Emergence of fractal geometries in the evolution of a metabolic enzyme.

Fractals are patterns that are self-similar across multiple length-scales1. Macroscopic fractals are common in nature2-4; however, so far, molecular assembly into fractals is restricted to synthetic systems5-12. Here we report the discovery of a natural protein, citrate synthase from the cyanobacterium Synechococcus elongatus, which self-assembles into Sierpinski triangles. Using cryo-electron microscopy, we reveal how the fractal assembles from a hexameric building block. Although different stimuli modulate the formation of fractal complexes and these complexes can regulate the enzymatic activity of citrate synthase in vitro, the fractal may not serve a physiological function in vivo. We use ancestral sequence reconstruction to retrace how the citrate synthase fractal evolved from non-fractal precursors, and the results suggest it may have emerged as a harmless evolutionary accident. Our findings expand the space of possible protein complexes and demonstrate that intricate and regulatable assemblies can evolve in a single substitution.

High-Performance Molecular Dynamics Simulations for Native Mass Spectrometry of Large Protein Complexes with the Fast Multipole Method.

Native mass spectrometry (MS) is widely employed to study the structures and assemblies of proteins ranging from small monomers to megadalton complexes. Molecular dynamics (MD) simulation is a useful complement as it provides the spatial detail that native MS cannot offer. However, MD simulations performed in the gas phase have suffered from rapidly increasing computational costs with the system size. The primary bottleneck is the calculation of electrostatic forces, which are effective over long distances and must be explicitly computed for each atom pair, precluding efficient use of methods traditionally used to accelerate condensed-phase simulations. As a result, MD simulations have been unable to match the capacity of MS in probing large multimeric protein complexes. Here, we apply the fast multipole method (FMM) for computing the electrostatic forces, recently implemented by Kohnke et al. (J. Chem. Theory Comput., 2020, 16, 6938-6949), showing that it significantly enhances the performance of gas-phase simulations of large proteins. We assess how to achieve adequate accuracy and optimal performance with FMM, finding that it expands the accessible size range and time scales dramatically. Additionally, we simulate a 460 kDa ferritin complex over microsecond time scales, alongside complementary ion mobility (IM)-MS experiments, uncovering conformational changes that are not apparent from the IM-MS data alone.

Children's and adolescents' views of health and mental health concepts - A qualitative group interview study.

BACKGROUND: Definitions and perceptions of health and mental health have not remained static over time. This is also true for statistics over Swedish children's and adolescents' health and mental health status. The majority of Swedish school-aged children and adolescents report good physical health and good life satisfaction. However, there are some warning signs when it comes to children's and adolescents' health and mental health status, for instance, an increased overweight or obesity in children and adolescents, as well as a higher proportion reporting psychological problems and stress. There is also a need for knowing more about the younger population's voices in this matter. The aim was therefore to explore children's and adolescent's conceptualizations and perceptions of health in general, and mental health in particular. METHODS: Open semistructured group interviews with 44 Swedish children and adolescents (10-14 years old) recruited from four schools were conducted. The interviews were conducted between April 2022 and January 2023. Data were analyzed with qualitative content analysis. RESULTS: Children's and adolescents' conceptualizations of health included aspects of both the body and the mind, with a focus on the latter. Mental health was expressed as a state of being, illustrated by various lived experiences of emotions, moods, and thoughts. The social world was ever present in their understanding of health, e.g., through the lenses of social and gender norms. CONCLUSIONS: This study revealed children's and adolescents' recognition of health terms and their ability to observe nuances between mental health problems and everyday struggles. The participants discussed mental health problems to a greater extent than positive mental health. An implication of this study is the highlighted need to focus more on mental health promotion in future preventive programs. These findings might potentially influence how school staff and student health teams communicate with children and adolescents about these concepts.

Spinal surgery and the risk of reoperation after total hip arthroplasty: a cohort study based on Swedish spine and hip arthroplasty registers.

