Response Types and Factors Associated with Response Types to Biologic Therapies in Patients with Moderate-to-Severe Plaque Psoriasis from Two Randomized Clinical Trials.

INTRODUCTION: This study aimed to understand treatment response dynamics, including factors associated with favorable response, among patients with moderate-to-severe psoriasis who received guselkumab, adalimumab, or secukinumab. METHODS: These post hoc analyses used data from the phase III clinical trials ECLIPSE and VOYAGE 1, which were conducted between September 2021 and November 2022. On the basis of absolute Psoriasis Area and Severity Index (aPASI) scores, patients were divided into short-term response types (SRT1-6, based on week 20-48 response) and long-term response types (LRT1-4, based on week 52-252 response). Response types (RTs) were based on aPASI cutoffs deemed clinically relevant by the investigators; SRT1/LRT1 were the most favorable response types. Baseline characteristics were compared across RTs, and logistic regression analyses established factors associated with SRT1/LRT1. RESULTS: Overall, 1045, 662, and 272 patients were included in the ECLIPSE short-term, VOYAGE 1 short-term, and VOYAGE 1 long-term analyses, respectively. Mean age, body mass index (BMI), baseline aPASI score, and body surface area were lower in SRT1 than SRT6. In VOYAGE 1, adalimumab treatment, high BMI, and current/former smoking status resulted in less favorable responses. In the VOYAGE 1 long-term analysis, patients in LRT4 had the highest baseline aPASI score, were older, and were more often obese compared with other LRT groups. Regression analyses showed that SRT1 (both treatments) in VOYAGE 1 and ECLIPSE, and LRT1 (guselkumab group) in the VOYAGE 1 long-term analysis, were associated with week 16 aPASI response. In VOYAGE 1, SRT1 was associated with psoriasis duration and smoking status. CONCLUSIONS: Early treatment response and baseline characteristics, including smoking, psoriasis duration, and obesity, may be associated with longer-term response to biologics. TRIAL REGISTRATION NUMBERS: ECLIPSE: NCT03090100, VOYAGE 1: NCT02207231.

Guselkumab-Treated Patients with Plaque Psoriasis Who Achieved Complete Skin Clearance for ≥ 156 Consecutive Weeks: A Post-Hoc Analysis From the VOYAGE 1 Clinical Trial.

BACKGROUND: Treatment of moderate-to-severe plaque psoriasis with biologics, such as guselkumab, has demonstrated greater efficacy over traditional non-biologic treatments. However, given patient diversity, greater understanding of the relationship between patient characteristics, positive clinical outcomes, and long-term response to biologics is crucial for optimizing treatment choices. MATERIALS AND METHODS: This post-hoc analysis of the 5-year VOYAGE 1 clinical trial compares baseline characteristics of patients maintaining a Psoriasis Area and Severity Index (PASI) score of 0 at all visits for ≥ 156 consecutive weeks (PASI = 0 group) with those that never achieve PASI = 0 (comparator group), using descriptive statistics and a multiple logistic regression model. Guselkumab plasma trough concentrations in both response groups were assessed from Weeks 4-156. RESULTS: Of patients who started guselkumab treatment at Week 0 or at Week 16 after switching from placebo, 22.7% (112/494) maintained PASI = 0 for ≥ 156 consecutive weeks. Numerical differences in baseline characteristics, including age, obesity, diabetes, PASI score, disease duration, smoking status, and psoriatic arthritis comorbidity, were identified between the PASI = 0 group and comparator group. Plasma guselkumab levels were consistently higher in the PASI = 0 group. Multiple logistic regression analysis revealed absence of diabetes, lower Dermatology Life Quality Index score at baseline, and higher Week 4 guselkumab plasma concentration as significantly (p < 0.05) associated with the PASI = 0 group. CONCLUSION: A substantial (22.7%) number of guselkumab-treated patients in the VOYAGE 1 clinical trial maintained complete skin clearance for a consecutive period of ≥ 156 weeks. Factors associated with this outcome may suggest clinical benefits of holistic treatment approaches. TRIAL REGISTRATION: NCT02207231.

