Chronic Cannabis users exhibit altered oscillatory dynamics and functional connectivity serving visuospatial processing.

BACKGROUND: Cannabis is the most widely used psychoactive drug in the United States. While multiple studies have associated acute cannabis consumption with alterations in cognitive function (e.g., visual and spatial attention), far less is known regarding the effects of chronic consumption on the neural dynamics supporting these cognitive functions. METHODS: We used magnetoencephalography (MEG) and an established visuospatial processing task to elicit multi-spectral neuronal responses in 44 regular cannabis users and 53 demographically matched non-user controls. To examine the effects of chronic cannabis use on the oscillatory dynamics underlying visuospatial processing, neural responses were imaged using a time-frequency resolved beamformer and compared across groups. RESULTS: Neuronal oscillations serving visuospatial processing were identified in the theta (4-8 Hz), alpha (8-14 Hz), and gamma range (56-76 Hz), and these were imaged and examined for group differences. Our key results indicated that users exhibited weaker theta oscillations in occipital and cerebellar regions and weaker gamma responses in the left temporal cortices compared to non-users. Lastly, alpha oscillations did not differ, but alpha connectivity among higher-order attention areas was weaker in cannabis users relative to non-users and correlated with performance. CONCLUSIONS: Overall, these results suggest that chronic cannabis users have alterations in the oscillatory dynamics and neural connectivity serving visuospatial attention. Such alterations were observed across multiple cortical areas critical for higher-order processing and may reflect compensatory activity and/or the initial emergence of aberrant dynamics. Future work is needed to fully understand the implications of altered multispectral oscillations and neural connectivity in cannabis users.

Regular cannabis use modulates gamma activity in brain regions serving motor control.

BACKGROUND: People who regularly use cannabis exhibit altered brain dynamics during cognitive control tasks, though the impact of regular cannabis use on the neural dynamics serving motor control remains less understood. AIMS: We sought to investigate how regular cannabis use modulates the neural dynamics serving motor control. METHODS: Thirty-four people who regularly use cannabis (cannabis+) and 33 nonusers (cannabis-) underwent structured interviews about their substance use history and performed the Eriksen flanker task to map the neural dynamics serving motor control during high-density magnetoencephalography (MEG). The resulting neural data were transformed into the time-frequency domain to examine oscillatory activity and were imaged using a beamforming approach. RESULTS: MEG sensor-level analyses revealed robust beta (16-24 Hz) and gamma oscillations (66-74 Hz) during motor planning and execution, which were imaged using a beamformer. Both responses peaked in the left primary motor cortex and voxel time series were extracted to evaluate the spontaneous and oscillatory dynamics. Our key findings indicated that the cannabis+ group exhibited weaker spontaneous gamma activity in the left primary motor cortex relative to the cannabis- group, which scaled with cannabis use and behavioral metrics. Interestingly, regular cannabis use was not associated with differences in oscillatory beta and gamma activity, and there were no group differences in spontaneous beta activity. CONCLUSIONS: Our findings suggest that regular cannabis use is associated with suppressed spontaneous gamma activity in the left primary motor cortex, which scales with the degree of cannabis use disorder symptomatology and is coupled to behavioral task performance.

High-definition transcranial direct current stimulation of the parietal cortices modulates the neural dynamics underlying verbal working memory.

Verbal working memory (vWM) is an essential limited-capacity cognitive system that spans the fronto-parietal network and utilizes the subprocesses of encoding, maintenance, and retrieval. With the recent widespread use of noninvasive brain stimulation techniques, multiple recent studies have examined whether such stimulation may enhance cognitive abilities such as vWM, but the findings to date remain unclear in terms of both behavior and critical brain regions. In the current study, we applied high-definition direct current stimulation to the left and right parietal cortices of 39 healthy adults in three separate sessions (left anodal, right anodal, and sham). Following stimulation, participants completed a vWM task during high-density magnetoencephalography (MEG). Significant neural responses at the sensor-level were imaged using a beamformer and whole-brain ANOVAs were used to identify the specific neuromodulatory effects of the stimulation conditions on neural responses serving distinct phases of vWM. We found that right stimulation had a faciliatory effect relative to left stimulation and sham on theta oscillations during encoding in the right inferior frontal, while the opposite pattern was observed for left supramarginal regions. Stimulation also had a faciliatory effect on theta in occipital regions and alpha in temporal regions regardless of the laterality of stimulation. In summary, our data suggest that parietal HD-tDCS both facilitates and interferes with neural responses underlying both the encoding and maintenance phases of vWM. Future studies are warranted to determine whether specific tDCS parameters can be tuned to accentuate the facilitation responses and attenuate the interfering aspects.

