Thalamic activity and biochemical changes in individuals with neuropathic pain following spinal cord injury

There is increasing evidence relating thalamic changes to the generation and/or maintenance of neuropathic pain. We have recently reported that neuropathic orofacial pain is associated with altered thalamic anatomy, biochemistry, and activity, which may result in disturbed thalamocortical oscillatory circuits. Despite this evidence, it is possible that these thalamic changes are not responsible for the presence of pain per se, but result as a consequence of the injury. To clarify this subject, we compared brain activity and biochemistry in 12 people with below-level neuropathic pain after complete thoracic spinal cord injury with 11 people with similar injuries and no neuropathic pain and 21 age- and gender-matched healthy control subjects. Quantitative arterial spinal labelling was used to measure thalamic activity, and magnetic resonance spectroscopy was used to determine changes in neuronal variability quantifying N-acetylaspartate and alterations in inhibitory function quantifying gamma amino butyric acid. This study revealed that the presence of neuropathic pain is associated with significant changes in thalamic biochemistry and neuronal activity. More specifically, the presence of neuropathic pain after spinal cord injury is associated with significant reductions in thalamic N-acetylaspartate, gamma amino butyric acid content, and blood flow in the region of the thalamic reticular nucleus. Spinal cord injury on its own did not account for these changes. These findings support the hypothesis that neuropathic pain is associated with altered thalamic structure and function, which may disturb central processing and play a key role in the experience of neuropathic pain.NHMR

Escherichia coli ItaT is a Type II Toxin that Inhibits Translation by Acetylating Isoleucyl-tRNAIle

Prokaryotic toxin-antitoxin (TA) modules are highly abundant and are involved in stress response and drug tolerance. The most common type II TA modules consist of two interacting proteins. The type II toxins are diverse enzymes targeting various essential intracellular targets. The antitoxin binds to cognate toxin and inhibits its function. Recently, TA modules whose toxins are GNAT-family acetyltransferases were described. For two such systems, the target of acetylation was shown to be aminoacyl-tRNA: the TacT toxin targets aminoacylated elongator tRNAs, while AtaT targets the amino acid moiety of initiating tRNAMet. We show that the itaRT gene pair from Escherichia coli encodes a TA module with acetyltransferase toxin ItaT that specifically and exclusively acetylates Ile-tRNAIle thereby blocking translation and inhibiting cell growth. ItaT forms a tight complex with the ItaR antitoxin, which represses the transcription of itaRT operon. A comprehensive bioinformatics survey of GNAT acetyltransferases reveals that enzymes encoded by validated or putative TA modules are common and form a distinct branch of the GNAT family tree. We speculate that further functional analysis of such TA modules will result in identification of enzymes capable of specifically targeting many, perhaps all, aminoacyl tRNAs

Primary Somatosensory Cortices Contain Altered Patterns of Regional Cerebral Blood Flow in the Interictal Phase of Migraine

The regulation of cerebral blood flow (CBF) is a complex integrated process that is critical for supporting healthy brain function. Studies have demonstrated a high incidence of alterations in CBF in patients suffering from migraine with and without aura during different phases of attacks. However, the CBF data collected interictally has failed to show any distinguishing features or clues as to the underlying pathophysiology of the disease. In this study we used the magnetic resonance imaging (MRI) technique—arterial spin labeling (ASL)—to non-invasively and quantitatively measure regional CBF (rCBF) in a case-controlled study of interictal migraine. We examined both the regional and global CBF differences between the groups, and found a significant increase in rCBF in the primary somatosensory cortex (S1) of migraine patients. The CBF values in S1 were positively correlated with the headache attack frequency, but were unrelated to the duration of illness or age of the patients. Additionally, 82% of patients reported skin hypersensitivity (cutaneous allodynia) during migraine, suggesting atypical processing of somatosensory stimuli. Our results demonstrate the presence of a disease-specific functional deficit in a known region of the trigemino-cortical pathway, which may be driven by adaptive or maladaptive functional plasticity. These findings may in part explain the altered sensory experiences reported between migraine attacks

Dynamic acetabular cup orientation during gait: a study of fast and slow walking total hip replacement patients

