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Eine barrierefreie Teilnahme am alltäglichen Leben stellt für Menschen mit aktiver Epilepsie häufig eine Herausforderung dar. Epileptische Anfälle können in Kindergarten, Schule und am Arbeitsplatz sowie im häuslichen Umfeld Unsicherheit und Überforderung hervorrufen. Individuell erstellte Pläne für Betreuende, Angehörige, Aufsichtspersonen und den Rettungsdienst sollen im Falle eines akuten Anfalls geeignete Handlungsanweisungen geben. Bisher gibt es hierfür im deutschsprachigen Raum keine standardisierten Vorlagen. Mit den Handlungsplänen bei epileptischen Anfällen für Laien (HEAL) bzw. Therapeuten (HEAT) werden hier 2 Formulare vorgestellt, die zum einen eine standardisierte Grundlage bieten und andererseits leicht auf den individuellen Bedarf angepasst werden können.
Eine barrierefreie Teilnahme am alltäglichen Leben stellt für Menschen mit aktiver Epilepsie häufig eine Herausforderung dar. Epileptische Anfälle können in Kindergarten, Schule und am Arbeitsplatz sowie im häuslichen Umfeld Unsicherheit und Überforderung hervorrufen. Individuell erstellte Pläne für Betreuende, Angehörige, Aufsichtspersonen und den Rettungsdienst sollen im Falle eines akuten Anfalls geeignete Handlungsanweisungen geben. Bisher gibt es hierfür im deutschsprachigen Raum keine standardisierten Vorlagen. Mit den Handlungsplänen bei epileptischen Anfällen für Laien (HEAL) bzw. Therapeuten (HEAT) werden hier 2 Formulare vorgestellt, die zum einen eine standardisierte Grundlage bieten und andererseits leicht auf den individuellen Bedarf angepasst werden können.
Akzidentielle Injektion eines unbekannten Notfallantidots zur Acetylcholinesteraseaktivierung
(2021)
Albumin, the most abundant plasma protein, not only controls osmotic blood pressure, but also serves as a carrier for various small molecules, including pharmaceuticals. Its impact on pharmacological properties of many drugs has been extensively studied over decades. Here, we focus on its interaction with the following mobilizing agents: Granulocyte-colony stimulating factor (G-CSF) and AMD3100, where such analyses are lacking. These compounds are widely used for hematopoietic stem cell mobilization of healthy donors or patients. Using albumin-deficient (Alb−/−) mice, we studied the contribution of albumin to mobilization outcomes. Mobilization with the bicyclam CXCR4 antagonist AMD3100 was attenuated in Alb−/− mice compared to wild-type littermates. By contrast, mobilization with recombinant human G-CSF (rhG-CSF), administered twice daily over a five-day course, was significantly increased in Alb−/− mice. In terms of a mechanism, we show that rhG-CSF bioavailability in the bone marrow is significantly improved in Alb−/− mice, compared to wild-type (WT) littermates, where rhG-CSF levels dramatically drop within a few hours of the injection. These observations likely explain the favorable mobilization outcomes with split-dose versus single-dose administration of rhG-CSF to healthy donors.
The spectrum of alcoholic liver disease (ALD) is broad and includes alcoholic fatty liver, alcoholic steatohepatitis, alcoholic hepatitis, alcoholic fibrosis, alcoholic cirrhosis, and alcoholic hepatocellular carcinoma, best explained as a five-hit sequelae of injurious steps. ALD is not primarily the result of malnutrition as assumed for many decades but due to the ingested alcohol and its metabolic consequences although malnutrition may marginally contribute to disease aggravation. Ethanol is metabolized in the liver to the heavily reactive acetaldehyde via the alcohol dehydrogenase (ADH) and the cytochrome P450 isoform 2E1 of the microsomal ethanol-oxidizing system (MEOS). The resulting disturbances modify not only the liver parenchymal cells but also non-parenchymal cells such as Kupffer cells (KCs), hepatic stellate cells (HSCs), and liver sinusoidal endothelial cells (LSECs). These are activated by acetaldehyde, reactive oxygen species (ROS), and endotoxins, which are produced from bacteria in the gut and reach the liver due to gut leakage. A variety of intrahepatic signaling pathways and innate or acquired immune reactions are under discussion contributing to the pathogenesis of ALD via the five injurious hits responsible for disease aggravation. As some of the mechanistic steps are based on studies with in vitro cell systems or animal models, respective proposals for humans may be considered as tentative. However, sufficient evidence is provided for clinical risk factors that include the amount of alcohol used daily for more than a decade, gender differences with higher susceptibility of women, genetic predisposition, and preexisting liver disease. In essence, efforts within the last years were devoted to shed more light in the pathogenesis of ALD, much has been achieved but issues remain to what extent results obtained from experimental studies can be transferred to humans.
