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- Bergkvist Sylvan, Sara, 1977-
(författare)
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Numerical studies of spin chains and cold atoms in optical lattices
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An important, but also difficult, research field in condensed matter physics is that of strongly correlated systems. This thesis considers two topics in this field. The first topic is disorder and frustration in spin models. The introduction of disorder into quantum spin chains creates a complex problem. The ground state of the random-bond spin-1 Heisenberg chain is studied by means of stochastic series expansion quantum Monte Carlo simulation, applying the concept of directed loops. It is found that this system undergoes a phase transition to the random-singlet phase if the bond disorder is strong enough. Further a frustrated spin system is investigated. The frustration is introduced by having spins positioned on a triangular lattice. Performing a quantum Monte Carlo simulation for such a frustrated lattice leads to the occurrence of the infamous sign problem. This problem is investigated and it is shown that it is possible to use a meron cluster approach to reduce its effect for some specific models. The second topic concerns atomic condensates in optical lattices. A system of trapped bosonic atoms in such a lattice is described by a Bose-Hubbard model with an external confining potential. Using quantum Monte Carlo simulations it is demonstrated that the local density approximation that relates the observables of the unconfined and the confined models yields quantitatively correct results in most of the interesting parameter range of the model. Further, the same model with the addition that the atoms carry spin-1 is analyzed using density matrix renormalization group calculations. The anticipated phase diagram, with Mott insulating regions of dimerized spin-1 chains for odd particle density, and on-site singlets for even density is confirmed. Also an ultracold gas of bosonic atoms in an anisotropic two dimensional optical lattice is studied. It is found that if the system is finite in one direction it exhibits a quantum phase transition. The Monte Carlo simulations performed show that the transition is of Kosterlitz-Thouless type.
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| 2. |
- Brorsson, Camilla, et al.
(författare)
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Adrenal response after trauma is affected by time after trauma and sedative/analgesic drugs
- 2014
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Ingår i: Injury. - : Elsevier. - 0020-1383 .- 1879-0267. ; 45:8, s. 1149-1155
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The adrenal response in critically ill patients, including trauma victims, has been debated over the last decade. The aim of this study was to assess the early adrenal response after trauma. METHODS: Prospective, observational study of 50 trauma patients admitted to a level-1-trauma centre. Serum and saliva cortisol were followed from the accident site up to five days after trauma. Corticosteroid binding globulin (CBG), dehydroepiandrosterone (DHEA) and sulphated dehydroepiandrosterone (DHEAS) were obtained twice during the first five days after trauma. The effect of time and associations between cortisol levels and; severity of trauma, infusion of sedative/analgesic drugs, cardiovascular dysfunction and other adrenocorticotropic hormone (ACTH) dependent hormones (DHEA/DHEAS) were studied. RESULTS: There was a significant decrease over time in serum cortisol both during the initial 24 h, and from the 2nd to the 5th morning after trauma. A significant decrease over time was also observed in calculated free cortisol, DHEA, and DHEAS. No significant association was found between an injury severity score >/= 16 (severe injury) and a low (< 200 nmol/L) serum cortisol at any time during the study period. The odds for a serum cortisol < 200 nmol/L was eight times higher in patients with continuous infusion of sedative/analgesic drugs compared to patients with no continuous infusion of sedative/analgesic drugs. CONCLUSION: Total serum cortisol, calculated free cortisol, DHEA and DHEAS decreased significantly over time after trauma. Continuous infusion of sedative/analgesic drugs was independently associated with serum cortisol < 200 nmol/L.