Optimal gamma-band entrainment of visual cortex.

Visual entrainment is a powerful and widely used research tool to study visual information processing in the brain. While many entrainment studies have focused on frequencies around 14-16 Hz, there is renewed interest in understanding visual entrainment at higher frequencies (e.g., gamma-band entrainment). Notably, recent groundbreaking studies have demonstrated that gamma-band visual entrainment at 40 Hz may have therapeutic effects in the context of Alzheimer's disease (AD) by stimulating specific neural ensembles, which utilize GABAergic signaling. Despite such promising findings, few studies have investigated the optimal parameters for gamma-band visual entrainment. Herein, we examined whether visual stimulation at 32, 40, or 48 Hz produces optimal visual entrainment responses using high-density magnetoencephalography (MEG). Our results indicated strong entrainment responses localizing to the primary visual cortex in each condition. Entrainment responses were stronger for 32 and 40 Hz relative to 48 Hz, indicating more robust synchronization of neural ensembles at these lower gamma-band frequencies. In addition, 32 and 40 Hz entrainment responses showed typical patterns of habituation across trials, but this effect was absent for 48 Hz. Finally, connectivity between visual cortex and parietal and prefrontal cortices tended to be strongest for 40 relative to 32 and 48 Hz entrainment. These results suggest that neural ensembles in the visual cortex may resonate at around 32 and 40 Hz and thus entrain more readily to photic stimulation at these frequencies. Emerging AD therapies, which have focused on 40 Hz entrainment to date, may be more effective at lower relative to higher gamma frequencies, although additional work in clinical populations is needed to confirm these findings. PRACTITIONER POINTS: Gamma-band visual entrainment has emerged as a therapeutic approach for eliminating amyloid in Alzheimer's disease, but its optimal parameters are unknown. We found stronger entrainment at 32 and 40 Hz compared to 48 Hz, suggesting neural ensembles prefer to resonate around these relatively lower gamma-band frequencies. These findings may inform the development and refinement of innovative AD therapies and the study of GABAergic visual cortical functions.

Chronic cannabis use alters the spontaneous and oscillatory gamma dynamics serving cognitive control.

Regular cannabis use is associated with cortex-wide changes in spontaneous and oscillatory activity, although the functional significance of such changes remains unclear. We hypothesized that regular cannabis use would suppress spontaneous gamma activity in regions serving cognitive control and scale with task performance. Participants (34 cannabis users, 33 nonusers) underwent an interview regarding their substance use history and completed the Eriksen flanker task during magnetoencephalography (MEG). MEG data were imaged in the time-frequency domain and virtual sensors were extracted from the peak voxels of the grand-averaged oscillatory interference maps to quantify spontaneous gamma activity during the pre-stimulus baseline period. We then assessed group-level differences in spontaneous and oscillatory gamma activity, and their relationship with task performance and cannabis use metrics. Both groups exhibited a significant behavioral flanker interference effect, with slower responses during incongruent relative to congruent trials. Mixed-model ANOVAs indicated significant gamma-frequency neural interference effects in the left frontal eye fields (FEF) and left temporoparietal junction (TPJ). Further, a group-by-condition interaction was detected in the left FEF, with nonusers exhibiting stronger gamma oscillations during incongruent relative to congruent trials and cannabis users showing no difference. In addition, spontaneous gamma activity was sharply suppressed in cannabis users relative to nonusers in the left FEF and TPJ. Finally, spontaneous gamma activity in the left FEF and TPJ was associated with task performance across all participants, and greater cannabis use was associated with weaker spontaneous gamma activity in the left TPJ of the cannabis users. Regular cannabis use was associated with weaker spontaneous gamma in the TPJ and FEF. Further, the degree of use may be proportionally related to the degree of suppression in spontaneous activity in the left TPJ.

Neuromodulatory effects of parietal high-definition transcranial direct-current stimulation on network-level activity serving fluid intelligence.

