Gating small conductance calcium-activated potassium channels in the thalamic reticular nucleus.

Small conductance calcium-activated potassium (SK) channels are well-known regulators of neuronal excitability. In the thalamic hub, SK2 channels act as pacemakers of thalamic reticular neurons, which play a key role in the thalamocortical circuit. Several disease-linked genes are highly enriched in these neurons, including genes known to be associated with schizophrenia and attentional disorders, which could affect neuronal firing. The present study assessed the effect of pharmacological modulation of SK channels in the firing pattern and intrinsic properties of thalamic reticular neurons by performing whole cell patch clamp recordings in brain slices. Two SK positive allosteric modulators and one negative allosteric modulator were used: CyPPA, NS309, and NS8593, respectively. By acting on the burst afterhyperpolarization (AHP), negative modulation of SK channels resulted in increased action potential (AP) firing, increased burst duration, and decreased intervals between bursts. Conversely, both CyPPA and NS309 increased the afterburst AHP, prolonging the interburst interval, which additionally resulted in reduced AP firing in the case of NS309. Alterations in SK channel activity would be expected to alter functioning of thalamocortical circuits. Targeting SK channels could be promising in treating disorders involving thalamic reticular dysfunction such as psychiatric and neurodevelopmental disorders.

Performing up to Nordic principles? Geographic and socioeconomic equity in ambulatory care sensitive conditions among older adults in capital areas of Denmark, Finland and Sweden in 2000-2015.

BACKGROUND: Denmark, Finland and Sweden pursue equity in health for their citizens through universal health care. However, it is unclear if these services reach the older adult population equally across different socioeconomic positions or living areas. Thus, we assessed geographic and socioeconomic equity in primary health care (PHC) performance among the older adults in the capital areas of Denmark (Copenhagen), Finland (Helsinki) and Sweden (Stockholm) in 2000-2015. Hospitalisations for ambulatory care sensitive conditions (ACSC) were applied as a proxy for PHC performance. METHODS: We acquired individual level ACSCs for those aged ≥ 45 in 2000-2015 from national hospitalisation registers. To identify whether the disparities varied by age, we applied three age groups (those aged 45-64, 65-75 and ≥ 75). Socioeconomic disparities in ACSCs were described with incidence rate ratios (IRR) and annual rates by education, income and living-alone; and then analysed with biennial concentration indices by income. Geographic disparities were described with biennial ACSC rates by small areas and analysed with two-level Poisson multilevel models. These models provided small area estimates of IRRs of ACSCs in 2000 and their slopes for development over time, between which Pearson correlations were calculated within each capital area. Finally, these models were adjusted for income to distinguish between geographic and socioeconomic disparities. RESULTS: Copenhagen had the highest IRR of ACSCs among those aged 45-64, and Helsinki among those aged ≥ 75. Over time IRRs decreased among those aged ≥ 45, but only in Helsinki among those aged ≥ 75. All concentration indices slightly favoured the affluent population but in Stockholm were mainly non-significant. Among those aged ≥ 75, Pearson correlations were low in Copenhagen (-0.14; p = 0.424) but high in both Helsinki (-0.74; < 0.001) and Stockholm (-0.62; < 0.001) - with only little change when adjusted for income. Among those aged ≥ 45 the respective correlations were rather similar, except for a strong correlation in Copenhagen (-0.51, 0.001) after income adjustment. CONCLUSIONS: While socioeconomic disparities in PHC performance persisted among older adults in the three Nordic capital areas, geographic disparities narrowed in both Helsinki and Stockholm but persisted in Copenhagen. Our findings suggest that the Danish PHC incorporated the negative effects of socio-economic segregation to a lesser degree.

Phosphodiesterase 1 Bridges Glutamate Inputs with NO- and Dopamine-Induced Cyclic Nucleotide Signals in the Striatum.

The calcium-regulated phosphodiesterase 1 (PDE1) family is highly expressed in the brain, but its functional role in neurones is poorly understood. Using the selective PDE1 inhibitor Lu AF64196 and biosensors for cyclic nucleotides including a novel biosensor for cGMP, we analyzed the effect of PDE1 on cAMP and cGMP in individual neurones in brain slices from male newborn mice. Release of caged NMDA triggered a transient increase of intracellular calcium, which was associated with a decrease in cAMP and cGMP in medium spiny neurones in the striatum. Lu AF64196 alone did not increase neuronal cyclic nucleotide levels, but blocked the NMDA-induced reduction in cyclic nucleotides indicating that this was mediated by calcium-activated PDE1. Similar effects were observed in the prefrontal cortex and the hippocampus. Upon corelease of dopamine and NMDA, PDE1 was shown to down-regulate the D1-receptor mediated increase in cAMP. PDE1 inhibition increased long-term potentiation in rat ventral striatum, showing that PDE1 is implicated in the regulation of synaptic plasticity. Overall, our results show that PDE1 reduces cyclic nucleotide signaling in the context of glutamate and dopamine coincidence. This effect could have a therapeutic value for treating brain disorders related to dysfunctions in dopamine neuromodulation.

