Biology subjects

Miller, E.

Publications and source records attributed to Miller, E..

At least 37 records · Page 2Linked to original sources

bioRxiv2025

A Wildlife Health Outbreak Response Table-top Exercise for Pandemic Preparedness Planning

Zoonotic diseases have received significantly more attention over the last few decades, emerging with increasing frequency and causing the majority of notable disease outbreaks in this century, including the COVID-19 pandemic. As human activities and shifting climate patterns induce changes in the environment that alter habitat and range of reservoir species, the potential for human and animal interactions will increase and enhance the opportunity for spillover. Thus, any emergency response preparedness planning must take into account the function and coordination of agencies across the sectors of human, animal and environmental health. Within the Commonwealth of Pennsylvania a table-top exercise was performed to evaluate a multi-agency response during a hypothetical zoonotic disease investigation. The exercise was evaluated by the participants to gain feedback on the overall process and lessons learned. Here, we describe the tabletop exercise scenario and the insights gained. We found that differences in operational structure create challenges for interdepartmental communication and in the ability to resource a coordinated response, highlighting opportunities to develop infrastructure that will facilitate future actions. A set of recommendations are outlined that may enhance cross-agency activities and promote more effective and efficient emergency response.

scientific communication and education↗

bioRxiv2025

Parkinson's Paradox: Alpha-synuclein's Selective Strike on SNc Dopamine Neurons over VTA

In synucleinopathies, including Parkinsons disease (PD), dopamine neurons in the substantia nigra pars compacta (SNc) exhibit greater vulnerability to degeneration than those in the ventral tegmental area (VTA). While -synuclein (Syn) pathology is implicated in nigral dopamine neuron loss, the mechanisms by which Syn affects neuronal activity and midbrain dopamine network connectivity prior to cell death remain unclear. This study tested the hypothesis that elevated Syn expression induces pathophysiological changes in firing activity and disrupts network connectivity dynamics of dopamine neurons before neuronal loss. We employed two mouse models of synucleinopathy: preformed Syn fibril (PFF) injection and AAV-mediated expression of human Syn (hSyn) under the control of the tyrosine hydroxylase (TH) promoter, both targeting the VTA and SNc. Four weeks post-injection, brain sections underwent histological, electrophysiological, and network analyses. Immunohistochemistry for TH, hSyn, and phospho-Ser129 Syn assessed Syn expression and dopaminergic neuron alterations. Neuronal viability was evaluated using two complementary approaches: quantification of TH+ or FOX3+ and TUNEL labeling. Importantly, these analyses revealed no significant changes in neuronal counts or TUNEL+ cells at this time point, confirming that subsequent functional assessments captured pre-neurodegenerative, Syn-induced alterations rather than late-stage neurodegeneration. Electrophysiological recordings revealed a differential effect of hSyn expression. SNc dopamine neurons exhibited significantly increased baseline firing rates, whereas VTA dopamine neurons remained unchanged. These findings indicate a region-specific vulnerability to Syn-induced hyperactivity of dopamine neurons. Further analysis revealed impaired homeostatic firing rate regulation in SNc, but not VTA, dopamine neurons, demonstrated by a reduced capacity to recover baseline firing following hyperpolarization. Collectively, our results demonstrate that, prior to neurodegeneration, elevated Syn expression differentially disrupts both basal firing activity and network stability of SNc dopamine neurons, while sparing VTA dopamine neurons. By identifying neurophysiological changes preceding dopaminergic neuron loss, these findings provide critical insights into the pathophysiological mechanisms predisposing SNc neurons to degeneration in Parkinsons disease. Significance StatementA central question in Parkinsons disease research is why dopamine neurons in the substantia nigra pars compacta (SNc) are more vulnerable than those in the ventral tegmental area (VTA). This study reveals that alpha-synuclein (Syn) pathology differentially impacts dopamine neuronal activity and network connectivity, causing changes in the SNc before neuronal loss occurs, but not in the VTA. These findings provide a mechanism to explain the differential resilience of these neighboring dopamine neuron populations and provide insights into Parkinsons disease progression. The methodologies developed in this study establish a foundation for investigating network topology in deep brain structures and its role in neurodegenerative disorders.

