MEDICA@MUSC (Medical University of South Carolina)
Not a member yet
1558 research outputs found
Sort by
Antibiotic-Induced Gut Dysbiosis During Adolescence Dysregulates Metabolism and Skeletal Maturation
No full textProblem: Antibiotic-induced shifts in the commensal gut microbiota can induce a dysbiotic relationship between the host and microbes. Antibiotic administration during critical windows of development and long-term antibiotic treatment impairs the gut microbiota’s ability to recover to a stable state. Systemic tetracyclines (minocycline, doxycycline) are prescribed for extended durations to treat adolescent acne. However, the impact of tetracyclines on metabolism, adiposity, and skeletal maturation is unclear.
Approach: Sex-matched specific-pathogen-free and germ-free mice were administered a clinically relevant minocycline or doxycycline or vehicle-control from age 6-12 weeks. Mice were euthanized at ages 12 and 18 weeks to determine immediate and sustained antibiotic treatment effects. 16S rDNA sequencing was performed in colonic contents. Skeletal properties and adiposity were evaluated by micro-CT and biomechanical analysis. Osteoblastogenesis/osteoclastogenesis were evaluated by histomorphometry and serum ELISA. qRT-PCR/RNA-seq/nCounter analysis were performed in ileums and livers. Serum bile acids were assessed by mass spectrometry. Osteoblasts from wild-type and FXR-null mice were stimulated with circulating therapeutic levels of minocycline or the circulating bile acid profile detected in specific-pathogen-free mice.
Results: Minocycline, but not doxycycline, impaired bone mass accrual and fracture resistance which was attributed to suppressed osteoblast function. Minocycline did not alter the skeletal phenotype in germ-free mice, which implies that minocycline effects on the skeleton are dependent on the microbiota. Minocycline dysregulated the intestinal FXR-FGF15 axis in specific-pathogen-free mice. The intestinal FXR-FGF15 axis is a gut-liver endocrine axis that supports bile acid homeostasis and host metabolism. Minocycline induced changes in the abundance of genera critical for bile acid metabolism. Minocycline decreased ileum FGF15, upregulated hepatic Cyp7a1, and increased circulating conjugated bile acids. Stimulating primary osteoblasts with the serum bile acid profile from minocycline-treated specific-pathogen-free mice recapitulated the suppressed osteogeneic phenotype found in vivo, which was mediated through attenuated FXR-signaling. Systemic tetracyclines dysregulated liver metabolism and increased adiposity in specific-pathogen-free mice.
Conclusion: This preclinical research reveals that prolonged antibiotic exposure during adolescence suppresses skeletal maturation and promotes adiposity. Further, this body of work introduces gut-liver bile acid metabolism as a candidate regulator of antibiotic-induced gut dysbiosis effects on the skeleton and adiposity
Utilizing Mass Spectrometry Imaging to Correlate N-Glycosylation of Hepatocellular Carcinoma with Tumor Subtypes for Biomarker Discovery
Get PDFHepatocellular carcinoma (HCC) is a leading cause of cancer deaths globally and is a growing clinical problem with poor survival outcomes beyond early-stage disease. Surveillance for HCC has primarily relied on ultrasound and serum α-fetoprotein (AFP), but combined they only have a sensitivity of 63% for early-stage HCC tumors, suggesting a need for improved diagnostic strategies. Alterations to N-glycan expression are relevant to the progression of cancer, and there a multitude of N-glycan-based cancer biomarkers that have been identified with sensitivity for various cancer types including HCC. Spatial HCC tissue profiling of N-linked glycosylation by matrix-assisted laser desorption ionization imaging mass spectrometry (MALDI-IMS) serves as a new method to evaluate tumor-correlated N-glycosylation and thereby identify potential HCC biomarkers. Previous work has identified significant changes in the N-linked glycosylation of HCC tumors, but has not accounted for the heterogeneous genetic and molecular nature of HCC, which has led to inadequate sensitivity of N-glycan biomarkers. Therefore, we hypothesized that the incorporation of genetic/molecular information into N-glycan-based biomarker development would result in improved sensitivity for HCC. To determine the correlation between HCC-specific N-glycosylation and genetic/molecular tumor features, we profiled HCC tissue samples with MALDI-IMS and correlated the spatial N-glycosylation with a widely used HCC molecular classification that utilizes histological, genetic, and clinical tumor features (Hoshida subtypes). MALDI-IMS data displayed trends that could approximately distinguish between subtypes, with Subtype 1 demonstrating significantly dysregulated N-glycosylation compared