACR50 rates were 27 and 18%; EULAR overall rates (EULAR good or moderate response) 71 and 58%; EULAR good rates 25 and 9% and 28-joint disease activity score (DAS28) remission rates 16 and 6%. Identified baseline predictors of response to second-line treatment were lower age and HAQ scores, elevated DAS28 values and having ceased the former anti-TNF treatment due to adverse events rather than inefficacy. No variable was predictive for all examined response criteria. Conclusions. Response rates of first-time anti-TNF switchers are somewhat below those of anti-TNF naïve RA patients, while the markedly inferior response rates of second-time switchers suggest other therapeutic options to be considered in this situation. Identified baseline predictors of response may be useful indicators to second-line anti-TNF therapy, but vary depending on the response criteria set studied.
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| 11. |
- Kjaergaard, Benedict, et al.
(författare)
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A porcine model of massive, totally occlusive, pulmonary embolism
- 2009
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Ingår i: Thrombosis Research. - : Elsevier BV. - 0049-3848 .- 1879-2472. ; 124:2, s. 226-9
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: A reliable, animal model of massive, totally occlusive, pulmonary embolism (PE) is lacking. OBJECTIVES: To design an animal model of totally occlusive PE and to challenge the model by a plasminogen activator. METHODS: In eight anaesthetized pigs (approximately 90 kg) a massive preformed autologous thrombus was injected into the caval vein. One animal was autopsied to assess the extent of injected clot, whereas in the other animals extracorporeal life support (ECLS) was initiated and continued for three hours. These animals received 100 mg rt-PA. Blood gases, coagulation tests, creatine kinase (CK), lactate dehydrogenase (LDH), end-tidal CO2, systemic and pulmonary artery blood pressures and flow were registered. RESULTS: All animals went into circulatory arrest within 2 minutes after injection of the thrombus. In the animal where ECLS was not started, autopsy relieved a totally occlusive embolus of the pulmonary artery. The ECLS maintained a systemic blood flow of 6-8 L/min with adequate oxygenation and CO2-removal. However, lactate increased and base-excess became negative. Ddimer increased, fibrinogen decreased, and CK and LDH increased. All seven animals were weaned from ECLS. Despite the rt-PA treatment, the animals had at that time low end tidal CO2/PaCO2 ratio and increased mean pulmonary arterial pressure, suggesting a significant amount of embolic material remaining in the pulmonary artery. CONCLUSION: This model of massive, totally occlusive, pulmonary embolism mimics well fatal PE seen in the clinic, and has the potential for use in testing of new therapeutic interventions.
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| 12. |
- Kristensen, Anders Raastrup, et al.
(författare)
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Symptoms of organization
- 2008
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Ingår i: Ephemera: Theory and Politics in Organization. - 1473-2866. ; 8:1, s. 1-1
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 13. |
- Kristensen, Karl, et al.
(författare)
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Cystatin C, beta-2-microglobulin and beta-trace protein in pre-eclampsia
- 2007
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Ingår i: Acta Obstetricia et Gynecologica Scandinavica. - : Wiley. - 1600-0412 .- 0001-6349. ; 86:8, s. 921-926
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Tidskriftsartikel (refereegranskat)abstract
- Background. An altered renal function is an essential component of the patho-physiology of pre-eclampsia. The plasma levels of low molecular mass proteins, e. g. beta-trace protein, beta-2-microglobulin and cystatin C, are increased in the third trimester of normal pregnancy. The plasma levels of cystatin C and beta-2-microglobulin are further increased in preeclampsia, and the cystatin C level has been reported to be a reliable marker for the disease. The aim of this investigation was to study the plasma levels of beta-trace protein, beta-2-microglobulin and cystatin C in pre-eclampsia, and to determine the diagnostic performance of these proteins compared to that of urate and creatinine. Methods. A case-control study of 57 women diagnosed with pre-eclampsia, and 218 healthy women with uncomplicated singleton pregnancies in the third trimester. Women in the catchment area of Lund, Sweden, were included during an 18-month period from October 2003 to April 2005. Venous blood samples were drawn upon inclusion when diagnosis was made. The maternal plasma concentrations of the 3 proteins were analysed by automated particle-enhanced immunoturbidimetric assays. Results. The plasma levels of the 3 proteins were significantly higher in the third trimester of pre-eclamptic patients compared to healthy pregnant women in the third trimester. The upper reference limits ( parametric 97.5 percentile) were 2.57 mg/l for beta-2-microglobulin, 0.72 mg/l for beta-trace protein and 1.37 mg/l for cystatin C. ROC analysis showed similar diagnostic performance for the 3 proteins, with b-trace protein displaying the best diagnostic performance of all the analytes. Conclusions. In this study, the maternal plasma levels of beta 2-microglobulin, beta-trace protein and cystatin C were all significantly elevated in pre-eclampsia compared to those of healthy pregnant women, and displayed similar diagnostic performance for diagnosing pre-eclampsia. The results indicate that low molecular mass proteins are useful as markers of renal impairment in pre-eclampsia.
