Determining ICU EEG periodic patterns and why it matters

Historically, periodic EEG patterns were described as any pattern with stereotyped paroxysmal complexes occurring at regular intervals, i.e., the period (T). T is the sum of the duration of the waveform (t1) and, eventually, the duration of the interval between two consecutive waves (t2). The American Clinical Neurophysiology Society introduced the concept of a clearly discernible inter-discharge interval between consecutive waveforms (i.e., t2). As this definition was not applied to what have previously been termed triphasic waves and in some cases of lateralized periodic discharges, we propose reconsideration of terminology that includes historical use of definitions. This will allow the development and usage of the concept for periodic EEG patterns as any runs of stereotyped paroxysmal waveforms separated by nearly identical intervals and prolonged repetitive complexes on the EEG. Prolonged expression means EEG is recorded for a sufficient period of time to prove that the pattern is repetitive, thus resulting in a monomorphic/monotonous pattern. More important than the inter-discharge interval (t2), periodic EEG patterns occur at time regular intervals (T). As a result, periodic EEG activity should be considered along a continuum and not the opposite of rhythmic EEG activity where no interval activity exists between consecutive waveforms.

Alterations in rhythmic and non-rhythmic resting-state EEG activity and their link to cognition in older age

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.

Novel climates in European river sub-basins pose a challenge for the persistence of freshwater fish

Understanding how climate change would affect biota inhabiting sensitive and highly valuable ecosystems, spanning broad regions, is essential to anticipate implications for biodiversity and humans, and to identify management and mitigation measures. Traditionally, assessments to evaluate climatic risks over broad regions and for many species implement models that allow the projection of a climate-driven redistribution of biodiversity. Still, the wealth and quality of the background information (e.g., species presence data) constrain the accuracy and representativeness of such frameworks. As an alternative, here, we developed a twofold approach to assess the vulnerability of 86 European freshwater fish. We accounted for shifts in a multidimensional climatic space of broader hydrological units that host freshwater bodies in Europe. We then linked metrics of their climatic stability with groups of species, which were generated from six intrinsic traits that shape species adaptive capacity to climate change. Our results demonstrated that the climate of all (n = 538) river sub-basins hosted in the European Union territory would change by 2100, with more than 10% of them being projected to gain completely novel climates. Sub-basins predicted to lose more than 90% of their current climatic space were mainly identified in the area around the Baltic Sea, but also in Mediterranean regions (i.e., Iberian Peninsula). Important numbers of fish species with life history strategies that are considered susceptible to climate change were identified in sub-basins that were predicted to completely lose their current climatic conditions. Clearly, the climate of valuable freshwater ecosystems is changing, affecting species and their communities in varying ways. The risk is high, and is not limited to specific regions; thus, new effective strategies and measures are needed to conserve freshwater fish and their habitats across Europe.

Childbirth with epidural analgesia in a pregnant woman with hypokalemic periodic paralysis

Familial hypokalaemic periodic paralysis (FHPP) is an uncommon genetic disease characterized by muscle weakness associated with hypokalaemia. Episodes are precipitated by drugs, stress, metabolic diseases, hypothermia or infection. We report the case of a 38-year-old pregnant women with FHPP who underwent epidural analgesia for labour. Pregnant women with FHPP require multidisciplinary management involving an anaesthesiologist, a gynaecologist and a paediatrician. It is important to maintain normothermia, prevent hyperventilation, monitor electrolytes, avoid glucose infusions and medications that cause hypokalaemia, and administer potassium supplements when required. Locoregional techniques should be preferred over general anaesthesia. Early epidural analgesia reduces the risk of pain that could trigger an episode of FHPP. In the case of general anaesthesia, drugs that can cause malignant hyperthermia should be avoided, and short-acting non-depolarizing neuromuscular blockers with blockade-depth monitoring should be used.

Netflow Python library - A free software tool for the generation and analysis of pore or flow networks

State-of-the-art tomographic scanning techniques provide detailed pore-space geometries of natural porous media, which are central for the study of subsurface flow and transport. Due to experimental and computational limitations, the extraction of high-resolution images is limited to relatively small sample volumes. To reduce the amount of data and the physical complexity, pore-space geometries are routinely translated into pore network models. Subsequently, such networks are expanded in space with suitable computational methods to determine effective medium parameters at larger scales relevant in engineering applications. While existing methods can provide networks with effective flow parameters being consistent with experimental data for comparably homogeneous media such as bead packs and sandstones, these methods are inadequate for more complex heterogeneous rocks such as carbonates or become too expensive for large networks. The netflow Python library accompanying this paper extends existing methods by preserving pore clusters that are a key characteristic of heterogeneous rocks. To this end dendrograms are extracted from experimental data and perturbed when generating larger networks. Moreover, the methods included in the netflow library are implemented in computationally efficient ways and enable the generation of large periodic networks that virtually eliminate boundary effects, which interfere in existing methods.

