Predicting Successful Weaning from Mechanical Ventilation by Reduction in Positive End-expiratory Pressure Level Using Machine Learning.

Weaning patients from mechanical ventilation (MV) is a critical and resource intensive process in the Intensive Care Unit (ICU) that impacts patient outcomes and healthcare expenses. Weaning methods vary widely among providers. Prolonged MV is associated with adverse events and higher healthcare expenses. Predicting weaning readiness is a non-trivial process in which the positive end-expiratory pressure (PEEP), a crucial component of MV, has potential to be indicative but has not yet been used as the target. We aimed to predict successful weaning from mechanical ventilation by targeting changes in the PEEP-level using a supervised machine learning model. This retrospective study included 12,153 mechanically ventilated patients from Medical Information Mart for Intensive Care (MIMIC-IV) and eICU collaborative research database (eICU-CRD). Two machine learning models (Extreme Gradient Boosting and Logistic Regression) were developed using a continuous PEEP reduction as target. The data is splitted into 80% as training set and 20% as test set. The model's predictive performance was reported using 95% confidence interval (CI), based on evaluation metrics such as area under the receiver operating characteristic (AUROC), area under the precision-recall curve (AUPRC), F1-Score, Recall, positive predictive value (PPV), and negative predictive value (NPV). The model's descriptive performance was reported as the variable ranking using SHAP (SHapley Additive exPlanations) algorithm. The best model achieved an AUROC of 0.84 (95% CI 0.83-0.85) and an AUPRC of 0.69 (95% CI 0.67-0.70) in predicting successful weaning based on the PEEP reduction. The model demonstrated a Recall of 0.85 (95% CI 0.84-0.86), F1-score of 0.86 (95% CI 0.85-0.87), PPV of 0.87 (95% CI 0.86-0.88), and NPV of 0.64 (95% CI 0.63-0.66). Most of the variables that SHAP algorithm ranked to be important correspond with clinical intuition, such as duration of MV, oxygen saturation (SaO2), PEEP, and Glasgow Coma Score (GCS) components. This study demonstrates the potential application of machine learning in predicting successful weaning from MV based on continuous PEEP reduction. The model's high PPV and moderate NPV suggest that it could be a useful tool to assist clinicians in making decisions regarding ventilator management.

Predicting Hypoxia Using Machine Learning: Systematic Review.

Background: Hypoxia is an important risk factor and indicator for the declining health of inpatients. Predicting future hypoxic events using machine learning is a prospective area of study to facilitate time-critical interventions to counter patient health deterioration. Objective: This systematic review aims to summarize and compare previous efforts to predict hypoxic events in the hospital setting using machine learning with respect to their methodology, predictive performance, and assessed population. Methods: A systematic literature search was performed using Web of Science, Ovid with Embase and MEDLINE, and Google Scholar. Studies that investigated hypoxia or hypoxemia of hospitalized patients using machine learning models were considered. Risk of bias was assessed using the Prediction Model Risk of Bias Assessment Tool. Results: After screening, a total of 12 papers were eligible for analysis, from which 32 models were extracted. The included studies showed a variety of population, methodology, and outcome definition. Comparability was further limited due to unclear or high risk of bias for most studies (10/12, 83%). The overall predictive performance ranged from moderate to high. Based on classification metrics, deep learning models performed similar to or outperformed conventional machine learning models within the same studies. Models using only prior peripheral oxygen saturation as a clinical variable showed better performance than models based on multiple variables, with most of these studies (2/3, 67%) using a long short-term memory algorithm. Conclusions: Machine learning models provide the potential to accurately predict the occurrence of hypoxic events based on retrospective data. The heterogeneity of the studies and limited generalizability of their results highlight the need for further validation studies to assess their predictive performance.

[The situation in the German forensic commitment-Results of a survey by the DGPPN]. / Die Situation des deutschen Maßregelvollzugs ­ Ergebnisse einer Umfrage der DGPPN.