Fluid intelligence (Gf) involves rational thinking skills and requires the integration of information from different cortical regions to resolve novel complex problems. The effects of non-invasive brain stimulation on Gf have been studied in attempts to improve Gf, but such studies are rare and the few existing have reached conflicting conclusions. The parieto-frontal integration theory of intelligence (P-FIT) postulates that the parietal and frontal lobes play a critical role in Gf. To investigate the suggested role of parietal cortices, we applied high-definition transcranial direct current stimulation (HD-tDCS) to the left and right parietal cortices of 39 healthy adults (age 19-33 years) for 20 min in three separate sessions (left active, right active and sham). After completing the stimulation session, the participants completed a logical reasoning task based on Raven's Progressive Matrices during magnetoencephalography. Significant neural responses at the sensor level across all stimulation conditions were imaged using a beamformer. Whole-brain, spectrally constrained functional connectivity was then computed to examine the network-level activity. Behaviourally, we found that participants were significantly more accurate following left compared to right parietal stimulation. Regarding neural findings, we found significant HD-tDCS montage-related effects in brain networks thought to be critical for P-FIT, including parieto-occipital, fronto-occipital, fronto-parietal and occipito-cerebellar connectivity during task performance. In conclusion, our findings showed that left parietal stimulation improved abstract reasoning abilities relative to right parietal stimulation and support both P-FIT and the neural efficiency hypothesis. KEY POINTS: Abstract reasoning is a critical component of fluid intelligence and is known to be served by multispectral oscillatory activity in the fronto-parietal cortices. Recent studies have aimed to improve abstract reasoning abilities and fluid intelligence overall through behavioural training, but the results have been mixed. High-definition transcranial direct-current stimulation (HD-tDCS) applied to the parietal cortices modulated task performance and neural oscillations during abstract reasoning. Left parietal stimulation resulted in increased accuracy and decreased functional connectivity between occipital regions and frontal, parietal, and cerebellar regions. Future studies should investigate whether HD-tDCS alters abstract reasoning abilities in those who exhibit declines in performance, such as healthy ageing populations.

Conservation energetics of beluga whales: using resting and swimming metabolism to understand threats to an endangered population.

The balance between energetic costs and acquisition in free-ranging species is essential for survival, and provides important insights regarding the physiological impact of anthropogenic disturbances on wild animals. For marine mammals such as beluga whales (Delphinapterus leucas), the first step in modeling this bioenergetic balance requires an examination of resting and active metabolic demands. Here, we used open-flow respirometry to measure oxygen consumption during surface rest and submerged swimming by trained beluga whales, and compared these measurements with those of a commonly studied odontocete, the Atlantic bottlenose dolphin (Tursiops truncatus). Both resting metabolic rate (3012±126.0 kJ h-1) and total cost of transport (1.4±0.1 J kg-1 m-1) of beluga whales were consistent with predicted values for moderately sized marine mammals in temperate to cold-water environments, including dolphins measured in the present study. By coupling the rate of oxygen consumption during submerged swimming with locomotor metrics from animal-borne accelerometer tags, we developed predictive relationships for assessing energetic costs from swim speed, stroke rate and partial dynamic acceleration. Combining these energetic data with calculated aerobic dive limits for beluga whales (8.8 min), we found that high-speed responses to disturbance markedly reduce the whale's capacity for prolonged submergence, pushing the cetaceans to costly anaerobic performances that require prolonged recovery periods. Together, these species-specific energetic measurements for beluga whales provide two important metrics, gait-related locomotor costs and aerobic capacity limits, for identifying relative levels of physiological vulnerability to anthropogenic disturbances that have become increasingly pervasive in their Arctic habitats.

Ad libitum dehydration is associated with poorer performance on a sustained attention task but not other measures of cognitive performance among middle-to-older aged community-dwelling adults: A short-term longitudinal study.

OBJECTIVE: Hydration status and water intake are critical to physiological health. Despite a popular narrative that dehydration impairs cognitive performance, results are mixed in the literature. Therefore, we tested how hydration status was associated with cognitive performance in an ad libitum state over the course of 3 months. METHODS: Data come from a short-term longitudinal study among middle-to-older aged US adults (n = 78) measured three times (207 observations). All participants were scheduled for 8:00 a.m. visits for the baseline, two-week, and 3-month examinations where they completed surveys, neuropsychological tests to measure cognitive performance, anthropometrics, and a blood draw for biomarker analysis. Serum osmolality (Sosm) was measured as a biomarker of hydration status using osmometry. Four cognitive performance tasks were assessed, including inhibition, working memory, cognitive flexibility, and sustained attention. RESULTS: Panel random effects linear regressions demonstrate that there was an inverse association between dehydration and sustained attention, whereas there were no significant relationships between dehydration and inhibition, working memory, and cognitive flexibility. Adults who were dehydrated (defined as Sosm >300 mOsm/kg) performed substantially worse (B = 0.65 z-score; SE = 0.28; p = .020) on the sustained attention task than those who were not dehydrated adjusting for time fixed effects, age, body mass index, sex, and educational attainment. CONCLUSION: This short-term longitudinal study found that dehydration was only associated with poorer performance on a cognitive performance task that required sustained attention. Maintaining adequate hydration may be increasingly important for middle-to-older aged adults to ensure proper cognitive function, particularly as water needs increase in future climatic scenarios.