BACKGROUND AND PURPOSE: Studies suggest increased revision risk of total hip arthroplasty (THA) in individuals with lumbar spinal fusion, but studies including non-fused individuals are lacking. We aimed to investigate whether individuals undergoing lumbar spinal stenosis surgery with or without fusion are at an increased risk of reoperation before or after THA. PATIENTS AND METHODS: The Swedish Spine Register and the Swedish arthroplasty register were searched from 2000 through 2021. Chi-square, Kaplan-Meier and binary multivariate logistic regression were used to compare reoperation rates up to 10 years after THA surgery. RESULTS: 7,908 individuals had undergone lumbar spinal stenosis surgery (LSSS) (fusion n = 1,281) and THA. LSSS before THA compared with THA-only controls was associated with a higher risk of THA reoperations: 87 (2%) out of 3,892 vs. 123 (1%) out of 11,662 (P < 0.001). LSSS after THA compared with THA-only controls was not associated with a higher risk of reoperation, confirmed by Kaplan- Meier analyses and binary multivariate logistic regression. Mortality was lower in individuals undergoing both LSSS and THA, regardless of procedure order. There was no difference in THA reoperations in individuals who had undergone LSSS before THA without fusion or with fusion. The individuals who had undergone LSSS after THA with fusion had an increased risk of THA reoperation compared with those without fusion. CONCLUSION: LSSS with or without fusion before THA is associated with an increased risk of THA reoperation. Spinal fusion increased the risk of reoperation of THA when performed after THA.

School Nurses' Perspectives on Health among School-Aged Children and Adolescents During the COVID-19 Pandemic.

The aim of this study was to investigate school nurses' perspectives on students' health during the COVID-19 pandemic in Sweden in 2021. A cross-sectional survey design was used with school nurses (n = 225) working in schools in Sweden from elementary to upper secondary levels. The Clausson School Nurse Perception Questionnaire was used with two additional questions about the COVID-19 pandemic. The school nurses rated students' physical health as very good or good in 78% of the cases and their mental health as very good or good in 64%. There was also a negative trend in mental health during the pandemic, especially among girls. School nurses working in vulnerable areas (i.e., areas with a high proportion of immigrants and those receiving financial assistance) rated students' physical and mental health significantly worse compared other areas.

Improvements in the school environment-results of a Swedish school project 2005-2011.

To examine whether a public health project to reduce problem behavior in schools and improve the classroom climate, undertaken among eight secondary schools in a municipality in Sweden, was accompanied by favorable changes in the school environment over time. Data were collected from ninth grade students (aged 15-16 years) at three different time points: the year before the project began (2005), during the project (2008) and when the project finished (2011). Changes in the school environment, measured as damage, littering, noise and classroom disorder, were compared between the project municipality and a comparison group of other municipalities in the same county, using multinomial logistic regression analysis. Descriptive comparisons were made between the schools within the project municipality. The school environment improved significantly from 2005 to 2011 in the project municipality compared with the other municipalities. The school environment was improved in all schools within the project municipality. The biggest improvements took place in two schools which systematically worked with one program incorporated into the school schedule. This study demonstrates that it may be possible to improve the school environment by implementing health programs. Further studies based on experimental designs are required in order to confirm the potential and efficiency of school health programs.

Analysis of Trace Element Concentrations and Antioxidant Enzyme Activity in Muscle Tissue of the Atlantic Sharpnose Shark, Rhizoprionodon terraenovae.

