Polarized localization of kinesin-1 and RIC-7 drives axonal mitochondria anterograde transport

Mitochondria transport is crucial for axonal mitochondria distribution and is mediated by kinesin-1-based anterograde and dynein-based retrograde motor complexes. While Miro and Milton/TRAK were identified as key adaptors between mitochondria and kinesin-1, recent studies suggest the presence of additional mechanisms. In C. elegans, ric-7 is the only single gene described so far, other than kinesin-1, that is absolutely required for axonal mitochondria localization. Using CRISPR engineering in C. elegans, we find that Miro is important but is not essential for anterograde traffic, whereas it is required for retrograde traffic. Both the endogenous RIC-7 and kinesin-1 act at the leading end to transport mitochondria anterogradely. RIC-7 binding to mitochondria requires its N-terminal domain and partially relies on MIRO-1, whereas RIC-7 accumulation at the leading end depends on its disordered region, kinesin-1, and metaxin2. We conclude that transport complexes containing kinesin-1 and RIC-7 polarize at the leading edge of mitochondria and are required for anterograde axonal transport in C. elegans.

ObsTIVA-UK: a service evaluation of obstetric total intravenous anaesthesia in the United Kingdom

We conducted a prospective observational service evaluation across the United Kingdom on the use of total intravenous anaesthesia (TIVA) for obstetric surgery between November 2022 and June 2023. The primary aim was to describe the incidence of TIVA for obstetric surgery within participating units, with secondary aims to describe maternal and neonatal postoperative recovery indicators. Of 184 maternity units in the United Kingdom, 30 (16%) contributed data to the service evaluation. There were 104 patients who underwent caesarean delivery under TIVA and 19 patients had TIVA for other reasons. Infusions of propofol and remifentanil were used in 100% and 84% of cases, respectively. Fifty-nine out of 103 live neonates (57%) required some form of respiratory support. Of the neonates with recorded data, 73% and 17% had Apgar scores < 7 at 1 and 5 min respectively. No neonates were recorded to have Apgar scores < 7 at 10 min. Further prospective research is required to investigate the impact of obstetric TIVA on maternal and neonatal outcomes and inform best practice recommendations.

4E-BP1-dependent translation in nociceptors controls mechanical hypersensitivity via TRIM32/type I interferon signaling

Activation of the mechanistic target of rapamycin complex 1 (mTORC1) contributes to the development of chronic pain. However, the specific mechanisms by which mTORC1 causes hypersensitivity remain elusive. The eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) is a key mTORC1 downstream effector that represses translation initiation. Here, we show that nociceptor-specific deletion of 4E-BP1, mimicking activation of mTORC1-dependent translation, is sufficient to cause mechanical hypersensitivity. Using translating ribosome affinity purification in nociceptors lacking 4E-BP1, we identified a pronounced translational up-regulation of tripartite motif-containing protein 32 (TRIM32), an E3 ubiquitin ligase that promotes interferon signaling. Down-regulation of TRIM32 in nociceptors or blocking type I interferon signaling reversed the mechanical hypersensitivity in mice lacking 4E-BP1. Furthermore, nociceptor-specific ablation of TRIM32 alleviated mechanical hypersensitivity caused by tissue inflammation. These results show that mTORC1 in nociceptors promotes hypersensitivity via 4E-BP1-dependent up-regulation of TRIM32/interferon signaling and identify TRIM32 as a therapeutic target in inflammatory pain.

Distinct and sex-specific expression of mu opioid receptors in anterior cingulate and somatosensory S1 cortical areas

ABSTRACT

The anterior cingulate cortex (ACC) processes the affective component of pain, whereas the primary somatosensory cortex (S1) is involved in its sensory-discriminative component. Injection of morphine in the ACC has been reported to be analgesic, and endogenous opioids in this area are required for pain relief. Mu opioid receptors (MORs) are expressed in both ACC and S1; however, the identity of MOR-expressing cortical neurons remains unknown. Using the Oprm1-mCherry mouse line, we performed selective patch clamp recordings of MOR+ neurons, as well as immunohistochemistry with validated neuronal markers, to determine the identity and laminar distribution of MOR+ neurons in ACC and S1. We found that the electrophysiological signatures of MOR+ neurons differ significantly between these 2 areas, with interneuron-like firing patterns more frequent in ACC. While MOR+ somatostatin interneurons are more prominent in ACC, MOR+ excitatory neurons and MOR+ parvalbumin interneurons are more prominent in S1. Our results suggest a differential contribution of MOR-mediated modulation to ACC and S1 outputs. We also found that females had a greater density of MOR+ neurons compared with males in both areas. In summary, we conclude that MOR-dependent opioidergic signaling in the cortex displays sexual dimorphisms and likely evolved to meet the distinct function of pain-processing circuits in limbic and sensory cortical areas.

