| 1. |
- Frostegård, Johan, et al.
(författare)
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Antibodies against Phosphorylcholine among New Guineans Compared to Swedes: An Aspect of the Hygiene/Missing Old Friends Hypothesis.
- 2017
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Ingår i: Immunological investigations. - : Informa UK Limited. - 1532-4311 .- 0882-0139. ; 46:1, s. 59-69
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Tidskriftsartikel (refereegranskat)abstract
- We here study antibodies against phosphorylcholine (anti-PC) which we reported to be inversely associated with atherosclerosis, cardiovascular disease (CVD), and autoimmune conditions. In previous studies, we determined that this inverse association is more pronounced at low levels with high risk and at high levels, with decreased risk. We compare individuals from Kitava, New Guinea (with low risk of these conditions), with Swedish controls.We studied a group of 178 individuals from Kitava (age 20-86), and compared those above age 40 (n = 108) with a group of age- and sex-matched individuals from a population based cohort in Sweden (n = 108). Traditional risk factors for CVD and fatty acids were determined. IgM, IgG, and IgA anti-PC were tested by enzyme-linked immunosorbent assay (ELISA).All anti-PC measures were significantly lower among Swedish controls as compared to Kitavans (p < 0.001), independent of traditional risk factors. Having low levels of anti-PC, defined as below 25th percentile of values among Swedish controls, was associated with this cohort after adjustment for other risk factors (OR 5.7, 95% CI 2.2-14.7 for IgM; OR 31.7, 95% CI 3.9-252 for IgA; and OR 11.1, 95% CI 2.4-51 for IgG).PC is highly exposed on microorganisms and helminths (common on Kitava) exposing much PC which humans and hominids may have been exposed to for millions of years. We propose that low anti-PC levels in the developed world could be a new aspect of the hygiene hypothesis, generating a pro-inflammatory and pro-atherosclerotic state.
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| 2. |
- Chen, Cong, et al.
(författare)
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Distinguishing attosecond electron-electron scattering and screening in transition metals
- 2017
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 114:27, s. E5300-E5307
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Tidskriftsartikel (refereegranskat)abstract
- Electron-electron interactions are the fastest processes in materials, occurring on femtosecond to attosecond timescales, depending on the electronic band structure of the material and the excitation energy. Such interactions can play a dominant role in light-induced processes such as nano-enhanced plasmonics and catalysis, light harvesting, or phase transitions. However, to date it has not been possible to experimentally distinguish fundamental electron interactions such as scattering and screening. Here, we use sequences of attosecond pulses to directly measure electron-electron interactions in different bands of different materials with both simple and complex Fermi surfaces. By extracting the time delays associated with photoemission we show that the lifetime of photoelectrons from the d band of Cu are longer by similar to 100 as compared with those from the same band of Ni. We attribute this to the enhanced electron-electron scattering in the unfilled d band of Ni. Using theoretical modeling, we can extract the contributions of electron-electron scattering and screening in different bands of different materials with both simple and complex Fermi surfaces. Our results also show that screening influences high-energy photoelectrons (approximate to 20 eV) significantly less than low-energy photoelectrons. As a result, high-energy photoelectrons can serve as a direct probe of spin-dependent electron-electron scattering by neglecting screening. This can then be applied to quantifying the contribution of electron interactions and screening to low-energy excitations near the Fermi level. The information derived here provides valuable and unique information for a host of quantum materials.
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| 3. |
- Chen, Zhiwei, et al.
(författare)
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Cross-Device Radio Frequency Fingerprinting Identification Based on Domain Adaptation
- 2024
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Ingår i: IEEE transactions on consumer electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0098-3063 .- 1558-4127. ; 70:1, s. 2391-2400
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Tidskriftsartikel (refereegranskat)abstract
- Radio frequency fingerprinting (RFF) is a lightweight authentication technology for resource-limited terminal nodes by exploiting the unique hardware imperfections resulting from the manufacturing process. Previous studies about radio frequency fingerprinting identification (RFFI) mainly concentrate on improving the accuracy which is evaluated by the single receiver device that trains and identifies all the nodes. Due to the mobility of the consumer electronic terminals, these terminal nodes may need to be identified by the different receivers. In this paper, we propose a cross-device radio frequency fingerprinting identification scheme which allows enrolled nodes to be authenticated by different devices. Motivated by the observation that signals collected by different receiver devices have a distribution shift that would violate the basic independent and identically distributed (i.i.d) assumption of supervised learning. Domain adaptation is adopted to improve the accuracy under different receivers, which can align the data captured from different devices and eliminate the distribution shift through the labeled data from one receiver device and unlabeled data from the other device. By this way, the distribution shift from different devices is corrected. Extensive experiment configurations under various Signal-to-noise ratio (SNR) are carried out to demonstrate the performance of domain adaptation with the same model structure. The results indicate that classification accuracy under different devices can be increased by 7%-15% and get a stable accuracy rate higher than 90% by leveraging our proposed cross-device RFFI scheme.
