RSS 1.0UMass Chan Student Research and Publications
ABOUT THIS COMMUNITY
UMass Chan Medical School has three graduate schools: the T.H. Chan School of Medicine, the Morningside Graduate School of Biomedical Sciences and the Tan Chingfen Graduate School of Nursing. The collections in these communities archive and share research from UMass Chan students of all three schools, including doctoral dissertations, master's theses, published journal articles, research projects, capstone presentations and conference materials.
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Divalent siRNAs are bioavailable in the lung and efficiently block SARS-CoV-2 infectionThe continuous evolution of SARS-CoV-2 variants complicates efforts to combat the ongoing pandemic, underscoring the need for a dynamic platform for the rapid development of pan-viral variant therapeutics. Oligonucleotide therapeutics are enhancing the treatment of numerous diseases with unprecedented potency, duration of effect, and safety. Through the systematic screening of hundreds of oligonucleotide sequences, we identified fully chemically stabilized siRNAs and ASOs that target regions of the SARS-CoV-2 genome conserved in all variants of concern, including delta and omicron. We successively evaluated candidates in cellular reporter assays, followed by viral inhibition in cell culture, with eventual testing of leads for in vivo antiviral activity in the lung. Previous attempts to deliver therapeutic oligonucleotides to the lung have met with only modest success. Here, we report the development of a platform for identifying and generating potent, chemically modified multimeric siRNAs bioavailable in the lung after local intranasal and intratracheal delivery. The optimized divalent siRNAs showed robust antiviral activity in human cells and mouse models of SARS-CoV-2 infection and represent a new paradigm for antiviral therapeutic development for current and future pandemics.
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Social Determinants, Blood Pressure Control, and Racial Inequities in Childbearing Age Women With Hypertension, 2001 to 2018Background Hypertension is an important modifiable risk factor of serious maternal morbidity and mortality. Social determinants of health (SDoH) influence hypertension outcomes and may contribute to racial and ethnic differences in hypertension control. Our objective was to assess SDoH and blood pressure (BP) control by race and ethnicity in US women of childbearing age with hypertension. Methods and Results We studied women (aged 20-50 years) with hypertension (systolic BP ≥140 mm Hg or diastolic BP ≥90 mm Hg or use of antihypertensive medication) in the National Health and Nutrition Examination Surveys 2001 to 2018. SDoH and BP control (systolic BP <140 mm Hg and diastolic BP <90 mm Hg) were examined by race and ethnicity (White race, Black race, Hispanic ethnicity, and Asian race). Using multivariable logistic regression, odds of uncontrolled BP by race and ethnicity were modeled, adjusting for SDoH, health factors, and modifiable health behaviors. Responses on hunger and affording food determined food insecurity status. Across women of childbearing age with hypertension (N=1293), 59.2% were White race, 23.4% were Black race, 15.8% were Hispanic ethnicity, and 1.7% were Asian race. More Hispanic and Black women experienced food insecurity than White women (32% and 25% versus 13%; both P<0.001). After SDoH, health factor, and modifiable health behavior adjustment, Black women maintained higher odds of uncontrolled BP than White women (odds ratio, 2.31 [95% CI, 1.08-4.92]), whereas Asian and Hispanic women showed no difference. Conclusions We identified racial inequities in uncontrolled BP and food insecurity among women of childbearing age with hypertension. Further exploration beyond the SDoH measured is needed to understand the inequity in hypertension control in Black women.
