Not just range limits: Warming rate and thermal sensitivity shape climate change vulnerability in a species range center

Climate change manifests unevenly across space and time and produces complex patterns of stress for ecological systems. Species can also show substantial among-population variability in response to environmental change across their geographic range due to evolutionary processes. Explanatory factors or their proxies, such as temperature and latitude, help parse these sources of environmental and intraspecific variability; however, overemphasizing latitudinal trends can obscure the role of local environmental conditions in shaping population vulnerability to climate change. Focusing on the geographic center of a species range to disentangle latitude, we test the hypothesis that populations from warmer regions of a species range are more vulnerable to ocean warming. We conducted a mesocosm experiment and field reciprocal transplant with four populations of a marine snail, Nucella lamellosa, from two regions in British Columbia, Canada, that differ in thermal characteristics: the Central Coast, a cool region, and the Strait of Georgia, one of the warmest regions of this species' range and one that is warming faster than the Central Coast. Populations from the Strait of Georgia experienced growth reductions at contemporary summertime seawater temperatures in the laboratory and showed stark reductions in survival and growth under future seawater conditions and when outplanted at their native transplant sites. This indicates a high vulnerability to ocean warming, especially given the faster rate of ocean warming in this region. In contrast, populations from the cooler Central Coast demonstrated high performance at contemporary seawater temperatures and high growth and survival in projected future seawater temperatures and at their native outplant sites. Given their position within the geographic center of N. lamellosa's range, extirpation events in the vulnerable Strait of Georgia populations could compromise connectivity within the metapopulation and lead to gaps across this species' range. Overall, our study supports predictions that populations from warm regions of species ranges are more vulnerable to environmental warming, suggests that the Strait of Georgia and other inland or coastal seas could be focal points for climate change effects and ecological transformation, and emphasizes the importance of analyzing climate change vulnerability in the context of regional environmental data and throughout a species' range.

Characterization of cannabinoid plasma concentration, maternal health, and cytokine levels in a rat model of prenatal Cannabis smoke exposure

Cannabis sativa has gained popularity as a "natural substance", leading many to falsely assume that it is not harmful. This assumption has been documented amongst pregnant mothers, many of whom consider Cannabis use during pregnancy as benign. The purpose of this study was to validate a Cannabis smoke exposure model in pregnant rats by determining the plasma levels of cannabinoids and associated metabolites in the dams after exposure to either Cannabis smoke or injected cannabinoids. Maternal and fetal cytokine and chemokine profiles were also assessed after exposure. Pregnant Sprague-Dawley rats were treated daily from gestational day 6-20 with either room air, i.p. vehicle, inhaled high-Δ9-tetrahydrocannabinol (THC) (18% THC, 0.1% cannabidiol [CBD]) smoke, inhaled high-CBD (0.7% THC, 13% CBD) smoke, 3 mg/kg i.p. THC, or 10 mg/kg i.p. CBD. Our data reveal that THC and CBD, but not their metabolites, accumulate in maternal plasma after repeated exposures. Injection of THC or CBD was associated with fewer offspring and increased uterine reabsorption events. For cytokines and chemokines, injection of THC or CBD up-regulated several pro-inflammatory cytokines compared to control or high-THC smoke or high-CBD smoke in placental and fetal brain tissue, whereas smoke exposure was generally associated with reduced cytokine and chemokine concentrations in placental and fetal brain tissue compared to controls. These results support existing, but limited, knowledge on how different routes of administration contribute to inconsistent manifestations of cannabinoid-mediated effects on pregnancy. Smoked Cannabis is still the most common means of human consumption, and more preclinical investigation is needed to determine the effects of smoke inhalation on developmental and behavioural trajectories.

Manufacturing of quantum-tunneling MIM nanodiodes via rapid atmospheric CVD in terahertz band

Quantum-tunneling metal-insulator-metal (MIM) diodes have emerged as a significant area of study in the field of materials science and electronics. Our previous work demonstrated the successful fabrication of these diodes using atmospheric pressure chemical vapor deposition (AP-CVD), a scalable method that surpasses traditional vacuum-based methods and allows for the fabrication of high-quality Al2O3 films with few pinholes. Here, we show that despite their extremely small size 0.002 µm2, the MIM nanodiodes demonstrate low resistance at zero bias. Moreover, we have observed a significant enhancement in resistance by six orders of magnitude compared to our prior work, Additionally, we have achieved a high responsivity of 9 AW-1, along with a theoretical terahertz cut-off frequency of 0.36 THz. Our approach provides an efficient alternative to cleanroom fabrication, opening up new opportunities for manufacturing terahertz-Band devices. The results of our study highlight the practicality and potential of our method in advancing nanoelectronics. This lays the foundation for the development of advanced quantum devices that operate at terahertz frequencies, with potential applications in telecommunications, medical imaging, and security systems.