Metals occur naturally in the environment; however, anthropogenic practices have greatly increased metal concentrations in waterways, sediments, and biota. Metals pose health risks to marine organisms and have been associated with oxidative stress, which can lead to protein denaturation, DNA mutations, and cellular apoptosis. Sharks are important species ecologically, recreationally, and commercially. Because they occupy a high trophic level, assessing muscle tissue metal concentrations in sharks may reflect metal transfer in marine food webs. In this study, concentrations of cadmium, copper, lead, nickel, selenium, silver, and zinc were measured in the muscle of Rhizoprionodon terraenovae (Atlantic sharpnose shark) from 12 sites along the coast of the southeastern United States. Activities of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase) also were examined in the muscle tissue of R. terraenovae. A total of 165 samples were analyzed, and differences in trace element bioaccumulation and enzyme activity were observed across sites. R. terraenovae samples collected from South Florida and South Carolina had the highest cumulative trace element concentrations whereas those collected from North Carolina and Alabama had the lowest cumulative concentrations. Trace element concentrations in shark muscle tissue were significantly correlated to antioxidant enzyme activity, particularly with glutathione peroxidase, suggesting that this enzyme may serve as a non-lethal, biomarker of metal exposure in R. terraenovae. This is one of the most extensive studies providing reference levels of trace elements and oxidative stress enzymes in a single elasmobranch species within the U.S.

Antimicrobial peptide levels are linked to airway inflammation, bacterial colonisation and exacerbations in chronic obstructive pulmonary disease.

Antimicrobial peptides (AMPs) are effectors of host defence against infection, inflammation and wound repair. We aimed to study AMP levels in stable chronic obstructive pulmonary disease (COPD) and during acute exacerbations of COPD (AECOPD), and to examine their relation to clinical parameters and inflammatory markers.The 3-year Bergen COPD Cohort Study included 433 COPD patients and 325 controls. Induced sputum was obtained and analysed for levels of the AMPs human cathelicidin (hCAP18/LL-37) and secretory leukocyte protease inhibitor (SLPI), and for the inflammatory markers interleukin (IL)-8, IL-6 and tumour necrosis factor-α (TNF-α) using immunoassays. Systemic hCAP18/LL-37 and vitamin D levels were also studied. Treating AMPs as response variables, non-parametric tests were applied for univariate comparison, and linear regression to obtain adjusted estimates. The risk of AECOPD was assessed by Cox proportional-hazard regression.Sputum AMP levels were higher in patients with stable COPD (n=215) compared to controls (n=45), and further changed during AECOPD (n=56), with increased hCAP18/LL-37 and decreased SLPI levels. Plasma hCAP18/LL-37 levels showed a similar pattern. In stable COPD, high sputum hCAP18/LL-37 levels were associated with increased risk of AECOPD, non-typeable Haemophilus influenzae colonisation, higher age, ex-smoking and higher levels of inflammatory markers.Altered levels of selected AMPs are linked to airway inflammation, infection and AECOPD, suggesting a role for these peptides in airway defence mechanisms in COPD.

Health promotion in Swedish schools: school managers' views.

Schools are recognized worldwide as settings for health promotion, and leadership has a bearing on schools' ability to be health promoting. School managers have a great influence on what is prioritized in school, which in turn affects students' school performance and health. There is lack of research into school managers' views on health promotion, and what they consider to be central to health promotion. The aim was therefore to examine school managers' views about what health promotion in schools include. An explorative design, qualitative content analysis, was performed. In-depth interviews were conducted with all 13 school managers of a middle-sized municipality in central Sweden. The analysis had both manifest and latent content and three categories: 'Organization and Collaboration', 'Optimize the arena' and 'Strengthen the individual', and 10 subcategories emerged. The theme, 'Opportunities for learning and a good life', describes the latent content of these categories. Taking into account the views of school managers are important because these views help form a more complete picture of how school managers work with health promotion and what is needed to enhance health promotion to improve students' opportunities for learning and a good life. The Ottawa Charter for Health promotion is thereby transformed into practice.

Comparison of inflammatory markers in induced and spontaneous sputum in a cohort of COPD patients.