The dynamic orientation of total hip replacement acetabular cups during walking may vary sub-stantially from their assumed position at surgical implantation and may vary between individuals. The scale of this effect is of interest for both pre-clinical device testing and for pre-operative sur-gical planning. This work aimed to evaluate: 1) patient variation in dynamic cup orientation; 2) whether walking speed was a candidate proxy measure for the dynamic cup orientation; and 3) the relationships between dynamic cup orientation angles and planar pelvic angles. Pelvic movement data for patients with fast (n=20) and slow (n=19) self-selected walking speeds, was used to calcu-late acetabular cup inclination and version angles through gait. For aim 1, the range and extremes of acetabular cup orientation angles were analysed for all patients. Large patient to patient varia-tion was found in the range of both inclination angle (1° to 11°) and version angle (4° to 18°). The version angle was typically retroverted in comparison to the implantation position (greatest devi-ation 27o). This orientation is substantially different to the static, 0° version simplifying assump-tions in pre-clinical ‘edge loading’ testing. For aim 2, the cup orientation angles were compared between the fast and slow walking groups using statistical parametric mapping. The only signifi-cant differences observed were for cup version angle, for ~12% of the gait cycle, before toe-off (p < 0.05). Therefore, self-selected walking speed, in isolation, is not a sufficient proxy measure for dynamic acetabular orientation. For aim 3, correlations were recorded between the acetabular cup orientation angles and the planar pelvic angles. The cup inclination angle during gait was strongly correlated (Spearman’s coefficient -1) with pelvic obliquity alone, indicating that simple planar assessment could be used to anticipate range of inclination angle. The cup version angle was cor-related with both pelvic rotation and tilt (Spearman’s coefficient 0.8-1), indicating that cup version cannot be predicted directly from any single pelvic movement. This complexity, along with the interaction between inclination angle and range of version angle, supports the use of computa-tional tools to aid clinical understanding

Identification of a novel gene regulating amygdala-mediated fear extinction.

Recent years have seen advances in our understanding of the neural circuits associated with trauma-related disorders, and the development of relevant assays for these behaviors in rodents. Although inherited factors are known to influence individual differences in risk for these disorders, it has been difficult to identify specific genes that moderate circuit functions to affect trauma-related behaviors. Here, we exploited robust inbred mouse strain differences in Pavlovian fear extinction to uncover quantitative trait loci (QTL) associated with this trait. We found these strain differences to be resistant to developmental cross-fostering and associated with anatomical variation in basolateral amygdala (BLA) perineuronal nets, which are developmentally implicated in extinction. Next, by profiling extinction-driven BLA expression of QTL-linked genes, we nominated Ppid (peptidylprolyl isomerase D, a member of the tetratricopeptide repeat (TPR) protein family) as an extinction-related candidate gene. We then showed that Ppid was enriched in excitatory and inhibitory BLA neuronal populations, but at lower levels in the extinction-impaired mouse strain. Using a virus-based approach to directly regulate Ppid function, we demonstrated that downregulating BLA-Ppid impaired extinction, while upregulating BLA-Ppid facilitated extinction and altered in vivo neuronal extinction encoding. Next, we showed that Ppid colocalized with the glucocorticoid receptor (GR) in BLA neurons and found that the extinction-facilitating effects of Ppid upregulation were blocked by a GR antagonist. Collectively, our results identify Ppid as a novel gene involved in regulating extinction via functional actions in the BLA, with possible implications for understanding genetic and pathophysiological mechanisms underlying risk for trauma-related disorders

Drug use in street sex workers (DUSSK) study protocol:a feasibility and acceptability study of a complex intervention to reduce illicit drug use in drug dependent female street sex workers

INTRODUCTION: Poor health of sex workers continues to be a source of international concern. Sex work is frequently linked with problematic drug use and drug-dependent sex workers typically work on the street, experiencing the greatest risks to health compared with the general population. Street sex workers (SSWs) are much more likely to have experienced incidences of physical and sexual assault, increasing their risk of developing post-traumatic stress disorder (PTSD). We have developed a novel complex intervention designed to reduce illicit drug use in drug-dependent female SSWs which involves: female SSW drug treatment groups (provided by a specialist charity) in a female SSW setting (female sex worker charity premises) provided by female-only staff, PTSD care with eye movement desensitisation and reprocessing (EMDR) therapy provided by female staff from National Health Service (NHS) mental health services. METHODS AND ANALYSIS: A mixed methods study investigating the feasibility and acceptability of this intervention to inform the design of a future randomised controlled trial. The study aims to recruit up to 30 participants from November 2017 to March 2018 at a single site, with the intervention being delivered until December 2018. It will gather quantitative data using questionnaires and group attendance. Drug treatment group observations and in-depth interviews undertaken with up to 20 service users and 15 service providers to examine experiences and acceptability of the intervention. Study feasibility will be assessed by evaluating the recruitment and retention of participants to the intervention; the feasibility of NHS and third sector organisations working closely to coordinate care for a SSW population; the potential for specialist NHS mental health services to screen and provide EMDR therapy for drug-dependent SSWs and potential costs of implementing the intervention. ETHICS AND DISSEMINATION: This study was approved by South West-Frenchay Research Ethics Committee (REC reference: 17/SW/0033; IRAS ID: 220631) and the Health Research Authority (HRA). Findings will be disseminated through research conferences and peer-reviewed journals