Scaling of an antibody validation procedure enables quantification of antibody performance in major research applications

Antibodies are critical reagents to detect and characterize proteins. It is commonly understood that many commercial antibodies do not recognize their intended targets, but information on the scope of the problem remains largely anecdotal, and as such, feasibility of the goal of at least one potent and specific antibody targeting each protein in a proteome cannot be assessed. Focusing on antibodies for human proteins, we have scaled a standardized characterization approach using parental and knockout cell lines (Laflamme et al., 2019) to assess the performance of 614 commercial antibodies for 65 neuroscience-related proteins. Side-by-side comparisons of all antibodies against each target, obtained from multiple commercial partners, have demonstrated that: (i) more than 50% of all antibodies failed in one or more applications, (ii) yet, ~50-75% of the protein set was covered by at least one high-performing antibody, depending on application, suggesting that coverage of human proteins by commercial antibodies is significant; and (iii) recombinant antibodies performed better than monoclonal or polyclonal antibodies. The hundreds of underperforming antibodies identified in this study were found to have been used in a large number of published articles, which should raise alarm. Encouragingly, more than half of the underperforming commercial antibodies were reassessed by the manufacturers, and many had alterations to their recommended usage or were removed from the market. This first study helps demonstrate the scale of the antibody specificity problem but also suggests an efficient strategy toward achieving coverage of the human proteome; mine the existing commercial antibody repertoire, and use the data to focus new renewable antibody generation efforts.

Comparing attentional disengagement between Prolific and MTurk samples

Attention often disengages from primary tasks in favor of secondary tasks (i.e., multitasking) and task-unrelated thoughts (i.e., mind wandering). We assessed whether attentional disengagement, in the context of a cognitive task, can substantially differ between samples from commonly used online participant recruitment platforms, Prolific and Mechanical Turk (MTurk). Initially, eighty participants were recruited through Prolific to perform an attention task in which the risk of losing points for errors was varied (high risk = 80% chance of loss, low risk = 20% chance of loss). Attentional disengagement was measured via task performance along with self-reported mind wandering and multitasking. On Prolific, we observed surprisingly low levels of disengagement. We then conducted the same experiment on MTurk. Strikingly, MTurk participants exhibited more disengagement than Prolific participants. There was also an interaction between risk and platform, with the high-risk group exhibiting less disengagement, in terms of better task performance, than the low-risk group, but only on MTurk. Platform differences in individual traits related to disengagement and relations among study variables were also observed. Platform differences persisted, but were smaller, after increasing MTurk reputation criteria and remuneration in a second experiment. Therefore, recruitment platform and recruitment criteria could impact results related to attentional disengagement.

Bioengineering of the Marine Diatom Phaeodactylum tricornutum with Cannabis Genes Enables the Production of the Cannabinoid Precursor, Olivetolic Acid

The increasing demand for novel natural compounds has prompted the exploration of innovative approaches in bioengineering. This study investigates the bioengineering potential of the marine diatom Phaeodactylum tricornutum through the introduction of cannabis genes, specifically, tetraketide synthase (TKS), and olivetolic acid cyclase (OAC), for the production of the cannabinoid precursor, olivetolic acid (OA). P. tricornutum is a promising biotechnological platform due to its fast growth rate, amenability to genetic manipulation, and ability to produce valuable compounds. Through genetic engineering techniques, we successfully integrated the cannabis genes TKS and OAC into the diatom. P. tricornutum transconjugants expressing these genes showed the production of the recombinant TKS and OAC enzymes, detected via Western blot analysis, and the production of cannabinoids precursor (OA) detected using the HPLC/UV spectrum when compared to the wild-type strain. Quantitative analysis revealed significant olivetolic acid accumulation (0.6-2.6 mg/L), demonstrating the successful integration and functionality of the heterologous genes. Furthermore, the introduction of TKS and OAC genes led to the synthesis of novel molecules, potentially expanding the repertoire of bioactive compounds accessible through diatom-based biotechnology. This study demonstrates the successful bioengineering of P. tricornutum with cannabis genes, enabling the production of OA as a precursor for cannabinoid production and the synthesis of novel molecules with potential pharmaceutical applications.

