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Rab11 Regulates Lumen Formation and Morphogenesis in the Developing Pancreas
Get PDFThe molecular links between epithelial lumenogenesis and tissue-level morphogenesis in the pancreas remain elusive despite a decade of studies. Here, I show that deletion of Rab11A and Rab11B (Rab11) in the developing pancreatic epithelium (Rab11pancDKO) disrupts both of these processes. The loss of Rab11 in the pancreas results in ~50% neonatal lethality, with the surviving pups failing to thrive. Surviving adult Rab11pancDKO mice are smaller and exhibit defective endocrine function. Loss of Rab11 in the pancreas results in severe morphogenetic defects that are associated with a decrease in endocrine mass during embryonic development. Additionally, Rab11pancDKO pancreata are unable to properly form and connect lumens. Rab11pancDKO cells exhibit defects in coordinating singular apical membrane initiation sites (AMIS) between groups of cells. We show that these phenotypes are due, at least in part, to failures in vesicle trafficking, as apical components remain trapped within Rab11pancDKO cells. These observations suggest Rab11 directly regulates epithelial lumen formation and morphogenesis, which are in turn critical for pancreatic cell fate specification. Furthermore, careful analysis of WT early-stage pancreata reveal the active role of cap cells in microlumen formation. In addition, a literature review of Rho GTPase signaling in the vasculature reinforces many of the fundamental roles of various signaling molecules that also govern pancreas development. These reports link a number of cellular processes in vivo, and presents tantalizing possibilities for decoding pancreatic morphogenesis
Structural Biology in Cellular Environments Using Sensitivity Enhanced NMR
Get PDFThis dissertation describes the general applicability of DNP solid state NMR to mammalian cells. DNP NMR can detect proteins at their physiological concentrations within cellular environment in tractable times. However, these experiments were limited to cellular lysates, which did not recapitulate the intracellular environment completely. Studying proteins within their native cellular environment required in-cell NMR. This work focuses on developing methodology for in-cell DNP NMR and applying the technique to investigate the conformational ensemble of Tau. Chapter 1 provides an overview of in-cell NMR in biological systems and intrinsically disordered proteins. A brief primer of NMR, DNP and EPR is also provided in this chapter. Chapter 2 describes the development of methodology to maintain biological integrity of mammalian cells during DNP NMR. Description of a novel method to insert samples into a spectrometer is added as a supplementary chapter 2. Chapter 3 is based on a comparative study between different cryoprotectants to optimize biological integrity for in-cell DNP NMR. Chapter 4 focusses on the characterization of the reduction process of a polarizing agent, AMUPol inside intact and lysed HEK293 cells using electron paramagnetic resonance (EPR) spectroscopy. In the supplementary chapter 4, a novel DNP radical AsymPol-POK and its reduction kinetics within intact HEK293 cells is discussed. Chapter 5 deals with the application of in-cell DNP NMR to study the conformational ensemble of tau protein within cellular environment.
The in-cell DNP NMR methodology developed in this work can be potentially applied to various biological systems. Additionally, the strategies and experiments described here to investigate the conformational ensemble of an intrinsically disordered protein, tau, within cellular environment, can be tailored to any other IDP or protein of interest within normal or pathological cellular milieu. Also, the EPR experiments described here will be a useful guide to test reduction kinetics of novel polarizing agents for in-cell DNP NMR. Overall, this dissertation should serve as a useful literature for technical advancement and biological application of in-cell DNP NMR
The Role of Protocadherin 7 in Lung Adenocarcinoma
Get PDFLung cancer is the leading cause of cancer-associated deaths worldwide. Despite recent advances in the development of targeted therapies for lung cancer, most patients develop resistance to these targeted therapies. Our lab has uncovered a key oncogenic role for Protocadherin 7 (PCDH7) in non-small cell lung cancer (NSCLC) (Zhou et al. Cancer Research, 2017; Zhou et al. Molecular Cancer Research, 2019). PCDH7 is frequently overexpressed in human lung cancers, significantly correlating with poor clinical outcome of lung adenocarcinoma patients. PCDH7 knockout in established lung tumor xenografts led to a significant decrease in phospho-EGFR, leading us to hypothesize that PCDH7 may directly interact with EGFR and modulate signaling through this receptor. We demonstrate that PCDH7 interacts with EGFR in a phospho-dependent manner, and that loss of this interaction in PCDH7 truncation mutants reduces EGFR activity and downstream signaling. PCDH7 knockout cells also exhibit decreased EGFR dimerization, suggesting a model whereby PCDH7 promotes EGFR dimerization to stimulate downstream MAPK activation. We also investigated the consequences of PCDH7 loss of function in EGFR mutant human cells and mouse models. Knockout of PCDH7 sensitizes EGFR mutant cell lines to tyrosine kinase inhibitors (TKIs), the current method of treatment for EGFR mutant lung cancers. Furthermore, loss of PCDH7 in EGFR mutant xenografts and genetically engineered mice reduces overall tumor burden. Overall, these findings reveal a new mechanism through which PCDH7 potentiates the MAPK pathway and provide strong rationale for the development of PCDH7-targeting molecules including monoclonal antibodies