The neural oscillations serving task switching are altered in cannabis users.

BACKGROUND: Regular cannabis is known to impact higher-order cognitive processes such as attention, but far less is known regarding cognitive flexibility, a component of executive function. Moreover, whether such changes are related to aberrations in the neural oscillatory dynamics serving flexibility remains poorly understood. AIMS: Quantify the neural oscillatory dynamics serving cognitive flexibility by having participants complete a task-switching paradigm during magnetoencephalography (MEG). Probe whole-brain maps to identify alterations in chronic cannabis users relative to nonusers and determine how these alterations relate to the degree of cannabis use involvement. METHODS: In all, 25 chronic cannabis users and 30 demographically matched nonuser controls completed neuropsychological testing, an interview regarding their substance use, a urinalysis, and a task switch paradigm during MEG. Time-frequency windows of interest were identified using a data-driven statistical approach and these were imaged using a beamformer. Whole-brain neural switch cost maps were computed by subtracting the oscillatory maps of the no-switch condition from the switch condition per participant. These were examined for group differences. RESULTS: Cannabis users had weaker theta switch cost responses in the dorsolateral and dorsomedial prefrontal cortices, while nonusers showed the typical pattern of greater recruitment during switch relative to no switch trials. In addition, theta activity in the dorsomedial prefrontal cortex was significantly correlated with cannabis use involvement. CONCLUSIONS: Cannabis users exhibited altered theta switch cost activity compared to nonusers in prefrontal cortical regions, which are critical for cognitive flexibility. This activity scaled with cannabis use involvement, indicating a link between cannabis use and aberrant oscillatory activity underlying cognitive flexibility.

Regular cannabis use alters the neural dynamics serving complex motor control.

Cannabis is the most widely used recreational drug in the United States and regular use has been linked to deficits in attention and memory. However, the effects of regular use on motor control are less understood, with some studies showing deficits and others indicating normal performance. Eighteen users and 23 nonusers performed a motor sequencing task during high-density magnetoencephalography (MEG). The MEG data was transformed into the time-frequency domain and beta responses (16-24 Hz) during motor planning and execution phases were imaged separately using a beamformer approach. Whole-brain maps were examined for group (cannabis user/nonuser) and time window (planning/execution) effects. As expected, there were no group differences in task performance (e.g., reaction time, accuracy, etc.). Regular cannabis users exhibited stronger beta oscillations in the contralateral primary motor cortex compared to nonusers during the execution phase of the motor sequences, but not during the motor planning phase. Similar group-by-time window interactions were observed in the left superior parietal, right inferior frontal cortices, right posterior insular cortex, and the bilateral motor cortex. We observed differences in the neural dynamics serving motor control in regular cannabis users compared to nonusers, suggesting regular users may employ compensatory processing in both primary motor and higher-order motor cortices to maintain adequate task performance. Future studies will need to examine more complex motor control tasks to ascertain whether this putative compensatory activity eventually becomes exhausted and behavioral differences emerge.

Quality of Pancreatic Cyst Clinical Practice Guidelines.

BACKGROUND: There are various published clinical practice guidelines (CPGs) for the management of pancreatic cystic lesions. However, the quality of these guidelines has not been systematically appraised. This study aimed to evaluate the quality of CPGs published in the last 5 years for the management of pancreatic cysts. METHODS: A systematic search of the PubMed database for eligible CPGs published between January 1, 2016 and November 17, 2021, using a sensitive filter. The quality of the CPGs was independently evaluated using the Appraisal of Guidelines for Research & Evaluation II instrument, with domain scores considered sufficient quality if >60% and good quality if >80%. RESULTS: The search yielded 4 eligible CPGs out of 426 citations. The scores varied for different domains for each CPG, with the overall median score being 79% for scope and purpose, 26% for stakeholder involvement, 51% for rigor of development, 69% for clarity of presentation, 14% for applicability, and 75% for editorial independence. CONCLUSIONS: The study revealed that the quality of the CPGs for pancreatic cyst management in adults remains moderate at best. Patient representatives were not involved in any of the CPG development process. There is a significant scope for improvement in methodological rigor and clarity of presentation.