Asphaltene-Derived Graphene Quantum Dots for Controllable Coatings on Glass, Fabrics, and Aerogels

Graphene quantum dots (GQDs) derived from natural asphaltene byproducts can produce controlled hydrophobic or hydrophilic interfaces on glass, fabrics, and aerogels. A set of facile solvent extraction methods were used to isolate and chemically prepare materials with different surface functionalities from a commercially derived asphaltene precursor. The organic-soluble fraction was used to create hydrophobic and water-repellent surfaces on glass and cotton fabrics. The GQD solutions could also penetrate the pores of a silica aerogel, rendering it hydrophobic. Alternatively, by extracting the more polar fraction of the GQDs and oxidizing their surfaces, we also demonstrate strongly hydrophilic coatings. This work shows that naturally abundant GQD-containing materials can produce interfaces with the desired wettability properties through a straightforward tuning of the solvent extraction procedure. Owing to their natural abundance, low toxicity, and strong fluorescence, asphaltene-derived GQDs could thus be applied, in bulk, toward a wide range of tunable surface coatings. This approach, moreover, uses an important large-scale hydrocarbon waste material, thereby offering a sustainable alternative to the disposal of asphaltene wastes.

Young temperate tree species show different fine root acclimation capacity to growing season water availability

Background and aims

Changes in water availability during the growing season are becoming more frequent due to climate change. Our study aimed to compare the fine-root acclimation capacity (plasticity) of six temperate tree species aged six years and exposed to high or low growing season soil water availability over five years.

Methods

Root samples were collected from the five upper strata of mineral soil to a total soil depth of 30 cm in monoculture plots of Acer saccharum Marsh., Betula papyrifera Marsh., Larix laricina K. Koch, Pinus strobus L., Picea glauca (Moench) Voss and Quercus rubra L. established at the International Diversity Experiment Network with Trees (IDENT) field experiment in Sault Ste. Marie, Ontario, Canada. Four replicates of each monoculture were subjected to high or low water availability treatments.

Results

Absorptive fine root density increased by 67% for Larix laricina, and 90% for Picea glauca, under the high-water availability treatment at 0-5 cm soil depth. The two late successional, slower growing tree species, Acer saccharum and Picea glauca, showed higher plasticity in absorptive fine root biomass in the upper 5 cm of soil (PIv = 0.36 & 0.54 respectively), and lower plasticity in fine root depth over the entire 30 cm soil profile compared to the early successional, faster growing tree species Betula papyrifera and Larix laricina.

Conclusion

Temperate tree species show contrasting acclimation responses in absorptive fine root biomass and rooting depth to differences in water availability. Some of these responses vary with tree species successional status and seem to benefit both early and late successional tree species.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11104-023-06377-w.

A model of replicating coupled oscillators generates naturally occurring cell networks

When a founder cell and its progeny divide with incomplete cytokinesis, a network forms in which each intercellular bridge corresponds to a past mitotic event. Such networks are required for gamete production in many animals, and different species have evolved diverse final network topologies. Although mechanisms regulating network assembly have been identified in particular organisms, we lack a quantitative framework to understand network assembly and inter-species variability. Motivated by cell networks responsible for oocyte production in invertebrates, where the final topology is typically invariant within each species, we devised a mathematical model for generating cell networks, in which each node is an oscillator and, after a full cycle, the node produces a daughter to which it remains connected. These cell cycle oscillations are transient and coupled via diffusion over the edges of the network. By variation of three biologically motivated parameters, our model generates nearly all such networks currently reported across invertebrates. Furthermore, small parameter variations can rationalize cases of intra-species variation. Because cell networks outside of the ovary often form less deterministically, we propose model generalizations to account for sources of stochasticity.