Cold Pressor Testing and Sympathetic Nervous System Contribution to Ischemia with No Obstructive Coronary Artery Disease: Results from the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction Project

Study Objective

Cold Pressor Testing (CPT) is a known stimulus of the sympathetic nervous system (SNS). To better understand sympathetic contribution to coronary blood flow regulation in women with suspected ischemia and no obstructive coronary arteries (INOCA), we compared myocardial perfusion reserve during CPT stress cardiac magnetic resonance (CMR) imaging between women with suspected INOCA and reference subjects.

Design

Prospective cohort.

Setting

Academic hospital.

Participants

107 women with suspected INOCA and 21-age-matched reference women.

Interventions

CPT stress CMR was performed with measurement of myocardial perfusion reserve index (MPRI), adjusted for rate pressure product (MPRI_RPP). Invasive coronary function testing in a subset of INOCA women (n=42) evaluated for endothelial dysfunction in response to acetylcholine, including impaired coronary diameter response ≤0% and coronary blood flow response (ΔCBF) <50%.

Main Outcome Measure

MPRI_RPP.

Results

Compared to reference women, the INOCA group demonstrated higher resting RPP (p=0.005) and CPT MPRI_RPP (1.09±0.36 vs 0.83±0.18, p=0.002). Furthermore, INOCA women with impaired ΔCBF (n=23) had higher CPT MPRI_RPP (p=0.044) compared to reference women despite lower left ventricular ejection fraction (64±7 % vs 69±2 %, p=0.005) and mass-to-volume ratio (0.79±0.15 vs 0.62±0.09, p<0.0001). These differences in CPT MPRI_RPP did not persist after adjusting for age, body mass index, and history of hypertension. CPT MPRI_RPP among INOCA women did not differ based on defined acetylcholine responses.

Conclusions

Myocardial perfusion reserve to CPT stress is greater among women with INOCA compared to reference subjects. CPT induced a higher MPRI_RPP also in women with coronary endothelial dysfunction, suggesting a greater contribution of the SNS to coronary flow than endothelial dysfunction. Further investigation in a larger cohort is needed.

Differential Coding of Itch and Pain by a Subpopulation of Primary Afferent Neurons

Itch and pain are distinct unpleasant sensations that can be triggered from the same receptive fields in the skin, raising the question of how pruriception and nociception are coded and discriminated. Here, we tested the multimodal capacity of peripheral first-order neurons, focusing on the genetically defined subpopulation of mouse C-fibers that express the chloroquine receptor MrgprA3. Using optogenetics, chemogenetics, and pharmacology, we assessed the behavioral effects of their selective stimulation in a wide variety of conditions. We show that metabotropic Gq-linked stimulation of these C-afferents, through activation of native MrgprA3 receptors or DREADDs, evokes stereotypical pruriceptive rather than nocifensive behaviors. In contrast, fast ionotropic stimulation of these same neurons through light-gated cation channels or native ATP-gated P2X3 channels predominantly evokes nocifensive rather than pruriceptive responses. We conclude that C-afferents display intrinsic multimodality, and we provide evidence that optogenetic and chemogenetic interventions on the same neuronal populations can drive distinct behavioral outputs.

Productivity costs of work loss associated with osteoarthritis in Canada from 2010 to 2031

OBJECTIVE

To estimate and project the productivity costs of work loss (PCWL) associated with osteoarthritis (OA) in Canada using the Population Health Model (POHEM).