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| 4. |
- Frostegard, Johan, et al.
(författare)
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Atheroprotective natural anti-phosphorylcholine antibodies of IgM subclass are decreased in Swedish controls as compared to non-westernized individuals from New Guinea
- 2007
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Ingår i: Nutrition & Metabolism. - : Springer Science and Business Media LLC. - 1743-7075. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To determine the importance of IgM antibodies against phosphorylcholine ( aPC), a novel protective factor for cardiovascular disease ( CVD), in a population with a non-western life style as compared with a Swedish control group. Methods and results: Risk factors for cardiovascular disease were determined in a group of 108 individuals aged 40-86 years from New Guinea and 108 age-and sex-matched individuals from a population based study in Sweden. Antibodies were tested by ELISA. aPC IgM levels were significantly higher among New Guineans than among Swedish controls ( p < 0.0001). This difference remained significant among both men and women when controlled for LDL and blood pressure which were lower and smoking which was more prevalent in New Guineans as compared to Swedish controls ( p < 0.0001). aPC IgM was significantly and negatively associated with age and systolic blood pressure among Swedish controls and with waist circumference among New Guineans. aPC IgM levels were significantly higher among women than men in both groups. The proportion of the saturated fatty acid ( FA) myristic acid in serum cholesterol esters was negatively but polyunsaturated eicosapentaenoic acid and also lipoprotein ( a) were positively associated with aPC IgM levels. Conclusion: IgM-antibodies against PC, which have atheroprotective properties, are higher in a population from Kitava, New Guinea with a traditional lifestyle, than in Swedish Controls, and higher among women than men in both populations tested. Such antibodies could contribute to the low incidence of cardiovascular disease reported from Kitava and could also provide an explanation as to why women have a later onset of CVD than men.
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| 5. |
- Kauppila, Joonas H., et al.
(författare)
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Risk Factors for Suicide After Bariatric Surgery in a Population-based Nationwide Study in Five Nordic Countries
- 2022
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Ingår i: Annals of Surgery. - : Lippincott Williams & Wilkins. - 0003-4932 .- 1528-1140. ; 275:2, s. E410-E414
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Tidskriftsartikel (refereegranskat)abstract
- Objective:To identify risk factors for suicide after bariatric surgery.Summary background data:Bariatric surgery reduces obesity-related mortality. However, it is for unclear reasons is associated with an increased risk of suicide.Methods:This population-based cohort study included patients having undergone bariatric surgery in 1982 to 2012 in any of the 5 Nordic countries, with follow-up through 2012. Eleven potential risk factors of suicide (sex, age, comorbidity, surgery type, surgical approach, calendar year of surgery, history of depression or anxiety, psychosis, schizophrenia, mania, or bipolar disorder, personality disorder, substance use, and number of previously documented psychiatric diagnoses) were analyzed using Cox regression.Results:Of 49,977 bariatric surgery patients, 98 (0.2%) committed suicide during follow-up. Women had a decreased risk of suicide compared to men (hazard ratio [HR] = 0.48, 95% confidence interval [CI] 0.33-0.77), although age and comorbidity did not influence this risk. Compared to gastric bypass, other types of bariatric surgery had lower risk of suicide (HR = 0.44, 95%CI 0.27-0.99). There was no difference in suicide risk between laparoscopic and open surgical approach. A history of depression or anxiety (HR = 6.87, 95%CI 3.97-11.90); mania, bipolar disorder, psychosis, or schizophrenia (HR = 2.70, 95%CI 1.14-6.37); and substance use (HR = 2.28, 95%CI 1.08-4.80), increased the risk of suicide. More of the above psychiatric diagnoses increased the risk of suicide (HR = 22.59, 95%CI 12.96-39.38 for ≥2 compared to 0 diagnoses).Conclusions:Although the risk of suicide is low, psychiatric disorders, male sex, and gastric bypass procedure seem to increase the risk of suicide after bariatric surgery, indicating a role for tailored preoperative psychiatric evaluation and postoperative surveillance.