BACKGROUND AND OBJECTIVE: In German forensic psychiatry detention under Sections 63 and 64 of the German Penal Code have been repeatedly reformed over the past years; however, despite the most recent amendments to the law on detention, clinics and state authorities warn of insufficient capacities and worrying conditions. Media reports paint a defiant picture. At the same time, there is a lack of valid data that would allow an objective description of the situation in forensic psychiatry. Against this background the management of institutions in Germany has been surveyed. MATERIAL AND METHODS: The survey was conducted as an online survey and sent to all 78 forensic hospitals in Germany. The survey covered topics such as structural data of the facilities, the occupancy and staffing situation, incidents, support from supervisory authorities and funding agencies, and patient characteristics. The results are presented descriptively. RESULTS: Of the 78 facilities contacted, 45 (approximately 60%) participated at least partially in the survey. Many of the clinics (68.5%) complained of significant overcrowding. A clear lack of staff and rooms was reported, at the same time it was stated that patients do not receive adequate treatment. Approximately 1 in 5 patients have a length of stay for more than 10 years and one third of the clinics reported an increasing number of physical assaults by patients. CONCLUSION: This overview shows that the forensic psychiatric hospitals are in very different but generally strained situations. A significant number of clinics are under great pressure. Financial, structural, spatial and personnel resources were described as insufficient to properly and professionally fulfill the legal mandate. The treatment standards presented by the DGPPN in 2017 are not met in many clinics.

The Effects of Climate Change on Mental Health.

BACKGROUND: All over the world, climate change is exerting negative and complex effects on human living conditions and health. In this narrative review, we summarize the current global evidence regarding the effects of climate change on mental health. METHODS: A systematic literature search concerning the direct effects of acute extreme weather events (floods, storms, fires) and chronic stresses (heat, drought) due to climate change, as well as the indirect effects of climate change (food insecurity, migration), on the diagnoses of mental disorders, psychological distress, and psychiatric emergency admissions was carried out in PubMed and PsychInfo, and supplemented by expert selection. 1017 studies were identified, and 128 were included. RESULTS: The heterogeneity of study methods does not permit any overall estimate of effect strength. The available evidence shows that traumatic experiences due to extreme weather events increase the risk of affective and anxiety disorders, especially the risk of post-traumatic stress disorder. Heat significantly increases the morbidity and mortality attributable to mental illness, as well as the frequency of psychiatric emergencies. Persistent stressors such as drought, food insecurity, and migration owing to climate change can also be major risk factors for mental illness. CONCLUSION: The consequences of climate change are stress factors for mental health. Therefore, as global warming progresses, an increasing incidence and prevalence of mental illness is to be expected. Vulnerable groups, such as the (already) mentally ill, children, and adolescents, need to be protected. At the same time, there is a need for further systematic research on the mechanisms of action and effects of climate change on mental function.

[Efficiency-Focussed Assessment of Internet-Based Interventions: a Study Protocol]. / Wirksamkeitsfokussierte Bewertung von internetbasierten Interventionen: ein Studienprotokoll.

BACKGROUND: The availability of internet-based interventions for the treatment of mental disorder is steadily growing and is also included in the German health care system. However, there is still room for improvement in terms of the information available to users and practitioners, particularly with regard to the effectiveness of internet-based interventions. OBJECTIVES: To identify and evaluate internet-based interventions for the treatment of mental disorder, listed in the DiGA-Verzeichnis. A user-friendly description of positively evaluated interventions will be made available for interested people at psychenet.de. METHODS: By means of predefined criteria for intervention identification, evaluation and subsequent publication on psychenet.de, a methodological sound and transparent procedure will be established and put into practice. ETHICS AND DISSEMINATION: Ethics approval is not required for this study, as research on secondary data was conducted. Relevant professional, stakeholder and patient associations will be informed about the information offered at psychenet.de.

Editor's Choice - Association Between Peri-OPerative Aspirin ResisTance and CardioVascular Outcome (POPART-CVO): a Prospective Non-Interventional Cohort Study.

