Insomnia symptoms and risk for atrial fibrillation - The HUNT study

Studies on the effect of insomnia on atrial fibrillation risk in the general population are limited, therefore we investigated the association between insomnia and the risk of atrial fibrillation in a large-scale population-based study with valid atrial fibrillation measure. A total of 33,983 participants (55% women) reported their insomnia symptoms in the third wave of the HUNT study (between 2006 and 2008) in Norway, and they were followed for their first atrial fibrillation diagnosis until 2020 using hospital registers. Atrial fibrillation diagnoses were validated by physicians based on medical records and electrocardiograms. Insomnia symptoms were assessed by four questions, and analysed both individually and as cumulative symptoms. Cox regression, adjusted for age, sex, social and marital status, working in shiftwork, alcohol consumption, smoking, physical activity, body mass index, systolic blood pressure, and symptoms of anxiety and depression, was conducted. Overall, 1592 atrial fibrillation cases were identified during the follow-up and 31.6% of individuals reported at least one insomnia symptom. In our analysis, we did not detect meaningful associations between insomnia symptoms and the risk of atrial fibrillation. In conclusion, in this population there was no evidence for an association between insomnia symptoms and the risk of subsequent atrial fibrillation.

Hypothetical 22-Year Intervention With the Dietary Approaches to Stop Hypertension and Risk of Heart Failure in a General Population

We used design principles of target trial methodology to emulate the effect of sustained adherence to the Dietary Approaches to Stop Hypertension (DASH) diet on the 22-year risk of heart failure. Women and men aged 45-83 years without previous heart failure, who answered questionnaires in 1997 from the Swedish Mammography Cohort and the Cohort of Swedish Men, were eligible. Follow-up questionnaires were sent in 2008-2009. Incidence of heart failure was ascertained using the Swedish Patient Register, updated until December 31, 2019. The parametric g-formula was used to estimate the 22-year risk of heart failure under sustained adherence to a population-adapted DASH diet compared with no intervention. Intakes before 1997 for before-baseline adjustment was available only for women. In total, 31,238 women and 34,939 men were eligible. The 22-year risk of heart failure was 14.5% with long-term adherence to the DASH diet compared with 15.2% with no intervention (risk difference = -0.7%, 95% confidence interval: 1.6, 0.0%) in women and correspondingly in men 15.3% vs. 16.2% (risk difference = -0.9%, 95% confidence interval: -1.6, -0.2%). Our hypothetical intervention suggests that sustained adherence to the population-adapted DASH diet may reduce risk of heart failure in middle-aged and elderly Swedish women and men.

Understanding the protective effect of social support on depression symptomatology from a longitudinal network perspective

BACKGROUND

Higher social support protects people from developing mental disorders. Limited evidence is available on the mechanism through which social support plays this protective role.

OBJECTIVE

To investigate the stress-buffering process of social support on depressive symptoms using a novel longitudinal dynamic symptom network approach.

METHODS

A total of 4242 adult participants who completed the first two waves (from May to October 2020) of the International Covid Mental Health Survey were included in the study. Cross-lagged panel network modelling was used to estimate a longitudinal network of self-reported social support, loneliness and depressive symptoms. Standardised regression coefficients from regularised cross-lagged regressions were estimated as edge weights of the network.

FINDINGS

The results support a unidirectional protective effect of social support on key depressive symptoms, partly mediated through loneliness: A higher number of close confidants and accessible practical help was associated with decreased anhedonia (weight=-0.033) and negative self-appraisal symptoms (weight=-0.038). Support from others was also negatively associated with loneliness, which in turn associated with decreased depressed mood (weight=0.086) and negative self-appraisal (weight=0.077). We identified a greater number of direct relationships from social support to depressive symptoms among men compared with women. Also, the edge weights from social support to depression were generally stronger in the men's network.

CONCLUSIONS

Reductions in negative self-appraisal might function as a bridge between social support and other depressive symptoms, and, thus, it may have amplified the protective effect of social support. Men appear to benefit more from social support than women.

CLINICAL IMPLICATIONS

Building community-based support networks to deliver practical support, and loneliness reduction components are critical for depression prevention interventions after stressful experiences.

Nitro-oxidative response to internalized multi-walled carbon nanotubes in Brassica napus and Solanum lycopersicum

In addition to their beneficial effects on plant physiology, multi-walled carbon nanotubes (MWCNTs) are harmful to plants in elevated concentrations. This study compared the effects of two doses of MWCNT (10 and 80 mg/L) in Brassica napus and Solanum lycopersicum seedlings focusing on nitro-oxidative processes. The presence of MWCNTs was detectable in the root and hypocotyl of both species. Additionally, transmission electron microscopy analysis revealed that MWCNTs are heavily transformed within the root cells forming large aggregates. The uptake of MWCNTs negatively affected root viability and root cell proliferation of both species, but more intense toxicity was observed in S. lycopersicum compared to B. napus. The presence of MWCNT triggered more intense protein carbonylation in the relative sensitive S. lycopersicum, where increased hydrogen peroxide levels were observed. Moreover, MWCNT exposure increased the level of physiological protein tyrosine nitration which was more intense in S. lycopersicum where notable peroxynitrite accumulation occurred. These suggest for the first time that MWCNT triggers secondary nitro-oxidative stress which contributes to its toxicity. Moreover, the results indicate that the extent of the nitro-oxidative processes is associated with the extent of MWCNT toxicity.

Subfunctionalization of Parental Polyamine Oxidase (PAO) Genes in the Allopolyploid Tobacco Nicotiana tabacum (L.)

Polyamines play an important role in developmental and environmental stress responses in plants. Polyamine oxidases (PAOs) are flavin-adenine-dinucleotide-dependent enzymes associated with polyamine catabolism. In this study, 14 genes were identified in the tobacco genome that code for PAO proteins being named based on their sequence homology with Arabidopsis PAOs (AtPAO1-5): NtPAO1A-B; NtPAO2A-C, NtPAO4A-D, and NtPAO5A-E. Sequence analysis confirmed that the PAO gene family of the allopolyploid hybrid Nicotiana tabacum is not an exact combination of the PAO genes of the maternal Nicotiana sylvestris and paternal Nicotiana tomentosiformis ones. The loss of the N. sylvestris homeolog of NtPAO5E and the gain of an extra NtPAO2 copy, likely of Nicotiana othophora origin, was revealed. The latter adds to the few pieces of evidence suggesting that the paternal parent of N. tabacum was an introgressed hybrid of N. tomentosiformis and N. othophora. Gene expression analysis indicated that all 14 PAO genes kept their expression following the formation of the hybrid species. The homeologous gene pairs showed similar or opposite regulation depending on the investigated organ, applied stress, or hormone treatment. The data indicate that the expression pattern of the homeologous genes is diversifying in a process of subfunctionalization.

Predictors of beverage-specific, alcohol consumption trajectories: A Swedish population-based cohort study

Aim: The aim of the study was to examine whether changes in alcohol consumption over time differ according to beverage types, and to what extent socioeconomic, lifestyle and health-related factors predict beverage-specific trajectories in Sweden. Study design: We included participants from the Stockholm Public Health Cohort who were surveyed repeatedly in 2002, 2010 and 2014. Alcohol consumption trajectories were constructed for 13,152 individuals with valid information on amount and frequency of drinking. Preferred beverage types (i.e., beer, wine or spirits) were defined based on the most consumed beverages. Multinomial logistic regression was used to quantify individual predictors of different trajectories, overall and by beverage type. Results: Overall 56.9% of respondents were women, the mean age was 49.2 years, SD (13.1). Wine was cited as the preferred beverage for 72.4% of participants, and stable moderate drinking was the most common trajectory regardless of beverage type (68.2%, 54.9% and 54.2% in individuals with wine, beer and spirits as preferred beverages, respectively). Associations between drinking trajectories and baseline lifestyle factors did not differ by beverage type. Lower socioeconomic position (SEP) was associated with unstable moderate wine drinking (for unskilled manual SEP: adjusted odds ratio [aOR] 1.54, 95% confidence interval [CI] 1.23, 1.93), unstable heavy beer drinking (for skilled manual SEP: aOR 1.99, 95% CI 1.14, 3.52; and unskilled manual SEP: aOR 1.72, 95% CI 1.05, 2.82), and former beer drinking trajectory (for skilled manual SEP: aOR 1.81; 95% CI 1.21, 2.72; and unskilled manual SEP: aOR 1.66; 95% CI 1.17, 2.37). Conclusion: Lower SEP was associated with unstable heavy drinking of beer, former beer drinking, and unstable moderate wine drinking trajectories indicating that targeted alcohol prevention programmes need to focus on these groups.