to Subtypes 2 and 3, particularly in regard to fucosylation. In order to further the clinical relevance of subtype-dependent N-glycosylation, we analyzed patient-matching HCC tumor tissue, background liver tissue and serum samples through MALDI-IMS. Results showed a N-glycan based model capable of differentiating tumor tissue from background liver tissue with an AUC of 0.9842. When analyzing the associated serum, 24.7% of detected N-glycans were significantly positively correlated between tumor tissue and serum, suggesting that N-glycosylation trends translate from tissue to serum. Additionally, a serum N-glycan-based model was capable of distinguishing Subtype 1/Subtype 2 tumors from Subtype 3 tumors with an AUC of 0.881. Through the utilization of MALDI-IMS, subtype-dependent N-glycosylation trends were identified in both tissue and serum, which can significantly further the development of HCC biomarkers for clinical application
Identifying the Temporal N-linked Glycosylation Changes During Liver Disease Progression: from Liver Injury to End-stage Liver Disease
Get PDFThe high mortality rates of liver diseases and primary liver cancers can be attributed to the lack of screening and diagnostic strategies currently available for early detection. Non-alcoholic fatty liver disease (NAFLD) is an early stage of liver disease known to progress to a variety of pre-malignant and malignant conditions, like advanced fibrosis, cirrhosis, hepatocellular carcinoma (HCC), and cholangiocarcinoma (CCA). Based on the wide variety of diseases that NAFLD can progress to, strategies to understand and detect the progression of NAFLD are of great value. Core fucosylation of N-linked glycans has been demonstrated to be useful for the clinical diagnosis of HCC, through the use of the serum biomarker AFP-L3. However, the role of core fucosylation, catalyzed by Fucosyltransferase (Fut8) in HCC or any liver diseases is still not fully understood. Here, we utilized human samples and an in vivo approach to characterize the origin, temporal changes, and biomarker use of modifications in N-liked glycosylation by MALDI-IMS (Matrix-assisted laser desorption/ionization imaging mass spectrometry) in NAFLD and its progressive form. Spatial N-glycan analysis in NAFLD mouse and human liver biopsies revealed that fucosylated N-linked glycan modifications correlate with areas of fibrosis. Next, we use an in vivo liver disease induction time point study to elucidate that bisected fucosylated N-glycan modifications can be observed even before histopathological alterations are significant and are consistently altered from fatty liver disease, up to stages with liver dysplasia. For CCA, we took a biomarker discovery approach in tissue and serum and identified that bisected fucosylated structures distinguished CCA patients from those with any other type of liver disease and normal tissue, better than the gold-standard serum biomarker for CCA, CA-19-9. Finally, we generated the first liver specific Fut8 mouse model to further study the impact of core fucosylation in these liver diseases. Overall, the studies presented in this dissertation, elucidate the value of N-glycosylation for biomarker strategies for early detection and different stages of progressive liver disease. Importantly, these studies set the field for a mechanistic approach to one of the most characterized N-glycan modifications in liver cancer by the generation of a tissue-specific mouse model
Role of Macrophages in Regression of Myocardial Fibrosis Following Alleviation of Left Ventricular Pressure Overload
Get PDFAntecedent conditions that affect the heart, such as aortic stenosis (AS), can develop into left ventricular pressure overload (LVPO). LVPO is associated with increased myocardial interstitial fibrosis, specifically fibrillar collagen, that leads to increased myocardial stiffness. Patients undergoing surgical aortic valve replacement (SAVR) to correct AS demonstrate significant but incomplete regression of fibrosis. Although current therapies normalize hemodynamic load, treatments that regress collagen content within the myocardium remain a critical need. To elucidate cellular mechanisms of this persistent fibrosis in LVPO, we utilized a transverse aortic constriction (TAC) and removal of the constriction (unTAC) murine model. Outputs were assessed for: Control, 2wk TAC, 4wk TAC, 4wk TAC+2wk unTAC, 4wk TAC+4wk unTAC, and 4wk TAC+6wk unTAC. Collagen volume fraction (CVF), collagen hybridizing peptide (CHP), and macrophage abundance were assessed by immunohistochemistry. Macrophage phenotype was assessed by flow cytometry and rt-qPCR. Cytokine profiles and enzymes implicated in collagen turnover were determined by immunoassay and immunoblots. To determine the role of macrophages in collagen turnover following alleviation of