Few sequence alignment methods have been designed specifically for integral membrane proteins, even though these important proteins have distinct evolutionary and structural properties that might affect their alignments. Existing approaches typically consider membrane-related information either by using membrane-specific substitution matrices or by assigning distinct penalties for gap creation in transmembrane and non-transmembrane regions. Here, we ask whether favoring matching of predicted transmembrane segments within a standard dynamic programming algorithm can improve the accuracy of pairwise membrane protein sequence alignments. We tested various strategies using a specifically designed program called AlignMe. An updated set of homologous membrane protein structures, called HOMEP2, was used as a reference for optimizing the gap penalties. The best of the membrane-protein optimized approaches were then tested on an independent reference set of membrane protein sequence alignments from the BAliBASE collection. When secondary structure (S) matching was combined with evolutionary information (using a position-specific substitution matrix (P)), in an approach we called AlignMePS, the resultant pairwise alignments were typically among the most accurate over a broad range of sequence similarities when compared to available methods. Matching transmembrane predictions (T), in addition to evolutionary information, and secondary-structure predictions, in an approach called AlignMePST, generally reduces the accuracy of the alignments of closely-related proteins in the BAliBASE set relative to AlignMePS, but may be useful in cases of extremely distantly related proteins for which sequence information is less informative. The open source AlignMe code is available at https://sourceforge.net/projects/alignme/, and at http://www.forrestlab.org, along with an online server and the HOMEP2 data set.
Background and Aims: Intoxications by aliphatic halogenated hydrocarbons (AHH), used as effective solvents, are rare and may cause life-threatening liver injury. Patients with acute intoxications by AHH received an innovative treatment.
Methods: Analyzed were data of 60 patients intoxicated by AHH, such as dichloromethane (n = 3), chloroform (n = 2), carbon tetrachloride (n = 12), 1,2-dichloroethane (n = 18), 1,1,2-trichloroethane (n = 2), trichloroethylene (n = 2), tetrachloroethylene (n = 13) or mixed AHH chemicals (n = 8), who received a new treatment consisting of CO2-induced hyperventilation to accelerate toxin removal via the lungs.
Results: Added to the inspiration air at a flow rate of 2–3 Liter min−1, CO2 increased the respiratory volume up to 25–30 Liter min−1, ensuring forced AHH exhalation. This CO2-induced hyperventilation therapy was commonly well tolerated by the 60 patients and lasted for 106.0±10.5 hours. In most cases, initially increased liver test results of aminotransferases normalized quickly under the therapy, and liver histology obtained at completion of the therapy revealed, in the majority of patients, normal findings or fatty changes, and rarely severe single cell necrosis but no confluent liver cell necrosis. Despite therapy, clinical outcome was unfavorable for 4/60 patients (6.7%) of the study cohort, due to single or combined risk factors. These included late initiation of the CO2-induced hyperventilation therapy, intentional intoxication, uptake of high amounts of AHH, concomitant ingestion of overdosed drugs, consumption of high amounts of alcohol, and history of alcohol abuse.
Conclusions: For intoxications by AHH, effective therapy approaches including forced hyperventilation to increase toxin removal via the lungs are available and require prompt initiation.
Background: Patients with acute coronary syndrome (ACS) and concomitant noncoronary atherosclerosis have a high risk of major adverse cardiovascular events (MACEs) and death. The impact of lipid lowering by proprotein convertase subtilisin–kexin type 9 inhibition in such patients is undetermined.