Infertility-related stress and the risk of antidepressants prescription in women: a 10-year register study.

STUDY QUESTION: Is the first-time redeemed prescription of antidepressants predicted by the level of infertility-related stress in women seeking ART treatment? SUMMARY ANSWER: Infertility-related stress in the personal and marital domains and general physical stress reactions were significant predictors of a first redeemed prescription of antidepressants after ART treatment in this 10-year follow-up cohort study. WHAT IS KNOWN ALREADY: The literature has found inconsistent findings regarding the association between infertility-related stress and later psychological adjustment in fertility patients. The association between infertility-related stress and later prescription of antidepressants had never been explored in long-term cohort studies. STUDY DESIGN, SIZE, DURATION: All women (n = 1169) who participated in the Copenhagen Cohort Multi-centre Psychosocial Infertility (COMPI) cohort study in the year 2000 (questionnaire data) were linked with the register-based Danish National ART-Couple (DANAC) I cohort, which includes women and their partners having received ART treatment from 1 January 1994 to 30 September 2009. The study population were among other national health and sociodemographic registers further linked with the Danish National Prescription Registry. PARTICIPANTS/MATERIALS, SETTING, METHODS: Women initiating ART treatment were followed until they had redeemed the first prescription of antidepressants or until 31 December 2009. Logistic regression analyses were conducted to test the association between general physical stress reactions and infertility-related stress in the personal, marital and social domains, respectively, and a future redeemed prescription of antidepressants. Age, education level, marital status, number of fertility treatments prior to study inclusion and female infertility diagnosis were included as covariates in the adjusted analyses. Further, the analysis was stratified according to childbirth or no childbirth during follow-up. MAIN RESULTS AND THE ROLE OF CHANCE: The final sample consisted of 1009 women with a mean age of 31.8 years. At study inclusion, women had tried to conceive for an average of 3.45 years. At 10-year follow-up, a total of 13.7% of women had a first redeemed prescription of antidepressant medication. The adjusted odds ratio (OR) showed that high general physical stress predicted the later prescription of antidepressants (adjusted (adj) OR = 2.85, 95% confidence interval (CI) 1.96-4.16). Regarding infertility-related stress domains, high personal stress (adj OR = 2.14, 95% CI 1.46-3.13) and high marital stress (adj OR = 1.80, 95% CI 1.23-2.64) were significantly associated with the later prescription of antidepressants. Social stress was not significantly associated with the future redeemed prescription of antidepressants (adj OR = 1.10, 95% CI 0.76-1.61). Among women not having achieved childbirth during follow-up, the risk of a first-time prescription of antidepressants associated with infertility-specific stress was higher compared to the risk among women having childbirth during follow-up. LIMITATIONS, REASONS FOR CAUTION: This study did not account for potential mediating factors, such as negative life events, which could be associated with the prescription of antidepressants. Second, we are not able to know if these women had sought psychological support during follow-up. Additionally, antidepressants might be prescribed for other health conditions than depressive disorders. WIDER IMPLICATIONS OF THE FINDINGS: Our results suggest that women presenting high infertility-related stress in the personal and marital domains were at higher risk of redeemed first-time prescription of antidepressants after ART, independently of having delivered a child or not after initiation of ART treatment. Women would benefit from an initial screening specifically for high infertility-related stress. The COMPI Fertility Problem Stress Scales can be used by clinical staff in order to identify women in need of psychological support before starting ART treatments. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by the Portuguese Foundation for Science and Technology (FCT) under an individual doctoral grant attributed to the first author (SFRH/BD/103234/2014). The establishment of the DANAC I cohort was funded by Rosa Ebba Hansen's Fund. The COMPI Infertility Cohort project was supported by The Danish Health Insurance Fund (J.nr. 11/097-97), the Else and Mogens Wedell-Wedellsborgs Fund, the manager E. Danielsens and Wife's Fund, the merchant L.F. Foghts Fund, the Jacob Madsen and Wife Olga Madsens Fund. The authors have no conflicts of interest. TRIAL REGISTRATION NUMBER: NA.

The impact of ART on union dissolution: a register-based study in Denmark 1994-2010.