Elevated CRP and TNF-α levels are associated with blunted neural oscillations serving fluid intelligence.

INTRODUCTION: Inflammatory processes help protect the body from potential threats such as bacterial or viral invasions. However, when such inflammatory processes become chronically engaged, synaptic impairments and neuronal cell death may occur. In particular, persistently high levels of C-reactive protein (CRP) and tumor necrosis factor-alpha (TNF-α) have been linked to deficits in cognition and several psychiatric disorders. Higher-order cognitive processes such as fluid intelligence (Gf) are thought to be particularly vulnerable to persistent inflammation. Herein, we investigated the relationship between elevated CRP and TNF-α and the neural oscillatory dynamics serving Gf. METHODS: Seventy adults between the ages of 20-66 years (Mean = 45.17 years, SD = 16.29, 21.4% female) completed an abstract reasoning task that probes Gf during magnetoencephalography (MEG) and provided a blood sample for inflammatory marker analysis. MEG data were imaged in the time-frequency domain, and whole-brain regressions were conducted using each individual's plasma CRP and TNF-α concentrations per oscillatory response, controlling for age, BMI, and education. RESULTS: CRP and TNF-α levels were significantly associated with region-specific neural oscillatory responses. In particular, elevated CRP concentrations were associated with altered gamma activity in the right inferior frontal gyrus and right cerebellum. In contrast, elevated TNF-α levels scaled with alpha/beta oscillations in the left anterior cingulate and left middle temporal, and gamma activity in the left intraparietal sulcus. DISCUSSION: Elevated inflammatory markers such as CRP and TNF-α were associated with aberrant neural oscillations in regions important for Gf. Linking inflammatory markers with regional neural oscillations may hold promise in identifying mechanisms of cognitive and psychiatric disorders.

Gender Disparity in Academic Gastroenterology: Beginning of the End of the Underrepresentation of Women?

BACKGROUND: Though there are an increasing number of female medical graduates, women remain underrepresented in academic medicine. There have been several reasons to explain this gender disparity, including marital status, number of children, number of hours worked, job flexibility, perceptions of women as inferior leaders, gender bias, sexual harassment, and unsupportive academic climates. AIMS: This study aimed to investigate the relationship between scholarly productivity and the representation of female gastroenterologists in academia. Specifically, scholarly productivity measured by the h-index and academic rank were explored to determine if there were gender disparities in academic productivity and rank in gastroenterology. METHODS: Gastroenterology departmental listings were obtained from the Fellowship and Residency Interactive Database of the American Medical Association. The Scopus database was used to record each physician's h-index. Statistical analyses were conducted with Wilcoxon rank-sum test, which compared matched samples by academic rank, and ANOVA tests, which compared multiple academic ranks. RESULTS: Out of 1703 academic gastroenterologists, women account for 25% of academic physicians. Women have statistically lower h-indices at the level of Assistant Professor (p = 0.0012), and at the level of Chair (p = 0.01). There was no difference in h-indices between male and female at the rank of Associate Professor and Professor. CONCLUSIONS: While these results mirror patterns appreciated in other fields of medicine, the results at the rank of Chair may suggest that despite the lower h-index compared to their male counterparts, females are perceived as having strong inherent leadership skills outside of academic productivity that are also conducive to leading a department and may be contributing to their rise to Chair.

Variation in urine osmolality throughout pregnancy: a longitudinal, randomized-control trial among women with overweight and obesity.