LVPO, macrophages were depleted with clodronate liposomes at time of unTAC surgery and endpoints were measured at 2wk unTAC. CHP reactivity was significantly increased at 2wk unTAC compared to other time points. A significant reduction in CVF was observed at 4wk unTAC compared to 4wk TAC and 2wk unTAC although it remained increased compared to control levels. A defined temporal pattern in myocardial macrophage cell count was observed: increased in 2wk TAC that decreased at 4wk TAC followed by a further increase at 2wk unTAC and then decreased at 4wk and 6wk unTAC. Macrophage counts at all time points remained higher than control. Macrophage area was significantly increased at 2wk unTAC compared to all other time points. Profibrotic macrophage markers, F4/80+CD206+, F4/80+CD163+, and Ly6ClowF4/80high, were increased in TAC compared to unTAC. Depletion of macrophages reduced CHP reactivity and decreased Cathepsin K and proMMP2 levels. In conclusion, normalization of hemodynamic load leads to regression of cardiomyocyte hypertrophy but does not result in complete regression of myocardial fibrosis. Temporal changes in macrophage cell count and phenotype play a critical role in the development of fibrosis during TAC and the partial, but incomplete regression of fibrosis in unTAC
Increased Physician Literacy as an Intervention to Improve Value-Based Care and Reduce Cost in the Surgical Setting
Get PDFThe primary goal of this scoping review was to identify studies where an intervention of education and awareness of surgical supply costs with surgeons was employed as a possible stimulus for healthcare organization cost reduction in the surgical/procedural service space.
Surgical procedures are performed on approximately 25 percent of all inpatient hospital admissions. In 2018 that equated to 14.4 million surgical procedures and 912 billion dollars annually by the year 2025.
Research aims were; is there an existing gap in knowledge of the cost of medical supplies for surgeons, does educating surgeons who make decisions regarding the selection of medical supplies/devices using the primary data points of price per procedure result in cost control and lead to lower costs of care and is there enough evidence to support a specific clinician education program for cost reduction?
100% of the ten studies included in this review articulate the foundational problem of surgeons not having knowledge of the cost of the supplies that they utilize every day in the operating room and an objective to educate or increase cost awareness for these decision makers. Interventions savings generated by procedure range from 4.1% to 54%. When savings were averaged for each study across all case types; the study’s average cost saving ranged from 5.9% to 40%. Averaging identified cost savings across the two primary classifications of intervention yielded a 20% cost savings associated with education being provided through meetings and/or cost sharing. Surgical Receipt and Report programs leveraged a 9.6% savings. Meetings and Cost Sharing education are documented as easier to launch then other initiatives. Surgical Receipt and Report programs are often difficult to operationalize depending on a health system’s clinical documentation method and platform employed in the surgical setting
Cost Effectiveness of Buprenorphine when Used Long Term versus Short Term Use
Get PDFSince 1999, nearly 841,000 people have died from a drug overdose (CDC, 2022), and substance use disorder (SUD) continues to be a crisis that faces communities across the country. As the crisis continues across communities, the need for medication-assisted opioid use disorder (MOUD) therapy continues to surge.
This was a retrospective analysis of archival data from large national data sources. We constructed well-matched cohorts of patients with short and long-term use of MOUD using propensity score matching of 3 months of baseline data. To measure the cost effectiveness of short-term buprenorphine use verse long-term buprenorphine use
Activity Dynamics of the Nucleus Accumbens Neurons During Natural and Drug Reward Seeking
Get PDFThe nucleus accumbens core (NAc) represents a major neural substrate of reward encoding that has been found to play a role in differentially regulating natural and drug rewards, including cocaine. Its constituent D1- and D2- receptor expressing medium spiny neurons (MSN) are alternatively hypothesized to have either opposing effects on reward seeking or a shared role in forming encoding “ensembles” – a sparsely activated population of neurons that encode reward associations- that coordinate behavioral responding to rewards and cues predicting reward availability. Previous methods used to study these neuronal populations failed to temporal quantify the cell-type specific activity in reward seeking tasks.
