Quantitative analysis of tetrahydrocannabinol isomers and other toxicologically relevant drugs in blood

A multi-analyte liquid chromatography-tandem mass spectrometry (LC-MS/MS) method is described, involving the separation of delta-9-tetrahydrocannabinol (delta-9-THC) and delta-8-THC in addition to other commonly encountered drugs and metabolites. Briefly, sample preparation involved an alkaline liquid-liquid extraction (methyl tert-butyl ether) of blood (100 μl). The solvent layer was transferred, evaporated to dryness, reconstituted, and samples then separated on an Agilent Poroshell 120 EC-C18 100 Å (50 mm × 3.0 mm, 2.7 μm) analytical column using a multi-step gradient elution of 50 mM ammonium formate in water (pH 3.5) and 0.1% formic acid in methanol over 14 min. A SCIEX Triple Quad 6500+ system operating in scheduled multiple reaction monitoring and positive electrospray ionization was used for detection. There were no interferences, and matrix effects were generally acceptable (±20% of neat response). Linearity was achieved within the calibration range, including methylamphetamine (MA) (10-1000 ng/ml), 3,4-methylenedioxy-N-methylamphetamine (MDMA) (10-1,000 ng/ml), cocaine (10-1000 ng/ml), and two THC isomers (1-100 ng/ml). Accuracies of MA, MDMA, cocaine, and two THC isomers were 3.6 to 8.9%, -1.2 to 4%, -5.3 to 5.8%, and -11 to 14%, respectively; while precision estimates of the same were 1.6 to 5.4%, 1.7 to 5.3%, 1.2 to 4.5%, and 2 to 10%, respectively. Autosampler stability and dilution integrity were within acceptable limits, and no carryover was detected at the limit of detection. This validated LC-MS/MS method made the routine identification of both delta-9-THC and delta-8-THC in blood possible.

Dorsal striatum c-Fos activity in perseverative ephrin-A2A5-/- mice and the cellular effect of low-intensity rTMS

Introduction

Overreliance on habit is linked with disorders, such as drug addiction and obsessive-compulsive disorder, and there is increasing interest in the use of repetitive transcranial magnetic stimulation (rTMS) to alter neuronal activity in the relevant pathways and for therapeutic outcomes. In this study, we researched the brains of ephrin-A2A5^-/- mice, which previously showed perseverative behavior in progressive-ratio tasks, associated with low cellular activity in the nucleus accumbens. We investigated whether rTMS treatment had altered the activity of the dorsal striatum in a way that suggested altered hierarchical recruitment of brain regions from the ventral striatum to the dorsal striatum, which is linked to abnormal habit formation.

Methods

Brain sections from a limited number of mice that underwent training and performance on a progressive ratio task with and without low-intensity rTMS (LI-rTMS) were taken from a previous study. We took advantage of the previous characterization of perseverative behavior to investigate the contribution of different neuronal subtypes and striatal regions within this limited sample. Striatal regions were stained for c-Fos as a correlate of neuronal activation for DARPP32 to identify medium spiny neurons (MSNs) and for GAD67 to identify GABA-ergic interneurons.

Results and discussion

Contrary to our hypothesis, we found that neuronal activity in ephrin-A2A5^-/- mice still reflected the typical organization of goal-directed behavior. There was a significant difference in the proportion of neuronal activity across the striatum between experimental groups and control but no significant effects identifying a specific regional change. However, there was a significant group by treatment interaction which suggests that MSN activity is altered in the dorsomedial striatum and a trend suggesting that rTMS increases ephrin-A2A5^-/- MSN activity in the DMS. Although preliminary and inconclusive, the analysis of this archival data suggests that investigating circuit-based changes in striatal regions may provide insight into chronic rTMS mechanisms that could be relevant to treating disorders associated with perseverative behavior.

Low intensity repetitive transcranial magnetic stimulation modulates brain-wide functional connectivity to promote anti-correlated c-Fos expression

Repetitive transcranial magnetic stimulation (rTMS) induces action potentials to induce plastic changes in the brain with increasing evidence for the therapeutic importance of brain-wide functional network effects of rTMS; however, the influence of sub-action potential threshold (low-intensity; LI-) rTMS on neuronal activity is largely unknown. We investigated whether LI-rTMS modulates neuronal activity and functional connectivity and also specifically assessed modulation of parvalbumin interneuron activity. We conducted a brain-wide analysis of c-Fos, a marker for neuronal activity, in mice that received LI-rTMS to visual cortex. Mice received single or multiple sessions of excitatory 10 Hz LI-rTMS with custom rodent coils or were sham controls. We assessed changes to c-Fos positive cell densities and c-Fos/parvalbumin co-expression. Peak c-Fos expression corresponded with activity during rTMS. We also assessed functional connectivity changes using brain-wide c-Fos-based network analysis. LI-rTMS modulated c-Fos expression in cortical and subcortical regions. c-Fos density changes were most prevalent with acute stimulation, however chronic stimulation decreased parvalbumin interneuron activity, most prominently in the amygdala and striatum. LI-rTMS also increased anti-correlated functional connectivity, with the most prominent effects also in the amygdala and striatum following chronic stimulation. LI-rTMS induces changes in c-Fos expression that suggest modulation of neuronal activity and functional connectivity throughout the brain. Our results suggest that LI-rTMS promotes anticorrelated functional connectivity, possibly due to decreased parvalbumin interneuron activation induced by chronic stimulation. These changes may underpin therapeutic rTMS effects, therefore modulation of subcortical activity supports rTMS for treatment of disorders involving subcortical dysregulation.