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Performance of Rapid Antigen Tests Based on Symptom Onset and Close Contact Exposure: A secondary analysis from the Test Us At Home prospective cohort study [preprint]Background: The performance of rapid antigen tests for SARS-CoV-2 (Ag-RDT) in temporal relation to symptom onset or exposure is unknown, as is the impact of vaccination on this relationship. Objective: To evaluate the performance of Ag-RDT compared with RT-PCR based on day after symptom onset or exposure in order to decide on 'when to test'. Design setting and participants: The Test Us at Home study was a longitudinal cohort study that enrolled participants over 2 years old across the United States between October 18, 2021 and February 4, 2022. All participants were asked to conduct Ag-RDT and RT-PCR testing every 48 hours over a 15-day period. Participants with one or more symptoms during the study period were included in the Day Post Symptom Onset (DPSO) analyses, while those who reported a COVID-19 exposure were included in the Day Post Exposure (DPE) analysis. Exposure: Participants were asked to self-report any symptoms or known exposures to SARS-CoV-2 every 48-hours, immediately prior to conducting Ag-RDT and RT-PCR testing. The first day a participant reported one or more symptoms was termed DPSO 0, and the day of exposure was DPE 0. Vaccination status was self-reported. Main outcome and measures: Results of Ag-RDT were self-reported (positive, negative, or invalid) and RT-PCR results were analyzed by a central laboratory. Percent positivity of SARS-CoV-2 and sensitivity of Ag-RDT and RT-PCR by DPSO and DPE were stratified by vaccination status and calculated with 95% confidence intervals. Results: A total of 7,361 participants enrolled in the study. Among them, 2,086 (28.3%) and 546 (7.4%) participants were eligible for the DPSO and DPE analyses, respectively. Unvaccinated participants were nearly twice as likely to test positive for SARS-CoV-2 than vaccinated participants in event of symptoms (PCR+: 27.6% vs 10.1%) or exposure (PCR+: 43.8% vs. 22.2%). The highest proportion of vaccinated and unvaccinated individuals tested positive on DPSO 2 and DPE 5-8. Performance of RT-PCR and Ag-RDT did not differ by vaccination status. Ag-RDT detected 78.0% (95% Confidence Interval: 72.56-82.61) of PCR-confirmed infections by DPSO 4. For exposed participants, Ag-RDT detected 84.9% (95% CI: 75.0-91.4) of PCR-confirmed infections by day five post-exposure (DPE 5). Conclusions and relevance: Performance of Ag-RDT and RT-PCR was highest on DPSO 0-2 and DPE 5 and did not differ by vaccination status. These data suggests that serial testing remains integral to enhancing the performance of Ag-RDT.
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Exploring the Phenomenon of MNNG Dose-Dependent Death PolypharmacologyRegulated cell death (RCD) is composed of several pathways that control cell fate. While each pathway is mechanistically distinct, these pathways have been shown to interact. Most of these interactions tend to be antagonistic, such that activation of one pathway blocks the subsequent activation of another pathway. This highlights that death pathways tend to be mutually exclusive. Thus, combining two cytotoxic drugs that activate different death pathways could result in less cell death than predicted, hampering therapeutic efficacy. As such, it is necessary to characterize which death pathways are activated by clinically relevant drugs, particularly for drug combination studies. However, studies of death pathway engagement are complicated by the fact that many drugs are capable of activating multiple RCD pathways. In order to improve annotations of RCD pathway activation by specific stimuli, we need to learn what features dictate which death pathway is activated. To study this phenomenon, we focused on characterizing RCD execution after treatment with methylnitronitrosoguanidine (MNNG), a DNA alkylating agent. MNNG is the canonical activator of parthanatos, an inflammatory form of RCD dependent on PARP-1 hyper-activation. We found that MNNG exhibits dose-dependent changes in death features, such as death onset time and death rate, indicative of a death mechanism change. As such we hypothesized that MNNG can induce multiple RCD pathways in a dose-dependent fashion. We found that this dose-dependent change in death features was generalizable to multiple cell lines. Moreover, we established that the phenotype was not due to PARP-trapping effects. Importantly, we uncovered that MNNG does induce a death mechanism switch. We found that MNNG is capable of inducing either parthanatos or apoptosis, depending on the dose. We also found evidence that the two death pathways induced by MNNG were mutually exclusive. And lastly, we established that the death mechanism switch was not due to altered mismatch repair (MMR). The information from this study could help to shed light on clinical outcomes from drug combination trials, specifically combinations with DNA damaging agents and PARP inhibitors.