Face and Predictive Validity of MI-RAT (Montreal Induction of Rat Arthritis Testing), a Surgical Model of Osteoarthritis Pain in Rodents Combined with Calibrated Exercise

Validating animal pain models is crucial to enhancing translational research and response to pharmacological treatment. This study investigated the effects of a calibrated slight exercise protocol alone or combined with multimodal analgesia on sensory sensitivity, neuroproteomics, and joint structural components in the MI-RAT model. Joint instability was induced surgically on day (D) 0 in female rats (N = 48) distributed into sedentary-placebo, exercise-placebo, sedentary-positive analgesic (PA), and exercise-PA groups. Daily analgesic treatment (D3-D56) included pregabalin and carprofen. Quantitative sensory testing was achieved temporally (D-1, D7, D21, D56), while cartilage alteration (modified Mankin's score (mMs)) and targeted spinal pain neuropeptide were quantified upon sacrifice. Compared with the sedentary-placebo (presenting allodynia from D7), the exercise-placebo group showed an increase in sensitivity threshold (p < 0.04 on D7, D21, and D56). PA treatment was efficient on D56 (p = 0.001) and presented a synergic anti-allodynic effect with exercise from D21 to D56 (p < 0.0001). Histological assessment demonstrated a detrimental influence of exercise (mMs = 33.3%) compared with sedentary counterparts (mMs = 12.0%; p < 0.001), with more mature transformations. Spinal neuropeptide concentration was correlated with sensory sensitization and modulation sites (inflammation and endogenous inhibitory control) of the forced mobility effect. The surgical MI-RAT OA model coupled with calibrated slight exercise demonstrated face and predictive validity, an assurance of higher clinical translatability.

Dietary counselling plus omega-3 supplementation in the treatment of generalized anxiety disorder: protocol for a randomized wait-list controlled pilot trial (the "EASe-GAD Trial")

BACKGROUND

Anxiety disorders are prevalent and disabling conditions involving excessive worry and tension. Generalized anxiety disorder (GAD), the most common anxiety disorder, affects 5% of individuals from high-income countries and many individuals report that treatment options are not accessible, effective, or tolerable. Clinical evidence suggests that nutrition interventions, based on the Mediterranean diet and supplementation of omega-3 fatty acids, can significantly improve symptoms of depression; however, the effect of nutrition interventions on anxiety symptoms has not been studied in a clinical population. The primary objective of the present study is to assess the feasibility and acceptability of a dietary counselling and omega-3 fatty acid supplementation intervention delivered to adult women with GAD. The secondary objectives include assessing changes in anxiety symptom severity, assessing changes in quality of life, assessing changes in biomarkers, and evaluating the components of the program.

METHODS

This study is a randomized, wait-list controlled pilot trial delivering a 12-week, dietary counselling intervention and omega-3 supplementation to 50 adult women with GAD. Participants will complete seven individual counselling sessions which include education, personalized recommendations, mindful eating techniques, motivational interviewing, and goal setting. They will be provided with recipes, instructional videos, and food items. The intervention is designed based on the Social Cognitive Theory and previous research that has been done by the author team to identify dietary constituents with the most evidence to support their use in the treatment of anxiety disorders. Questionnaires and blood work will be completed at baseline, after the waiting period (for those in the waitlist group), and after the intervention.

DISCUSSION

Results from this study will lay the foundation for future large-scale studies in this area and may provide preliminary evidence of the role of diet counselling and omega-3 supplementation in the management of GAD. Research on the role of nutrition in psychiatric care has been identified as a priority by a number of international organizations. The present trial directly addresses the call for the research that is most needed to advance the field.

TRIAL REGISTRATION

This protocol was registered at ClinicalTrials.gov on October 10, 2022; NCT05573672 . Trial sponsor: The Canadian College of Naturopathic Medicine, 1255 Sheppard Ave E, Toronto, ON M2K 1E2, 416-498-1255. Steering committee: Composed of MA, LL, KC, IvdW, SM, UN, AJ. The committee meets monthly to oversee the trial. Protocol identifier: CCNM_EASe-GADCT_2201v4.

A pelvic kinematic approach for calculating hip angles for active hip disarticulation prosthesis control

BACKGROUND

Control system design for a microprocessor-controlled hip-knee-ankle-foot (HKAF) prosthesis is a challenge since hip disarticulation amputees lack the entire leg and, therefore, only have pelvis movement as user-guided input. This research proposes a method for determining hip joint angles from pelvis movement in a control system for the next generation of powered prostheses.

METHOD

Three-dimensional pelvic motion and stance time of 10 transfemoral (TF) prosthetic users were used to identify important features and to develop an algorithm to calculate hip angles from pelvis movement based on correlation and linear regression results. The algorithm was then applied to a separate (independent) TF group to validate algorithm performance.