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| 14. |
- Kristensen, Karl, et al.
(författare)
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Increased plasma levels of ss(2)-microglobulin, cystatin C and ss-trace protein in term pregnancy are not due to utero-placental production.
- 2008
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Ingår i: Scandinavian Journal of Clinical & Laboratory Investigation. - : Informa UK Limited. - 1502-7686 .- 0036-5513. ; 68, s. 649-653
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Tidskriftsartikel (refereegranskat)abstract
- Objective . To study concentration gradients of the low molecular mass proteins, ss(2)-microglobulin, cystatin C and ss-trace protein, between the uterine and ante-cubital veins, the umbilical artery and vein and in the amniotic fluid compartment. Material and methods. The study comprised 27 healthy women with uncomplicated pregnancies undergoing caesarean section at term. Samples were collected simultaneously and paired t-tests were used to compare mean plasma concentrations. Results . There was no significant concentration gradient in the plasma levels of ss(2)-microglobulin, cystatin C or ss-trace protein between the uterine and antecubital veins. There were no correlations between the protein levels in the compartments. Conclusion . The utero-placental unit does not contribute significantly to the maternal levels of ss(2)-microglobulin, cystatin C and ss-trace protein in normal pregnancy, and the proteins are not likely to be transferred across the placental barrier.
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| 15. |
- Kristensen, Karl, et al.
(författare)
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Serum Amyloid A Protein and C-Reactive Protein in Normal Pregnancy and Preeclampsia.
- 2009
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Ingår i: Gynecologic and Obstetric Investigation. - : S. Karger AG. - 1423-002X .- 0378-7346. ; 67:4, s. 275-280
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Tidskriftsartikel (refereegranskat)abstract
- Aims: To study plasma levels of serum amyloid A protein and C-reactive protein in pregnant women with and without preeclampsia and non-pregnant women. Plasma levels of haptoglobin, orosomucoid and ceruloplasmin were also analyzed. Methods: The study included 295 women with uncomplicated pregnancies, 57 women diagnosed with preeclampsia, and 58 healthy non-pregnant women. Plasma concentrations of acute phase proteins were analyzed by particle-enhanced immunoassays. Non-parametric Kruskal-Wallis and Mann-Whitney U tests were used to test differences between the groups. Results: Plasma levels of C-reactive protein and ceruloplasmin were increased in pregnant women with and without preeclampsia compared to non-pregnant women. Plasma levels of serum amyloid A protein and C-reactive protein were not elevated in women with preeclampsia compared to women with normal pregnancy. Conclusion: The description of preeclampsia as a systemic inflammatory state was not reflected in the plasma levels of serum amyloid A protein and C-reactive protein.
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| 16. |
- Kristensen, Karl, et al.
(författare)
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Temporal changes of the plasma levels of cystatin C, beta-trace protein, beta(2)-microglobulin, urate and creatinine during pregnancy indicate continuous alterations in the renal filtration process
- 2007
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Ingår i: Scandinavian Journal of Clinical & Laboratory Investigation. - : Informa UK Limited. - 1502-7686 .- 0036-5513. ; 67:6, s. 612-618
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To determine the plasma levels of the renal functional markers creatinine, urate, cystatin C, beta(2)-microglobulin and beta-trace protein in samples from the first, second, early third and late third trimesters of 398 healthy women with uncomplicated singleton pregnancies. Material and methods. Plasma samples from 58 healthy non-pregnant women served as controls. The creatinine levels were significantly lower at all time-points in pregnancy, whereas the urate levels were lower during the first and second trimesters but increased in the late third trimester. The cystatin C, beta(2)-microglobulin and beta-trace protein levels displayed similar changes with increased levels in the third trimester but unaltered levels during the first and second trimesters. Results. The results indicate an increased filtration of low-molecular weight molecules during pregnancy, particularly during the first and second trimesters, whereas filtration of 10-30 kDa molecules is decreased in the third but unaltered in the first and second trimesters. The levels of albumin and alpha(2)-macroglobulin were measured in the same samples. Conclusions. The albumin levels decreased in the second and third trimesters, whereas the levels of alpha(2)-macroglobulin were unchanged, which is compatible with a virtually unaltered transfer of alpha(2)-macroglobulin between the intra-and extravascular space during pregnancy and a significantly increased extravascular fraction of albumin.