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Changes in Stage at Presentation among Lung and Breast Cancer Patients During the COVID-19 PandemicBackground: The COVID-19 pandemic altered access to healthcare by decreasing number of patients able to receive preventative care and cancer screening. We hypothesized that given these changes in access to care, radiologic screening for breast and lung cancer would be decreased, and patients with these cancers would consequently present at later stages of their disease. Design: Retrospective cross-sectional study of 2017-September 2021 UMass Memorial Tumor Registry for adult breast and lung cancer patients. Changes in stage at presentation of breast and lung cancer during the COVID-19 pandemic were measured, defined as prior to and during COVID-19. Results: There were no statistically significant changes in the overall stage of presentation before or during the COVID-19 pandemic for either breast or lung cancer patients. Analysis of case presentation and stage during periods of COVID-19 surges that occurred over the time of this study compared to pre-pandemic data demonstrated a statistically significant decrease in overall presentation of breast cancer patients in the first surge, with no other statistically significant changes in breast cancer presentation. A non-statistically significant decrease in lung cancer presentations was seen during the initial surge of COVID-19. There was also a statistically significant increase in early-stage presentation of lung cancer during the second and third COVID-19 surges. Conclusions: In the two years after the COVID-19 pandemic we were not able to demonstrate stage migration at presentation of breast and lung cancer patients to later stages despite decreases in overall presentation during the initial two years of the COVID pandemic. An increase in early-stage lung cancer during the second and third surges is interesting and could be related to increased chest imaging for COVID pneumonia.
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Diagnoses Associated with Intellectual and Developmental Disabilities in Adult Decedents: A Secondary Analysis of Healthcare Cost and Utilization Project National Inpatient Sample (HCUP/NIS) DataPurpose: To identify primary and secondary diagnoses preceding death among adults with and without IDD who died during hospitalization. Specific Aims: 1) to describe the commonly reported base diagnostic related groups preceding death among decedents with and without IDD who died during hospitalization in 2019, 2) to determine which base-DRGs had a higher prevalence rate among adults with IDD than among adults without IDD, controlling for age, gender, race, urbanicity of person’s residence, US census division of hospital, and mean income of person’s zip code, and 3) to use the base-DRGs and ICD-10-CMs to examine the conditions of the Fatal Four/Five as conditions of concern preceding death in decedents with and without IDD. Framework: The NIMHD Minority Health and Health Disparities Research Framework. Design: A secondary data analysis using the 2019 Healthcare Cost and Utilization Project National (Nationwide) Inpatient Sample (HCUP-NIS). Results: Identified fourteen primary diagnoses at the time of death for decedents with IDD that are represented at a higher percentage than for decedents without IDD and have a significant odds ratio for IDD diagnosis. Conclusion: A new set of conditions is proposed to assist nurses in reducing preventable deaths in decedents with IDD. Dehydration, GI obstruction, respiratory infection, seizures, and sepsis, will be known as the IDD Concerning Conditions. Aspiration, constipation, and GERD, the IDD Contributing Conditions, are conditions that do not cause death in themselves but contribute to the development of at least one of the IDD Concerning Conditions, which do cause death.
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The choroid plexus links innate immunity to CSF dysregulation in hydrocephalusThe choroid plexus (ChP) is the blood-cerebrospinal fluid (CSF) barrier and the primary source of CSF. Acquired hydrocephalus, caused by brain infection or hemorrhage, lacks drug treatments due to obscure pathobiology. Our integrated, multi-omic investigation of post-infectious hydrocephalus (PIH) and post-hemorrhagic hydrocephalus (PHH) models revealed that lipopolysaccharide and blood breakdown products trigger highly similar TLR4-dependent immune responses at the ChP-CSF interface. The resulting CSF "cytokine storm", elicited from peripherally derived and border-associated ChP macrophages, causes increased CSF production from ChP epithelial cells via phospho-activation of the TNF-receptor-associated kinase SPAK, which serves as a regulatory scaffold of a multi-ion transporter protein complex. Genetic or pharmacological immunomodulation prevents PIH and PHH by antagonizing SPAK-dependent CSF hypersecretion. These results reveal the ChP as a dynamic, cellularly heterogeneous tissue with highly regulated immune-secretory capacity, expand our understanding of ChP immune-epithelial cell cross talk, and reframe PIH and PHH as related neuroimmune disorders vulnerable to small molecule pharmacotherapy.
