Az aktin citoszkeleton szabályozásának molekuláris aspektusai = Molecular Aspects of the Actin Cytoskeleton

Munkánk során számos - az aktin és az aktin citoszkeleton működésében fontos szerepet játszó - fehérje molekuláris tulajdonságait és kölcsönhatásait leírtuk. Folytattuk az aktin és miozin fehérjék kölcsönhatásának feltérképezését. Nemzetközi kooperációk keretei között gyors kinetikai módszereket alkalmazva jellemeztünk rovar (Drosophila) izomból származó miozint. Fluoreszcencia spektroszkópiai és kalorimetriai módszerekkel tanulmányoztuk az aktin kölcsönhatását toxikus peptidekkel (falloidin és jasplakinolid). A miozinok működésében meghatározó szerepet játszó nukleotidok, azokon belül is az ADP szerepét írtuk le részletesen egy összefoglaló cikkben. Vizsgáltuk a nem izom eredetű miozinok közül a patkányból származó miozin IX kinetikai tulajdonságait. Egy másik vizsgálatsorozatban a különböző emlős állatokból származó lassú és gyors miozin izoformák tulajdonságait írtuk le kinetikai módszerek segítségével. Ugyancsak nemzetközi együttműködés keretein belül tanulmányoztuk az aktinnak a forminokkal, a forminokon belül is az ún. Diaphanous Related forminokkal való kölcsönhatását. Megállapítottuk azt is, hogy az emlős (egér) sejtekből származó formin fragmentumok megváltoztatják az aktin filamentumok dinamikai tulajdonságait, konformációját. | We characterised a number of actin-binding proteins during the project. We described the dynamic aspects of the interaction between actin and myosin from rabbit skeletal muscle by using spectroscopic methods. Within the framework of international collaboration the properties of Drosophila flight muscle myosin was also investigated by rapid kinetic methods. We described the effect of toxic peptides (phalloidin and jasplakinolide) on the actin filaments by spectroscopic and calorimetric methods. By using rapid kinetic methods we studied the behaviour of a non-muscle myosin, rat myosin IX. In a separate study we described the differences between mysoin isoforms from various mammalian species. In another international collaboration we studied the interaction between actin and mammalian formins. We also showed by using specrtroscopic methods that these formin fragments change the dynamic and conformational properties of actin filaments

Effects of the Pentapeptide P33 on Memory and Synaptic Plasticity in APP/PS1 Transgenic Mice: A Novel Mechanism Presenting the Protein Fe65 as a Target

Regulated intramembrane proteolysis (RIP) of the amyloid precursor protein (APP) leads to the formation of fragments, among which the intracellular domain of APP (AICD) was also identified to be a causative of early pathological events. AICD-counteracting proteins, such as Fe65, may serve as alternative therapeutic targets of Alzheimer's disease (AD). The detection of elevated levels of Fe65 in the brains of both human patients and APP transgenic mice may further strengthen the hypothesis that influencing the interaction between Fe65 and APP may have a beneficial effect on the course of AD. Based on a PXP motif, proven to bind to the WW domain of Fe65, a new pentapeptide was designed and tested. The impedimental effect of P33 on the production of beta amyloid (A beta) (soluble fraction and aggregated plaques) and on the typical features of the AD pathology (decreased dendritic spine density, synaptic markers, elevated inflammatory reactions) was also demonstrated. Significant enhancements of both learning ability and memory function were observed in a Morris water maze paradigm. The results led us to formulate the theory that P33 acts by altering the conformation of Fe65 via binding to its WW domain, consequently hindering any interactions between Fe65 and key members involved in APP processing

Recurrent acute pancreatitis prevention by the elimination of alcohol and cigarette smoking (REAPPEAR): protocol of a randomised controlled trial and a cohort study