STUDY QUESTION: Are couples initiating ART treatment at higher risk for future union dissolution compared to other couples? SUMMARY ANSWER: There is no effect of ART treatments in future marital dissolution over a period of 16 years when adjusting for all confounders. WHAT IS KNOWN ALREADY: Findings regarding marital stability and infertility treatments have been sparse and controversial. While there is data showing higher divorce rates among women who go through infertility treatments, there is also some evidence of this experience bringing couples closer by forcing them to communicate more and to deal with the surrounding stigma. Using a population-based study and couple-level data, we investigated the extent to which ART treatment increases the risk for divorce/marital dissolution during up to 16 years of follow-up. STUDY DESIGN SIZE, DURATION: Register-based national cohort study including all women registered with ART treatment in Denmark between 1 January 1994 and 30 September 2009 (n = 42 845). Marital/cohabiting status was confirmed by matching these women to partners who they were married to or shared an address with. To account for having a significant relationship at baseline (2 years), marital/cohabiting status was confirmed by accessing this variable before the establishment of the cohort back to 1 January 1992. PARTICIPANTS/MATERIALS, SETTING, METHODS: A comparison group from the background population including five controls per case and matched to female age at baseline was prospectively sampled. Participants could change status during follow-up if they entered ART. The final sample had 148 972 couples, followed until marital dissolution, death of self/spouse, migration or until 31 December 2010. We used Cox regression models adjusting for female and male age, education, marriage, common child at baseline and live-born child during follow-up. MAIN RESULTS AND THE ROLE OF CHANCE: At baseline, the majority of couples were married (69%). More non-ART couples opted for marriage (70% versus 64%; P < 0.0001) and already had common children at study entry (43% versus 9%; P < 0.0001). During the 16 years of follow-up the majority of couples had children with their baseline partners (56% non-ART versus 65% ART), and 22% ended up separated or divorced (20% ART versus 22% non-ART). Findings revealed a lower risk of break-up among ART couples (crude HR 0.84, 95% CI 0.82-0.86), even after adjusting for both partners' age, education, partnership status and having a common child at baseline (adj HR 0.83, 95% CI 0.80-0.86). However, when subsequent common children (time-dependent) was added to the model, no difference in the risk of dissolution was found (adj HR 1.00, 95% CI 0.99-1.01). A significant interaction between ART status and common children showed that the risk of break-up was attributed to childlessness regardless of having gone through ART treatment. LIMITATIONS REASON FOR CAUTION: This study did not control for involuntary childlessness, non-ART fertility care (ovulation induction, IUI) and biological parenthood. Additionally, there are important predictors of divorce that were not considered. We were unable to adjust for religion, existence of previous marital relationships, income, employment, health status of parents and child(ren), and quality of relationship. WIDER IMPLICATION OF FINDINGS: The finding that going through ART does not increase the risk of break up per se is reassuring for couples who underwent ART and have children or are contemplating to start ART. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by FCT (Portuguese Foundation for Science and Technology), grant ref. SFRH/BPD/85789/2012. The authors have no conflicts of interest. TRIAL REGISTRATION NUMBER: N/A.

A small molecule activator of Nav 1.1 channels increases fast-spiking interneuron excitability and GABAergic transmission in vitro and has anti-convulsive effects in vivo.

Nav 1.1 (SCN1A) channels primarily located in gamma-aminobutyric acid (GABA)ergic fast-spiking interneurons are pivotal for action potential generation and propagation in these neurons. Inappropriate function of fast-spiking interneurons, leading to disinhibition of pyramidal cells and network desynchronization, correlates with decreased cognitive capability. Further, reduced functionality of Nav 1.1 channels is linked to various diseases in the central nervous system. There is, at present, however no subtype selective pharmacological activators of Nav 1.1 channels available for studying pharmacological modulation of interneuron function. In the current study, we identified a small molecule Nav 1.1 activator, 3-amino-5-(4-methoxyphenyl)thiophene-2-carboxamide, named AA43279, and provided an in vitro to in vivo characterization of the compound. In HEK-293 cells expressing human Nav 1.1 channels, AA43279 increased the Nav 1.1-mediated current in a concentration-dependent manner mainly by impairing the fast inactivation kinetics of the channels. In rat hippocampal brain slices, AA43279 increased the firing activity of parvalbumin-expressing, fast-spiking GABAergic interneurons and increased the spontaneous inhibitory post-synaptic currents (sIPSCs) recorded from pyramidal neurons. When tested in vivo, AA43279 had anti-convulsive properties in the maximal electroshock seizure threshold test. AA43279 was tested for off-target effects on 72 different proteins, including Nav 1.2, Nav 1.4, Nav 1.5, Nav 1.6 and Nav 1.7 and exhibited reasonable selectivity. Taken together, AA43279 might constitute a valuable tool compound for revealing biological functions of Nav 1.1 channels.

Job mobility and health in the Danish workforce.