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Modulation of neuronal excitability by binge alcohol drinkingDrug use poses a serious threat to health systems throughout the world. The number of consumers rises every year being alcohol the drug of abuse most consumed causing 3 million deaths (5.3% of all deaths) worldwide and 132.6 million disability-adjusted life years. In this review, we present an up-to-date summary about what is known regarding the global impact of binge alcohol drinking on brains and how it affects the development of cognitive functions, as well as the various preclinical models used to probe its effects on the neurobiology of the brain. This will be followed by a detailed report on the state of our current knowledge of the molecular and cellular mechanisms underlying the effects of binge drinking on neuronal excitability and synaptic plasticity, with an emphasis on brain regions of the meso-cortico limbic neurocircuitry.
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The Genomics of Canine Behavior and its Comparative Relevance to Human Neuropsychiatric ConditionsMounting genomic evidence suggests that biological contributions to psychiatric disorder susceptibility are genetically complex, environmentally mediated, and highly comorbid. By paralleling human initiatives, I propose that comparative genomics in the domestic dog offers informational and translational utility to investigations of such complex conditions. Dogs present problematic behaviors with ostensible similarity to human disorders, such as separation anxiety and compulsive behaviors. As behavior played a major role in dog evolution, canine genomes may be enriched for common genetic variants underlying many behaviors. Breeds represent a distillation of diversity in appearance and behavior, but there has been limited success in linking the latter to genes using only pedigreed dogs. The genomes of “mutts” present a natural experiment in genome-wide admixture, which I leverage to map high-dimensional phenotypes across thousands of pet dogs. While I find that most behavioral differences are heritable, especially functional behaviors characteristic of major lineages, I also show that breed alone is an unreliable and confounded predictor of dog behavior. By intersecting genomic studies in people and dogs, this work supplies a roadmap for discerning and ranking cross-species relevance for a wide array of canine and human phenotypes, including psychiatric conditions.
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Staying HomeIn this narrative medicine essay, a third-year medical student who chose hospice for her infant with a life-limiting condition considers her uncertainty about whether the family may have extended their brief time together through medical intervention.
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The Role of Chromatin Architecture in Motor Neurons in Maturation and Amyotrophic Lateral SclerosisAmyotrophic lateral sclerosis (ALS) is a progressive and lethal neurodegenerative disorder that is caused by the selective degeneration of upper and lower motor neurons (MNs) in the central nervous system. The causes of ALS are poorly understood and likely to be heterogenous; a compelling approach to understand ALS has been to investigate the 10% of cases with a positive familial history. More than 40 genes have been associated with familial cases. The most common ALS causing gene, C9orf72, has a unique hexanucleotide repeat expansion (HRE) located in the first intron. The hallmark of the C9orf72 pathology includes RNA foci accumulation and translation, and aggregates of repeat-associated dipeptides (DPR) in the nucleus and cell body. In recent years, using 3C-based chromosome conformation technologies, chromatin folding of various cell types, such as fibroblasts, embryonic stem cells (ESC) and neurons, have revealed crucial information to understand 3D folding mechanisms and architectural structures in the nucleus. I performed Hi-C 2.0 and RNA-seq to investigate the three-dimensional genome architectures and transcriptome profiles in three different cell types generated from healthy and ALS individuals with C9orf72 mutation through reprogramming fibroblasts into induced pluripotent stem cells (IPSCs), IPSC differentiation into MNs, and maturation of MNs. Firstly, I analyzed healthy cell types to understand how reprogramming, neural differentiation, and long-term maturation alter genome folding. Secondly, I investigated whether chromatin folding is affected in fibroblasts, IPSCs and MNs of ALS patients with C9orf72 HRE mutation by using the same strategy. This work demonstrated that MNs require long term maturation to establish proper transcriptome and genome folding. Moreover, C9orf72 HRE mutation does not cause any alteration in fibroblast and IPSC lines, however, partial alterations in large scale genome folding were observed in motor neurons.