OBJECTIVE: New onset aspirin resistance during surgery, known as peri-operative aspirin resistance, is observed in up to 30% of vascular surgery patients and is associated with post-operative myocardial damage; questioning aspirin effectiveness towards peri-operative cardiovascular events. The objective of this study was to prospectively evaluate whether peri-operative aspirin resistance in vascular surgery is associated with an adverse cardiovascular outcome. METHODS: Based on a sample size calculation, 194 adult elective vascular or endovascular surgery patients receiving aspirin were analysed in this prospective, single centred, non-interventional cohort study. Platelet function was measured before surgery, one hour after incision, four hours post-operatively, and on the morning of the first and second post-operative days using the Multiplate analyser. The primary outcome was myocardial injury after non-cardiac surgery (MINS). Secondary outcomes included major bleeding, admission to intensive care unit, length of hospital stay, and major adverse cardiac and cerebrovascular events. Subgroup analyses were performed for patients with different cardiovascular risk and for patients who underwent endovascular surgery. RESULTS: Peri-operative aspirin resistance was observed in 27.8% of patients but was not associated with MINS (27.8% vs. 32.1%, aspirin resistance vs. no aspirin resistance, OR 0.812, 95% CI 0.406 - 1.624, p = .56) or with any of the secondary endpoints (all p > .050). In nine of the 10 subgroup analyses, aspirin resistance was not associated with a difference in MINS rate. However, in patients with a low cardiovascular risk profile (RCRI 0-2), MINS occurred more frequently in patients without aspirin resistance (p = .049). CONCLUSION: This study confirmed previous reports demonstrating that peri-operative aspirin resistance is common in patients undergoing vascular or endovascular surgery. However, in patients who continue aspirin throughout the peri-operative period, aspirin resistance is a phenomenon, which does not appear to be related to MINS. Measuring peri-operative platelet function using the Multiplate analyser with the intention to identify and potentially prevent or treat peri-operative aspirin resistance seems to be dispensable.

Effect of Intraoperative Handovers of Anesthesia Care on Mortality, Readmission, or Postoperative Complications Among Adults: The HandiCAP Randomized Clinical Trial.

Importance: Intraoperative handovers of anesthesia care are common. Handovers might improve care by reducing physician fatigue, but there is also an inherent risk of losing critical information. Large observational analyses report associations between handover of anesthesia care and adverse events, including higher mortality. Objective: To determine the effect of handovers of anesthesia care on postoperative morbidity and mortality. Design, Setting, and Participants: This was a parallel-group, randomized clinical trial conducted in 12 German centers with patients enrolled between June 2019 and June 2021 (final follow-up, July 31, 2021). Eligible participants had an American Society of Anesthesiologists physical status 3 or 4 and were scheduled for major inpatient surgery expected to last at least 2 hours. Interventions: A total of 1817 participants were randomized to receive either a complete handover to receive anesthesia care by another clinician (n = 908) or no handover of anesthesia care (n = 909). None of the participating institutions used a standardized handover protocol. Main Outcomes and Measures: The primary outcome was a 30-day composite of all-cause mortality, hospital readmission, or serious postoperative complications. There were 19 secondary outcomes, including the components of the primary composite, along with intensive care unit and hospital lengths of stay. Results: Among 1817 randomized patients, 1772 (98%; mean age, 66 [SD, 12] years; 997 men [56%]; and 1717 [97%] with an American Society of Anesthesiologists physical status of 3) completed the trial. The median total duration of anesthesia was 267 minutes (IQR, 206-351 minutes), and the median time from start of anesthesia to first handover was 144 minutes in the handover group (IQR, 105-213 minutes). The composite primary outcome occurred in 268 of 891 patients (30%) in the handover group and in 284 of 881 (33%) in the no handover group (absolute risk difference [RD], -2.5%; 95% CI, -6.8% to 1.9%; odds ratio [OR], 0.89; 95% CI, 0.72 to 1.10; P = .27). Nineteen of 889 patients (2.1%) in the handover group and 30 of 873 (3.4%) in the no handover group experienced all-cause 30-day mortality (absolute RD, -1.3%; 95% CI, -2.8% to 0.2%; OR, 0.61; 95% CI, 0.34 to 1.10; P = .11); 115 of 888 (13%) vs 136 of 872 (16%) were readmitted to the hospital (absolute RD, -2.7%; 95% CI, -5.9% to 0.6%; OR, 0.80; 95% CI, 0.61 to 1.05; P = .12); and 195 of 890 (22%) vs 189 of 874 (22%) experienced serious postoperative complications (absolute RD, 0.3%; 95% CI, -3.6% to 4.1%; odds ratio, 1.02; 95% CI, 0.81 to 1.28; P = .91). None of the 19 prespecified secondary end points differed significantly. Conclusions and Relevance: Among adults undergoing extended surgical procedures, there was no significant difference between the patients randomized to receive handover of anesthesia care from one clinician to another, compared with the no handover group, in the composite primary outcome of mortality, readmission, or serious postoperative complications within 30 days. Trial Registration: ClinicalTrials.gov Identifier: NCT04016454.