Guselkumab demonstrates long-term efficacy and maintenance of treatment response post-withdrawal in systemic-treatment naïve patients and non-responders to fumaric acid esters: Results from parts II and III of a randomised, active-comparator-controlled phase IIIb trial (POLARIS).

BACKGROUND: The anti-interleukin-23 antibody guselkumab demonstrated favourable Week 24 efficacy and safety over fumaric acid esters (FAE) in systemic-treatment naïve patients with moderate-to-severe plaque psoriasis (study part I). OBJECTIVES: Part II: compare a) sustainability of treatment responses (Weeks 24-32) in guselkumab- and FAE-treated patients and b) treatment responses (Weeks 32-56) in patients treated with guselkumab, FAE, and FAE non-responders switching to guselkumab. Part III: investigate the maintenance of response through Week 100 in patients withdrawn from guselkumab at Week 56. METHODS: At Week 0, systemic-treatment naïve patients were randomised 1:1 to guselkumab (GUS) or FAE as per label. At Week 32, patients with PASI75 response (r) continued assigned treatment (GUSr-GUS; FAEr-FAE), whereas non-responders (nr) received guselkumab (FAEnr-GUS; GUSnr-GUS). Guselkumab-treated patients with Week 56 PASI90 response were withdrawn (w) and followed until loss of response or Week 100. RESULTS: At Week 32, 98.2% (54/55) of guselkumab- and 41.2% (14/34) of FAE-treated patients were PASI75 responders. At Week 56, 90.7%, 50.0% and 80.0% of GUSr-GUS, FAEr-FAE and FAEnr-GUS patients, respectively, achieved a PASI90 response; 72.2%, 28.6% and 45.0%, respectively, achieved a DLQI score 0/1. At Week 100, 44 weeks post-withdrawal, 47.2% (17/36) and 25.0% (3/12) of GUS-GUSw and FAE-GUSw patients, respectively, maintained PASI score ≤5. Overall, the adverse event and discontinuation rates were lower for guselkumab than FAE. CONCLUSIONS: In these exploratory analyses, guselkumab, as a first-line systemic treatment or second-line systemic treatment in FAE non-responders, was associated with long-term clinical efficacy up to Week 100, including a withdrawal period.

Nail psoriasis dynamics during biologic treatment and withdrawal in patients with psoriasis who may be at high risk of developing psoriatic arthritis: a post hoc analysis of the VOYAGE 2 randomized trial.

BACKGROUND: Nail psoriasis is a common, physiologically, and psychologically disruptive, and yet often under-treated manifestation of psoriasis. The objectives of this analysis were to investigate the trajectory of nail psoriasis, a risk factor for psoriatic arthritis (PsA), with guselkumab vs adalimumab treatment followed by withdrawal, and determine characteristics associated with nail response in patients treated with guselkumab. METHODS: This post hoc analysis of the phase III trial VOYAGE 2 included patients with moderate-to-severe plaque psoriasis and baseline nail involvement. Nail Psoriasis Severity Index (NAPSI) and Psoriasis Area and Severity Index (PASI) were analyzed through week 48 in patients randomized to guselkumab or adalimumab. Multiple logistic regression analyzed factors associated with NAPSI 0/1 at week 24/week 48 following guselkumab treatment. In a separate analysis, patients were stratified by prior biologic experience. RESULTS: Overall, 272 vs 132 patients receiving guselkumab vs adalimumab had nail psoriasis at baseline. Lower baseline NAPSI and week 16 PASI were associated with achieving NAPSI 0/1 at week 24 (NAPSI, odds ratio 0.685 [95% confidence interval: 0.586, 0.802]; week 16 PASI, 0.469 [0.281, 0.782]) and week 48 (NAPSI, 0.784 [0.674, 0.914]; week 16 PASI, 0.557 [0.331, 0.937]) with guselkumab. Previous biologic experience did not impact NAPSI response. Following treatment withdrawal at week 28, mean NAPSI was maintained in the guselkumab arm (week 24 1.7, week 48 1.9) and increased slightly in the adalimumab arm (week 24 1.4, week 48 2.3). Mean PASI increased across both treatment arms. CONCLUSIONS: Higher skin efficacy at week 16 was associated with better nail responses during guselkumab treatment. Nail psoriasis improvements reflected skin improvements. Following guselkumab withdrawal, nail response was maintained longer than skin response. Future studies should investigate whether such improvements in nail response reduce patients' risk of later PsA development. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02207244. Registered July 31, 2014.