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Large-scale organoid study suggests effects of trisomy 21 on early fetal neurodevelopment are more subtle than variability between isogenic lines and experimentsThis study examines cortical organoids generated from a panel of isogenic trisomic and disomic iPSC lines (subclones) as a model of early fetal brain development in Down syndrome (DS). An initial experiment comparing organoids from one trisomic and one disomic line showed many genome-wide transcriptomic differences and modest differences in cell-type proportions, suggesting there may be a neurodevelopmental phenotype that is due to trisomy of chr21. To better control for multiple sources of variation, we undertook a highly robust study of ∼1,200 organoids using an expanded panel of six all-isogenic lines, three disomic, and three trisomic. The power of this experimental design was indicated by strong detection of the ∼1.5-fold difference in chr21 genes. However, the numerous expression differences in non-chr21 genes seen in the smaller experiment fell away, and the differences in cell-type representation between lines did not correlate with trisomy 21. Results suggest that the initial smaller experiment picked up differences between small organoid samples and individual isogenic lines, which "averaged out" in the larger panel of isogenic lines. Our results indicate that even when organoid and batch variability are better controlled for, variation between isogenic cell lines (even subclones) may obscure, or be conflated with, subtle neurodevelopmental phenotypes that may be present in ∼2nd trimester DS brain development. Interestingly, despite this variability between organoid batches and lines, and the "fetal stage" of these organoids, an increase in secreted Aβ40 peptide levels-an Alzheimer-related cellular phenotype-was more strongly associated with trisomy 21 status than were neurodevelopmental shifts in cell-type composition.
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Current and upcoming radionuclide therapies in the direction of precision oncology: A narrative reviewAs new molecular tracers are identified to target specific receptors, tissue, and tumor types, opportunities arise for the development of both diagnostic tracers and their therapeutic counterparts, termed "theranostics." While diagnostic tracers utilize positron emitters or gamma-emitting radionuclides, their theranostic counterparts are typically bound to beta and alpha emitters, which can deliver specific and localized radiation to targets with minimal collateral damage to uninvolved surrounding structures. This is an exciting time in molecular imaging and therapy and a step towards personalized and precise medicine in which patients who were either without treatment options or not candidates for other therapies now have expanded options, with tangible data showing improved outcomes. This manuscript explores the current state of theranostics, providing background, treatment specifics, and toxicities, and discusses future potential trends.
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Neurexins in serotonergic neurons regulate neuronal survival, serotonin transmission, and complex mouse behaviorsExtensive serotonin (5-hydroxytryptamine, 5-HT) innervation throughout the brain corroborates 5-HT's modulatory role in numerous cognitive activities. Volume transmission is the major mode for 5-HT transmission but mechanisms underlying 5-HT signaling are still largely unknown. Abnormal brain 5-HT levels and function have been implicated in autism spectrum disorder (ASD). Neurexin (Nrxn) genes encode presynaptic cell adhesion molecules important for the regulation of synaptic neurotransmitter release, notably glutamatergic and GABAergic transmission. Mutations in Nrxn genes are associated with neurodevelopmental disorders including ASD. However, the role of Nrxn genes in the 5-HT system is poorly understood. Here, we generated a mouse model with all three Nrxn genes disrupted specifically in 5-HT neurons to study how Nrxns affect 5-HT transmission. Loss of Nrxns in 5-HT neurons reduced the number of serotonin neurons in the early postnatal stage, impaired 5-HT release, and decreased 5-HT release sites and serotonin transporter expression. Furthermore, 5-HT neuron-specific Nrxn knockout reduced sociability and increased depressive-like behavior. Our results highlight functional roles for Nrxns in 5-HT neurotransmission, 5-HT neuron survival, and the execution of complex behaviors.
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Investigating the role of mutational interdependencies on viral protein function and the evolution of drug resistanceInteraction of mutations is ubiquitous in understanding protein fitness landscapes. Fitness landscapes are critical in understanding protein evolution and drug resistance. I aim to elucidate functional consequences of mutations in viral proteins. Retroviral proteases cleave highly diverse substrates, for example, HIV-1 protease (PR) cleaves dramatically different cleavage sites, making it a challenging and interesting system to investigate epistasis. Epistasis also plays an important role in shaping the emergence and evolution of drug resistance, for example in Oseltamivir resistance in Influenza A virus (IAV). To systematically investigate interaction of mutations in important proteins of RNA viruses, we used a mutational scanning approach, EMPIRIC, to investigate the fitness landscape of cleavage sites of HIV-1 PR. We observed that the cleavage sites had higher preferences for hydrophobic and aromatic amino acids. We also observed that negatively charged amino acids are preferred at positions distal to the scissile bond, where these positions are not involved in binding in the PR active site. Studying the fitness landscapes revealed that biophysical features and context-dependencies both mediate cutting of the cleavage sites. However, in-depth analysis of long-range and short-range contextuality would provide further insights on functional determinants of PR cleavage. I also explored the interaction of mutations in the neuraminidase (NA) of influenza A virus in response to inhibitor oseltamivir and identified positive epistasis between drug resistant mutation and a permissive mutation. Our data revealed the potential of epistasis in the evolution of drug resistance in circulating viruses. In summary, these studies provide a framework to examine evolutionary constraints and biochemical mechanisms of viral proteins that can contribute to the evolution of drug resistance.