RESULTS

The proposed algorithm calculated viable hip angles during walking by utilizing pelvic rotation, pelvic tilt, and stance time. Small angular differences were found between the algorithm results and motion capture data. The greatest difference was for hip maximum extension angle (2.5 ± 2.0°).

CONCLUSIONS

Since differences between algorithm output and motion data were within participant standard deviations, the developed algorithm could be used to determine the desired hip angle from pelvis movements. This study will aid the future development of gait control systems for new active HKAF prostheses.

A comprehensive calibration of integrated magnetron sputtering and plasma enhanced chemical vapor deposition for rare-earth doped thin films

A new integrated deposition system taking advantage of magnetron sputtering and electron cyclotron-plasma enhanced chemical vapour deposition (IMS ECR-PECVD) is presented that mitigates the drawbacks of each fabrication system. This tailor-made system provides users with highly homogeneous and pure thin films with less undesired hydrogen and well-controlled rare-earth concentration compared to existing methods of rare-earth doping, such as metalorganic powders, sputtering, and ion implantation. We established the first comprehensive report on the deposition parameters of argon flow and sputtering power to achieve desired rare-earth concentrations in a wide composition range of terbium (Tb) doped-silicon oxide (Tb:SiOx) matrices including silicon-rich (x < 2), oxygen-rich (x > 2), and stoichiometric silicon oxide (x = 2). The deposition parameters to fabricate crystalline structure (Tb2Si2O7) in oxygen-rich samples are reported where Tb ions are optically active. IMS ECR-PECVD pushes the solubility limit of the rare-earth dopant in silicon films to 17 at.% for the desired future nanophotonic devices.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1557/s43578-023-01207-2.

Mycorrhizal response of Solanum tuberosum to homokaryotic versus dikaryotic arbuscular mycorrhizal fungi

Arbuscular mycorrhizal fungi (AMF) are obligate plant symbionts of most land plants. In these organisms, thousands of nuclei that are either genetically similar (homokaryotic) or derived from two distinct parents (dikaryotic) co-exist in a large syncytium. Here, we investigated the impact of these two nuclear organizations on the mycorrhizal response of potatoes (Solanum tuberosum) by inoculating four potato cultivars with eight Rhizophagus irregularis strains individually (four homokaryotic and four dikaryotic). By evaluating plant and fungal fitness-related traits four months post inoculation, we found that AMF genetic organization significantly affects the mycorrhizal response of host plants. Specifically, homokaryotic strains lead to higher total, shoot, and tuber biomass and a higher number of tubers, compared to dikaryotic strains. However, fungal fitness-related traits showed no clear differences between homokaryotic and dikaryotic strains. Nucleotype content analysis of single spores confirmed that the nucleotype ratio of AMF heterokaryon spores can shift depending on host identity. Together, these findings continue to highlight significant ecological differences derived from the two distinct genetic organizations in AMF.

Psychophysiological models of hypovigilance detection: A scoping review

Hypovigilance represents a major contributor to accidents. In operational contexts, the burden of monitoring/managing vigilance often rests on operators. Recent advances in sensing technologies allow for the development of psychophysiology-based (hypo)vigilance prediction models. Still, these models remain scarcely applied to operational situations and need better understanding. The current scoping review provides a state of knowledge regarding psychophysiological models of hypovigilance detection. Records evaluating vigilance measuring tools with gold standard comparisons and hypovigilance prediction performances were extracted from MEDLINE, PsychInfo, and Inspec. Exclusion criteria comprised aspects related to language, non-empirical papers, and sleep studies. The Quality Assessment tool for Diagnostic Accuracy Studies (QUADAS) and the Prediction model Risk Of Bias ASsessment Tool (PROBAST) were used for bias evaluation. Twenty-one records were reviewed. They were mainly characterized by participant selection and analysis biases. Papers predominantly focused on driving and employed several common psychophysiological techniques. Yet, prediction methods and gold standards varied widely. Overall, we outline the main strategies used to assess hypovigilance, their principal limitations, and we discuss applications of these models.