The biological basis of disease recurrence in psoriasis: a historical perspective and current models.

A key challenge in psoriasis therapy is the tendency for lesions to recur in previously affected anatomical locations after treatment discontinuation following lesion resolution. Available evidence supports the concept of a localized immunological 'memory' that persists in resolved skin after complete disappearance of visible inflammation, as well as the role of a specific subpopulation of T cells characterized by the dermotropic CCR4+ phenotype and forming a local memory. Increasing knowledge of the interleukin (IL)-23/T helper 17 (Th17) cell pathway in psoriasis immunopathology is pointing away from the historical classification of psoriasis as primarily a Th1-type disease. Research undertaken from the 1990s to the mid-2000s provided evidence for the existence of a large population of CD8+ and CD4+ tissue-resident memory T cells in resolved skin, which can initiate and perpetuate immune responses of psoriasis in the absence of T-cell recruitment from the blood. Dendritic cells (DCs) are antigen-presenting cells that contribute to psoriasis pathology via the secretion of IL-23, the upstream regulator of Th17 cells, while plasmacytoid DCs are involved via IL-36 signalling and type I interferon activation. Overall, the evidence discussed in this review indicates that IL-23-driven/IL-17-producing T cells play a critical role in psoriasis pathology and recurrence, making these cytokines logical therapeutic targets. The review also explains the clinical efficacy of IL-17 and IL-23 receptor blockers in the treatment of psoriasis.

Real-world effectiveness of guselkumab in patients with psoriasis: Health-related quality of life and efficacy data from the noninterventional, prospective, German multicenter PERSIST trial.

Psoriasis is a common, chronic inflammatory skin disorder negatively impacting health-related quality of life (HRQoL). Guselkumab, targeting interleukin-23 (IL-23), is an approved biologic therapy for psoriasis. PERSIST is an ongoing prospective, noninterventional, long-term, German multicenter study evaluating the effect of guselkumab on HRQoL, and its efficacy and safety in patients with moderate-to-severe psoriasis in a real-world setting. The primary endpoint is the proportion of patients with a Dermatology Life Quality Index (DLQI) score ≤ 1 at week 28. Of 303 patients enrolled and treated with guselkumab, mean age and disease duration were 49.7 and 21.0 years, respectively, and 51.2% (n = 155) of patients had received ≥1 prior biologic therapy. Mean baseline DLQI score was 13.7, and mean symptom and sign scores in the Psoriasis Symptoms and Signs Diary (PSSD) were 51.9 and 60.8, respectively. Baseline Psoriasis Area Severity Index (PASI) and body surface area (%) scores were 16.4 and 27.5. Following 28 weeks of guselkumab treatment, the mean DLQI score decreased to 2.8, and 56.8% of patients (n = 150) achieved DLQI ≤ 1. Mean PSSD symptom and sign scores also improved, decreasing to 12.5 and 15.9, respectively. At week 28, PASI 90 response was 55.3%; significant improvement was observed in patients with psoriasis in difficult-to-treat areas. Overall, analyses demonstrated that guselkumab was effective in the real-world setting, as measured by HRQoL and skin improvements, even in patients with a high burden of disease and those who have received multiple biologic therapies. No new safety signals were observed.