Risk of myocardial infarction after invasive outpatient procedures

OBJECTIVE

To assess the short-term risk of acute myocardial infarction (AMI) associated with procedures performed at outpatient specialised hospital clinics.

METHODS

In this case-crossover, population-based study, we identified first-time AMI cases aged ≥40 years via patient registries and linked them to their surgical intervention in Norway (2008-2016) and Sweden (2001-2014), respectively. The number of individuals with AMI who underwent procedures 0-7 days (hazard period) prior to the AMI diagnosis was compared with cases who were exposed 29-36 days (control period) before the AMI. A total of 6176 patients with AMI who underwent a procedure either during the defined hazard or control period contributed to the analyses. ORs with 95% CIs were computed using conditional logistic regression.

RESULTS

The mean age of the total population was 74.7 years and 64.6% were male. The relative risk was higher following procedures performed under general/regional anaesthesia for gastrointestinal endoscopy (OR_summary, 4.23, 95% CI 1.58 to 11.31), vascular (OR_summary, 3.12, 95% CI 1.10 to 8.90), urological/gynaecological (OR_summary, 2.30, 95% CI 1.50 to 3.53) and orthopaedic (OR_summary,1.78, 95% CI 1.30 to 2.44) procedures, and for ENT (ear, nose and throat) and mouth procedures (OR_summary, 1.53, 95% CI 1.19 to 1.99) performed under local anaesthesia.

CONCLUSION

This large population-based register study from two countries suggests that outpatient procedures are generally safe with regard to the postoperative risk of AMI. However, some procedures, such as gastrointestinal endoscopy, vascular procedures and urological/gynaecological procedures may increase the risk of AMI by twofold or threefold within the first 8 days after the procedures. Further studies are warranted to assess whether the effect is modified by cardiovascular medication or other clinical factors.

Working life sequences over the life course among 9269 women and men in Sweden; a prospective cohort study

OBJECTIVES

To investigate working life courses in women and men and possible associations with socioeconomic, health-, and work-related factors.

METHODS

A 15-year prospective cohort study of individuals aged 18-50 in paid work at baseline and answering the Swedish Living Conditions Surveys (2000-2003, N = 9269) and their annual economic activity, using nationwide registers. We used sequence and cluster analyses to identify and group similar working life sequences. Multinomial logistic regression was used to examine associations of sex, socioeconomic, health-, and work-related factors with sequence cluster memberships.

RESULTS

We identified 1284 working life sequences, of which 65% represented continuous active (in paid work/studying) states. We then identified five sequence clusters, the largest one with individuals who were continuously active (n = 6034, 65% of the participants; 54% of women and 76% of men) and smaller ones with interruptions of the active state by long-term parental-leave, unemployment, and/or sickness absence/disability pension (SA/DP), or retirement. Women were more likely than men to belong to the "Parental-leave periods" (odds ratio [OR]: 33.2; 95% confidence intervals [CI]: 25.6, 43.1) and the "SA/DP periods" sequence clusters (OR: 1.8; 95% CI: 1.4, 2.1), also after adjustment for covariates. In both sexes, low education and poor health were the strongest predictors of belonging to the sequence cluster "Unemployment & SA/DP periods". Predictors of the "Parental-leave periods" sequence cluster differed between women and men.

CONCLUSIONS

In a cohort of individuals in paid work at baseline, the majority of women and men worked most of each year although women were more likely to have some interruptions characterized by long-term parental-leave or SA/DP periods than men, independently of socioeconomic, health-, and work-related factors.

Period effects in the risk of labour market marginalization among refugees in Sweden: a register-based cohort study

BACKGROUND

Changes in Swedish national insurance policies over time and/or migration-related health inequalities may influence the risk for labour market marginalization (LMM) in refugees as compared to the Swedish-born host population. This study aimed to investigate potential period effects in the association between refugee status and the risk of LMM and explore any differences by country of birth, age and duration of residence.

METHODS

Using national registers, three cohorts including all Swedish residents during 1999, 2004 and 2009 were followed for 4 years (cohort 2000, 2005 and 2010). Cox regression models were used to examine associations between refugee status and LMM defined as long-term unemployment (>180 days annually) and disability pension. The analyses were adjusted for socio-demographic factors, morbidities and labour market-related factors. Stratified analyses were run for age, country of birth and duration of residence.

RESULTS

Across the cohorts, hazard ratios (HRs) were higher for long-term unemployment [2000: HR = 1.98; 95% confidence interval (CI): 1.96-2.01; 2005: HR = 2.30; 95% CI: 2.27-2.33; 2010: HR = 2.78; 95% CI: 2.75-2.81] for refugees compared to Swedish-born but not for disability pension. HRs for long-term unemployment were highest among refugees aged 25-34 and 35-44 years, from Somalia, Afghanistan and Iraq and refugees with a shorter duration of residence.

CONCLUSIONS

The risk of long-term unemployment appears to have increased for refugees over time. Particularly some refugee subgroups experienced more difficulties. These findings highlight ongoing disparities for refugees and implicate on a broader scale that changes in policies such as stricter regulations in the insurance or healthcare system might adversely affect them.

A prognostic model for predicting the duration of 20,049 sickness absence spells due to shoulder lesions in a population-based cohort in Sweden

MAIN OBJECTIVE

Sickness absence duration for shoulder lesion patients is difficult to prognosticate, and scientific evidence for the sick-listing practice is lacking. Our objective was to develop a clinically implementable prediction model for the duration of a sickness absence spell due to shoulder lesions.

METHODS

All new sickness absence spells due to shoulder lesions (ICD-10-code: M75) issued in the period January 2010-June 2012 that were longer than 14 days were identified through the nationwide sickness absence insurance register. Information on predictors was linked from four other nationwide registers. Piecewise-constant hazards regression models were fitted to predict duration of sickness absence. The model was developed and validated using split sample validation. Variable selection was based on log-likelihood loss ranking when excluding a variable from the model. The model was evaluated using calibration plots and the c-statistic.

RESULTS

20 049 sickness absence spells were identified, of which 34% lasted >90 days. Predictors included in the model were age, sex, geographical region, occupational status, educational level, birth country, specialized healthcare at start of the spell, number of sickness absence days in the last 12 months, and specialized healthcare the last 12 months, before start date of the index sickness absence spell. The model was satisfactorily specified and calibrated. Overall c-statistic was 0.54 (95% CI 0.53-0.55). C-statistic for predicting durations >90, >180, and >365 days was 0.61, 0.66, and 0.74, respectively.

SIGNIFICANCE

The model can be used to predict the duration of sickness absence due to shoulder lesions. Covariates had limited predictive power but could discriminate the very long sickness absence spells from the rest.