neuroscience↗

bioRxiv2025

Perturbed cyclic strain results in a mechanically-induced, premature senescent phenotype in cardiac fibroblasts

The cardiovascular system operates under continuous cyclic mechanical stretch, and changes in mechanics and biochemical responses observed in cardiovascular disorders activate the cardiac fibroblasts (CFs) and increase cellular senescence in the tissue. However, it is unclear if cellular senescence is initiated from biomechanical stimulus alone. Here, we subjected murine CFs to uniaxial stretch and perturbed the mechanical stimulation to examine the impact on induction of a senescent phenotype. Loss of stretch magnitude and increase in frequency, mimicking an injurious hypertrophic or fibrotic response, led to a senescence-like phenotype, including cell cycle, lamin B expression, and DNA damage. Mechanical induction of CF senescence relied on p53/p21, whereas CF senescence induction triggered by reactive oxygen species or involving a mutation in lamin A/C gene occurred through p16. Moreover, mechanical induction of premature senescence was associated with decreases in the nuclear envelope protein emerin. These results demonstrate perturbed mechanical stimulation can initiate a senescent state and altered nuclear integrity may initiate this phenotype. TeaserPerturbed mechanics initiates a premature senescent-like phenotype in cardiac fibroblasts.

biophysics↗

bioRxiv2025

Pathological α-Synuclein Perturbs Nuclear Integrity

Pathological aggregates of -synuclein are a hallmark of a group of neurodegenerative disorders collectively termed synucleinopathies. The physiological function of -synuclein, and the detrimental effects of the pathological variants of -synuclein have been widely debated, but recent evidence has suggested an emerging consensus on a critical role for -synuclein in regulating synaptic function. However, a controversial role for -synuclein in nuclear function in both normal and pathogenic states has been proposed, and the degree to which -synuclein localizes within the nucleus and subsequent impact on the nucleus are poorly understood. To begin to address this controversy, we employed synucleinopathy murine and cell culture models, as well as postmortem human Lewy Body Dementia tissue to elucidate the extent to which pathological -synuclein localizes within the nuclear compartments, and the downstream consequences of this localization. We observed pathological aggregation of -synuclein within the nucleus in both murine models and human postmortem Lewy Body Dementia cortex via quantitative super resolution microscopy. In both mouse and human brain tissue the presence of -synuclein in the nucleus correlated with abnormal morphology of nuclei. This pathological accumulation of -synuclein in the nucleus was not observed in control mice, human tissue without pathology, or control cells. We subsequently examined the mechanistic consequences of pathological accumulation of -synuclein in the nucleus. Synucleinopathy models displayed increased levels of the DNA damage marker 53BP1. Furthermore, cells with pathological -synuclein exhibited elevated markers of nuclear envelope damage and abnormal expression of nuclear envelope repair markers. Our cell culture data also suggests altered RNA localization in response to pathological -synuclein accumulation within the nucleus. Lastly, we show that nuclear Lewy-like pathology leads to increased sensitivity to nuclear targeted toxins. Taken together, these results rigorously illustrate nuclear localization of pathological -synuclein with super resolution methodology and provide novel insight into the ensuing impact on nuclear integrity and function.

neuroscience↗

bioRxiv2025

RNAprecis: Prediction of full-detail RNA conformation from the experimentally best-observed sparse parameters