IL-23 blockade with guselkumab potentially modifies psoriasis pathogenesis: rationale and study protocol of a phase 3b, randomised, double-blind, multicentre study in participants with moderate-to-severe plaque-type psoriasis (GUIDE).

BACKGROUND: Guselkumab is an interleukin (IL)-23 pathway blocker with proven efficacy in patients with moderate-to-severe plaque psoriasis. Early intervention with guselkumab may result in changes to the clinical disease course versus later intervention. METHODS AND ANALYSIS: Here we present the rationale and design of a phase 3b, randomised, double-blind, multicentre study (GUIDE), comparing treatment effects of guselkumab in patients with short (≤2 years) or longer (>2 years) duration of plaque-type psoriasis, measured from first appearance of psoriatic plaques. Participants achieving skin clearance (Psoriasis Area and Severity Index (PASI)=0) by week 20 and maintaining complete clearance at week 28 visit ('super-responders' (SRe)) will be randomised to continue approved maintenance dosing every 8 weeks (q8w) versus an investigational maintenance dosing interval of 16 weeks (q16w) until week 68. Primary endpoint: proportion of participants in the q8w vs q16w arms with absolute PASI <3 at week 68. Participants with PASI <3 at week 68 will be withdrawn from guselkumab treatment for up to 48 weeks. Participants not achieving SRe criteria (non-SRe) will remain in the study with q8w guselkumab dosing through week 68. Additional to serum samples obtained from all patients, skin biopsies and whole-blood samples will be taken from SRe and non-SRe participants at various time points in optional substudies. Analyses include: genetics; immunophenotyping (fluorescence-activated cell sorting); gene and protein expression profiling; immunohistology. By merging clinical endpoints with mechanistic findings, this study aims to elucidate how IL-23 blockade with guselkumab can modify the disease course by altering molecular and cellular drivers that cause relapse after treatment withdrawal, particularly among SRe. ETHICS AND DISSEMINATION: Approval obtained from ethics committee Medical Council Hamburg, Germany (PVN5925). GUIDE is compliant with the Declaration of Helsinki. TRIAL REGISTRATION NUMBER: Registered at ClinicalTrials.gov (NCT03818035). All primary endpoint results (prespecified analyses) will be submitted to peer-reviewed, international journals within 18 months after primary completion date.

Timed daily exercise remodels circadian rhythms in mice.

Regular exercise is important for physical and mental health. An underexplored and intriguing property of exercise is its actions on the body's 24 h or circadian rhythms. Molecular clock cells in the brain's suprachiasmatic nuclei (SCN) use electrical and chemical signals to orchestrate their activity and convey time of day information to the rest of the brain and body. To date, the long-lasting effects of regular physical exercise on SCN clock cell coordination and communication remain unresolved. Utilizing mouse models in which SCN intercellular neuropeptide signaling is impaired as well as those with intact SCN neurochemical signaling, we examined how daily scheduled voluntary exercise (SVE) influenced behavioral rhythms and SCN molecular and neuronal activities. We show that in mice with disrupted neuropeptide signaling, SVE promotes SCN clock cell synchrony and robust 24 h rhythms in behavior. Interestingly, in both intact and neuropeptide signaling deficient animals, SVE reduces SCN neural activity and alters GABAergic signaling. These findings illustrate the potential utility of regular exercise as a long-lasting and effective non-invasive intervention in the elderly or mentally ill where circadian rhythms can be blunted and poorly aligned to the external world.

A circadian clock in the sinus node mediates day-night rhythms in Hcn4 and heart rate.