Online therapy: an added value for inpatient routine care? Perspectives from mental health care professionals.

Internet-delivered interventions can be effective in treating mental disorders. However, their rate of use in German psychiatric inpatient routine care is low. The current study aimed to investigate the attitude of mental health care professionals working in inpatient care regarding internet-delivered interventions, including presumed benefits, barriers and facilitators. In total, 176 health professionals from ten inpatient psychiatric hospitals throughout Germany were surveyed on site. The professionals' attitude towards internet-delivered interventions in inpatient care was assessed by an adapted version of the 'Attitude toward Telemedicine in Psychiatry and Psychotherapy' (ATTiP) questionnaire. To identify benefits, barriers and facilitators, we developed open-response questions that were based on the 'Unified Theory of Acceptance and Use of Technology' (UTAUT) and analyzed by a qualitative content analysis. Professionals reported little experience or knowledge about internet-delivered interventions. Their attitude towards internet-delivered interventions in psychiatric inpatient care was rather indifferent. The most frequently mentioned potential benefits were an optimised treatment structure and patient empowerment; the most frequently anticipated barriers were too severe symptoms of patients, the feared neglect of face-to-face contacts and insufficient technical equipment; and the most frequently mentioned facilitators were high usability of the internet-based intervention, a sufficient functional level of the patient and further education of staff. For successful implementation in the inpatient sector, internet-delivered interventions must be adapted to the special needs of severely mentally ill patients and to the hospital management systems and workflow. In addition, technical preconditions (internet access, devices) must be met. Last, further education of mental health care professionals is needed.

[Digital health applications (DiGA) in medical and psychotherapeutic care. Opportunities and challenges from the perspective of the healthcare providers]. / Digitale Gesundheitsanwendungen (DiGA) in der ärztlichen und psychotherapeutischen Versorgung. Chancen und Herausforderungen aus Sicht der Leistungserbringer.

Since 2019, insured persons have a right by law to receive a prescription of digital health applications (DiGA). DiGA can be used in a variety of ways. Most healthcare providers are receptive to the possibilities of integration of DiGA into their treatment. In particular, the promotion of patient empowerment through DiGA is seen as a potential advantage by physicians and psychotherapists.However, from the healthcare provider's view, the preconditions for a successful integration of DiGA into the healthcare system are not yet fulfilled. The most important challenge that remains to be solved is the creation of acceptance and trust in a careful, producer-independent quality inspection of DiGA. Verified evidence on the effectiveness, interoperability, and data security of DiGA, as well as on the additional workload for providers, should be transparently available before they can be prescribed to patients. Furthermore, findings from health services research on the optimal integration of a DiGA into clinical workflow should be generated and integrated into the regulations. In addition, DiGA should be prescribed only if individual circumstances of the patient were considered.