BACKGROUND: Sputum induction is a non-invasive method for obtaining measurements of inflammation in the airways. Whether spontaneously sampled sputum can be a valid surrogate is unknown. The aim of this study was to compare levels of six inflammatory markers in sputum pairs consisting of induced and spontaneous sputum sampled on the same consultation either in a stable state or during exacerbations of chronic obstructive pulmonary disease (COPD). METHODS: 433 COPD patients aged 40-76, Global initiative for chronic Obstructive Lung Disease (GOLD) stage II-IV were enrolled in 2006/07 and followed every six months for three years. 356 patients were followed for potential exacerbations. Interleukin-6, interleukin-8, interleukin-18, interferon gamma-inducible protein-10, monokine induced by gamma interferon and tumor necrosis factor-alpha (IL-6, IL-8, IL-18, IP-10, MIG and TNF-α) were measured by bead based multiplex immunoassay in 60 paired sputum samples from 45 patients. Albumin was measured by enzyme immunoassay, for concentration correction. Culturing for bacterial growth was performed on 24 samples. Bland-Altman plots were used to assess agreement. The paired non-parametric Wilcoxon signed-rank test, the non-parametric Spearman's rank correlation test and Kruskal-Wallis test were used for statistical analyses. For all analyses, a p-value < 0.05 was considered significant. RESULTS: Agreement between the two measurements was generally low for all six markers. TNF-α was significantly higher in spontaneous sputum at exacerbations (p = 0.002) and trending higher at the steady state (p = 0.06). Correlation coefficients between the levels of markers in induced and spontaneous sputum varied between 0.58 (IL-18) to 0.83 (IP-10). In spontaneous sputum IL-18 and MIG were higher in ex-smokers (p < 0.05). The levels of all markers were higher in GOLD stage III & IV except for IL-6 in spontaneous sputum and IL-18 in induced sputum, compared with GOLD stage II, although not statistically significant. In spontaneous sputum the levels of IL-6 were significantly higher if Haemophilus influenzae (HI) was not cultured. CONCLUSION: We observed a low agreement and significant differences in inflammatory markers between induced and spontaneous sputum, both at steady state and exacerbations. We recommend considering sampling method when reporting on inflammatory markers in sputum.

School nurses' experiences of health-promoting work to prevent stress in Swedish adolescents.

Aim: To investigate school nurses' experiences of health-promoting work to prevent stress in Swedish adolescents. Materials and methods: Swedish school nurses (n = 225) responded to a web survey with open-ended questions. The results were subjected to a qualitative content analysis. Results: Six categories were identified from the analysis: (1) Knowledge of body and soul, (2) Identifying stress and ill health, (3) Collaborative working within/outside school, (4) Make yourself (i.e., school nurses) visible to the students, (5) Support students' learning, and (6) Tools for stress management. One of the most important themes in preventing and counteracting stress in school-aged children and adolescents was promoting healthy living habits. That school nurses were easily accessible and visible were important for them to identify stress as early as possible. The close collaboration with the school health care team and building relationships with the students were emphasized. The stress in adolescents was largely linked to schoolwork and performance anxiety. To counteract this, the dialogue with the teachers was important to increase their knowledge of mental health problems and stress and influence the scheduling of school exams. Conclusion: The study contributes to increased knowledge in the field and provides concrete strategies for how school nurses can work to counteract stress in students.

Sputum microbiota and inflammation at stable state and during exacerbations in a cohort of chronic obstructive pulmonary disease (COPD) patients.