We address the problem of predicting high-detail RNA structure geometry from the information available in low-detail experimental maps. Here, low-detail refers to resolutions {approx} 2.5-3.5[A], where the location of the phosphate groups and the glycosidic bonds can be determined from experimental maps but all other backbone atom positions cannot. In contrast, higher-resolution maps allow high-detail determinations of all backbone atomic positions. To this end, we first create a gold standard dataset of highly curated, experimentally supported RNA suites. Second, we develop and employ a modified version of the previously devised algorithm MINT-AGE to learn clusters that are in high correspondence with the gold standards conformational classes of suites based on 3D RNA structure. Since some of the gold standard classes are of very small size, a new modified version of MINT-AGE is able to also identify very small clusters. Third, we create a new conformer prediction algorithm, RNAprecis, which assigns low-detail structures to newly designed 3D shape coordinates. Our improvements include: (i) learned classes augmented to cover also very low sample sizes and (ii) replacing distances from clusters by Bayesian posterior probabilities. On test data containing suites modeled as conformational outliers, RNAprecis shows good results suggesting that our learning method generalizes well. In particular, we show that the modified MINT-AGE clustering can more finely delineate between previously unseen suite conformer separations. For example, the 0a conformer has been separated into two clusters seen in different structural contexts. Such new distinctions can have implications for biochemical interpretation of RNA structure.

molecular biology↗

bioRxiv2024

Membrane-bound Guanylyl Cyclase COP5/HKR1 changes ciliary beat pattern and biases cell steering during chemotaxis in Chlamydomonas reinhardtii

This study investigates the control of ciliary beat patterns during ammonium chemotaxis in the model ciliate microalgae Chlamydomonas reinhardtii. Screening the chemotaxis response of mutant strains with ciliary defects revealed that a strain lacking CAV2, the alpha subunit of the voltage-gated Ca2+ channel, is deficient in ammonium chemotaxis. CAV2 regulates the switching of the ciliary beat pattern from the asymmetric to the symmetric waveform. Strains lacking COP5/HKR1 (chlamyopsin 5/histidine kinase rhodopsin 1), a membrane-bound guanylyl cyclase, are also deficient in ammonium chemotaxis. Conversely, strains defective in phototaxis perform ammonium chemotaxis normally. Cell motility analysis revealed wild-type cells reduce the incidences of switching the ciliary beat pattern from the asymmetric to symmetric waveform when swimming up the ammonium gradient. In contrast, the COP5/HKR1 disrupted strain does not bias ciliary beat pattern switching in the gradient. This finding reveals that a membrane-bound guanylyl cyclase plays a critical role in Chlamydomonas chemotaxis signaling transduction, similarly to animal chemotaxis. On the other hand, ciliary beat pattern switching induces randomized directional changes, analogous to run-and-tumble chemotaxis of bacteria and archaea. This study reveals that Chlamydomonas signaling transduction is similar to the eukaryotic mechanism, yet the cellular locomotion follows the bacteria and archaea mechanism.

microbiology↗

bioRxiv2024

Conditional Knockout of Striatal Gnal Produces Dystonia-like Motor Phenotypes

Loss-of-function mutations in GNAL have been linked to an adult-onset, isolated dystonia that is largely indistinguishable from idiopathic dystonia. GNAL encodes Golf, a heterotrimeric G-protein subunit with a defined molecular function to increase the production of the second messenger cAMP. Golf is abundant in the striatum, and is the only stimulatory G-protein in many cell types of the striatum. Due to the defined molecular signaling pathway and expression pattern of Golf, the clear genetic link to dystonia makes GNAL an exciting target to understand the pathological mechanisms of not only this genetic dystonia, but also the larger idiopathic disease. To better understand GNAL-linked dystonia, we generated a novel genetic mouse model that allows us to conditionally knock out Gnal in a site and time-specific manner. In the current study we used genetic or AAV based approaches to express Cre to knockout striatal Gnal in our novel Gnal fl/fl model. We then performed motor behavioral testing and ex vivo whole-cell patch clamp electrophysiology of striatal spiny projection neurons to interrogate how loss of Gnal leads to dystonia. Mice with conditional striatal knockout of Gnal show hindlimb clasping, other dystonia-like postures, less motor coordination, slowness, and torticollis as compared to age-matched controls. Furthermore, striatal spiny projection neurons show increased excitability in Gnal knockout animals. These exciting data are the first to report uninduced, overt dystonia in a mouse model of GNAL-linked dystonia, and directly correlate these with changes in spiny projection neuron electrophysiological properties. Our results show that adult loss of Gnal in the striatum leads to the development of dystonia, through homeostatic, paradoxical increases in spiny projection neuron excitability, and suggest that therapeutic strategies aimed at decreasing this hyperexcitable phenotype may provide symptomatic relief for patients with disease. One Sentence Summary: When Gnal is knocked out in the striatum of mice we observe overt behavioral symptoms and hyperexcitability in striatal spiny projection neurons.