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| 17. |
- Kristensen, Lars Erik, et al.
(författare)
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Efficacy and tolerability of anti-TNF therapy in psoriatic arthritis patients: Results from the South Swedish Arthritis Treatment Group Register.
- 2008
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Ingår i: Annals of the Rheumatic Diseases. - : BMJ. - 1468-2060 .- 0003-4967. ; 67, s. 364-369
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Tidskriftsartikel (refereegranskat)abstract
- Background: The use of tumour necrosis factor (TNF) blocking agents in psoriatic arthritis (PsA) is increasing, and the SSATG register has followed patients with PsA for more than 5 years. The aim of the present work therefore was to present efficacy and tolerability data of TNF-blocking agents on PsA in clinical practice, and to study potential predictors for drug survival (the length of time a patient continues to take a particular drug). Materials and methods: Patients (n = 261) with active PsA, starting anti-TNF therapy for the first time in southern Sweden, were included. Basal characteristics, disease activity measures, and termination reason for blockers were prospectively collected during the period April 1999 to September 2006. Cox proportional hazard models were used to investigate predictors for treatment termination. Results: Overall, response rates at 3–12 months for global visual analogue scale (VASglobal50) and pain VAS (VASpain50) were about 50%, whereas response rates for European League Against Rheumatism (EULAR) scoring "overall" and EULAR "good" were around 75% and 55%, respectively. Concomitant methotrexate (MTX) (hazard ratio (HR) 0.64, 95% CI 0.39–0.95, p = 0.03), etanercept (HR 0.49, 95% CI 0.28–0.86, p = 0.01), and high C-reactive protein (CRP) levels (HR 0.77, 95% CI 0.61–0.97, p = 0.03) at treatment initiation were associated with better overall drug survival. The improved drug survival of concomitant MTX appeared to be related to significantly fewer dropouts because of adverse events (HR = 0.24 (0.11–0.52), p<0.01). The blockers were well tolerated with a rate of serious adverse events of 5–6% per year. No unexpected serious adverse events were observed. Conclusion: Concomitant MTX and high CRP levels are associated with treatment continuation of anti-TNF therapy in patients with PsA regardless of joint distribution. The positive effect of MTX was primarily linked to fewer dropouts because of adverse events.
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| 18. |
- Kristensen, Lars Erik, et al.
(författare)
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Predictors of response to anti-TNF therapy according to ACR and EULAR criteria in patients with established RA: results from the South Swedish Arthritis Treatment Group Register.
- 2008
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Ingår i: Rheumatology (Oxford, England). - : Oxford University Press (OUP). - 1462-0332 .- 1462-0324. ; 47:4, s. 495-499
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To identify factors predicting response to first TNF blocking treatment course in patients with established RA with a special focus on gender differences. METHODS: Patients with active RA initiating their first treatment course of TNF-blocking therapy were enrolled. The study period was March 1999 through September 2006. The prospective protocol included information on demographics, clinical characteristics of patients and response measures. Fulfilment of ACR 50-70% improvement and European League Against Rheumatism (EULAR) good response or remission [28-joint disease activity score (DAS28) <2.6] at 3 months were chosen as primary outcome measures. Potential predictors of responses were identified using multivariate binary logistic regression models. RESULTS: In total, 1565 patients were included in the study. Gender did not influence treatment response. Consistently, concomitant methotrexate (MTX) was significantly associated with EULAR remission, EULAR good response, ACR50 response and ACR70 response with odds ratios (ORs) 1.97, 2.13, 2.10 and 1.75, respectively. Concurrent treatment with other DMARDs was also significantly associated with EULAR remission, EULAR good response and ACR50 response (OR: 1.96, 2.24 and 1.94, respectively). Likewise, low HAQ at baseline consistently predicted good clinical outcome. Disease activity at baseline was directly associated with favourable response when measured by ACR50 and ACR70 (OR: 1.59 and 1.60, respectively), whereas DAS28 score at baseline was inversely associated with EULAR remission (OR: 0.78). CONCLUSIONS: In this observational study of patients with established RA, gender did not predict response to anti-TNF therapy, whereas treatment with concomitant DMARDs, especially MTX and low disability were associated with good response. Choice of outcome measures may influence the predictive value of baseline features.
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| 19. |
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| 20. |
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| 21. |
- Moller-Kristensen, Mette, et al.