• The netflow Python library enables the generation of large irregular networks, as it preserves pore or node clusters which are present in certain natural rock types.

• The netflow Python library allows for the generation and flow analysis of boundary-free periodic networks. It further includes methods to convert periodic networks into conventional cubical ones.

Childbirth with epidural analgesia in a pregnant woman with hypokalemic periodic paralysis

Familial hypokalaemic periodic paralysis (FHPP) is an uncommon genetic disease characterized by muscle weakness associated with hypokalaemia. Episodes are precipitated by drugs, stress, metabolic diseases, hypothermia or infection. We report the case of a 38-year-old pregnant women with FHPP who underwent epidural analgesia for labour. Pregnant women with FHPP require multidisciplinary management involving an anaesthesiologist, a gynaecologist and a paediatrician. It is important to maintain normothermia, prevent hyperventilation, monitor electrolytes, avoid glucose infusions and medications that cause hypokalaemia, and administer potassium supplements when required. Locoregional techniques should be preferred over general anaesthesia. Early epidural analgesia reduces the risk of pain that could trigger an episode of FHPP. In the case of general anaesthesia, drugs that can cause malignant hyperthermia should be avoided, and short-acting non-depolarizing neuromuscular blockers with blockade-depth monitoring should be used.

Modeling transient particle transport in transient indoor airflow by fast fluid dynamics with the Markov chain method

It is crucial to accurately and efficiently predict transient particle transport in indoor environments to improve air distribution design and reduce health risks. For steady-state indoor airflow, fast fluid dynamics (FFD) + Markov chain model increased the calculation speed by around seven times compared to computational fluid dynamics (CFD) + Eulerian model and CFD + Lagrangian model, while achieving the same level of accuracy. However, the indoor airflow could be transient, if there were human behaviors involved like coughing or sneezing and air was supplied periodically. Therefore, this study developed an FFD + Markov chain model solver for predicting transient particle transport in transient indoor airflow. This investigation used two cases, transient particle transport in a ventilated two-zone chamber and a chamber with periodic air supplies, for validation. Case 1 had experimental data for validation and the results showed that the predicted particle concentration by FFD + Markov chain model matched well with the experimental data. Besides, it had similar accuracy as the CFD + Eulerian model. In the second case, the prediction by large eddy simulation (LES) was used for validating the FFD. The simulated particle concentrations by the Markov chain model and the Eulerian model were similar. The simulated particle concentrations by the Markov chain model and the Eulerian model were similar. The computational time of the FFD + Markov chain model was 7.8 times less than that of the CFD + Eulerian model.

Pediatric Migraine Phenomena and Variants: Don't Let Them Go Over Your Head

PURPOSE OF REVIEW

Primary care providers, general pediatric neurologists, and other related subspecialty providers require a clear understanding of pediatric migraine with typical aura and its variants.

RECENT FINDINGS

We highlight some of the genetic mutations known to contribute to specific types of migraine with aura, discuss the ophthalmologic phenomena of migraine and call attention to some of the earliest manifestations of migraine in children, many of which have correlates in adulthood. While the majority of headaches in children are migraine with or without aura or tension type, many migraine and aura variants exist. Early and accurate diagnosis of episodic syndromes associated with migraine, as defined by the 2018 ICHD-3 criteria, can help to reduce unnecessary imaging, referrals, cost and anxiety, thereby benefiting patients and their families.

A new clinical entity in T704M mutation in periodic paralysis

Periodic paralyses (PPs) are a group of rare disorders characterized by episodic, sudden-onset, flaccid paralysis of skeletal muscles usually resulting in complete recovery after the attacks. PPs are caused by abnormal, mostly potassium-sensitive excitability of the muscle tissue. Hypokalemic and hyperkalemic periodic paralysis (HypoKPP and HyperKPP) have been described according to their characteristic phenotypes and the serum potassium level during the attacks of weakness. The T704M mutation on the SCN4A gene is the most common mutation in HyperKPP. Different mutations of the SCN4A gene have also been reported in some cases of HypoKPP. In this study, a large Turkish family carrying the T704M mutation on the SCN4A gene with HypoKPP disease was examined. A similar history was noted in a total of 17 subjects in the pedigree. SCN4A gene of the patients was sequenced with Sanger sequencing. In this study, this mutation was associated with a HypoKKP diagnosis for the first time in the literature. The symptoms of hallucination and diplopia seen in patients had also never been indicated in the literature before. This report expands the phenotypic variability of the T704M mutation, further confirming the lack of genotype-phenotype correlation in SCN4A mutations.