PURPOSE: Water needs increase during pregnancy, and proper hydration is critical for maternal and fetal health. This study characterized weekly hydration status changes throughout pregnancy and examined change in response to a randomized, behavioral intervention. An exploratory analysis tested how underhydration during pregnancy was associated with birth outcomes. METHODS: The Healthy Mom Zone Study is a longitudinal, randomized-control trial intervention aiming to regulate gestational weight gain (GWG) in pregnant women with overweight/obesity (n = 27). Fourteen women received standard of care; 13 women additionally received weekly guidance on nutrition, physical activity, water intake, and health-promoting behaviors. Hydration status was measured weekly via overnight urine osmolality (Uosm) from ~ 8-36 weeks gestation; underhydration was dichotomized (Uosm ≥ 500 mOsm/kg). Gestational age- and sex-standardized birth weight and length z scores and percentiles were calculated. We used mixed-effect and linear regression models to test covariate-adjusted relationships. RESULTS: No differences existed in Uosm or other characteristics between control and intervention women at baseline. Significant interactions (p = 0.01) between intervention and week of pregnancy on Uosm indicated intervention women maintained lower Uosm, whereas control women had a significant quadratic (inverse-U) relationship and greater Uosm in the second and early third trimesters. Results were consistent across robustness and sensitivity checks. Exploratory analyses suggest underhydration was associated with birth weight, but not length, in opposite ways in the second vs. third trimester. CONCLUSION: A multi-component behavioral intervention helped women with overweight/obesity maintain better hydration throughout pregnancy. Future studies should confirm birth outcome results as they have important implications for early life nutrition. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03945266; registered May 10, 2019 retrospectively.

Metabolic trade-offs in tropical and subtropical marine mammals: unique maintenance and locomotion costs in West Indian manatees and Hawaiian monk seals.

Unlike the majority of marine mammal species, Hawaiian monk seals (Neomonachus schauinslandi) and West Indian manatees (Trichechus manatus latirostris) reside exclusively in tropical or subtropical waters. Although potentially providing an energetic benefit through reduced maintenance and thermal costs, little is known about the cascading effects that may alter energy expenditure during activity, dive responses and overall energy budgets for these warm-water species. To examine this, we used open-flow respirometry to measure the energy expended during resting and swimming in both species. We found that the average resting metabolic rates (RMRs) for both the adult monk seal (753.8±26.1 kJ h-1, mean±s.e.m.) and manatees (887.7±19.5 kJ h-1) were lower than predicted for cold-water marine mammal species of similar body mass. Despite these relatively low RMRs, both total cost per stroke and total cost of transport (COTTOT) during submerged swimming were similar to predictions for comparably sized marine mammals (adult monk seal: cost per stroke=5.0±0.2 J kg-1 stroke-1, COTTOT=1.7±0.1 J kg-1 m-1; manatees: cost per stroke=2.0±0.4 J kg-1 stroke-1, COTTOT=0.87±0.17 J kg-1 m-1). These lower maintenance costs result in less variability in adjustable metabolic costs that occur during submergence for warm-water species. However, these reduced maintenance costs do not appear to confer an advantage in overall energetic costs during activity, potentially limiting the capacity of warm-water species to respond to anthropogenic or environmental threats that require increased energy expenditure.

Hepatitis-Induced Porphyria: Are Direct-Acting Antiviral Agents the Way of the Future?

Porphyria cutanea tarda (PCT) is the most common porphyria and has a strong association with hepatitis C virus (HCV) infection and iron overload. Previous HCV treatment regimens, including interferon with or without ribavirin, may precipitate PCT relapse. Few case reports have shown that newer oral therapies, such as direct-acting antiviral agents, can successfully treat PCT parallel with HCV treatment. We present a case of a patient with non-iron-associated mixed porphyria that dramatically improved with direct-acting antiviral agent therapy for his HCV supporting the association of porphyria with chronic HCV.

Variation in mineral element composition of landrace taro (Colocasia esculenta) corms grown under dryland farming system in South Africa.

Taro [Colocasia esculenta (L.) Schott] has the potential to address food and nutrition insecurity in sub-Saharan Africa. However, the nutrient content of taro is yet to be fully elucidated. The objective of this study was to evaluate mineral element content as a proxy for nutritional value of different taro genotypes. The study evaluated 14 taro accessions at Roodeplaat and Umbumbulu in South Africa based on their calcium (Ca), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorous (P) and zinc (Zn) content. The accessions were planted in a randomized complete block design, replicated three times under field conditions. The mineral element content varied significantly (p < 0.05) among the genotypes. Genotypes Amad7-2, Umbu8 and Amad101 exhibited high Ca (≥432 mg kg-1), Fe (≥32 mg kg-1) and Mg (≥229 mg kg-1) across the locations. The first principal component (PC) accounted for 33.7% of the variation and was strongly associated with Zn (r = 0.94, p < 0.001) and P (r = 0.89, p < 0.001). The second PC explained 29.7% of the variation and was associated with Na (r = 0.83, p < 0.001), Mg (r = 0.76, p < 0.001) and K (r = 0.55, p < 0.05). Fe and Mn contributed below the 12.5% threshold to the PCs and were considered as less discriminatory among the accessions. The negative correlations among some of the mineral elements would be a challenge for selection and breeding of nutritious taro accessions. This information is essential to select superior local accessions based on their mineral element content for developing breeding populations and lines for improving nutrition quality among poor households in sub-Saharan Africa.