BACKGROUND: Exacerbations of chronic obstructive pulmonary disease (COPD) are debilitating events and spur disease progression. Infectious causes are frequent; however, it is unknown to what extent exacerbations are caused by larger shifts in the airways' microbiota. The aim of the current study was to analyse the changes in microbial composition between stable state and during exacerbations, and the corresponding immune response. METHODS: The study sample included 36 COPD patients examined at stable state and exacerbation from the Bergen COPD Cohort and Exacerbations studies, and one patient who delivered sputum on 13 different occasions during the three-year study period. A physician examined the patients at all time points, and sputum induction was performed by stringent protocol. Only induced sputum samples were used in the current study, not spontaneously expectorated sputum. Sputum inflammatory markers (IL-6, IL-8, IL-18, IP-10, MIG, TNF-α) and antimicrobial peptides (AMPs, i.e. LL-37/hCAP-18, SLPI) were measured in supernatants, whereas target gene sequencing (16S rRNA) was performed on corresponding cell pellets. The microbiome bioinformatics platform QIIME2TM and the statistics environment R were applied for bioinformatics analyses. RESULTS: Levels of IP-10, MIG, TNF-α and AMPs were significantly different between the two disease states. Of 36 sample pairs, 24 had significant differences in the 12 most abundant genera between disease states. The diversity was significantly different in several individuals, but not when data was analysed on a group level. The one patient case study showed longitudinal dynamics in microbiota unrelated to disease state. CONCLUSION: Changes in the sputum microbiota with changing COPD disease states are common, and are accompanied by changes in inflammatory markers. However, the changes are highly individual and heterogeneous events.

Dynamic differences in dietary polyunsaturated fatty acid metabolism in sputum of COPD patients and controls.

INTRODUCTION: Disturbances in onset and resolution of inflammation in chronic obstructive pulmonary disease (COPD) are incompletely understood. Dietary polyunsaturated fatty acids (PUFAs) can be converted into lipid mediators here collectively named oxylipins. These include classical eicosanoids, but also pro-resolving mediators. A balanced production of pro-inflammatory and pro-resolving oxylipins is of importance for adequate inflammatory responses and subsequent return to homeostasis. OBJECTIVES: Here we investigated if PUFA metabolism is disturbed in COPD patients. METHODS: Free PUFA and oxylipin levels were measured in induced sputum samples from the Bergen COPD cohort and COPD exacerbation study using liquid chromatography-mass spectrometry. Additionally, effects of whole cigarette smoke on PUFA metabolism in air-liquid interface cultures of primary bronchial epithelial cells were assessed. RESULTS: Significantly lower levels of free alpha-linolenic acid, linoleic acid and eicosapentaenoic acid (EPA) were detected in sputum from stable COPD patients compared to controls. During acute exacerbation (AE), levels of free arachidonic acid and docosapentaenoic acid were higher than in stable COPD patients. Furthermore, levels of omega-3 EPA- and docosahexaenoic acid-derived oxylipins were lower in sputum from stable COPD patients compared to controls. Cyclooxygenase-2-converted mediators were mostly increased during AE. In vitro studies additionally showed that cigarette smoke exposure may also directly contribute to altered epithelial PUFA metabolism, and indirectly by causing airway epithelial remodelling. CONCLUSIONS: Our findings show significant differences in PUFA metabolism in COPD patients compared to controls, further changed during AE. Airway epithelial remodelling may contribute to these changes. These findings provide new insight in impaired inflammatory resolution in COPD.

Classmate characteristics, class composition and children's perceived classroom climate.

AIM: A beneficial classroom climate is vital for school achievements, health, well-being, and school satisfaction. However, there is little knowledge as to how the classmate characteristics and class composition are related to the level of a perceived messy and disorderly classroom climate and whether the estimated relationships vary between different groups of children. The aim of the study was to explore the relationship between classmate characteristics as well as class composition and children's perceived classroom climate. METHOD: Data from a cross-sectional survey administrated in 71 classes including 1,247 children in a mid-sized Swedish city were used. The analyses were conducted using multilevel models. RESULTS: A class with a higher proportion of girls was associated with a lower likelihood of perceiving the classroom climate as messy and disorderly. Moreover, a higher proportion of immigrant children in a class was associated with a perception of a messier and disorderly classroom climate among non-immigrant children, but not among immigrant children themselves. CONCLUSION: Classmate characteristics and class composition deserve more research attention and can be important considerations when aiming to improve the classroom climate and children's well-being in general.