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| 3. |
- Brorsson, Camilla, 1967-
(författare)
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Trauma - logistics and stress response
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Trauma is a major cause of death and disability. Adverse events, such as prolonged prehospital time, hypoxia, hypotension and/or hyperventilation have been reported to correlate to poor outcome.Adequate cortisol levels are essential for survival after major trauma. In hypotensive critically ill patients, lack of sufficient amount of cortisol can be suspected, and a concept of critical illness related corticosteroid insufficiency has been proposed. Corticosteroid therapy has many adverse effects in critically ill patients and should only be given if life-saving. Correct measurement of serum cortisol levels is important but difficult in critically ill patients with capillary leakage. Estimation of the free and biologically active cortisol is preferable. In serum less than 10% of cortisol is free and biologically active and not possible to measure with routine laboratory methods. Salivary cortisol can be used as a surrogate for free cortisol, but salivary production is reduced in critically ill patients. Liver resection could reduce cortisol levels due to substrate deficiency.Aims: 1. Evaluate the occurrence of early adverse events in patients with traumatic brain injury and relate them to outcome. 2. Assess cortisol levels over time after trauma and correlate to severity of trauma, sedative/analgesic drugs and cardiovascular function. 3. Evaluate if saliva stimulation could be performed without interfering with salivary cortisol levels. 4. Assess cortisol levels over time after liver resection in comparison to other major surgery.Results: There was no significant correlation between prehospital time ³60 minutes, hypoxia (saturation <95%), hypotension (systolic blood pressure <90 mmHg), or hyperventilation (ETCO2 <4.5 kPa) and a poor outcome (Glasgow Outcome Scale 1-3) in patients with traumatic brain injury. Cortisol levels decreased significantly over time after trauma, but there was no correlation between low (<200 nmol/L) serum cortisol levels and severity of trauma.Infusion of sedative/analgesic drugs was the strongest predictor for a low (<200 nmol/L) serum cortisol. The odds ratio for low serum cortisol levels (<200 nmol/L) was 8.0 for patients receiving continuous infusion of sedative/analgesic drugs. There was no significant difference between unstimulated and stimulated salivary cortisol levels (p=0.06) in healthy volunteers. Liver resection was not associated with significantly lower cortisol levels compared to other major surgery.Conclusion: There was no significant correlation between early adverse events and outcome in patients with traumatic brain injury. Cortisol levels decreased significantly over time in trauma patients. Low cortisol levels (<200 nmol/L) were significantly correlated to continuous infusion of sedative/analgesic drugs. Saliva stimulation could be performed without interfering with salivary cortisol levels. Liver resection was not associated with low cortisol levels compared to other major surgery.
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| 4. |
- Herrmann, Björn, et al.
(författare)
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Prevalence Trends of the New Variant of Chlamydia trachomatis in Four Counties of Sweden in 2007-2011
- 2012
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Ingår i: Sexually Transmitted Diseases. - : Lippincott Williams & Wilkins. - 0148-5717 .- 1537-4521. ; 39:8, s. 648-650
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Tidskriftsartikel (refereegranskat)abstract
- A new variant of Chlamydia trachomatis (nvCT) was discovered in Sweden in 2006, and it could not be detected by diagnostic systems from Abbott and Roche, whereas the third system used, from Becton Dickinson (BD), detects nvCT. We analyzed 3648 samples from 2 counties that used Roche and 2 counties that used BD methods from 2007 to 2011. After implementation of a Roche method that detects nvCT, its proportion has decreased and converged in the 4 counties but are still at different levels in Roche and BD counties. Future studies are needed to see if nvCT will decline further.
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| 5. |
- Klint, Markus, et al.