Absence of Arabidopsis Polyamine Oxidase 5 Influences the Cytokinin-Induced Shoot Meristem Formation from Lateral Root Primordia

Lateral root primordia (LRPs) of Arabidopsis can be directly converted to shoot meristems (SMs) by the application of exogenous cytokinin. Here, we report that Arabidopsis POLYAMINE OXIDASE 5 (AtPAO5) contributes to this process, since the rate of SM formation from LRPs was significantly lower in the pao5-2 knockout mutant. Furthermore, the presented experiments showed that AtPAO5 influences SM formation via controlling the thermospermine (T-Spm) level. Gene expression analyses supported the view that the pao5-2 mutation as well as exogenous T-Spm downregulate the expression of the class 3 haemoglobin coding genes AtGLB1 and AtGLB2. AtGLB1 and 2 have been reported to augment cytokinin sensitivity, indirectly inhibiting the expression of type-A ARABIDOPSIS RESPONSE REGULATORs (ARRs). In agreement, the same ARR-coding genes were found to be upregulated in the pao5-2 mutant. Although GLB proteins might also control cytokinin-induced nitric oxide (NO) accumulation, we could not find experimental evidence for it. Rather, the negative effect of NO-donor treatment on AtPAO5 gene expression and SM formation was seen. Nevertheless, a hypothetical pathway is set up explaining how AtPAO5 may affect direct shoot meristem formation, controlling cytokinin sensitivity through T-Spm and GLBs.

The role of sociodemographic and clinical factors in the initiation and discontinuation of attention deficit hyperactivity disorder medication among young adults in Sweden

Introduction

Long-term medication use is a recommended treatment for attention-deficit/hyperactivity disorder (ADHD), however, discontinuation is common. Non-medical factors which might influence initiation and discontinuation are understudied. Therefore, we investigated how different sociodemographic factors and comorbidities were associated with the initiation and discontinuation of ADHD medication use among young adults.

Methods and results

We conducted a population-based prospective cohort study using individually linked administrative register data, in which we included all individuals residing in Sweden, between the age of 19 and 29 who were first diagnosed with ADHD between January 2006 and December 2016 (n = 59224). ADHD medication initiation was defined as the first prescription of ADHD medication in the period from 3 months before to 6 months after the cohort entry date. Those who initiated ADHD medication were followed up for medication use until discontinuation, death/emigration, or until 2019. Logistic and Cox regression models were used to investigate the associations between sociodemographics, health-related predictors and initiation, as well as discontinuation. Overall, 48.7% of the 41399 individuals initiated ADHD medication, most often methylphenidate (87%). Among the initiators, 15462 (77%) discontinued medication use during the follow-up (median time: 150 days). After mutually adjusting all other predictors, initiation was positively associated with older age, male sex, higher level of education, and negatively associated with living at home with parents, immigrant status, being unemployed during the year before inclusion, being on disability pension, having autism, substance use, schizophrenia-spectrum disorders, other mental disability/developmental disorders, cardiovascular diseases or previous accidents. Discontinuation was positively associated with being born abroad, living in big cities, being unemployed during the year before inclusion, having cancer, and negatively associated with a higher educational level, having depression, anxiety or stress-related disorder, autism spectrum disorder or diabetes.

Conclusion

Besides medical factors, sociodemographics, such as educational attainment and immigrant status might also play a role in the initiation and discontinuation of ADHD medication use among young adults newly diagnosed with ADHD.

Symptoms of anxiety and depression during the COVID-19 pandemic in six European countries and Australia - Differences by prior mental disorders and migration status

BACKGROUND

Little is known about changes of mental health during the COVID-19 pandemic in potentially disadvantaged groups. We investigated changes in anxiety and depression symptoms during the first year of the pandemic in six European countries and Australia by prior mental disorders and migration status.

METHODS

Overall, 4674 adults answered a web-based survey in May-June 2020 and were followed by three repeated surveys up to February 2021. Information on psychosocial, financial and demographic, living conditions, prior mental disorders, depression and anxiety symptoms during the pandemic and migration status was collected. Weighted general estimation equations modelling was used to investigate the association between prior mental disorders, migration status, and symptoms over time.

RESULTS

Most participants were <40 years old (48%), women (78%) and highly educated (62%). The baseline prevalence of depressive and anxiety symptoms ranged between 19%-45% and 13%-35%, respectively. In most countries, prevalence rates remained unchanged throughout the pandemic and were higher among people with prior mental disorders than without even after adjustment for several factors. We observed interactions between previous mental disorders and symptoms of anxiety or depression over time in two countries. No difference by migration status was noted.

LIMITATIONS

Convenience sampling limits generalizability. Self-assessed symptoms of depression and anxiety might involve some misclassification.

CONCLUSIONS

Depression and anxiety symptoms were worse among individuals with prior mental disorders than without, but there was no clear trend of worsening mental health in the observed groups during the observed period.

Occupational Branch and Labor Market Marginalization among Young Employees with Adult Onset of Attention Deficit Hyperactivity Disorder-A Population-Based Matched Cohort Study

We compared labor market marginalization (LMM), conceptualized as days of unemployment, sickness absence and disability pension, across occupational branches (manufacturing, construction, trade, finance, health and social care, and education), among young employees with or without attention deficit hyperactivity disorder (ADHD) and examined whether sociodemographic and health-related factors explain these associations. All Swedish residents aged 19–29 years and employed between 1 January 2005 and 31 December 2011 were eligible. Individuals with a first ADHD diagnosis (n = 6030) were matched with ten controls and followed for five years. Zero-inflated negative binomial regression was used to model days of LMM with adjustments for sociodemographic and health-related factors. In total, 20% of those with ADHD and 59% of those without had no days of LMM during the follow-up. The median of those with LMM days with and without ADHD was 312 and 98 days. Having an ADHD diagnosis was associated with a higher incidence of LMM days (incident rate ratios (IRRs) 2.7–3.1) with no differences across occupational branches. Adjustments for sociodemographic and health-related factors explained most of the differences (IRRs: 1.4–1.7). In conclusion, young, employed adults with ADHD had a higher incidence of LMM days than those without, but there were no substantial differences between branches, even after adjusting for sociodemographic and health-related factors.

Mental and somatic disorders and the subsequent risk of all-cause and cause-specific mortality in refugees, non-refugee migrants and the Swedish-born youth: a population-based cohort study in Sweden

OBJECTIVES

The aims were to investigate the associations between specific mental and somatic disorders and subsequent all-cause and cause-specific mortality (suicide, external and other causes) in young refugees and non-refugee migrants compared with Swedish-born individuals of similar age.

METHODS

In this register-based prospective cohort study, all 1 003 760 individuals (40 305 refugees, 31 687 non-refugee migrants as the exposure groups and the rest as the Swedish-born comparison group), 16-25 years old, residing in Sweden on 31 December 2004 were included. These individuals were followed regarding the outcome of all-cause and cause-specific mortality (suicide and external causes) between 2005 and 2016. The study population was also stratified according to any use of specialised healthcare for mental or somatic diagnoses before baseline (2000-2004). Cox regression models yielding crude and multivariate Hazard Ratios (HR and aHR, respectively) with 95% Confidence Intervals (CI) were used to investigate the afore-mentioned associations.

RESULTS

A lower proportion of both refugees (12%) and non-refugee migrants (10%) had college/university education compared with the Swedish-born individuals (17%). The proportion of unemployed (>180 days) among refugees (2.3%) and non-refugees (2.9%) was higher than the Swedish born (1.4%). Refugees and non-refugee migrants had about a 20% lower risk of all-cause mortality and external causes of mortality compared with Swedish-born individuals. An even greater reduction in suicide risk (aHR 0.51, 95% CI 0.37 to 0.70, and 0.63, 95% CI 0.49 to 0.82 for non-refugees and refugees, respectively) was found. When restricted to those with a mental or somatic disorder, a lower risk of both general and specific mortality was also found among both refugees and non-refugee migrants compared with Swedish-born individuals. Refugees had, however, equal point estimates of all-cause mortality associated with substance misuse disorder and neoplasms as their Swedish-born peers with these disorders.

CONCLUSIONS

With few exceptions, young migrants with specific mental and somatic disorders have a mortality advantage compared with their Swedish-born peers with the same disorders. Further research on protective factors is warranted.