neuroscience↗

bioRxiv2024

In vivo Antibody Painting for Next Generation Weight Loss Drugs

Peptide-based therapeutics are currently in great demand but often suffer from rapid clearance and accumulation in off-target tissues which continue to present barriers in their clinical translation. Here, we developed an electrophilic peptide for the attachment of therapeutics to native immunoglobulin (IgG) in vivo, enabling the bioorthogonal covalent linkage, or painting, of peptide drugs of choice to circulating IgGs directly in live animals. Native IgG painting with glucagon-like peptide-1 (GLP-1) results in sustained body weight loss and prolonged blood glucose management after one dose. Such technology might revolutionize the next generation of long-acting peptide-based medicines.

bioengineering↗

bioRxiv2024

Leveraging Crosslinker Diffusion to Template Stiffness Gradients in Alginate Hydrogels

Mechanobiology drives many important cell biological behaviors such as stem cell differentiation, cancer drug resistance and cell migration up stiffness gradients, a process called durotaxis. The development of 3D hydrogel systems with tunable 2D mechanical gradient patterns affords the ability to study these mechanosensitive cell behaviors to understand cancer invasion or enhance wound healing through directed migration. In this paper, we developed an approach to spatially imprint within alginate hydrogels, gradients in mechanical properties that can be used to probe mechanobiology. Stencils were easily designed and fabricated using a common craft cutter to control the presentation of a calcium crosslinking solution to alginate gels. Different stencil shapes result in different gradients in opacity that can be imprinted into both thick and thin alginate gels of arbitrary 2D shape. The steepness of the opacity gradient as well as the maximum opacity can be controlled based on reproducible crosslinking kinetics regulated through calcium concentration and gradient developing time. Calcium crosslinking results in both opacity changes as well as increases in elastic modulus in the bulk hydrogel. Opacity correlates with elastic modulus, allowing it to be used as a proxy for local elastic modulus. Functionalized alginate gels with collagen and imprinting stiffness gradients within them resulted in cell invasion that was spatially dependent, where stiffer regions facilitated deeper invasion of breast cancer cells. Consequently, this stenciling approach represents a facile way to control stiffness gradients in alginate gels in order to study mechanosensitive cellular behavior. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=45 SRC="FIGDIR/small/599742v2_ufig1.gif" ALT="Figure 1"> View larger version (14K): org.highwire.dtl.DTLVardef@1182404org.highwire.dtl.DTLVardef@1e4bfb1org.highwire.dtl.DTLVardef@e52778org.highwire.dtl.DTLVardef@8237bd_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2024

Towards optical measurements of membrane potential values in Bacillus subtilis using fluorescence lifetime

Membrane potential (MP) changes can provide a simple readout of bacterial functional and metabolic state or stress levels. While several optical methods exist for measuring fast changes in MP in excitable cells, there is a dearth of such methods for absolute and precise measurements of steady-state membrane potentials (MPs) in bacterial cells. Conventional electrode-based methods for the measurement of MP are not suitable for calibrating optical methods in small bacterial cells. While optical measurement based on Nernstian indicators have been successfully used, they do not provide absolute or precise quantification of MP or its changes. We present a novel, calibrated MP recording approach to address this gap. In this study, we used a fluorescence lifetime-based approach to obtain a single-cell resolved distribution of the membrane potential and its changes upon extracellular chemical perturbation in a population of bacterial cells for the first time. Our method is based on (i) a unique VoltageFluor (VF) optical transducer, whose fluorescence lifetime varies as a function of MP via photoinduced electron transfer (PeT) and (ii) a quantitative phasor-FLIM analysis for high-throughput readout. This method allows MP changes to be easily visualized, recorded and quantified. By artificially modulating potassium concentration gradients across the membrane using an ionophore, we have obtained a Bacillus subtilis-specific MP versus VF lifetime calibration and estimated the MP for unperturbed B. subtilis cells to be -65 mV (in MSgg), -127 mV (in M9) and that for chemically depolarized cells as -14 mV (in MSgg). We observed a population level MP heterogeneity of [~]6-10 mV indicating a considerable degree of diversity of physiological and metabolic states among individual cells. Our work paves the way for deeper insights into bacterial electrophysiology and bioelectricity research.