Comparison of Lung Ultrasound versus Chest X-ray for Detection of Pulmonary Infiltrates in COVID-19.

Point-of-care lung ultrasound (LUS) is an attractive alternative to chest X-ray (CXR), but its diagnostic accuracy compared to CXR has not been well studied in coronavirus disease 2019 (COVID-19) patients. We conducted a prospective observational study to assess the correlation between LUS and CXR findings in COVID-19 patients. Ninety-six patients with a clinical diagnosis of COVID-19 underwent an LUS exam and CXR upon presentation. Physicians blinded to the CXR findings performed all LUS exams. Detection of pulmonary infiltrates by CXR versus LUS was compared between patients categorized as suspected or confirmed COVID-19 based on reverse transcriptase-polymerase chain reaction. Sensitivities and correlation by Kappa statistic were calculated between LUS and CXR. LUS detected pulmonary infiltrates more often than CXR in both suspected and confirmed COVID-19 subjects. The most common LUS abnormalities were discrete B-lines, confluent B-lines, and small subpleural consolidations. Most important, LUS detected unilateral or bilateral pulmonary infiltrates in 55% of subjects with a normal CXR. Substantial agreement was demonstrated between LUS and CXR for normal, unilateral or bilateral findings (Κ = 0.48 (95% CI 0.34 to 0.63)). In patients with suspected or confirmed COVID-19, LUS detected pulmonary infiltrates more often than CXR, including more than half of the patients with a normal CXR.

The MBOAT7 rs641738 variant is associated with an improved outcome in primary sclerosing cholangitis.

BACKGROUND AND AIMS: Primary sclerosing cholangitis (PSC) is a chronic cholestatic disease that causes liver cirrhosis, leading to liver failure. Additionally, PSC is a risk factor for cholangiocarcinoma. Its mechanism is unknown, and liver transplantation remains the sole curative option. The membrane bound O-acyltransferase domain containing 7 (MBOAT7) rs641738 and rs626283 variant alleles have been associated with both an accelerated progression of the disease and a higher risk for developing a more severe phenotype in many chronic hepatic diseases. Thus, we analysed their effect on long-term outcomes and laboratory parameters in PSC patients. METHODS: We determined MBOAT7 genotypes and estimated the actuarial survival rate free of liver transplantation, using the Kaplan-Meier estimator. The differences between the estimates were analysed using the log-rank test. Patient blood was drawn and analysed for different serum parameters including cholestatic markers. Additionally, MBOAT7 RNA expression in human hepatic cell lines MZCHA1 (a biliary adenocarcinoma cell line), HepG2 (a hepatocellular carcinoma cell line), LX-2 (hepatic stellate cell line) and H-69 (cholangiocyte cell line) was analysed. RESULTS: Transplant-free survival was significantly prolonged in carriers of two rs641738 variant alleles, which was referred to as the TT genotype (mean 19.6 years; 95% confidence interval [CI]: 16.3-22.9 years) compared to the CC (mean 15.4 years, 95% CI 12.8-18.0 years) and heterozygous genotypes (mean 13.2 years, 95% CI 11.4-15.0 years) (P=0.017). This effect was restricted to male patients. We confirmed the high expression of MBOAT7 in hepatic stellate cells and found that MBOAT7 is less expressed in biliary epithelial cell lines, compared to parenchymal hepatic cells. CONCLUSIONS: Unlike other chronic liver diseases, carrying two MBOAT7 variant alleles does not seem to affect PSC patients negatively, but seems to have a positive effect on transplant-free survival. This study could help improve individual prognosis in PSC patients and give some new perspective on the involvement of the immune system in PSC.

[Finding the needles in the haystack: quality criteria for the use of internet-based self-management interventions in the prevention and treatment of mental disorders]. / Die Nadeln im Heuhaufen finden: Qualitätskriterien für den Einsatz von internetbasierten Selbstmanagement-Interventionen in Prävention und Behandlung psychischer Störungen.