Background/objectives Acute recurrent pancreatitis (ARP) due to alcohol and/or tobacco abuse is a preventable disease which lowers quality of life and can lead to chronic pancreatitis. The REAPPEAR study aims to investigate whether a combined patient education and cessation programme for smoking and alcohol prevents ARP. Methods and analysis The REAPPEAR study consists of an international multicentre randomised controlled trial (REAPPEAR-T) testing the efficacy of a cessation programme on alcohol and smoking and a prospective cohort study (REAPPEAR-C) assessing the effects of change in alcohol consumption and smoking (irrespective of intervention). Daily smoker patients hospitalised with alcohol-induced acute pancreatitis (AP) will be enrolled. All patients will receive a standard intervention priorly to encourage alcohol and smoking cessation. Participants will be subjected to laboratory testing, measurement of blood pressure and body mass index and will provide blood, hair and urine samples for later biomarker analysis. Addiction, motivation to change, socioeconomic status and quality of life will be evaluated with questionnaires. In the trial, patients will be randomised either to the cessation programme with 3-monthly visits or to the control group with annual visits. Participants of the cessation programme will receive a brief intervention at every visit with direct feedback on their alcohol consumption based on laboratory results. The primary endpoint will be the composite of 2-year all-cause recurrence rate of AP and/or 2-year all-cause mortality. The cost-effectiveness of the cessation programme will be evaluated. An estimated 182 participants will be enrolled per group to the REAPPEAR-T with further enrolment to the cohort

Red Blood Cell Transfusion in European Neonatal Intensive Care Units, 2022 to 2023

International audienceIMPORTANCE Red blood cell (RBC) transfusions are frequently administered to preterm infants born before 32 weeks of gestation in the neonatal intensive care unit (NICU). Two randomized clinical trials (Effects of Transfusion Thresholds on Neurocognitive Outcomes of Extremely Low-Birth-Weight Infants [ETTNO] and Transfusion of Prematures [TOP]) found that liberal RBC transfusion thresholds are nonsuperior to restrictive thresholds, but the extent to which these results have been integrated into clinical practice since publication in 2020 is unknown. OBJECTIVE To describe neonatal RBC transfusion practice in Europe. DESIGN, SETTING, AND PARTICIPANTS This international prospective observational cohort study collected data between September 1, 2022, and August 31, 2023, with a 6-week observation period per center, from 64 NICUs in 22 European countries. Participants included 1143 preterm infants born before 32 weeks of gestation. EXPOSURE Admission to the NICU. MAIN OUTCOMES AND MEASURES Study outcome measures included RBC transfusion prevalence rates, cumulative incidence, indications, pretransfusion hemoglobin (Hb) levels, volumes, and transfusion rates, Hb increment, and adverse effects of RBC transfusion. RESULTS A total of 1143 preterm infants were included (641 male [56.1%]; median gestational age at birth, 28 weeks plus 2 days [IQR, 26 weeks plus 2 days to 30 weeks plus 2 days]; median birth weight, 1030 [IQR, 780-1350] g), of whom 396 received 1 or more RBC transfusions, totaling 903 transfusions. Overall RBC transfusion prevalence rate during postnatal days 1 to 28 was 3.4 transfusion days per 100 admission days, with considerable variation across countries, only partly explained by patient mix. By day 28, 36.5% (95% CI, 31.6%-41.5%) of infants had received at least 1 transfusion. Most transfusions were given based on a defined Hb threshold (748 [82.8%]). Hemoglobin levels before transfusions indicated for threshold were below the restrictive thresholds set by ETTNO in 324 of 729 transfusions (44.4%) and TOP in 265 of 729 (36.4%). Conversely, they were between restrictive and liberal thresholds in 352 (48.3%) and 409 (56.1%) transfusions, respectively, and above liberal thresholds in 53 (7.3%) and 55 (7.5%) transfusions, respectively. Most transfusions given based on threshold had volumes of 15 mL/kg (470 of 738 [63.7%]) and were administered over 3 hours (400 of 738 [54.2%]), but there was substantial variation in dose and duration. CONCLUSIONS AND RELEVANCE In this cohort study of very preterm infants, most transfusions indicated for threshold were given for pretransfusion Hb levels above restrictive transfusion thresholds evaluated in recent trials. These results underline the need to optimize practices and for implementation research to support uptake of evidence