DESIGN

We integrated an employment module based on 2006 Canadian Census into the previously developed microsimulation model of OA. The Canadian Community Health Survey (CCHS) Cycle 2.1 with an OA sample aged 25-64 (n = 7067) was used to calibrate the results of the employment module and to estimate the fraction of non-employment associated with OA. Probabilities of non-employment together with attributable fractions were then implemented in POHEM to estimate PCWL associated with OA from 2010 to 2031.

RESULTS

Among the OA population, 44.4% and 59.4% of non-employment due to illness was associated with OA for those not working full-year and part-year, respectively. According to POHEM projections, the size of the working age population with OA increased from 1.5 million in 2010 to 1.7 million in 2031. The PCWL associated with OA increased from $12 billion to $17.5 billion in constant 2008 Canadian dollars. Around 38% of this increase was due to the increase in OA prevalence and changes in demographics, while the rest was due to increase in real wage growth. Male and female OA patients between 55 and 64 years of age had the highest total projected PCWL, respectively.

CONCLUSIONS

The total PCWL associated with OA in Canada is estimated to be substantial and increasing in future years. Results of this study could be used to inform policies aiming to increase employment sustainability among individuals with OA.

Towards the PET radiotracer for p75 neurotrophin receptor: [(11)C]LM11A-24 shows biological activity in vitro, but unfavorable ex vivo and in vivo profile

Mature neurotrophins as well as their pro forms are critically involved in the regulation of neuronal functions. They are signaling through three distinct types of receptors: tropomyosin receptor kinase family (TrkA/B/C), p75 neurotrophin receptor (p75(NTR)) and sortilin. Aberrant expression of p75(NTR) in the CNS is implicated in a variety of neurodegenerative diseases, including Alzheimer's disease. The goal of this work was to evaluate one of the very few reported p75(NTR) small molecule ligands as a lead compound for development of novel PET radiotracers for in vivo p75(NTR) imaging. Here we report that previously described ligand LM11A-24 shows significant inhibition of carbachol-induced persistent firing (PF) of entorhinal cortex (EC) pyramidal neurons in wild-type mice via selective interaction with p75(NTR). Based on this electrophysiological assay, the compound has very high potency with an EC50<10nM. We optimized the radiosynthesis of [(11)C]LM11A-24 as the first attempt to develop PET radioligand for in vivo imaging of p75(NTR). Despite some weak interaction with CNS tissues, the radiolabeled compound showed unfavorable in vivo profile presumably due to high hydrophilicity.

Developing a digital data collection platform to measure the prevalence of sepsis in Wales

OBJECTIVE

To develop a secure, efficient, and easy-to-use data collection platform to measure the prevalence of sepsis in Wales over 24 hours.

MATERIALS AND METHODS

Open Data Kit was used on Android devices with Google App Engine and a digital data collection form.

RESULTS

A total of 184 students participated in the study using 59 devices across 16 hospitals, 1198 datasets were submitted, and 97% of participants found the Open Data Kit form easy to use.

DISCUSSION

We successfully demonstrated that by combining a reliable Android device, a free open-source data collection framework, a scalable cloud-based server, and a team of 184 medical students, we can deliver a low-cost, highly reliable platform that requires little training or maintenance, providing results immediately on completion of data collection.

CONCLUSION

Our platform allowed us to measure, for the first time, the prevalence of sepsis in Wales over 24 hours.

Dorsal Horn Parvalbumin Neurons Are Gate-Keepers of Touch-Evoked Pain after Nerve Injury

Neuropathic pain is a chronic debilitating disease that results from nerve damage, persists long after the injury has subsided, and is characterized by spontaneous pain and mechanical hypersensitivity. Although loss of inhibitory tone in the dorsal horn of the spinal cord is a major contributor to neuropathic pain, the molecular and cellular mechanisms underlying this disinhibition are unclear. Here, we combined pharmacogenetic activation and selective ablation approaches in mice to define the contribution of spinal cord parvalbumin (PV)-expressing inhibitory interneurons in naive and neuropathic pain conditions. Ablating PV neurons in naive mice produce neuropathic pain-like mechanical allodynia via disinhibition of PKCγ excitatory interneurons. Conversely, activating PV neurons in nerve-injured mice alleviates mechanical hypersensitivity. These findings indicate that PV interneurons are modality-specific filters that gate mechanical but not thermal inputs to the dorsal horn and that increasing PV inter-neuron activity can ameliorate the mechanical hypersensitivity that develops following nerve injury.