Numerous self-management interventions have proven to be efficacious in the treatment of a number of mental disorders in randomized trials. However, these interventions have not yet reached clinical routine everywhere. Among other things, this is due to the fact that, in addition to the evidence-based interventions, other interventions are offered that have never been scientifically investigated, and in some cases, do not even rely on evidence-based methods of psychotherapy. The present quality criteria, developed by the two professional associations DGPs and DGPPN, are intended to help patients, practitioners and decision-makers in the health care sector to identify safe and efficacious interventions. The core quality criteria cover the following aspects: safety of patients and their data; ensuring therapeutic quality by using evidence-based psychotherapeutic methods and developing the intervention in liaison with licensed psychotherapists or medical specialists; the presence of proof of efficacy from at least one randomized trial; and transparency regarding key information, e. g., the cost of the intervention. We hope that these criteria can contribute to the inclusion of self-management interventions in the range of services covered by statutory health insurance companies.

Getting together: Social contact frequency across the life span.

Frequent social interactions are strongly linked to positive affect, longevity, and good health. Although there has been extensive research on changes in the size of social networks over time, little attention has been given to the development of contact frequency across the life span. In this cohort-sequential longitudinal study, we examined intraindividual changes in the frequency of social contact with family and nonfamily members, and potential moderators of these changes. The data come from the 1998, 2003, 2008, and 2013 waves of the German Socio-Economic Panel (SOEP) study (N = 36,716; age range: 17-85 years). Using latent growth curve analysis, we found that the frequency of in-person contact with family members remained relatively stable across the life span. In contrast, the frequency of visits to and from nonfamily members (neighbors, friends, and acquaintances) declined following a cubic trajectory and dropped below the frequency of family visits when respondents were in their mid-30s. Relationship status and gender had a slight effect on both of these relationship trajectories. Subjective current health status and employment status influenced the life span trajectory of nonfamily social contact only. Changes of residence and the birth of a child, both of which constitute major turning points in the life course, did not affect the life span trajectory of either family or nonfamily in-person contact. The findings are discussed here in the context of earlier findings and in relation to socioemotional selectivity and social convoy theory and the evolutionary life history approach. (PsycINFO Database Record

Long-Term Effects of an Extensive Cognitive Training on Personality Development.

Previous research found that cognitive training increases the Big Five personality trait Openness to Experience during and some weeks after the intervention. The present study investigated whether long-term changes happen in Openness to Experience and other personality traits after an extensive cognitive training of memory and perceptual speed. The intervention group consisted of 204 adults (20-31 years and 65-80 years; 50% female) who received daily 1-hour cognitive training sessions for about 100 days. The control group consisted of 86 adults (21-29 years and 65-82 years; 51% female) who received no cognitive training. All participants answered the NEO Five-Factor Inventory before and 2 years after the cognitive training. Latent change models were applied that controlled for age group (young vs. old) and gender. In the long run, the cognitive training did not affect changes in any facet of Openness to Experience. This was true for young and old participants as well as for men and women. Instead, the cognitive training lowered the general increase of Conscientiousness. Even an extensive cognitive training on memory and perceptual speed does not serve as a sufficient intervention for enduring changes in Openness to Experiences or one of its facets.

RAnoLazIne for the treatment of diastolic heart failure in patients with preserved ejection fraction: the RALI-DHF proof-of-concept study.