biophysics↗

bioRxiv2024

Empowering bioinformatics communities with Nextflow and nf-core

Standardised analysis pipelines are an important part of FAIR bioinformatics research. Over the last decade, there has been a notable shift from point-and-click pipeline solutions such as Galaxy towards command-line solutions such as Nextflow and Snakemake. We report on recent developments in the nf-core and Nextflow frameworks that have led to widespread adoption across many scientific communities. We describe how adopting nf-core standards enables faster development, improved interoperability, and collaboration with the >8,000 members of the nf-core community. The recent development of Nextflow Domain-Specific Language 2 (DSL2) allows pipeline components to be shared and combined across projects. The nf-core community has harnessed this with a library of modules and subworkflows that can be integrated into any Nextflow pipeline, enabling research communities to progressively transition to nf-core best practices. We present a case study of nf-core adoption by six European research consortia, grouped under the EuroFAANG umbrella and dedicated to farmed animal genomics. We believe that the process outlined in this report can inspire many large consortia to seek harmonisation of their data analysis procedures.

bioinformatics↗

bioRxiv2023

A small-molecule TrkB ligand improves dendritic spine phenotypes and atypical behaviors in female Rett syndrome mice

Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in methyl-CpG-binding protein-2 (MECP2), encoding a transcriptional regulator of many genes, including brain-derived neurotrophic factor (Bdnf). BDNF mRNA and protein levels are lower in RTT autopsy brains and in multiple brain regions of Mecp2-deficient mice, and experimentally increasing BDNF levels improve atypical phenotypes in Mecp2 mutant mice. Due to the low blood-brain barrier permeability of BDNF itself, we tested the effects of a brain penetrant, small molecule ligand of its TrkB receptors. Applied in vitro, LM22A-4 increased dendritic spine density in pyramidal neurons in cultured hippocampal slices from postnatal day (P) 7 male Mecp2 knockout (KO) mice as much as recombinant BDNF, and both effects were prevented by the TrkB receptor inhibitors K-252a and ANA-12. Consistent with its partial agonist activity, LM22A-4 did not affect spine density in CA1 pyramidal neurons in slice cultures from male wildtype (WT) mice, where typical BDNF levels outcompete its binding to TrkB. To identify neurons of known genotypes in the mosaic brain of female Mecp2 heterozygous (HET) mice, we treated 4-6-month-old female MeCP2-GFP WT and HET mice with peripheral injections of LM22A-4 for 4 weeks. Surprisingly, mutant neurons lacking MeCP2-GFP showed dendritic spine volumes comparable to that in WT controls, while MeCP2-GFP-expressing neurons showed larger spines, similar to the phenotype we described in symptomatic male Mecp2 KO mice where all neurons lack MeCP2. Consistent with this non-cell-autonomous mechanism, a 4-week systemic treatment with LM22A-4 had an effect only in MeCP2-GFP-expressing neurons in female Mecp2 HET mice, bringing dendritic spine volumes down to WT control levels, and without affecting spines of MeCP2-GFP-lacking neurons. At the behavioral level, we found that female Mecp2 HET mice engaged in aggressive behaviors significantly more than WT controls, which were reduced to WT levels by a 4-week systemic treatment with LM22A-4. Altogether, these data revealed differences in dendritic spine size and altered behaviors in Mecp2 HET mice, in addition to provide support to the potential usefulness of BDNF-related therapeutic approaches such as the partial TrkB agonist LM22A-4.

neuroscience↗

bioRxiv2023

Scalable and efficient DNA sequencing analysis on different compute infrastructures aiding variant discovery