AIMS: The globalized economy has stimulated mobility in the labour market in many countries and Denmark has one of the highest rates of mobility between workplaces among the OECD countries. This raises the question of the potential health effects of mobility and the effect of disease on mobility. METHODS: This study was register-based with a longitudinal design using data on the entire Danish population in 1992-2006. The data included mobility between employers and workplaces and seven different diseases based on admissions to hospital and drug prescriptions. RESULTS: After adjusting for relevant confounders, an exposure-response relationship was seen between mobility and the incidence of ischaemic heart disease, stroke, duodenal ulcer, anxiety/depression and, most strongly, with alcohol-related disorders. The effects were not very strong, however, with odds ratios varying from 1.2 to 1.6. As expected, no effect was seen for colorectal cancer. We also found an effect of both somatic and mental disorders on mobility, but not for the two cancer types. Mobility did not seem to prevent being out of the labour force after diagnosis. CONCLUSIONS: Frequent mobility in the labour market increases the risk of cardiovascular disease, common mental disorders and alcohol-related disorders and these diagnoses also seem to increase the risk of subsequent mobility.

Quantification of the functional expression of the Ca2+ -activated K+ channel KCa 3.1 on microglia from adult human neocortical tissue.

The KCa 3.1 channel (KCNN4) is an important modulator of microglia responses in rodents, but no information exists on functional expression on microglia from human adults. We isolated and cultured microglia (max 1% astrocytes, no neurons or oligodendrocytes) from neocortex surgically removed from epilepsy patients and employed electrophysiological whole-cell measurements and selective pharmacological tools to elucidate functional expression of KCa 3.1. The channel expression was demonstrated as a significant increase in the voltage-independent current by NS309, a KCa 3.1/KCa 2 activator, followed by full inhibition upon co-application with NS6180, a highly selective KCa 3.1 inhibitor. A major fraction (79%) of unstimulated human microglia expressed KCa 3.1, and the difference in current between full activation and inhibition (ΔKCa 3.1) was estimated at 292 ± 48 pA at -40 mV (n = 75), which equals at least 585 channels per cell. Serial KCa 3.1 activation/inhibition significantly hyperpolarized/depolarized the membrane potential. The isolated human microglia were potently activated by lipopolysaccharide (LPS) shown as a prominent increase in TNF-α production. However, incubation with LPS neither changed the KCa 3.1 current nor the fraction of KCa 3.1 expressing cells. In contrast, the anti-inflammatory cytokine IL-4 slightly increased the KCa 3.1 current per cell, but as the membrane area also increased, there was no significant change in channel density. A large fraction of the microglia also expressed a voltage-dependent current sensitive to the KCa 1.1 modulators NS1619 and Paxilline and an inward-rectifying current with the characteristics of a Kir channel. The high functional expression of KCa 3.1 in microglia from epilepsy patients accentuates the need for further investigations of its role in neuropathological processes. GLIA 2016;64:2065-2078.

Are repeated assisted reproductive technology treatments and an unsuccessful outcome risk factors for unipolar depression in infertile women?

INTRODUCTION: Previous studies have shown conflicting results as to whether unsuccessful medically assisted reproduction is a risk factor for depression among women. This study therefore investigated if women with no live birth after assisted reproductive technology (ART) treatment had a higher risk of unipolar depression compared with women with a live birth after ART treatment. MATERIAL AND METHODS: The Danish National ART-Couple (DANAC) Cohort is a national register-based cohort study that consists of women who received ART treatment from 1 January 1994 to 30 September 2009, in Denmark (n = 41 050). Information on unipolar depression was obtained from the Danish Psychiatric Central Research Register. The analyses were conducted in Cox regression analysis. RESULTS: During the 308 494 person-years of follow up, 552 women were diagnosed with unipolar depression. A Cox proportional hazards model showed that women in ART treatment, with no live birth yet, had a lower risk of unipolar depression compared with women with a live birth. Women had the highest risk of unipolar depression 0-42 days after a live birth (adjusted hazard ratio 5.08, 95% CI 3.11-8.29) compared with women with no live birth. A lower, but still increased, risk of unipolar depression, was found in women 43 days to 1 year and >1 year after a live birth compared with women with no live birth yet. CONCLUSIONS: Motherhood is an important trigger of unipolar depression in women conceiving after ART treatment.

Assisted reproductive technology treatment in women with severe eating disorders: a national cohort study.