Deepwater ocean outfalls: A sustainable solution for sewage discharge for mega-coastal cities (Sydney, Australia): Influence of deepwater ocean outfalls on shelf benthic infauna

In the early 1990s, a cliff-face disposal-system discharging approximately 940 ML/day, or 80% of sewage generated by the City of Sydney (Australia) (population 3.3 million) was replaced by three deepwater ocean outfalls. An 18-year benthic infauna monitoring study was undertaken to address earlier concerns of long-term accumulation from sewage discharges and potential adverse effects on the marine environment. Assessment of outfall community structure indicated organic input from discharges has not resulted in sediment anoxia. The current post-commissioning investigation detected a gradual change in community structure from north to south in the study area, which was also displayed in taxonomic turnover south of the Malabar outfall. Temporal fluctuation in community structure detected at the three outfall and three reference locations in the current study was also noted in the pre-commissioning study at these locations. Evidence provided by this study indicated the Sydney deepwater ocean outfalls do not cause significant ecological impact.

Periodic limb movements in sleep: Prevalence and associated sleepiness in the Wisconsin Sleep Cohort

OBJECTIVES

Periodic limb movements in sleep (PLMS) are thought to be prevalent in elderly populations, but their impact on quality of life remains unclear. We examined the prevalence of PLMS, impact of age on prevalence, and association between PLMS and sleepiness.

METHODS

We identified limb movements in 2335 Wisconsin Sleep Cohort polysomnograms collected over 12 years. Prevalence of periodic limb movement index (PLMI) ≥15 was calculated at baseline (n = 1084). McNemar's test assessed changes in prevalence over time. Association of sleepiness and PLMS evaluated using linear mixed modeling and generalized estimating equations. Models adjusted for confounders.

RESULTS

Prevalence of PLMI ≥15 at baseline was 25.3%. Longitudinal prevalence increased significantly with age (p = 2.97 × 10^-14). Sleepiness did not differ significantly between PLMI groups unless stratified by restless legs syndrome (RLS) symptoms. The RLS+/PLM+ group was sleepier than the RLS+/PLM- group. Multiple Sleep Latency Test trended towards increased alertness in the RLS-/PLM+ group compared to RLS-/PLM-.

CONCLUSIONS

A significant number of adults have PLMS and prevalence increased with age. No noteworthy association between PLMI category and sleepiness unless stratified by RLS symptoms.

SIGNIFICANCE

Our results indicate that RLS and PLMS may have distinct clinical consequences and interactions that can help guide treatment approach.

A DFT study of the structural and electronic properties of periodic forms of aniline and pyrrole polymers and aniline-pyrrole copolymer

The structural and electronic properties of polyaniline, polypyrrole, and poly(aniline-co-pyrrole) (Ani-co-Py) in periodic form were investigated using calculations based on density functional theory (DFT). One to three monomers of aniline and pyrrole were placed in a supercell, and the effects of dihedral angles between the monomers on the electronic properties of the polymers were explored. All polymer configurations were optimized, and the band structures and densities of states (DOSs) were calculated and compared. The band gap of each polymer was calculated as the smallest energy difference between the HOMO and LUMO bands. The results showed that both sets of homopolymers exhibit semiconducting behavior which becomes less prominent after copolymerization. A comparison of the band structures of the homopolymers and the copolymer indicated that the pyrrole in the copolymer acts as an acceptor. The projected density of states (PDOS) was examined to obtain additional insight into orbital interactions and to identify the atoms that are most influential in the electronic properties of the studied polymers.

Modelling leptospirosis in livestock

New Zealand has one of the highest (per capita) incidences of human leptospirosis in the world. It is the highest occurring occupational disease in New Zealand, often transmitted from livestock such as deer, sheep and cattle to humans. A cyclical model, showing the dynamics of infection of leptospirosis in farmed livestock in New Zealand, is presented. The limit cycle, bifurcation diagram and quasi-R₀ value of the system are determined. Leptospire death rate is used as a control parameter. Previously published parameter values are used in a case study to produce figures demonstrating analytical results. The model is used to predict conditions under which the infection will persist in the population.