OBJECTIVES: This study investigated whether inhibiting late Na(+) current by using ranolazine improved diastolic function in patients with heart failure with preserved ejection fraction (HFpEF). BACKGROUND: HFpEF accounts for >50% of all HF patients, but no specific treatment exists. METHODS: The RALI-DHF (RAnoLazIne for the Treatment of Diastolic Heart Failure) study was a prospective, randomized, double-blind, placebo-controlled small proof-of-concept study. Inclusion criteria were EF ≥45%, a mitral E-wave velocity/mitral annular velocity ratio (E/E') >15 or N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentration >220 pg/ml, a left ventricular end-diastolic pressure (LVEDP) ≥18 mm Hg, and time-constant of relaxation (tau) ≥50 ms. Patients were randomized to ranolazine (n = 12) or placebo (n = 8). Treatment consisted of intravenous infusion for 24 h, followed by oral treatment for 13 days. RESULTS: After 30 min of infusion, LVEDP (p = 0.04) and pulmonary capillary wedge pressure (p = 0.04) decreased in the ranolazine group but not in the placebo group. Mean pulmonary artery pressure showed a trend toward a decrease in the ranolazine group that was significant under pacing conditions at 120 beats/min (p = 0.02), but not for the placebo group. These changes occurred without changes in left ventricular end-systolic pressure or systemic or pulmonary resistance but in the presence of a small but significant decrease in cardiac output (p = 0.04). Relaxation parameters (e.g., tau, rate of decline of left ventricular pressure per minute [dP/dtmin]) were unaltered. Echocardiographically, the E/E' ratio did not significantly change after 22 h. After 14 days of treatment, no significant changes were observed in echocardiographic or cardiopulmonary exercise test parameters. There were no significant effects on NT-pro-BNP levels. CONCLUSIONS: Results of this proof-of-concept study revealed that ranolazine improved measures of hemodynamics but that there was no improvement in relaxation parameters. (Ranolazine in Diastolic Heart Failure [RALI-DHF]; NCT01163734).

Detection of the water-binding sites of the oxygen-evolving complex of Photosystem II using W-band 17O electron-electron double resonance-detected NMR spectroscopy.

Water binding to the Mn(4)O(5)Ca cluster of the oxygen-evolving complex (OEC) of Photosystem II (PSII) poised in the S(2) state was studied via H(2)(17)O- and (2)H(2)O-labeling and high-field electron paramagnetic resonance (EPR) spectroscopy. Hyperfine couplings of coordinating (17)O (I = 5/2) nuclei were detected using W-band (94 GHz) electron-electron double resonance (ELDOR) detected NMR and Davies/Mims electron-nuclear double resonance (ENDOR) techniques. Universal (15)N (I = ½) labeling was employed to clearly discriminate the (17)O hyperfine couplings that overlap with (14)N (I = 1) signals from the D1-His332 ligand of the OEC (Stich Biochemistry 2011, 50 (34), 7390-7404). Three classes of (17)O nuclei were identified: (i) one µ-oxo bridge; (ii) a terminal Mn-OH/OH(2) ligand; and (iii) Mn/Ca-H(2)O ligand(s). These assignments are based on (17)O model complex data, on comparison to the recent 1.9 Å resolution PSII crystal structure (Umena Nature 2011, 473, 55-60), on NH(3) perturbation of the (17)O signal envelope and density functional theory calculations. The relative orientation of the putative (17)O µ-oxo bridge hyperfine tensor to the (14)N((15)N) hyperfine tensor of the D1-His332 ligand suggests that the exchangeable µ-oxo bridge links the outer Mn to the Mn(3)O(3)Ca open-cuboidal unit (O4 and O5 in the Umena et al. structure). Comparison to literature data favors the Ca-linked O5 oxygen over the alternative assignment to O4. All (17)O signals were seen even after very short (≤15 s) incubations in H(2)(17)O suggesting that all exchange sites identified could represent bound substrate in the S(1) state including the µ-oxo bridge. (1)H/(2)H (I = ½, 1) ENDOR data performed at Q- (34 GHz) and W-bands complement the above findings. The relatively small (1)H/(2)H couplings observed require that all the µ-oxo bridges of the Mn(4)O(5)Ca cluster are deprotonated in the S(2) state. Together, these results further limit the possible substrate water-binding sites and modes within the OEC. This information restricts the number of possible reaction pathways for O-O bond formation, supporting an oxo/oxyl coupling mechanism in S(4).