INTRODUCTION: This national retrospective cohort study investigates the prevalence of women with severe eating disorders in assisted reproductive technology (ART) treatment compared with an age-matched background population without ART treatment. It assesses the frequency distribution of the first and last eating disorder diagnosis before, during, and after ART treatment, and evaluates differences in obstetric outcomes between women with and without a severe eating disorder. MATERIAL AND METHODS: Hospital-diagnosed eating disorders among 42,915 women in the Danish National ART cohort (DANAC), registered during 1994-2009 in the mandatory Psychiatric Central Research Register, were compared with a non-eating disorder ART cohort of 42,644 women and an age-matched background population of 215,290 women without a history of ART treatment for the main outcome measures prevalence of eating disorders, frequency distribution of diagnoses before/during/after ART treatment, as well as ART treatment and obstetric outcomes. RESULTS: In the ART cohort, 271 women (0.63%) had an eating disorder diagnosis compared with 0.73% in the background population (p = 0.025). The prevalence of ovulatory disorder was significantly higher in women with a severe eating disorder compared with the ART cohort without eating disorders. Obstetric outcomes were similar in ART-treated women with and without an eating disorder. CONCLUSION: Women with severe eating disorders were identified in the ART cohort, although significantly less often than in the age-matched background population. Women with severe eating disorders suffered more often from anovulatory infertility than the ART comparison cohort without this disease. Obstetric outcomes appeared reassuring in the ART cohort with eating disorders.

NS19504: a novel BK channel activator with relaxing effect on bladder smooth muscle spontaneous phasic contractions.

Large-conductance Ca(2+)-activated K(+) channels (BK, KCa1.1, MaxiK) are important regulators of urinary bladder function and may be an attractive therapeutic target in bladder disorders. In this study, we established a high-throughput fluorometric imaging plate reader-based screening assay for BK channel activators and identified a small-molecule positive modulator, NS19504 (5-[(4-bromophenyl)methyl]-1,3-thiazol-2-amine), which activated the BK channel with an EC50 value of 11.0 ± 1.4 µM. Hit validation was performed using high-throughput electrophysiology (QPatch), and further characterization was achieved in manual whole-cell and inside-out patch-clamp studies in human embryonic kidney 293 cells expressing hBK channels: NS19504 caused distinct activation from a concentration of 0.3 and 10 µM NS19504 left-shifted the voltage activation curve by 60 mV. Furthermore, whole-cell recording showed that NS19504 activated BK channels in native smooth muscle cells from guinea pig urinary bladder. In guinea pig urinary bladder strips, NS19504 (1 µM) reduced spontaneous phasic contractions, an effect that was significantly inhibited by the specific BK channel blocker iberiotoxin. In contrast, NS19504 (1 µM) only modestly inhibited nerve-evoked contractions and had no effect on contractions induced by a high K(+) concentration consistent with a K(+) channel-mediated action. Collectively, these results show that NS19504 is a positive modulator of BK channels and provide support for the role of BK channels in urinary bladder function. The pharmacologic profile of NS19504 indicates that this compound may have the potential to reduce nonvoiding contractions associated with spontaneous bladder overactivity while having a minimal effect on normal voiding.

Relationship between cumulative exposure to occupational lifting throughout working life and risk of ischemic heart disease in men and women. The Copenhagen Aging and Midlife Biobank.

Ischemic heart disease (IHD) causes mortality and morbidity. High levels of occupational physical activity (OPA) increases IHD risk, and occupational lifting (OL) is suggested as a detrimental OPA exposure. This study investigated the association between accumulated OL throughout working life, and risk for IHD, and potential sex and hypertension differences. Data from Copenhagen Ageing and Midlife Biobank linked to register-based information on incident IHD during 9 years follow-up in the Danish National Patient Registry were included. The outcome was the odds of IHD from baseline (2009-2011) to end of follow-up (2018), among participants without IHD at baseline. Accumulated OL was assessed by linking occupational codes to a Job Exposure Matrix, creating a measure in ton-years (lifting 1,000 kg/day/year). Multivariable logistic regression tested associations between level of accumulated OL and IHD, among the 6,606 included individuals (68% men). During follow-up, 7.3% men and 3.6% women were hospitalized with IHD. Among all participants, the odds for IHD were 47% (OR 1.47, 95% CI 1.05-2.06) higher among those with ≥5 to <10 ton-years, 39% (OR 1.39, 95% CI 1.06-1.83) higher among those with ≥10 to <30 ton-years, and 62% (OR 1.62, 95% CI 1.18-2.22) higher among those with ≥30 ton-years, compared to no accumulated OL. However, these increased odds were in the same direction in the fully-adjusted model but statistically insignificant, ≥5 to <10 ton-years OR 1.28, 95% CI 0.88-1.88; ≥10 to <30 ton-years OR 1.20, 95% CI 0.85-1.69; and ≥30 ton-years OR 1.22, 95% CI 0.81-1.84. No statistically significant interactions, nor any associations, between OL and sex, or hypertension were seen.

Influence of the COVID-19 pandemic on births and induced abortions in Southern Sweden: a register-based study.