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| 6. |
- Maret-Ouda, John, et al.
(författare)
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Esophageal adenocarcinoma after obesity surgery in a population-based cohort study
- 2015
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Ingår i: Surgery for Obesity and Related Diseases. - Stockholm : Karolinska Institutet, Dept of Molecular Medicine and Surgery. - 1550-7289. ; 13:1, s. 28-34
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Tidskriftsartikel (refereegranskat)abstract
- Background: Obesity is strongly associated with esophageal adenocarcinoma (EAC), yet whether weight loss reduces the risk of EAC is unclear. Objectives: To test the hypothesis that the risk of EAC decreases following weight reduction achieved by obesity surgery. Setting: Nationwide register-based cohort study. Methods: This study included a majority of individuals who underwent obesity surgery in Sweden in 1980-2012. The incidence of EAC following obesity surgery was compared to the incidence in the corresponding background population of Sweden by means of calculation of standardized incidence ratios (SIRs) with 95% confidence intervals (CIs). The risk of EAC after obesity surgery was also compared with the risk in non-operated obese individuals by means of multivariable Cox regression, providing hazard ratios (HRs) with 95% CIs, adjusted for potential confounders. Results: Among 34,437 study participants undergoing obesity surgery and 239,775 person- 15" years of follow-up, 8 cases of EAC occurred (SIR 1.6, 95% CI 0.7-3.2). No clear trend of decreased SIRs was seen in relation to increased follow-up time after surgery. The SIR of EACs (n=53) among 123,695 non-operated obese individuals (673,238 person-years) was increased to a similar extent as in the obesity surgery cohort (SIR=1.9, 95% CI 1.4-2.5). Cox regression showed no difference in risk of EAC between operated and non-operated participants (adjusted HR=0.9, 95% CI 0.4-1.9). Conclusions: The risk of EAC might not decrease following obesity surgery, but even larger studies with longer follow-up are needed to establish this association.
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| 7. |
- Maret-Ouda, John, et al.
(författare)
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Nordic registry-based cohort studies : possibilities and pitfalls when combining Nordic registry data
- 2017
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Ingår i: Scandinavian Journal of Public Health. - Stockholm : Karolinska Institutet, Dept of Molecular Medicine and Surgery. - 1403-4948 .- 1651-1905.
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Tidskriftsartikel (refereegranskat)abstract
- Aims: All five Nordic countries (Denmark, Finland, Iceland, Norway, and Sweden) have nationwide registries with similar data structure and validity, as well as personal identity numbers enabling linkage between registries. These resources provide opportunities for medical research that is based on large registry-based cohort studies with long and complete follow-up. This review describes practical aspects, opportunities, and challenges encountered when setting up all-Nordic registry-based cohort studies. Methods: Relevant articles describing registries often used for medical research in the Nordic countries were retrieved. Further, our experiences of conducting this type of study, including planning, acquiring permissions, data retrieval, and data cleaning and handling, and the possibilities and challenges we have encountered, are described. Results: Combining data from the Nordic countries makes it possible to create large and powerful cohorts. The main challenges include obtaining all permissions within each country, usually in the local language, and to retrieve the data. These challenges emphasise the importance of having experienced collaborators within each country. Following the acquisition of data, data management requires the understanding of differences between the variables to be used in the various countries. A concern is the long time required between initiation and completion. Conclusions: Nationwide Nordic registries can be combined into cohorts with high validity and statistical power, but the considerable expertise, workload, and time required to complete such cohorts should not be underestimated.
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| 8. |
- Shi, Xun, et al.
(författare)
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Ultrafast electron calorimetry uncovers a new long-lived metastable state in 1T-TaSe2 mediated by mode-selective electron-phonon coupling
- 2019
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 5:3
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Tidskriftsartikel (refereegranskat)abstract
- Quantum materials represent one of the most promising frontiers in the quest for faster, lightweight, energy-efficient technologies. However, their inherent complexity and rich phase landscape make them challenging to understand or manipulate. Here, we present a new ultrafast electron calorimetry technique that can systematically uncover new phases of quantum matter. Using time- and angle-resolved photoemission spectroscopy, we measure the dynamic electron temperature, band structure, and heat capacity. This approach allows us to uncover a new long-lived metastable state in the charge density wave material 1T-TaSe2, which is distinct from all the known equilibrium phases: It is characterized by a substantially reduced effective total heat capacity that is only 30% of the normal value, because of selective electron-phonon coupling to a subset of phonon modes. As a result, less energy is required to melt the charge order and transform the state of the material than under thermal equilibrium conditions.