School satisfaction and social relations: Swedish schoolchildren's improvement suggestions.

OBJECTIVES: The aim was to explore schoolchildren's views on how to increase school satisfaction and improve social relations among peers at school. METHOD: Improvement suggestions were collected from school children aged 10-12 years with the help of a feedback model developed for the purpose. Qualitative content analysis was used. RESULTS: Two categories emerged from the analysis: 'psychosocial climate', which included the subcategories 'adults' roles and responsibilities' and 'classmates' norms and values'; 'influence', which included the subcategories 'changes in the physical environment' and 'flexible learning'. The categories are seen as important to increase school satisfaction and improve social relations among peers at school. CONCLUSION: Examining children's opinions is requested and promoted by the UN convention on the Rights of the Child. The findings contribute to the field by showing how school satisfaction and social relations might be improved, if the child perspective is considered in the planning of health promotion activities in school.

Understanding and defining bullying - adolescents' own views.

BACKGROUND: The negative consequences of peer-victimization on children and adolescents are major public health concerns which have been subjected to extensive research. Given all efforts made to analyze and estimate the social and health consequences of peer-victimization, the adolescents' own experiences and understandings have had surprisingly little impact on the definition of bullying. Therefore, the aim of the current study is to explore adolescents' definitions of bullying. METHODS: A questionnaire study (n = 128) and four focus group interviews (n = 21) were conducted among students aged 13 and 15. First, gender and age differences were analyzed with respect to what behaviors are considered bullying (questionnaire data). Second, analysis of what bullying is (focus group interviews) was conducted using qualitative content analysis. RESULTS: The adolescents own understanding and definition of bullying didn't just include the traditional criteria of repetition and power imbalance, but also a criterion based on the health consequences of bullying. The results showed that a single but hurtful or harmful incident also could be considered bullying irrespective of whether the traditional criteria were fulfilled or not. Further, girls and older students had a more inclusive view of bullying and reported more types of behaviors as bullying compared to boys and younger students. CONCLUSIONS: The results of the current study adds to the existing literature by showing that adolescents consider the victim's experience of hurt and harm as a criterion for defining bullying and not only as consequences of bullying. This may be of special relevance for the identification and classification of bullying incidents on the internet where devastating consequences have been reported from single incidents and the use of the traditional criteria of intent, repetition and power imbalance may not be as relevant as for traditional bullying. It implies that the traditional criteria included in most definitions of bullying may not fully reflect adolescents' understanding and definition of bullying. Assessments of bullying behaviors that ask adolescents to strictly adhere to the traditional definition of bullying might not identify all adolescents experiencing peer victimization and therefore not provide estimates of prevalence rates reflecting adolescents' own understanding of bullying.

Vitamin D, vitamin D binding protein, and longitudinal outcomes in COPD.

BACKGROUND: Associations between Vitamin D3 [25(OH)D], vitamin D binding protein (VDBP) and chronic obstructive pulmonary disease (COPD) are previously reported. We aimed to further investigate these associations on longitudinal outcomes. METHODS: 426 COPD patients from western Norway, GOLD stage II-IV, aged 40-76, were followed every six-month from 2006 through 2009 with spirometry, bioelectrical impedance measurements and registration of exacerbation frequency. Serum 25(OH)D and VDBP levels were determined at study-entry by high-performance liquid chromatography coupled with mass spectrometry and enzyme immunoassays respectively. Yearly change in lung function and body composition was assessed by generalized estimating equations (GEE), yearly exacerbation rate by negative binomial regression models, and 5 years all-cause mortality by Cox proportional-hazard regression. RESULTS: 1/3 of the patients had vitamin D deficiency (<20ng/mL) and a greater decline in both FEV1 and FVC, compared to patients with normal levels; for FEV1 this difference only reached statistical significance in the 28 patients with the lowest levels (<10ng/mL, p = 0.01). Neither 25(OH)D nor VDBP levels predicted exacerbation rate, change in fat free mass index or risk of death. CONCLUSION: Severe vitamin D deficiency may affect decline in lung function parameters in COPD. Neither 25(OH)D nor VDBP levels did otherwise predict markers of disease progression.