Simulating fate and transport of non-steroidal anti-inflammatory drugs using Root Zone Water Quality Model 2

The fate and transport of non-steroidal anti-inflammatory drugs (NSAIDs) in soil are determined by various processes, and the complexity of the system lends itself to the use of computer simulation models to help understand it. This study demonstrated the first attempt to use empirical data from lab incubation and field studies to parameterize and test a process-based agricultural systems model, Root Zone Water Quality Model 2 (RZWQM2), to simulate the fate and transport of naproxen (NPX), ibuprofen (IBF), and ketoprofen (KTF) in field-based lysimeters amended with alkaline-treated biosolids (ATBs). The model calibrated for the soil-water balance module and contaminant transport module was used to predict water seepage through the soil profile in 2017 and 2018 within a 15% error of the field measured data, with model performance statistics such as Nash-Sutcliffe model efficiency (NSE) and R2 all greater than 0.70. The overall predicted percent recovery of initial spiked NSAIDs in both soil and water samples, after further calibration of the contaminant transport module, was within the same order of magnitude as the measured data. The model underestimated the percent recovery of initial spiked NSAIDs at the 30- to 55-cm soil depth for all treatments on day 3. The calibrated soil subsurface aerobic half-lives of NPX and IBF were found to be considerably lower than their laboratory-measured half-lives obtained from the incubation study. The overall performance of RZWQM2 in simulating the soil hydrology and behavior of NSAIDs in soil profiles receiving various rates of ATB amendments was satisfactory.

Synthesis of Graphene and Graphene Films with Minimal Structural Defects

Graphene is a carbon material with extraordinary properties that has been drawing a significant amount of attention in the recent decade. High-quality graphene can be produced by different methods, such as epitaxial growth, chemical vapor deposition, and micromechanical exfoliation. The reduced graphene oxide route is, however, the only current approach that leads to the large-scale production of graphene materials at a reasonable cost. Unfortunately, graphene oxide reduction normally yields graphene materials with a high defect density. Here, we introduce a new route for the large-scale synthesis of graphene that minimizes the creation of structural defects. The method involves high-quality hydrogen functionalization of graphite followed by thermal dehydrogenation. We also demonstrated that the hydrogenated graphene synthesis route can be used for the preparation of high-quality graphene films on glass substrates. A reliable method for the preparation of these types of films is essential for the widespread implementation of graphene devices. The structural evolution from the hydrogenated form to graphene, as well as the quality of the materials and films, was carefully evaluated by Raman spectroscopy.

Machine Learning Analysis of Raman Spectra To Quantify the Organic Constituents in Complex Organic-Mineral Mixtures

Important decisions in local agricultural policy and practice often hinge on the soil's chemical composition. Raman spectroscopy offers a rapid noninvasive means to quantify the constituents of complex organic systems. But the application of Raman spectroscopy to soils presents a multifaceted challenge due to organic/mineral compositional complexity and spectral interference arising from overwhelming fluorescence. The present work compares methodologies with the capacity to help overcome common obstacles that arise in the analysis of soils. We created conditions representative of these challenges by combining varying proportions of six amino acids commonly found in soils with fluorescent bentonite clay and coarse mineral components. Referring to an extensive data set of Raman spectra, we compare the performance of the convolutional neural network (CNN) and partial least-squares regression (PLSR) multivariate models for amino acid composition. Strategies employing volume-averaged spectral sampling and data preprocessing algorithms improve the predictive power of these models. Our average test R2 for PLSR models exceeds 0.89 and approaches 0.98, depending on the complexity of the matrix, whereas CNN yields an R2 range from 0.91 to 0.97, demonstrating that classic PLSR and CNN perform comparably, except in cases where the signal-to-noise ratio of the organic component is very low, whereupon CNN models outperform. Artificially isolating two of the most prevalent obstacles in evaluating the Raman spectra of soils, we have characterized the effect of each obstacle on the performance of machine learning models in the absence of other complexities. These results highlight important considerations and modeling strategies necessary to improve the Raman analysis of organic compounds in complex mixtures in the presence of mineral spectral components and significant fluorescence.

A New and Rapid HPLC Method to Determine the Degree of Deacetylation of Glutaraldehyde-Cross-Linked Chitosan

Chitosan is a linear biopolymer composed of D-glucosamine and N-acetylglucosamine units. The percentage of D-glucosamine in the polymeric chain can vary from one sample to another and is expressed as the degree of deacetylation (DDA). Since this parameter has an impact on many properties, its determination is often critical, and potentiometric titration is a common analytical technique to measure the DDA. Cross-linking with glutaraldehyde is one of the most explored modifications of chitosan; however, the determination of the DDA for the resulting reticulated chitosan resins can be challenging. In this paper, we report a new, rapid, and efficient method to determine the DDA of glutaraldehyde-cross-linked chitosan resins via HPLC. This method relies on the use of 2,4-dinitrophenylhydrazine (DNPH) as a derivatizing agent to measure the level of reticulation of the polymer (LR) after the reticulation step. In this study, we prepare three calibration curves (with an R2 value over 0.92) for three series of reticulated polymers covering a large range of reticulation levels to demonstrate that a correlation can be established between the LR established via HPLC and the DDA obtained via titration. The polymers are derived from three different chitosan starting materials. These standard calibration curves are now used on a routine basis in our lab, and the HPLC method has allowed us to change our DDA analysis time from 20 h to 5 min.