BACKGROUND: Heart rate follows a diurnal variation, and slow heart rhythms occur primarily at night. OBJECTIVE: The lower heart rate during sleep is assumed to be neural in origin, but here we tested whether a day-night difference in intrinsic pacemaking is involved. METHODS: In vivo and in vitro electrocardiographic recordings, vagotomy, transgenics, quantitative polymerase chain reaction, Western blotting, immunohistochemistry, patch clamp, reporter bioluminescence recordings, and chromatin immunoprecipitation were used. RESULTS: The day-night difference in the average heart rate of mice was independent of fluctuations in average locomotor activity and persisted under pharmacological, surgical, and transgenic interruption of autonomic input to the heart. Spontaneous beating rate of isolated (ie, denervated) sinus node (SN) preparations exhibited a day-night rhythm concomitant with rhythmic messenger RNA expression of ion channels including hyperpolarization-activated cyclic nucleotide-gated potassium channel 4 (HCN4). In vitro studies demonstrated 24-hour rhythms in the human HCN4 promoter and the corresponding funny current. The day-night heart rate difference in mice was abolished by HCN block, both in vivo and in the isolated SN. Rhythmic expression of canonical circadian clock transcription factors, for example, Brain and muscle ARNT-Like 1 (BMAL1) and Cryptochrome (CRY) was identified in the SN and disruption of the local clock (by cardiomyocyte-specific knockout of Bmal1) abolished the day-night difference in Hcn4 and intrinsic heart rate. Chromatin immunoprecipitation revealed specific BMAL1 binding sites on Hcn4, linking the local clock with intrinsic rate control. CONCLUSION: The circadian variation in heart rate involves SN local clock-dependent Hcn4 rhythmicity. Data reveal a novel regulator of heart rate and mechanistic insight into bradycardia during sleep.

Evolution of HCV patient characteristics and DAA regimens in the German Hepatitis C Registry (DHC-R) in 2014 and 2015.

BACKGROUND: The urgent need in HCV-infected patients with liver disease mandated the rapid implementation of IFN-free DAA combination therapies following their regulatory approval in 2014 and 2015 without full knowledge of the optimal combinations and regimens. Investigating the evolution of the DAA utilization patterns and treatment outcomes could provide learnings for future situations. METHODS: This was an analysis of a prospective observational database from the German Hepatitis C Registry (DHC-R) covering a period from May 2014 to September 2015. Adult patients had evidence of chronic HCV GT1 or GT4 infection and were treated with an IFN-free combination regimen of simeprevir (SMV) + sofosbuvir (SOF) or other IFN-free regimens: daclatasvir + sofosbuvir (DCV + SOF), ledipasvir/sofosbuvir (SOF/LDV), paritaprevir/r + ombitasvir ± dasabuvir (PrOD), with or without ribavirine (R). RESULTS: A total of 5496 subjects were followed during the period. During this period, clinical recommendations and treatment patterns evolved rapidly in response to new evidence from clinical trials and clinical routine and regulatory approval of additional regimens. High SVR12 rates were seen in this cohort, even in hard-to-treat patient subgroups. In the multivariate analysis, gender, age, advanced cirrhosis, and intensified treatment for cirrhotics were associated with treatment outcome. CONCLUSION: Despite limited knowledge of the optimal utilization of the newly approved DAA combinations and treatment durations as well as their comparative efficacy and safety profiles, high SVR rates were achieved regardless of the DAA combination. These outcomes were facilitated by the rapid adaptation of clinical recommendations. Future situations with high unmet medical need may follow a similar approach.

An outlook on self-assessment of homework assignments in higher mathematics education.

BACKGROUND: We discuss first experiences with a new variant of self-assessment in higher mathematics education. In our setting, the students of the course have to mark a part of their homework assignments themselves and they receive the corresponding credit without that any later changes are carried out by the teacher. In this way, we seek to correct the imbalance between student-centered learning arrangements and assessment concepts that keep the privilege to grade (or mark) completely with the teacher. RESULTS: We present results in the form of student feedback from a course on functional analysis for third- and fourth-year students. Moreover, we analyze marking results from two courses on real analysis. Here, we compare tasks marked by the teacher and tasks marked by the students. CONCLUSIONS: Our experiments indicate that students can benefit from self-assessment tasks. The success depends, however, on many different factors. Promising for self-assessment seem to be small learning groups and tasks in which a priori weaker students can catch up with stronger students by increasing their practising time.