Predictors of exacerbations in chronic obstructive pulmonary disease--results from the Bergen COPD cohort study.

BACKGROUND: COPD exacerbations accelerate disease progression. AIMS: To examine if COPD characteristics and systemic inflammatory markers predict the risk for acute COPD exacerbation (AECOPD) frequency and duration. METHODS: 403 COPD patients, GOLD stage II-IV, aged 44-76 years were included in the Bergen COPD Cohort Study in 2006/07, and followed for 3 years. Examined baseline predictors were sex, age, body composition, smoking, AECOPD the last year, GOLD stage, Charlson comorbidity score (CCS), hypoxemia (PaO2<8 kPa), cough, use of inhaled steroids, and the inflammatory markers leucocytes, C-reactive protein (CRP), neutrophil gelatinase associated lipocalin (NGAL), soluble tumor necrosis factor receptor 1 (sTNF-R1), and osteoprotegrin (OPG). Negative binomial models with random effects were fitted to estimate the annual incidence rate ratios (IRR). For analysis of AECOPD duration, a generalized estimation equation logistic regression model was fitted, also adjusting for season, time since inclusion and AECOPD severity. RESULTS: After multivariate adjustment, significant predictors of AECOPD were: female sex [IRR 1.45 (1.14-1.84)], age per 10 year increase [1.23 (1.03-1.47)], >1 AECOPD last year before baseline [1.65 (1.24-2.21)], GOLD III [1.36 (1.07-1.74)], GOLD IV [2.90 (1.98-4.25)], chronic cough [1.64 (1.30-2.06)] and use of inhaled steroids [1.57 (1.21-2.05)]. For AECOPD duration more than three weeks, significant predictors after adjustment were: hypoxemia [0.60 (0.39-0.92)], years since inclusion [1.19 (1.03-1.37)], AECOPD severity; moderate [OR 1.58 (1.14-2.18)] and severe [2.34 (1.58-3.49)], season; winter [1.51 (1.08-2.12)], spring [1.45 (1.02-2.05)] and sTNF-R1 per SD increase [1.16 (1.00-1.35)]. CONCLUSION: Several COPD characteristics were independent predictors of both AECOPD frequency and duration.

Chronic obstructive pulmonary disease is associated with low levels of vitamin D.

INTRODUCTION: COPD patients may be at increased risk for vitamin D (25(OH)D) deficiency, but risk factors for deficiency among COPD patients have not been extensively reported. METHODS: Serum 25(OH)D levels were measured by liquid chromatography double mass spectrometry in subjects aged 40-76 years from Western Norway, including 433 COPD patients (GOLD stage II-IV) and 325 controls. Levels <20 ng/mL defined deficiency. Season, sex, age, body mass index (BMI), smoking, GOLD stage, exacerbation frequency, arterial oxygen tension (PaO(2)), respiratory symptoms, depression (CES-D score≥16), comorbidities (Charlson score), treatment for osteoporosis, use of inhaled steroids, and total white blood count were examined for associations with 25(OH)D in both linear and logistic regression models. RESULTS: COPD patients had an increased risk for vitamin D deficiency compared to controls after adjustment for seasonality, age, smoking and BMI. Variables associated with lower 25(OH)D levels in COPD patients were obesity ( = -6.63), current smoking ( = -4.02), GOLD stage III- IV ( = -4.71, = -5.64), and depression ( = -3.29). Summertime decreased the risk of vitamin D deficiency (OR = 0.22). CONCLUSION: COPD was associated with an increased risk of vitamin D deficiency, and important disease characteristics were significantly related to 25(OH)D levels.