Risk for Acute Myocardial Infarction After Ophthalmologic Procedures

BACKGROUND

Preoperative cardiovascular evaluations are frequently done before ambulatory ophthalmologic procedures. However, whether these procedures can trigger an acute myocardial infarction (AMI) is unknown.

OBJECTIVE

To assess the short-term risk for AMI associated with ophthalmologic procedures.

DESIGN

Case-crossover design.

SETTING

Population-based nationwide study from Norway and Sweden.

PARTICIPANTS

First-time patients with AMI, aged 40 years and older, identified via inpatient registries and linked to outpatient surgical procedures in Norway (2008 to 2014) and Sweden (2001 to 2014), respectively.

MEASUREMENTS

Using self-matching, for each participant, exposure to ophthalmologic procedures in the 0 to 7 days before AMI diagnosis (hazard period) was compared with an 8-day period 30 days earlier, that is, days 29 to 36 before AMI (control period) to estimate the relative risk for an AMI the week after an ophthalmologic procedure. The odds ratios (ORs) with 95% CIs were calculated, using conditional logistic regression. Only patients who had a procedure of interest during either the hazard or control period were included.

RESULTS

For the 806 patients with AMI included in this study, there was a lower likelihood of AMI in the week after an ophthalmologic procedure than during the control week (OR_, 0.83; 95% CI, 0.75 to 0.91). Furthermore, there was no evidence of increased risk for AMI when analyses were stratified by surgery subtype, anesthesia (local or general), duration, invasiveness (low, intermediate, or high), patient's age (<65 years or ≥65 years), or comorbidity (none vs. any).

LIMITATION

Potential bias from time-varying confounders between the hazard and the control periods.

CONCLUSION

Ophthalmologic procedures done in an outpatient setting did not seem to be associated with an increased risk for AMI.

PRIMARY FUNDING SOURCE

Central Norway Regional Health Authority and the Swedish Research Council.

Predicting the duration of sickness absence due to knee osteoarthritis: a prognostic model developed in a population-based cohort in Sweden

Background

Predicting the duration of sickness absence (SA) among sickness absent patients is a task many sickness certifying physicians as well as social insurance officers struggle with. Our aim was to develop a prediction model for prognosticating the duration of SA due to knee osteoarthritis.

Methods

A population-based prospective study of SA spells was conducted using comprehensive microdata linked from five Swedish nationwide registers. All 12,098 new SA spells > 14 days due to knee osteoarthritis in 1/1 2010 through 30/6 2012 were included for individuals 18–64 years. The data was split into a development dataset (70 %, n_spells =8468) and a validation data set (n_spells =3690) for internal validation. Piecewise-constant hazards regression was performed to prognosticate the duration of SA (overall duration and duration > 90, >180, or > 365 days). Possible predictors were selected based on the log-likelihood loss when excluding them from the model.

Results

Of all SA spells, 53 % were > 90 days and 3 % >365 days. Factors included in the final model were age, sex, geographical region, extent of sickness absence, previous sickness absence, history of specialized outpatient healthcare and/or inpatient healthcare, employment status, and educational level. The model was well calibrated. Overall, discrimination was poor (c = 0.53, 95 % confidence interval (CI) 0.52–0.54). For predicting SA > 90 days, discrimination as measured by AUC was 0.63 (95 % CI 0.61–0.65), for > 180 days, 0.69 (95 % CI 0.65–0.71), and for SA > 365 days, AUC was 0.75 (95 % CI 0.72–0.78).

Conclusion

It was possible to predict patients at risk of long-term SA (> 180 days) with acceptable precision. However, the prediction of duration of SA spells due to knee osteoarthritis has room for improvement.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04400-8.

Polyamine Metabolism Is Involved in the Direct Regeneration of Shoots from Arabidopsis Lateral Root Primordia

Plants can be regenerated from various explants/tissues via de novo shoot meristem formation. Most of these regeneration pathways are indirect and involve callus formation. Besides plant hormones, the role of polyamines (PAs) has been implicated in these processes. Interestingly, the lateral root primordia (LRPs) of Arabidopsis can be directly converted to shoot meristems by exogenous cytokinin application. In this system, no callus formation takes place. We report that the level of PAs, especially that of spermidine (Spd), increased during meristem conversion and the application of exogenous Spd improved its efficiency. The high endogenous Spd level could be due to enhanced synthesis as indicated by the augmented relative expression of PA synthesis genes (AtADC1,2, AtSAMDC2,4, AtSPDS1,2) during the process. However, the effect of PAs on shoot meristem formation might also be dependent on their catabolism. The expression of Arabidopsis POLYAMINE OXIDASE 5 (AtPAO5) was shown to be specifically high during the process and its ectopic overexpression increased the LRP-to-shoot conversion efficiency. This was correlated with Spd accumulation in the roots and ROS accumulation in the converting LRPs. The potential ways how PAO5 may influence direct shoot organogenesis from Arabidopsis LRPs are discussed.

Burden and prevalence of prognostic factors for severe COVID-19 in Sweden

The World Health Organization and European Centre for Disease Prevention and Control suggest that individuals over the age of 70 years or with underlying cardiovascular disease, cancer, chronic obstructive pulmonary disease, asthma, or diabetes are at increased risk of severe COVID-19. However, the prevalence of these prognostic factors is unknown in many countries. We aimed to describe the burden and prevalence of prognostic factors of severe COVID-19 at national and county level in Sweden. We calculated the burden and prevalence of prognostic factors for severe COVID-19 based on records from the Swedish national health care and population registers for 3 years before 1st January 2016. 9,624,428 individuals were included in the study population. 22.1% had at least one prognostic factor for severe COVID-19 (2,131,319 individuals), and 1.6% had at least three factors (154,746 individuals). The prevalence of underlying medical conditions ranged from 0.8% with chronic obstructive pulmonary disease (78,516 individuals) to 7.4% with cardiovascular disease (708,090 individuals), and the county specific prevalence of at least one prognostic factor ranged from 19.2% in Stockholm (416,988 individuals) to 25.9% in Kalmar (60,005 individuals). We show that one in five individuals in Sweden is at increased risk of severe COVID-19. When compared with the critical care capacity at a local and national level, these results can aid authorities in optimally planning healthcare resources during the current pandemic. Findings can also be applied to underlying assumptions of disease burden in modelling efforts to support COVID-19 planning.

Polyamines treatment during pollen germination and pollen tube elongation in tobacco modulate reactive oxygen species and nitric oxide homeostasis

Several signaling pathways have been shown to be involved in the regulation of pollen germination and pollen tube elongation. Among others, exogenously applied polyamines were found to strongly affect pollen maturation, pollen tube emergence and elongation. In this study, our aim was to investigate the regulatory relation among exogenous polyamines, and endogenous reactive oxygen species and nitric oxide under pollen germination and the apical growth of pollen tube in tobacco plants. We have found that the various polyamines differentially affected the metabolism of nitric oxide and reactive oxygen species during the processes of pollen germination in the grain and the lengthening pollen tube. It is hypothesized that their differential effects might be related to their distinct influence on the endogenous nitric oxide and reactive oxygen species levels.

Predicting the duration of sickness absence spells due to back pain: a population-based study from Sweden

Objectives

We aimed to develop and validate a prediction model for the duration of sickness absence (SA) spells due to back pain (International Statistical Classification of Diseases and Related Health Problems 10th Revision: M54), using Swedish nationwide register microdata.

Methods

Information on all new SA spells >14 days from 1 January 2010 to 30 June 2012 and on possible predictors were obtained. The duration of SA was predicted by using piecewise constant hazard models. Nine predictors were selected for the final model based on a priori decision and log-likelihood loss. The final model was estimated in a random sample of 70% of the SA spells and later validated in the remaining 30%.