Projecting the direct cost burden of osteoarthritis in Canada using a microsimulation model

OBJECTIVES

To estimate the future direct cost of OA in Canada using a population-based health microsimulation model of osteoarthritis (POHEM-OA).

METHODS

We used administrative health data from the province of British Columbia (BC), Canada, a survey of a random sample of BC residents diagnosed with OA (Ministry of Health of BC data), Canadian Institute of Health Information (CIHI) cost data and literature estimates to populate a microsimulation model. Cost components associated with pharmacological and non-pharmacological treatments, total joint replacement (TJR) surgery, as well as use of hospital resources and management of complications arising from the treatment of osteoarthritis (OA) were included. Future costs were then simulated using the POHEM-OA model to construct profiles for each adult Canadian.

RESULTS

From 2010 to 2031, as the prevalence of OA is projected to increase from 13.8% to 18.6%, the total direct cost of OA is projected to increase from $2.9 billion to $7.6 billion, an almost 2.6-fold increase (in 2010 $CAD). From the highest to the lowest, the cost components that will constitute the total direct cost of OA in 2031 are hospitalization cost ($2.9 billion), outpatient services ($1.2 billion), alternative care and out-of-pocket cost categories ($1.2 billion), drugs ($1 billion), rehabilitation ($0.7 billion) and side-effect of drugs ($0.6 billion).

CONCLUSIONS

Projecting the future trends in the cost of OA enables policy makers to anticipate the significant shifts in its distribution of burden in the future.

Study of morphine-induced dependence in gonadectomized male and female mice

In this study we evaluated the effects of sex difference and also sex hormones on the naloxone-precipitated morphine withdrawal in both orchidectomized (ORC) male and ovariectomized (OVX) female mice. Morphine (50, 50 and 75 mg/kg/day for 4 days, s.c.) was administered to animals and at 5th day naloxone (4 mg/kg, i.p.)-precipitated morphine withdrawal signs, jumpings and the percentage of weight loss, were measured. There was no significant alteration in withdrawal jumpings between male and female mice, though weight loss was significantly higher in male ones. Jumpings was significantly lower in both OVX and ORC mice and percentage of weight loss was significantly higher in OVX mice than corresponding non-operated or sham animals. In OVX mice, E(2)V (10 mg/kg, s.c.) increased number of jumpings and decreased percentage of weight loss. Progesterone (25 mg/kg, s.c.) had no effect on jumpings, whereas it decreased weight loss in OVX mice. Testosterone (2.5 mg/kg, s.c.) increased jumpings in ORC mice while it had no effect on percentage of weight loss. Our results demonstrated that sex hormones could play a role in the morphine withdrawal syndrome in both ORC male and OVX female mice.

Real-time synthetic aperture sonar imaging using a parallel architecture

This paper describes a parallel architecture that has been developed to perform real-time synthetic aperture sonar imaging as part of the Acoustical Imaging Development (ACID) project. The project has successfully developed a synthetic aperture sonar system for producing high resolution images of the sea floor and that has been tested during a series of sea trials in May 1993 off the south coast of France. This paper describes the synthetic aperture processing system developed by the University of Newcastle upon Tyne and its use of transputer modules and associated devices in order to obtain real-time imaging performance, the software structure of the processing system and the load balancing techniques that have been developed in order to provide efficient processing. The use of a parallel distributed architecture has also allowed a processing system that can readily be extended to deliver greater computational power in the future. Images produced by the synthetic aperture processor from data collected from around the Toulon coastal region are presented. These images highlight the improvement in azimuth resolution that can be obtained from synthetic aperture processing over conventional sidescan sonars.

Portable system for the measurement of heart rate

We describe a simple RR interval recording system; it does not involve an analogue recording of ECG data on magnetic tape and does not therefore suffer from the inherent problem of tape speed variability on playback, which is a frequent cause of inaccuracies in RR interval timing. The system operates in both recording and playback modes and records of up to 60 minutes duration can be obtained without operator intervention. Its accuracy with respect to RR interval is not less than 99.5%.