Case Series: Efficacy of Polyclonal Intravenous Immunoglobulin for Refractory Clostridioides difficile Infection

Background: Intravenous immunoglobulin (IVIg) for Clostridioides difficile infection (CDI) no longer features in treatment guidelines. However, IVIg is still used by some clinicians for severe or recurrent CDI (rCDI) cases. The main objective of this study was to investigate the efficacy of IVIg and to identify possible predictors of disease resolution post IVIg administration for patients with CDI. Methods: This retrospective observational cohort study of patients ≥2 years old hospitalised with severe, relapsing, or rCDI treated with IVIg therapy was performed in a large UK tertiary hospital between April 2018 and March 2023. Scanned electronic notes from patient admissions and clinical reporting systems were used to collect relevant data. Results: In total, 20/978 patients diagnosed with CDI over the 5-year study were treated with IVIg. Twelve (60%) had hospital-onset CDI. Eleven of the twenty patients (55%) responded to treatment, with a mean of 8.6 (SD 10.7) days to disease resolution. Sixteen (80%) patients were treated for severe CDI and four (20%) for rCDI (n = 3) and relapsing CDI (n = 1). There were no statistically significant differences in possible independent predictors of disease resolution post IVIg administration between groups. There was an average of 6.2 (4.9) days to IVIg administration after diagnosis with no difference between responders and non-responders (p = 0.88) and no further significant difference in additional indicators. Four (36%) of the responders were immunosuppressed compared to just one (11%) of the non-responders (p = 0.15). Six of the responders (two with recurrent and four with severe CDI) improved rapidly within 2 days, and three of these were immunosuppressed. Conclusion: We observed disease resolution post IVIg therapy in over 50% of patients with refractory CDI. Our data also support a potential enhanced effect of IVIg in immunosuppressed individuals. Thus, the role of IVIg for CDI treatment, particularly in the immunosuppressed, warrants future case–control studies coupled to mechanistic investigations to improve care for this ongoing significant healthcare-associated infection

Cortico–Cortical Connections of Primary Sensory Areas and Associated Symptoms in Migraine

Abstract Migraine is a recurring, episodic neurological disorder characterized by headache, nausea, vomiting, and sensory disturbances. These events are thought to arise from the activation and sensitization of neurons along the trigemino–vascular pathway. From animal studies, it is known that thalamocortical projections play an important role in the transmission of nociceptive signals from the meninges to the cortex. However, little is currently known about the potential involvement of cortico–cortical feedback projections from higher-order multisensory areas and/or feedforward projections from principle primary sensory areas or subcortical structures. In a large cohort of human migraine patients (N = 40) and matched healthy control subjects (N = 40), we used resting-state intrinsic functional connectivity to examine the cortical networks associated with the three main sensory perceptual modalities of vision, audition, and somatosensation. Specifically, we sought to explore the complexity of the sensory networks as they converge and become functionally coupled in multimodal systems. We also compared self-reported retrospective migraine symptoms in the same patients, examining the prevalence of sensory symptoms across the different phases of the migraine cycle. Our results show widespread and persistent disturbances in the perceptions of multiple sensory modalities. Consistent with this observation, we discovered that primary sensory areas maintain local functional connectivity but express impaired long-range connections to higher-order association areas (including regions of the default mode and salience network). We speculate that cortico–cortical interactions are necessary for the integration of information within and across the sensory modalities and, thus, could play an important role in the initiation of migraine and/or the development of its associated symptoms

The influence of the representation of collagen fibre organisation on the cartilage contact mechanics of the hip joint