Results

Overall, 64 048 SA spells due to back pain were identified during the 2.5 years; 74% lasted ≤90 days, and 9% >365 days. The predictors included in the final model were age, sex, geographical region, employment status, multimorbidity, SA extent at the start of the spell, initiation of SA spell in primary healthcare and number of SA days and specialised outpatient healthcare visits from the preceding year. The overall c-statistic (0.547, 95% CI 0.542 to 0.552) suggested a low discriminatory capacity at the individual level. The c-statistic was 0.643 (95% CI 0.634 to 0.652) to predict >90 days spells, 0.686 (95% CI 0.676 to 0.697) to predict >180 spells and 0.753 (95% CI 0.740 to 0.766) to predict >365 days spells.

Conclusions

The model discriminates SA spells >365 days from shorter SA spells with good discriminatory accuracy.

Alcohol consumption trajectories and self-rated health: findings from the Stockholm Public Health Cohort

OBJECTIVE

To investigate whether poor self-rated health and psychological distress are differentially associated with drinking trajectories over time.

METHODS

From the Stockholm Public Health Cohort, two subcohorts surveyed in 2002-2010-2014 and 2006-2010-2014 (n=23 794 and n=34 667 at baseline, respectively) were used. Alcohol consumption, self-rated health, psychological distress (measured by General Health Questionnaire-12), lifestyle factors and longstanding illness were assessed by questionnaires. Demographic and socioeconomic variables were obtained by register linkage. Logistic regression was fitted to assess the associations with eight alcohol consumption trajectories, which were constructed among 30 228 individuals (13 898 and 16 330 from the 2002 and 2006 subcohorts, respectively) with measures of consumption at three time points.

RESULTS

Compared with stable moderate drinkers, all other trajectories were associated with poor self-rated health with multiadjusted OR for stable non-drinkers of 2.35 (95% CIs 1.86 to 2.97), unstable non-drinkers (OR=2.58, 95% CI 1.54 to 3.32), former drinkers (OR=2.81, 95% CI 2.31 to 3.41) and stable heavy drinkers (OR=2.16, 95% CI 1.47 to 3.20). The associations were not fully explained by sociodemographic and lifestyle factors and longstanding illness. Former drinking, but no other trajectories, was associated with psychological distress (OR=1.24; 95% CI 1.10 to 1.41).

CONCLUSION

We found a U-shape association between alcohol trajectories and self-rated health, but not with psychological distress. Compared with stable moderate drinking, former drinking was associated with the highest odds of both poor self-rated health and psychological distress. The study confirms the importance of a life-course approach to examining the effect of alcohol consumption on health and highlights the poorer general and mental health status of non-drinkers who were former drinkers.

Invasive Procedures Associated With the Development of Infective Endocarditis

BACKGROUND

Various invasive medical procedures might induce bacteremia and, hence, act as triggers for infective endocarditis. However, empirical data in humans on the potential dangers of invasive medical procedures in this regard are very sparse. Due to lack of sufficient data, it is currently debated whether the risk for endocarditis with medical procedures is substantial or rather negligible.

OBJECTIVES

The purpose of this nationwide case-crossover study was to quantify the excess risk for infective endocarditis in association with invasive medical and surgical procedures.

METHODS

The authors identified all adult patients treated for endocarditis in hospitals in Sweden between January 1, 1998, and December 31, 2011. The authors applied a case-crossover design and compared the occurrence of invasive medical procedures 12 weeks before endocarditis with a corresponding 12-week time period exactly 1 year earlier. The authors considered all invasive nondental medical procedures except for those that are likely to be undertaken due to endocarditis or sepsis or due to infections that could possibly lead to endocarditis.

RESULTS

The authors identified 7,013 cases of infective endocarditis during the study period. Among others, several cardiovascular procedures, especially coronary artery bypass grafting; procedures of the skin and management of wounds; transfusion; dialysis; bone marrow puncture; and some endoscopies, particularly bronchoscopy, were strongly associated with an increased risk for infective endocarditis.

CONCLUSIONS

This study suggests that several invasive nondental medical procedures are associated with a markedly increased risk for infective endocarditis.

Moderate alcohol consumption and depression - a longitudinal population-based study in Sweden

BACKGROUND AND AIMS

The interrelationship between alcohol consumption and depression is complex, and the direction of the association is unclear. We investigated whether alcohol consumption influences the risk of depression while accounting for this potential bidirectionality.

METHODS

A total of 10 441 individuals participated in the PART study in 1998-2000, 8622 in 2001-2003, and 5228 in 2010. Participants answered questions on their alcohol consumption, symptoms of depression, childhood adversity, and sociodemographic, socioeconomic, psychosocial, and lifestyle factors. A total of 5087 participants provided repeated information on alcohol consumption. We used marginal structural models to analyze the association between alcohol consumption and depression while controlling for previous alcohol consumption and depressive symptoms and other time-varying confounders.

RESULTS

Non-drinkers had a higher depression risk than light drinkers (≤7 drinks/week) (risk ratio: 1.7; 95% confidence interval 1.3-2.1). Consumers of seven-fourteen drinks/week had a depression risk similar to that of light drinkers. Hazardous drinking was associated with a higher risk of depression than non-hazardous alcohol consumption (risk ratio: 1.8, 95% confidence interval: 1.4-2.4).

CONCLUSION

Light and moderate alcohol consumption and non-hazardous drinking were associated with the lowest risk of subsequent depression after accounting for potential bidirectional effects. Hazardous drinking increased the risk of depression.

A prediction model for duration of sickness absence due to stress-related disorders

BACKGROUND

Stress-related disorders are leading causes of long-term sickness absence (SA) and there is a great need for decision support tools to identify patients with a high risk for long-term SA due to them.

AIMS

To develop a clinically implementable prediction model for the duration of SA due to stress-related disorders.

METHODS

All new SA spells with F43 diagnosis code lasting >14 days and initiated between 2010-01-01 and 2012-06-30 were identified through data from the Social Insurance Agency. Information on baseline predictors was linked on individual level from other nationwide registers. Piecewise-constant hazard regression was used to predict the duration of the SA. Split-sample validation was used to develop and validate the model, and c-statistics and calibration plots to evaluate it.

RESULTS

Overall 83,443 SA spells, belonging to 77,173 individuals were identified. The median SA duration was 55 days (10% were >365 days). Age, sex, geographical region, employment status, educational level, extent of SA at start and SA days, outpatient healthcare visits, and multi-morbidity in the preceding 365 days were selected to the final model. The model was well calibrated. The overall c-statistics was 0.54 (95% confidence intervals: 0.53-0.54) and 0.70 (95% confidence intervals: 0.69-0.71) for predicting SA spells >365 days.

LIMITATIONS

The heterogeneity of the F43-diagnosis and the exclusive use of register-based predictors limited our possibility to increase the discriminatory accuracy of the prediction.

CONCLUSION

The final model could be implementable in clinical settings to predict duration of SA due to stress-related disorders and could satisfyingly discriminate long-term SA.

Light-moderate alcohol consumption and left ventricular function among healthy, middle-aged adults: the HUNT study

OBJECTIVES

To investigate the association between alcohol consumption and left ventricular (LV) function in a population with low average alcohol intake.

DESIGN, SETTING AND PARTICIPANTS

A total of 1296 healthy participants, free from cardiovascular diseases, were randomly selected from the third wave of the Norwegian HUNT study (2006-2008) and underwent echocardiography. After validation of the inclusion criteria, 30 participants were excluded due to arrhythmias or myocardial or valvular pathology. Alcohol consumption, sociodemographic and major cardiovascular risk factors were assessed by questionnaires and clinical examination in the HUNT3. General linear models were used to analyse the cross-sectional associations between alcohol intake and LV indices.

PRIMARY AND SECONDARY OUTCOME MEASURES

LV functional and structural indices were measured with tissue Doppler and speckle tracking echocardiography.

RESULTS

We observed no associations between alcohol consumption and multivariable-adjusted LV functional indices. Excluding abstainers who reported regular alcohol consumption 10 years prior to the baseline did not change the results. Alcohol consumption was positively associated with LV mass indices (p<0.01 for linear trend of the means); there was no such association among participants with non-risky drinking characteristics (p=0.67 for linear trend of the means).