Melatonin does not influence sleep deprivation electroencephalogram recordings in children.

UNLABELLED: The electroencephalogram (EEG) is an essential diagnostic tool in children with epilepsy. The recording of a sleep EEG can increase the yield of EEG recordings in certain epileptic syndromes. The primary aim of this study was to assess the influence of melatonin on EEG recording (quality, EEG characteristics) and to assess its efficacy to induce sleep. Children with epilepsy or non-epileptic neurological patients requiring sleep deprivation EEG studies were enrolled into this prospective study at a tertiary University Hospital study. Sequential recording of sleep deprivation EEGs both with and without prior administration of melatonin was performed. A total of 50 patients (27 with epilepsy, 23 non-epileptic neurological patients) were included in this study (median age 9.5 years; range 1-18 years; male 28). The quality and EEG characteristics (abnormal findings, depth of sleep) were not affected by the use of melatonin. In total, 92 of 100 EEGs were successfully performed without significant differences between the two groups (six failures with melatonin, two failures without melatonin; p = 0.289). CONCLUSIONS: We conclude that melatonin does not alter the quality of sleep EEG studies in children with epilepsy or suspected epilepsy. Melatonin does not increase the rate of successfully performed EEG studies in sleep-deprived children.

Dynamics of the cyanobacterial photosynthetic network: communication and modification of membrane protein complexes.

Cyanobacterial photosystem 2 and cytochrome b(6)f complexes have been structurally resolved up to the molecular level while the adjustment of their function in response to environmental and intracellular parameters is based on various modifications of these complexes which have not yet been resolved in detail. This minireview summarizes recent results on two central modifications for each complex: (a) for the cytochrome b(6)f complex the implication of PetP, a new subunit, and of three copies of PetC, the Rieske protein, for the fine-tuning of the photosynthetic electron transport is evaluated; (b) for photosystem 2, the heterogeneity of the D1 subunit and the role of subunit Psb27 is discussed in relation to stress response and the biogenesis/repair cycle. The presented "dynamic" models for both complexes should illustrate the need to complement structural by more extensive functional models which consider the flexibility of individual complexes in the physiological context - beyond structure.

Functional characterization and quantification of the alternative PsbA copies in Thermosynechococcus elongatus and their role in photoprotection.

The D1 protein (PsbA) of photosystem II (PSII) from Thermosynechococcus elongatus is encoded by a psbA gene family that is typical of cyanobacteria. Although the transcription of these three genes has been studied previously (Kós, P. B., Deák, Z., Cheregi, O., and Vass, I. (2008) Biochim. Biophys. Acta 1777, 74-83), the protein quantification had not been possible due to the high sequence identity between the three PsbA copies. The successful establishment of a method to quantify the PsbA proteins on the basis of reverse phase-LC-electrospray mass ionization-MS/MS (RP-LC-ESI-MS/MS) enables an accurate comparison of transcript and protein level for the first time ever. Upon high light incubation, about 70% PsbA3 could be detected, which closely corresponds to the transcript level. It was impossible to detect any PsbA2 under all tested conditions. The construction of knock-out mutants enabled for the first time a detailed characterization of both whole cells and also isolated PSII complexes. PSII complexes of the ΔpsbA1/psbA2 mutant contained only copy PsbA3, whereas only PsbA1 could be detected in PSII complexes from the ΔpsbA3 mutant. In whole cells as well as in isolated complexes, a shift of the free energy between the redox pairs in the PsbA3 complexes in comparison with PsbA1 could be detected by thermoluminescence and delayed fluorescence measurements. This change is assigned to a shift of the redox potential of pheophytin toward more positive values. Coincidentally, no differences in the Q(A)-Q(B) electron transfer could be observed in flash-induced fluorescence decay or prompt fluorescence measurements. In conclusion, PsbA3 complexes yield a better protection against photoinhibition due to a higher probability of the harmless dissipation of excess energy.