DNA variation analysis has become indispensable in many aspects of modern biomedicine, most prominently in the comparison of normal and tumor samples. Thousands of samples are collected in local sequencing efforts and public databases requiring highly scalable, portable, and automated workflows for streamlined processing. Here, we present nf-core/sarek 3, a well-established, comprehensive variant calling and annotation pipeline for germline and somatic samples. It is suitable for any genome with a known reference. We present a full rewrite of the original pipeline showing a significant reduction of storage requirements by using the CRAM format and runtime by increasing intra-sample parallelization. Both are leading to a 70% cost reduction in commercial clouds enabling users to do large-scale and cross-platform data analysis while keeping costs and CO2 emissions low. The code is available at https://nf-co.re/sarek.

bioinformatics↗

bioRxiv2023

Transcriptomics Reveals Tumorigenesis and Pathogen Response in Scombrid Puffy Snout Syndrome

Scombrids represent some of the most economically important fisheries globally. However, increased interest in creating aquaculture systems for these fish has also increased the risk for disease emergence. One such disease, Puffy Snout Syndrome (PSS), causes collagenous tissue growths on the face in numerous scombrid taxa. PSS has mainly been documented in captive-held fish populations and can lead to high mortality rates. Despite this, little is known about the causative agent(s) of PSS and the immune response they elicit. Therefore, we leveraged transcriptomic data of PSS symptomatic-captive, asymptomatic-captive, and healthy-wild Pacific Mackerel (Scomber japonicus) to evaluate the physiological characteristics of PSS infections and identify a potential mechanism of disease. Captive symptomatic and asymptomatic mackerel showed distinct gene expression patterns from their wild counterparts. Genes involved in tumorigenesis, immune response, and tissue remodeling were overexpressed in captive-held fish. WNT9 was the most overexpressed gene in captive groups, and the WNT signaling pathway itself showed a [~]3 fold increase in KEGG pathway enrichment analysis in captive animals. When captive fish were compared, asymptomatic fish showed lower expression of inflammation genes, but high expression of tumor suppressor genes compared to symptomatic-captive fish. Together, these host pathophysiological data and our past visual identification of RNA virus-like particles in afflicted tissues suggest that viral-mediated oncogenesis may be driving PSS in captive mackerel.

genomics↗

bioRxiv2023

Restoration of metabolic functional metrics from label-free, two-photon cervical tissue images using multiscale deep-learning-based denoising algorithms

Label-free, two-photon imaging captures morphological and functional metabolic tissue changes and enables enhanced understanding of numerous diseases. However, this modality suffers from low signal arising from limitations imposed by the maximum permissible dose of illumination and the need for rapid image acquisition to avoid motion artifacts. Recently, deep learning methods have been developed to facilitate the extraction of quantitative information from such images. Here, we employ deep neural architectures in the synthesis of a multiscale denoising algorithm optimized for restoring metrics of metabolic activity from low-SNR, two-photon images. Two-photon excited fluorescence (TPEF) images of reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) and flavoproteins (FAD) from freshly excised human cervical tissues are used. We assess the impact of the specific denoising model, loss function, data transformation, and training dataset on established metrics of image restoration when comparing denoised single frame images with corresponding six frame averages, considered as the ground truth. We further assess the restoration accuracy of six metrics of metabolic function from the denoised images relative to ground truth images. Using a novel algorithm based on deep denoising in the wavelet transform domain, we demonstrate optimal recovery of metabolic function metrics. Our results highlight the promise of denoising algorithms to recover diagnostically useful information from low SNR label-free two-photon images and their potential importance in the clinical translation of such imaging.

bioengineering↗

bioRxiv2023

The emergence and diversification of a zoonotic pathogen from within the microbiota of intensively farmed pigs