CONCLUSIONS

We found no clear evidence that light-moderate alcohol consumption is associated with measures of LV function, although our results indicate that consumption, especially when marked by binge drinking, is progressively associated with greater LV mass.

Arabidopsis NAP-related proteins (NRPs) contribute to the coordination of plant growth, developmental rate, and age-related pathogen resistance under short days

Plant nucleosome assembly protein-related proteins (NRPs) are histone chaperons involved in nucleosome turnover. Despite this basic cellular function, the Arabidopsis nrp1-1 nrp2-1 knock out mutant has been reported to exhibit only mild seedling root phenotypes and to significantly affect the expression of only few hundred genes Zhu et al. (2006). Here we report that NRP loss-of-function as well as the ectopic overexpression of At NRP1 significantly affected the growth, development, and the pathogen response of Arabidopsis plants under short day conditions. The nrp1-1 nrp2-1 mutant grew faster and flowered weeks earlier than the wild type and the overexpressor. The latter developed slower and flowered at a lower number of leaves than the mutant and the wild type. Moreover, the mutant was more sensitive, the overexpressor was more tolerant to pathogen-induced necrosis correlating with their more adult and juvenile character, respectively. Transcriptomic comparison of mature non-bolting plants agreed with the phenotypes. The presented and other published data indicate that although NRPs might not be absolutely required for normal plant growth and development, their level needs to be controlled to allow the epigenetic coordination of metabolic, growth, defence and developmental processes during the acclimation to unfavourable growth conditions such as short days.

Does Moderate Drinking Increase the Risk of Atrial Fibrillation? The Norwegian HUNT (Nord-Trøndelag Health) Study

BACKGROUND

Compelling evidence suggests that excessive alcohol consumption increases the risk of atrial fibrillation (AF), but the effect of light-moderate alcohol consumption is less certain. We investigated the association between alcohol consumption within recommended limits and AF risk in a light-drinking population.

METHODS AND RESULTS

Among 47 002 participants with information on alcohol consumption in a population-based cohort study in Norway, conducted from October 2006 to June 2008, 1697 validated AF diagnoses were registered during the 8 years of follow-up. We used Cox proportional hazard models with fractional polynomials to analyze the association between alcohol intake and AF. Population attributable risk for drinking within the recommended limit (ie, at most 1 drink per day for women and 2 drinks per day for men without risky drinking) compared with nondrinking was also calculated. The average alcohol intake was 3.8±4.8 g/d. The adjusted hazard ratio for AF was 1.38 (95% confidence interval, 1.06-1.80) when we compared participants consuming >7 drinks per week with abstainers. When we modeled the quantity of alcohol intake as a continuous variable, the risk increased in a curvilinear manner. It was higher with heavier alcohol intake, but there was virtually no association at <1 drink per day for women and <2 drinks per day for men in the absence of risky drinking. The population attributable risk among nonrisky drinkers was 0.07% (95% confidence interval, -0.01% to 0.13%).

CONCLUSIONS

Although alcohol consumption was associated with a curvilinearly increasing risk of AF in general, the attributable risk of alcohol consumption within recommended limits among participants without binge or problem drinking was negligible in this population.

Deregulation of apoplastic polyamine oxidase affects development and salt response of tobacco plants

Polyamine (PA) homeostasis is associated with plant development, growth and responses to biotic/abiotic stresses. Apoplastic PA oxidase (PAO) catalyzes the oxidation of PAs contributing to cellular homeostasis of reactive oxygen species (ROS) and PAs. In tobacco, PAs decrease with plant age, while apoplastic PAO activity increases. Our previous results with young transgenic tobacco plants with enhanced/reduced apoplastic PAO activity (S-ZmPAO/AS-ZmPAO, respectively) established the importance of apoplastic PAO in controlling tolerance to short-term salt stress. However, it remains unclear if the apoplastic PAO pathway is important for salt tolerance at later stages of plant development. In this work, we examined whether apoplastic PAO controls also plant development and tolerance of adult plants during long-term salt stress. The AS-ZmPAO plants contained higher Ca2+ during salt stress, showing also reduced chlorophyll content index (CCI), leaf area and biomass but taller phenotype compared to the wild-type plants during salt. On the contrary, the S-ZmPAO had more leaves with slightly greater size compared to the AS-ZmPAO and higher antioxidant genes/enzyme activities. Accumulation of proline in the roots was evident at prolonged stress and correlated negatively with PAO deregulation as did the transcripts of genes mediating ethylene biosynthesis. In contrast to the strong effect of apoplastic PAO to salt tolerance in young plants described previously, the effect it exerts at later stages of development is rather moderate. However, the different phenotypes observed in plants deregulating PAO reinforce the view that apoplastic PAO exerts multifaceted roles on plant growth and stress responses. Our data suggest that deregulation of the apoplastic PAO can be further examined as a potential approach to breed plants with enhanced/reduced tolerance to abiotic stress with minimal associated trade-offs.

An NADPH-Oxidase/Polyamine Oxidase Feedback Loop Controls Oxidative Burst Under Salinity

The apoplastic polyamine oxidase (PAO) catalyzes the oxidation of the higher polyamines spermidine and spermine, contributing to hydrogen peroxide (H2O2) accumulation. However, it is yet unclear whether apoplastic PAO is part of a network that coordinates the accumulation of reactive oxygen species (ROS) under salinity or if it acts independently. Here, we unravel that NADPH oxidase and apoplastic PAO cooperate to control the accumulation of H2O2 and superoxides (O2·-) in tobacco (Nicotiana tabacum). To examine to what extent apoplastic PAO constitutes part of a ROS-generating network, we examined ROS accumulation in guard cells of plants overexpressing or down-regulating apoplastic PAO (lines S2.2 and A2, respectively) or down-regulating NADPH oxidase (line AS-NtRbohD/F). The H2O2-specific probe benzene sulfonyl-H2O2 showed that, under salinity, H2O2 increased in S2.2 and decreased in A2 compared with the wild type. Surprisingly, the O2·--specific probe benzene sulfonyl-So showed that O2·- levels correlated positively with that of apoplastic PAO (i.e. showed high and low levels in S2.2 and A2, respectively). By using AS-NtRbohD/F lines and a pharmacological approach, we could show that H2O2 and O2·- accumulation at the onset of salinity stress was dependent on NADPH oxidase, indicating that NADPH oxidase is upstream of apoplastic PAO. Our results suggest that NADPH oxidase and the apoplastic PAO form a feed-forward ROS amplification loop, which impinges on oxidative state and culminates in the execution of programmed cell death. We propose that the PAO/NADPH oxidase loop is a central hub in the plethora of responses controlling salt stress tolerance, with potential functions extending beyond stress tolerance.

Alcohol consumption is associated with a lower incidence of acute myocardial infarction: results from a large prospective population-based study in Norway

AIMS

Compelling evidence suggests that light-to-moderate alcohol consumption is associated with a reduced risk of acute myocardial infarction (AMI), but several issues from previous studies remain to be addressed. The aim of this study was to investigate some of these key issues related to the association between alcohol consumption and AMI risk, including the strength and shape of the association in a low-drinking setting, the roles of quantity, frequency and beverage type, the importance of confounding by medical and psychiatric conditions, and the lack of prospective data on previous drinking.

METHODS

A population-based prospective cohort study of 58 827 community-dwelling individuals followed for 11.6 years was conducted. We assessed the quantity and frequency of consumption of beer, wine and spirits at baseline in 1995-1997 and the frequency of alcohol intake approximately 10 years earlier.

RESULTS

A total of 2966 study participants had an AMI during the follow-up period. Light-to-moderate alcohol consumption was inversely and linearly associated with AMI risk. After adjusting for major cardiovascular disease risk factors, the hazard ratio for a one-drink increment in daily consumption was 0.72 (95% confidence interval 0.62-0.86). Accounting for former drinking or comorbidities had almost no effect on the association. Frequency of alcohol consumption was more strongly associated with lower AMI risk than overall quantity consumed.