To conjoin the functional dichotomy and ensemble hypotheses, we leveraged the use of single-cell calcium imaging of D1- and D2-MSN in freely behaving mice during active sucrose and cocaine self-administration, cued seeking and extinction. In the first part of the dissertation, we show that reinforced cocaine and sucrose seeking are associated with the recruitment of time-locked excitatory and inhibitory ensembles from both cell types. The seeking ensemble of excited D1-MSN showed high stability within- and across- multiple sessions for both reward types, while the stable recruitment of D2-MSN was only identified with cocaine self-administration. The balance between stability and dynamicity of D1- and D2-MSN ensembles, respectively, may be a consequential aspect of how NAcore encodes natural reward seeking.
The second part of my dissertation aimed to determine if D1- and D2-MSN differentially encode cocaine seeking and sucrose seeking behavior in cued non-reinforced seeking tasks. Previous reports have shown drug-specific synaptic potentiation of the nucleus accumbens core associated with cued seeking after abstinence that is not seen with natural reward seeking. We show that D1-MSN, but not D2-MSN, were found to differentially encode cocaine seeking over sucrose seeking through stable and consistently recruited excitatory ensembles during cued seeking after forced abstinence or extinction training. Interestingly, I show that different ensembles are recruited during cued seeking before and after extinction. Together, my data reveal a unique neuronal signature of D1-MSN associated with relapse to cocaine
Waring Library Society Newsletter, Fall 2023
Get PDFIn the Fall 2023 issue of the Waring Library Society Newsletter, Waring Library Society President Dr. Jacob Steere-Williams discusses R.A. Kinloch’s contributions to the 19th century surgical revolution; JoAnn Zeise gives a welcome message at the beginning of her tenure as the Waring Historical Library’s new curator; Anna Marie Schuldt shares the recently released online exhibits ahead of MUSC’s bicentennial; she additionally reviews the successful events held by the Waring in Fall 2023; and guest writer Lahnice Hollister shares a story of Moses Camplin’s struggle to practice medicine in Charleston as a Black practitioner post-Civil War.https://medica-musc.researchcommons.org/wls-newsletters/1006/thumbnail.jp
Targeted Multimodal Approaches to Treat Aggressive Breast Cancers via Therapeutic Inhibition of Key Vulnerabilities
No full textBreast cancer is the most commonly diagnosed cancer and the second leading cause of cancer death in women worldwide. It is a heterogeneous disease, and clinically classified into three subtypes: estrogen receptor-positive (ER+), HER2-positive (HER2+) and triple negative breast cancer (TNBC). Depending on the subtype, breast cancer patients can be treated with different targeted therapy and chemotherapy agents. However, a large fraction of patients exhibits disease recurrence, greatly reducing the clinical outcome. Here, three novel molecular targets that are overexpressed and associated with worse disease progression and therapy resistance in the most aggressive subtypes/subpopulations of breast cancer patients have been identified. Firstly, in ER+ breast cancer, constituting around 70% of all cases, it was found that the standard-of-care (SOC) therapies (e.g., tamoxifen, fulvestrant or palbociclib) used in clinics downregulates phosphodiesterase 4D (PDE4D), a novel ER target gene, leading to BRCAness, activation of cAMP/ROS/DNA damage axis and cell death. On the other hand, PDE4D was shown to be overexpressed via EGFR-mediated c-Jun activation in SOC resistant tumors, associated with worse clinical outcome, and its therapeutic targeting in combination with SOC therapies in drug-resistant settings reinstates BRCAness, leading to drug sensitization. Secondly, in TNBCs, constituting around 10-15% of all cases, remodeling of tumor microenvironment via overexpression of the lysyl oxidase (LOX) enzyme was shown to drive chemoresistance. Targeting LOX leads to de-crosslinking of the extracellular matrix (ECM), increases drug penetration, and inhibits FAK-Src-mediated survival signaling, culminating in chemosensitization. Thirdly, the transforming acidic coiled-coil-containing protein 3 (TACC3) was identified as a novel centrosome amplification (CA)-directed dependency, driving cell growth by forming distinct functional interactomes with KIFC1 in mitosis or MBD2/HDAC2 complex in interphase during cell cycle progression. Targeting the spatiotemporal functions of TACC3 inhibits the growth of highly aggressive breast cancer tumors with CA. Overall, the work presented here contributes to a better understanding of the progression of highly aggressive breast cancers and provides novel and clinically translatable therapeutic strategies for breast cancer treatment