The aim of this study was to develop a finite element (FE) hip model with subject-specific geometry and biphasic cartilage properties. Different levels of detail in the representation of fibre reinforcement were considered to evaluate the feasibility to simplify the complex depth-dependent fibre pattern in the native hip joint. A FE model of a cadaveric hip with subject-specific geometry was constructed through micro-computed-tomography (µCT) imaging. The cartilage was assumed to be biphasic and fibre-reinforced with different levels of detail in the fibre representation. Simulations were performed for heel-strike, mid-stance and toe-off during walking and one-leg-stance over 1500s. It was found that the required level of detail in fibre representation depends on the parameter of interest. The contact stress of the native hip joint could be realistically predicted by simplifying the fibre representation to being orthogonally reinforced across the whole thickness. To predict the fluid pressure, depth-dependent fibre organisation is needed but specific split-line pattern on the surface of cartilage is not necessary. Both depth-dependent and specific surface fibre orientations are required to simulate the strains

Six versus 12 months' adjuvant trastuzumab in patients with HER2-positive early breast cancer: the PERSEPHONE non-inferiority RCT

Background The addition of adjuvant trastuzumab to chemotherapy has significantly improved outcomes in human epidermal growth factor receptor 2 (HER2) positive early, potentially curable breast cancer. Twelve months’ trastuzumab tested in the registration trials was adopted for standard adjuvant treatment in 2006. Subsequently similar outcomes were demonstrated using 9 weeks trastuzumab. Shorter durations were therefore tested for non-inferiority. Objectives To establish whether 6 months’ adjuvant trastuzumab is non-inferior to 12 months in HER2-positive early breast cancer using a primary endpoint of 4-year disease-free-survival (DFS). Design Phase III randomised, controlled, non-inferiority trial. Setting 152 NHS Hospitals. Participants 4088 patients with HER2-positive early breast cancer planned to receive both chemotherapy and trastuzumab. Intervention Randomisation (1:1) between six months’ or twelve months’ trastuzumab. Main outcomes Primary endpoint was DFS four years after diagnosis. Secondary endpoints were overall survival (OS), cost effectiveness, and cardiac function during trastuzumab. Assuming a 4-year DFS rate of 80% with 12 months, 4000 patients were required to demonstrate non-inferiority of 6-months (5% 1-sided significance, 85% power), defining the non-inferiority limit as no worse than 3% below the standard arm. Costs and quality-adjusted life years (QALYs) were estimated by within-trial analysis and a lifetime decision-analytic model. Results Between 4th October 2007 and 31st July 2015, 2045 patients were randomised to 12-months’ trastuzumab and 2043 to 6-months. Sixty-nine percent had ER-positive disease; 90% received anthracyclines (49% with taxanes; 41% without taxanes); 10% received taxanes without anthracyclines; 54% had trastuzumab sequentially after chemotherapy; 85% received adjuvant chemotherapy (58% were node negative). At 6.1 years median follow-up with 389 (10%) deaths, and 566 (14%) DFS events, 4-year DFS rates for the 4088 patients were 89.5% (95% CI, 88.1-90.8) in the 6-month group and 90.3% (95% CI 88.9- 91.5) in the 12-month group (Hazard Ratio 1.10; 90% CI 0.96–1.26, non-inferiority p=0.01), demonstrating non-inferiority of 6-months’ trastuzumab. Congruent results were found for OS (non-inferiority p=0.0003), and landmark analyses 6 months from starting trastuzumab (non-inferiority p=0.03 (DFS) and p=0.006 (OS)). 6-months’ trastuzumab resulted in fewer patients reporting adverse events of severe grade (365/1929 (19%) versus 460/1935 (24%) 12-month patients, p=0.0003) or stopping early because of cardiotoxicity (61/1977 (3%) versus 146/1941 (8%) 12-month patients, p<0.0001). Health economic analysis showed significantly lower lifetime costs and similar lifetime QALYs, and thus a high probability that 6 months is cost-effective compared to 12 months. Patient reported experiences on the trial highlighted fatigue, and aches and pains most frequently. Limitations The type of chemotherapy and timing of trastuzumab changed through the recruitment phase of the study as standard practice altered. Conclusions PERSEPHONE demonstrated that in HER2-positive early breast cancer 6 months’ adjuvant trastuzumab was non-inferior to 12 months. There was significantly less cardiac toxicity and fewer severe adverse events with 6 months’ treatment. Future work On-going translational work investigates patient and tumour genetic determinants of toxicity, and trastuzumab efficacy. An individual patient data meta-analysis with PHARE and other trastuzumab duration trials is planned. Trial registration ISRCTN 52968807 Funding National Institute for Health Research, Health Technology Assessment Programme (HTA Project: 06/303/98).National Institute for Health Research, Health Technology Assessment Programme (HTA Project: 06/303/98)