CONCLUSIONS

Light-to-moderate alcohol consumption was linearly associated with a decreased risk of AMI in a population in which abstaining from alcohol is not socially stigmatized. Our results suggest that frequent alcohol consumption is most cardioprotective and that this association is not driven by misclassification of former drinkers.

Light-to-moderate drinking and incident heart failure--the Norwegian HUNT study

BACKGROUND

We analyzed the association between light-to-moderate alcohol intake and the risk of heart failure (HF).

METHODS AND RESULTS

We studied 60,665 individuals free of HF who provided information on alcohol consumption in a population-based cohort study conducted in 1995-97 in Norway. Sociodemographic factors, cardiovascular risk factors and common chronic disorders were assessed by questionnaires and/or by a clinical examination. The cohort was followed for a first HF event for an average of 11.2 ± 3.0 years. Mean alcohol consumption was 2.95 ± 4.5 g/day; 1588 HF cases occurred during follow-up. The quantity of alcohol consumption was inversely associated with incident HF in this low-drinking population. The risk was lowest for consumption over three but less than six drinks/week; the multivariate hazard ratio when comparing this category to non-drinkers was 0.67 (95% CI: 0.50-0.92). Among problem drinkers based on CAGE questionnaires, total consumption showed no favorable association with HF, even when overall consumption was otherwise moderate. Excluding former drinkers and controlling for common chronic diseases had minimal effect on these associations. Frequent alcohol consumption, i.e. more than five times/month, was associated with the lowest HF risk; the adjusted hazard ratio comparing this group to alcohol intake less than once/month was 0.83 (95% CI: 0.68-1.03). We found no evidence for a differential effect according to beverage type, nor that the competing risks of death from other causes modified the association.

CONCLUSIONS

Frequent light-to-moderate alcohol consumption without problem drinking was associated with a lower HF risk in this population characterized by a low average alcohol intake.

Nitric oxide contributes to copper tolerance by influencing ROS metabolism in Arabidopsis

Nitric oxide improves copper tolerance via modulation of superoxide and hydrogen peroxide levels. This reflects the necessity of a well-coordinated interplay between NO and ROS during stress tolerance. Copper (Cu) excess causes toxicity and one probable consequence of this is the disturbance of cell redox state maintenance, inter alia, by reactive oxygen- (ROS) and nitrogen species (RNS). The objective of this paper was to examine the role of nitric oxide (NO) in Cu stress tolerance and its relationship with ROS in Arabidopsis. In agar-grown seedlings, concentration-dependent Cu accumulation was observed. The 5 μM Cu resulted in reduced cell viability in the NO overproducing nox1 and gsnor1-3 root tips compared to the wild-type (WT). In contrast, 25 and 50 μM Cu caused higher viability in these mutants, while in the NO-lacking nia1nia2 lower viability was detected than in the WT. The exogenous NO donor enhanced cell viability and scavenging endogenous NO decreased it in Cu-exposed WT seedlings. Besides, SNP in nia1nia2 roots led to the improvement of viability. The ascorbic acid-deficient mutants (vtc2-1, vtc2-3) possessing slightly elevated ROS levels proved to be Cu sensitive, while miox4 showing decreased ROS production was more tolerant to Cu than the WT. In nox1 and gsnor1-3, Cu did not induce superoxide formation, and H₂O₂ accumulation occurred only in the case of NO deficiency. Based on these, under mild stress NO intensifies cell injury, while in the case of severe Cu excess it contributes to better viability. ROS were found to be responsible for aggravation of Cu-induced damage. NO alleviates acute Cu stress via modulation of O₂(·-) and H₂O₂ levels reflecting the necessity of a well-coordinated interplay between NO and ROS during stress tolerance.

Physiological and morphological responses of the root system of Indian mustard (Brassica juncea L. Czern.) and rapeseed (Brassica napus L.) to copper stress

Copper (Cu) is an essential microelement for growth and development, but in excess it can cause toxicity in plants. In this comparative study, the uptake and accumulation of Cu as well as the morphological and physiological responses of Indian mustard (Brassica juncea L. Czern.) and rapeseed (Brassica napus L.) roots to Cu treatment were investigated. The possible involvement of redox active molecules (reactive oxygen species and nitric oxide) and modification in cell wall structure associated with Cu-induced morphological responses were also studied. In short- and long-term treatments, B. juncea suffered more pronounced growth inhibition as compared with B. napus. In addition to the shortening of primary and lateral roots, the number and the density of the laterals were also decreased by Cu. Exposure to copper induced nitric oxide generation in the root tips and this event proved to be dependent on the duration of the exposure and on the plant species. In short- and long-term treatments, Indian mustard showed more significant activation of superoxide dismutase (SOD), inhibition of ascorbate peroxidase (APX) and oxidation of ascorbate (AsA) than B. napus. Moreover, H2O2-dependent lignification was also observed in the Cu-exposed plants. In longer term, significant AsA accumulation and callose deposition were observed, reflecting serious oxidative stress in B. juncea. Based on the morphological and physiological results, we conclude that rapeseed tolerates Cu excess better than Indian mustard.

Sublethal concentrations of salicylic acid decrease the formation of reactive oxygen species but maintain an increased nitric oxide production in the root apex of the ethylene-insensitive never ripe tomato mutants

The pattern of salicylic acid (SA)-induced production of reactive oxygen species (ROS) and nitric oxide (NO) were different in the apex of adventitious roots in wild-type and in the ethylene-insensitive never ripe (Nr) mutants of tomato (Solanum lycopersicum L. cv Ailsa Craig). ROS were upregulated, while NO remained at the control level in apical root tissues of wildtype plants exposed to sublethal concentrations of SA. In contrast, Nr plants expressing a defective ethylene receptor displayed a reduced level of RO S and a higher NO content in the apical root cells. In wild-type plants NO production seems to be RO S(H2O2)-dependent at cell death-inducing concentrations of SA, indicating that ROS and NO may interact to trigger oxidative cell death. In the absence of significant RO S accumulation, the increased NO production caused moderate reduction in cell viability in root apex of Nr plants exposed to 10(-3) M SA. This suggests that a functional ethylene signaling pathway is necessary for the control of ROS and NO production induced by SA.

Cross-talk between salicylic acid and NaCl-generated reactive oxygen species and nitric oxide in tomato during acclimation to high salinity

Hydrogen peroxide (H₂O₂) and nitric oxide (NO) generated by salicylic acid (SA) are considered to be functional links of cross-tolerance to various stressors. SA-stimulated pre-adaptation state was beneficial in the acclimation to subsequent salt stress in tomato (Solanum lycopersicum cv. Rio Fuego). At the whole-plant level, SA-induced massive H₂O₂ accumulation only at high concentrations (10⁻³-10⁻² M), which later caused the death of plants. The excess accumulation of H₂O₂ as compared with plants exposed to 100 mM NaCl was not associated with salt stress response after SA pre-treatments. In the root tips, 10⁻³-10⁻² M SA triggered the production of reactive oxygen species (ROS) and NO with a concomitant decline in the cell viability. Sublethal concentrations of SA, however, decreased the effect of salt stress on ROS and NO production in the root apex. The attenuation of oxidative stress because of high salinity occurred not only in pre-adapted plants but also at cell level. When protoplasts prepared from control leaves were exposed to SA in the presence of 100 mM NaCl, the production of NO and ROS was much lower and the viability of the cells was higher than in salt-treated samples. This suggests that, the cross-talk of signalling pathways induced by SA and high salinity may occur at the level of ROS and NO production. Abscisic acid (ABA), polyamines and 1-aminocyclopropane-1-carboxylic acid, the compounds accumulating in pre-treated plants, enhanced the diphenylene iodonium-sensitive ROS and NO levels, but, in contrast to others, ABA and putrescine preserved the viability of protoplasts.