Development of a Novel In Vitro Model to Study Lymphatic Uptake of Drugs via Artificial Chylomicrons

The lymphatic system plays a crucial role in the absorption of lipophilic drugs, making it an important route for drug delivery. In this study, an in vitro model using Intralipid® was developed to investigate the lymphatic uptake of drugs. The model was validated using cannabidiol, halofantrine, quercetin, and rifampicin. Remarkably, the uptake of these drugs closely mirrored what would transpire in vivo. Furthermore, adding peanut oil to the model system significantly increased the lymphatic uptake of rifampicin, consistent with meals containing fat stimulating lymphatic drug uptake. Conversely, the inclusion of pluronic L-81 was observed to inhibit the lymphatic uptake of rifampicin in the model. This in vitro model emerges as a valuable tool for investigating and predicting drug uptake via the lymphatic system. It marks the first phase in developing a physiologically based predictive tool that can be refined further to enhance the precision of drug interaction predictions with chylomicrons and their subsequent transport via the lymphatic system. Moreover, it can be employed to explore innovative drug formulations and excipients that either enhance or hinder lymphatic drug uptake. The insights gained from this study have significant implications for advancing drug delivery through the lymphatic system.

Physician perspectives on chronic pain management: barriers and the use of eHealth in the COVID-19 era

BACKGROUND

Chronic pain is a highly prevalent and disabling condition which is often undertreated and poorly managed in the community. The emergence of COVID-19 has further complicated pain care, with an increased prevalence of chronic pain and mental health comorbidities, and burnout among physicians. While the pandemic has led to a dramatic increase in virtual health care visits, the uptake of a broader range of eHealth technologies remains unclear. The present study sought to better understand physicians' current needs and barriers in providing effective pain care within the context of COVID-19, as well as gauge current use, interest, and ongoing barriers to eHealth implementation.

METHODS

A total of 100 practicing physicians in British Columbia, Canada, completed a brief online survey.

RESULTS

The sample was comprised of physicians practicing in rural and urban areas (rural = 48%, urban = 42%; both = 10%), with the majority (72%) working in family practice. The most prominent perceived barriers to providing chronic pain care were a lack of interdisciplinary treatment and allied health care for patients, challenges related to opioid prescribing and management, and a lack of time to manage the complexities of chronic pain. Moreover, despite expressing considerable interest in eHealth for chronic pain management (82%), low adoption rates were observed for several technologies. Specifically, only a small percentage of the sample reported using eHealth for the collection of intake data (21%), patient-reported outcomes (14%), and remote patient monitoring (26%). The most common perceived barriers to implementation were cost, complexity, and unfamiliarity with available options.

CONCLUSIONS

Findings provide insight into physicians' ongoing needs and barriers in providing effective pain management during the COVID-19 pandemic. Despite the potential for eHealth technologies to help address barriers in pain care, and strong interest from physicians, enhanced useability, education and training, and funding are likely required to achieve successful implementation of a broader range of eHealth technologies in the future.

Unleashing the piezoelectric potential of PVDF: a study on phase transformation from gamma (γ) to beta (β) phase through thermal contact poling