BACKGROUND: Pandemics are linked with declining birth rates, but little is known about how the COVID-19 pandemic has influenced childbearing decisions. We aimed to investigate the associations between the COVID-19 pandemic and reproductive decisions, specifically to identify potential changes in the frequency of deliveries and induced abortions in Skåne, Sweden. METHODS: Using the Skåne Healthcare Register, we identified women aged 15-45 years who had at least one pregnancy-related care visit registered between 1 January 2013 and 11 November 11 2021. Deliveries and induced abortions were identified, and changes in weekly delivery and abortion counts were assessed using an interrupted time series design. Relative risks (RRs) and 95% confidence intervals (CIs) were estimated from a Poisson regression model. RESULTS: During the study period we identified 129 131 deliveries and 38 591 abortions. Compared with the counterfactual (exposed interval assuming COVID-19 had not occurred), pandemic exposure was associated with fewer deliveries (RR 0.93; 95% CI 0.89 to 0.98). For abortions, pandemic exposure appeared to be associated with fewer abortions (RR 0.95; 95% CI 0.90 to 1.00); however, age-related differences were found. Among women aged 25 years and over, pandemic exposure was more strongly associated with fewer abortions. Contrastingly, among women aged under 25 years, abortions appeared to increase. CONCLUSIONS: The COVID-19 pandemic seemed to have contributed to a decline in births in Southern Sweden. During the same period, abortions declined in women in the older age range, but contrastingly increased among younger women.

Inverse probability weighting for self-selection bias correction in the investigation of social inequality in mortality.

BACKGROUND: Empirical evaluation of inverse probability weighting (IPW) for self-selection bias correction is inaccessible without the full source population. We aimed to: (i) investigate how self-selection biases frequency and association measures and (ii) assess self-selection bias correction using IPW in a cohort with register linkage. METHODS: The source population included 17 936 individuals invited to the Copenhagen Aging and Midlife Biobank during 2009-11 (ages 49-63 years). Participants counted 7185 (40.1%). Register data were obtained for every invited person from 7 years before invitation to the end of 2020. The association between education and mortality was estimated using Cox regression models among participants, IPW participants and the source population. RESULTS: Participants had higher socioeconomic position and fewer hospital contacts before baseline than the source population. Frequency measures of participants approached those of the source population after IPW. Compared with primary/lower secondary education, upper secondary, short tertiary, bachelor and master/doctoral were associated with reduced risk of death among participants (adjusted hazard ratio [95% CI]: 0.60 [0.46; 0.77], 0.68 [0.42; 1.11], 0.37 [0.25; 0.54], 0.28 [0.18; 0.46], respectively). IPW changed the estimates marginally (0.59 [0.45; 0.77], 0.57 [0.34; 0.93], 0.34 [0.23; 0.50], 0.24 [0.15; 0.39]) but not only towards those of the source population (0.57 [0.51; 0.64], 0.43 [0.32; 0.60], 0.38 [0.32; 0.47], 0.22 [0.16; 0.29]). CONCLUSIONS: Frequency measures of study participants may not reflect the source population in the presence of self-selection, but the impact on association measures can be limited. IPW may be useful for (self-)selection bias correction, but the returned results can still reflect residual or other biases and random errors.

Evidence for a common pharmacological interaction site on K(Ca)2 channels providing both selective activation and selective inhibition of the human K(Ca)2.1 subtype.

We have previously identified Ser293 in transmembrane segment 5 as a determinant for selective K(Ca)2.1 channel activation by GW542573X (4-(2-methoxyphenylcarbamoyloxymethyl)-piperidine-1-carboxylic acid tert-butyl ester). Now we show that Ser293 mediates both activation and inhibition of K(Ca)2.1: CM-TPMF (N-{7-[1-(4-chloro-2-methylphenoxy)ethyl]-[1,2,4]triazolo[1,5-a]pyrimidin-2-yl}-N'-methoxy-formamidine) and B-TPMF (N-{7-[1-(4-tert-butyl-phenoxy)ethyl]-[1,2,4]triazolo[1,5-a]pyrimidin-2-yl}-N'-methoxy-formamidine), two newly identified and structurally related [1,2,4]triazolo[1,5-a]pyrimidines, act either as activators or as inhibitors of the human K(Ca)2.1 channel. Whereas (-)-CM-TPMF activates K(Ca)2.1 with an EC(50) value of 24 nM, (-)-B-TPMF inhibits the channel with an IC(50) value of 31 nM. In contrast, their (+)-enantiomers are 40 to 100 times less active. Both (-)-CM-TPMF and (-)-B-TPMF are subtype-selective, with 10- to 20-fold discrimination toward other K(Ca)2 channels and the K(Ca)3 channel. Coapplication experiments reveal competitive-like functional interactions between the effects of (-)-CM-TPMF and (-)-B-TPMF. Despite belonging to a different chemical class than GW542573X, the K(Ca)2.1 selectivity of (-)-CM-TPMF and (-)-B-TPMF depend critically on Ser293 as revealed by loss- and gain-of-function mutations. We conclude that compounds occupying the TPMF site may either positively or negatively influence the gating process depending on their substitution patterns. It is noteworthy that (-)-CM-TPMF is 10 times more potent on K(Ca)2.1 than NS309 (6,7-dichloro-1H-indole-2,3-dione 3-oxime), an unselective but hitherto the most potent K(Ca)3/K(Ca)2 channel activator. (-)-B-TPMF is the first small-molecule inhibitor with significant selectivity among the K(Ca)2 channel subtypes. In contrast to peptide blockers such as apamin and scyllatoxin, which preferentially affect K(Ca)2.2, (-)-B-TPMF exhibits K(Ca)2.1 selectivity. These high-affinity compounds, which exert opposite effects on K(Ca)2.1 gating, may help define physiological or pathophysiological roles of this channel.