Objectives: This pre-specified analysis from ODYSSEY OUTCOMES (Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab) determined whether polyvascular disease influenced risks of MACEs and death and their modification by alirocumab in patients with recent ACS and dyslipidemia despite intensive statin therapy.
Methods: Patients were randomized to alirocumab or placebo 1 to 12 months after ACS. The primary MACEs endpoint was the composite of coronary heart disease death, nonfatal myocardial infarction, fatal or nonfatal ischemic stroke, or unstable angina requiring hospitalization. All-cause death was a secondary endpoint.
Results: Median follow-up was 2.8 years. Of 18,924 patients, 17,370 had monovascular (coronary) disease, 1,405 had polyvascular disease in 2 beds (coronary and peripheral artery or cerebrovascular), and 149 had polyvascular disease in 3 beds (coronary, peripheral artery, cerebrovascular). With placebo, the incidence of MACEs by respective vascular categories was 10.0%, 22.2%, and 39.7%. With alirocumab, the corresponding absolute risk reduction was 1.4% (95% confidence interval [CI]: 0.6% to 2.3%), 1.9% (95% CI: −2.4% to 6.2%), and 13.0% (95% CI: −2.0% to 28.0%). With placebo, the incidence of death by respective vascular categories was 3.5%, 10.0%, and 21.8%; the absolute risk reduction with alirocumab was 0.4% (95% CI: −0.1% to 1.0%), 1.3% (95% CI: −1.8% to 4.3%), and 16.2% (95% CI: 5.5% to 26.8%).
Conclusions: In patients with recent ACS and dyslipidemia despite intensive statin therapy, polyvascular disease is associated with high risks of MACEs and death. The large absolute reductions in those risks with alirocumab are a potential benefit for these patients. (Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab [ODYSSEY OUTCOMES]: NCT01663402)
Alirocumab reduces total nonfatal cardiovascular and fatal events: The ODYSSEY OUTCOMES trial
(2018)
Background: The ODYSSEY OUTCOMES (Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab) trial compared alirocumab with placebo, added to high-intensity or maximum-tolerated statin treatment, after acute coronary syndrome (ACS) in 18,924 patients. Alirocumab reduced the first occurrence of the primary composite endpoint and was associated with fewer all-cause deaths.
Objectives: This pre-specified analysis determined the extent to which alirocumab reduced total (first and subsequent) nonfatal cardiovascular events and all-cause deaths in ODYSSEY OUTCOMES.
Methods: Hazard functions for total nonfatal cardiovascular events (myocardial infarction, stroke, ischemia-driven coronary revascularization, and hospitalization for unstable angina or heart failure) and death were jointly estimated, linked by a shared frailty accounting for patient risk heterogeneity and correlated within-patient nonfatal events. An association parameter also quantified the strength of the linkage between risk of nonfatal events and death. The model provides accurate relative estimates of nonfatal event risk if nonfatal events are associated with increased risk for death.
Results: With 3,064 first and 5,425 total events, 190 fewer first and 385 fewer total nonfatal cardiovascular events or deaths were observed with alirocumab compared with placebo. Alirocumab reduced total nonfatal cardiovascular events (hazard ratio: 0.87; 95% confidence interval: 0.82 to 0.93) and death (hazard ratio: 0.83; 95% confidence interval: 0.71 to 0.97) in the presence of a strong association between nonfatal and fatal event risk.
Conclusions: In patients with ACS, the total number of nonfatal cardiovascular events and deaths prevented with alirocumab was twice the number of first events prevented. Consequently, total event reduction is a more comprehensive metric to capture the totality of alirocumab clinical efficacy after ACS.