Cervical air sac oxygen profiles in diving emperor penguins: parabronchial ventilation and the respiratory oxygen store.

Some marine birds and mammals can perform dives of extraordinary duration and depth. Such dive performance is dependent on many factors, including total body oxygen (O2) stores. For diving penguins, the respiratory system (air sacs and lungs) constitutes 30-50% of the total body O2 store. To better understand the role and mechanism of parabronchial ventilation and O2 utilization in penguins both on the surface and during the dive, we examined air sac partial pressures of O2 (PO2 ) in emperor penguins (Aptenodytes forsteri) equipped with backpack PO2  recorders. Cervical air sac PO2  values at rest were lower than in other birds, while the cervical air sac to posterior thoracic air sac PO2  difference was larger. Pre-dive cervical air sac PO2  values were often greater than those at rest, but had a wide range and were not significantly different from those at rest. The maximum respiratory O2 store and total body O2 stores calculated with representative anterior and posterior air sac PO2  data did not differ from prior estimates. The mean calculated anterior air sac O2 depletion rate for dives up to 11 min was approximately one-tenth that of the posterior air sacs. Low cervical air sac PO2  values at rest may be secondary to a low ratio of parabronchial ventilation to parabronchial blood O2 extraction. During dives, overlap of simultaneously recorded cervical and posterior thoracic air sac PO2  profiles supported the concept of maintenance of parabronchial ventilation during a dive by air movement through the lungs.

Identification of potential SARS-CoV-2 inhibitors from South African medicinal plant extracts using molecular modelling approaches.

The coronavirus is a group of viruses found in animals as well as humans and have been detected since the 1960s. However, a newly identified form, SARS-CoV-2, has triggered a recent pandemic of respiratory disease now called COVID-19. There is currently no specific antiviral drug for the treatment of this pandemic, with most treatment strategies focused on symptomatic management and supportive therapy. As such, several drug discovery efforts are ongoing for potent treatment agents, with medicinal plants gradually gaining prominence. Approximately 80% of the South African population use traditional medicines to meet their primary health care needs. The current study aimed to identify potential COVID-19 therapeutic agents from a list of 29 bioactive compounds isolated from commonly used South African medicinal plants using molecular docking and molecular dynamics. Molecular docking identified arabic acid from Acacia senegal and L-canavanine found in Sutherlandia frutescens as a potential inhibitor of SARS-CoV-2 3C-like main protease. Similarly, hypoxoside isolated from Hypoxis hemerocallidea and uzarin from Xysmalobium undulatum, were identified as a potential inhibitor of SARS-CoV-2 receptor binding domain and SARS-CoV-2 RNA-dependent polymerase. These four bioactive compounds exhibited favourable binding orientations characterized by strong molecular interactions within respective inhibitors binding pockets of the target enzymes. Molecular dynamics simulations revealed that the binding of the identified inhibitors are characterized by structural perturbations which favour the inhibitory potency of these bioactive compounds. Additionally, in silico pharmacokinetic assessment of the compounds demonstrated favourable anti-SARS-CoV-2 properties. Although not conclusive, further experimental exploration of these compounds could serve as a starting point for the discovery of novel SARS-CoV-2 therapeutic.

First Reported Use of Highly Adsorptive Hemofilter in Critically Ill COVID-19 Patients in the USA.

Critically ill patients with coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) develop respiratory failure and septic shock. Extracorporeal blood purification is proposed as an adjuvant therapy for sepsis and aims at controlling the dysregulated autoimmune system. We describe our experience in treating COVID-19 patients with the oXiris® hemofilter which adsorbs both cytokines and endotoxins, provides renal replacement therapy and has anti-thrombogenic properties. It was approved by the US Food and Drug Administration (FDA) under emergency use authorization for COVID-19 patients in April 2020. In our study, the use of the oXiris® filter decreased levels of inflammatory markers including interleukin-6 (IL-6), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), and improved clinical outcomes in two out of three patients.