Negative gating modulation by (R)-N-(benzimidazol-2-yl)-1,2,3,4-tetrahydro-1-naphthylamine (NS8593) depends on residues in the inner pore vestibule: pharmacological evidence of deep-pore gating of K(Ca)2 channels.

Acting as a negative gating modulator, (R)-N-(benzimidazol-2-yl)-1,2,3,4-tetrahydro-1-naphthylamine (NS8593) shifts the apparent Ca(2+)-dependence of the small-conductance Ca(2+)-activated K(+) channels K(Ca)2.1-2.3 to higher Ca(2+) concentrations. Similar to the positive K(Ca) channel-gating modulators 1-ethyl-2-benzimidazolinone (1-EBIO) and cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methylpyrimidin-4-yl]-amine (CyPPA), the binding site for NS8593 has been assumed to be located in the C-terminal region, in which these channels interact with their Ca(2+) sensor calmodulin. However, by using a progressive chimeric approach, we were able to localize the site-of-action of NS8593 to the K(Ca)2 pore. For example, when we transferred the C terminus from the NS8593-insensitive intermediate-conductance K(Ca)3.1 channel to K(Ca)2.3, the chimeric channel remained as sensitive to NS8593 as wild-type K(Ca)2.3. In contrast, when we transferred the K(Ca)2.3 pore to K(Ca)3.1, the channel became sensitive to NS8593. Using site-directed mutagenesis, we subsequently identified two specific residues in the inner vestibule of K(Ca)2.3 (Ser507 and Ala532) that determined the effect of NS8593. Mutation of these residues to the corresponding residues in K(Ca)3.1 (Thr250 and Val275) made K(Ca)2.3 insensitive to NS8593, whereas introduction of serine and alanine into K(Ca)3.1 was sufficient to render this channel highly sensitive to NS8593. It is noteworthy that the same two residue positions have been found previously to mediate sensitivity of K(Ca)3.1 to clotrimazole and 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34). The location of Ser507 in the pore-loop near the selectivity filter and Ala532 in an adjacent position in S6 are within the region predicted to contain the K(Ca)2 channel gate. Hence, we propose that NS8593-mediated gating modulation occurs via interaction with gating structures at a position deep within the inner pore vestibule.

ROS activate KCl cotransport in nonadherent Ehrlich ascites cells but K+ and Cl- channels in adherent Ehrlich Lettré and NIH3T3 cells.

Addition of H(2)O(2) (0.5 mM) to Ehrlich ascites tumor cells under isotonic conditions results in a substantial (22 +/- 1%) reduction in cell volume within 25 min. The cell shrinkage is paralleled by net loss of K(+), which was significant within 8 min, whereas no concomitant increase in the K(+) or Cl(-) conductances could be observed. The H(2)O(2)-induced cell shrinkage was unaffected by the presence of clofilium and clotrimazole, which blocks volume-sensitive and Ca(2+)-activated K(+) channels, respectively, and is unaffected by a raise in extracellular K(+) concentration to a value that eliminates the electrochemical driving force for K(+). On the other hand, the H(2)O(2)-induced cell shrinkage was impaired in the presence of the KCl cotransport inhibitor (dihydro-indenyl)oxyalkanoic acid (DIOA), following substitution of NO(3)(-) for Cl(-), and when the driving force for KCl cotransport was omitted. It is suggested that H(2)O(2) activates electroneutral KCl cotransport in Ehrlich ascites tumor cells and not K(+) and Cl(-) channels. Addition of H(2)O(2) to hypotonically exposed cells accelerates the regulatory volume decrease and the concomitant net loss of K(+), whereas no additional increase in the K(+) and Cl(-) conductance was observed. The effect of H(2)O(2) on cell volume was blocked by the serine-threonine phosphatase inhibitor calyculin A, indicating an important role of serine-threonine phosphorylation in the H(2)O(2)-mediated activation of KCl cotransport in Ehrlich cells. In contrast, addition of H(2)O(2) to adherent cells, e.g., Ehrlich Lettré ascites cells, a subtype of the Ehrlich ascites tumor cells, and NIH3T3 mouse fibroblasts increased the K(+) and Cl(-) conductances after hypotonic cell swelling. Hence, H(2)O(2) induces KCl cotransport or K(+) and Cl(-) channels in nonadherent and adherent cells, respectively.