(författare)
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Prevalence trends in Sweden for the new variant of Chlamydia trachomatis
- 2011
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Ingår i: Clinical Microbiology and Infection. - : Elsevier. - 1198-743X .- 1469-0691. ; 17:5, s. 683-689
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Tidskriftsartikel (refereegranskat)abstract
- In 2006, a new variant of Chlamydia trachomatis (nvCT) was discovered in Sweden that was not detectable with Abbott m2000 (Abbott) and Amplicor/COBAS Amplicor/TaqMan48 (Roche). The proportion of nvCT was 20-64% of the detected Chlamydia cases in counties using Abbott/Roche test systems. Although the ProbeTec system from Becton Dickinson (BD) could detect nvCT, the proportion of nvCT in counties using BD was 7-19%. The objective of the current study was to follow the nvCT proportions from 2007 to 2009 in two counties that used Roche and had introduced test systems able to detect nvCT in late 2006. The nvCT was also followed in two counties that used BD, and in all four counties the effect of nvCT on the serotype distribution of C. trachomatis wild-type strains was analysed. A total of 2576 specimens positive for C. trachomatis were collected in the four counties at three time points, and analysed for nvCT and serotype E. The proportion of nvCT declined significantly in the two counties using Roche, from 65% and 48% in 2007 to 24% for both counties in 2009 (p < 0.001). The nvCT proportion increased in Norrbotten county, which used BD, from 9% in 2007 to 19% in 2009 (p 0.03). In Uppsala county, which also used BD but was surrounded by counties using detection systems from Roche, the proportion of nvCT declined from 24% in 2007 to 18% in 2009 (p < 0.03). No major difference in the level of serotype E was seen. The proportion of nvCT seems to rapidly converge in the Swedish counties after the selective diagnostic advantage for nvCT has been lost in the Abbott/Roche counties.
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| 6. |
- Mattsson, Agnes, et al.
(författare)
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Idelalisib (PI3Kδ inhibitor) therapy for patients with relapsed/refractory chronic lymphocytic leukemia : A Swedish nation-wide real-world report on consecutively identified patients
- 2023
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Ingår i: European Journal of Haematology. - : John Wiley & Sons. - 0902-4441 .- 1600-0609. ; 111:5, s. 715-721
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Tidskriftsartikel (refereegranskat)abstract
- ObjectivesWe examined the efficacy and toxicity of the PI3Kδ inhibitor idelalisib in combination with rituximab salvage therapy in consecutively identified Swedish patients with chronic lymphocytic leukemia (CLL).Methods and ResultsThirty-seven patients with relapsed/refractory disease were included. The median number of prior lines of therapy was 3 (range 1–11); the median age was 69 years (range 50–89); 22% had Cumulative Illness Rating Scale (CIRS) >6 and 51% had del(17p)/TP53 mutation. The overall response rate was 65% (all but one was partial response [PR]). The median duration of therapy was 9.8 months (range 0.9–44.8). The median progression-free survival was 16.4 months (95% CI: 10.4–26.3) and median overall survival had not been reached (75% remained alive at 24 months of follow-up). The most common reason for cessation of therapy was colitis (n = 8, of which seven patients experienced grade ≥3 colitis). The most common serious adverse event was grade ≥3 infection, which occurred in 24 patients (65%).ConclusionsOur real-world results suggest that idelalisib is an effective and relatively safe treatment for patients with advanced-stage CLL when no other therapies exist. Alternative dosing regimens and new PI3K inhibitors should be explored, particularly in patients who are double-refractory to inhibitors of BTK and Bcl-2.
