The KCNQ1 potassium channel is down-regulated by ubiquitylating enzymes of the Nedd4/Nedd4-like family

Objective: The voltage-gated KCNQ1 potassium channel regulates key physiological functions in a number of tissues. In the heart, KCNQ1 α-subunits assemble with KCNE1 β-subunits forming a channel complex constituting the delayed rectifier current IKs. In epithelia, KCNQ1 channels participate in controlling body electrolyte homeostasis. Several regulatory mechanisms of the KCNQ1 channel complexes have been reported, including protein kinase A (PKA)-phosphorylation and β-subunit interactions. However, the mechanisms controlling the membrane density of KCNQ1 channels have attracted less attention. Methods and results: Here we demonstrate that KCNQ1 proteins expressed in HEK293 cells are down-regulated by Nedd4/Nedd4-like ubiquitin-protein ligases. KCNQ1 and KCNQ1/KCNE1 currents were reduced upon co-expression of Nedd4-2, the isoform among the nine members of the Nedd4/Nedd4-like family displaying the highest expression level in human heart. In vivo expression of a catalytically inactive form of Nedd4-2, able to antagonize endogenous Nedd4-2 in guinea-pig cardiomyocytes, increased IKs significantly, but did not modify IK1. Concomitant with the reduction in current induced by Nedd4-2, an increased ubiquitylation as well as a decreased total level of KCNQ1 proteins were observed in HEK293 cells. Pull-down and co-immunoprecipitation experiments showed that Nedd4-2 interacts with the C-terminal part of KCNQ1. The Nedd4/Nedd4-like-mediated regulation of the KCNQ1 channel complexes is strictly dependent on a PY motif located in the distal part of the C-terminal domain. When this motif was mutated, the current and ubiquitylation levels were unaffected by Nedd4-2, and Nedd4-2 proteins were neither pulled-down nor co-immunoprecipitated. Conclusions: These results suggest that KCNQ1 internalization and stability is physiologically regulated by its Nedd4/Nedd4-like-dependent ubiquitylation. This mechanism may thereby be important in regulating the surface density of the KCNQ1 channels in cardiomyocytes and other cell type

Time trends in incidence and prevalence of chronic pancreatitis:A 25-year population-based nationwide study

BACKGROUND: Updated population‐based estimates on incidence and prevalence of chronic pancreatitis are scarce. METHODS: We used nationwide healthcare registries to identify all Danish patients diagnosed with chronic pancreatitis and computed crude and standardised incidence rates and prevalence estimates in 1994–2018. Incidence and prevalence were evaluated in relation to patients age and gender, aetiology (alcoholic vs. non‐alcoholic) and smoking and alcohol consumption in the general Danish population. RESULTS: The mean incidence rate of chronic pancreatitis during the study period was 12.6 per 100,000 person years for the total population, for women it was 8.6 per 100,000 person years and for men it was 16.7 per 100,000 person years. The standardised incidence rate was stable from 1994 to 2018, remaining at 12.5 per 100,000 person years in the last observation period (2014–2018). The point prevalence of chronic pancreatitis in 2016 was 153.9 per 100,000 persons. A gradual increase in standardised prevalence estimates was observed during the study period from 126.6 in 1996 to 153.9 in 2016. The mean age at chronic pancreatitis diagnosis increased from 52.1 to 60.0 years during the study period. CONCLUSION: The prevalence of chronic pancreatitis is increasing in the Danish population despite a stable incidence level. Improved management strategies and changes in the underlying patient population may explain these observations

The cortical responses to evoked clinical pain in patients with hip osteoarthritis

