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Sharpe, C.

Publications and source records attributed to Sharpe, C..

3 recordsLinked to original sources
bioRxiv2025

Females with epilepsy show abnormal changes to perimenstrual sensory induced long-term potentiation

IntroductionCatamenial epilepsy refers to a cyclical exacerbation of seizure frequency and/or severity linked to stages of the menstrual cycle. To investigate the contribution of underlying excitatory and inhibitory mechanisms of this exacerbation we induced and measured long-term potentiation (LTP). Oestradiol modulates primarily NMDA receptor driven excitation and would enhance visual LTP. Allopregnanolone modulates GABA receptor mediated inhibition and would suppress visual LTP. MethodA control cohort (n = 25) and a cohort with epilepsy (n = 20) were recruited. Participants took part in a visual LTP task while EEG was recorded. Three study visits were timed to capture the mid-follicular (days +5 to +8), mid-luteal (days -9 to -5) phases, as well as the hormone withdrawal in the perimenstrual phase (days -3 to +2). Blood samples confirmed session timing. Generative computational modelling of thalamocortical changes in the EEG was paired with standard evoked potential analysis. Result17 (age 26 {+/-} 9.40) participants with epilepsy, and a control cohort of 25 (age 30 {+/-} 7.06) without epilepsy completed the study. The P2 visually evoked potential (a positive-going component of the visual event related potential waveform) was significantly more enhanced by LTP induction in the mid-follicular phase than the mid-luteal or perimenstrual phases in the control cohort (F(2, 144) =11.54, p = 0.004 corrected). In contrast, in the epilepsy cohort the P2 was significantly more potentiated in the perimenstrual phase than the mid-follicular or mid-luteal phases (F(2,108) = 12.21, p = 0.005 corrected). The effect of cycle on visual LTP was robust, with only 3/17 participants with epilepsy showing highest P2 modulation in the mid-follicular phase (which is the pattern the healthy cohort showed). The computational modelling showed that in epilepsy, the perimenstrual phase was associated with a decrease in superficial pyramidal grain control as well as decreased LTP driven modulation of feed-forward superficial connections to layer 5 and layer 6 to thalamus. DiscussionOur finding of enhanced visual LTP in the luteal phase and perimenstrual phase of females with epilepsy indicates a breakthrough of glutamatergic excitation. Given the relationship between oestrogen and n-methyl-D-aspartate (NMDA) receptor dependent LTP this is plausibly NMDA receptor driven. Several thalamocortical model parameter changes observed warrant further investigation in studies stratifying participants by catamenial epilepsy type. Overall, while research into allopregnanolone and its inhibitory effects dominate perimenstrual catamenial epilepsy research, this study justifies consideration of the role of seizure exacerbating oestradiol.

neuroscience↗
bioRxiv2024

PTPN11 Mutation Clonal Hierarchy in Acute Myeloid Leukemia

Mutations in protein tyrosine phosphatase non-receptor type 11 (PTPN11) have been considered late acquired mutations in acute myeloid leukemia (AML) development. To interrogate the ontogeny of PTPN11 mutations, we utilized single-cell DNA sequencing and identified that PTPN11 mutations can occur as initiating events in some AML patients when accompanied by strong oncogenic drivers, commonly NPM1 mutations. The co-driver role of PTPN11 mutations was confirmed in a novel murine model that exhibits an AML phenotype with early expansion of a diverse set of variably differentiated myeloid cells that engrafted into immunodeficient and immunocompetent mice. This immune diversity was reconstituted from early precursor cells when engrafted into immunodeficient mice. Moreover, immune diversity was also observed in the blast component of patient samples with NPM1 and PTPN11 mutations, providing novel antigen targets for immune based approaches in this subset of AML that is resistant to multiple targeted therapies.

cancer biology↗
bioRxiv2020

Defining the early stages of intestinal colonisation by whipworms

Whipworms are large metazoan parasites that inhabit distinct multi-intracellular epithelial burrows described as syncytial tunnels, in the large intestine of their hosts. How first-stage larvae invade host epithelia and establish infection remains unclear. Here, we investigate early infection events both using Trichuris muris infections of mice and murine caecaloids, the first in-vitro system for whipworm infection. We show that larvae degrade the mucus layers to access epithelial cells. In early syncytial tunnels, larvae are completely intracellular but woven through multiple live enterocytes and goblet cells. We also use single cell RNA sequencing for the first time to describe the mouse caecum. From infected caeca, the transcriptome data reveal the progression of infection results in cell damage and an expansion of enterocytes with a type-I interferon (IFN) signature, characterised by the expression of Isg15, instigating the host immune response to the whipworm and tissue repair. Our results unravel intestinal epithelium invasion by whipworms and reveal new specific interactions between the host and the parasite that allow the whipworm to establish its multi-intracellular niche.

immunology↗