The aim of this clinical trial was to evaluate the impact of all-trans retinoic acid (ATRA) in combination with chemotherapy and to assess the NPM1 status as biomarker for ATRA therapy in younger adult patients (18-60 years) with acute myeloid leukemia (AML). Patients were randomized for intensive chemotherapy with or without open-label ATRA (45 mg/m2, days 6-8; 15 mg/m2, days 9-21). Two cycles of induction therapy were followed by risk-adapted consolidation with high-dose cytarabine or allogeneic hematopoietic cell transplantation. Due to the open label character of the study, analysis was performed on an intention-to-treat (ITT) and a per-protocol (PP) basis. One thousand one hundred patients were randomized (556, STANDARD; 544, ATRA) with 38 patients treated vice versa. Median follow-up for survival was 5.2 years. ITT analyses revealed no difference between ATRA and STANDARD for the total cohort and for the subset of NPM1-mutated AML with respect to event-free (EFS; p = 0.93, p = 0.17) and overall survival (OS; p = 0.24 and p = 0.32, respectively). Pre-specified PP analyses revealed better EFS in NPM1-mutated AML (p = 0.05) and better OS in the total cohort (p = 0.03). Explorative subgroup analyses on an ITT basis revealed better OS (p = 0.05) in ATRA for genetic low-risk patients according to ELN recommendations. The clinical trial is registered at clinicaltrialsregister.eu (EudraCT Number: 2004-004321-95).
Highlights
• Up-to-date overview on developing new medications including candidates with novel bioloigical targets for the treatment of anxiety disorders and PTSD.
• Targeting glutamatergic, cholinergic and neurosteroid mechanisms can produce acute anxiolytic effects.
• Drugs, including psychedelics, are hypothesized to produce neuroplasticity to cause enduring clinical effects.
• Combining medication with psychological approaches may augment therapeutic efficacy.
• Advances in circuit neuroscience can be leveraged to inform the design of rationale drug targets.
Abstract
Psychiatric disorders associated with psychological trauma, stress and anxiety are a highly prevalent and increasing cause of morbidity worldwide. Current therapeutic approaches, including medication, are effective in alleviating symptoms of anxiety disorders and posttraumatic stress disorder (PTSD), at least in some individuals, but have unwanted side-effects and do not resolve underlying pathophysiology. After a period of stagnation, there is renewed enthusiasm from public, academic and commercial parties in designing and developing drug treatments for these disorders. Here, we aim to provide a snapshot of the current state of this field that is written for neuropharmacologists, but also practicing clinicians and the interested lay-reader. After introducing currently available drug treatments, we summarize recent/ongoing clinical assessment of novel medicines for anxiety and PTSD, grouped according to primary neurochemical targets and their potential to produce acute and/or enduring therapeutic effects. The evaluation of putative treatments targeting monoamine (including psychedelics), GABA, glutamate, cannabinoid, cholinergic and neuropeptide systems, amongst others, are discussed. We emphasize the importance of designing and clinically assessing new medications based on a firm understanding of the underlying neurobiology stemming from the rapid advances being made in neuroscience. This includes harnessing neuroplasticity to bring about lasting beneficial changes in the brain rather than – as many current medications do – produce a transient attenuation of symptoms, as exemplified by combining psychotropic/cognitive enhancing drugs with psychotherapeutic approaches. We conclude by noting some of the other emerging trends in this promising new phase of drug development.
Allogeneic hematopoietic cell transplantation (allo-HCT) is increasingly used in older myelofibrosis (MF) patients, but its risk/benefit ratio compared to non-transplant approaches has not been evaluated in this population. We analyzed the outcomes of allo-HCT in 556 MF patients aged ≥65 years from the EBMT registry, and determined the excess mortality over the matched general population of MF patients ≥65 years managed with allo-HCT (n = 556) or conventional drug treatment (n = 176). The non-transplant cohort included patients with intermediate-2 or high risk DIPSS from the Spanish Myelofibrosis Registry. After a median follow-up of 3.4 years, the estimated 5-year survival rate, non-relapse mortality (NRM), and relapse incidence after transplantation was 40%, 37%, and 25%, respectively. Busulfan-based conditioning was associated with decreased mortality (HR: 0.7, 95% CI: 0.5–0.9) whereas the recipient CMV+/donor CMV- combination (HR: 1.7, 95% CI: 1.2–2.4) and the JAK2 mutated genotype (HR: 1.9, 95% CI: 1.1–3.5) predicted higher mortality. Busulfan-based conditioning correlated with improved survival due to less NRM, despite its higher relapse rate when compared with melphalan-based regimens. Excess mortality was higher in transplanted patients than in the non-HCT cohort in the first year of follow-up (ratio: 1.93, 95% CI: 1.13–2.80), whereas the opposite occurred between the fourth and eighth follow-up years (ratio: 0.31, 95% CI: 0.18–0.53). Comparing the excess mortality of the two treatments, male patients seemed to benefit more than females from allo-HCT, mainly due to their worse prognosis with non-transplant approaches. These findings could potentially enhance counseling and treatment decision-making in elderly transplant-eligible MF patients.