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A Transcriptional Cofactor Regulatory Network in the C. Elegans IntestineTranscription is fundamental to growth, development, and homeostasis of all known organisms. It is imperative that genes are expressed correctly, both in time and in specific tissues. Proper spatiotemporal gene expression is controlled by a combination of regulatory factors: DNA binding transcription factors and transcriptional cofactors and chromatin modifiers. Chromatin modifiers are responsible for rearranging DNA structure to affect local transcription. Other transcriptional cofactors work by binding transcription factors and regulating RNA polymerase activity to regulate transcription. While transcription factors have established roles in activating and repressing specific genes, chromatin modifiers and cofactors also act specifically. In multicellular organisms each tissue has its own unique transcriptional program (gene regulatory network) driven by combinations of transcriptional regulators governing the expression of genes necessary for development and homeostasis. To characterize the transcriptional cofactor gene regulatory network, I performed a screen in the Caenorhabditis elegans intestine. Here, the effects of chromatin modifiers and cofactors on nineteen promoters in the C. elegans intestine are assessed using RNAi knockdowns and a set of transcriptional fluorescent reporters. I find no cofactors are universally required to activate all nineteen transcriptional reporters, but certain cofactor complexes seem to work cooperatively to activate or repress the transcription from specific promoters. I also found that transcription from one promoter, that of acdh-1, uses separate transcription factors but common cofactors depending on the biological perturbation activating its transcription. This study demonstrates that cofactors do not act identically at all promoters, similar to the activities of transcription factors.
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Interactions between FUS and the C-terminal Domain of Nup62 are Sufficient for their Co-phase Separation into Amorphous AssembliesDeficient nucleocytoplasmic transport is emerging as a pathogenic feature of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), including in ALS caused by mutations in Fused in Sarcoma (FUS). Recently, both wild-type and ALS-linked mutant FUS were shown to directly interact with the phenylalanine-glycine (FG)-rich nucleoporin 62 (Nup62) protein, where FUS WT/ Nup62 interactions were enriched within the nucleus but ALS-linked mutant FUS/ Nup62 interactions were enriched within the cytoplasm of cells. Nup62 is a central channel Nup that has a prominent role in forming the selectivity filter within the nuclear pore complex and in regulating effective nucleocytoplasmic transport. Under conditions where FUS phase separates into liquid droplets in vitro, the addition of Nup62 caused the synergistic formation of amorphous assemblies containing both FUS and Nup62. Here, we examined the molecular determinants of this process using recombinant FUS and Nup62 proteins and biochemical approaches. We demonstrate that the structured C-terminal domain of Nup62 containing an alpha-helical coiled-coil region plays a dominant role in binding FUS and is sufficient for inducing the formation of FUS/Nup62 amorphous assemblies. In contrast, the natively unstructured, F/G repeat-rich N-terminal domain of Nup62 modestly contributed to FUS/Nup62 phase separation behavior. Expression of individual Nup62 domain constructs in human cells confirmed that the Nup62 C-terminal domain is essential for localization of the protein to the nuclear envelope. Our results raise the possibility that interactions between FUS and the C-terminal domain of Nup62 can influence the function of Nup62 under physiological and/or pathological conditions.