Real-Time Closed Loop Diastolic Interval Control Prevents Cardiac Alternans in Isolated Whole Rabbit Hearts

Cardiac alternans, a beat-to-beat alternation in action potential duration (APD), can lead to fatal arrhythmias. During periodic pacing, changes in diastolic interval (DI) depend on subsequent changes in APD, thus enhancing cardiac instabilities through a 'feedback' mechanism. Recently, an anti-arrhythmic Constant DI pacing protocol was proposed and shown to be effective in suppressing alternans in 0D and 1D in silico studies. However, previous experimental validation of Constant DI pacing in the heart has been unsuccessful due to the spatio-temporal complexity of 2D cardiac tissue and the technical challenges in its real-time implementation. Here, we developed a novel closed loop system to detect T-waves from real-time ECG data, enabling successful implementation of Constant DI pacing protocol, and performed high-resolution optical mapping experiments on isolated whole rabbit hearts to validate its anti-arrhythmic effects. The results were compared with: (1) Periodic pacing (feedback inherent) and (2) pacing with heart rate variability (HRV) (feedback modulation) introduced by using either Gaussian or Physiological patterns. We observed that Constant DI pacing significantly suppressed alternans in the heart, while maintaining APD spatial dispersion and flattening the slope of the APD restitution curve, compared to traditional Periodic pacing. In addition, introduction of HRV in Periodic pacing failed to prevent cardiac alternans, and was arrhythmogenic.

A Case of Kleine-Levin Syndrome: Diagnostic and Therapeutic Challenge

Kleine-Levin syndrome (KLS) is a rare sleep disorder mainly affecting teenage boys in which the main features are intermittent hypersomnolence, behavioral and cognitive disturbances, hyperphagia, and in some cases hyper sexuality. Etiology is unknown, and there is no specific clinical or imaging test for this syndrome even though the illness has well-defined clinical features. Also, there is no effective treatment for KLS. KLS is self-limited, so the prognosis for these patients is not so bad. This study presents our case report and comprehensive workout that led to diagnosis which is primarily clinical. Our patient is a 20-year-old man referred to our clinic because of sleeping problems. At the age of 14, he presented with complaints of the excessive duration of sleep, increased appetite, excessive daytime sleepiness, loss of interest in social activities during attendance of high school and hallucinations. The excessive diagnostic procedure does not find pathological. Kleine-Levin syndrome (KLS) is a rare sleep disorder of unknown etiology which diagnosis is clinical and diagnostic workup is mainly to exclude other similar conditions. There is no specific therapy, but the disease is self-limited and with good prognosis.

Technical implications of new IUPAC elements in cheminformatics

The symbols for the new IUPAC elements named in November 2016 can introduce subtle ambiguities within cheminformatics software. The ambiguities are described and demonstrated by highlighting inconsistencies between software when handling existing element symbols.

Development and validation of effective real-time and periodic interinstrument comparison method for automatic hematology analyzers

OBJECTIVES

We developed and validated an interinstrument comparison method for automatic hematology analyzers based on the 99th percentile coefficient of variation (CV) cutoff of daily means and validated in both patient samples and quality control (QC) materials.

METHODS

A total of 120 patient samples were obtained over 6 months. Data from the first 3 months were used to determine 99th percentile CV cutoff values, and data obtained in the last 3 months were used to calculate acceptable ranges and rejection rates. Identical analyses were also performed using QC materials. Two instrument comparisons were also performed, and the most appropriate allowable total error (ATE) values were determined.

RESULTS

The rejection rates based on the 99th percentile cutoff values were within 10.00% and 9.30% for the patient samples and QC materials, respectively. The acceptable ranges of QC materials based on the currently used method were wider than those calculated from the 99th percentile CV cutoff values in most items. In two-instrument comparisons, 34.8% of all comparisons failed, and 87.0% of failed comparisons were successful when 4 SD was applied as an ATE value instead of 3 SD.

CONCLUSIONS

The 99th percentile CV cutoff value-derived daily acceptable ranges can be used as a real-time interinstrument comparison method in both patient samples and QC materials. Applying 4 SD as an ATE value can significantly reduce unnecessarily followed recalibration in the leukocyte differential counts, reticulocytes, and mean corpuscular volume.

Partial cross-enhancement in models for dengue epidemiology

Four distinct serotypes of dengue virus co-circulate in many parts of the world. Antibodies to one serotype prevent infection with the homologous serotype, but may enhance infections with heterologous serotypes. Enhanced secondary infections have been implicated in the majority of severe cases, termed dengue hemorrhagic fever. Conventionally, mathematical models assume that all heterologous secondary infections are subject to enhanced susceptibility or transmissibility. However, empirical data show that only a minority of secondary infections lead to severe disease, which suggests that only a minority of secondary infections are subject to enhancement. We present a new modelling framework in which the population susceptible to secondary infection is split into a group prone to enhanced infection and a group with some degree of cross-protection. We use this framework to re-evaluate the role of enhanced infections in several well known dengue models that exhibit multi-annual epidemiological oscillations. We show that enhancement is unlikely to be driving such oscillations but may be modifying the effects of other drivers.