Allogeneic hematopoietic stem cell transplantation for congenital immune dysregulatory disorders
(2019)
Primary immunodeficiency disorders that predominantly affect immune regulation and mechanisms of self-tolerance have come into the limelight, because at least for a subgroup of monogenetic disorders, a targeted therapy has become available. Nevertheless, their management often involves the treatment of severely compromising, refractory, multi-organ autoimmunity, leading to further increased susceptibility to infections and complications of long-term immune suppressive treatment, including the risk of malignancy. While evidence for allogeneic hematopoietic stem cell transplantation (alloHSCT) as a curative treatment option for severely affected patients by this disease category accumulates, clear indications, and guidelines for alloHSCT are lacking. Predictive and stratification-relevant tools such as disease activity scores are largely missing and often there is not a consistent genotype-phenotype correlation within the same family to facilitate the decision whether to transplant or not. In this review, we provide a literature-based update on indications and outcomes of alloHSCT for congenital immune dysregulative inborn errors of immunity according to the IUIS classification 2017.
Background: Because of limitations of transportation imposed by the COVID-19 pandemic, current recommendation calls for cryopreservation of allogeneic stem cell transplants before patient conditioning. A single cell therapy laboratory was selected to function as the central cryopreservation hub for all European registry donor transplants intended for the Australian-Pacific region. We examined properties of these transplants to ascertain how quality is maintained.
Methods: We analyzed 100 pandemic-related allogeneic mobilized blood-derived stem cell apheresis products generated at 30 collection sites throughout Europe, shipped to and cryopreserved at our center between April and November of 2020. Products were shipped in the cool, subsequently frozen with DMSO as cryoprotectant. Irrespective of origin, all products were frozen within the prescribed shelf-life of 72 h.
Results: Prior to cryopreservation, viable stem cell and leukocyte count according to the collection site and our reference laboratory were highly concordant (r2 = 0.96 and 0.93, respectively) and viability was > 90% in all instances. Median nominal post-thaw recovery of viable CD34+ cells was 42%. Weakly associated with poorer CD34+ cell recovery was higher leukocyte concentration, but not time lag between apheresis or addition of cryopreservant, respectively, and start of freezing. The correlation between pre- and post-thaw CD34+ cell dose was high (r2 = 0.85), hence predictable. Neutrophil and platelet engraftment were prompt with no evidence of dose dependency within the range of administered cell doses (1.31–15.56 × 106 CD34+ cells/kg).
Conclusions: General cryopreservation of allogeneic stem cell transplants is feasible. While more than half of the CD34+ cell content is lost, the remaining stem cells ensure timely engraftment.
Background: Chronic myelogenous leukemia (CML) and Philadelphia chromosome-positive (Ph+) acute lymphatic leukemia (Ph + ALL) are caused by the t(9;22), which fuses BCR to ABL resulting in deregulated ABL-tyrosine kinase activity. The constitutively activated BCR/ABL-kinase "escapes" the auto-inhibition mechanisms of c-ABL, such as allosteric inhibition. The ABL-kinase inhibitors (AKIs) Imatinib, Nilotinib or Dasatinib, which target the ATP-binding site, are effective in Ph + leukemia. Another molecular therapy approach targeting BCR/ABL restores allosteric inhibition. Given the fact that all AKIs fail to inhibit BCR/ABL harboring the 'gatekeeper' mutation T315I, we investigated the effects of AKIs in combination with the allosteric inhibitor GNF2 in Ph + leukemia.