Polyvinylidene fluoride (PVDF) is known for its piezoelectric properties. This material has different crystalline phases, alpha (α), beta (β) and gamma (γ), where the β-phase, in particular, is related to the piezoelectric behavior of PVDF. While the transformation from the α-phase to β-phase in PVDF is well-documented and widely studied, the transformation from γ- to β-phase has not yet been fully explored. However, when PVDF is produced by certain solution-based methods it can adopt its γ-form, which is not as piezoelectric as the β-phase. Hence, this study aims to bridge this gap by investigating the transformation from γ- to β-phase in PVDF nanocomposites films obtained from solution-based techniques. Our PVDF nanocomposite is made by solvent evaporation-assisted 3D printing of PVDF's nanocomposite with barium-titanate nanoparticles (BTO). To achieve the γ- to β-phase transformation, we first highlight the importance of annealing in the successful poling of PVDF samples. We then perform an in-depth analysis of the α-, β- and γ-crystallographic phases of PVDF-BTO using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). We observed that after annealing but before poling, the PVDF-BTO nanocomposite contains 76% of β + γ phases, the majority of which is the γ-phase. Poling of these samples resulted in the combination of the β + γ phases reaching 93% with the appearance of 40% of absolute fraction of the β-phase. We then demonstrated that the fraction of β-phase in the nanocomposite - as indicated by the 1275 cm-1 peak in PVDF's FTIR spectra - is not uniform on the surface area of the film. Additionally, the value of the absolute β-phase content also depends on the poling field's direction. Our work reveals that while considering PVDF's piezoelectric behavior, it is critical to be aware of these nuances and this article offers essential insights on how to address them. Overall, this study provides a step-by-step guideline to enhance the piezoelectricity of PVDF-based nanocomposites for sensing applications.

Automated, High-Throughput Analysis of Tire-Derived p-Phenylenediamine Quinones (PPDQs) in Water by Online Membrane Sampling Coupled to MS/MS

The tire-derived contaminant N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6-PPDQ) was recently identified as a potent toxin to coho salmon (Oncorhynchus kisutch). Studies investigating 6-PPDQ have employed solid-phase extraction (SPE) or liquid-liquid extraction (LLE) with liquid chromatography-mass spectrometry (LC-MS), providing excellent sensitivity and selectivity. However, cleanup and pre-enrichment steps (SPE/LLE) followed by chromatographic separation can be time- and cost-intensive, limiting sample throughput. The ubiquitous distribution of 6-PPDQ necessitates numerous measurements to identify hotspots for targeted mitigation. We recently developed condensed phase membrane introduction mass spectrometry (CP-MIMS) for rapid 6-PPDQ analysis (2.5 min/sample), with a simple workflow and low limit of detection (8 ng/L). Here, we describe improved quantitation using isotopically labeled internal standards and inclusion of a suite of PPDQ analogues. A low-cost autosampler and data processing software were developed from a three-dimensional (3D) printer and Matlab to fully realize the high-throughput capabilities of CP-MIMS. Cross-validation with a commercial LC-MS method for 10 surface waters provides excellent agreement (slope: 1.01; R2 = 0.992). We employ this analytical approach to probe fundamental questions regarding sample stability and sorption of 6-PPDQ under lab-controlled conditions. Further, the results for 192 surface water samples provide the first spatiotemporal characterization of PPDQs on Vancouver Island and the lower mainland of British Columbia.

Locking solutions for prevention of central venous access device complications in the adult critical care population: A systematic review

BACKGROUND

The objective of this systematic review is to determine the extent and quality of evidence for use of different types of locking fluids to prevent central venous access device complications in adult critical care patients. Specifically, rates of catheter-related bloodstream infection, colonization, and occlusion were considered. All types of devices were included in the review: central venous catheters, peripherally- inserted central catheters and hemodialysis catheters.

METHODS

Eligibility criteria. Papers had to include adult (>18 years old) critical care patients, be experimental trials, conducted in North America and Europe, and published in peer-reviewed journals from 2010 onwards. Information sources. A search of Medline and EMBASE databases was performed. The search is current as of November 28th, 2022. Risk of bias. The Cochrane Risk of Bias 2 and the Risk of Bias In Non-Randomized Studies of Intervention tools were used to assess the risk of bias in included studies.

RESULTS

Included studies. A total of 240 paper titles and abstracts underwent review, of these seven studies met the final criteria for quality appraisal. A total of three studies earned a low risk of bias quality appraisal.

DISCUSSION

Limitations of evidence. Due to heterogeneity of types of locking fluids investigated and small number of studies identified, meta-analysis of results was not possible. Interpretation. Out of all fluids investigated, only citrate 46.7% was found to statistically reduce central venous access device complication rates. This systematic review has also identified a gap in the literature regarding studies of locking fluids that are adequately powered in this patient population.

FUTURE DIRECTIONS

Future research should include investigations and use of novel locking fluids with more effective properties against complications. It is imperative that future studies are adequately powered, randomized controlled trials in this patient population to facilitate optimal evidence-based care.