Delayed Cryptochrome Degradation Asymmetrically Alters the Daily Rhythm in Suprachiasmatic Clock Neuron Excitability.

Suprachiasmatic nuclei (SCN) neurons contain an intracellular molecular circadian clock and the Cryptochromes (CRY1/2), key transcriptional repressors of this molecular apparatus, are subject to post-translational modification through ubiquitination and targeting for proteosomal degradation by the ubiquitin E3 ligase complex. Loss-of-function point mutations in a component of this ligase complex, Fbxl3, delay CRY1/2 degradation, reduce circadian rhythm strength, and lengthen the circadian period by ∼2.5 h. The molecular clock drives circadian changes in the membrane properties of SCN neurons, but it is unclear how alterations in CRY1/2 stability affect SCN neurophysiology. Here we use male and female Afterhours mice which carry the circadian period lengthening loss-of-function Fbxl3Afh mutation and perform patch-clamp recordings from SCN brain slices across the projected day/night cycle. We find that the daily rhythm in membrane excitability in the ventral SCN (vSCN) was enhanced in amplitude and delayed in timing in Fbxl3Afh/Afh mice. At night, vSCN cells from Fbxl3Afh/Afh mice were more hyperpolarized, receiving more GABAergic input than their Fbxl3+/+ counterparts. Unexpectedly, the progression to daytime hyperexcited states was slowed by Afh mutation, whereas the decline to hypoexcited states was accelerated. In long-term bioluminescence recordings, GABAA receptor blockade desynchronized the Fbxl3+/+ but not the Fbxl3Afh/Afh vSCN neuronal network. Further, a neurochemical mimic of the light input pathway evoked larger shifts in molecular clock rhythms in Fbxl3Afh/Afh compared with Fbxl3+/+ SCN slices. These results reveal unanticipated consequences of delaying CRY degradation, indicating that the Afh mutation prolongs nighttime hyperpolarized states of vSCN cells through increased GABAergic synaptic transmission.SIGNIFICANCE STATEMENT The intracellular molecular clock drives changes in SCN neuronal excitability, but it is unclear how mutations affecting post-translational modification of molecular clock proteins influence the temporal expression of SCN neuronal state or intercellular communication within the SCN network. Here we show for the first time, that a mutation that prolongs the stability of key components of the intracellular clock, the cryptochrome proteins, unexpectedly increases in the expression of hypoexcited neuronal state in the ventral SCN at night and enhances hyperpolarization of ventral SCN neurons at this time. This is accompanied by increased GABAergic signaling and by enhanced responsiveness to a neurochemical mimic of the light input pathway to the SCN. Therefore, post-translational modification shapes SCN neuronal state and network properties.

Intrinsic and extrinsic cues regulate the daily profile of mouse lateral habenula neuronal activity.

The epithalamic lateral habenula (LHb) is implicated as part of the mammalian brain's circadian system. Anatomical evidence suggests that the LHb receives extrinsic circadian timing cues from retinal ganglion cells and the master clock in the suprachiasmatic nuclei (SCN). Intriguingly, some LHb neurones contain the molecular circadian clock, but it is unclear if and how intrinsic and extrinsic circadian processes influence neuronal activity in the mouse LHb. Here, using an in vitro brain slice preparation isolating the LHb from the SCN, we show through whole-cell patch-clamp recordings that LHb neurones exhibit heterogeneity in their resting state, but the majority spontaneously fire action potentials (APs). Discharge rate of APs varied from low firing in the early day to higher firing later in the day and was absent in LHb brain slices prepared from Cry1(-/-)Cry2(-/-) mice that lack a functional molecular clock. Low amplitude circadian oscillations in the molecular circadian clock were also monitored in LHb brain slices, but were absent in Cry1(-/-)Cry2(-/-) LHb brain tissue. A putative neurochemical output signal of the SCN, prokineticin 2 (PK2), inhibited some LHb neurones by elevating the frequency of GABA release in the LHb. Using multi-electrode recordings in vivo, we found that LHb neurones sluggishly respond to retinal illumination, suggesting that they receive such information through polysynaptic processes. In summary, our results show for the first time that intrinsic circadian signals are important for regulating LHb neuronal state, while the SCN-derived signal PK2 is less influential. Moreover, we demonstrate that mouse LHb neurones have access to and can respond to visual input, but such signals are unlikely to be directly communicated to the LHb. Broadly, these findings raise the possibility that intrinsic circadian signals are likely to be influential in shaping LHb contributions to cognition and emotionality.