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| 7. |
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| 8. |
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| 9. |
- Sylvan, Anders, 1952-
(författare)
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Jejunoileal bypass for morbid obesity : studies of the long-term effects
- 1995
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study was aimed at investigating adverse and beneficial long-term effects of jejunoileal bypass (JIB) sugery in obese patients. The JIB was the first widly used surgical procedure for treatment of morbid obesity. The weight loss was remarkable, but the procedure was declared not appropiate for obesity surgery in the late 1970's. Serious late adverse effects such as liver cirrhosis and malignancies, have been postulated. Unexpectedly few studies have adressed these problems.In the long-term follow-up of 87 uniformly operated patients, several persisting beneficial effects were found. The mean Body Mass Index was 41.5 kg/m2 at the time of operation and 29.7 kg/m2 sixteen years after the operation. Diabetes type II and hyperlipidemia, common in an obese population, was not found in this group. Reversals were performed in 3% of the patients in contrast to 20-30% in many earlier studies. Revisions performed in 8% of the patients due to excessive weight loss could have contributed to the good long-term outcome.Percutaneous liver biopsies from 44 patients taken 14-20 (mean 17) years after JIB revealed normal or fatty liver, a lower degree of histological abnormalities than in 11 biopsies taken at the time of operations 1-14 (mean 6) years postoperatively. Liver cirrhosis seen early in one patient could not be found in the late biopsies.Reduced activity of the fibrinolytic system has been shown to be a new cardiovacular risk factor. In 45 patients studied 14-20 years after JIB, the levels of both plasminogen activator inhibitor type 1 (PAI-1) and tissue plasminogen activator (tPA) were significantly lower than in a control group of 10 morbidly obese patients ( PAI-1: 8.4 vs 32 U/mL, tPA: 7.2 vs 12 pg/L).Bile acids are regarded as cofactors in the carcinogenesis in the colon and experimentally an increased frequency of malignant tumors has been demonstated after JIB in carcinogen-induced rats. In 30 of the operated patients, colonoscopy with biopsy was performed 11-17 yeras after the operation. No evidence for malignant transformation was found as reflected by an abscense of polyp formation, histologic dysplasia or aneuploidia in flow cytometric DNA analysis.Eight hundred and thirty patients from 10 hospitals subjected to JIB were compared to 1660 controls with respect to malignant diagnosis over a 20 years period. No significantly increased risk for colorectal carcinoma could be demonstrated. However the overall risk for malignant disease was increased in the operated patients. The frequency of endometrial carcinoma was significantly elevated up to five years after the operation but was normal after that time.In conclusion the postulated progress of serious adverse effects of JIB such as liver cirrhosis and malignant disease has not been possible to demonstrate. Several beneficial effects such as weight loss and reduction of cardiovascular risk factors have been found a long time after the operation.
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| 10. |
- Sylvan, Sandra Eketorp, et al.
(författare)
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First-line therapy in chronic lymphocytic leukemia : a Swedish nation-wide real-world study on 1053 consecutive patients treated between 2007 and 2013
- 2019
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Ingår i: Haematologica. - : FERRATA STORTI FOUNDATION. - 0390-6078 .- 1592-8721. ; 104:4, s. 797-805
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate long-term outcome following first-line therapy in consecutive chronic lymphocytic leukemia (CLL) patients in a well-defined geographic area: Sweden. All patients diagnosed with CLL (2007-2013) (n=3672) were identified from national registries, screening of patient files identified all (100%) treated first line (n=1053) and for those, an in-depth analysis was performed. End points were overall response rate, progression-free survival (PFS), overall survival (OS), and safety. Median age was 71 years; 53% had Rai stage III-IV and 97% had performance status grade 0-2. Fluorescence in situ hybridization (FISH) was performed in 57% of patients: 15% had del(17p). Chlorambucil + prednisone was used in 39% (5% also received rituximab). Fludarabine+cyclophosphamide+rituximab or fludarabine+cyclophosphamide was used in 43% and bendamustine + rituximab in 6%. Overall response rate was 64%; chlorambucil 43%, fludarabine+cyclophosphamide+rituximab 84%, fludarabine+cyclophosphamide 75% and bendamustine + rituximab 75%. Median PFS and OS was 24 and 58 months, respectively, both were significantly associated (multivariate analysis) with type of treatment, del(17p), performance status, gender, age and geographical region (OS only). Chlorambucil-treated patients had a median PFS and OS of only 9 and 33 months, respectively. Chlorambucil usage declined gradually throughout the study period, but one-third of patients still received chlorambucil + rituximab in 2013. Infections >= grade III were significantly associated with treatment; chlorambucil 19% versus fludarabine+cyclophosphamide+rituximab 30%. Richter transformation occurred in 5.5% of the patients, equally distributed across therapies. This is the largest retrospective, real-world cohort of consecutive first-line treated CLL patients with a complete follow up. In elderly patients, an unmet need for more effective, well-tolerated therapies was identified.
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