Methods: The efficacy of this approach on the leukemogenic potential of BCR/ABL was studied in Ba/F3 cells, primary murine bone marrow cells, and untransformed Rat-1 fibroblasts expressing BCR/ABL or BCR/ABL-T315I as well as in patient-derived long-term cultures (PDLTC) from Ph + ALL-patients.
Results: Here, we show that GNF-2 increased the effects of AKIs on unmutated BCR/ABL. Interestingly, the combination of Dasatinib and GNF-2 overcame resistance of BCR/ABL-T315I in all models used in a synergistic manner.
Conclusions: Our observations establish a new approach for the molecular targeting of BCR/ABL and its resistant mutants using a combination of AKIs and allosteric inhibitors.
Alcoholism is one of the leading and increasingly prevalent reasons of liver associated morbidity and mortality worldwide. Alcoholic hepatitis (AH) constitutes a severe disease with currently no satisfying treatment options. Lipoxin A4 (LXA4), a 15-lipoxygenase (ALOX15)-dependent lipid mediator involved in resolution of inflammation, showed promising pre-clinical results in the therapy of several inflammatory diseases. Since inflammation is a main driver of disease progression in alcoholic hepatitis, we investigated the impact of endogenous ALOX15-dependent lipid mediators and exogenously applied LXA4 on AH development. A mouse model for alcoholic steatohepatitis (NIAAA model) was tested in Alox12/15+/+ and Alox12/15−/− mice, with or without supplementation of LXA4. Absence of Alox12/15 aggravated parameters of liver disease, increased hepatic immune cell infiltration in AH, and elevated systemic neutrophils as a marker for systemic inflammation. Interestingly, i.p. injections of LXA4 significantly lowered transaminase levels only in Alox12/15−/− mice and reduced hepatic immune cell infiltration as well as systemic inflammatory cytokine expression in both genotypes, even though steatosis progressed. Thus, while LXA4 injection attenuated selected parameters of disease progression in Alox12/15−/− mice, its beneficial impact on immunity was also apparent in Alox12/15+/+ mice. In conclusion, pro-resolving lipid mediators may be beneficial to reduce inflammation in alcoholic hepatitis.
While interleukin (IL)-1β is a potent pro-inflammatory cytokine involved in host defense, high levels can cause life-threatening sterile inflammation including systemic inflammatory response syndrome. Hence, the control of IL-1β secretion is of outstanding biomedical importance. In response to a first inflammatory stimulus such as lipopolysaccharide, pro-IL-1β is synthesized as a cytoplasmic inactive pro-form. Extracellular ATP originating from injured cells is a prototypical second signal for inflammasome-dependent maturation and release of IL-1β. The human anti-protease alpha-1 antitrypsin (AAT) and IL-1β regulate each other via mechanisms that are only partially understood. Here, we demonstrate that physiological concentrations of AAT efficiently inhibit ATP-induced release of IL-1β from primary human blood mononuclear cells, monocytic U937 cells, and rat lung tissue, whereas ATP-independent IL-1β release is not impaired. Both, native and oxidized AAT are active, suggesting that the inhibition of IL-1β release is independent of the anti-elastase activity of AAT. Signaling of AAT in monocytic cells involves the lipid scavenger receptor CD36, calcium-independent phospholipase A2β, and the release of a small soluble mediator. This mediator leads to the activation of nicotinic acetylcholine receptors, which efficiently inhibit ATP-induced P2X7 receptor activation and inflammasome assembly. We suggest that AAT controls ATP-induced IL-1β release from human mononuclear blood cells by a novel triple-membrane-passing signaling pathway. This pathway may have clinical implications for the prevention of sterile pulmonary and systemic inflammation.