Levetiracetam but not valproate inhibits function of CD8+ T lymphocytes.

PURPOSE: To further elucidate possible immune-modulatory effects of valproate (VPA) or levetiracetam (LEV), we investigated their influence on apoptosis and cytotoxic function of CD8+ T lymphocytes in humans. METHODS: In 15 healthy subjects (9 female (60%), 35.7±12.1 years), apoptosis and cytotoxic function of CD8+ T lymphocytes were measured using flow cytometry following in vitro exposure to LEV (5 mg/L and 50 mg/L) and VPA (10mg/L and 100 mg/L). Apoptosis rates were determined after incubation with LEV or VPA for 1 h or 24 h. Cytotoxic function was assessed following 2h stimulation with mixed virus peptides, using perforin release, CD107a/b expression and proliferation. The presence of synaptic vesicle protein 2A (SV2A) was investigated in human CD8+ T lymphocytes by flow cytometry analysis, Western blot and real time polymerase chain reaction (rtPCR). RESULTS: High concentration of LEV decreased perforin release of CD8+ T lymphocytes (LEV 50 mg/L vs. CEF only: 21.4% (interquartile range (IQR) 16.5-35.9%) vs. 16.6% (IQR 12-24.9%), p=0.002). LEV had no influence on apoptosis and proliferation (p>0.05). VPA (100 mg/L) slowed apoptosis of CD8() T lymphocytes after 24h (VPA 100mg/L vs. control: 7.3% (IQR 5.4-9.5%) vs. 11.3% (IQR 8.2-15.1%), p<0.001), but had no effects on perforin release (p>0.05). SV2A protein was detected in CD8+ T lymphocytes. CONCLUSION: LEV decreased degranulation of CD8+ T lymphocytes which may contribute to the increased incidence of upper respiratory tract infections in LEV treated patients. Inhibition of SV2A may be responsible for this effect.

Suppressed cellular oscillations in after-hours mutant mice are associated with enhanced circadian phase-resetting.

Within the core molecular clock, protein phosphorylation and degradation play a vital role in determining circadian period. The 'after-hours' (Afh) mutation in mouse slows the degradation of the core clock protein Cryptochrome, lengthening the period of the molecular clock in the suprachiasmatic nuclei (SCN) and behavioural wheel-running rhythms. However, we do not yet know how the Afh mutation affects other aspects of physiology or the activity of circadian oscillators in other brain regions. Here we report that daily rhythms of metabolism and ingestive behaviours are altered in these animals, as are PERIOD2::LUCIFERASE (PER2::LUC) rhythms in mediobasal hypothalamic nuclei, which influence these behaviours. Overall there is a trend towards period lengthening and a decrease in amplitude of PER2::LUC rhythms throughout the brain. Imaging of single cells from the arcuate and dorsomedial hypothalamic nuclei revealed this reduction in tissue oscillator amplitude to be due to a decrease in the amplitude, rather than a desynchrony, of single cells. Consistent with existing models of oscillator function, this cellular phenotype was associated with a greater susceptibility to phase-shifting stimuli in vivo and in vitro, with light evoking high-amplitude Type 0 resetting in Afh mutant mice. Together, these findings reveal unexpected consequences of the Afh mutation on the amplitude and synchrony of individual cellular oscillators in the SCN.