What every internist should know about post-acute and long-term care
Get PDFDetailed formal protocol with illustrations and extensive bibliography.Detailed formal protocol with illustrations and extensive bibliography.A recording of the protocol presentation is available on UT Southwestern’s Mediasite. Note: Access to the video is restricted to authorized UT Southwestern users only.UT Southwestern--Internal Medicin
Mitochondrial Metabolism of Human Kidney Cancers
No full textThe general metadata -- e.g., title, author, abstract, subject headings, etc. -- is publicly available, but access to the submitted files is restricted to UT Southwestern campus access and/or authorized UT Southwestern users.Metabolism is often dysregulated in cancer. Pinpointing the exact metabolic requirements critical for cancer cell survival has been the subject of intense study for the last 100 years. However, very few metabolic targets have successfully translated to effective therapies for patients. Progress in clinical translation has been limited as the vast majority of cancer metabolism studies are currently conducted in preclinical models of cell culture and mice. How relevant these preclinical studies are to disease biology in humans is almost entirely unknown. I use a multidisciplinary approach to infuse 13C-labeled nutrients during surgical tumor resection in over 80 patients with kidney cancer. Labeling from [U-13C]glucose varies across cancer subtypes, indicating that the kidney environment alone cannot account for all metabolic reprogramming in these tumors. Compared to the adjacent kidney, clear cell renal cell carcinomas (ccRCC) display suppressed labelling of tricarboxylic acid (TCA) cycle intermediates in vivo and in organotypic slices cultured ex vivo, indicating that suppressed labeling is tissue intrinsic. Infusions of [1,2-13C]acetate and [U-13C]glutamine in patients, coupled with respiratory flux of mitochondria isolated from kidney and tumor tissue, reveal primary defects in mitochondrial function in human ccRCC. However, ccRCC metastases unexpectedly have enhanced labeling of TCA cycle intermediates compared to primary ccRCCs, indicating a divergent metabolic program during ccRCC metastasis in patients. In mice, stimulating respiration in ccRCC cells is sufficient to promote metastatic colonization. Altogether, these findings indicate that metabolic properties evolve during human kidney cancer progression, and suggest that mitochondrial respiration may be limiting for ccRCC metastasis but not for ccRCC growth at the site of origin
Missed Breast Cancer Risk Factors and Clinicopathologic Features: A Six-Year Analysis of Data from a Single Institution
Get PDFBACKGROUND: Breast cancer is the second most commonly diagnosed cancer in women, but mortality has been consistently decreasing due to the introduction of screening mammography and continual innovations in treatment [1,13,15]. However, cancers missed on screening and diagnostic imaging studies impede further reductions in mortality, necessitating scrutiny of common themes in these cases.
OBJECTIVE: To investigate common characteristics of breast cancers missed on multimodality screening or diagnostic imaging at a single institution.
METHODS: In an IRB-approved, HIPAA compliant retrospective study, we identified all patients who received a BI-RADS 1-3 assessment and were subsequently diagnosed with breast cancer within 1 year of their negative imaging study taken between January 1, 2014 and January 31, 2020 in our institution. We collected age, ethnicity, BI-RADS rating, time elapsed before detection, imaging modality that missed/detected the cancer, symptomatic/asymptomatic status at the time of diagnosis, presenting symptom, type, size, grade, hormone receptor positivity, lymph node positivity, Ki-67, family history of breast cancer, personal history of breast cancer, time elapsed since previous diagnosis, same/contralateral breast recurrence, mutation and treatment from patient charts. A matched cohort based on mammographic breast density was created from true positive cancers randomly selected from studies with BIRADS 4-5 designation in patients whose biopsies revealed cancer within the same time frame. For comparison, we used Pearson's chi-squared to evaluate discrete variables and unpaired student's t-test with unequal variance to evaluate continuous variables with p value significance at <0.05.