Cognitive Trajectories in Community-Dwelling Older Adults and Incident Dementia, Disability and Death: A 10-Year Longitudinal Study

Objective

The inter-individual variability in cognitive changes may be early indicators of major health events. We aimed to determine whether late-life cognitive trajectories were associated with incident dementia, persistent physical disability and all-cause mortality.

Methods

Data came from a cohort of older community-dwelling individuals aged 70 years or above in Australia and the United States. Global cognition, verbal fluency, episodic memory and psychomotor speed were assessed regularly at up to seven waves between 2010 and 2017. Dementia, disability in activities of daily living, and death were adjudicated between 2017 and 2020. Latent classes of cognitive trajectories over seven years were determined using group-based trajectory modeling. Multivariable logistic regression was used for the prospective associations between cognitive trajectories and these outcomes.

Results

Cognitive trajectories were defined for 16,174 participants (mean age: 78.9 years; 56.7% female) who were alive and without incident dementia or disability by 2017, among which 14,655 participants were included in the association analysis. Between three and five trajectory classes were identified depending on the cognitive test. Cognitive trajectories were strongly associated with the risk of dementia. For example, compared to those in the highest-functioning trajectory, the worst performers of episodic memory had a 37-fold increased risk of dementia (95% CI: 17.23–82.64). The lowest trajectories of both global cognition and episodic memory also predicted increased mortality risk (OR: 1.80, 95% CI: 1.28–2.52; OR: 1.61, 95% CI: 1.09–2.36, respectively), while only slow psychomotor speed was marginally associated with physical disability (OR: 2.39, 95% CI: 0.99–5.77).

Conclusions

In older individuals, cognitive trajectories appear to be early indicators of clinically relevant health outcomes. Systematic cognitive assessments as part of routine geriatric evaluation may facilitate early identification and interventions for those individuals at highest risk.

The Use of a Two-Phase Online Delphi Panel Methodology to Inform the Concurrent Development of a School-Based Ovulatory Menstrual Health Literacy Intervention and Questionnaire

Introduction

There are a high prevalence of ovulatory-menstrual (OM) dysfunction and low levels of menstrual health literacy in adolescents, yet few evidence-based OM health education resources for schools.

Method

This two-phase study used an online Delphi methodology to build consensus across thirty-five purposively selected professionals from the diverse professions of health and education. The panellists were tasked to inform the development of a school-based OM health literacy resources.

Results

In Round One, 86% of panellists determined the scope of these resources using guided and open-ended questions. The study then split into two phases which ran concurrently. In the first phase informing the intervention's development, 57% of panellists participated in Round Two, and 29% reviewed selected lessons. In the second phase informing the questionnaire's development, 51% of panellists participated in Round Two, and 69% in Round Three. The overall consensus reached for the intervention phase and questionnaire phase were 82% and 84%, respectively. The Panel's recommendations included a strengths-based position to counter menstrual stigma, teaching accurate self-report of cycle biomarkers, addressing multiple menstrual dysfunctions and adopting a whole-school approach.

Conclusion

Although time-consuming and requiring a sustained interest, this two-phase Delphi methodology offered anonymity to panellists from distinct professions which facilitated their independent contribution to developing OM health literacy school resources.

Variability in electrophysiological properties and conducting obstacles controls re-entry risk in heterogeneous ischaemic tissue

Ischaemia, in which inadequate blood supply compromises and eventually kills regions of cardiac tissue, can cause many types of arrhythmia, some life-threatening. A significant component of this is the effects of the resulting hypoxia, and concomitant hyperklaemia and acidosis, on the electrophysiological properties of myocytes. Clinical and experimental data have also shown that regions of structural heterogeneity (fibrosis, necrosis, fibro-fatty infiltration) can act as triggers for arrhythmias under acute ischaemic conditions. Mechanistic models have successfully captured these effects in silico. However, the relative significance of these separate facets of the condition, and how sensitive arrhythmic risk is to the extents of each, is far less explored. In this work, we use partitioned Gaussian process emulation and new metrics for source-sink mismatch that rely on simulations of bifurcating cardiac fibres to interrogate a model of heterogeneous ischaemic tissue. Re-entries were most sensitive to the level of hypoxia and the fraction of non-excitable tissue. In addition, our results reveal both protective and pro-arrhythmic effects of hyperklaemia, and present the levels of hyperklaemia, hypoxia and percentage of non-excitable tissue that pose the highest arrhythmic risks. This article is part of the theme issue 'Uncertainty quantification in cardiac and cardiovascular modelling and simulation'.