Electrical stimulation-induced seizures in rats: a "dose-response" study on resultant neurodegeneration.

Perforant pathway stimulation (PPS) is used to study temporal lobe epilepsy in rodents. High-frequency PPS induces acute seizures, which can lead to neuron death and spontaneous epilepsy. However, the minimum duration of PPS that induces neurodegeneration in naive rodents is unknown. Freely moving Sprague-Dawley rats received one episode of continuous, bilateral PPS (range 1-180 min). Simultaneous recording from the hippocampal granule cell layer confirmed the presence of epileptiform activity and showed precisely when seizure activity was terminated by anesthesia. Fluoro-Jade B staining, 1-7 days after PPS, determined neuronal degeneration. Thirty-five minutes of continuous PPS produced no apparent neuron death anywhere in the brain. The minimum duration that caused neurodegeneration, which was confined to the dentate hilus, was 40 min. These data indicate that, in freely moving naive rats: (1) 40 min of PPS-induced seizure activity is the threshold for brain cell death, and (2) dentate hilar neurons are the most vulnerable to PPS. Further studies are warranted to determine the threshold of epileptogenic neurodegeneration.

RNA editing of Kv1.1 channels may account for reduced ictogenic potential of 4-aminopyridine in chronic epileptic rats.

In rat brain slices, the Kv channel blocker 4-aminopyridine (4-AP) induces seizure-like events. This effect is absent in slices from chronic epileptic rats generated using the kainic acid model. The reason for this phenomenon remained elusive as an altered expression level of Kv channels was ruled out as a mechanism. We recently described that the Ile400Val RNA editing of Kv1.1 generates 4-AP-insensitive Kv1 channels (Kv1.1(I400V)). We therefore hypothesized that altered RNA editing levels account for the reduced ictogenic potency of 4-AP in chronic epileptic rats. We found fourfold increased RNA editing ratios in the entorhinal cortex of chronic epileptic animals compared to healthy control animals. Electrophysiologic recordings in Xenopus oocytes revealed that the observed increased Kv1.1(I400V) editing level can in fact lead to significant loss of 4-AP sensitivity. Our data suggest that altered Kv1.1(I400V) RNA editing contributes to the reduced ictogenic potential of 4-AP in chronic epileptic rats.

Effects of divalent cations and spermine on the K+ channel TASK-3 and on the outward current in thalamic neurons.

The potassium channels TASK-1 and TASK-3 show high sequence homology but differ in their sensitivity to extracellular divalent cations. Heterologous expression in HEK293 cells showed that the single-channel conductance of TASK-3 increased approximately four-fold after removal of external divalent cations, whereas the conductance of TASK-1 was unaffected. Replacing the glutamate at position 70 of TASK-3 by a lysine or arginine residue abolished the sensitivity to divalent cations. The reverse mutation in TASK-1 (K70E) induced sensitivity to divalent cations. The organic polycations spermine and ruthenium red modulated the conductance of TASK-3 in a similar way as Ca2+ or Mg2+. Our data suggest that these effects were mediated by shielding of the negative charges in the extracellular loops of TASK-3. Whole-cell currents carried by TASK-3 channels were inhibited by spermine and ruthenium red even in the presence of external divalent cations. These data suggest that, in addition to their effect on single-channel conductance, spermine and ruthenium red decreased the open probability of TASK-3 channels, probably by binding to residue E70. The standing outward current in thalamocortical relay neurons, which is largely carried by TASK channels, was also inhibited by divalent cations and spermine. Using the differential sensitivity of TASK-1 and TASK-3 to divalent cations and spermine we found that about 20% of the standing outward current in thalamocortical relay neurons flows through TASK-3 channels. We conclude from our results that inhibition of TASK-3 channels may contribute to the neuromodulatory effect of spermine released from neurons during repetitive activity or during hypoxia.