The presynaptic protein alpha-synuclein has received much attention because its gain-of-function is associated with Parkinson’s disease. However, its physiological function is still poorly understood. We studied brain regions of knock-out mice at different ages with regard to consistent upregulations of the transcriptome and focused on glyoxalase I (GLO1). The microarray data were confirmed in qPCR, immunoblot, enzyme activity, and behavior analyses. GLO1 induction is a known protective cellular response to glucose stress, representing efforts to decrease toxic levels of methylglyoxal (MG), glyoxal and advanced glycation endproducts (AGEs). Mass spectrometry quantification demonstrated a ubiquitous increase in MG and fructosyl-lysine as consequences of glucose toxicity, and consistent enhancement of certain AGEs. Thus, GLO1 induction in KO brain seems insufficient to prevent AGE formation. In conclusion, the data demonstrate GLO1 expression and glycation damage to be induced by alpha-synuclein ablation. We propose that wild-type alpha-synuclein modulates brain glucose metabolism.
The crystal structure of the bovine Rieske iron-sulfur protein indicates a sulfur atom (S-1) of the iron-sulfur cluster and the sulfur atom (Sgamma) of a cysteine residue that coordinates one of the iron atoms form hydrogen bonds with the hydroxyl groups of Ser-163 and Tyr-165, respectively. We have altered the equivalent Ser-183 and Tyr-185 in the Saccharomyces cerevisiae Rieske iron-sulfur protein by site-directed mutagenesis of the iron-sulfur protein gene to examine how these hydrogen bonds affect the midpoint potential of the iron-sulfur cluster and how changes in the midpoint potential affect the activity of the enzyme. Eliminating the hydrogen bond from the hydroxyl group of Ser-183 to S-1 of the cluster lowers the midpoint potential of the cluster by 130 mV, and eliminating the hydrogen bond from the hydroxyl group of Tyr-185 to Sgamma of Cys-159 lowers the midpoint potential by 65 mV. Eliminating both hydrogen bonds has an approximately additive effect, lowering the midpoint potential by 180 mV. Thus, these hydrogen bonds contribute significantly to the positive midpoint potential of the cluster but are not essential for its assembly. The activity of the bc1 complex decreases with the decrease in midpoint potential, confirming that oxidation of ubiquinol by the iron-sulfur protein is the rate-limiting partial reaction in the bc1 complex, and that the rate of this reaction is extensively influenced by the midpoint potential of the iron-sulfur cluster.
Highlights
• A big dataset reveals age-related alterations in EEG biomarkers and cognition.
• Prominent decline of individual alpha peak frequency primarily in temporal lobes.
• A positive association between individual alpha peak frequency and working memory.
• Absence of age-related alpha power decline when controlling for 1/f decay of the PSD.
• Alpha power is negatively associated with the speed of processing in elderly sample.
Abstract
While many structural and biochemical changes in the brain have previously been associated with older age, findings concerning functional properties of neuronal networks, as reflected in their electrophysiological signatures, remain rather controversial. These discrepancies might arise due to several reasons, including diverse factors determining general spectral slowing in the alpha frequency range as well as amplitude mixing between the rhythmic and non-rhythmic parameters. We used a large dataset (N = 1703, mean age 70) to comprehensively investigate age-related alterations in multiple EEG biomarkers taking into account rhythmic and non-rhythmic activity and their individual contributions to cognitive performance. While we found strong evidence for an individual alpha peak frequency (IAF) decline in older age, we did not observe a significant relationship between theta power and age while controlling for IAF. Not only did IAF decline with age, but it was also positively associated with interference resolution in a working memory task primarily in the right and left temporal lobes suggesting its functional role in information sampling. Critically, we did not detect a significant relationship between alpha power and age when controlling for the 1/f spectral slope, while the latter one showed age-related alterations. These findings thus suggest that the entanglement of IAF slowing and power in the theta frequency range, as well as 1/f slope and alpha power measures, might explain inconsistencies reported previously in the literature. Finally, despite the absence of age-related alterations, alpha power was negatively associated with the speed of processing in the right frontal lobe while 1/f slope showed no consistent relationship to cognitive performance. Our results thus demonstrate that multiple electrophysiological features, as well as their interplay, should be considered for the comprehensive assessment of association between age, neuronal activity, and cognitive performance.