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| 9. |
- Tao, Wenjing
(författare)
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Cancer after bariatric surgery : risk and prognosis
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Obesity is a major public health challenge with a rapidly growing prevalence worldwide. The condition increases the risk of multiple diseases, including cancer in different locations. Current evidence on the effect of intentional weight loss on cancer is inconclusive. Bariatric surgery results in extensive and sustained weight loss with positive impact on several obesity-related comorbidities. It can therefore serve as a proxy for intentional weight. The few studies available suggest that bariatric surgery may decrease overall cancer risk but increase the risk of cancer in specific tumor locations. This thesis assesses the impact of bariatric surgery on cancer risk and cancer mortality using the Nordic Obesity Surgery Cohort (NordOSCo). The cohort includes individuals with an obesity diagnosis recorded in the National Patient Registries in any of the five Nordic countries between 1980 and 2012. Study I and IV included Swedish cohort members only, while Study II and III included the entire cohort. Study I validated bariatric surgery codes in the Swedish Patient Registry and the Scandinavian Obesity Surgery Registry (SOReg) against medical records for bariatric surgery performed during 2011. The accuracy of the codes proved to be high; 93.5% in the Patient Registry and 98.6% in SOReg. However, one fifth of the procedures in SOReg were not registered in the Patient Registry, indicating that the completeness of bariatric surgery registrations in the Patient Registry can be improved. Study II evaluated the association between bariatric surgery and the risk of obesityrelated cancer, non-obesity related cancer and cancer in selected sites. The study found an overall decreased risk of cancer following bariatric surgery that was more evident for cancers associated with obesity, particularly breast cancer, endometrial cancer and nonHodgkin lymphoma in women. The lower cancer risk was primarily observed during the initial years following surgery and this decrease diminished with time after surgery. In contrast, the risk of kidney cancer was increased among bariatric surgery patients. Study III and IV focused on colorectal cancer and studied the impact of bariatric surgery on the risk and prognosis of this disease. Incidence rates of colon cancer were higher in bariatric surgery patients than in the general population, especially after ≥10 years post-surgery. The elevated incidence rates exceeded that of obese individuals without bariatric surgery. No associations were observed for rectal cancer. On the contrary, cancer-specific mortality after rectal cancer diagnosis was more than three-fold increased among bariatric surgery patients compared to obese individuals without this surgery, but no differences in survival were observed between the exposure groups following colon cancer diagnosis. In conclusion, the Swedish Patient Registry is a valid data source for research on bariatric surgery. Overall cancer incidence seems to decrease after bariatric surgery, but the effect varies between cancer sites with a possible increase in the risk of colon and kidney cancer. Bariatric surgery may also decrease the chance of survival in rectal cancer.
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| 10. |
- Tao, Wenjing, et al.
(författare)
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Colorectal cancer prognosis following obesity surgery in a population-based cohort study
- 2016
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Ingår i: Obesity Surgery. - Stockholm : Karolinska Institutet, Dept of Molecular Medicine and Surgery. - 0960-8923 .- 1708-0428.
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Obesity surgery involves mechanical and physiological changes of the gastrointestinal tract that might promote colorectal cancer progression. Thus, we hypothesised that obesity surgery is associated with poorer prognosis in patients with colorectal cancer. METHODS: This nationwide population-based cohort study included all patients with an obesity diagnosis who subsequently developed colorectal cancer in Sweden from 1980 to 2012. The exposure was obesity surgery, and the main and secondary outcomes were disease-specific mortality and all-cause mortality, respectively. Cox proportional hazard survival models were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs), adjusted for sex, age, calendar year and education level. RESULTS: The exposed and unexposed cohort included 131 obesity surgery and 1332 non-obesity surgery patients with colorectal cancer. There was a statistically significant increased rate of colorectal cancer deaths following obesity surgery (disease-specific HR 1.50, 95% CI 1.00-2.19). When analysed separately, the mortality rate was more than threefold increased in rectal cancer patients with prior obesity surgery (disease-specific HR 3.70, 95% CI 2.00-6.90), while no increased mortality rate was found in colon cancer patients (disease-specific HR 1.10, 85% CI 0.67-1.70). CONCLUSION: This population-based study among obese individuals found a poorer prognosis in colorectal cancer following obesity surgery, which was primarily driven by the higher mortality rate in rectal cancer.
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