RESULTS: We identified 154 false negative studies corresponding to 128 missed cancers given that cancers were missed on more than one imaging study in some patients. The comparison cohort comprised 127 breast density matched true positive cancers. Mean age (60.94 years vs. 60.99 years, p=0.97) and race [(White 76.56%, Black 12.50%, Asian 3.91%, Hispanic 6.25% and Other 0.78%) vs. (White 67.72%, Black 18.11%, Asian 5.51% and Hispanic 8.66%), p=0.43] were not significantly different between false negative and true positive groups. There was a higher rate of patients symptomatic at the time of diagnosis (59.38% vs. 46.46%, p=0.039) and a higher rate of patients with deleterious genetic mutations (18.75% vs. 6.30%, p=0.0027) in the false negative cohort. There was a significantly increased rate of prior personal history of breast cancer (40.63% vs. 18.90%, p<0.001) and family history of breast cancer (68.75% vs. 48.82%, p=0.0049) in the false negative cohort. Personal history of breast cancer (36.84% vs. 13.56%, p=0.0024) and family history of breast cancer (65.79% vs. 45.76%, p=0.020) remained statistically significant even when asymptomatic cancers, including asymptomatic MRI-detected cancers were removed. Mean tumor size was significantly smaller in the false negative cohort (21.19 mm vs. 32.38 mm, p= 0.0014). False negative studies were screening mammogram in 34.42% (53/154), screening digital breast tomosynthesis in 23.38% (36/154), diagnostic mammography in 21.43% (33/154), diagnostic digital breast tomosynthesis in 7.79% (12/154), ultrasound in 6.49% (10/154) and MRI in 6.49% (10/154). False negative cancers were detected with diagnostic mammography in 26.56% (34/128), MRI in 26.56% (34/128), ultrasound in 17.97% (23/128), diagnostic digital breast tomosynthesis in 14.06% (18/128), screening digital breast tomosynthesis in 8.59% (11/128), ultrasound guided biopsy in 1.56% (2/128), chest CT in 0.78% (1/128) and outside study in 0.78% (1/128). In the true positive cohort, cancer was detected with screening mammography in 43.31% (55/127), diagnostic mammography in 37.80% (48/127), screening digital breast tomosynthesis in 11.02% (14/127), ultrasound in 4.72% (6/127), diagnostic digital breast tomosynthesis in 1.57% (2/127) and breast MRI in 1.57% (2/127).
CONCLUSION: Surveillance in breast cancer survivors follows standard recommendations of annual mammography [16,20]. These findings invite the notion that supplemental screening to detect interval cancers may be useful in breast cancer survivors
Differences in Short-Term Sport-Specific Functional Recovery After Primary ACL Reconstruction in the Adolescent Athlete
No full textThe general metadata -- e.g., title, author, abstract, subject headings, etc. -- is publicly available, but access to the submitted files is restricted to UT Southwestern campus access and/or authorized UT Southwestern users.The entirety of the article was accepted for publication by Sports Health Journal in January 2023. This thesis is altered by having a greater length and slightly different format than that accepted for publication, but all sections of this manuscript (including the abstract) share most material with the accepted manuscript, which is available at the related citation below.BACKGROUND: Physical requirements vary from sport to sport which may affect the physiologic and psychologic demand placed on an athlete. Although ACL injury rates have been studied extensively, it is unclear whether levels of functional and psychological readiness for return-to-sport after primary ACL reconstruction (ACLR) differ based on an athlete's primary sport.
OBJECTIVE: We hypothesize that youth athletes in different primary sports will demonstrate differences in short-term functional recovery, as well as patient reported psychological and functional recovery after primary ACLR.
METHODS: After IRB approval was obtained, data on consecutive patients in a pediatric sports medicine clinic treated for ACL injury (12/2015-12/2019) was reviewed. Patients included had undergone primary ACLR within this window and reported sports participation at the time of injury. Patients were excluded if they had undergone an ACLR prior to December 2015, experienced bilateral tears prior to surgery, had only partial tears, underwent multi-ligamentous reconstruction/repair, or were diagnosed with congenital absence of an ACL. After screening the patients, 104 were excluded, leaving 443 athletes for further review. Records were reviewed for patient demographic data, sports participation, surgical data, functional testing scores (Y Balance TestTM), both functional (Pedi-FABS and Pedi-IKDC) and psychological (ACSI-28, ACL-RSI, and AIMS) patient reported outcome measures (PROM), and timing of return-to-play clearance. Y Balance TestTM (YBT) passage was determined by analysis of anterior side-to-side difference, posteromedial and posterolateral side-to-side differences, and composite scores. The providing surgeon used YBT performance as the primary metric for determination of clearance. Based on the most commonly reported sports, four groups were studied: soccer, football, basketball, and other.
RESULTS: The cohort was split by gender with 220 male and 223 female athletes. 65.28% of soccer players were female and 100% of football players were male (p<0.01). At initial postoperative YBT testing (6-9 months), soccer players had higher operative (p<0.01) and nonoperative (p<0.01) leg composite scores when compared to basketball. No significant differences were found between sports in functional or psychological PROMs at pre-surgical baseline or 6 months post-operatively. When compared to football, soccer players completed functional clearance in a shorter time from surgery (p=0.02). Multivariate analysis showed level of competition as a significant independent variable for clearance in female athletes.