Selective activation of the SK1 subtype of human small-conductance Ca2+-activated K+ channels by 4-(2-methoxyphenylcarbamoyloxymethyl)-piperidine-1-carboxylic acid tert-butyl ester (GW542573X) is dependent on serine 293 in the S5 segment.

A new small molecule, 4-(2-methoxy-phenylcarbamoyloxymethyl)-piperidine-1-carboxylic acid tert-butyl ester (GW542573X), is presented as an activator of small-conductance Ca(2+)-activated K(+) (SK, K(Ca)2) channels and distinguished from previously published positive modulators of SK channels, such as 1-ethyl-2-benzimidazolinone (1-EBIO) and cyclohexyl-[2-(3,5-dimethylpyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine (CyPPA), in several aspects. GW542573X is the first SK1-selective compound described: an EC(50) value of 8.2 +/- 0.8 microM (n = 6, [Ca(2+)](i) = 200 nM) was obtained from inside-out patches excised from hSK1-expressing HEK293 cells. Whole-cell experiments showed that hSK2 and hSK3 channels were more than 10 times, and hIK channels even more than 100 times, less sensitive to GW542573X. The Ca(2+)-response curve of hSK1 was left-shifted from an EC(50)(Ca(2+)) value of 410 +/- 20 nM (n = 9) to 240 +/- 10 nM (n = 5) in the presence of 10 microM GW542573X. In addition to this positive modulation, GW542573X activated SK1 in the absence of Ca(2+) and furthermore induced a 15% increase in the maximal current at saturating Ca(2+). Thus, GW542573X also acts as a genuine opener of the hSK1 channels, a mechanism of action (MOA) not previously obtained with SK channels. The differential potency on hSK1 and hSK3 enabled a chimera approach to elucidate site(s) important for this new MOA and selectivity property. A single amino acid (Ser293) located in S5 of hSK1 was essential, and substituting the corresponding Leu476 in hSK3 with serine conferred hSK1-like potency (EC(50) = 9.3 +/- 1.4 microM, n = 5). GW542573X may activate SK channels via interaction with "deep-pore" gating structures at the inner pore vestibule or the selectivity filter in contrast to 1-EBIO and CyPPA that exert positive modulation via the intracellular calmodulin binding domain.

Tuning the excitability of midbrain dopamine neurons by modulating the Ca2+ sensitivity of SK channels.

Small conductance Ca(2+) -activated K(+) (SK) channels play a prominent role in modulating the spontaneous activity of dopamine (DA) neurons as well as their response to synaptically-released glutamate. SK channel gating is dependent on Ca(2+) binding to constitutively bound calmodulin, which itself is subject to endogenous and exogenous modulation. In the present study, patch-clamp recording techniques were used to examine the relationship between the apparent Ca(2+) affinity of cloned SK3 channels expressed in cultured human embryonic kidney 293 cells and the excitability of DA neurons in slices from rat substantia nigra using the positive and negative SK channel modulators, 6,7-dichloro-1H-indole-2,3-dione-3-oxime and R-N-(benzimidazol-2-yl)-1,2,3,4-tetrohydro-1-naphtylamine. Increasing the apparent Ca(2+) affinity of SK channels decreased the responsiveness of DA neurons to depolarizing current pulses, enhanced spike frequency adaptation and slowed spontaneous firing, effects attributable to an increase in the amplitude and duration of an apamin-sensitive afterhyperpolarization. In contrast, decreasing the apparent Ca(2+) affinity of SK channels enhanced DA neuronal excitability and changed the firing pattern from a pacemaker to an irregular or bursting discharge. Both the reduction in apparent Ca(2+) affinity and the bursting associated with negative SK channel modulation were gradually surmounted by co-application of the positive SK channel modulator. These results underscore the importance of SK channels in 'tuning' the excitability of DA neurons and demonstrate that gating modulation, in a manner analogous to physiological regulation of SK channels in vivo, represents a means of altering the response of DA neurons to membrane depolarization.