BACKGROUND: Experimental models have been used extensively to evaluate pain using e.g., visual analogue scales or electroencephalography (EEG). Stimulation using tonic pain has been shown to better mimic the unpleasantness of chronic pain, but has mainly been evoked by non-clinical stimuli. This study aims to, evaluate the EEG during clinical pain in patients scheduled for total hip replacement with control and resting conditions.METHODS: The hip scheduled for replacement was moved by the examiner to evoke pain for 30 seconds while recording EEG. The control condition entailed movement of the opposite hip in a similar fashion and holding it for 30 seconds. In addition, EEG was recorded during the resting condition with open eyes. The relative spectral content was calculated from the EEG as well as functional connectivity using phase-lag index for frequency bands delta (1-4Hz), theta (4-8Hz), alpha (8-12Hz) and beta (12-32Hz). A mixed model was used for statistical comparison between the three recording conditions.RESULTS: Spectral content differed between conditions in all bands. Functional connectivity differed in delta and theta frequency bands. Post-hoc analysis revealed differences between the painful and control condition in delta, theta and beta for spectral content. Pain during the hip rotation was correlated to the theta (r = -0.24 P = 0.03) and beta (r = 0.25 P = 0.02) content in the EEG.CONCLUSION: EEG differences during hip movements in the affected and unaffected hip appeared in the spectral beta and theta content. This was correlated to the reported pain perceived, pointing towards pain specific brain activity related to clinical pain.</p

The cortical responses to evoked clinical pain in patients with hip osteoarthritis

Experimental models have been used extensively to evaluate pain using e.g., visual analogue scales or electroencephalography (EEG). Stimulation using tonic pain has been shown to better mimic the unpleasantness of chronic pain, but has mainly been evoked by non-clinical stimuli. This study aims to, evaluate the EEG during clinical pain in patients scheduled for total hip replacement with control and resting conditions.The hip scheduled for replacement was moved by the examiner to evoke pain for 30 seconds while recording EEG. The control condition entailed movement of the opposite hip in a similar fashion and holding it for 30 seconds. In addition, EEG was recorded during the resting condition with open eyes. The relative spectral content was calculated from the EEG as well as functional connectivity using phase-lag index for frequency bands delta (1-4Hz), theta (4-8Hz), alpha (8-12Hz) and beta (12-32Hz). A mixed model was used for statistical comparison between the three recording conditions.Spectral content differed between conditions in all bands. Functional connectivity differed in delta and theta frequency bands. Post-hoc analysis revealed differences between the painful and control condition in delta, theta and beta for spectral content. Pain during the hip rotation was correlated to the theta (r = -0.24 P = 0.03) and beta (r = 0.25 P = 0.02) content in the EEG.EEG differences during hip movements in the affected and unaffected hip appeared in the spectral beta and theta content. This was correlated to the reported pain perceived, pointing towards pain specific brain activity related to clinical pain

Regional gastrointestinal transit times in patients with chronic pancreatitis

The mechanisms behind disrupted gastrointestinal (GI) motor function in patients with chronic pancreatitis (CP) have not been fully elucidated. We compared regional transit times in patients with CP to those in healthy controls, and investigated whether they were associated with diabetes mellitus, exocrine dysfunction, opioid treatment or quality of life. Twenty-eight patients with CP and 28 age- and gender-matched healthy controls were included. Regional GI transit times were determined using the 3D-Transit system, which consists of an ingestible electromagnetic capsule and a detector worn in an abdominal belt for 5 days. Exocrine function was assessed using the fecal elastase-1 test, and quality of life was assessed using the European Organization for Research and Treatment of Cancer questionnaire. Transit times were analyzed for associations with diabetes mellitus, exocrine pancreatic insufficiency (EPI), opioid treatment and quality of life. Compared with healthy controls, patients with CP had prolonged transit times in the small intestine (6.6 ± 1.8 vs 4.8 ± 2.2 hours, P = .006), colon (40 ± 23 vs 28 ± 26 hours, P = .02), and total GI tract (52 ± 26 vs 36 ± 26 hours, P = .02). There was no difference in gastric emptying time (4.8 ± 5.2 vs 3.1 ± 1.3 hours, P = .9). No associations between transit times and diabetes, EPI, or opioid consumption were found (all P > .05). Quality of life and associated functional and symptom subscales were not associated with transit times, except for diarrhea (P = .03). Patients with CP have prolonged small intestinal and colonic transit times. However, these alterations do not seem to be mediated by diabetes, EPI, or opioid consumption