Salicylic acid treatment via the rooting medium interferes with stomatal response, CO2 fixation rate and carbohydrate metabolism in tomato, and decreases harmful effects of subsequent salt stress

Salicylic acid (SA) applied at 10(-3) m in hydroponic culture decreased stomatal conductance (g(s)), maximal CO(2) fixation rate (A(max) ) and initial slopes of the CO(2) (A/C(i)) and light response (A/PPFD) curves, carboxylation efficiency of Rubisco (CE) and photosynthetic quantum efficiency (Q), resulting in the death of tomato plants. However, plants could acclimate to lower concentrations of SA (10(-7) -10(-4) m) and, after 3 weeks, returned to control levels of g(s), photosynthetic performance and soluble sugar content. In response to high salinity (100 mm NaCl), the pre-treated plants exhibited higher A(max) as a function of internal CO(2) concentration (C(i) ) or photosynthetic photon flux density (PPFD), and higher CE and Q values than salt-treated controls, suggesting more effective photosynthesis after SA treatment. Growth in 10(-7) or 10(-4) m SA-containing solution led to accumulation of soluble sugars in both leaf and root tissues, which remained higher in both plant parts during salt stress at 10(-4) m SA. The activity of hexokinase (HXK) with glucose, but not fructose, as substrate was reduced by SA treatment in leaf and root samples, leading to accumulation of glucose and fructose in leaf tissues. HXK activity decreased further under high salinity in both plant organs. The accumulation of soluble sugars and sucrose in roots of plants growing in the presence of 10(-4) m SA contributed to osmotic adjustment and improved tolerance to subsequent salt stress. Apart from its putative role in delaying senescence, decreased HXK activity may divert hexoses from catabolic reactions to osmotic adaptation.

Salicylic acid improves acclimation to salt stress by stimulating abscisic aldehyde oxidase activity and abscisic acid accumulation, and increases Na+ content in leaves without toxicity symptoms in Solanum lycopersicum L

Pre-treatment with 10(-4)M salicylic acid (SA) in hydroponic culture medium provided protection against salinity stress in tomato plants (Solanum lycopersicum L. cv. Rio Fuego). The effect of 10(-7) or 10(-4)M SA on the water status of plants was examined in relation to the biosynthesis and accumulation of abscisic acid (ABA) in order to reveal the role of SA in the subsequent response to salt stress. Both pre-treatments inhibited the K+(86Rb+) uptake of plants, reduced the K+ content of leaves, and caused a decrease in leaf water potential (psi(w)). Due to the changes in the cellular water status, SA triggered the accumulation of ABA. Since the decrease in psi(w) proved to be transient, the effect of SA on ABA synthesis may also develop via other mechanisms. In spite of osmotic adaptation, the application of 10(-4)M, but not 10(-7)M SA, led to prolonged ABA accumulation and to enhanced activity of aldehyde oxidase (AO1, EC.1.2.3.1.), an enzyme responsible for the conversion of ABA-aldehyde to ABA, both in root and leaf tissues. AO2-AO4 isoforms from the root extracts also exhibited increased activities. The fact that the activities of AO are significantly enhanced both in the leaves and roots of plants exposed to 10(-4)M SA, may indicate a positive feedback regulation of ABA synthesis by ABA in this system. Moreover, during a 100mM NaCl treatment, higher levels of free putrescine or spermine were found in these leaves or roots, respectively, than in the salt-stressed controls, suggesting that polyamines may be implicated in the protection response of the cells. As a result, Na+ could be transported to the leaf mesophyll cells without known symptoms of salt toxicity.

Coffee consumption and mortality after acute myocardial infarction: the Stockholm Heart Epidemiology Program

BACKGROUND

Cohort studies have suggested little effect of coffee consumption on risk of acute myocardial infarction. The effect of coffee consumption on prognosis after myocardial infarction is uncertain.

METHODS

In a population-based inception cohort study, we followed 1,369 patients hospitalized with a confirmed first acute myocardial infarction between 1992 and 1994 in Stockholm County, Sweden, as part of the Stockholm Heart Epidemiology Program. Participants reported usual coffee consumption over the preceding year with a standardized questionnaire distributed during hospitalization and underwent a health examination 3 months after discharge. Participants were followed for hospitalizations and mortality with national registers through November 2001.

RESULTS

A total of 289 patients died during follow-up. Compared with intake of <1 cup per day, coffee consumption was inversely associated with mortality, with multivariable-adjusted hazard ratios of 0.68 (95% confidence interval [CI] 0.45-1.02) for 1 to <3 cups, 0.56 (95% CI 0.37-0.85) for 3 to <5 cups, 0.52 (95% CI 0.34-0.83) for 5 to <7 cups, and 0.58 (95% CI 0.34-0.98) for > or =7 cups per day (P trend .06). Coffee intake was not associated with hospitalization for congestive heart failure or stroke. Candidate lipid and inflammatory biomarkers did not appear to account for the observed inverse association with mortality.

CONCLUSIONS

Self-reported coffee consumption at the time of hospitalization for myocardial infarction was inversely associated with subsequent postinfarction mortality in this population with broad coffee intake. If confirmed in other settings, identification of relevant mechanisms could lead to an improved prognosis for survivors of acute myocardial infarction.

Changes in chlorophyll fluorescence parameters and oxidative stress responses of bush bean genotypes for selecting contrasting acclimation strategies under water stress

Drought resistance of bean landraces was compared in order to select genotypes with either high morphological or high biochemical-physiological plasticity. The lines in the former group exhibited fast reduction in fresh and dry mass, decreased the water potential in primary leaves after irrigation withdrawal and the biomass mobilized from the senescent primary leaves was allocated into the roots. These genotypes had high frequency of primary leaf abscission under water stress. The genotypes with plasticity at the biochemical level maintained high water potential and photochemical efficiency, i.e. effective quantum yield, high photochemical (qP) and low non-photochemical (NPQ) quenching in primary leaves under drought stress. While superoxide dismutase activity was not influenced by the drought and the genotype, catalase activity increased significantly in the primary leaves of the genotypes with efficient biochemical adaptation. Lines with high morphological plasticity exhibited higher quaiacol peroxidase activity under drought. Proline may accumulate in both cases, thus it may be a symptom of protein degradation or a successful osmotic adaptation. On the basis of contrasting responses, the genetic material cannot be screened for a large-scale breeding program by a single physiological parameter but by a set of the methods presented in this work.

Effects of long-term salicylic acid pre-treatment on tomato ( Lycopersicon esculentum Mill. L.) salt stress tolerance: Changes in glutathione S-transferase activities and anthocyanin contents

The aim of the present study was to investigate the effect of salicylic acid (SA) pre-treatment on the salt stress acclimation of tomato plants ( Lycopersicon esculentum Mill. L. cv. Rio Fuego). The antioxidant defence and detoxifying capacity of the tissues were analysed by measuring the accumulation of soluble, non-enzymatic antioxidants (anthocyanins) and the activities of glutathione S-transferases (GSTs) at low (10 −7 M) and high (10 −4 M) SA concentrations in plants exposed to 100 mM NaCl. GSTs are a diverse group of enzymes that catalyse the detoxification of xenobiotics and other toxic organic compounds, and anthocyanins are among the few endogenous substrates that bind to GSTs and are sequestered to the vacuole. It was found that 10 −4 M SA pre-treatment improved the acclimation of tomato to high salinity. SA pre-treatments increased the accumulation of anthocyanins both in the presence and absence of 100 mM NaCl. The extractable GST activity of tissues increased under salt stress in young leaves and roots of the control and in plants pre-treated with 10 −4 M SA, while the extractable GST activity in these organs was reduced by 10 −7 M SA. It is suggested that elevated GST activity is a prerequisite for successful acclimation to high salinity in tomato plants pre-treated with SA, but it may also be a symptom of tissue senescence.