The expansion and intensification of livestock production is predicted to promote the emergence of pathogens. As pathogens sometimes jump between species this can affect the health of humans as well as livestock. Here we investigate how livestock microbiota can act as a source of these emerging pathogens through analysis of Streptococcus suis, a ubiquitous component of the respiratory microbiota of pigs that is also a major cause of disease on pig farms and an important zoonotic pathogen. Combining molecular dating, phylogeography and comparative genomic analyses of a large collection of isolates, we find that several pathogenic lineages of S. suis emerged in the 19th and 20th centuries, during an early period of growth in pig farming. These lineages have since spread between countries and continents, mirroring trade in live pigs. They are distinguished by the presence of three genomic islands with putative roles in metabolism and cell adhesion, and an ongoing reduction in genome size, which may reflect their recent shift to a more pathogenic ecology. Reconstructions of the evolutionary histories of these islands reveal constraints on pathogen emergence that could inform control strategies, with pathogenic lineages consistently emerging from one subpopulation of S. suis and acquiring genes through horizontal transfer from other pathogenic lineages. These results shed light on the capacity of the microbiota to rapidly evolve to exploit changes in their host population and suggest that the impact of changes in farming on the pathogenicity and zoonotic potential of S. suis is yet to be fully realised.

evolutionary biology↗

bioRxiv2023

Multi-frame biomechanical and relaxometry analysis during in vivo loading of the human knee by spiral dualMRI and compressed sensing

PurposeKnee cartilage experiences repetitive loading during physical activities, which is altered during the pathogenesis of diseases like osteoarthritis. Analyzing the biomechanics during motion provides a clear understanding of the dynamics of cartilage deformation, and may establish essential imaging biomarkers of early-stage disease. However, in vivo biomechanical analysis of cartilage during rapid motion is not well established. MethodsWe used spiral DENSE MRI on in vivo human tibiofemoral cartilage during cyclic varus loading (0.5 Hz) and employed compressed sensing on the k-space data. The applied compressive load was set for each participant at 0.5x body weight on the medial condyle. Relaxometry methods were measured on the cartilage before (T1{rho}, T2) and after (T1{rho}) varus load. ResultsDisplacement and strain maps showed a gradual shift of displacement and strain in time. Compressive strain was observed in the medial condyle cartilage and shear strain was roughly half of the compressive strain. Male participants had more displacement in the loading direction compared to females, and T1{rho} values did not change after cyclic varus load. Compressed sensing reduced the scanning time up to 25-40% when comparing the displacement maps and substantially lowered the noise levels. ConclusionThese results demonstrated the ease of which spiral DENSE MRI could be applied to clinical studies due to the shortened imaging time, while quantifying realistic cartilage deformations that occur through daily activities, and that could serve as biomarkers of early osteoarthritis.

bioengineering↗

bioRxiv2022

KATP Channel Prodrugs Reduce Inflammatory and Neuropathic Hypersensitivity, Morphine Induced Hypersensitivity, and Precipitated Withdrawal in Mice

Previous studies show ATP-sensitive potassium (KATP) channel openers can reduce hypersensitivity associated with chronic pain models in rodents, and reduce morphine tolerance. Many agonists of KATP channels are not soluble in physiologically relevant vehicles, requiring adaptation for clinical use. This study compared the antinociception activity of novel KATP channel targeting prodrugs, CKLP1, CKLP2, and CF3-CKLP. These prodrugs are activated by endogenous alkaline phosphatase enzymes present in the peripheral and central nervous systems. Analgesic capabilities of intrathecally injected prodrugs were tested in rodent models of spinal nerve ligation (SNL) and Complete Freunds Adjuvant (CFA) as models for neuropathic and inflammatory pain, respectively. CKLP1 and CKLP2 significantly increased mechanical paw withdrawal thresholds 1-2 hours after intrathecal administration in the SNL model, but all three prodrugs were able to attenuate hypersensitivity up to 7 days after CFA treatment. The reduction of opioid tolerance and opioid-induced hypersensitivity in mice treated chronically with morphine was significantly reduced in CKLP1 and CKLP2 treated animals. Prodrug cleavage was confirmed in mouse spinal cords using liquid chromatography. These studies may aid in the further development of KATP channel prodrugs for use in treatments of chronic pain, opioid tolerance, and withdrawal.

pharmacology and toxicology↗