CONCLUSION: After primary ACLR, athletes demonstrated short-term sport-specific differences in YBT scores, especially females. Differences in time from surgery to clearance were also demonstrated between sports, with soccer players attaining clearance sooner than football players. Level of competition influenced YBT composite scores in all athletes and time to clearance in female athletes. Sport-specific differences in reinjury should be investigated to determine if changes in evaluation for return-to-play should be implemented
Development and Implementation of Teamwork and Communication Education for Medical Students in the Internal Medicine Learning Environment
Get PDFBACKGROUND: There exists a lack of structured teamwork education and practice in undergraduate medical education, which in part translates to poor teamwork and communication by residents and attendings on interdisciplinary clinical teams. Such lapses in communication and dysfunctional clinical teams have repeatedly been identified in root cause analyses of medical error.
LOCAL PROBLEM: At our institution, students have limited structured opportunities to practice and integrate teamwork and communication skills in safe, controlled environments during their formative clinical education.
AIM: To design and implement a teamwork education module in the Internal Medicine 4th year medical student 'sub-internship' rotation, and evaluate its efficacy.
INTERVENTION: This intervention is the fourth in a series of five educational experiences being implemented throughout the medical school curriculum, designed to engage students in learning and practicing effective communication in interprofessional settings as part of a longitudinal initiative known as TeamFIRST. Students in the internal medicine sub-internship will partake in activities related to observation and participation of communication, coordination, and teamwork skills. At the end of the course, they will debrief and reflect on their experiences to allow for cognitive practice and feedback. Similar interventions are being incorporated into emergency medicine and surgery clinical learning settings, with the results and outcomes compared.
RESULTS: Analysis of data from 32 students shows a significant improvement in confidence in skills and knowledge of teamwork competencies after the completion of the module. No significant improvement was seen in attitudes towards teamwork competencies, however initial attitudes were already positive. Implementation science outcomes including fidelity, acceptability, and sustainability were also measured, demonstrating moderate fidelity, high acceptability, and poor sustainability.
CONCLUSION: This intervention suggests promising outcomes in improving student knowledge, skills, and attitudes towards teamwork and communication proficiencies, however much work needs to be done to improve the implementation outcomes of the intervention to allow for sustainability and generalizability
Woman
Get PDFI was reflecting upon how a woman's actions are misinterpreted and misunderstood and more often than not, underestimated. Our resilience and innate strength comes out in full force when there is a platform and freedom of expression
Pilot Emergency Care Assessment of Tertiary Hospitals in Kathmandu, Nepal Using the WHO Tool
No full textThe general metadata -- e.g., title, author, abstract, subject headings, etc. -- is publicly available, but access to the submitted files is restricted to UT Southwestern campus access and/or authorized UT Southwestern users.BACKGROUND: Strengthening emergency care is recognized as one of the most cost-effective public health interventions, and low-cost emergency care interventions are known to save lives, whether in a disaster setting or otherwise.
OBJECTIVE: To assess the readiness of health facilities in Kathmandu, Nepal as the first step in identifying disaster and disease outbreak preparedness.
METHODS: Qualitative assessment using the WHO hospital unit emergency assessment tool with additional questions on disaster preparedness, COVID-19 response capacity, and burn care capabilities. The six tertiary emergency centers in and around the Kathmandu Valley that were assessed included one public-teaching hospital (Bir), two private-teaching hospitals (Patan and Dhulikhel), one public non-teaching hospital (National Trauma Center), and two private non-teaching hospital (Grande and HAMS).
RESULTS: Private hospitals showed greater emergency capacity specifically in infrastructure and essential equipment, sepsis interventions, and obstetric intervention. Patan and Dhulikhel, both private teaching hospitals, showed perfect 3.00 scores for obstetric and sepsis intervention capabilities. Grande and HAMS, private non-teaching hospitals, also had perfect 3.00 scores for sepsis intervention capabilities.
Patan, Dhulikhel, and NTC (a public non-teaching hospital) showed perfect 3.00 scores in their burn intervention capabilities. Patan showed a 3.00 score for vital signs/airway/breathing interventions, and NTC showed a 3.00 score for ancillary services. This study showed that emergency rooms in tertiary hospitals in Kathmandu excel in different areas and there is room for improvement in other areas.
Bir Hospital, the public teaching hospital in this study, was burdened the most by the second wave of COVID-19. It has the most room for improvement, especially in obstetric interventions, consulting services, burn interventions, and trauma interventions.
CONCLUSION: This study has shown the validity and reliability of the WHO Emergency Unit Assessment Tool and has set the standard for a larger more comprehensive national emergency care evaluation in Nepal. The partnerships made with local Nepali researchers has enhanced the local researchers' ability to conduct research and build support networks. These results will help guide future emergency disaster response capacity building and training, assess the disaster preparedness of emergency departments, and advance the field of emergency medicine in Nepal