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The Role of Wearable Technology in Measuring and Supporting Patient Outcomes Following Total Joint Replacement: Review of the LiteratureBackground: The incidence rate of total joint replacement (TJR) continues to increase due to the aging population and the surgery that is very successful in providing pain relief to and improving function among patients with advanced knee or hip arthritis. Improving patient outcomes and patient satisfaction after TJR remain important goals. Wearable technologies provide a novel way to capture patient function and activity data and supplement clinical measures and patient-reported outcome measures in order to better understand patient outcomes after TJR. Objective: We examined the current literature to evaluate the potential role of wearable devices and compare them with existing methods for monitoring and improving patient rehabilitation and outcomes following TJR. Methods: We performed a literature search by using the research databases supported by the University of Massachusetts Chan Medical School's Lamar Soutter Library, including PubMed and Scopus, supplemented with the Google Scholar search engine. A specific search strategy was used to identify articles discussing the use of wearable devices in measuring and affecting postoperative outcomes of patients who have undergone TJR. Selected papers were organized into a spreadsheet and categorized for our qualitative literature review to assess how wearable data correlated with clinical measures and patient-reported outcome measures. Results: A total of 9 papers were selected. The literature showed the impact of wearable devices on evaluating and improving postoperative functional outcomes. Wearable-collected data could be used to predict postoperative clinical measures, such as range of motion and Timed Up and Go times. When predicting patient-reported outcomes, specifically Hip Disability and Osteoarthritis Outcome Scores/Knee Injury and Osteoarthritis Outcome Scores and Veterans RAND 12-Item Health Survey scores, strong associations were found between changes in sensor-collected data and changes in patient-reported outcomes over time. Further, the step counts of patients who received feedback from a wearable improved over time when compared to those of patients who did not receive feedback. Conclusions: These findings suggest that wearable technology has the potential to remotely measure and improve postoperative orthopedic patient outcomes. We anticipate that this review will facilitate further investigation into whether wearable devices are viable tools for guiding the clinical management of TJR rehabilitation.
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Presynaptic Gq-coupled receptors drive biphasic dopamine transporter trafficking that modulates dopamine clearance and motor functionExtracellular dopamine (DA) levels are constrained by the presynaptic DA transporter (DAT), a major psychostimulant target. Despite its necessity for DA neurotransmission, DAT regulation in situ is poorly understood, and it is unknown whether regulated DAT trafficking impacts dopaminergic signaling and/or behaviors. Leveraging chemogenetics and conditional gene silencing, we found that activating presynaptic Gq-coupled receptors, either hM3Dq or mGlu5, drove rapid biphasic DAT membrane trafficking in ex vivo striatal slices, with region-specific differences between ventral and dorsal striata. DAT insertion required D2 DA autoreceptors and intact retromer, whereas DAT retrieval required PKC activation and Rit2. Ex vivo voltammetric studies revealed that DAT trafficking impacts DA clearance. Furthermore, dopaminergic mGlu5 silencing elevated DAT surface expression and abolished motor learning, which was rescued by inhibiting DAT with a subthreshold CE-158 dose. We discovered that presynaptic DAT trafficking is complex, multimodal, and region specific, and for the first time, we identified cell autonomous mechanisms that govern presynaptic DAT tone. Importantly, the findings are consistent with a role for regulated DAT trafficking in DA clearance and motor function.
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Characterization of Sec3 and its conformation within the exocyst complexFor eukaryotic cells to function properly, vesicles need to be targeted to proper partner membranes. Exocyst is a heteroctameric complex that acts as a platform for a suite of regulatory proteins to guide vesicle targeting and fusion. A key interaction is with SNAREs, which provide the mechanical force to fuse membranes. Several exocyst components have been implicated in SNARE regulation, but only the Sec3 subunit has been shown to play a role in driving SNARE assembly. The N-terminal region of Sec3 (Sec3N) is highly flexible and partially unstructured which has made characterizing Sec3N challenging, especially its position relative to the rest of the exocyst complex. The extent to which the mostly unstructured nature of Sec3N plays a role in exocyst function, particularly SNARE-binding, is unknown. Using a combination of computational modeling, biochemical assays, and crosslinking mass spectrometry (XLMS), I modeled the secondary structure of Sec3N and characterized its orientation in relation to exocyst. I also identified multiple phosphorylation sites on Sec3N that were not previously known in the literature. I hypothesized that phosphorylation of Sec3 induces a conformational change which plays an inhibitory role in its function. By showing that Sec3 structure and function can be regulated by phosphorylation, I pinpointed a means by which exocyst can be modulated in a temporal and spatial manner. These findings will help guide future studies in which the specific kinases and phosphatases that play a role in exocytic function will be elucidated. Furthermore, these findings will provide insight into future structural studies on Sec3N and how its conformation plays a role in SNARE complex assembly.