(författare)
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Cooperation between MASP-1 and MASP-2 in the generation of C3 convertase through the MBL pathway
- 2007
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Ingår i: International Immunology. - : Oxford University Press (OUP). - 1460-2377 .- 0953-8178. ; 19:2, s. 141-149
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Tidskriftsartikel (refereegranskat)abstract
- The complement system is an important part of the innate immune system. Three pathways, the classical, the alternative and the lectin pathway, lead to the cleavage of complement factor C3, a central event in the activation of the complement system. We investigated the deposition of C3b (solid-phase C3 activation product) on a mannan-coated surface at high concentration of human serum (17%). At these conditions, mannan-binding lectin (MBL) promoted the activation of C3 through the combined action of MBL-associated serine protease (MASP)-1 and MASP-2 without appreciable involvement of the alternative pathway. In serum depleted of MASP-1, MASP-2 and MASP-3, we observed synergetic effect of reconstitution with MASP-1 and MASP-2. This was inhibited by MASP-3. No C3b deposition was observed with C2- or C4-depleted serum. Depletion of factor B had no effect on the MBL-MASP-promoted C3b deposition. Our results demonstrate a function of the orphan protease MASP-1 by providing evidence that this enzyme collaborates with MASP-2 in the generation of C3 convertase, a process observable at high serum concentration, but not at low serum concentration.
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| 22. |
- Mosén, Kristina, et al.
(författare)
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The apparent plasticizing effect of polyethylene glycol (PEG) on the crystallinity of spray dried lactose/PEG composites
- 2006
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Ingår i: European Journal of Pharmaceutics and Biopharmaceutics. - : Elsevier BV. - 0939-6411. ; 64:2, s. 206-211
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Tidskriftsartikel (refereegranskat)abstract
- Aqueous solutions of lactose and polyethylene glycol (PEG) were spray dried in a Buchi Model 191 spray dryer with the aim to investigate the effect of PEG on the crystallinity of the composite. A PEG concentration of 10.7% by weight of solids was studied for PEG 200, 600, 1500, 4000 and 8000. For PEG 200 and 4000 additional concentrations from 1.5-19.3% to 1.5-32.4%, respectively, were investigated. The spray dried composites were analysed with X-ray powder diffraction and modulating differential scanning calorimetry. The crystallinity of lactose in the composites varied from 0% to 60%, dependent on the molecular weight and concentration of PEG. Apparently, lactose crystallinity is promoted by low molecular weight and high concentration of the PEG. PEG did not affect the lactose glass transition temperature. It is suggested that lactose and PEG are solidified separately during spray drying and that partial crystallization of lactose is associated with effects of PEG on the rate of drying.
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| 23. |
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| 24. |
- Persson, Fredrik, et al.
(författare)
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Polarization anisotropy of DNA in nanochannels
- 2008
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Ingår i: ; , s. 668-670
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Konferensbidrag (refereegranskat)abstract
- The local alignment of DNA stretched in nanofluidic channels is measured using polarization sensitive detection. With increased degree of stretching the polarization anisotropy increases both in the deGennes and the Odijk regime. The technique is expected to find use in studies of, for example, local conformational changes in polymer physics in confined spaces, studies of protein-DNA interactions and compactation of DNA.
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| 25. |
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| 26. |
- Reisner, Walter, et al.
(författare)
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Directed self-organization of single DNA molecules in a nanoslit via embedded nanopit arrays
- 2009
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 106:1, s. 79-84
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Tidskriftsartikel (refereegranskat)abstract
- We show that arrays of nanopit structures etched in a nanoslit can control the positioning and conformation of single DNA molecules in nanofluidic devices. By adjusting the spacing, organization and placement of the nanopits it is possible to immobilize DNA at predetermined regions of a device without additional chemical modification and achieve a high degree of control over local DNA conformation. DNA can be extended between two nanopits and in closely spaced arrays will self-assemble into "connect-the-dots" conformations consisting of locally pinned segments joined by fluctuating linkers. These results have broad implications for nanotechnology fields that require methods for the nanoscale positioning and manipulation of DNA.
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| 27. |
- Reisner, Walter, et al.
(författare)
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Nanoconfinement-enhanced conformational response of single DNA molecules to changes in ionic environment
- 2007
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Ingår i: Physical Review Letters. - 1079-7114. ; 99:5
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Tidskriftsartikel (refereegranskat)abstract
- We show that the ionic environment plays a critical role in determining the configurational properties of DNA confined in silica nanochannels. The extension of DNA in the nanochannels increases as the ionic strength is reduced, almost tripling over two decades in ionic strength for channels around 100x100 nm in dimension. Surprisingly, we find that the variation of the persistence length alone with ionic strength is not enough to explain our results. The effect is due mainly to increasing self-avoidance created by the reduced screening of electrostatic interactions at low ionic strength. To quantify the increase in self-avoidance, we introduce a new parameter into the de Gennes theory: an effective DNA width that gives the increase in the excluded volume due to electrostatic repulsion.
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| 28. |
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